In this paper, we propose an equivalence checking method for loop optimizations. those optimizations are effective to improve the performance of both hardware and software. In our proposed method, a symbolic simulatio...
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ISBN:
(纸本)9780889866560
In this paper, we propose an equivalence checking method for loop optimizations. those optimizations are effective to improve the performance of both hardware and software. In our proposed method, a symbolic simulation based method is used to check the equivalence. Before applying symbolic simulation, loops are usually unrolled by certain number of times. this causes two problems. One is that the equivalence of the whole loop executions is not guaranteed if the number of unrolling is not large enough. the other is that the verification time can be very long if the loops are unrolled many times. To solve the problems, we propose the method to verify the equivalence of programs including loops and array accesses without unrolling. In the method, we extract the relations of array indexes and iterators of loops, and find the symbolic values of the iterators, for which the loops need to be executed to compute the output arrays of arbitrary indexes. then, symbolic simulation is applied only to the specified iterations by setting the iterators to particular symbolic values. thus, in most cases, symbolic simulation can complete the task within very small number of iterations. Finally, we show the experimental results on several loop optimizations.
this paper deals withthe computer simulation to obtain an empirical equation for field form factors of a hemispherically capped rod-plane system and determine the range of applicability. To derive a more accurate ana...
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ISBN:
(纸本)9780889866638
this paper deals withthe computer simulation to obtain an empirical equation for field form factors of a hemispherically capped rod-plane system and determine the range of applicability. To derive a more accurate analytical relation for calculating the maximum and average electric fields in rod-plane configuration, the data obtained was analyzed. Good concordance was found between simulated electric filed values and those obtained analytically.
In this paper, we propose an O(n) algorithm that finds a fault-free path between any pair of non-faulty nodes in an n-pancake graph with n - 2 faulty clusters whose diameters are at most 2. the lengths of the paths ob...
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ISBN:
(纸本)9780889867048
In this paper, we propose an O(n) algorithm that finds a fault-free path between any pair of non-faulty nodes in an n-pancake graph with n - 2 faulty clusters whose diameters are at most 2. the lengths of the paths obtained by our algorithm are at most do(Pn) +7 where d o(Pn) = [5(n+1)/3] represents the upper bound of the diameter of Pn given by Gates and Papadimitriou. According to the computer experiment, the average time complexity of the algorithm turned out to be about O(n1.0).
MCell is a Monte Carlo simulator of cell microphysiology, and the scalable variant can be used to study challenging problems of interest to the biological community. MCell can currently model a single synapse out of t...
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Power Line Communication (PLC) systems, which have been around since 1950's but were never thought seriously of as communications method due to low speed, high cost for development, are now gradually spreading to ...
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ISBN:
(纸本)9780889866218
Power Line Communication (PLC) systems, which have been around since 1950's but were never thought seriously of as communications method due to low speed, high cost for development, are now gradually spreading to local area networks and broadband over power line as a realistic and practical means of communications. this is thanks to the technological advances such as new modulation schemes. Based on orthogonal frequency division multiplexing (OFDM) and carrier sense multiple access with collision avoidance (CSMA/CA), the HomePlug 1.0 was developed, and is now the most commonly used technology of power line communications. It supports up to 14 Mbps transmission rate on the power line physical layer. However, just as in 802.11, the throughput performance of this original scheme becomes critical when the number of users increases. In this paper, we propose a constant contention window based medium access control protocol algorithm of HomePlug 1.0 under the assumption that the number of active stations is known. An analytical and simulation framework is used to find the optimal values of contention window size for best performance. We also describe a more realistic node estimation algorithm that each station can implement independently to find the number of contending stations. the modified scheme shows significant enhancement of medium access sublayer performance under saturation conditions.
Previous generation of FPGA devices were neither big enough nor fast enough to allow them to compete with specialized microprocessors. this situation changed in the last five years with FPGA vendors offering devices w...
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ISBN:
(纸本)9780889866218
Previous generation of FPGA devices were neither big enough nor fast enough to allow them to compete with specialized microprocessors. this situation changed in the last five years with FPGA vendors offering devices with more than 5 million gates and running at clock frequencies higher than 400 MHz. these high density FPGAs can now be used to implement custom digital systems (System-On-Chip - SoC), including systems with single and multiple processors (Multiprocessor-Systems-On-Chip - MpSoC) or a combination of both. Taking advantage of the fast development of FPGA devices, academic researchers and industrial R&D groups started using them as a mean to speed up real time simulation of power systems. Here we present a digital real time power system simulator ("DRTPSS") which is solely based on FPGA devices. though the methodology was initially developed for power system simulation, it has broader application as we demonstrated in [7].
Withthe rapid development of electronic commerce, digital signature is very important in preventing from forging, tampering, and disavowing electronic contract in web-based negotiation support system (WNSS). Based on...
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ISBN:
(纸本)9780387754659
Withthe rapid development of electronic commerce, digital signature is very important in preventing from forging, tampering, and disavowing electronic contract in web-based negotiation support system (WNSS). Based on the requirements of electronic contract in WNSS and several techniques widely used in digital signatures, a digital signature scheme for electronic contracts is presented in the paper. Public key algorithm, hash function and interceders are used in the scheme. the feasibility and implementation of the scheme in WNSS are discussed.
the availability of three-dimensional tools for simulation and management of geometric uncertainties in CAD systems bear a strategic importance for the reduction in the number of physical prototypes and for the decrea...
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ISBN:
(纸本)9780889866638
the availability of three-dimensional tools for simulation and management of geometric uncertainties in CAD systems bear a strategic importance for the reduction in the number of physical prototypes and for the decrease in time to market. However, in spite of a growing interest for the various approaches which were proposed in this domain and in spite of the progress of CAD techniques, there are still no genuine computer aided tolerancing tools, in which the designer can have confidence. In reality, the current computer aided tolerancing tools are very limited and based on simplifying assumptions, which do not allow appreciating the validity of the results. To circumvent these problems, a novel tolerancing assistance methodology is proposed. this new approach takes into account all types of uncertainties and is intended to guide and assist the designer in making the most appropriate decision. In fact, it allows the designer to validate the manufacturing processes which can meet the applied tolerances, and even to choose the process leading to an optimal cost. thus, as a result, the reality is reproduced at best, time and money are saved, specifications are respected, errors are reduced, assembly is guaranteed and operation is assured.
Being able to vary the level of detail or scale when modeling any system has an increasing interest in different domains. Here we address the issue of multiscale modeling of transport networks in order to enhance feas...
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ISBN:
(纸本)9780889866638
Being able to vary the level of detail or scale when modeling any system has an increasing interest in different domains. Here we address the issue of multiscale modeling of transport networks in order to enhance feasibility of hybrid simulations, like those who couple macro and micro traffic behaviours, or those who recently tried to combine cellular automata with multi-agent systems in urban simulation and geosimulations. Using an example, we show how a generic link/node representation which forms the core of a design pattern, can be used to instantiate several network models at different scales. Each one can be simulated using the appropriate behavioural model. the design pattern approach avoids drawbacks of strictly hierarchical representations and maintains coherency. We use a multilevel spatial grid to locate vertices that form a link. this hierarchical grid is also a way to deal with behavioural models based on cellular automata. the concept of Place is introduced in order to be able to connect generated synthetic populations to the transport network and, then, to model the travel demand. Multimodality is allowed and opportunities of modal transfers are explicitly defined. the paper also shows how we are using real GIS data of Quebec City to build a three-scale transport network withthe suggested approach.
It has been shown that runtime estimation errors have a large impact on scheduler performance. In previous research, scheduling algorithms were mainly used in a homogeneous environment. In this paper, we investigate s...
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ISBN:
(纸本)9780889867048
It has been shown that runtime estimation errors have a large impact on scheduler performance. In previous research, scheduling algorithms were mainly used in a homogeneous environment. In this paper, we investigate several scheduling heuristics that are commonly used in the grid environment. We systematically study how runtime relative estimation errors affect the scheduler performance in different grid scenarios by conducting experiments using simulation. We choose Dynamic-selection, Min-min, Seg-min-min, Max-min, and Sufferage as our scheduling algorithms for the experiments. Our results show interesting trends: (1) increased estimation error results in degrading performance of all tested scheduling heuristics, making them even worse than the basic "Round-Robin" approach if errors are large;however, locally, performance is sometimes better and, in some special cases, estimation errors do not affect scheduler performance;(2) unlike in general, increased estimation errors diminish the performance difference among individual heuristics;(3) there is a performance threshold, no matter how large the estimation errors are;(4) increased accuracy of runtime estimation improves performance in general.
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