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SN Computer Science (20191013) 1: 17
, October 13, 2019
By
Gorawski, Michał; Grochla, Krzysztof
The infrastructure managed by Smart City systems includes mainly linear structures, such as pipelines, electric power lines, railway lines, etc.. In this paper, we propose the transcription of linear infrastructure to graph representation and storing needed metadata in a graph database, merged with the traditional relational database used for device management. Such an approach enables fast acquisition of data about infrastructure’s properties and allows merging information about the structure of the managed infrastructure with information devices’ properties and statistics. We develop a graph generator that generates virtual network basing on representative examples of linear infrastructure, incorporation of a data from existing metering systems with the generated structure, which automates the deployment and allows to evaluate the performance of Smart City monitoring and management system. We present results of performance tests that show and the creation time of graph database structures in Neo4j and the difference between the performance of the Microsoft SQL Server database and the Neo4j database in a few Smart City use cases. The results show that the use of the graph database to execute queries related to linear infrastructure allows decreasing the response time up to 9 times.
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SN Computer Science (20191029) 1: 18
, October 29, 2019
By
Arcari, Leonardo; Gribaudo, Marco; Palermo, Gianluca; Serazzi, Giuseppe
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Carnavigation system was recently established as an imperative utility for modern navigation on road networks. The rising wave of selfdriving cars along with an increasing demand for realtime traffic data is expected to generate massive growth of routing requests and processing time on large graphs representing the urban networks. Therefore, larger and more powerful computing infrastructures are required. In the context of smart cities, new, dynamic solutions are needed to deliver highquality carnavigation services, powered by municipal trafficmonitoring data, capable of handling such a vast expected demand with reasonable employment of financial resources. In this work, we introduce an adaptive carnavigation system and its performance model used to tune the size of the computing infrastructure as a function of the characteristics of the environment considered. The model has been validated for a smart city environment using the data collected on the Milan urban area.
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SN Computer Science (20191019) 1: 110
, October 19, 2019
By
Phi, Tien Cuong; Muzy, Alexandre; ReynaudBouret, Patricia
Eventscheduling algorithms can compute in continuous time the next occurrence of points (as events) of a counting process based on their current conditional intensity. In particular, eventscheduling algorithms can be adapted to perform the simulation of finite neuronal networks activity. These algorithms are based on Ogata’s thinning strategy (Ogata in IEEE Trans Inf Theory 27:23–31, 1981), which always needs to simulate the whole network to access the behavior of one particular neuron of the network. On the other hand, for discrete time models, theoretical algorithms based on Kalikow decomposition can pick at random influencing neurons and perform a perfect simulation (meaning without approximations) of the behavior of one given neuron embedded in an infinite network, at every time step. These algorithms are currently not computationally tractable in continuous time. To solve this problem, an eventscheduling algorithm with Kalikow decomposition is proposed here for the sequential simulation of point processes neuronal models satisfying this decomposition. This new algorithm is applied to infinite neuronal networks whose finite time simulation is a prerequisite to realistic brain modeling.
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SN Computer Science (20190708) 1: 114
, July 08, 2019
By
Tran, Cuong Ngoc; Danciu, Vitalian
Softwaredefined networks (SDN) replacing the network appliances of traditional networks with logically centrally deployed applications, which are able to introduce the network function they implement into any element in the network. This flexibility renders SDN prone to conflict. We demonstrate conflict between applications in a laboratory setting to emphasize the importance of conflict detection in production networks. The evaluation of an analytical approach shows substantial obstacles in the general case. Our experimental approach produces conflict classes and detection patterns by means of studying network behaviour in the presence of multiple applications and traffic profiles being applied to different topologies. Based on such experiments, we illustrate the extraction of conflict patterns and their application to conflict detection in new situations.
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SN Computer Science (20200121) 1: 119
, January 21, 2020
By
Bernal, Emer; Castillo, Oscar ; Soria, José; Valdez, Fevrier
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In this work, a fuzzy method for dynamic adjustment of parameters in galactic swarm optimization is presented. Galactic swarm optimization is based on the movement of stars and galaxies in the universe, as well as their attractive influence allowing the use of multiple cycles of exploration and exploitation to solve complex optimization problems. It has been observed in the literature that the utilization of fuzzy systems for dynamic adjustment of parameters in metaheuristic algorithms produces good results when compared to using fixed parameters in the algorithms. In this work, the adjustment of the c_{3} and c_{4} parameters is made through the use of fuzzy systems because these parameters have a significant role in the operation of galactic swarm optimization. We tested the fuzzy approach with a set of benchmark mathematical functions and with the fuzzy controller of the water tank problem to measure the performance. Finally, a comparison of the results is presented among the proposed method and other metaheuristics.
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SN Computer Science (20191019) 1: 118
, October 19, 2019
By
Kar, Udit Narayana ; Sanyal, Debarshi Kumar
Devicetodevice (D2D) communication is rapidly evolving into a viable method of information exchange in a cellular network. It has a very low endtoend latency and can increase spectral efficiency of a cellular network. The latest releases of 3GPP specification have given considerable attention to standardize this mode of communication and integrate it in the ecosystem of LTE advanced. This will give more impetus to the development of D2D technologies and their adoption by mobile operators. This paper presents a discussion and critical analysis of the main features of D2D communication as defined in Release 12 and subsequent releases of 3GPP specifications.
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SN Computer Science (20191122) 1: 19
, November 22, 2019
By
Baruchel, Thomas
The recursion tree resulting from Karatsuba’s formula is built here using an interleaved splitting scheme rather than the traditional left/right one. This allows an easier access to the nodes of the tree and some of them are initially flattened all at once into a single recursive formula. The whole tree is then flattened further into a convolution formula involving less elementary multiplications than the usual Cauchy product—leading to iterative (rather than recursive) implementations of the algorithm. Unlike the traditional splitting scheme, the interleaved approach may also be applied to infinite power series, and the corresponding formulas are also given.
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SN Computer Science (20191207) 1: 112
, December 07, 2019
By
Barbieri, E.; Capocchi, L. ; Santucci, J. F
Discreteevent modeling and simulation and machine learning are two frameworks suited for system of systems modeling which when combined can give a powerful tool for system optimization and decision making. One of the less explored application domains is finance, where this combination can propose a driven tool to investor. This paper presents a discreteevent specification as a universal framework to implement a machine learning algorithm into a modular and hierarchical environment. This approach has been validated on a financial leverage effect based on a Markov decisionmaking policy.
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SN Computer Science (20191221) 1: 117
, December 21, 2019
By
Arvanitaki, Antonia; Pappas, Nikolaos ; Mohapatra, Parthajit; Carlsson, Niklas
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In this paper, we consider the twouser broadcast channel with security constraints. We assume that a source broadcasts packets to two receivers, and that one of them has secrecy constraints, i.e., its packets need to be kept secret from the other receiver. The receiver with secrecy constraint has fullduplex capability, allowing it to transmit a jamming signal to increase its secrecy. We derive the average delay per packet and provide simulations and numerical results, where we compare different performance metrics for the cases when both receivers treat interference as noise, when the legitimate receiver performs successive decoding, and when the eavesdropper performs successive decoding. The results show that successive decoding provides better average packet delay for the legitimate user. Furthermore, we define a new metric that characterizes the reduction on the success probability for the legitimate user that is caused by the secrecy constraint. The results show that secrecy poses a significant amount of packet delay for the legitimate receiver when either receiver performs successive decoding. We also formulate an optimization problem, wherein the throughput of the eavesdropper is maximized under delay and secrecy rate constraints at the legitimate receiver. We provide numerical results for the optimization problem, where we show the tradeoff between the transmission power for the jamming and the throughput of the nonlegitimate receiver. The results provide insights into how channel ordering and encoding differences can be exploited to improve performance under different interference conditions.
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SN Computer Science (20190726) 1: 115
, July 26, 2019
By
Rivera, Victor ; Meyer, Bertrand
The aliasing question (can two reference expressions point, during an execution, to the same object?) is both one of the most critical in practice, for applications ranging from compiler optimization to programmer verification, and one of the most heavily researched, with many hundreds of publications over several decades. One might then expect that good offtheshelf solutions are widely available, ready to be plugged into a compiler or verifier. This is not the case. In practice, efficient and precise alias analysis remains an open problem. We present a practical tool, AutoAlias, which can be used to perform automatic alias analysis for objectoriented programs. Based on the theory of “duality semantics”, an application of Abstract Interpretation ideas, it is directed at objectoriented languages and has been implemented for Eiffel as an addition to the EiffelStudio environment. It offers variableprecision analysis, controllable through the choice of a constant that governs the number of fixpoint iterations: a higher number means better precision and higher computation time. All the source code of AutoAlias, as well as detailed results of analyses reported in this article, are publicly available. Practical applications so far have covered a library of data structures and algorithms and a library for GUI creation. For the former, AutoAlias achieves a precision appropriate for practical purposes and execution times in the order of 25 s for about 8000 lines of intricate code. For the GUI library, AutoAlias produces the alias analysis in around 232 s for about 150,000 lines of intricate code.
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