DOI: 10.3217/jucs-021-02-0248

Authors: Daniel Perez-Gonzalez, Raimundo Díaz-Díaz

Abstract: Social, technological and economic changes, citizen demand of services modernization, new ICT developments related to the Internet of Things and an economic situation that urges more efficient public administrations, have allowed the adoption of ICT by municipalities in order to provide public services. All the foregoing constitutes a boost of the smart city concept, which is considered in the scientific literature mainly from a technical point of view, overlooking deeper analysis on the specific services being provided by means of smart technologies. The current research identifies services provided using smart technologies at 26 Spanish smart cities and the degree of smart development of those cities based on which services provide. The results highlight that the services most widely implemented are those that allow direct reductions in local administration expenditure. On the other hand, the remaining services enjoy greater perspectives of future development. Additionally, three groups of smart city development have been identified, which allows benchmarking analysis and enhances the exchange of information between the cities.

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DOI: 10.3217/jucs-020-13-1738

Authors: Davide Vega, Roc Meseguer, Felix Freitag, Sergio Ochoa

Abstract: Volunteer computing is a paradigm in which devices participating in a distributed environment share part of their resources to help others perform their activities. The effectiveness of this computing paradigm depends on the collaboration attitude adopted by the participating devices. Unfortunately for software designers it is not clear how to contribute with local resources to the shared environment without compromising resources that could then be required by the contributors. Therefore, many designers adopt a conservative position when defining the collaboration strategy to be embedded in volunteer computing applications. This position produces an underutilization of the devices’ local resources and reduces the effectiveness of these solutions. This article presents a study that helps designers understand the impact of adopting a particular collaboration attitude to contribute with local resources to the distributed shared environment. The study considers five collaboration strategies, which are analyzed in computing environments with both, abundance and scarcity of resources. The obtained results indicate that collaboration strategies based on effort-based incentives work better than those using contribution-based incentives. These results also show that the use of effort-based incentives does not jeopardize the availability of local resources for the local needs.

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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-018-13-1853

Authors: Musrrat Ali, Millie Pant, Atulya Nagar, Chang Ahn

Abstract: Insertion of a local search technique is often considered an effective mechanism to increase the efficiency of a global optimization algorithm. In this paper we propose and analyze the effect of two local searches namely; Trigonometric Local Search (TLS) and Interpolated Local Search (ILS) on the working of basic Differential Evolution (DE). The corresponding algorithms are named as DETLS and DEILS. The performances of proposed algorithms are investigated and compared with basic DE, modified versions of DE and some other evolutionary algorithms. It is found that the proposed schemes improve the performance of DE in terms of quality of solution without compromising with the convergence rate.

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DOI: 10.3217/jucs-018-09-1072

Authors: Hongyu Huang, Daqiang Zhang, Yanmin Zhu, Minglu Li, Min-You Wu

Abstract: The past few years have witnessed the growing interest in vehicular ad hoc networks(VANETs) and their potential applications for Internet of Things (IoT). Since the mobility model is crucial to simulation based researches of VANET, using a realistic mobility model can ensurethe consistency between simulation results and real deployments. Although there are many mobility models characterizing the movement of mobile nodes, none of them consider the behaviorof vehicles in a metropolitan scenario. In this paper, we present our study of extracting a mobility model for VANET from a large amount of real taxi GPS trace data. In order to capture charac-teristics of the urban vehicle network from microscopic to macroscopic aspects, we design three parameters and extract their values from the GPS trace data. Using this mobility model, we cangenerate the synthetic trace to simulate the movement of taxis in the urban area of a metropolis. The validation is carried through extensive comparisons between the synthetic trace and the realtrace. The results show that our mobility model has a good approximation with the real scenario.

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DOI: 10.3217/jucs-017-11-1605

Authors: Khaled Salah, Mojeeb-Al-Rhman Al-Khiaty, Rashad Ahmed, Adnan Mahdi

Abstract: Snort is the most widely deployed network intrusion detection system (NIDS) worldwide, with millions of downloads to date. PC-based Snort typically runs on either Linux or Windows operating systems. In this paper, we present an experimental evaluation and comparison of the performance of Snort NIDS when running under the two newly released operating systems of Windows 7 and Windows Server 2008. Snort's performance is measured when subjecting a PC host running Snort to both normal and malicious traffic. Snort's performance is evaluated and compared in terms of throughput and packet loss. In order to offer sound interpretations and get a better insight into the behaviour of Snort, we also measure the packet loss encountered at the kernel level. In addition, we study the impact of running Snort under different system configurations which include CPU scheduling priority given to user applications or kernel services, uni and multiprocessor environment, and processor affinity.

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DOI: 10.3217/jucs-016-21-3299

Authors: Khaled Salah, Mohamed Hamawi

Abstract: These days, commodity-off-the-shelf (COTS) hardware and software are used to build high-end and powerful workstations and servers to be deployed in today's local area networks of private homes and small- to medium-sized business. Typically, these servers are multipurpose and shared - running networking functionalities involving IP packet forwarding in addition to other CPU intensive applications. In this paper we study and investigate the impact of running CPU-bound applications on the performance of IP packet forwarding. We measure and compare the impact and performance for the two operating systems of choice for home and small-business users, namely Linux and Windows XP. The performance is studied in terms of key performance metrics which include throughput, packet loss, round-trip delay, and CPU availability. For our measurements, we consider today's typical home network hosts of modern processors and Gigabit network cards. We also consider different configuration setups and utilize open-source tools to generate relatively high traffic rates. Our empirical results show that Linux exhibits superior performance over Windows XP in terms of IP forwarding performance. Results also show that, unlike Windows XP, the IP forwarding performance of Linux is not significantly impacted by running CPU-bound applications.

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DOI: 10.3217/jucs-016-08-1056

Authors: Manuel J. Fernández Iglesias, Luis M. Álvarez Sabucedo

Abstract: Europe is currently transitioning to digital terrestrial television and isaimed to replace all analog infrastructures by 2012. Besides replacing all broadcasting networks in Europe, the transition requires updating household televisions andantennas. As with any major change, public administrations must keep citizens informed and provide support, especially when dealing with a communication mediumexpected to support a new portfolio of services and information. State-of-the-art technologies enable universal coverage in locations where television services are currentlyunavailable. This paper evaluates the transition to digital television in several European regions and analyzes novel approaches and solutions to achieving universal accessto digital television and citizen awarenes.

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