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Network connectivity, as a fundamental issue in a wireless sensor network(WSN), has been receiving considerable attention during the past decade. Most works focused on how to maintain full connectivity while conserving network resources. However, full connectivity is actually a sufficient but not necessary condition for many WSNs to communicate and function successfully. In addition, full connectivity...
NS(Simulator Network) is an object-oriented visual simulator based on large-scale discrete event. It simulates not only the transmission of network data and topology architecture, but also all kinds of IP network circumstance. This paper describes the architecture and characteristics of NS, and also gives the technique and the general process based on NS. The instance of a streaming media applications-based...
Partitioning network, especially some DTN, can use Message Ferry(MF) scheme to restore network connection. Message TTL describes the maximum delay tolerance of transmission and messages with out-of-date TTL should be dropped. In this paper, we will study the problem of how to design the ferry's moving route dynamically to get high message delivery ratio under the constraint of message TTL, which we...
A latency-hiding algorithm for the parallelization of large scale agent-based model simulations (ABMS) on parallel/distributed computing platform is proposed. The key idea of this algorithm is using redundant computations to hide communication latencies. An analytical model for this algorithm is presented to tell how to select R value to reach the best speedup. Compared to B+2R algorithm [1], theoretical...
We discuss our approach to federating dissimilar discrete event simulations, leveraging the strengths and design goals of both, to produce a packet-level detailed network model federated with a component-level detailed input-queuing router model. All existing network simulation tools that we are aware of incorporate a very simplistic model for the flow of packets through a router. The simplistic model...
Aimed to reduce the overheads using the Time Management (TM) in HLA based distributed simulations, the TM based on publish-subscribe topology information is investigated. The condition under which the message may be received before its causal predecessor is firstly analyzed. And then, the TM algorithms using vector clock are put forward, in which the condition is judged before the clock is comparing...
The synchronous programming model is perfect for modeling, simulation, verification and implementation of reactive systems. While this paradigm can be directly implemented as hardware circuits, multithreaded software implementations are typically based on asynchronous threads. For this reason, an efficient multithreaded software implementation of a synchronous program requires a so-called desynchronization...
There has been significant interest in model based testing (MBT), in which testing is based on a model of the required behaviour of the system under test (SUT) or some aspect of this required behaviour. Most MBT approaches use statebased languages such as input output transition systems (IOTSs) (see, for example, [1]) or finite state machines (FSMs) (see, for example, [2], [3]). Given a model M, it...
By using a continuation theorem based on coincidence degree, we study the global existence of positive periodic solution of the periodic Lotka-Volteraa food chain model with delays. A set of easily verifiable sufficient conditions are obtained, some new results obtained.
A three-stage-structured prey-predator system with predator density dependent time delay is considered. The positive and uniformly bounded of the solution of the system are obtained, and the conditions for the system occurring global Hopf bifurcation is given. Finally, numerical simulations and brief conclusion are given.
In this paper, a non-autonomous predator-prey diffusion system of two species with depositings and ratio-dependence is investigated. By using Comparability Theorem and Mawhin's continuation theorem of coincidence degree theory, a set of easily verifiable sufficient conditions are obtained to guarantee the permanent and existence of positive periodic solutions of the system. Some new results obtained.
Space Wire is a standard of on-board networks for satellites promoted by the ESA. As the ESA plans to use Space Wire as the sole network for both critical and non-critical traffics, network designers need tools to check that all the critical messages meet their deadlines. We previously proposed two such tools to compute an upper-bound on the worst-case end-to-end delay of a packet traversing a Space...
In the article we propose a method of improving ITU-T E-model MOS estimate of VoIP call quality. The improvement consists of including the effects of network jitter as measured and distributed in RTCP packets; jitter buffer size at receiver and codec packetization settings as input parameters of E-Model. Our method uses Pareto/D/1/k system for modeling general VoIP input traffic stream interarrival...
This paper discusses the robustness of nonlinear model predictive control (NMPC) based on sub-optimal solution obtained under reduced precision solution (RPS) criteria. NMPC needs to solve the optimal control problem (OCP) quickly and the input is injected to the controlled plant in time. Traditional convergence criteria in optimization algorithms usually cost excessive long computation time with...
Parallelization of big-data analytics services over a federation of heterogeneous clouds has been considered to improve performance. However, contrary to common intuition, there is an inherent tradeoff between the level of parallelism and the performance for big-data analytics principally because of a significant delay for big-data to get transferred over the network. The data transfer delay can be...
In this paper we briefly describe multi-agent system architectures that are proved to be suited to address problems which simultaneously are of a Distributed, Decentralized and Dynamic nature. Two clearly different scenarios are used to show how the multi-agent system paradigm can be used to cope with realistic situations which are eiter mainly cooperative or mainly competitive and, thus, asking for...
The non-recurrent congestion caused by incident happens frequently in urban traffic network and influences normal operation of traffic system greatly, so that studying on congestion control strategies under propagation of non-recurrent congestion is very important. The aim of this dissertation is to investigate the spatio-temporal distribution of traffic flow and location of variable message sign...
We propose a novel admission control policy for database queries. Our methodology uses system measurements of CPU utilization and query backlogs to determine interference between queries in execution on the same database server. Query interference may arise due to the concurrent access of hardware and software resources and can affect performance in positive and negative ways. Specifically our admission...
In this paper we present the use of a SystemC-based design environment called DESYRE to the simulation of a modern elevator system designed by Otis Elevator Company for large scale buildings. We describe the construction of the virtual prototype of a scalable elevator system based on the CAN communication protocol. We show the tuning and validation of the simulated model against a test system composed...
In this paper, we design an efficient method of simulating wireless networks that use CSMA/CA-based protocols in the MAC layer. In the method, a stochastic model to estimate the CSMA/CA frame transmission delay is naturally incorporated into the conventional fully event-based model. The stochastic model can simplify the interactions between a frame transmitter and its surrounding nodes, which alleviates...
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