DOI: 10.3897/jucs.150679

Authors: Stefan Lengauer, Lin Shao, Hossein Miri, Michael Bedek, Cordula Kupfer, Maria Zangl, Bettina Kubicek, Barbara Dienstbier, Klaus Jeitler, Cornelia Krenn, Thomas Semlitsch, Carolin Zipp, Dietrich Albert, Andrea Siebenhofer, Tobias Schreck

Abstract: The effective and targeted provision of health information to consumers, specifically tailored to their needs and preferences, is indispensable in healthcare. With access to appropriate health information and adequate understanding, consumers are more likely to make informed and healthy decisions, become more proficient in recognizing symptoms, and potentially experience improvements in the prevention or treatment of their medical conditions. Most of today’s health information, however, is provided in the form of static documents. In this paper, we present a novel and innovative visual health information system based on adaptive document visualizations. Depending on the users’ information needs and preferences, the system can display its content with document visualization techniques at different levels of detail, aggregation, and visual granularity. Users can navigate using content organization along sections or automatically computed topics, and choose abstractions from full texts to word clouds. Our first contribution is a formative user study which demonstrated that the implemented document visualizations offer several advantages over traditional forms of document exploration. Informed from that, we identified a number of crucial aspects for further system development. Our second contribution is the introduction of an interaction provenance visualization which allows users to inspect which content, in which representation, and in which order has been received. We show how this allows to analyze different document exploration and navigation patterns, useful for automatic adaptation and recommendation functions. We also define a baseline taxonomy for adapting the document presentations which can, in principle, be leveraged by the observed user patterns. The interaction provenance view, furthermore, allows users to reflect on their exploration and inform future usage of the system.

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DOI: 10.3897/jucs.164654

Authors: Wolfram Luther, A. J. Han Vinck

Abstract: This volume presents a conference paper selection from the 4th Workshop on Collaborative Technologies and Data Science in Smart City Applications (CODASSCA 2024): Data Science and Reliable Machine Learning, held in Yerevan, Armenia, October 3-6, 2024, https://codassca2024.aua.am/. The special issues guest editors invited five groups of authors from Armenia, Chile, Germany, the UK, and the USA to submit enlarged versions of their CODASSCA 2024 papers There was also a J.UCS open call so that any author could submit papers on the highlighted subjects. The invitation to review the 16 contributions received was accepted by 16 experts, and, after three rounds, seven articles were finally accepted for publication in the special issue.

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DOI: 10.3897/jucs.110173

Authors: Darwin Alulema, Maximiliano Paredes-Velasco, Ricardo de Arriba Lasso

Abstract: Teaching technical content in science and engineering requires the development of high-level competencies such as analytical and critical thinking skills, and is perceived by students as a difficult subject to understand. One way to help students learn this type of content is through the use of scaffolding, which dynamically regulates and adjusts learning according to the student’s needs. Although the use of scaffolding has already been applied in different educational contexts, so far there are no studies analysing its impact on students’ emotions and perception. In this paper we propose the LESCA system, which performs adaptive content feedback through scaffolding. The main hypothesis of this article is that the use of this tool together with teacher scaffolding improves the acquisition of content at higher cognitive levels and improves the student’s emotional state during learning. An experience has been carried out with 36 students of Industrial Electronics and Robotics Associate Degree with a pre-post design, where one group of students did not use the tool and another one did. The findings indicate that knowledge acquisition at the higher levels of Bloom’s taxonomy improved after the use of technological scaffolding and that this acquisition improved significantly when incorporating teacher scaffolding. On the other hand, students who performed the tasks with the system experienced significantly less anxiety and despair than students who did not use it. In addition, it has been found that students perceive teacher scaffolding to be significantly more useful than technological scaffolding.

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DOI: 10.3897/jucs.112556

Authors: Nelson Baloian, Jonathan Frez, José A. Pino, Cristóbal Fuenzalida, Sergio Peñafiel, Belisario Panay, Gustavo Zurita, Horacio Sanson

Abstract: We present a methodology to handle the problem of planning sales goals. The methodology supports the retail manager to carry out simulations to find the most plausible goals for the future. One of the novel aspects of this methodology is that the analysis is based not on current sales levels, as most previous works do, but on those in the future, making a more precise and accurate analysis of the situation. The work presents the solution for a scenario using three sales performance indicators: foot traffic, conversion rate and ticket mean value for sales, but it explains how it can be generalized to more indicators. The contribution of this work is in the first place a framework, which consists of a methodology for performing sales planning, then, an algorithm, which finds the best prediction model for a particular store, and finally, a tool, which helps sales planners to set realistic sales goals based on the predicted sales. First we present the method to choose the best indicator prediction model for each retail store and then we present a tool which allows the retail manager estimate the improvements on the indicators in order to attain a desired sales goal level; the managers may then perform several simulations for various scenarios in a fast and efficient way. The developed tool implementing this methodology was validated by experts in the subject of administration of retail stores yielding good results.

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DOI: 10.3897/jucs.94162

Authors: Zhiling Yang

Abstract: Natural Language Processing (NLP) is an efficient method for enhancing educational outcomes. In educational settings, implementing NLP entails starting the learning process through natural acquisition. English teaching and learning have received increased attention from the relevant education departments as an integral aspect of the new curriculum reform. The environment of English teaching and learning is undergoing extraordinary changes as a result of the constant improvement and extension of teaching level and scale, as well as the growth of Internet information technology. As a result, the current research aims to look into techniques for efficiently using AI (artificial intelligence) apps to teach and learn English from the perspective of university students. This research can measure the levels as well as effectiveness of the employment of AI applications for teaching English based on deep learning techniques. There, the NLP based language enhancement has been carried out using Character-level recurrent neural network with back Propagation neural network (Cha_RNN_BPNN) based classification. With the help of this DL (deep learning) technique, it is possible to use AI methods to assist teachers in analysing and diagnosing students' English learning behaviour, replacing teachers in part to answer students' questions in a timely manner, and automatically grading assignments during the English teaching process. Experimental analysis shows Word Perplexity, Flesch-Kincaid (F-K) Grade Level for Readability, Cosine Similarity for Semantic Coherence, gradient change of NN, validation accuracy, and training accuracy of the proposed technique.

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DOI: 10.3897/jucs.94134

Authors: Loveleen Kumar, Manish Jain

Abstract: Image superresolution (SR) is the process of enlarging and enhancing a low-resolution image. Image superresolution helps in industrial image enhancement, classification, detection, pattern recognition, surveillance, satellite imaging, medical diagnosis, image analytics, etc. It is of utmost importance to keep the features of the low-resolution image intact while enlarging and enhancing it. In this research paper, a framework is proposed that works in three phases and generates superresolution images while keeping low-resolution image features intact and reducing image blurring and artifacts. In the first phase, image enlargement is done, which enlarges the low-resolution image to the 2x/4x scale using two standard algorithms. The second phase enhances the image using an AI-empowered Generative adversarial network (GAN). We have used a GAN with dual generators and named it EffN-GAN (EfficientNet-GAN). Fusion is done in the last phase, wherein the final improved image is generated by fusing the enlarged image and GAN output image. The fusion phase helps in reducing the artifacts. We have used the DIV2K dataset to train the GAN and further tested the results on the images of Set5, Set14, B100, Urban100, Manga109 datasets with ground truth of size 224x224x3. The obtained results were compared with the state-of-the-art superresolution approach based on important image quality parameters, namely, Peak signal-to--to-noise ratio (PSNR), Structural similarity index (SSIM), Visual information fidelity (VIF) image quality parameters. The results show that the proposed framework for generating super-resolution images from 2x/4x resolution downgraded images improves the aforementioned mentioned image quality parameters significantly.

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DOI: 10.3897/jucs.94161

Authors: Abhishek Kumar, Abdul Khader Jilani Saudagar, Mohammed AlKhathami, Badr Alsamani, Muhammad Badruddin Khan, Mozaherul Hoque Abul Hasanat, Ankit Kumar

Abstract: Virtual Reality (VR) has made considerable gains in the consumer and professional markets. As VR has progressed as a technology, its overall usefulness for educational purposes has grown. On the other hand, the educational field struggles to keep up with the latest innovations, changing affordances, and pedagogical applications due to the rapid evolution of technology. Therefore, many have elaborated on the potential of virtual reality (VR) in learning. This research proposes a novel techniques customized curriculum for medical students and recommendations for their learning process based on deep learning techniques. Here the data has been collected based on the pre-historic performance of the student and their current requirement and these data have been created as a dataset. Then this has been processed for analysis based on CAD system integrated with deep learning techniques for creating a customized curriculum. Initially this data has been processed and analysed to remove missing and invalid data. Then these data were classified for creation of the curriculum using a gradient decision tree integrated with naïve Bayes. From this, the customized curriculum has been generated. Based on this customized curriculum, the learning approach recommendation has been carried out using the fuzzy rules integrated knowledge-based recommendation system. The experimental results of the proposed technique have been carried out with an accuracy of 98%, specificity of 82%, F-1 score of 79%, information overload of 75%, and precision of 81%.

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DOI: 10.3897/jucs.94133

Authors: Ashok Kumar Saini, Roheet Bhatnagar, Devesh Kumar Srivastava

Abstract: Machine learning is a branch of computer science concerned with developing algorithms & models capable of ‘learning through data and iterations’. Deep learning simulates the structure and function of human organs and diseases using artificial neural networks with more than one hidden layer. The primary purpose of this work is to develop and test computer vision and machine learning algorithms for classifying Huanglongbing (HLB)-infected, healthy, and unhealthy leaves and fruits of the citrus plant. The images were segmented using a normalized graph cut, and texture information was extracted using a co-occurrence matrix. The collected attributes were used for classification and support vector machine (SVM), and deep learning methods were employed. When rating the classification outcomes, the accuracy of the classification and the number of false positives and false negatives were considered. The result shows that Deep Learning could create categories up to 96.8% of HLB-infected leaves and fruits. Despite a broad variance in intensity from leaves collected in North India, this method suggests it could be beneficial in diagnosing HLB.

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DOI: 10.3897/jucs.94132

Authors: Vijay Krishna Pallaw, Kamred Udham Singh

Abstract: The network’s convenience has created a copyright dilemma for some multimedia works. Nowadays, every healthcare system relies on digital medical images for diagnosis. These medical images are transmitted through communication channels, so there is a risk of tampering and copyright violation. A digital watermarking system can ensure and guarantee that tampering and copyright violation are prevented. This study presents a nonblind digital watermarking approach to X-ray medical images based on Contourlet transform (C.T.) and Slantlet Transform (SLT). Since the two-dimensional signals are represented flexibly by contourlet transforms, the contour plot can be used efficiently to represent curves and smooth contours. At the same time, the SLT has better time-localization & smoothness properties. The maximum energy of an image is conceived in the LL band if SLT transform are employed. Therefore, the LL band is used to entrench the watermark. The additive quantization method has been used to entrench the watermark. The efficiency of our scheme is assessed by different quality parameters and compared with several existing schemes. The results of the experiment show that the proposed scheme performs better and has the ability to resist several attacks.

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DOI: 10.3897/jucs.94160

Authors: Xin Ma

Abstract: Higher vocational education is a self-contained method of higher education that is aligned with global productivity and economic development. Its goal is to develop talented workers who contribute significantly to the economy and industry. Teaching analysis, teaching strategy, teaching practice, and assessment are all part of the course design process in high vocational education. Teaching assessment is one of the most effective methods for improving the quality of course teaching among teaching processes. This research proposes novel techniques in English teaching based on artificial intelligence for course selection based on students' feedback. Here, the dataset has been collected based on the students’ feedback on courses for Higher Vocational Education in English teaching. This dataset has been processed to remove invalid data, missing values, and noise. The processed data features have been dimensionality reduction integrated with K-means neural network. And the extracted features have been classified with higher accuracy using recursive elimination-based convolutional neural network. Based on this feedback data classification, recommendation for courses in Higher Vocational Education in English teaching has been suggested. The experimental analysis shows various students' feedback dataset validation and training in terms of accuracy of 96%, precision of 92%, recall of 93%, RMSE of 68%, and computational time of 65%.

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DOI: 10.3897/jucs.94127

Authors: Lalan Kumar, Kamred Udham Singh

Abstract: Watermarking is a valuable technique for verifying medical images obtained through the internet for diagnosis. There is a greater need for security in medical pictures with ever- increasing security risks. This research presented a Finite Ridgelet Transform (FRT)-Hessenberg based watermarking scheme in medical images. The suggested paradigm is divided into two stages. Before watermark insertion, FRT is applied to medical images. The coefficients are combined into blocks of 4 x 4 and each block is decomposed using Hessenberg decomposition. The second column of the Q matrix is used to insert the watermark using the additive quantization technique. The results obtained from our experiment have given good visual quality of the watermarked images. The high PSNR value 53.6121 and NC value 1.0 show that our scheme is performing better. Moreover, the performance of our scheme is robust against several attacks. The consequences of this result imply that the anticipated scheme is effective for medical image watermarking.

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DOI: 10.3897/jucs.76535

Authors: Stefano Masneri, Ana Domínguez, Mikel Zorrilla, Mikel Larrañaga, Ana Arruarte

Abstract: Augmented reality is a technology that enhances human perception with additional, artificially generated sensory inputs. This creates new experiences enriching human vision by combining natural with digital elements. Augmented reality development dates back to the early sixties but it is only in the last decade, thanks to improvements to hardware and software, when it has begun to be rapidly incorporated in several fields, including education. This study presents a systematic review of the literature on the use of augmented reality applications in primary and secondary schools, with a specific focus on collaborative, multi-user and interactive applications. The aim of the study is to investigate the characteristics of such applications, the processes that led to their adoption, and their effectiveness in enhancing the learning experience. This study synthesises a set of 100 publications from 2015 to 2020 and performs a qualitative analysis of their content. The review describes the current state of the art in research in augmented reality for education and provides future research lines, as well as trends for the future of such applications in educational settings, analysing the relevance of the multi-user interaction challenge within the augmented reality ecosystem.

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DOI: 10.3897/jucs.68384

Authors: Fabian Honegger, Yuan Feng, Matthias Rauterberg

Abstract: Adequate use of multimodal stimuli plays a crucial role in help forming the sense of presence within a virtual environment. While most of the presence research attempts to engage more sensory modalities to induce a higher sense of presence, this paper investigates the relevance of each sensory modality and different combinations on the subjective sense of presence using a specifically designed scenario of a passive experience. We chose a neutral test scenario of “waiting at a train station while a train is passing by” to avoid the potential influence of story narrative on mental presence and replicated realistic multimodal stimuli that are highly relevant to our test setting. All four stimuli - visual, auditory, vibration, and draught - with 16 possibilities of combinations were systematically evaluated with 24 participants. The evaluation was performed on one crucial aspect of presence – “realness” to reflect user presence in general. The perceived realism value was assessed using a scalometer. The findings of main effects indicate that the auditory stimuli had the most significant contribution in creating the sense of presence. The results of interaction effects suggest the impact of draught stimuli is significant in relation to other stimuli - visual and auditory. Also, the gender effects revealed that the sense of presence reported by female participants is influenced by more factors than merely adding more sensory modalities.

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DOI: 10.3897/jucs.66265

Authors: Güldem Alev Özkök

Abstract: This research aims to model the process of data visualization (DV) and design to facilitate computational thinking (CT) of secondary-level students. As an interdisciplinary method for visualizing complex data, creating data visualizations requires learners to analyze data from knowledge of pure and applied science. This study investigates creating DV to facilitate CT as an interdisciplinary method which combines mathematics and information technology. The study was carried out using synthesised design-based research (DBR) method by conducting two cycles comprised of five phases: problem analysis within real-life context, design solution, develop solution, evaluate in practice and reflection. CT dimensions (decomposition, pattern recognition, abstraction, and algorithm design) were tested by using the Computational Thinking through Data Visualization Rubric and reflection form acquired during implementation. The sample consisted of secondary school students in the data visualization creation process with 27 in the first cycle and 31 in the second cycle. This research proposes a model to facilitate development of CT by DV with the analysis of complex data, creating an effective method by enabling analytics and visualizing data. The proposed DV development process facilitating CT has the potential to inform research on interdisciplinary learning environments.

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DOI: 10.3897/jucs.2020.026

Authors: Kheir Daouadi, Rim Rebaï, Ikram Amous

Abstract: Nowadays, bot detection from Twitter attracts the attention of several researchers around the world. Different bot detection approaches have been proposed as a result of these research efforts. Four of the main challenges faced in this context are the diversity of types of content propagated throughout Twitter, the problem inherent to the text, the lack of sufficient labeled datasets and the fact that the current bot detection approaches are not sufficient to detect bot activities accurately. We propose, Twitterbot+, a bot detection system that leveraged a minimal number of language-independent features extracted from one single tweet with temporal enrichment of a previously labeled datasets. We conducted experiments on three benchmark datasets with standard evaluation scenarios, and the achieved results demonstrate the efficiency of Twitterbot+ against the state-of-the-art. This yielded a promising accuracy results (>95%). Our proposition is suitable for accurate and real-time use in a Twitter data collection step as an initial filtering technique to improve the quality of research data.

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DOI: 10.3217/jucs-025-13-1761

Authors: Estêvão Saleme, Celso A. S. Santos, Ricardo Falbo, Gheorghita Ghinea, Frederic Andres

Abstract: Designing a mulsemedia|multiple sensorial media|system entails first and foremost comprehending what it is beyond the ordinary understanding that it engages users in digital multisensory experiences that stimulate other senses in addition to sight and hearing, such as smell, touch, and taste. A myriad of programs that comprise a software system, several output devices to deliver sensory effects, computer media, among others, dwell deep in the realm of mulsemedia systems, making it a complex task for newcomers to get acquainted with their concepts and terms. Although there have been many technological advances in this field, especially for multisensory devices, there is a shortage of work that tries to establish common ground in terms of formal and explicit representation of what mulsemedia systems encompass. This might be useful to avoid the design of feeble mulsemedia systems that can be barely reused owing to misconception. In this paper, we extend our previous work by proposing to establish a common conceptualization about mulsemedia systems through a domain reference ontology named MulseOnto to aid the design of them. We applied ontology verification and validation techniques to evaluate it, including assessment by humans and a data-driven approach whereby the outcome is three successful instantiations of MulseOnto for distinct cases, making evident its ability to accommodate heterogeneous mulsemedia scenarios.

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DOI: 10.3217/jucs-025-12-1625

Authors: Carlos De Carvalho, Pedro Cano, José Roa, Anna Wanka, Franz Kolland

Abstract: Being able to effectively use online tools has become a fundamental competence in our Society. Therefore, it is important to tackle the age digital divide as there is a rapidly growing number of elderly people. Like everyone else, older adults (senior citizens or the silver generation) must be equipped with the necessary skills to be able to be connected and integrated in the online world to prevent their social isolation and to foster their inclusion. As a contribution to that effort, a European-wide digital literacy development initiative for senior citizens was setup and this article presents the analysis of the achieved results which shows a very positive perception of the seniors on the developed digital abilities.

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DOI: 10.3217/jucs-025-11-1437

Authors: Samo Tomažič, Igor Bernik

Abstract: Cyberattacks targeting the nuclear sector are now a reality; they are becoming increasingly frequent and sophisticated, while the perpetrators are increasingly motivated. The key stakeholders in the nuclear sector, such as nuclear facility operators, nuclear regulators responsible for nuclear safety or nuclear security, technical support organisations and computer equipment suppliers, must take the necessary cybersecurity measures to prepare for potential cyberattacks and provide the highest possible level of response to such cyberattacks. This can only be achieved by adopting a systematic approach to cyberattack response. When conducting the research study presented herein, a descriptive method was applied to review the scientific literature, various standards, recommendations and guides, as well as to devise an inventory of publicly available sources. On the basis of such an analysis, individual questions were then formulated in order to compile a structured interview, which was conducted with international experts working at nuclear facilities, nuclear regulators, technical support organisations, computer equipment suppliers and other organisations responsible for providing cybersecurity in the nuclear sector. On the basis of their responses, researchers devised an innovative and comprehensive Cyberattack Response Model to be used by Slovenia's nuclear safety regulator and the regulator responsible for the physical protection of nuclear facilities and nuclear and radioactive materials.

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DOI: 10.3217/jucs-025-10-1261

Authors: Akhtar Ali, Imran Bajwa, Rafaqat Kazmi

Abstract: his paper describes a hybrid CPU/GPU approach for solving a two-phase mathematical model numerically. The dynamic of drug release between the first phase (coating) and second phase (arterial tissue) is represented by a system of partial differential equations (PDEs). The system of equations is discretized by Finite Element Method. The whole discretized system involves a large sparse system of equation which requires a high computation. The CPU/GPU approach provides a platform to solve PDEs having extensive computations in parallel. Consequently, this platform can significantly reduce the solution times as compared to the implementation of CPU. This allows for more efficient investigation of different mathematical models, as well as, the governing parameters. In this paper, a significant parallel computing framework is presented to solve the governing equations numerically using the Graphics Processing Units (GPUs) with CUDA. This two-phase model investigates the impact of key parameters related to mass concentrations and drug release from tissue and coating layers. The identification and the role of major parameters such as (Filtration velocity, the ratio of accessible void volume to solid volume, the solid-liquid mass transfer rate) are tinted. Furthermore, the motivation and guidance for using parallel computing in order to handle computational complexities and large sparse system arise after discretizing the model equations are explained. We have designed a hybrid CPU/GPU solution of the proposed model by using Matlab. The parallel performance results show that CPU/GPU architecture is more efficient in large-scale problem simulations.

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DOI: 10.3217/jucs-025-09-1043

Authors: Andrey Fedorchenko, Elena Doynikova, Igor Kotenko

Abstract: Currently the problem of monitoring the security of information systems is highly relevant. One of the important security monitoring tasks is to automate the process of determination of the system weaknesses for their further elimination. The paper considers the techniques for analysis of vulnerability indexes and exploit source code, as well as their subsequent classification. The suggested approach uses open security sources and incorporates two techniques, depending on the available security data. The first technique is based on the analysis of publicly available vulnerability indexes of the Common Vulnerability Scoring System for vulnerability classification by weaknesses. The second one complements the first one in case if there are exploits but there are no associated vulnerabilities and therefore the indexes for classification are absent. It is based on the analysis of the exploit source code for the features, i.e. indexes, using graph models. The extracted indexes are further used for weakness determination using the first technique. The paper provides the experiments demonstrating an effectiveness and potential of the developed techniques. The obtained results and the methods for their enhancement are discussed.

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DOI: 10.3217/jucs-025-08-0967

Authors: Benjamin Weyers, Ekaterina Auer, Wolfram Luther

Abstract: We suggest to widen the focus of the scientific computations community from an isolated consideration of reliable numerical algorithms using standardized arithmetic to a broad user-centered system modeling and simulation approach relying on an appropriate verification and validation (V&V) design. Most V&V works rarely consider human-related issues specifically. However, modern applications generate and employ huge amounts of heterogeneous data and usually exhibit high complexity - challenges that are best tackled by augmenting human reasoning with automated techniques. That is, novel visual and collaborative approaches are needed to interpret the results, which has to be accounted for in the general V&V procedure. This should include an assessment of (meta-) data and code/outcome quality, selection of methods to propagate and bound uncertainty and, lastly, formally rigorous validation efforts. We present an approach to reliable visual analytics (i.e., analytics subjected to this V&V assessment), which can in turn contribute to the overall V&V procedure after that. Two use cases illustrate the potential of the introduced framework for reliable visual analytics.

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DOI: 10.3217/jucs-024-09-1330

Authors: Yujia Zhai, Kejun Qian, Fei Xue, Moncef Tayahi

Abstract: The spark-ignition (SI) engine dynamics is described as a severely nonlinear and fast process. A black-box model obtained by system identification approach is often valuable for the control and fault diagnosis application on such systems. Recurrent neural network (RNN) might be better suited for such dynamical system modelling due to its feedback back scheme if compared with feed-forward neural network. However, the computational load for RNN limits its practical application. In this paper, a diagonal recurrent neural network (DRNN) is investigated to model SI engine dynamics to achieve a balance between the modelling performance and computational burden. The data collection procedure and algorithms for training DRNN are presented too. Satisfactory results on modelling have been obtained with moderate cost on computation.

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DOI: 10.3217/jucs-024-09-1153

Authors: Ahyoung Choi, Hangsik Shin

Abstract: Recently, many studies have been conducted on how to manage and analyze various types of health data such as clinical data, genomic data, and wirelessly collected multiple sensory data. In this paper, we propose a web-based healthcare data integration and management platform that collects heterogeneous types of health-related medical record as well as real-time lifelogging data. This platform provides flexible architecture to different types of data exchanges. The platform manages real-time data such as heart rate, blood pressure, and activity information extracted from various healthcare devices and provides functions to transmit them to the server. Then it analyses the risk based on a domain knowledge and individual differences by applying machine learning tools, then visualizes the result to the patient and doctor dynamically based on information simplification method. It also controls the data access authority concerning the level of expertise and role. For evaluation of integrated data analysis, we apply open database and evaluate the proposed risk analyser result. The proposed platform could be utilized for future healthcare service to share accumulated healthcare data in various situations.

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DOI: 10.3217/jucs-024-04-0444

Authors: Kamil Książek, Karolina Kęsik, Zbigniew Marszałek

Abstract: Nowadays, identity verification support systems are becoming more and more popular. Machine learning is one of the leading fields of research from all over the world. However, each classifier needs a large number of samples to be properly trained. Preparing such samples proves to be a big problem for several reasons. One of them is the quality of the recording, another is the problem of feature extraction. In this work, the idea of processing sound samples by using their graphical representation in the form of spectrograms is described. The process removes specific, redundant information from the samples and then performs feature extraction. The proposed technique has been tested for identity verification using convolutional neural networks. The performed tests and obtained results have been described and discussed to indicate numerous advantages and disadvantages of the proposed technique.

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DOI: 10.3217/jucs-024-04-0372

Authors: A M N Balla Husamelddin, Guang Chen, Weipeng Jing

Abstract: While cloud systems deliver a larger amount of computing power, they do not guarantee full security and reliability. Focusing on improving successful job execution under resource constraints and security problems, this work proposes an enhanced, effective, integrated and novel approach to security and reliability. To apply a high level of security in the system, our novel approach uses cloud biometric authentication by splitting the biometric data into small chunks and spreading it over the cloud's resources. Reliability is enhanced through successful job execution by employing an adaptive reinforcement learning (RL) algorithm combined with a queuing theory. Our approach supports task schedulers to effectively adapt to dynamic changes in cloud environments. Based on the idea of reliability, we developed an adaptive action-selection, which controls the action selection dynamically by considering queue buffer size and the uncertainty value function. We evaluated the performance of our approach by several experiments conducted in terms of successful task execution and utilization rate and then compared our approach with other job scheduling policies. The experimental results demonstrated the efficiency of our method and achieved the objectives of the proposed system.

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DOI: 10.3217/jucs-023-10-0992

Authors: Cecilia Sanz, Veronica Artola, Andrea Guisen, Javier Marco, Eva Cerezo, Sandra Baldassarri

Abstract: In this article, we present an assessment process on a tangible interaction application oriented to individuals with complex communication needs, called ACoTI, and details about the main results obtained thus far. The process is based on a set of decisions that have been surveyed as key elements for assessing this type of experiences, based on a background review that was carried out. In addition to that, it has taken into account the contribution of key players from the special education field and it is the foundation for the user-centered and evolutionary design of the application. A number of findings and challenges that open up the door to keep contributing to this specific area was presented. For instance, creating an authoring tool that is available for the educators to be able to generate themselves customized activities for their students, considering the specific needs of each of them.

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DOI: 10.3217/jucs-023-10-0969

Authors: Alexandros Fakis, Georgios Karopoulos, Georgios Kambourakis

Abstract: While more and more users turn to IP-based communication technologies, privacy and anonymity remain largely open issues. One of the most prominent VoIP protocols for multimedia session management is SIP which, despite its popularity, suffers from security and privacy aws. As SIP messages are sent in plain text, user data are exposed to intermediate proxies and eavesdroppers. As a result, information about users participating in a call can leak from header data, which cannot be omitted since they are needed for the correct routing of SIP messages to their final destination. Even more, traffic analysis attacks can be mounted with data stemming from lower layers. To redress this kind of problems, privacy can be achieved either by the construction of a lower level tunnel (via the use of SSL or IPsec protocols) or by employing a customtailored solution. However, SSL and IPsec are known for leading to undesirable, non affordable delays, and thus the need for a SIP-oriented solution is preferable. In the context of this article, we evaluate three alternative solutions to encounter the above issues. More specifically, we use two well-known anonymity networks, Tor and I2P, for secluding both caller's and callee's actions by securing SIP messages content. As a third solution, we present our proposal for preserving privacy in SIP signaling, by using an onion-routing approach, where selected sensitive fields of SIP messages are encrypted using either asymmetric or symmetric encryption. We compare these three alternatives in terms of performance, mentioning the pros and cons that come up with each proposal. Our work also presents the reasons why other existing anonymity networks fail to be considered as appropriate for preserving anonymity in SIP.

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DOI: 10.3217/jucs-022-10-1398

Authors: Osmel Bordies, Yannis Dimitriadis

Abstract: Artifact flow represents an important aspect of teaching/learning processes, especially in CSCL situations in which complex relationships may be found. However, explicit modeling of CSCL processes with artifact flow may increase the cognitive load and associated effort of the teachers-designers and therefore decrease the efficiency of the design process. The empirical study, reported in this paper and grounded on mixed methods, provides evidence of the effort overload when teachers are involved in designing CSCL situations in a controlled environment. The results of the study illustrate the problem through the subjective perception of the participating teachers, complemented with objective parameters, such as time consumed, errors committed, uncertainty and objective complexity metrics.

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DOI: 10.3217/jucs-022-06-0836

Authors: Kazimierz Choroś, Jacek Topolski

Abstract: The paper describes and extensively evaluates a new method for the parameterized and intelligent generation of an infinite environment including various biomes in a virtual 3D space defined by the user. The biomes might be generated with different set of textures and by using different formulas to form shape of the landscape. Despite different shapes they still blend smoothly between each other. To achieve this goal Gaussian blur and Voronoi diagram algorithms are used. To enable additional parameterization for biomes placement the standard Voronoi algorithm is extended by including cell change along an axis and dispersion of Voronoi cells. Applying latitude into terrain type produces more realistic results. An entire terrain is generated on the CPU using a separate thread to eliminate stuttering during calculations and then the data is sent to the GPU in order to draw it. It forces reducing amount of data as much as possible, because data must be sent through the graphical bus. The tests have been performed by setting up a sample terrain and performing basic actions on this terrain like moving or rotating to gather frame times. The results showed that although the method demands much memory it is efficient and suitable for the real-time processing.

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DOI: 10.3217/jucs-022-03-0416

Authors: Jarosław Jankowski, Kostas Kolomvatsos, Przemysław Kazienko, Jarosław Wątróbski

Abstract: An important aspect of managing social platforms, online games and virtual worlds is the analysis of user characteristics related to subscriptions and virtual goods purchases. The results of such a process could be adopted in decision support applications that build on top of users' behavior provide efficient strategies for the virtual world's management. One of the research questions in this area is related to the factors affecting purchases and their relation to the activity within social networks as well as the ability to use past data to make reasoning about future behaviors. Complex online systems are hard to analyze when adopting legacy methodologies due to the huge amount of data generated by users' activity and changes in their behavior over time. In this paper, we discuss an analysis of the characteristics of users performing purchases for virtual products. We adopt a Neuro-Fuzzy system which has the ability to process data under uncertainty towards better decisions related to parameterization of the virtual retail system. The proposed Fuzzy Logic (FL) inference model focuses on the analysis of purchases based on the types of past transactions and social activity as inputs. The proposed system results values for specific parameters affecting/depicting users’ behavior like own purchases, gifting and virtual products usage as output. Our results could be adopted for decision support of online platform operators and show the relations between less and more experienced users in terms of frequency and value of purchases, engagement with the use of virtual goods and gifting behaviors. Models based on the social activity with distinguished inbound and outbound social connections show increased interest in virtual goods among users with a higher number of inbound connections as a possible tool for building social position.

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DOI: 10.3217/jucs-021-07-0959

Authors: Andreea Molnar, Cristina Muntean

Abstract: When using mobile phones for learning purpose, video content is considered to be the preferred type of multimedia content. However, the video file has a big size in comparison to text or audio and might lead to a high delivery cost when transmitted over a mobile network, a cost that not all users are willing to pay. Concerns regarding the monetary cost for accessing data content through mobile networks have been raised by various researchers. A solution that considers the user preference for trading off between video quality and price in order to reduce the content delivery cost is presented. This paper also evaluates the proposed solution and presents the results of an experimental study that assesses the video content adaptation impact on information assimilation. The results show that although video quality is reduced information assimilation is not negatively affected by the adaptation. This holds true regardless of the mobile device used in the study.

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DOI: 10.3217/jucs-020-15-2016

Authors: Atif Alamri, Ghulam Muhammad, Abdulhameed A. Al Elaiwi, Khalid Al-Mutib, M. Hossain

Abstract: The increasing demand for ubiquitous access to technology enhanced learning environment has faced a challenge of heterogeneity in terms of networks, mobile device, platforms and finally, the learning content in various formats. In order to alleviate the challenge of the said diversity, content adaptation is essential. However, because of the diversity of the mobile users, networks and the rich media learning content, it is a major challenge for the access of learning content by the desired devices in the mobile learning environment. In order to alleviate the challenge of learning content mismatch, content adaptation is essential. This paper describes a content adaptation framework for mobile e-learning.

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DOI: 10.3217/jucs-020-13-1829

Authors: Xiuwen Fu, Wenfeng Li, Giancarlo Fortino, Pasquale Pace, Gianluca Aloi, Wilma Russo

Abstract: Opportunistic networks, as representative networks evolved from social networks and Ad-hoc networks, have been on cutting edges in recent years. Many research efforts have focused on realistic mobility models and cost-effective routing schemes. The concept of "community", as one of the most inherent attributes of opportunistic networks, has been proved to be very helpful in simulating mobility traces of human society and selecting suitable message forwarders. This paper proposes an interest-driven community-based mobility model by considering location preference and time variance in human behavior patterns. Based on this enhanced mobility model, a novel two-layer routing algorithm, named InterCom, is presented by jointly considering utilities generated by users' activity degree and social relationships. The results, obtained throughout an intensive simulation analysis, show that the proposed routing scheme is able to improve delivery ratio while keeping the routing overhead and transmission delay within a reasonable range with respect to well-known routing schemes for opportunistic networks.

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DOI: 10.3217/jucs-020-13-1712

Authors: Nelson Baloian, Diego Aguirre, Gustavo Zurita

Abstract: One of the main tasks in developing distributed collaborative systems is to support synchronization processes. The Coupled Objects paradigm has emerged as a way to easily support these processes by dynamically coupling arbitrary user interface objects between heterogeneous applications. In this article we present an architecture for developing distributed collaborative applications using HTML5 and show its usage through the design and implementation of a series of collaborative systems in different scenarios. The experience of developing and using this architecture has shown that it is easy to use, robust and has good performance.

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DOI: 10.3217/jucs-019-18-2677

Authors: Jaime Sánchez, Marcia Campos

Abstract: This study presents the development of a video game with audio and haptic interfaces that allows for the stimulation of orientation and mobility skills in people who are blind through the use of virtual environments. We evaluate the usability and the impact of the use of an audio and haptic-based videogame on the development of orientation and mobility skills in school-age learners who are blind. The results show that the interfaces used in the videogame are usable and appropriately designed, and that the haptic interface is as effective as the audio interface for orientation and mobility purposes.

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DOI: 10.3217/jucs-019-17-2617

Authors: Haris Papagiannakis, Margherita Antona, Stavroula Ntoa, Constantine Stephanidis

Abstract: This paper reports the design, development and evaluation of a technological framework for learning applications, named AmI Playfield, aimed at creating challenging learning conditions through play and entertainment. AmI Playfield is an educative Ambient Intelligent (AmI) environment which emphasizes the use of kinesthetic and collaborative technology in a natural playful learning context and embodies performance measurement techniques. In order to test and assess AmI Playfield, the "Apple Hunt" application was developed, which engages (young) learners in arithmetic thinking through kinesthetic and collaborative play, observed by unobtrusive AmI technology behind the scene. "Apple Hunt" has been evaluated according to a combination of methodologies suitable for young testers, whereas Children Committees are introduced as a promising approach to evaluation with children. The obtained results demonstrate the system's high potential to generate thinking and fun, deriving from the learners' full-body kinesthetic play and team work.

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DOI: 10.3217/jucs-019-17-2503

Authors: Ana Bernardos, Luca Bergesio, Josue Iglesias, José Casar

Abstract: In this paper, we exploit the capabilities of mobile devices as instruments to facilitate interaction in spaces populated with smart objects. We do this through MECCANO, a framework that supports an interaction method for a user to perform physical discovery and versatile configuration of behaviors involving a network of smart objects. Additionally, MECCANO guides the developer to easily integrate new augmented objects in the smart ecosystem. Behaviors are rule-based micro-services composed by a combination of events, conditions and actions that one or more smart objects can trigger, detect or perform. Each object owns and publishes its capabilities in a software module; this module becomes available when a user physically lies in the area of influence of the smart object. The capabilities provided by a specific object can be merged with those in other objects (including those in the user's mobile device itself) to configure a behavior involving several objects, adapted to the user's needs. On operation, the behavior is run within the mobile device, serving the device as orchestrator of the involved objects. The framework also facilitates sharing micro-services in such a way that users can act as prosumers by generating their self-made behaviors. New behaviors are associated to the classes of objects that are needed to execute them, becoming ready for other users to download. The proposed interaction method and its tools are demonstrated both from the developer's and the end-user's points of view, through practical implementations.

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DOI: 10.3217/jucs-019-16-2472

Authors: Dongjin Choi, Jeongin Kim, Xeufeng Piao, Pankoo Kim

Abstract: Social networking services (SNSs) such as Twitter and Facebook can be considered as new forms of media. Information spreads much faster through social media than any other forms of traditional news media because people can upload information with no time and location constraints. For this reason, people have embraced SNSs and allowed them to become an integral part of their everyday lives. People express their emotional status to let others know how they feel about certain information or events. However, they are likely not only to share information with others but also to unintentionally expose personal information such as their place of residence, phone number, and date of birth. If such information is provided to users with inappropriate intentions, there may be serious consequences such as online and offline stalking. To prevent information leakages and detect spam, many researchers have monitored e-mail systems and web blogs. This paper considers text messages on Twitter, which is one of the most popular SNSs in the world, to reveal various hidden patterns by using several coefficient approaches. This paper focuses on users who exchange Tweets and examines the types of information that they reciprocate other's Tweets by monitoring samples of 50 million Tweets which were collected by Stanford University in November 2009. We chose an active Twitter user based on "happy birthday" rule and detecting their information related to place to live and personal names by using proposed coefficient method and compared with other coefficient approaches. As a result of this research, we can conclude that the proposed coefficient method is able to detect and recommend the standard English words for non-standard words in few conditions. Eventually, we detected 88,882 (24.287%) more name included Tweets and 14,054 (3.84%) location related Tweets compared by using only standard word matching method.

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DOI: 10.3217/jucs-019-15-2320

Authors: Karol Rástočný, Michal Tvarožek, Maria Bielikova

Abstract: Information seeking on the Web has become day-to-day routine for more than two billion human beings most of who use traditional keyword-based search engines. Developers of these search engines stress personalization, prediction of users' next actions and mistake correction. But they are still struggling with results presentation and support for users, who make atypical queries or who do not exactly know what they are looking for. We address these issues via a novel approach for exploring web repositories, which naturally combines user search activities - look up, learning and investigation. We achieve this via view-based navigation in hierarchical clusters and two-dimensional graphs of search results.

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DOI: 10.3217/jucs-019-13-1986

Authors: Maurizio Vincini, Domenico Beneventano, Sonia Bergamaschi

Abstract: In the last twenty years, many data integration systems following a classical wrapper/mediator architecture and providing a Global Virtual Schema (a.k.a. Global Virtual View - GVV) have been proposed by the research community. The main issues faced by these approaches range from system-level heterogeneities, to structural syntax level heterogeneities at the semantic level. Despite the research effort, all the approaches proposed require a lot of user intervention for customizing and managing the data integration and reconciliation tasks. In some cases, the effort and the complexity of the task is huge, since it requires the development of specific programming codes. Unfortunately, due to the specificity to be addressed, application codes and solutions are not frequently reusable in other domains. For this reason, the Lowell Report 2005 has provided the guideline for the definition of a public benchmark for information integration problem. The proposal, called THALIA (Test Harness for the Assessment of Legacy information Integration Approaches), focuses on how the data integration systems manage syntactic and semantic heterogeneities, which definitely are the greatest technical challenges in the field. We developed a Data Transformation System (DTS) that supports data transformation functions and produces query translation in order to push down to the sources the execution. Our DTS is based on MOMIS, a mediator-based data integration system that our research group is developing and supporting since 1999. In this paper, we show how the DTS is able to solve all the twelve queries of the THALIA benchmark by using a simple combination of declarative translation functions already available in the standard SQL language. We think that this is a remarkable result, mainly for two reasons: firstly to the best of our knowledge there is no system that has provided a complete answer to the benchmark, secondly, our queries does not require any overhead of new code.

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DOI: 10.3217/jucs-019-12-1736

Authors: Miloš Ljubojević, Vojkan Vasković, Dušan Starčević

Abstract: Internet video advertising is a sensitive application regarding the quality of the multimedia content, efficiency of displayed advertisement and user's attention. Therefore, video advertising have to be described with respect to Quality of Experience (QoE). Important issue represents trade-off between the Quality of Experience and ad efficiency. The analysis of payment which takes into account the duration of video ad is one of the aspects in this research. This paper analyzes influences of the format of the video ad to user's attention in order to achieve optimum ratio between the efficiency of the ad and QoE. We investigated impact of the position of the video ad in video content, ad duration and transition effects in merging video contents to the user's attention and ad efficiency. The model for estimation of QoE, taking into account improvement efficiency of video ad, was presented and metrics which are necessary for the evaluation of the QoE are introduced. The results show that it is possible to design video ad to achieve optimal ratio between the efficiency of ad and QoE. The improvement of the efficiency of an ad may be achieved while retaining the maximum QoE at the same time.

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DOI: 10.3217/jucs-019-08-1175

Authors: Amandeep Dhir, Mohammed Al-Kahtani

Abstract: Mobile Augmented Reality (MAR) blends the real world with digital objects especially in ubiquitous devices such as smartphones. The MAR applications provide an intelligent interface for users. In this, valuable digital information is advertised in physical spaces. However, the success of these applications is tied directly to the degree of user acceptance. This makes understanding the needs and expectations of the MAR's potential users of paramount importance for designing and building the proper application. The objective of the paper is to expose an important gap in the development of novel applications in the virtual world. Previous research has shown that it is essential to study and understand the needs and expectations of the potential users of the upcoming application or system. Studying user needs and expectations before offering the developed application ensures a minimum level of acceptance and, of course, success. This paper presents a detailed study comprising of a user-experience (UX) evaluation of different prototypes through the use of three different UX evaluation methods. This kind of evaluation allows new developments to offer systems, which do not fail. The main contributions of this study are that it: 1) solicits expectations when consumers use MAR applications, 2) assesses the UX over different prototypes using three different metrics, 3) provides methodological insights on UX evaluation experiments and, 4) is useful for anyone who wants to develop handheld applications after understanding user expectations and how his experience should progress. The results of the study show that users value concreteness, realizability, personalization, novelty, intuitiveness and the usefulness of presented information. Paying attention to these factors can help develop more acceptable MAR applications and lead to more novel future designs.

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DOI: 10.3217/jucs-019-08-1140

Authors: Valeria Herskovic, Carolina Fuentes, Richard Ibarra, Javier Bustos-Jiménez

Abstract: Many users nowadays work with multiple heterogeneous computing devices, such as desktop computers, tablets, laptops and mobile phones. Transferring files between devices is cumbersome and usually done through the internet (e.g. email or cloud computing services) or physical devices such as flash drives. Some solutions for this problem have been proposed, however, they do not allow efficient and easy transferring of several files over medium distances. To facilitate file transfer between different devices, we implemented an augmented-reality based smartphone application that uses "pick-and-drop" and "drag-and-drop" mechanisms to transfer files between devices. This paper presents the implementation and evaluation of the interaction technique, called pick and drag and drop. This technique has two central contributions: it allows transferring several files at once, and it allows file transfer over greater distances than existing alternatives. The technique was tested in two laboratory experiments with promising results: time taken to transfer files was similar to other options, and 78% of users declared preferring PDD to alternative methods.

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DOI: 10.3217/jucs-018-18-2576

Authors: Pilar Sancho, Javier Torrente, Baltasar Fernández-Manjón

Abstract: The use of Multi-User Virtual Environments (MUVEs) is a trend topic in virtual education and e-learning. A number of research papers and literature reviews addresses how digital natives learn in a different way than the previous generation and how these kinds of highly interactive environments may positively affect their motivation. But actual efficacy of MUVEs to enhance students' motivation has not been deeply backed up yet by empirical research. This paper contributes with a small experiment conducted on an elective programming course for engineering students. The hypothesis was that the use of a MUVE would improve students' motivation towards learning. To evaluate the veracity of this hypothesis, the dropout rates of the course were compared alongside four academic years, assuming that lower dropout rates imply a motivation increase. The first two years (Y1 and Y2) a traditional approach based on lectures, weekly assignments and a final exam was used. The last two years (Y3 and Y4), the NUCLEO approach was used. NUCLEO is a pedagogical strategy that combines game mechanics (including collaboration and competition), problem-based learning and a fantastic narrative metaphor. In Y3 the NUCLEO approach was implemented having a flat classical interface provided by the standard Moodle Learning Management System (LMS), while in Y4 a ·3D MUVE was used as interface. Dropouts during the traditional teaching period (Y1-2) fell dramatically during the NUCLEO teaching period (Y3-4). However, dropouts were higher in Y4 when a MUVE was used as interface (16.66%) compared to Y3 (9.09%). These data suggest that just using a MUVE or a 3D environment can enhance motivation but to achieve maximum effectiveness if they are combined with elements like game mechanics. These data were also backed up by satisfaction questionnaires fulfilled by teachers and students.

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DOI: 10.3217/jucs-018-18-2516

Authors: David Griol, José Molina, Araceli De Miguel, Zoraida Callejas

Abstract: Social Networking has been a global consumer phenomenon during the last few years. Online communities are changing the way people behave, share and interact within their daily lives. Most of such communities are mainly focused on sharing contents and communicating using a traditional web interface. However, social virtual worlds are computer-simulated environments that the users can "inhabit" and in which they can interact and create objects. Education is one of the most interesting applications of virtual worlds, as their flexibility can be exploited in order to create heterogeneous groups from all over the world who can collaborate synchronously in different virtual spaces. In this paper, we highlight the potential of virtual worlds as an educative tool and propose a model to create learning environments within Second Life or OpenSimulator combining the Moodle learning management system, embodied conversational metabots, and programmable 3D objects. We have implemented the proposal in a learning system for several subjects of the Computer Science degree in our university and show that it fostered engagement and collaboration and helped the students to better understand complex concepts.

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DOI: 10.3217/jucs-018-15-2120

Authors: Nikolaos Avouris, Nikoleta Yiannoutsou

Abstract: In this paper we review mobile location-based games for learning. These games are played in physical space, but at the same time, they are supported by actions and events in an interconnected virtual space. Learning in these games is related to issues like the narrative structure, space and game rules and content that define the virtual game space. First, we introduce the theoretical and empirical considerations of mobile location based games, and then we discuss an analytical framework of their main characteristics through typical examples. In particular, we focus on their narrative structure, the interaction modes that they afford, their use of physical space as prop for action, the way this is linked to virtual space and the possible learning impact the game activities have. Finally we conclude with an outline of future trends and possibilities that these kinds of playful activities can have on learning, especially outside school, like in environmental studies and visits in museums and other sites of cultural and historical value.

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DOI: 10.3217/jucs-018-12-1721

Authors: Sipho Ngobeni, Hein Venter, Ivan Burke

Abstract: Over the past decade, wireless mobile communication technology based on the IEEE 802.11 Wireless Local Area Networks (WLANs) has been adopted worldwide on a massive scale. However, as the number of wireless users has soared, so has the possibility of cybercrime. WLAN digital forensics is seen as not only a response to cybercrime in wireless networks, but also a means to stem the increase of cybercrime in WLANs. The challenge in WLAN digital forensics is to intercept and preserve all the communications generated by the mobile stations and to conduct a proper digital forensic investigation. This paper attempts to address this issue by proposing a wireless digital forensic readiness model designed to monitor, log and preserve wireless network traffic for digital forensic investigations. Thus, the information needed by the digital forensic experts is rendered readily available, should it be necessary to conduct a digital forensic investigation. The availability of this digital information can maximise the chances of using it as digital evidence and it reduces the cost of conducting the entire digital forensic investigation process.

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DOI: 10.3217/jucs-018-12-1628

Authors: Rahul Rastogi, Rossouw Solms

Abstract: Information security culture has been found to have a profound influence on the compliance of end-users to information security policies and controls in their organization. Similarly, a complementary aspect of information security is the culture of information security managers and developers in the organization. This paper calls this is as the 'information security service culture' (ISSC). ISSC shapes and guides the behaviour of information security managers and developers as they formulate information security policies and controls. Thus, ISSC has profound influence on the nature of these policies and controls and thereby on the interaction of end-users with these artefacts. ISSC is useful in transforming information security managers and developers from their present-day technology-focused approach to an end-user centric approach.

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DOI: 10.3217/jucs-018-09-1177

Authors: Xingang Liu, Jiantan Liu, Kook-Yeol Yoo, Haengrae Cho

Abstract: For the Wireless Multimedia Sensor Network (WMSN), the intraframe video coding is widely used for the robust transmission and computation complexity. Though the intraframe algorithm requires much smaller computational complexity than the interframe coding, the amount of computation of the intraframe should be reduced to use WMSN application. In this paper, we propose an intra mode decision algorithm to reduce the computation complexity of intraframe H.264/AVC encoders. The proposed algorithm determines the candidate modes and skips the remaining modes based on the smoothness and directional similarity of MB. The simulation results show that the proposed algorithm achieves 18% to 70% reduction in the computational complexity, compared with the various conventional methods.

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DOI: 10.3217/jucs-018-05-0704

Authors: Mabel Vazquez-Briseno, Pierre Vincent, Juan Nieto-Hipolito, Juan Sanchez-Lopez

Abstract: The development of mobile applications and services has led to new challenges for software programmers. One of the main differences from standard PC programming is that the mobile environment is still limited in several aspects. Thus, there are many applications for mobile devices that share similarities, and implementing new applications may result in duplicated code within the same project or in similar projects. Moreover, current mobile development is still an error-prone task that may produce difficult-to-maintain applications. As a result, developers need new tools to help them to develop mobile software efficiently. This work focuses on a new framework for generating mobile applications and services, MobAppGen. The framework provides a set of components called modules that can be used to construct new applications using a Web interface. The architecture and functionalities of the framework are delineated, and several tests were conducted to evaluate the performance of the framework. For the tests, we created a number of projects using the available modules. In addition, a survey was conducted to estimate the acceptance and usefulness of the framework.

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DOI: 10.3217/jucs-018-05-0676

Authors: Ahmed Nait-Sidi-Moh, Mohamed Bakhouya, Wafaa Ait-Cheik-Bihi, Jaafar Gaber

Abstract: Distributed systems become ubiquitous by allowing users access to a wide range of services at any time, anywhere, and from a variety of devices. In these open environments where there are many opportunities for both fraudulent services and misbehaving clients, service discovery systems are subject to security challenges. Controlling services' access is one of the fundamental issues that must be faced in the context of service discovery in distributed and open environments. Therefore, secure accesses and utilization of available services must be ensured for users. In our previous work, a contract-based approach for controlling the service access in a distributed computing context was presented. In this paper, we address the purpose and the usage of digital signature on negotiated electronic queries between a server and clients in service discovery systems and web service composition. The paper discusses the combined use of Timed Event Graphs and (max, +)- algebra to model, evaluate and optimize the performance of the signature process and client requests validation by a service provider (server). Based on an optimization resource allocation algorithm, an improvement study of the quality of service offered to the clients, in terms of waiting times and validation of their requests, is proposed. The results are reported and show the efficiency of the use of the proposed formal tools for performance analysis, evaluation and tuning of the considered process.

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DOI: 10.3217/jucs-018-03-0314

Authors: Stefan Minder, Michele Notari, Felix Schmitz, Rainer Hofer, Ulrich Woermann

Abstract: The Medical Faculty of the University of Bern uses voice-over in picture driven e-learning modules to avoid split attention induced by the modality effect. To lower production costs, professional narrators have been replaced by computer-generated voices. The e-learning modules are produced with a content management system (CMS) offering text-to-speech functionality. 107 Swiss high school students passed a 20-minute e-learning sequence on cystic fibrosis. In a nested between-group design with four learning content presentation modalities (written text vs. human voice-over vs. artificial voice-over plus 15"-laptop-screens vs. 2,8"smart-phone screens), the learning outcome was assessed at three points in time: before, just after, and six weeks after the learning phase. All modalities led to significant short-term and long-term increase in factual knowledge about cystic fibrosis. Our two hypotheses are supported: (1) presenting pictures with both human and artificial voice-over leads to the same factual learning outcome, and (2) the e-learning module leads to the same learning outcome and acceptance independent of devices and their screen sizes. Furthermore, the image-voice-over modality on mobile devices (small screens) turned out to be a setting with no significant difference in effectiveness.

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DOI: 10.3217/jucs-018-02-0264

Authors: Joaquin Olivares

Abstract: This paper presents an architecture which is capable of processing variable block size motion estimation (VBSME) and which is able to apply pixel precision reduction techniques in a reconfigurable way. The design has been carried out by using online arithmetic, which allows to process all motion vectors of a block in just one iteration. The system has been implemented on FPGA and just requires 7724 slices, reaching a performance of 55 4CIF frames per second (fps) in full precision and of 72 with 4 bit precision. Results for different search areas 31 x 31, 32 x 32, and 46 x 46 are presented. Using 4bit precision real time processing for HDTVp is achieved. Thanks to the reduced cost and high performance, this architecture is perfect for mobile devices.

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DOI: 10.3217/jucs-018-01-0044

Authors: Peter Sloep, Adriana Berlanga, Wolfgang Greller, Slavi Stoyanov, Marcel Van Der Klink, Symeon Retalis, Jan Hensgens

Abstract: Professional Development is ill served by traditional ways of learning. It can profit from a Learning Networks approach, which emphasizes logistic, content and didactic flexibility. Learning Networks are online, social networks that have been designed and tooled to foster informal learning. Three European projects are discussed - idSpace, LTfLL, Handover - which have developed tools befitting networked learning. Each in its own way, the projects illustrate the benefits of a networked learning approach. This goes for all three flexibilities but in particular for the need to be didactically flexible. Finally, it is argued that formal education could profit from the tools discussed.

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DOI: 10.3217/jucs-017-04-0605

Authors: Peter Schultes, Franz Lehrer, Harald Kosch

Abstract: Interactive video is increasingly becoming a more and more dominant feature of our media platforms. Especially due to the popular YouTube annotations framework, integrating graphical annotations in a video has become very fashionable these days. However, the current options are limited to a few graphical shapes for which the user can define as good as no dynamic behaviour. Despite the enormous demand for easy-creatable, interactive video there are no such advanced tools available. In this article we describe an innovative approach, to realize dynamics and interactivity of video annotations. First we explain basic concepts of video-markup like the generic element model and visual descriptors. After that we introduce the event-tree model, which can be used to define event-handling in an interactive video formally as well as visually. By combining these basic concepts, we can give an effective tool to the video community for realizing interactive and dynamic video in a simple, intuitive and focused way.

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DOI: 10.3217/jucs-016-21-3314

Authors: Gerhard Wurzinger

Abstract: Due to information technologies the problem we are facing today is not a lack of information but too much information. This phenomenon becomes very clear when we consider two figures that are often quoted: Knowledge is doubling in many fields (biology, medicine, computer science, ...) within some 6 years; yet information is doubling every 8 months! This implies that the same piece of information/knowledge is published a large number of times with small variations. Just look at an arbitrary news item. If considered of some general interest reports of it will appear in all major newspapers, journals, electronic media, etc. This is also the problem with information portals that tie together a number of large databases. It is our contention that we need methods to reduce the huge set of information concerning a particular topic to a number of pieces of information (let us call each such piece an "essay" in what follows) that present a good cross-section of potential points of view. We will explain why one essay is usually not enough, yet the problem of reducing a huge amount of contributions to a digestible number of essays is formidable, indeed is science fiction at the moment. We will argue in this paper that it is one of the important tasks of computer sciences to start tackling this problem, and we will show that in some special cases partial solutions are possible.

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DOI: 10.3217/jucs-016-16-2214

Authors: Hermann Stern, Rene Kaiser, Philip Hofmair, Peter Kraker, Peter Kraker, Stefanie Lindstaedt, Peter Scheir

Abstract: One of the success factors of Work Integrated Learning (WIL) is to provide the appropriate content to the users, both suitable for the topics they are currently working on, and their experience level in these topics. Our main contributions in this paper are (i) overcoming the problem of sparse content annotation by using a network based recommendation approach called Associative Network, which exploits the user context as input; (ii) using snippets for not only highlighting relevant parts of documents, but also serving as a basic concept enabling the WIL system to handle text-based and audiovisual content the same way; and (iii) using the Web Tool for Ontology Evaluation (WTE) toolkit for finding the best default semantic similarity measure of the Associative Network for new domains. The approach presented is employed in the software platform APOSDLE, which is designed to enable knowledge workers to learn at work.

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DOI: 10.3217/jucs-016-10-1368

Authors: Farag Azzedin

Abstract: The ever growing explosion in technological advancements is paving the way to the expansion of multimedia applications. Unfortunately, current multimedia applications use centralized architectures. Before decentralized architectures are utilized and used, some issues related to decentralization must be addressed. In this paper, we focus on the problem of free riding in decentralized collaborative environments. We propose a novel taxonomy of free riders in multimedia systems based on trustworthiness. To the best of our knowledge, no existing literature considers trustworthiness, which we believe is a vital dimension that should be considered when identifying free riders. We also propose a new mechanism to filter out and isolate free riders. Our extensive simulation experiments show that our proposed algorithm is reasonably successful in identifying free riders in multimedia-based systems.

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DOI: 10.3217/jucs-016-01-0140

Authors: Zhang Mingyi, Li Danning, Zhang Ying

Abstract: Classical classification and clustering based on equivalence relations are very important tools in decision-making. An equivalence relation is usually determined by properties of objects in a given domain. When making decision, anything that can be spoken about in the subject position of a natural sentence is an object, properties of which are fundamental elements of the knowledge of the given domain. This gives the possibility of representing the concept related to a given domain. In general, the information about a set of the objects is uncertain or incomplete. Various approaches representing uncertainty of a concept were proposed. In particular, Zadeh?s fuzzy set theory and Pawlak?s rough set theory have been most influential on this research field. Zadeh characterizes uncertainty of a concept by introducing a membership function and a similarity (fuzzy equivalence) relation of a set of objects. Pawlak then characterizes uncertainty of a concept by union of some equivalence classes of an equivalence relation. As one of particular important and widely used binary relations, equivalence relation plays a fundamental role in classification, clustering, pattern recognition, polling, automata, learning, control inference and natural language understanding, etc.  An equivalence relation is a binary relation with reflexivity, symmetry and transitivity. However, in many real situations, it is not sufficient to consider equivalence relations only. In fact, a lot of relations determined by the attributes of objects do not satisfy transitivity. In particular, information obtained from a domain of objects is not transitive, when we make decision based on properties of objects. Moreover, the information about symmetry of a relation is mostly uncertain. So, it is needed to approximately make decision and reasoning by indistinct concepts. This provokes us to explore a new class of relations, so-called class of fuzzy semi-equivalence relations. In this paper we introduce the notion of fuzzy semi-equivalence relations and study its properties. In particular, a constructive method of fuzzy semi-equivalence classes is presented. Applying it we present approaches to the fuzzyfication of indistinct concepts approximated by fuzzy relative and semi-equivalence classes, respectively. And an application of the fuzzy semi-equivalence relation theory to generate decision rules is outlined.

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DOI: 10.3217/jucs-015-18-3364

Authors: Gabriel Pereira e Silva, Rafael Lins, Brenno Miro, Steven Simske, Marcelo Thielo

Abstract: Portable digital cameras are being used widely by students and professionals in different fields as a practical way to digitize documents. Tools such as PhotoDoc enable the batch processing of such documents, performing automatic border removal and perspective correction. A PhotoDoc processed document and a scanned one look very similar to the human eye if both are in true color. However, if one tries to automatically binarize a batch of documents digitized from portable cameras compared to scanners, they have different features. The knowledge of their source is fundamental for successful processing. This paper presents a classification strategy to distinguish between scanned and photographed documents. Over 16,000 documents were tested with a correct classification rate of over 99.96%.

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DOI: 10.3217/jucs-015-11-2225

Authors: Kleinner Oliveira, Karin Breitman, Toacy Oliveira

Abstract: In this paper we discuss the importance of model comparison as one of the pillars of model-driven development (MDD). We propose an innovative, flexible, model comparison approach, based on the composition of matching strategies. The proposed approach is fully implemented by a match operator that combines syntactical matching rule, synonym dictionary and typographic similarity strategies to a semantic, ontology-based strategy. Ontologies are semantically richer, have greater power of expression than UML models and can be formally verified for consistency, thus providing more reliability and accuracy to model comparison. The proposed approach is presented in the format of a workflow that provides clear guidance to users and facilitates the inclusion of new matching strategies and evolution.

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DOI: 10.3217/jucs-015-10-2078

Authors: Elhadi Shakshuki, Richard Halliday

Abstract: Studying and understanding algorithms is important for all computer scientists. Over two decades of research has been devoted to improving algorithm visualization and algorithm explanation techniques. Knowledge gained from these practices allows us to design and implement logically correct programs with considerations to runtime and memory constraints. For many students, learning algorithms in a traditional manner (i.e. using text-books) is challenging. We have developed an alternative approach to teaching algorithms called the Structured Hypermedia Algorithm Explanation (SHALEX) system, which uses hypermedia and represents algorithms as an abstract tree structure. Although SHALEX is a fully functioning teaching tool, currently it does not provide a way of receiving feedback on student’s progress. To address this problem, this paper extends SHALEX with intelligent agent to monitor student progress, to provide the student with hints where necessary and to record the results of student interaction, all of which provide a means of quantifying the level of understanding the student has achieved. The system is implemented as a web-based application using the client-server architecture. This allows students to learn algorithms through both distance education and in the classroom setting.

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DOI: 10.3217/jucs-015-09-2011

Authors: Ting Peng, Qinghua Zheng, Yinli Jin

Abstract: In Peer-to-Peer(P2P) streaming system, the multicasting tree construction method influences considerably on network load. Under current available strategies, network resources are not used economically, or network resource friendship and the flexibility can't be approached thoroughly. With the increasing application of Internet, network infrastructure itself becomes a precious resource, which should be performed effectively. In our implementation, network transmission delay between the peers is detected, used as practical performance metrics of the P2P streaming system. According to the metrics, network friendly tree is provided as overlay multicasting tree construction strategy for P2P streaming system. In this strategy, additional transmission delays are minimized as new peers enter. The simulation experiment presents that the proposed strategy network friendly tree works better than other contrasts. And the transmission performance improves significantly at minor additional cost.

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DOI: 10.3217/jucs-015-08-1589

Authors: Junseok Hwang, Youngjin Lee, Seunghyun Kim

Abstract: Weblogs have received attention as new, personalized media. Yet, only few of them attract public attention and become successful. This study explores weblog success factors in three categories: content creation, content features and content diffusion. During the process of content creation in weblogs, we argue that weblog service providers (WSPs) support bloggers’ resource collection. We also presume that the volume or the quality of posts in weblogs could be matter to gain visitors’ attention when weblog content (i.e., post) is generated. During the process of content diffusion, we assume that use of blogging technologies (BTs) such as trackback or RSS would enhance content-sharing activities between weblogs. Based on the data from a sample of Korean individual weblogs, our analysis indicates that weblog success (in terms of the number of unique visitors per week) is related to the WSP’s support level for content creation as well as content features.

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DOI: 10.3217/jucs-015-05-1119

Authors: Naixue Xiong, Jing He, Jong Park, Donald Cooley, Yingshu Li

Abstract: Pervasive smart computing environments make people get accustomed to convenient and secure services. The overall goal of this research is to classify vehicles along the I215 freeway in Salt Lake City, USA. This information will be used to predict future roadway needs and the expected life of a roadway. The classification of vehicles will be performed by a synthesis of multiple sets of features. All feature sets have not yet been determined; however, one such set will be the reduced wavelet transform of the image of a vehicle. In order to use such a feature, it is necessary that the image be normalized with respect to size, position, and so on. For example, a car in the right most lane in an image will appear smaller than one in the left most lane, because the right most lane is closest to the camera. Likewise, a vehicle’s size will vary depending on where in a lane its image is captured. In our case, the image capture area for each lane is approximately 100 feet of roadway. A goal of this paper is to normalize the image of a vehicle so that regardless of its lane or position in a lane, the features will be approximately the same. The wavelet transform itself will not be used directly for recognition. Instead, it will be input to a neural network and the output of the neural network will be one element of the feature set used for recognition.

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DOI: 10.3217/jucs-015-05-1065

Authors: Jong Park

Abstract: Ubi-Com has emerged as an exciting new paradigm to provide intelligent computig and communications at anytime and anywhere. But, In order to take the advantages of such services, it is important that intelligent security framework be suitable for Ubi-Com. In this paper, we propose privacy and access control scheme by surveillance which is one of core security technologies for ubiquitous hybrid intelligent security framework. In this scheme, the device information and the signature information can be added to the image data obtained by the image capturing device to maintain security of the image data and use the image data as digital proof when a specific event is generated.

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DOI: 10.3217/jucs-015-05-1023

Authors: Shiguo Lian, Yan Zhang

Abstract: Normally, the multimedia content provider and network service providers are separated in mobile TV systems. The TV programs are broadcasted from the content provider to the mobile terminals through Digital Video Broadcasting Transmission System for Handheld Terminals (DVB-H), and the access information is unicasted from the service provider to the user via General Packet Radio Services (GPRS) networks. Due to the network architecture heterogeneity, protocols variation and algorithms difference, securing mobile TV content is becoming a significant challenge. In this paper, we present the architecture, protocol, user identification and digital right management (DRM) for protecting mobile TV multimedia content. The network architecture describes the integrated DVB-H and GPRS to provide secure mobile TV services. The efficient protocols and algorithms are proposed to encrypt the content and also decrypt the coded content. The user identification is able to identify the legal user by matching the username-password pair or the scanned fingerprint. The DRM is able to protect the data from both DVB-H and GPRS. Following this framework, the illegal usage of the mobile TV services can be efficiently prevented and the real-time multimedia Quality-of-Service (QoS) with respect to delay can be guaranteed. The real implementation has demonstrated the effectiveness of the multimedia content protection in the heterogeneous mobile networks. In addition, the delay is sufficiently low to provide live TV.

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DOI: 10.3217/jucs-015-03-0678

Authors: Martin Memmel, Michael Kockler, Rafael Schirru

Abstract: In today's information environments, tagging is widely used to provide information about arbitrary types of digital resources. This information is usually created by end users with different motivations and for different kinds of purposes. When aiming to support users in the tagging process, these differences play an important role. In this paper several approaches to generate tag recommendations are discussed, and a prototypical recommender system for the social resource sharing platform ALOE is presented. This interactive system allows users to control the generation of the recommendations by selecting the sources to be used as well as their impact. The component was introduced at DFKI, and a first evaluation showed that the recommender component was considered as helpful by a majority of users.

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DOI: 10.3217/jucs-015-02-0426

Authors: Jinwei Wang, Jianmin Lü, Shiguo Lian, Guangjie Liu

Abstract: At present, the proposed authentication schemes can be classified into three categories. The first category is the watermarking authentication schemes in which the watermark is independent of the multimedia content. The second category is the signature-based authentication schemes in which the signature is generated by the multimedia content and is not embedded into the multimedia content. The third category is the content-based watermarking authentication schemes in which the watermark is generated by the multimedia content. However, there exists the security question in the above-mentioned three categories of the authentication schemes. In this paper, a novel concept that is called "authentication set" is used to analyze the security of the authentication schemes in detail. Several novel concepts on the authentication set are defined, which are called "Cover Authentication Set", "Attack Authentication Set", "Watermark-based Authentication Set" or "Signature-based Authentication Set", "Verified Authentication Set" and "Malicious-attack Authentication Set". According to the relation among the aforementioned sets, the security of the authentication schemes is exploited. Furthermore, a conclusion is drawn according to the analysis result. At the same time the principle that guides the design of the more secure authentication schemes is presented. Finally, as an example, a novel authentication design method based on multi-feature watermarks is proposed according to the design principle. The experimental results prove the validity of the design method and the significance of the guide principle.

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DOI: 10.3217/jucs-014-19-3174

Authors: Manuel Veit, Antonio Capobianco, Dominique Bechmann

Abstract: We developed a free form deformation application for an immersive environment in which users can interact freely using data gloves. To ensure better comfort and performances, we added the possibility of bi-manual interaction in our environment. To investigate the actual gain obtained by this interaction technique we designed an experimental protocol based on spatial input tasks. In our experiment, we asked our subjects to use only the dominant hand to achieve the different tasks or, on the contrary, to use both hands. Comparison of users' performances - i-e, time and precision - shows that, without proper training, executing a task using two hands can be more time consuming than using one hand. In fact, the degree of symmetry of the tasks performed with each hand seem to have a significant impact on whether or not users take advantage of bi-manual possibilities. Our results also show that bi-manual interaction can introduce proprioceptive cues that can be of help to achieve more precision in the placement or selection only when proper visual information are missing. In this study, we also wanted to investigate if bi-manual interaction can help users in their perception of the task. Even if there aren't statistically significant, our results shows that using symmetric bi-manual interaction, proprioception cues can improve user's perception.

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DOI: 10.3217/jucs-014-19-3114

Authors: Jesús Ibáñez, David García, Oscar Serrano

Abstract: This paper presents Musimage, a novel system which displays pictures according to the songs being played at the same time. By using the interface the user selects the songs to be played, but the pictures are automatically selected. For each song to be played, the system selects a set of pictures, according to various criteria corresponding to some features of the song. In this sense, the pictures to be shown are, metaphorically, triggered by the songs.

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DOI: 10.3217/jucs-014-17-2840

Authors: Roberto Arroyo, Miguel Gea, José Garrido, Pablo Haya, Rosa Carro

Abstract: Social-aware computing is an emerging trend based on ubiquitous computing technologies and collaborative work. A successful design demands a better understanding of group tasks, adaptation mechanisms and support for dynamic changes in a nomadic computing paradigm. This paper proposes the use of a hypermedia model to describe and support group activities in intelligent environments. The resulting system integrates adaptive context-aware information on the basis of user/group models in order to provide a structured access to dynamic task scheduling. In particular, we propose the use of the calendar metaphor as an ongoing connection between active spaces and collaborative tasks. This proposal provides the appropriate support for an easier human coordination to achieve common objectives in blended learning scenarios, and thus, extending authoring social tasks to physical spaces.

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DOI: 10.3217/jucs-014-10-1792

Authors: Marc Spaniol, Ralf Klamma, Mathias Lux

Abstract: With the advent of Web 2.0 technologies a new attitude towards processing contents in the Internet has emerged. Nowadays it is a lot easier to create, share and retrieve multimedia contents on the Web. However, with the increasing amount in contents retrieval becomes more challenging and often leads to inadequate search results. One main reason is that image clustering and retrieval approaches usually stick either solely to the images' low-level features or their user-generated tags (high-level features). However, this is frequently inappropriate since the "real" semantics of an image can only be derived from the combination of low-level and high-level features. Consequently, we investigated a more holistic view on image semantics based on a system called Imagesemantics. This system combines MPEG-7 descriptions for low-level content-based retrieval features and MPEG-7 keywords by a machine learning approach producing joined OWL rules. The rule base is used in Imagesemantics to improve retrieval results.

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DOI: 10.3217/jucs-014-10-1775

Authors: Tobias Bürger

Abstract: The digital media and games industry is one of the biggest IT based indus-tries worldwide. Recent observations therein showed that current production workflows may be potentially improved as multimedia objects are mostly created from scratch due to insu±cient reusability capacities of existing tools. In this paper we provide reasons for that, provide a potential solution based on semantic technologies, show the potential of ontologies, and provide scenarios for the application of semantic technologies in the digital media and games industry.

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DOI: 10.3217/jucs-014-10-1695

Authors: Muhammad Khan, Narayanan Kulathuramaiyer, Hermann Maurer

Abstract: The WWW is currently experiencing a revolutionary growth due to numerous emerging tools, techniques and concepts. Digital journals thus need to transform themselves to cope with this evolution of the web. With their growing information size and access, conventional techniques for managing a journal and supporting authors and readers are becoming insufficient. Journals of the future need to provide innovative administrative tools in helping its managers to ensure quality. They also need to provide better facilities for assisting authors and readers in making decisions regarding their submission of papers and in providing novel navigational features for finding relevant publications and collaborators in particular areas of interest. In this paper, we explore an innovative solution to address these problems by using an emerging Web 2.0 technology. We explore the application of mash-ups for J.UCS - the Journal of Universal Computer Science and encourage readers and authors to try out the applications (see section 11 Conclusions). J.UCS can then serve as a model for contemporary electronic journals.

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DOI: 10.3217/jucs-014-10-1625

Authors: Guru Hacker Test

Abstract: Communication processes have become increasingly important in modern working life. Organizations invest a surprisingly high amount of financial resources and employee work time in both face-to-face and virtual meetings, yet this investment often produces poor results. To overcome this problem, research on technology-based support over a meeting’s life-cycle has been increasingly conducted in recent decades. As a result of this research, particular interest has emerged in meeting information systems, which may include technology-enhanced meeting rooms as well as tools for multi-modal meeting recording, automatic meeting information extraction and annotation, in-meeting support, meeting information archiving, indexing, retrieval and visualization. Despite this great interest in and research activity on meeting information systems, insufficient focus has been paid into flexible architectures, interchangeability of meeting information as well as the integration into business processes and applications. This situation has motivated our research consortium to direct the research activity within the MISTRAL project towards a flexible and extendable system that can be easily integrated into daily working environments for knowledge access and learning activities. In this paper, we give an overview about electronic meeting systems, introduce related work on meeting information systems, outline the MISTRAL concept and its implementation, and based on that we discuss findings and problems with our research.

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DOI: 10.3217/jucs-014-09-1513

Authors: María González, Toni Granollers, Afra Pascual

Abstract: Although usability evaluations have been focused on assessing different contexts of use, no proper specifications have been addressed towards the particular environment of academic websites in the Spanish-speaking context of use. Considering that this context involves hundreds of millions of potential users, the AIPO Association is running the UsabAIPO Project. The ultimate goal is to promote an adequate translation of international standards, methods and ideal values related to usability in order to adapt them to diverse Spanish-related contexts of use. This article presents the main statistical results coming from the Second and Third Stages of the UsabAIPO Project, where the UsabAIPO Heuristic method (based on Heuristic Evaluation techniques) and seven Cognitive Walkthroughs were performed over 69 university websites. The planning and execution of the UsabAIPO Heuristic method and the Cognitive Walkthroughs, the definition of two usability metrics, as well as the outline of the UsabAIPO Heuristic Management System prototype are also sketched.

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DOI: 10.3217/jucs-014-04-0590

Authors: Maytham Safar

Abstract: Over the last decade, due to the rapid developments in information technology (IT), a new breed of information systems has appeared such as geographic information systems that introduced new challenges for researchers, developers and users. One of its applications is the car navigation system, which allows drivers to receive navigation instructions without taking their eyes off the road. Using a Global Positioning System (GPS) in the car navigation system enables the driver to perform a wide range of queries, from locating the car position, to finding a route from a source to a destination, or dynamically selecting the best route in real time. Several types of spatial queries (e.g., nearest neighbour - NN, K nearest neighbours - KNN, continuous k nearest neighbours - CKNN, reverse nearest neighbour - RNN) have been proposed and studied in the context of spatial databases. With spatial network databases (SNDB), objects are restricted to move on pre-defined paths (e.g., roads) that are specified by an underlying network. In our previous work, we proposed a novel approach, termed Progressive Incremental Network Expansion (PINE), to efficiently support NN and KNN queries. In this work, we utilize our developed PINE system to efficiently support other spatial queries such as CKNN. The continuous K nearest neighbour (CKNN) query is an important type of query that finds continuously the K nearest objects to a query point on a given path. We focus on moving queries issued on stationary objects in Spatial Network Database (SNDB) (e.g., continuously report the five nearest gas stations while I am driving.) The result of this type of query is a set of intervals (defined by split points) and their corresponding KNNs. This means that the KNN of an object travelling on one interval of the path remains the same all through that interval, until it reaches a split point where its KNNs change. Existing methods for CKNN are based on Euclidean distances. In this paper we propose a new algorithm for answering CKNN in SNDB where the important measure for the shortest path is network distances rather than Euclidean distances. Our solution addresses a new type of query that is plausible to many applications where the answer to the query not only depends on the distances of the nearest neighbours, but also on the user or application need. By distinguishing between two types of split points, we reduce the number of computations to retrieve the continuous KNN of a moving object. We compared our algorithm with CKNN based on VN3 using IE (Intersection Examination). Our experiments show that our approach has better response time than approaches that are based on IE, and requires fewer shortest distance computations and KNN queries.

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DOI: 10.3217/jucs-014-04-0557

Authors: Astrid Dickinger, Steffen Zorn

Abstract: Due to a shift in the marketing focus from mass to micro markets, the importance of one-to-one communication in advertising has increased. Interactive media provide possible answers to this shift. However, missing standards in payment models for interactive media are a hurdle in the further development. The paper reviews interactive advertising payment models. Furthermore, it adapts the popular FCB grid as a tool for both advertisers and publishers or broadcasters to examine effective interactive payment models.

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DOI: 10.3217/jucs-014-04-0546

Authors: Christian Safran, Frank Kappe

Abstract: User generated content published via weblogs (also known as blogs) has gained importance in the last years, and the number of globally available weblogs increases. However, a large fraction of these show low publishing activity and are rarely read. This paper is a quantitative analysis of success factors in a community of over 15.000 weblogs, hosted by a local Austrian newspaper. We looked at publishing activity by content type, community activity and writing style. Also, the interconnectedness of the community was analyzed.

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DOI: 10.3217/jucs-014-01-0059

Authors: Stephan Lukosch

Abstract: Nowadays, more and more users make use of web-based collaborative systems. Users participate in communities or search for and provide information in webbased systems. They access shared resources which they need for their professional life or for learning. One of the major prerequisites of such web-based systems is that users have to be connected to the network. But life has become much more mobile over the last years. While traveling, e.g. to the office or the university, users often are disconnected from the network. This makes it difficult to interact with other users or to access shared resources. An application supporting a seamless transition between connected and disconnected phases would allow users to work at any time and place while maintaining the advantages of a web-based collaborative system once they are online again. In this article, we describe the requirements that a web-based collaborative system has to fulfill to enable a nomadic use. We show how we extended the web-based collaborative system CURE to fulfill these requirements and how our approach can be transferred to other web-based collaborative systems.

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DOI: 10.3217/jucs-013-09-1157

Authors: Sinuhé Arroyo

Abstract: Ontologies have been recognized as a fundamental infrastructure for advanced approaches to Knowledge Management (KM) automation in SOA. Building services communicate with each other by exchanging self-contained messages. Depending on the specific requirements of the business model they serve and the application domain for which services were deployed, a number of mismatches (i.e. sequence and cardinality of messages exchanges, structure and format of messages and content semantics), can occur which prevent interoperation among a prior compatible services. Existing choreography technologies attempt to model such external visible behavior. However, they lack the consistent semantic support required to fully meet the necessities of heterogeneous KM environments. This paper describes the ontology and grammar of SOPHIE, a semantic service-based choreography framework for overcoming conversational pattern mismatches in knowledge intensive environments. Consequently, the paper provides an overview of the framework that depicts its main building blocks, so a good understantind of the ontology and grammar that summarize the conceptual model is gained. Such ontology allows the desing and description of fully fledged choreographies that can be used, as a result of a mediation task, to produce the mediating structures that in fact allow dynamic service-to-service interoperation. Finally, a use case centred in the telcomunications field serves as proof of concept of how SOPHIE is being applied.

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DOI: 10.3217/jucs-013-04-0543

Authors: Dimitrios Tsolis, Spyros Sioutas, Lambros Drossos, Theodore Papatheodorou

Abstract: The issue addressed in this paper focuses on the design and implementation of an advanced information system for Cultural Organizations, which serves as a platform for the exploitation through e-Commerce web services and, in parallel, the protection of copyright and digital rights management of the cultural content. The main components of the information system are: (a) Digital Image Library, which offers specialized services, (b) copyright protection and digital rights management of digitized material and (c) the E-Commerce web services, supported by advanced technologies, for the proper exploitation of the digital cultural content. The work described in this contribution focuses on digitized material of Cultural Heritage and is deployed at several cultural organizations.

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DOI: 10.3217/jucs-013-04-0531

Authors: Narayanan Kulathuramaiyer

Abstract: The WWW is currently experiencing a revolutionary growth due to its increasing participative community software applications. This paper highlights an emerging application development paradigm on the WWW, called mashup. As blogs have enabled anyone to become a publisher, mashups stimulate web development by allowing anyone to combine existing data to develop web applications. Current applications of mashups include tracking of events such as crime, hurricanes, earthquakes, meta-search integration of data and media feeds, interactive games, and as an organizer for web resources. The implications of this emerging web integration and structuring paradigm remains yet to be explored fully. This paper describes mashups from a number of angles, highlighting current developments while providing sufficient illustrations to indicate its potential implications. It also highlights the role of mashups in complementing and enhancing digital journals by providing insights into the quality academic content, extent of coverage, and the enabling of expanded services. We present pioneering initiatives for the Journal of Universal Computer Science in our efforts to harness the collective intelligence of a collaborative scholarly network.

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DOI: 10.3217/jucs-013-02-0177

Authors: Ken Saito, Hidekazu Kubota, Yasuyuki Sumi, Toyoaki Nishida

Abstract: In this paper, we present a computational approach to understanding and augmenting the conversational knowledge process. We introduce the concept of the conversation quantization, a technique of approximating a continuous flow of conversation by a series of conversation quanta that represent points of the discourse. To investigate what the nature of conversation quanta is, we attempt to extract conversation quanta from two types of the meeting videos by hand. As a result, we have obtained some profitable suggestions about conversation quanta.

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DOI: 10.3217/jucs-013-02-0161

Authors: Daisaku Arita, Rin-Ichiro Taniguchi

Abstract: We propose a concept of real-time human proxy for avatar-based communication systems, which virtualizes a human in the real world in real-time and which lets the virtualized human behave as if he/she was present at a distant place. For estimating RHP, we apply it to a simple game and a virtual classroom system. The experimental results shows us that RHP is useful for avatar-based communication.

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DOI: 10.3217/jucs-013-02-0135

Authors: Hidekazu Kubota, Satoshi Nomura, Yasuyuki Sumi, Toyoaki Nishida

Abstract: We present a concept and implementation of a computational support for spatial memory management and describe its temporal evolution. Our essential idea is to use an immersible globe that consists of a global space and a conical space, thereby providing arbitrary memory space for humans. We developed a sustainable knowledge globe (SKG) for constructing a memory space, and proposed a system called Contents Garden to expand the SKG into immersive space. We carried out the user study of SKG to evaluate its effectiveness. We also proposed and discussed three perceptual operations on Contents Garden to improve the operativity of the SKG.

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DOI: 10.3217/jucs-012-03-0284

Authors: Pablo Haya, Germán Montoro, Abraham Esquivel, Manuel García-Herranz, Xavier Alamán

Abstract: Ambient Intelligence scenarios describe situations in which multitude of devices and agents live together. In this kind of scenarios is frequent to see the appearance of conflicts when modifying the state of a device as for example a lamp. Those problems are not as much of sharing of resources as of conflict of orders coming from different agents. This coexistence must deal also with the desire of privacy of the different users over their personal information such as where they are, what their preferences are or to whom this information should be available. When facing incompatible orders over the state of a device it turns necessary to make a decision. In this paper we propose a centralised mechanism based on prioritized FIFO queues to decide the order in which the control of a device is granted. The priority of the commands is calculated following a policy that considers issues such as the commander's role, command's type, context's state and commander-context and commander-resource relations. Finally we propose a set of particular policies for those resources that do not adjust to the general policy. In addition we present a model pretending to integrate privacy through limiting and protecting contextual information.

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DOI: 10.3217/jucs-012-02-0187

Authors: Josef Kolbitsch, Hermann Maurer

Abstract: To date, one of the main aims of the World Wide Web has been to provide users with information. In addition to private homepages, large professional information providers, including news services, companies, and other organisations have set up web-sites. With the development and advance of recent technologies such as wikis, blogs, podcasting and file sharing this model is challenged and community-driven services are gaining influence rapidly. These new paradigms obliterate the clear distinction between information providers and consumers. The lines between producers and consumers are blurred even more by services such as Wikipedia, where every reader can become an author, instantly. This paper presents an overview of a broad selection of current technologies and services: blogs, wikis including Wikipedia and Wikinews, social networks such as Friendster and Orkut as well as related social services like del.icio.us, file sharing tools such as Flickr, and podcasting. These services enable user participation on the Web and manage to recruit a large number of users as authors of new content. It is argued that the transformations the Web is subject to are not driven by new technologies but by a fundamental mind shift that encourages individuals to take part in developing new structures and content. The evolving services and technologies encourage ordinary users to make their knowledge explicit and help a collective intelligence to develop.

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DOI: 10.3217/jucs-012-01-0099

Authors: Zhenjiang Miao, Baozong Yuan, Mengsun Yu

Abstract: This paper proposes a Human-centered Pervasive Computing System Model (HPC), a Layered Architectural Analysis and Design Method (LAAD) and a Waterfall Prototyping Process Model (WPP). Based on the HPC model and the LAAD method, a pervasive computing based multimodal tele-home healthcare system is designed and partly implemented using the Waterfall Prototyping Process. The design and implementation issues are discussed in more detail. Some testing results are presented.

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DOI: 10.3217/jucs-011-11-1792

Authors: Klaus Hinum, Silvia Miksch, Wolfgang Aigner, Susanne Ohmann, Christian Popow, Margit Pohl, Markus Rester

Abstract: Tracking and comparing psychotherapeutic data derived from questionnaires involves a number of highly structured, time-oriented parameters. Descriptive and other statistical methods are only suited for partial analysis. Therefore, we created a novel spring-based interactive Information Visualization method for analysing these data more in-depth. With our method the user is able to find new predictors for a positive or negative course of the therapy due to the combination of various visualization and interaction methods.

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DOI: 10.3217/jucs-011-11-1752

Authors: Martin Atzmueller, Frank Puppe

Abstract: Visual mining methods enable the direct integration of the user to overcome major problems of automatic data mining methods, e.g., the presentation of uninteresting results, lack of acceptance of the discovered findings, or limited confidence in these. We present a novel subgroup mining approach for explorative and descriptive data mining implemented in the VIKAMINE system. We propose several integrated visualization methods to support subgroup mining. Furthermore, we describe three case studies using data from fielded systems in the medical domain.

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DOI: 10.3217/jucs-011-09-1555

Authors: Miguel A. Vega-Rodríguez, Juan Gómez-Pulido, Juan Sánchez-Pérez

Abstract: ICT (Information and Communication Technologies) are a very important educational resource at the present time because they allow place and time limitations to be overcome and therefore reduce costs. In addition, multimedia applications offer a set of characteristics in order to improve learning by means of interactive activities. For these reasons, we believe it is important to devote efforts to the development of proposals and prototypes for teaching via Internet. Since 1998, our research group has been focused on this objective and working on diverse projects such as SD2I, TEDA or PDIWeb. In this paper we overview all these projects, presenting a general description of each web platform, as well as the tools and methods used for their implementation. This paper also includes the results obtained after the use of each platform and the feedback from surveys. In this way, several conclusions are presented in the last section of this paper.

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DOI: 10.3217/jucs-011-09-1470

Authors: Pilar Sancho, Iván Martínez, Baltasar Fernández-Manjón

Abstract: Despite the increasing importance gained by e-learning standards in the past few years, and the unquestionable goals reached (mainly regarding interoperability among e-learning contents) current e-learning standards are yet not sufficiently aware of the context of the learner. This means that only a limited support for adaptation regarding individual characteristics is currently being provided. In this article, we propose the use of semantic metadata for Learning Object (LO) contextualization in order to adapt instruction to the learner's cognitive requirements in three different ways: background knowledge, knowledge objectives and the most suitable learning style. In our pilot e-learning platform () the context for LOs is addressed in two different ways: knowledge domain and instructional design. We propose the use of ontologies as the knowledge representation mechanism to allow the delivery of learning material that is relevant to the current situation of the learner.

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DOI: 10.3217/jucs-011-06-0944

Authors: Vladimir Kutálek, Václav Dvořák

Abstract: A recent renewed interest in hypercube interconnection network has been concentrated to the more scalable version known as a fat cube. The paper introduces several router models for fat nodes and uses them for cost comparison of both the hypercube and fat cube topologies. Analysis of time complexity of collective communications is done next and lower bounds on the number of communication steps are derived. Examples of particular communication algorithms on the 2D-fat cube topology with 8 processors are summarized and described in detail. The performed study shows that a large variety of fat cubes can provide much desired flexibility, trading cost for performance and manufacturability.

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DOI: 10.3217/jucs-011-03-0378

Authors: Stefan Münzer, Bo Xiao

Abstract: E-learning at the workplace might be accomplished by synchronous cooperative learning sessions of small groups using net-based communication. This form of learning is suitable both for course-based e-learning as well as for knowledge transfer within the company. The small groups learn self-regulated, i.e. without the guidance of an instructor. However, the learning tasks are pre-defined and a specific learning process is precisely described. In the present study, the goal of the cooperative learning sessions is to deepen pre-existing declarative knowledge. During cooperative learning, group members are required to actively use, acquire, enrich and exchange their knowledge. In a field study carried out in a large software company, a software tool was used which supported the specific process by phase-specific delivering of instructions and learning materials as well as by means of process control (including turn-taking, role assignment, and coordination of task flow). The results of the empirical evaluation demonstrate a high amount of topic-oriented contributions and the realization of the expected learning activities. However, feedback data indicated a low acceptance of the software tool because of its restrictive process control. It is discussed that there might have been a non-optimal interaction between the factors technology and target group in the study.

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DOI: 10.3217/jucs-011-01-0122

Authors: Ravi Veerubhotla, Ashutosh Saxena, V. Gulati, A. Pujari

Abstract: This work presents two new construction techniques for q-ary Gossip codes from t-designs and Traceability schemes. These Gossip codes achieve the shortest code length specified in terms of code parameters and can withstand erasures in digital fingerprinting applications. This work presents the construction of embedded Gossip codes for extending an existing Gossip code into a bigger code. It discusses the construction of concatenated codes and realisation of erasure model through concatenated codes.

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DOI: 10.3217/jucs-011-01-0066

Authors: Nadia Nedjah, Luiza Mourelle

Abstract: Most cryptography systems are based on the modular exponentiation to perform the non-linear scrambling operation of data. It is performed using successive modular multiplications, which are time consuming for large operands. Accelerating cryptography needs optimising the time consumed by a single modular multiplication and/or reducing the total number of modular multiplications performed. Using a genetic algorithm, we first yield the minimal sequence of powers, generally called addition chain, that need to be computed to finally obtain the modular exponentiation result. Then, we exploit the co-design methodology to engineer a cryptographic device that accelerates the encryption/decryption throughput without requiring considerable hardware area. Moreover the obtained designed cryptographic hardware is completely secure against known attacks.

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DOI: 10.3217/jucs-011-01-0056

Authors: Nedeljko Cvejic, Tapio Seppänen

Abstract: In this paper, we present a novel high bit rate LSB audio watermark ing method that reduces embedding distortion of the host audio. Using the proposed twostep algorithm, watermark bits are embedded into higher LSB layers, resulting in increased robustness against noise addition. In addition, listening tests showed that perceptual quality of watermarked audio is higher in the case of the proposed method than in the standard LSB method.

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DOI: 10.3217/jucs-010-03-0235

Authors: Jasminko Novak, Michael Wurst

Abstract: This paper discusses some implications of knowledge creation processes in informal social networks for the development of technologies to support them. The principal point of departure are social theories of learning and the theories of organisational knowledge creation. The focus is on models for the exchange and sharing of implicit knowledge. A model of personalised learning knowledge maps is presented as one possible way of addressing the problem of capturing, visualising and sharing implicit knowledge of a community of users. In particular, we discuss how this model resolves one critical shortcoming of the existing socialisation and externalisation approaches: the creation of a semantic representation of a shared understanding of the community which reflects implicit knowledge and incorporates personal views of individual users. Finally, we outline the application to a real-world interdisciplinary Internet platform netzspannung.org.

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