In many implementations of chance constrained programming for engineering design, the required reliability values of the chance constraints are individually specified. Often, this practice is justified, especially whe...
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ISBN:
(纸本)0921303912
In many implementations of chance constrained programming for engineering design, the required reliability values of the chance constraints are individually specified. Often, this practice is justified, especially when the individual constraints represent performance requirements that are of concern independently. However, when reliability should be defined as the probability that the constraints are satisfied as a set, the problem is more complex and difficult to solve. This often happens for environmental problems where each constraint represents a requirement that the concentration of a pollutant meet an ambient standard at a particular geographic location. A meaningful definition of reliability in such cases is the probability that the standard is met at all locations simultaneously, not the probability that it is met at each location taken individually. This paper presents this concept using simple numerical examples and explores options for addressing the problems posed by it. It is shown that analytical methods may be used for right-hand-side variation, as long as the joint distribution of those parameters is known. However, it is recommended that left-hand side variation is best handled only by the MICCP method developed by Morgan et al., and its variants, which rely on Monte Carlo simulation.
The use of System Dynamics Modeling in Supply Chain Management has only recently re-emerged after a lengthy slack period. Current research on System Dynamics Modelling in supply chain management focuses on inventory d...
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The use of System Dynamics Modeling in Supply Chain Management has only recently re-emerged after a lengthy slack period. Current research on System Dynamics Modelling in supply chain management focuses on inventory decision and policy development, time compression, demand amplification, supply chain design and integration, and international supply chain management. The paper first gives an overview of recent research work in these areas, followed by a discussion of research issues that have evolved, and presents a taxonomy of research and development in System Dynamics Modelling in supply chain management.
This paper reviews statistical methods for analyzing output data from computer simulations of single systems. In particular, it focuses on the estimation of steady-state system parameters. The estimation techniques in...
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This paper reviews statistical methods for analyzing output data from computer simulations of single systems. In particular, it focuses on the estimation of steady-state system parameters. The estimation techniques include the replication/deletion approach, the regenerative method, the batch means method, and the standardized time series method.
Complete system simulation to understand the influence of architecture and operating systems on application execution has been identified to be crucial for systems design. While there have been previous attempts at un...
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ISBN:
(纸本)9781581132700
Complete system simulation to understand the influence of architecture and operating systems on application execution has been identified to be crucial for systems design. While there have been previous attempts at understanding the architectural impact of Java programs, there has been no prior work investigating the operating system (kernel) activity during their executions. This problem is particularly interesting in the context of Java since it is not only the application that can invoke kernel services, but so does the underlying Java Virtual Machine (JVM) implementation which runs these programs. Further, the JVM style (JIT compiler or interpreter) and the manner in which the different JVM components (such as the garbage collector and class loader) are exercised, can have a significant impact on the kernel activities. To investigate these issues, this research uses complete system simulation of the SPECjvm98 benchmarks on the SimOS simulation platform. The execution of these benchmarks on both JIT compilers and interpreters is profiled in detail, to identify and quantify where time is spent in each component. The kernel activity of SPECjvm98 applications constitutes up to 17% of the execution time in the large dataset and up to 31% in the small dataset. The average kernel activity in the large dataset is approximately 10%, in comparison to around 2% in four SPECInt benchmarks studied. Of the kernel services, TLB miss handling is the most dominant in all applications. The TLB miss rates in the JIT compiler, dynamic class loader and garbage collector portions of the JVM are individually analyzed. In addition to such execution profiles, the ILP in the user and kernel mode are also quantified. The Java code is seen to limit exploitable parallelism and aggressive instruction issue is seen to be less efficient for SPECjvm98 benchmarks in comparison to SPEC95 programs. Also, the kernel mode of execution does not exhibit as much ILP as the user mode.
We study the problem of compressing massive tables. We devise a novel compression paradigm - training for lossless compression - which assumes that the data exhibit dependencies that can be learned by examining a smal...
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We study the problem of compressing massive tables. We devise a novel compression paradigm - training for lossless compression - which assumes that the data exhibit dependencies that can be learned by examining a small amount of training material. We develop an experimental methodology to test the approach. Our result is a system, pzip, which outperforms gzip by factors of two in compression size and both compression and uncompression time for various tabular data. Pzip is now in production use in an AT&T network traffic data warehouse.
This paper introduces an experimental framework for mobile agents. It utilizes expressiveness and formal foundation of concurrent constraint programming to solve the problem of system support for dynamic rebinding of ...
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ISBN:
(纸本)9781581132069
This paper introduces an experimental framework for mobile agents. It utilizes expressiveness and formal foundation of concurrent constraint programming to solve the problem of system support for dynamic rebinding of not transferable resources and inter-agent collaboration based on logic variables. Proposed solutions help to make the agent-based programming easier and more straightforward and at the same time offer a basis for more sophisticated multi-agent systems.
In this paper, we address the problems of automatically selecting unroll factors for perfectly nested loops, and generating compact code for the selected unroll factors. Compared to past work, the contributions of our...
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ISBN:
(纸本)9781581132700
In this paper, we address the problems of automatically selecting unroll factors for perfectly nested loops, and generating compact code for the selected unroll factors. Compared to past work, the contributions of our work include a) a more detailed cost model that includes ILP and I-cache considerations, b) a new code generation algorithm for unrolling nested loops that generates more compact code (with fewer remainder loops) than the unroll-and-jam transformation, and c) a new algorithm for efficiently enumerating feasible unroll vectors. Our experimental results confirm the wide applicability of our approach by showing a 2.2× speedup on matrix multiply, and an average 1.08× speedup on seven of the SPEC95fp benchmarks (with a 1.2× speedup for two benchmarks). These speedups are significant because the baseline compiler used for comparison is the IBM XL Fortran product compiler which generates high quality code with unrolling and software pipelining of innermost loops enabled. Larger performance improvements due to unrolling of nested loops can be expected on processors that have larger numbers of registers and larger degrees of instruction-level parallelism than the processor used for our measurements (PowerPC 604).
A family F of permutations over U is min-wise independent if for every set S⊂U and every element x∈S, Pr[min{π(S)} = π(x)] = 1/|S| when π is chosen at random from F. The rigorous study of such families was initiat...
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A family F of permutations over U is min-wise independent if for every set S⊂U and every element x∈S, Pr[min{π(S)} = π(x)] = 1/|S| when π is chosen at random from F. The rigorous study of such families was initiated by Broder, Charikar, Frieze, and Mitzenmacher (STOC98), motivated by practical applications such as detecting near duplicate web documents by the AltaVista search engine. For these practical uses, it is required that the family be easily sampleable, and that the permutations be efficiently computable. To achieve this one often uses relaxed notions of min-wise independence, such as Pr[min{π(S)} = π(x)]≥1-Ε/|S| for some small 0<Ε<1. We present a new family of nearly min-wise independent permutations, and argue that the balance it achieves between ease of use and provable statistical properties makes it a favorable candidate for practical applications.
We describe a language-independent and specification-driven program rendering tool that is able to produce high-quality code renderings of arbitrary complexity. The tool can incorporate arbitrary types of information ...
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We describe a language-independent and specification-driven program rendering tool that is able to produce high-quality code renderings of arbitrary complexity. The tool can incorporate arbitrary types of information together with the program code, allowing it to be used for debugging and profiling as well as for producing beautiful renderings of programs for publication. We also present a model for the rendering of programs and apply it to the design of a rendering of Java control flow.
The contributions of this paper are the following. 1. We introduce a new variety of generic programming in which algorithm implementors use a different API than data structure designers, the gap between the API's ...
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ISBN:
(纸本)9781581132700
The contributions of this paper are the following. 1. We introduce a new variety of generic programming in which algorithm implementors use a different API than data structure designers, the gap between the API's being bridged by restructuring compilers. One view of this approach is that it exploits restructuring compiler technology to perform a novel kind of template instantiation. 2. We demonstrate the usefulness of this new generic programming technology by deploying it in a system that generates efficient sparse codes from high-level algorithms and specifications of sparse matrix formats. 3. We argue that sparse matrix formats should be viewed as indexed-sequential access data structures (in the database sense), and show that appropriate abstractions of the index structure of common formats can be conveyed to a restructuring compiler through the type system of a modern language that supports inheritance and templates.
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