Parallel and distributed computing infrastructure are increasingly being embraced in the context of manufacturing applications, including real-time scheduling. In this paper, we present the design and implementation o...
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Parallel and distributed computing infrastructure are increasingly being embraced in the context of manufacturing applications, including real-time scheduling. In this paper, we present the design and implementation of one such framework that can work on the Internet, with applications in manufacturing. The architecture, aliased as DPAC (Distributed and Parallel Computing framework), has the goal of harnessing the Internet's vast, growing computational capacity for ultra-large, coarse-grained parallel applications. The idea is to bring together diverse, heterogeneous, geographically distributed computing environments in order to attack large-scale computing problems. We present a scalable and fault-tolerant architecture in DPAC and the results of running performance experiments. DPAC is implemented on the interoperable, increasingly secure, and ubiquitous platform, viz, Java. The unique feature of DPAC is that it frees application developers from concerns about complex interprocess communication and fault tolerance among Internet-worked hosts and supports piecework and branch-and-bound computational models. We describe an implementation and present case studies showing the effectiveness in solving complex combinatorial optimization problems in the context of manufacturing systems.
A set of unsteady 3D Navier-Stokes simulations was used to investigate the effects of end-wall shape and first-stage vane stacking on the performance of a two-stage supersonic turbine. Restacking of the vanes was succ...
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A set of unsteady 3D Navier-Stokes simulations was used to investigate the effects of end-wall shape and first-stage vane stacking on the performance of a two-stage supersonic turbine. Restacking of the vanes was successfully used to eliminate a large separated/secondary flow region at the hub between the first-stage vanes and rotors. Altering the shape of the end wall in the first stage had little effect on the separated flow region. There was a significant performance increase obtained at the design flow conditions by reducing the separated flow region. It is anticipated that the benefits of improving the behavior of the flow near the end wall will be even greater at off-design operating conditions. (CSA)
Computing power and molecular simulation methodology have improved dramatically over the past decade, and for some systems molecular models are reaching a point where they can provide information that approaches or su...
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Computing power and molecular simulation methodology have improved dramatically over the past decade, and for some systems molecular models are reaching a point where they can provide information that approaches or surpasses the quality of real experimental data. Molecular simulation can also be a potent tool for developing qualitative understanding, and this feature suggests widespread use of molecular simulation as a tool for teaching. Broader use of molecular simulation for these purposes requires tools that promote understanding and application of simulation software. We present an "object-oriented" view of molecular simulation that can help conceptualize and organize its elements, and discuss software development tools that we have constructed that enable non-experts in simulation or graphical programming to create instructive molecular simulations. We finish with an example of one such simulation applet, which we have used in the classroom. Tools described here are available on the web at ***/etomica. (C) 2002 Elsevier Science B.V. All rights reserved.
Computing power and molecular simulation methodology have improved dramatically over the past decade, and for some systems molecular models are reaching a point where they can provide information that approaches or su...
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Computing power and molecular simulation methodology have improved dramatically over the past decade, and for some systems molecular models are reaching a point where they can provide information that approaches or surpasses the quality of real experimental data. Molecular simulation can also be a potent tool for developing qualitative understanding, and this feature suggests widespread use of molecular simulation as a tool for teaching. Broader use of molecular simulation for these purposes requires tools that promote understanding and application of simulation software. We present an "object-oriented" view of molecular simulation that can help conceptualize and organize its elements, and discuss software development tools that we have constructed that enable non-experts in simulation or graphical programming to create instructive molecular simulations. We finish with an example of one such simulation applet, which we have used in the classroom. Tools described here are available on the web at ***/etomica. (C) 2002 Elsevier Science B.V. All rights reserved.
Workflow is an important class of applications in the daily business. A number of web-based workflow systems have been developed recently as a natural extension to traditional workflow systems to exploit the growing p...
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Workflow is an important class of applications in the daily business. A number of web-based workflow systems have been developed recently as a natural extension to traditional workflow systems to exploit the growing popularity of the Internet. However, most of them are designed based on the specific application at hand. In this paper, we distill out the fundamental elements of a workflow system into a general workflow framework. The framework provides appropriate application programming interfaces for programmers to fill in the application specific requirements of a workflow system at hand. This is realized through two object-wrappers: the Task interface and the Resource interface, which support the specification of the tasks involved in the workflow schedule and the resources accessed respectively. A major characteristic of the framework is that the particular workflow schedule under execution is fluid, in the sense that the tasks involved as well as their precedence relationships can be modified dynamically. Consistency constraints will be examined in this paper which determine when such modifications are allowed. To maximize flexibility, we adhere our design to the CORBA architecture, which has been becoming highly popular in recent years, thus allowing tasks and resources of different types to interoperate in our framework. We demonstrate the feasibility of our framework with a small prototype that allows tasks in a workflow system to be scheduled and executed.
The future Internet is expected to support applications with quality of service (QoS) requirements. For this end several mechanisms are suggested in the IETF to support signaling, one of the most promising among them ...
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ISBN:
(纸本)0769513816
The future Internet is expected to support applications with quality of service (QoS) requirements. For this end several mechanisms are suggested in the IETF to support signaling, one of the most promising among them is IntServ. In this paper, we study the relationship between the QoS implementing mechanism and application demands, and make a set of an improved applicationinterface beyond the stand RSVP API. Our goal is to provide an API friendly to applications, through extracting the key elements from the traffic parameters and reservation parameters which should be opaque to applications.
The architecture, interface, and functionality of the Windows application programming interface (API) make it difficult to master and use effectively, and contribute negatively to the safety, robustness, and portabili...
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The architecture, interface, and functionality of the Windows application programming interface (API) make it difficult to master and use effectively, and contribute negatively to the safety, robustness, and portability of the applications developed under it. The API is structured around a large and constantly evolving set of functions and is based on a problematic shared library implementation. The provided interfaces are complicated, nonorthogonal, abuse the type system, cause name-space pollution, and use inconsistent naming conventions. In addition, the functionality of the interface suffers from inconsistency, incompleteness, and inadequate documentation. application developers, programming tool vendors, and Microsoft should face the above problems and provide appropriate solutions. (C) 1998 Elsevier Science B.V. All rights reserved.
This paper presents the results of a low cost, PC-DSP based motion control system development. The Texas Instruments TMS320C31 floating point Digital Signal Processor is selected for the real-time hardware platform wh...
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ISBN:
(纸本)0819429791
This paper presents the results of a low cost, PC-DSP based motion control system development. The Texas Instruments TMS320C31 floating point Digital Signal Processor is selected for the real-time hardware platform while code development and user interface tasks reside on a standard, non real-time PC platform such as the Pentium/Windows 95 systems. An application programming interface (API) has been implemented to facilitate open architecture code development. Finally, application to the control of an Adept linear robotic workcell is made with 2 input shaper designs serving as the test algorithms.
Since the late 80s there are a growing need of the machine tool builders and the end users to have open architecture controllers. Different levels of openness can be defined analyzing the available research results an...
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Since the late 80s there are a growing need of the machine tool builders and the end users to have open architecture controllers. Different levels of openness can be defined analyzing the available research results and products. The main initiatives leading the current research in these efforts are the European OSACA, the American OMAC and the OSEC from Japan. A complex comparison of these projects and their goals and achievements is presented in this paper. It is stated that in their present form it is not possible to merge easily the three results to get a unified and potentially worldwide accepted open architecture controller.
For more than a decade NEC dominated the Japanese PC market with its PC-98 architecture, which was incompatible both with its major Japanese rivals and the global PC standard. However, NEC was powerless to prevent the...
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For more than a decade NEC dominated the Japanese PC market with its PC-98 architecture, which was incompatible both with its major Japanese rivals and the global PC standard. However, NEC was powerless to prevent the introduction of Japanese versions of Windows 3.1 and 95 that ran on its competitors' architectures as well as on the PC-98, unifying the Japanese PC market and creating a common set of application programming interfaces for all Intel-based Japanese PCs. The introduction of Windows rendered obsolete the large DOS-based software library that had provided strong positive externalities for the NEC architecture. Absent those advantages, the market share of the PC-98 standard fell from 60% to 33% in five years, and NEC finally abandoned the PC-98 in favor of the global standard. An examination of the unusual rise and fall of the PC-98 shows how victory in a standards competition can be negated by the introduction of a new architectural layer that spans two or more previously incompatible architectures.
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