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IEEE international symposium on Intelligent Control (ISIC)

作者： H. Boussalis C. Liu K. Rad J. Dong S. Fallorina P. Thienphrapa J. Roberts Department of Electrical and Computer Engineering California State University Hayward Los Angeles CA USA Structures Pointing and Control Engineering Laboratory California State University Hayward Los Angeles CA USA

Control of complex, flexible structures requires substantial amounts of computational power to achieve precision performance in both space and time. This is due to the fact that such structures are inherently multiple input, multiple output systems whose complexities increase significantly with each additional input or output parameter. The other design difficulty is due to the requirement of realtime computation and data communication since such systems have to be controlled on the fly. Thus, general purpose computer architectures are simply insufficient in this scenario. This paper introduces the development of an embedded computing system that supports the implementation of control algorithms on a segmented reflector telescope testbed. Decentralized algorithms have been recognized and proven to provide promising performance of control, and are being used for primary mirror shaping and precision pointing control of this testbed. The system architecture of the testbed is featured with a suite of interconnected signal processors and high performance I/O devices to meet the computational requirements, and hence, allows real-time performance of the control algorithms. The system also supports fault-tolerance during processor failure or recovery by leveraging the technologies of decentralized control with its associative pipelined task mapping mechanism

关键词： parallel algorithms distributed control Computer architecture Control systems Signal processing algorithms Communication system control System testing Shape control Flexible structures Data communication

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A study of throughput degradation following single node failure in a data sharing system

A study of throughput degradation following single node fail...

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international symposium on Fault-Tolerant Computing (FTCS)

作者： N.S. Bowen A. Roy-Chowdhury IBM Thomas J. Watson Research Center Hawthorne NY USA University of Illinois Urbana IL USA

The data sharing approach to building distributed database systems is becoming more common because of its potentially higher processing power and flexibility compared to data partitioning. However, due to the large amounts of hardware and complex software involved, the likelihood of a single node failure in the system increases. Following a single node failure, some processing has to be done to determine the set of locks held by transactions which were executing at the failed node. These locks cannot be released until database recovery has completed on the failed node. This phenomenon can cause throughput degradation even if the processing power on the surviving nodes is adequate to handle all incoming transactions. This paper studies the throughput dropoff behavior following a single node failure in a data sharing system through simulations and analytical modeling. The analytical model reveals several important factors affecting post-failure behavior and is shown to match simulations quite accurately. The effect of hot locks (locks which are frequently accessed) on post-failure behavior is observed. Simulations are performed to observe system behavior after the set of locks held by transactions on the failed node has been determined and show that if the delay in obtaining this information is too large, the system is prone to thrashing.< >

关键词： Throughput Degradation Transaction databases Database systems Internet Analytical models Power system modeling Availability Hardware Failure analysis

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Limits of Control Flow on parallelism

Limits of Control Flow on Parallelism

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Annual international symposium on Computer Architecture, ISCA

作者： M.S. Lam R.P. Wilson Computer Systems Laboratory University of Stanford CA USA

This paper discusses three techniques useful in relaxing the constraints imposed by control flow on parallelism: control dependence analysis, executing multiple flows of control simultaneously, and speculative execution. We evaluate these techniques by using trace simulations to find the limits of parallelism for machines that employ different combinations of these techniques. We have three major results. First, local regions of code have limited parallelism, and control dependence analysis is useful in extracting global parallelism from different parts of a program. Second, a superscalar processor is fundamentally limited because it cannot execute independent regions of code concurrently. Higher performance can be obtained with machines, such as multiprocessors and dataflow machines, that can simultaneously follow multiple flows of control. Finally, without speculative execution to allow instructions to execute be- fore their control dependences are resolved, only modest amounts of parallelism can be obtained for programs with complex control flow.

关键词： parallel processing Permission Upper bound Concurrent computing Laboratories Computational modeling distributed computing Machinery Hardware Prediction algorithms

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X-type interface for management of multi-domain, multi-technology networks

X-type interface for management of multi-domain, multi-techn...

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IFIP/IEEE international symposium on Integrated Network Management

作者： R. Diaz-Caldera J. Serrat-Fernandez K. Berdekas F. Karayannis Department Signal Theory and Comms Campus Nord-UPC MòdulD4 Universitat Poliltècnica de Catalunya Barcelona Spain Universitat Politecnica de Catalunya Barcelona Catalunya ES Department Electrical Eng and Computer Science National and Technical University of Athens Athens Greece

The specification and implementation of Xcoop interfaces has received great attention in the last few years. In fact, the appropriate design of this system component is a key aspect for efficient and seamless co-operative management. In this context it is worth mentioning the EURESCOM P408 project and the standards of the European Telecommunication Standards Institute (ETSI) in Europe and the ITU-T and Telemanagement Forum related work worldwide. The Xcoop specification presented in this paper, produced as part of the results of the project MISA co-funded by the Commission of the European Union, is a step ahead in the evolution of this system interface. Distinguished from preceding works, this one allows interactions between management systems independently to the underlying network technology, ATM, SDH or hybrid. This is achieved by defining appropriate functionality and an information model, indeed, where the specific characteristics of ATM and SDH resources are abstracted and merged in common classes.

关键词： Synchronous digital hierarchy Telecommunication standards Object oriented modeling Europe databases Testing Computer network management Computer science Technology management Resource management

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Super abacus: a Beowulf class parallel computer for multimedia signal processing research

Super abacus: a Beowulf class parallel computer for multimed...

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international symposium on Intelligent Multimedia, Video and Speech Processing

作者： Lai-Man Po Chun-Ho Cheung Ka-Man Wong CityU Image Processing Laboratory Department of Electronic Engineering City University of Hong Kong Hong Kong China

ISBN: (纸本)9628576623

A few thousands years ago, Chinese people used small rods connected to movable counters such as beads to construct a low-cost calculation device, which is called Abacus. Today, Beowulf-class parallel computer using such similar approach to construct a low-cost supercomputing system, in which Pentium-based computers (beads) are connected by a Fast Ethernet switch (rods) to form a parallel supercomputer. This paper presents our experiences learnt from the construction of a 17-node Beowulf-class cluster called Super Abacus. The system is designed to provide high computational power for handling real-time multimedia signal processing such as audio/video compression, multimedia database searching and content-based audio/video classification so as to support multimedia signal processing research projects in CityU Image Processing Laboratory. The technologies and methodologies to achieve the goal of lower system cost with better performance will be described.

关键词： Concurrent computing Multimedia databases Switches Multimedia systems Video signal processing Video compression Counting circuits Ethernet networks Supercomputers Signal design

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parallel real-time simulation on commodity hardware with reusable power system models 21

Parallel real-time simulation on commodity hardware with reu...

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proceedings of the 2021 IEEE/ACM 25th international symposium on distributed Simulation and Real Time Applications

作者： Raphael Eidenbenz Carsten Franke Mats Larsson Alexandru Moga Thanikesavan Sivanthi Hitachi ABB Power Grids Research Switzerland Munich University of Applied Sciences Germany Hitachi ABB Power Grids Switzerland ABB Corporate Research Switzerland

ISBN: (纸本)9781665433266

This paper proposes a real-time power system simulation framework that is capable of simulating steady state and electromechanical transients of power systems, with sub-millisecond time resolution. The framework can integrate power system component models packed as reusable Functional Mockup Units (FMUs) to flexibly create power system simulations without the need to recreate new models for different power systems. The integration of individual components is based on a novel model decomposition method, which enables the FMU reuse in different system contexts, as well as a parallel simulation execution onto multi-core machines. Furthermore, the paper proposes methods to optimize the allocation of components to cores and shows that the framework can simulate a medium voltage distributed electrical grid of about 20 components in real-time on a commodity multi-core machine.

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Implementation of SAR interferometric map generation using parallel processors

Implementation of SAR interferometric map generation using p...

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IEEE international symposium on Geoscience and Remote Sensing (IGARSS)

作者： N. Doren D.E. Wahl Systems Assessment and Research Center Sandia National Laboratories Albuquerque NM USA

Interferometric fringe maps are generated by accurately registering a pair of complex SAR images of the same scene imaged from two very similar geometries, and calculating the phase difference between the two images by averaging over a neighborhood of pixels at each spatial location. The phase difference (fringe) map resulting from this IFSAR operation is then unwrapped and used to calculate the height estimate of the imaged terrain. Although the method used to calculate interferometric fringe maps is well known, it is generally executed in a post-processing mode well after the image pairs have been collected. In that mode of operation, there is little concern about algorithm speed and the method is normally implemented on a single processor machine. This paper describes how the interferometric map generation is implemented on a distributed-memory parallel processing machine. This particular implementation is designed to operate on a 16 node Power-PC platform and to generate interferometric maps in near real-time. The implementation is able to accommodate large translational offsets, along with a slight amount of rotation which may exist between the interferometric pair of images. If the number of pixels in the IFSAR image is large enough, the implementation accomplishes nearly linear speed-up times with the addition of processors.

关键词： Pixel Layout Geometry Laboratories Synthetic aperture radar interferometry Phase estimation parallel processing Reflectivity Azimuth Postal services

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Towards a Fog-to-Cloud control topology for QoS-aware end-to-end communication

Towards a Fog-to-Cloud control topology for QoS-aware end-to...

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international Workshop on Quality of Service

作者： Vitor Barbosa Souza Alejandro Gómez Xavi Masip-Bruin Eva Marín-Tordera Jordi Garcia Advanced Network Architectures Lab (CRAAX) Universitat Politècnica de Catalunya (UPC) Spain Informatics Department (DPI) Universidade Federal de Viçosa (UFV) Brazil

ISBN: (纸本)9781538627051

The recent deployment of novel network concepts, such as M2M communication or IoT, has undoubtedly stimulated the placement of a new set of services, leveraging both centralized resources in Cloud Data Centers and distributed resources shared by devices at the edge of the network. Moreover, Fog Computing has been recently proposed having as one of its main assets the reduction of service response time, further enabling the deployment of real-time services. Albeit QoS-aware network researches have been originally focused on data plane issues, the successful deployment of real-time services, demanding very low delay on the allocation of distributed resources, depends on the assessment of the impact of controlling decisions on QoS. Recently, Fog-to-Cloud (F2C) computing has been proposed as a hierarchical layered-architecture relying on a coordinated and distributed management of both Fog and Cloud resources, enabling the distributed and parallel allocation of resources at distinct layers, thus suitably mapping services demands into resources availability. In this paper, we assess the layered management architecture in F2C systems, taking into account its distributed nature. Preliminary results show the tradeoff observed regarding controllers capacity, number of controllers, and number of controller layers in the F2C architecture.

关键词： Delays Quality of service databases Topology Cloud computing Process control Computer architecture

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Safe caching in a distributed file system for network attached storage

Proceedings of the International Parallel Processing Symposi...

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proceedings of the international parallel Processing symposium, IPPS 2000年 155-162页

作者： Burns, Randal C. Rees, Robert M. Long, Darell D.E. IBM Almaden Research Cent San Jose United States

In a distributed file system built on network attached storage, client computers access data directly from shared storage, rather than submitting I/O requests through a server. Without a server marshaling access to data, if a computer fails or becomes isolated in a network partition while holding locks on cached data objects, those objects become inaccessible to other computers until a locking authority can guarantee that the lock holder will not again directly access these data. We describe a server that acts as the locking authority and implements a lease-based protocol for revoking access to data objects locked by an isolated or failed computer. When a lease expires, the server can be assured that the client no longer acts on locked data, and can safely redistribute locks to other clients. During normal operation, this protocol invokes no message overhead, and uses no memory and performs no computation at the locking authority.

关键词： Client server computer systems

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Improving the processing of decision support queries: the case for a DSS optimizer

Improving the processing of decision support queries: the ca...

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international symposium on Database Engineering and Applications (IDEAS)

作者： H. Schwarz R. Wagner B. Mitschang Institute of Parallel and Distributed High-Performance Systems University of Stuttgart Stuttgart Germany

ISBN: (纸本)0769511406

Many decision support applications are built upon data mining and OLAP tools and allow users to answer information requests based on a data warehouse that is managed by a powerful DBMS. We focus on tools that generate sequences of SQL statements in order to produce the requested information. Our thorough analysis revealed that many sequences of queries that are generated by commercial tools are not very efficient. An optimized system architecture is suggested for these applications. The main component is a DSS optimizer that accepts previously generated sequences of queries and remodels them according to a set of optimization strategies, before they are executed by the underlying database system. The advantages of this extended architecture are discussed and a couple of appropriate optimization strategies are identified. Experimental results are given, showing that these strategies are appropriate to optimize query sequences of OLAP applications.

关键词： Computer aided software engineering Decision support systems Data mining Data warehouses Database systems Data analysis Architecture Energy management Power system management Association rules

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