DOI: 10.3897/jucs.178088

Authors: Juana María Morcillo Martínez, José L. López Ruiz, David Díaz-Jiménez, María Mercedes Párraga Vico, Macarena Espinilla Estévez

Abstract: he objective of this study is to analyze the acceptance and ethical conditions required for the implementation of non-invasive monitoring systems for older adults. Using a mixed-methods design, it integrates focus groups with older adults and a questionnaire with future social and healthcare professionals. The results show a high level of acceptance of wearable technologies that do not use cameras or microphones, highlighting their discreet nature, protection of privacy, and contribution to autonomy and safety. Participants valued person-centered design, transparency in data use, and technologies that complement—rather than replace—human support. The main perceived barriers were cost, lack of training, and the digital divide. These findings indicate that wearable devices can support aging in place when developed through participatory and ethical approaches that respect dignity and promote trust. The study concludes that successful implementation requires user involvement, clear communication, and sustainable strategies for integration into social and healthcare services.

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DOI: 10.3897/jucs.162705

Authors: Guadalupe Ortiz, Javier Tena, Adrian Garcia-Bermejo, Alfonso Garcia-de-Prado, Stephan Reiff-Marganiec

Abstract: The Internet of Things (IoT) has experienced rapid growth, taking advantage of advanced data processing. While complex event processing (CEP) engines have positioned themselves as a good solution for cloud and fog data processing, there are no CEP solutions designed to run on microcontrollers (MCUs) at the edge. This paper presents MicroCEP, a software architecture for MCUs that enables real-time filtering and correlation of sensor data, both locally obtained and received through message queues at the edge. MicroCEP provides (i) a lightweight CEP architecture for MCUs, (ii) a pattern language to specify complex event patterns, (iii) a REST API for dynamic threshold updates, and (iv) a methodology for designing and deploying MicroCEP-based systems. The solution facilitates the detection of situations of interest and the triggering of actions directly from the MCUs, enabling autonomous decision-making close to the sensors. A proof of concept implementation using RISC-V MCUs provides evidence that MicroCEP can deliver CEP capabilities at the edge on resource.constrained devices.

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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.71645

Authors: Roberto Cavicchioli, Riccardo Martoglia, Micaela Verucchi

Abstract: Exposing city information to dynamic, distributed, powerful, scalable, and user-friendly big data systems is expected to enable the implementation of a wide range of new opportunities; however, the size, heterogeneity and geographical dispersion of data often makes it difficult to combine, analyze and consume them in a single system. In the context of the H2020 CLASS project, we describe an innovative framework aiming to facilitate the design of advanced big-data analytics workflows. The proposal covers the whole compute continuum, from edge to cloud, and relies on a well-organized distributed infrastructure exploiting: a) edge solutions with advanced computer vision technologies enabling the real-time generation of “rich” data from a vast array of sensor types; b) cloud data management techniques offering efficient storage, real-time querying and updating of the high-frequency incoming data at different granularity levels. We specifically focus on obstacle detection and tracking for edge processing, and consider a traffic density monitoring application, with hierarchical data aggregation features for cloud processing; the discussed techniques will constitute the groundwork enabling many further services. The tests are performed on the real use-case of the Modena Automotive Smart Area (MASA).

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DOI: 10.3897/jucs.77247

Authors: Christopher Cichiwskyj, Gregor Schiele

Abstract: When the complexity of a problem rises, its solution requires more hardware resources. A usual way to solve this is to use larger processors and add more memory. When using Field Programmable Gate-Arrays (FPGAs), which can instantiate arbitrary circuit designs, a larger, more costly and power hungry chip is used. In this paper we propose a different approach, namely to split the problem into a graph of interdependent smaller tasks and to reconfigure a small FPGA during runtime to execute each of these tasks efficiently sequentially. This can result in cheaper and more energy efficient systems that can execute very complex problems locally. We present a basic analytical model, evaluate its accuracy and discuss initial insight from it.

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DOI: 10.3897/jucs.71831

Authors: Nermin Kajtazovic, Peter Hödl, Leo Happ Botler

Abstract: Coexistence of software components and functions of different criticality in a single computing platform has challenged the safety community for the past two decades. Despite efforts that have been made so far, dealing with mixed-criticality has still left some room for improvements. One particular concern here is that partitioning of hardware and software resources with regard to criticality (safety related, non-safety related) has direct implications on how safety measures need to be realised. For example, a self-test that must meet certain diagnostic coverage for the microcontroller core by inspecting its instructions, needs to cover only those instructions which are able to affect a safety function. Available software mechanisms and tools are to a certain extent still unable to deal with such a fine-grained selection of resources. In this work, we introduce a compiler extension and language support which enable accurate selection of data based on their criticality. The compiler extension serves to establish detailed traceability between the software code and its representation in runtime memory. With the language support, the individual data elements can be classified based on the desired safety integrity level. As a result, safety measures that operate on data (e.g. Abraham test for SRAM can achieve better coverage. The method has been evaluated and applied to industrial safety controllers. We provide here relevant performance figures and discuss possible applications of the method in other fields.

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DOI: 10.3897/jucs.70325

Authors: Manel Mena, Javier Criado, Luis Iribarne, Antonio Corral

Abstract: Cyber-Physical Systems (CPS) and Internet of Things (IoT) devices are handled by numerous different protocols. The management and connection to those devices tend to create usability and integrability issues. This brings about the need for a solution capable of facilitating the communication between different platforms and devices. The Web of Things (WoT) describes interfaces and interaction patterns among things, thereby abstracting itself from the underlying protocols used to manage those things and their implementation strategies. This paper describes the concept of Digital Dice, an abstraction of IoT devices and CPS capable of leveraging the advantages of microservices architectures and inspired by the concept of Digital Twins. A Digital Dice is a servient system of the WoT domain that represents a device by the features of the device, hence different WoT description models result in different microservices related to the particular thing. The paper explores the definition of Digital Dices and the conversion between WoT Thing Description Models and Digital Dices and the architecture that sustains the system.

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DOI: 10.3897/jucs.2020.077

Authors: Lelio Campanile, Mauro Iacono, Fiammetta Marulli, Michele Mastroianni, Nicola Mazzocca

Abstract: Technological development and market expansion offer an increased availability of resources and computing power on IoT nodes at affordable cost. The edge computing paradigm allows keeping locally on the edge of the network a part of computing, while keeping all advantages of the cloud and adding support for privacy, real-time and network resilience. This can be further improved in IoT applications by exibly harvesting resources on IoT nodes, by moving part of the computing tasks related to data from the edge server to the nodes, raising the abstraction level of the data aspects of the architecture and potentially enabling larger IoT networks to be efficiently deployed and managed, in a stand-alone logic or as a component of edge architecture. Anyway, an e_cient energy management mechanism is needed for battery powered IoT networks, the most exible implementations, that dynamically balances task allocation and execution in order to In this paper we present a fuzzy logic based power management strategy for IoT subsystem that aims at maximizing the duration of the network by locally migrating part of the computing tasks between nodes. As our goal is to enable the deployment of semi-autonomic large IoT networks, our proposal does not rely on external resources for migration control and operates on a local basis to ensure scalability: at the best of our knowledge, this differentiates our proposal with respect to similar solutions available in literature.

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DOI: 10.3217/jucs-025-08-0925

Authors: Ashot Harutyunyan, Arnak Poghosyan, Naira Grigoryan, Narek Hovhannisyan, Nicholas Kushmerick

Abstract: We address several problems in intelligent log management of distributed cloud computing applications and their machine learning solutions. Those problems concern various tasks on characterizing data center states from logs, as well as from related or other quantitative metrics (time series), such as anomaly and change detection, identification of baseline models, impact quantification of abnormalities, and classification of incidents. These are highly required jobs to be performed by today's enterprise-grade cloud management solutions. We describe several approaches and algorithms that are validated to be effective in an automated log analytics combined with analytics from time series perspectives. The paper introduces novel concepts, approaches, and algorithms for feasible log-plus-metric-based management of data center applications in the context of integration of relevant technology products in the market.

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DOI: 10.3217/jucs-022-05-0671

Authors: Yolanda Baca-Gomez, Alicia Martinez, Paolo Rosso, Hugo Estrada, Delia Irazu Hernandez Farias

Abstract: The increasing use of social networks and online sites where people can express their opinions has created a growing interest in Opinion Mining. One of the main tasks of Opinion Mining is to determine whether an opinion is positive or negative. Therefore, the role of the feelings expressed on the web has become crucial, mainly due to the concern of businesses and government to automatically identify the semantic orientation of the views of customers or citizens. This is also a concern, in the area of health to identify psychological disorders. This research focuses on the development of a web application called SWePT (Web Service for Polarity detection in Spanish Texts), which implements the Sequential Minimal Optimization (SMO) algorithm, extracting its features from an affective lexicon in Mexican Spanish. For this purpose, a corpus and an affective lexicon in Mexican Spanish were created. The experiments using three (positive, neutral, negative) and five categories (very positive, positive, neutral, negative, and very negative) allow us to demonstrate the effectiveness of the presented method. SWePT has also been implemented in the Emotion-bracelet interface, which shows the opinion of a user graphically.

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DOI: 10.3217/jucs-021-02-0177

Authors: Jose Gutiérrez-Rivas, Simon Holmbacka, Miguel Míndez-Macías, Wictor Lund, Sebastien Lafond, Johan Lilius, Javier Díaz-Alonso

Abstract: Safety-critical systems and certification standards are the bare essential elements for the development process of avionics, automotive and industrial embedded systems. The necessity of including non-safety capabilities to reduce the price of these systems has resulted in a new type of critical systems, the mixed-criticality ones. These systems should be able to execute safety-critical applications but, at the same time, to run non-safety-critical functionalities without affecting the integrity of the safety-critical tasks. This paper presents a new system architecture which includes safety-critical and non-safety-critical parts in order to form a mixed-criticality system. The system consists of a reliable platform with a dual-core processor (implemented using a FPGA) architecture designed as open-hardware, running two isolated real-time operating systems which are connected through a safe core-to-core communication channel that executes the safety-critical applications. Moreover, the safety-critical system is connected to an external processor, an ARM9, which is used as an external sensing system. The ARM9 runs the non-safety-critical applications and allows the system to insert modifications updating without affecting the safety capabilities of the safety-critical part. This platform is described providing evidences of the isolation between safety-critical (SC) and non-safety-critical (NSC) applications, as well as describing an updating methodology for non-safety-critical applications. This system is validated using a complete and reliable application for safe emergency stop applications for industrial machinery.

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DOI: 10.3217/jucs-020-08-1109

Authors: Dulce Domingos, Francisco Martins, Carlos Cândido, Ricardo Martinho

Abstract: Business processes can use Internet of Things (IoT) information to monitor context data in real-time and to respond to changes in their values in a timely fashion. For this matter, business process definition and execution languages should foresee an easy way for process modelers to define which values to monitor, and which automatic behaviors to adopt when these values change. In this paper, we propose the use of context variables to monitor sensor values, as well as a when-then language construct to detect and handle changes in these values within business processes. We define a Web Services Business Process Execution Language (WS-BPEL) extension to convey these constructs, and implement then using a "BPEL language transformation" approach. With these contributions, process modelers can define IoT-aware business processes avoiding the increase of process complexity and keeping their focus on modeling the processes' main logic. In addition, the language transformation approach assures the portability of processes using our constructs amongst WS-BPEL execution engines.

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DOI: 10.3217/jucs-019-15-2292

Authors: Javier Fernández, Juan Augusto, Giuseppe Trombino, Ralf Seepold, Natividad Madrid

Abstract: Traders are required to work in the financial market with highly complex information and to perform efficiently under high levels of psychological pressure. Multiple disciplines, from programs with artificial intelligence to complex mathematical functions, are used to help traders in their effort to maximize profits. However, an essential problem not yet considered in this rapidly evolving environment is that traders are not supported to adequately manage how stress influences their decisions. This paper takes into consideration the negative influences of stress on individuals and proposes a system designed to support traders by providing them with information that can reduce the likelihood of poor decision-making. The system has been designed considering both technical and physiological aspects to make information available in a suitable way. Biometric sensors are used to collect data associated with stress, a software platform then analyses this information and displays it to the trader. The resulting system is capable of making individual traders, as well as teams of traders, self-aware of their levels of stress. The system has been tested in real environments and the results provide evidence that self-aware traders benefit from the system by reducing risky decision-making.

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DOI: 10.3217/jucs-019-09-1219

Authors: Antonio Jara, David Fernandez, Pablo Lopez, Miguel Zamora, Antonio Skarmeta, Leandro Marin

Abstract: Bluetooth Low Energy (BLE) is extending Bluetooth technology to devices with lower communication requirements and higher constraints in terms of memory capabilities and power autonomy. Thereby, BLE makes feasible the wireless transmission of information from smart objects such as wearable clinical devices, ambient sensors and actuators. These smart objects are starting to be internet-enabled devices, reaching the so denominated Internet of Things (IoT). Our research work is focused on analyze the capabilities of these technologies for continuous data transmission and integration of clinical sensors in home-care and Ambient Assisted Living environments. For this purpose, this work analyses exhaustively the capabilities from BLE and compare this with the capabilities from Bluetooth 2.1. In addition, it has been considered the communications requirements from different clinical devices such as an electrocardiogram (ECG) and a capnograph. It is concluded that the performance from BLE is lower than Bluetooth Classic (Bluetooth 2.1) for continuous communications, since BLE is based on attributes (datapoints) transfer instead of offering a communication session where can be transmitted as much packets as required, without any size constraint. Therefore, it is necessary to perform data compression/aggregation when the amount of data to send is too large to be stored in a BLE attribute. This work also presents how to apply pre-processing techniques that greatly reduces the transmission overload (performs signal compression) in order to allow the continuous transmission of the ECG and capnograph signal through BLE making so feasible the integration of continuous clinical devices via BLE.

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DOI: 10.3217/jucs-019-03-0282

Authors: Matija Cankar, Matej Artač, Marjan Šterk, Uroš Lotrič, Boštjan Slivnik

Abstract: We present a new algorithm for resource allocation in large, heterogeneous grids. Its main advantage over existing co-allocation algorithms is that it supports collective requests with partial resource reservation, where the focus is on better grid utilisation. Alongside the requests that must be fulfilled by each resource, a collective request specifies the total amount of a required resource property without a strict assumption with regard to its distribution. As a consequence, the job becomes much more flexible in terms of its resource assignment and the co-allocation algorithm may therefore start the job earlier. This flexibility increases grid utilisation as it allows an optimisation of job placement that leads to a greater number of accepted jobs. The proposed algorithm is implemented as a module in the XtreemOS grid operating system. Its performance and complexity have been assessed through experiments on the Grid'5000 infrastructure. The results reveal that in most cases the algorithm returns optimal start times for jobs and acceptable, but sometimes suboptimal resource sets.

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DOI: 10.3217/jucs-018-11-1544

Authors: Ricardo Colomo-Palacios, Eduardo Fernandes, Marc Sabbagh, Antonio Seco

Abstract: Cloud systems have shifted traditional on-premise software products towards new and service oriented solutions. In order to adapt to this new trend, traditional software vendors are facing a necessary evolution towards service oriented software products. This software evolution is quite complex and full of problems. This paper presents lessons learned and the issues that emerged in a project aimed to adapt Meta 4' PeopleNet solution to adopt a cloud computing approach. This project, designed as a two-step approach, presents a set of issues that are analyzed in this paper, namely: Software evolution, Software processes and Technology and Personnel issues. The resultant conclusions, that highlight the importance of people in this software evolution, are useful for companies facing a product evolution process towards cloud oriented environments.

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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-017-11-1572

Authors: Leo Ordinez, David Donari, Rodrigo Santos, Javier Orozco

Abstract: In this paper, the Behavioral Importance Priority Server (BIPS) algorithm is proposed to schedule sets of hard/soft real-time tasks. The mechanism postpones or advances the execution of the next instance of a task according to the value obtained from a function properly associated to the behavior of the task; as a consequence, there is a flexible adaptation of the bandwidth required by each server. A synchronization method is introduced to prevent deadlocks and priority inversions in the case of sets of tasks sharing resources along with the necessary and sufficient conditions for the schedulability analysis. A software framework proposing an abstract architecture of a system based on BIPS is also presented. The BIPS software framework intends to bridge the gap between theoretical scheduling aspects and the actual implementation of them. Since BIPS is capable of managing very different sets of tasks, it covers a wide variety of applications found in the real world.

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DOI: 10.3217/jucs-016-14-1826

Authors: Václav Dvořák, Petr Mikušek

Abstract: Assigning one (more) shared resource(s) to several requesters is a function of arbiters (allocators). This class of decision-making modules can be implemented in a number of ways, from hardware to firmware to software. The paper presents a new computer-aided technique that can produce representations of arbiters/allocators in a form of a Multi-Terminal Binary Decision Diagram (MTBDD) with close to minimum cost and width. This diagram can then serve as a prototype for a cascade of multiple-output look-up tables (LUTs) that implements the given function, or for efficient firmware implementation. The technique makes use of iterative decomposition of integer functions of Boolean variables and a variable-ordering heuristic to order variables. The LUT cascades lead directly to the pipelined design, simplify wiring and testing and can compete with the traditional FPGA design in performance and with PLA design in chip area.

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DOI: 10.3217/jucs-016-05-0686

Authors: Philip Ginzboorg, Valtteri Niemi

Abstract: We prove that two conditions are sufficient, and with three exceptions also necessary, for reachability of any position in restricted walk on integers in which the sizes of the moves to the left and to the right are constant but need not be equal. A method to compute the length of the shortest path between any two positions, as well as a shortest path algorithm when the reachability conditions are true are given. Also a complete characterization for Hamiltonian restricted walks between absorbing boundaries is given.

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DOI: 10.3217/jucs-015-12-2353

Authors: Ioannis Nikolakopoulos, Charalampos Patrikakis, Antonio Cimmino, Martin Bauer, Henning Olesen

Abstract: In this paper, we present a user profile definition scheme featuring context awareness. Though the scheme has been designed to meet the needs of web applications deployed over heterogeneous devices, emphasis is given in the deployment of the profile scheme over Personal Networks (PNs), as the personalization of the deployed applications and services in PN environments is of great importance. The proposed scheme is presented as part of an integrated framework for user profile management that takes into account (and is therefore compliant to) the existing standardization attempts. The overall architecture and description of the profile management framework, taking into account security issues inside Personal Networks, is presented. The paper concludes by showcasing how user profiles have been incorporated in a selected pilot service of the EU IST research project MAGNET Beyond.

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DOI: 10.3217/jucs-015-08-1563

Authors: Joaquín Entrialgo, Javier García, José Díaz, Daniel García

Abstract: In real-time systems, temporal behaviour is as important as functional behaviour, so several techniques have been especially developed for these systems. Stochastic analysis techniques model the execution time of tasks as random variables and constitute a very powerful tool to study the temporal behaviour of real-time systems. However, as they can not avoid all the timing bugs in the implementation, they must be combined with measurement techniques in order to gain more confidence in the implemented system. This paper presents a monitoring tool which can measure real-time systems developed using POSIX. The corresponding analysis and a visualization tool that makes it possible to find errors easily is also introduced. In order to find bugs in the timing behaviour of the system when an stochastic analysis technique is used, two metrics, called "pessimism" and "optimism", are proposed. They are based on two random variables, the optimistic and the pessimistic execution time, which are also introduced in this paper. These metrics are used in the debugging tools to compare the model and the measured system in order to find errors. The metrics are examined in four case studies.

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DOI: 10.3217/jucs-014-01-0088

Authors: Andrés Neyem, Sergio Ochoa, José Pino

Abstract: Advances in wireless communication and mobile computing extend collaboration scenarios. Mobile workers using computing devices are currently able to collaborate in order to carry out productive, educational or social activities. Typically, collaborative applications intended to support mobile workers involve some type of centralized data or services, because they are designed to work on infrastructure supported wireless networks. This centralization constrains the collaboration capabilities in ad-hoc communication cases. This paper introduces the concept of Service-Oriented Mobile Unit (SOMU) in order to reduce such limitation. SOMU is an autonomous software infrastructure running on a computing device; it is able to be integrated to ad-hoc networks and it can interoperate with other mobile units in ad-hoc collaboration scenarios. In addition, the paper presents the challenges faced when designing and implementing the SOMU platform. It also describes an application developed on SOMU.

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DOI: 10.3217/jucs-013-03-0363

Authors: Javier Díaz, Eduardo Ros, Rafael Rodriguez-Gomez, Begoña Pino

Abstract: Motion estimation from image sequences is a complex problem which requires high computing resources and is highly affected by changes in the illumination conditions in most of the existing approaches. In this contribution we present a high performance system that deals with this limitation. Robustness to varying illumination conditions is achieved by a novel technique that combines a gradient-based optical flow method with a non-parametric image transformation based on the Rank transform. The paper describes this method and quantitatively evaluates its robustness to different illumination changing patterns. This technique has been successfully implemented in a real-time system using reconfigurable hardware. Our contribution presents the computing architecture, including the resources consumption and the obtained performance. The final system is a real-time device capable to computing motion sequences in real-time even in conditions with significant illumination changes. The robustness of the proposed system facilitates its use in multiple potential application fields.

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DOI: 10.3217/jucs-013-02-0224

Authors: Iwan Tabakow

Abstract: This paper describes a method of using Petri net P-invariants in system diagnosis. To model this process a net oriented fault classification is presented. Hence, the considered discrete event system is modelled by a live, bounded, and reversible place-transition Petri net. The notions of D-partition of the set of places P of a given place-transition net N and net k-distinguishability are first introduced. Next these two notions are extended to the set of all vertices, i.e. places and transitions of N. So the problem of fault identification of the vertices of N is transformed as a problem of fault identification of the places of a new net N´ called a net simulator of N. Any transition in N´ is assumed to be fault-free. Then the corresponding net place invariants are computed. The system k-distinguishability measure is obtained in a unique way from the place-invariant matrix. For a large value of k, the system model is extended by using some set of additional places called test points and at the same time preserving the original net properties. To obtain a 1-distinguishable net the notion of a marked graph component is used. It is shown a sufficient condition for 1-distinguishability of an arbitrary place-transition net and a corresponding algorithm is presented. Next two different diagnosis test strategies are discussed, i.e. combinational and sequential fault diagnosis. Corresponding (single) place and transition fault models are introduced. The complexity of the proposed method depends on the effectivity of the existing algorithms for computation of the P-cover, i.e. the set of P-invariants covering N. The proposed approach can be extended for higher level Petri nets, e.g such as coloured nets or also to design self-diagnosable circuit realisations of Boolean interpreted Petri nets. Several examples are given.

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DOI: 10.3217/jucs-012-09-1128

Authors: Balázs Benyó, Miklós Hatwágner, Tamás Heckenast, Katalin Kovács, Ágnes Varga, Norbert Varjasi

Abstract: ENUM is a technology based on a procedure that assigns a sequence of traditional telephone numbers to Internet domain names. It specifies a rule that makes it possible to relate a domain to a telephone number without any risk of ambiguity. This domain can then be used to identify various communication services like fax, mobile phone numbers, voice-mail systems, e-mail addresses, IP telephone addresses, web pages, GPS coordinates, call diverts or unified messaging. In our paper we deal with three main problem areas in connection with the business model of the ENUM service and with the introduction of new services, i.e. the questions of tariffs, legal regulations and financial return. For the ENUM procedure to spread out in use specific services have to be implemented that can exploit the advantages of the ENUM and efficient methods have to be elaborated to base existing services on ENUM. We will outline the two new services invented by our group and that we have implemented in our project.

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DOI: 10.3217/jucs-012-04-0395

Authors: Nadia Nedjah, Luiza Mourelle

Abstract: In this paper, we propose a methodology based on genetic programming to automatically generate hardware designs of substitution boxes necessary for many cryptosystems such as DES encryption system. We aim at evolving minimal hardware specifications, which minimise both space (i.e. required gate number), response time (i.e. encryption and decryption time) and dissipated power. We compare our results against existing and well-known designs, which were produced by human designers using conventional methods.

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DOI: 10.3217/jucs-012-01-0030

Authors: Haiying Zhou, Kun Hou, Laurent Gineste, Christophe Vaulx, Jean Ponsonnaille

Abstract: More than 60,000 people die suddenly each year in France due to cardiac arrhythmias. The current techniques used to diagnose cardiac arrhythmias such as HOLTER, R.TEST and telemetry system are partially efficient owing to the limitation of the duration of monitoring. This paper presents a new system dedicated to real-time cardiac arrhythmias tele-assistance and monitoring. This system is generally composed of 4 main configurable elements: wireless ECG sensor, local access unit, remote centre server, and remote surveillance terminal. The main technical challenges of this system include three aspects: a real-time automatic ECG diagnostic algorithm, an embedded real-time multi-task operating system, and a real-time reliable telemedicine communication protocol. This paper gives our solutions to these problems and specifies the technical details. Currently, this system has been evaluated on thirty patients at the CHRU of Gabriel Montpied hospital (Clermont-Ferrand, France) and also been used to test the athletes' cardiac status during the physical exercises. The performance results show that this system meets fully the requirements of real-time cardiac monitoring and diagnosing application and can be used as a long-term cardiac healthcare equipment.

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DOI: 10.3217/jucs-010-09-1123

Authors: Maziar Goudarzi, Shaahin Hessabi, Alan Mycroft

Abstract: We present an embedded_system design flow, discuss its details, and demonstrate its advantages. We adopt the object_oriented methodology for the system_level model because software dominates hardware in embedded systems and the object_oriented methodology is already established for software design and reuse. As the building_block of system implementation, we synthesise application_specific processors that are reusable, through programming, for several related applications. This addresses the high cost and risk of manufacturing specialised hardware tailored to only a single application. Both the processor and its software are generated from the model of the system by the synthesis and compilation procedures provided. We observe that the key point in object_oriented methodology is the class library, and hence, we implement methods of the class library as the instruction_set of the processor. This allows the processor to be synthesised just once, but, by programming, to be reused several times and specialised to new applications that use the same class library. An important point here is that the processor allows its instructions to be selectively overridden by software routines, this not only allows augmentation of processor capabilities in software, but also enables a structured approach to make software patches to faulty or outdated hardware. A case study illustrates application of the methodology to various applications modelled on top of a common basis class library, and moreover, demonstrates new application_specific opportunities in power management (and area_management for FPGA implementations) resulting from the structure of the processor based on de_activation of unused features.

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DOI: 10.3217/jucs-010-02-0120

Authors: Bernhard Rinner, Martin Schmid, Reinhold Weiss

Abstract: In this paper we present PEPSY, a novel prototyping environment for multi-DSP systems, with the primary goal to support the design and implementation of parallel digital signal processing (DSP) applications subject to various design constraints. Given a specification of the prototyping problem in the form of an application model, a hardware model and mapping constraints, PEPSY automatically maps and schedules the DSP application onto the multi-processor system and synthesizes the complete code for each processor. A detailed performance model of the parallel application is an integral part of PEPSY. Important performance parameters such as computation and communication times as well as memory consumption can be estimated prior to the implementation. PEPSY not only solves the standard mapping and scheduling problem, but it is also able to explore various important design goals for embedded systems and DSP applications such as minimizing memory and power consumption and enforcing the timeliness of tasks. Two complex case studies demonstrate the feasibility of our prototyping environment.

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DOI: 10.3217/jucs-008-01-0002

Authors: Egon Börger

Abstract: The research belonging to the Abstract State Machines approach to system design and analysis is surveyed and documented in an annotated ASM bibliography. The survey covers the period from 1984, when the idea for the concept of ASMs (under the name dynamic or evolving algebras or structures) appears for the first time in a foundational context, to the year 2001 where a mathematically well-founded, practical system development method based upon the notion of ASMs is in place and ready to be industrially deployed. Some lessons for the future of ASMs are drawn.

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DOI: 10.3217/jucs-007-01-0089

Authors: Jürgen Ruf

Abstract: In this paper we present the real-time verification and analysis tool RAVEN. RAVEN is developed for verifying timed systems on various levels of abstraction. It integrates a real-time model checker for real-time specifications, it offers algorithms for analyzing critical delay times, for inspecting data values and event occurrences and for detecting dead_locks and live-locks. The counter example generator provides helpful information for error recovering by printing system execution paths (failing a given specification) to the integrated wave_form browser. All included algorithms are based on a common data structure enabling a compact representation and possibilities for acceleration. By some examples we show that our approach outperforms some state-of-the-art verification tools.

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DOI: 10.3217/jucs-006-07-0704

Authors: Graeme Smith, Colin Fidge

Abstract: System requirements frequently change while the system is still under development. Usually this means going back and revising the requirements specification and redoing those development steps already completed. In this article we show how formal requirements can be allowed to evolve while system development is in progress, without the need for costly redevelopment. This is done via a formalism which allows requirements engineering steps to be interleaved with formal development steps in a manageable way. The approach is demonstrated by a significant case study, the Light Control System.

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DOI: 10.3217/jucs-006-07-0679

Authors: Martin Kronenburg, Christian Peper

Abstract: Forest is a requirements engineering approach designed to support the creation of precise and intelligible problem specifications of reactive systems. It integrates a product model, a process model, and an editing tool. In this paper, we present the results of applying the Forest approach to the Light Control Case Study. This includes the presentation of excerpts of the resulting problem specification, as well as the discussion of the strengths and shortcomings of the Forest approach.

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DOI: 10.3217/jucs-006-04-0460

Authors: L. Steggles

Abstract: Second-order algebraic methods provide a natural and expressive formal framework in which to develop correct computing systems. In this paper we consider using second-order algebraic methods to specify real-time systems and to verify their associated safety and utility properties. We demonstrate our ideas by presenting a detailed case study of the railroad crossing controller, a benchmark example in the real-time systems community. This case study demonstrates how real-time constraints can be modelled naturally using second-order algebras and illustrates the substantial expressive power of second-order equations.

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DOI: 10.3217/jucs-001-12-0811

Authors: Marco Platzner, Bernhard Rinner, Reinhold Weiss

Abstract: Constraint satisfaction is very common in many artificial intelligence applications. This paper presents results from parallelizing constraint satisfaction in a special application --- the algorithm for qualitative simulation QSim [Kuipers 94]. A parallel-agent based strategy (PAB) is used to solve the constraint satisfaction problem (CSP). Two essential steps of PAB are studied in more detail to achieve a good performance of the parallel algorithm. Partitioning heuristics to generate independent parts of the overall search space are investigated. Sequential CSP algorithms are compared in order to reveal the most efficient one for QSim. The evaluation of these heuristics and algorithms is based on runtime measurements using CSPs traced from QSim. These runtimes allow a best- and worst-case estimation of the expected speedup of the parallel algorithms. The comparison of sequential CSP algorithms leads to following strategy for solving partitioned problems. Less complex problems are solved with simple backtracking, and more complex models are solved with graph-directed backjumping (GBJ).

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