Java is a valuable and emerging alternative for the development of parallel applications, thanks to the availability of several Java message-passing libraries and its full multithreading support. The combination of bo...
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Java is a valuable and emerging alternative for the development of parallel applications, thanks to the availability of several Java message-passing libraries and its full multithreading support. The combination of both shared and distributed memory programming is an interesting option for parallel programming multi-core systems. However, the concerns about Java performance are hindering its adoption in this field, although it is difficult to evaluate accurately its performance due to the lack of standard benchmarks in Java. This paper presents NPB-MPJ, the first extensive implementation of the NAS Parallel Benchmarks (NPB), the standard parallel benchmark suite, for Message-Passing in Java (MPJ) libraries. Together with the design and implementation details of NPB-MPJ, this paper gathers several optimization techniques that can serve as a guide for the development of more efficient Java applications for High Performance Computing (HPC). NPB-MPJ has been used in the performance evaluation of Java against C/Fortran parallel libraries on two representative multi-core clusters. Thus, NPB-MPJ provides an up-to-date snapshot of MPJ performance, whose comparative analysis of current Java and native parallel solutions confirms that MPJ is an alternative for parallel programming multi-core systems.
Pavements usually experience different types of distress due to repeated traffic loads, aggressive environmental conditions, construction materials, soil condition of the underline subgrade, and the method of construc...
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Pavements usually experience different types of distress due to repeated traffic loads, aggressive environmental conditions, construction materials, soil condition of the underline subgrade, and the method of construction. Longitudinal and transverse cracking, potholes, rutting, and bleeding are common examples of such distresses associated with flexible pavements. As time progresses, the severity of these distreaaes increases and consequently, ride quality is adversely affected. Early detection and measurement of the extent of distresses coupled with prompt reactive measures are necessary to keep the pavement function at an acceptable level. Traditional methods for distress detection and measurement are laborious, time consuming, and subject the involved personnel to accidents. In contrast, image measurement methods are effortless, safe, and can be performed in a short time. This research paper performs image processing measurements to estimate areas of a pothole and alligator cracking, and sets a program for plane measurements of an area that experience rutting. The image measurements are compared with the traditional measurements. The results show that image measurements are close to those obtained by using the traditional methods.
The use of Java for parallel programming on clusters relies on the need of efficient communication middleware and high-speed cluster interconnect support. Nevertheless, currently there are no solutions that fully fulf...
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The computation capacity of the workstations in an open laboratory is enough to execute not only the local workload but some distributed computation. Unfortunately, the local workload introduces much uncertainty into ...
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Parallel/distributed programming is a complex task that requires a high degree of expertise to fulfill the expectations of high performance computation. The Master/Worker paradigm is one of the most commonly used beca...
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Despite the availability of video-on-demand (VoD) services in a number of cities around the world, the large-scale deployment of VoD services has not been widely explored due to economic constraints. The high complexi...
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Despite the availability of video-on-demand (VoD) services in a number of cities around the world, the large-scale deployment of VoD services has not been widely explored due to economic constraints. The high complexi...
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Despite the availability of video-on-demand (VoD) services in a number of cities around the world, the large-scale deployment of VoD services has not been widely explored due to economic constraints. The high complexity founded in these systems makes the design process very difficult. This study presents a VoD system design for a highspeed metropolitan network, based on ATM technology, located in Brazil. To accomplish this goal, we have utilized our own simulation-based tool for VoD design called VODSim. This tool allows VoD research on any VoD platform, simulating the complete flow path followed by requests from clients to servers passing through the network infrastructure, allowing the configuration and tuning of multiple system parameters. Using VODSim, we analyse possible VoD architectures for the proposal environment (i.e. Centralized-server, Independent-servers, One-level-proxies and Distributedservers), studying key-parameters that have influence in system design. Experimental results show that Distributed-server architecture is the one that adjusts better to the analyzed infrastructure, improving streaming capacity by 16%, 25% and 28% more than One-level-proxies, Centralized and Independent-servers respectively. Taking in account future growth in VoD system, the Distributed-server even provides an unlimited scalability through new local network incorporation and using P2P techniques.
Bayesian inference comprises of parameter estimation and model selection/comparison. A common approach to solving both of these problems has been to use statistical sampling techniques that are inherently non‐Bayesia...
Bayesian inference comprises of parameter estimation and model selection/comparison. A common approach to solving both of these problems has been to use statistical sampling techniques that are inherently non‐Bayesian. This paper presents new Bayesian sampling method that solves both problems by changing the focus of Bayesian inference to the model selection problem first. In the papers [N. Xiang and P. M. Goggins, J. Acoust. Soc. Am. 110, 1415–1424 (2001); 113, 2685–2697 (2003)], the authors developed a model for the decay times and decay modes of acoustically coupled rooms in terms of measured Schroeder’s decay functions. This paper shows how the Bayesian sampling method can be used to evaluate the ‘‘Bayesian evidence’’ term used in model selection as well as determining the decay times along with error estimates.
This paper applies the methods of Bayesian inference to the estimation of decay times in coupled rooms. Previous papers [N. Xiang and P. M. Goggans, J. Acoust. Soc. Am. 110, 1415–1424 (2001); 113, 2685–2697 (2003)] ...
This paper applies the methods of Bayesian inference to the estimation of decay times in coupled rooms. Previous papers [N. Xiang and P. M. Goggans, J. Acoust. Soc. Am. 110, 1415–1424 (2001); 113, 2685–2697 (2003)] developed a solution method to estimate the decay times and the number of decay modes in terms of measured Schroeder’s decay functions. This paper extends the previous work by using statistical sampling methods to efficiently determine the decay times along with error estimates and evaluate the ‘‘Bayesian evidence’’ term used in determining the number of decay modes. This paper discusses the implemented methods together with the previous work to solve the problem of decay time estimation as well as determining the number of decay modes in acoustically coupled rooms.
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