Hybrid technical systems combine discrete-state event-driven and continuous-state time-driven behaviour. In this contribution, a general modeling formalism for such systems is proposed. the discrete subsystem is repre...
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Hybrid technical systems combine discrete-state event-driven and continuous-state time-driven behaviour. In this contribution, a general modeling formalism for such systems is proposed. the discrete subsystem is represented by an interpreted Petri net. In addition to external continuous inputs, discrete variables dependent on the net marking affect the continuous subsystem which is a time-driven state space model. Limit violations of particular continuous state variables as well as external binary inputs are interpreted as events and change the discrete state of the system. In view of the analysis of hybrid technical systems reachability and stability are defined. the modeling method is applied to a mixing tank.
A considerable number of language mechanisms have been proposed during recent years, to specify and implement concurrent object-oriented programs. the major concern of these proposals is to design an expressive langua...
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A considerable number of language mechanisms have been proposed during recent years, to specify and implement concurrent object-oriented programs. the major concern of these proposals is to design an expressive language that provides extensible concurrent processing and synchronization features. Almost all these efforts, however, have focused on the multiple-client-single-server model where each server determines its synchronization semantics without cooperating with other objects. We believe that object-oriented concurrent languages must not only support a single-server model, but cooperatively synchronizing servers as well. We refer to this as multi-server synchronization. We first classify multi-server synchronization into five categories. the intention is to define a framework for evaluating current approaches and identifying the requirements for designing new languages. In addition, we present a composable multi-server synchronization technique, adopting the concept of composition-filters.
We present the Data parallel Fortran (DPF) benchmark suite, a set of data parallel Fortran codes for evaluating data parallel compilers appropriate for any target parallel architecture, with shared or distributed memo...
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We present the Data parallel Fortran (DPF) benchmark suite, a set of data parallel Fortran codes for evaluating data parallel compilers appropriate for any target parallel architecture, with shared or distributed memory. the codes are provided in basic, optimized and several library versions. the functionality of the benchmarks cover collective communication functions, scientific software library functions, and application kernels that reflect the computational structure and communication patterns in fluid dynamic simulations, fundamental physics and molecular studies in chemistry or biology. the DPF benchmark suite assumes the language model of High Performance Fortran, and provides performance evaluation metrics of busy and elapsed times and FLOP rates, FLOP count, memory usage, communication patterns, focal memory access, and arithmetic efficiency as well as operation and communication counts per iteration. An instance of the benchmark suite was fully implemented in CM-Fortran and tested on the CM-5.
Traditionally, the Navy has developed systems which distribute time-sensitive data using specialized components such as dedicated point-to-point communications links. Today, however the Navy is moving away from specia...
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Traditionally, the Navy has developed systems which distribute time-sensitive data using specialized components such as dedicated point-to-point communications links. Today, however the Navy is moving away from specialized solutions and toward Commercial-Off-the-Shelf (COTS) components to both keep up withthe rapid pace of technology changes and to reduce system costs. COTS components are designed to meet needs of applications in the general commercial marketplace, not the specialized needs of real-time applications. this paper examines the ability of COTS workstations to distribute and process time sensitive data in a shared media environment. Several metrics are defined and then used to evaluate the performance of a simulated time sensitive data distribution and processing mechanism running on COTS workstations from Hewlett Packard, the Digital Equipment Corporation, and Sun Microsystems. the data collected is analyzed. COTS real-time operating system features are then used to tune the performance of the client and server components of the mechanism.
the most important goal in hard real-time systems is to guarantee that all timing constraints are satisfied. Even though object-based techniques (which contain reusable software components) are used to manage the comp...
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the most important goal in hard real-time systems is to guarantee that all timing constraints are satisfied. Even though object-based techniques (which contain reusable software components) are used to manage the complexity in the software development process of such systems, execution efficiency may have to be sacrificed, due to the large number of procedure calls and contention for accessing software components. these issues are addressed by the following parallelizing techniques: converting potentially inefficient procedure calls to a source of concurrency via asynchronous remote procedure calls (ARPC); and replicating (or cloning) software components to reduce the contention. the existing object-based scheduling algorithms construct an initial schedule and apply incremental parallelization techniques to modify the initial schedule until a feasible schedule is generated. these algorithms are applicable for scheduling only multiple independent tasks. this paper describes a pre-run-time scheduling algorithm for a set of periodic object-based tasks having precedence constraints among them. the algorithm employs parallelism exploitation techniques to guarantee timeliness in almost fully predictable environments such as factory automation, aerospace, and avionics. It allocates the components of object-based periodic tasks to the sites of a distributed system based on a clustering heuristic which takes into account the ARPC parallelism and load balancing, and schedules them on respective sites.
the proceedings contains 67 papers. Topics discussed include multimedia systems, parallel processing systems, distributed and parallel programming, metacomputing track, user interfaces, broadband networks, computer wo...
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the proceedings contains 67 papers. Topics discussed include multimedia systems, parallel processing systems, distributed and parallel programming, metacomputing track, user interfaces, broadband networks, computer workstations, computer programming language and algorithms, quality of service, distributed shared memory, network protocols, input/output systems and data storage, wide area distribution systems, asynchronous transfer mode networks.
We discuss here the emergent Web based distributed environments for HPCC on the NII withthe focus on Java as an enabling technology. We start with a review of the past, presence and the near term future of the 'J...
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ISBN:
(纸本)0818675829
We discuss here the emergent Web based distributed environments for HPCC on the NII withthe focus on Java as an enabling technology. We start with a review of the past, presence and the near term future of the 'Java phenomenon', exposed here in the background of some related previous approaches towards a distributed interpretative virtual machine architecture.
the rise of explicit parallel programming involves new problems: lack of structure for parallel algorithms and the ad hoc development of parallel algorithms. We use skeletons to characterize and design parallel algori...
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ISBN:
(纸本)0818675829
the rise of explicit parallel programming involves new problems: lack of structure for parallel algorithms and the ad hoc development of parallel algorithms. We use skeletons to characterize and design parallel algorithms and define a process to refine the designs step-by-step into programs. this paper introduces a high-level library on top of MPI which is derived from the skeleton concept to achieve better programmability and obtain portability. We conclude with a CFD application to demonstrate our idea.
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