5,180 research outputs found

    Network emulation focusing on QoS-Oriented satellite communication

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    This chapter proposes network emulation basics and a complete case study of QoS-oriented Satellite Communication

    Assessing and augmenting SCADA cyber security: a survey of techniques

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    SCADA systems monitor and control critical infrastructures of national importance such as power generation and distribution, water supply, transportation networks, and manufacturing facilities. The pervasiveness, miniaturisations and declining costs of internet connectivity have transformed these systems from strictly isolated to highly interconnected networks. The connectivity provides immense benefits such as reliability, scalability and remote connectivity, but at the same time exposes an otherwise isolated and secure system, to global cyber security threats. This inevitable transformation to highly connected systems thus necessitates effective security safeguards to be in place as any compromise or downtime of SCADA systems can have severe economic, safety and security ramifications. One way to ensure vital asset protection is to adopt a viewpoint similar to an attacker to determine weaknesses and loopholes in defences. Such mind sets help to identify and fix potential breaches before their exploitation. This paper surveys tools and techniques to uncover SCADA system vulnerabilities. A comprehensive review of the selected approaches is provided along with their applicability

    Control/structure interaction design methodology

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    The Control Structure Interaction Program is a technology development program for spacecraft that exhibit interactions between the control system and structural dynamics. The program objectives include development and verification of new design concepts (such as active structure) and new tools (such as a combined structure and control optimization algorithm) and their verification in ground and possibly flight test. The new CSI design methodology is centered around interdisciplinary engineers using new tools that closely integrate structures and controls. Verification is an important CSI theme and analysts will be closely integrated to the CSI Test Bed laboratory. Components, concepts, tools and algorithms will be developed and tested in the lab and in future Shuttle-based flight experiments. The design methodology is summarized in block diagrams depicting the evolution of a spacecraft design and descriptions of analytical capabilities used in the process. The multiyear JPL CSI implementation plan is described along with the essentials of several new tools. A distributed network of computation servers and workstations was designed that will provide a state-of-the-art development base for the CSI technologies

    Smart container monitoring using custom-made WSN technology : from business case to prototype

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    This paper reports on the development of a prototype solution for tracking and monitoring shipping containers. Deploying wireless sensor networks (WSNs) in an operational environment remains a challenging task. We strongly believe that standardized methodologies and tools could enhance future WSN deployments and enable rapid prototype development. Therefore, we choose to use a step-by-step approach where each step gives us more insight in the problem at hand while shielding some of the complexity of the final solution. We observed that environment emulation is of the utmost importance, especially for harsh wireless conditions inside a container stacking. This lead us to extend our test lab with wireless link emulation capabilities. It is also essential to assess feasibility of concepts and design choices after every stage during prototype development. This enabled us to create innovative WSN solutions, including a multi-MAC framework and a robust gateway selection algorithm

    The state of peer-to-peer network simulators

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    Networking research often relies on simulation in order to test and evaluate new ideas. An important requirement of this process is that results must be reproducible so that other researchers can replicate, validate and extend existing work. We look at the landscape of simulators for research in peer-to-peer (P2P) networks by conducting a survey of a combined total of over 280 papers from before and after 2007 (the year of the last survey in this area), and comment on the large quantity of research using bespoke, closed-source simulators. We propose a set of criteria that P2P simulators should meet, and poll the P2P research community for their agreement. We aim to drive the community towards performing their experiments on simulators that allow for others to validate their results

    Satellite diversity system emulator

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    Current satellite telecommunication systems are facing growing demand, in particular for broadband markets. In order to reach higher data rate and minimize the cost per Mbps, upcoming VHTS systems are targeting Terabit capacity. One of the most promising solution is to dedicate the whole Ka band to the user links to maximize the user link capacity whereas the feeder links operate in Q/V bands. However, the use of these higher frequencies (in the Q/V bands) raises new challenges, because of the increased sensitivity of these bands to meteorological events that may affect gateways link budget, making them unable to handle any traffic during a rain event. A simple solution to this shortcoming for ensuring constant service to users is to add additional gateways to the system and perform a handover to a redundancy gateway when a nominal gateway faces too strong fading 3,4. For example, a pan-european system with a dozen of operational gateways and a few redundancy gateways would be economically viable: the additional cost of the redundancy gateway is not offset by the benefits of increased system availability. Different design choices to realize diversity are possible 5: this work studies in particular geographical diversity, or (n+p) diversity. This (n+p) diversity scheme provides extremely high availability with very few redundant gateways. However, the impacts on services has still to be evaluated. This paper presents a diversity emulation test-bed developed to experiment different types of gateway handover scenarios to measure their impact on user’s experience. This emulator has been developed by IRT Saint-Exupéry in the framework of the ALBS project (Advanced Link for Broadband Satellite). The emulator is able to simulate both ground network and satellite links, up to the user’s terminals. It is designed to be representative of the network transit and switching losses and delays, as well as the satellite onboard switch behavior. The emulator is used to investigate the influence of the effects that switching mechanisms can have on the ongoing communications. It will also allow to investigate design optimization and provide recommendations to handle these ongoing communication during the gateway handover

    Advanced flight control system study

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    The architecture, requirements, and system elements of an ultrareliable, advanced flight control system are described. The basic criteria are functional reliability of 10 to the minus 10 power/hour of flight and only 6 month scheduled maintenance. A distributed system architecture is described, including a multiplexed communication system, reliable bus controller, the use of skewed sensor arrays, and actuator interfaces. Test bed and flight evaluation program are proposed

    Engine performance characteristics and evaluation of variation in the length of intake plenum

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    In the engine with multipoint fuel injection system using electronically controlled fuel injectors has an intake manifold in which only the air flows and, the fuel is injected into the intake valve. Since the intake manifolds transport mainly air, the supercharging effects of the variable length intake plenum will be different from carbureted engine. Engine tests have been carried out with the aim of constituting a base study to design a new variable length intake manifold plenum. The objective in this research is to study the engine performance characteristics and to evaluate the effects of the variation in the length of intake plenum. The engine test bed used for experimental work consists of a control panel, a hydraulic dynamometer and measurement instruments to measure the parameters of engine performance characteristics. The control panel is being used to perform administrative and management operating system. Besides that, the hydraulic dynamometer was used to measure the power of an engine by using a cell filled with liquid to increase its load. Thus, measurement instrument is provided in this test to measure the as brake torque, brake power, thermal efficiency and specific fuel consumption. The results showed that the variation in the plenum length causes an improvement on the engine performance characteristics especially on the fuel consumption at high load and low engine speeds which are put forward the system using for urban roads. From this experiment, it will show the behavior of engine performance

    Development of economically viable, highly integrated, highly modular SEGIS architecture.

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