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This paper proposes an approach to modelling and analysis of distributed real-time actor systems, which is based on the Uppaal statistical model checker (SMC). SMC was chosen because it automatizes simulations, offers a temporal logic language to formalize specifications and exploits statistical techniques to infer quantitative measures about a model. The approach is integrated in a system life-cycle...
This paper is an evaluation of UML for Real-Time (UML-RT) for modelling Self-Adaptive Software (SAS) systems. Using a systematic review of the different features of UML-RT (optional capsules, SAP/SPP communication, hierarchical state machines, etc.), we analyse the suitability of the language for modelling structural and behavioural adaptations at design-and run-time. We evaluate these features in...
Content streaming is a mechanism used to distribute static geometry data to users of a virtual environment in real-time. Although most existing content streaming mechanisms have shown to meet their run-time performance requirements, they have an underlying constraint on the quality of 3D data that can be streamed. This restriction stems from the fact that most existing content streaming mechanisms...
Messages traversing a network commonly experience waiting times due to sharing the forwarding resources. During those times, the crossed systems must provide sufficient buffer space for queueing messages. Network Calculus (NC) is a mathematical methodology for bounding flow delays and system buffer requirements. The accuracy of these performance bounds depends mainly on two factors: the principles...
Cyber-physical systems (CPS) are large scale systems highly integrated with the physical environment. Given the changing nature of physical environments, CPS must be able to adapt on-line to new situations while preserving their correct operation. Correctness by construction relies on using formal tools, which suffer from a considerable computationaloverhead especially if executed on-line. As the...
Predicting the performance of cloud services is intrinsically hard. In this work, we pursue an approach based upon statistical learning, whereby the behaviour of a system is learned from observations. Specifically, our testbed implementation collects device statistics from a server cluster and uses a regression method that accurately predicts, in real-time, client-side service metrics for a video...
Content-centric networking (CCN) is a new paradigm that can access content and services using naming. Applying CCN to the LTE network can be an effective way to provide an optimal content delivery performance in the mobile environment. In order to visualize and demonstrate the performance of CCN in the LTE environment, we propose a new direct code execution simulation framework which integrates the...
Traditionally, the evaluation of surgical procedures in VR simulators have been restricted to their individual technical aspects, and disregarded the procedures carried out by teams. However, some decision models have been proposed in order to be incorporated and support the collaborative training evaluation process of surgical teams in Collaborative Virtual Environments (CVEs). This paper aims to...
Complex contemporary systems contain multiple applications, some which have firm real-time requirements while others do not. These applications are deployed on multi-core platforms with shared resources, such as processors, interconnect, and memories. However, resource sharing causes contention between sharing applications that must be resolved by a resource arbiter. Time-Division Multiplexing (TDM)...
This paper develops new schedulability bounds for a simplified MapReduce workflow model. MapReduce is a distributed computing paradigm, deployed in industry for over a decade. Different from conventional multiprocessor platforms, MapReduce deployments usually span thousands of machines, and a MapReduce job may contain as many as tens of thousands of parallel segments. State-of-the-art MapReduce workflow...
This paper presents the methodology for the synthesis of real-time applications for the Infrastructure as a Service (IaaS) model of cloud computing. We assume that the function of the application is specified as a set of distributed echo algorithms with real-time constraints. Then our methodology schedules all tasks on available cloud infrastructure minimizing the total costs of the IaaS services,...
Computational Steering (CS) of numerical simulations has been developed over the last three decades. While it has succeeded in some of its chief aims, the uptake and impact of CS has not been as great as anticipated. This paper aims to investigate the reasons for this, and from this analysis to provide an enhanced CS framework, taking into account both modern developments in end-user devices and changes...
In the recent years we are experiencing the rapid growth of crowd sourcing systems, in which "human workers" are enlisted to perform tasks more effectively than computers, and get compensated for the work they provide. The common belief is that the wisdom of the "human crowd" can greatly complement many computer tasks which are assigned to machines. A significant challenge facing...
Developing microgrids is an efficient approach to increasing the penetration of distributed generation (e.g., gas-turbine, wind turbine and photovoltaic power, etc.) in a power system. A microgrid can be operated by centralized control, autonomous control or multi-agents. Among all, a control center can provide a more reliable operation using many experiences related to traditional industrial power...
A cyber-physical system is a large and complex infrastructure. Due to the increasing connectivity, the power and cyber systems become more interdependent. Models of the interactions are needed between the power devices and information and communication technology (ICT). A broad range of cyber attacks has become a serious concern. Cyber attacks must be simulated to analyze the consequences on the power...
Since Trojan has been used widely in various applications, modern Trojan requires a stronger anti-tracing performance than before. As an attempt seeking beneficial result, this paper proposes a new Trojan communication model based on Internet Relay Chat (IRC) and Webmail system. IRC chat channel is designed to transfer commands and Webmail system is applied to store data. Because of this design, it...
Porting of the enterprise IT infrastructure to the cloud based solutions has raised many issues particularly related to the cloud computing. Every enterprise wants to utilize reliable cloud infrastructure with a high level of performance by keeping cost as low as possible. We need a model to achieve this. In this paper, we introduce a framework, which increases the performance of the application and...
A new generation of distributed real-time systems (DRTS) is based on heterogeneous models of computation and communication and is associated with flexible real-time constraints. Classical design flows based on realtime scheduling theory display important limitations related to the restrictive assumption on the system model. On the other hand, formal verification of timed automata is far more general,...
In order to overcome the shortcomings brought by the narrow bandwidth of wireless network and limited computing ability of mobile terminals, this paper mainly proposes a 3D model transmission and interactive real-time rendering method over wireless local area network. Firstly, an optimized model simplified algorithm is presented for preserve the visually important vertices longer than other vertices...
This paper deals with different types of configurations and network-architecture models used for multi-party conferencing in VoIP. A comparison of multi-party conferencing models is presented based on the bandwidth used by the Real Time Protocol (RTP) streams, quality degradation due to trans-coding if any, etc. Also, an efficient and simple architectural design of a media engine for decentralized...
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