This paper proposes a new decentralized control strategy for parallel inverters operating in an islanded Microgrid. The proposed technique uses the Uncertainty and Disturbance Estimation (UDE) strategy in order to gen...
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ISBN:
(纸本)9781479985869
This paper proposes a new decentralized control strategy for parallel inverters operating in an islanded Microgrid. The proposed technique uses the Uncertainty and Disturbance Estimation (UDE) strategy in order to generate a virtual output impedance while keeping the voltage of the internal Elctro-Motive Force (EMF) source equal for all the inverters in the system. The system achieves accurate current sharing over a broad spectrum, which is proportional to the inverter capacity. Simulation results are provided to illustrate the performance of this method.(1)
Actor programming languages provide the kind of inherent parallelism that is needed for building applications in the mobile cloud. This is because the Actor model provides encapsulation (isolation of local state), fai...
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ISBN:
(纸本)9781479959198
Actor programming languages provide the kind of inherent parallelism that is needed for building applications in the mobile cloud. This is because the Actor model provides encapsulation (isolation of local state), fair scheduling, location transparency, and locality of reference. These properties facilitate building secure, scalable concurrent systems. Not surprisingly, very large-scale applications such as Facebook chat service and Twitter have been written in actor languages. The paper introduces the basics of the actor model and gives a high-level overview of the problem of coordination in actor systems. It then describes several novel methods for reasoning about concurrent systems that are both effective and scalable.
Under highly security vulnerable, resource restricted, and dynamically changing mobile ad hoc environments, it is critical to be able to maximize the system lifetime while bounding the communication response time for ...
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ISBN:
(纸本)9781424437511
Under highly security vulnerable, resource restricted, and dynamically changing mobile ad hoc environments, it is critical to be able to maximize the system lifetime while bounding the communication response time for mission-oriented mobile groups. In this paper, we analyze the tradeoff of security versus performance for distributed intrusion detection protocols employed in mobile group communication systems (GCSs). We investigate a distributed voting-based intrusion detection protocol for GCSs in multi-hop mobile ad hoc networks and examine the effect of intrusion detection on system survivability measured by the mean time to security failure (MTTSF) metric and efficiency measured by the communication cost metric. We identify optimal design settings under which the MTTSF metric can be best traded off for the communication cost metric or vice versa.
In this paper we consider the problem of programming for heterogeneous computer systems consist of CPUs and various accelerating devices such as GPUs. We introduce a few of the most popular models for heterogeneous pa...
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ISBN:
(纸本)9781538621622
In this paper we consider the problem of programming for heterogeneous computer systems consist of CPUs and various accelerating devices such as GPUs. We introduce a few of the most popular models for heterogeneous parallel programming, including OpenCL (Open Computing Language), CUDA (Compute Unified Device Architecture), OpenACC, OpenHMPP (Hybrid Multicore parallel Programming), C++ AMP (accelerated massive parallelism), HPL (Heterogeneous Programming Library), etc.
Splitting software into distributed compartments is an important software security technique that limits the effect of vulnerabilities. Unfortunately the resulting systems are difficult to analyze or debug interactive...
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ISBN:
(纸本)9781728174457
Splitting software into distributed compartments is an important software security technique that limits the effect of vulnerabilities. Unfortunately the resulting systems are difficult to analyze or debug interactively when compared to the original. Not only are compartments distributed and executed in parallel, but they may also be strongly isolated by being sandboxed or run in minimal environments that lack debugging facilities. This paper is the first to study practical debugging techniques for strongly-isolated distributed compartments. We adapt ideas from other remote or distributed debugging settings to this domain, and implement and describe two radically different approaches to this problem. We evaluate these approaches both qualitatively and quantitatively, and using both toy examples and real-world open-source software. Our main finding is that out of the two approaches, using GDB remote stubs presents a good balance of performance, flexibility and usability, and we characterize this more precisely in our evaluation.
Future large-scale parallel computer systems, including exascale systems, will operate under an overall power bound. This bound will be enforced by having nodes adhere to local power caps, the sum of which cannot exce...
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ISBN:
(纸本)9781509036820
Future large-scale parallel computer systems, including exascale systems, will operate under an overall power bound. This bound will be enforced by having nodes adhere to local power caps, the sum of which cannot exceed the global power bound. To make efficient use of the available power, protocols have been developed to shift power between nodes, for example to compensate for load imbalance or system noise. The distributed power shifting protocol needs to provide a guarantee of safety that the global power bound will never be exceeded and it needs to have acceptably low overhead under normal operating conditions. We present a variant of the Paxos protocol that guarantees safety. We give an upper bound for the communication overhead of this protocol, along with suggestions for how the overhead can be lowered.
A distributed Lock Manager (DLM) provides advisory locking services to applications such as databases and file systems that run on distributedsystems. Lock management at the server is implemented using First-In-First...
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ISBN:
(纸本)0769523803
A distributed Lock Manager (DLM) provides advisory locking services to applications such as databases and file systems that run on distributedsystems. Lock management at the server is implemented using First-In-First-Out (FIFO) queues. In this paper, we demonstrate a novel way of delegating the lock management to the participating lock-requesting nodes, using advanced network primitives such as Remote Direct Memory Access (RDMA) and Atomic operations. This nicely complements the original idea of DLM, where management of the lock space is distributed. Our implementation achieves better load balancing, reduction in server load and improved throughput over traditional designs.
Multicore systems are increasingly adopted across many application domains. Consequently, understanding their performance is becoming an important issue for a growing number of users. However, performance analysis of ...
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ISBN:
(纸本)9780769546766
Multicore systems are increasingly adopted across many application domains. Consequently, understanding their performance is becoming an important issue for a growing number of users. However, performance analysis of parallel programs on multicore systems is still challenging, especially for large programs or applications developed in multiple programming languages. This paper proposes an analytical modelling approach for studying the parallelism and energy performance of shared-memory programs on multicore systems. The proposed model derives the speedup and speedup loss from data dependency and memory overhead in traditional UMA and NUMA multicore systems, and emerging platforms such as ARM multicores. Using only widely available inputs derived from the trace of the operating system run-queue and hardware events counters, the proposed model achieves high practicality and generality across many types of shared-memory programs running on different multicore platforms. Applications of the model include understanding achieved speedup and parallelism loss, and prediction of optimal core and memory configuration, where the optimality criteria is minimum execution time, minimum energy usage or a trade-off between these two.
Despite the facts that multicore CPUs are present in virtually every personal computer or cell phone and distributedsystems in the form of cloud services are steadily penetrating various domains of our lives, only a ...
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ISBN:
(纸本)9781538655559
Despite the facts that multicore CPUs are present in virtually every personal computer or cell phone and distributedsystems in the form of cloud services are steadily penetrating various domains of our lives, only a minority of programmers and computer science graduates are able to effectively design and develop parallel and distributed applications. Serial thinking is natural to all humans and it is also encouraged by many computer science curricula. Even though that leading educational institutions are attempting to rectify this trend by introducing parallel programming courses into their study programs, these courses are often dedicated for more experienced students in their fourth of fifth year since mastering modern parallel technologies like OpenMP or CUDA requires certain level of programming skills. It can be argued, that the parallel thinking should be taught much sooner, perhaps even before tertiary education. To this end, we have created an educational platform Parapple that aims to introduce parallelism and related problems like load balancing or synchronization to inexperienced programmers in an entertaining form. Our platform is web-based, so it can run in any modern browser on all operating systems without installation and the users are required to have only a very basic understanding of structural imperative programming.
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