LetBbe a set ofnbblue points and R a set of nrred points in the plane, where nb+ nr= n. A blue point b and a red point r can be matched if r dominates b, that is, if x(b) ≤ x(r) and y( b) ≤ y(r). We consider the pro...
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LetBbe a set ofnbblue points and R a set of nrred points in the plane, where nb+ nr= n. A blue point b and a red point r can be matched if r dominates b, that is, if x(b) ≤ x(r) and y( b) ≤ y(r). We consider the problem of finding a maximum cardinality matching between the points in B and the points in R. We give an adaptive parallel algorithm to solve this problem that runs in O(log2n) time using the CREW PRAM with O(n2+∊/log n) processors for some ∊,0 < ∊ < *** follows that finding the minimum number of colors to color a trapezoid graph can be solved within these resource bounds
In this paper, we take initial steps toward developing energy-efficient broadcast algorithms for ad hoc wireless networks that operate under changing connectivity conditions. Such algorithms need to be distributed. An...
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The Broadcast Incremental Power (BIP) algorithm is a centralized heuristic for the construction of energy-efficient broadcast trees in wireless networks. In this paper, we discuss the issues associated with the develo...
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Dynamic programming is an important combinatorial optimization technique that has been widely used in various fields such as control theory, operations research, computational biology and computer science. Many author...
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Dynamic programming is an important combinatorial optimization technique that has been widely used in various fields such as control theory, operations research, computational biology and computer science. Many authors have described parallel dynamic programming algorithms for the family of multistage problems. More scarce is the literature for the more general class of problems where dependences appear between non-consecutive stages. Among the important problems falling in this class is the RNA base pairing problem. In this study we propose a new parallel scheme for a large class of recurrences with triangular iteration space and nonuniform dependences that includes the RNA base pairing problem. We derive two different instances of this scheme that correspond to an horizontal and a vertical traverse of the iteration domain. We develop and extend the tiling approach for this particular class. We formulate and analytically solve the optimization problem determining the tile size that minimizes the total execution time of the tiled program on a distributed memory parallel machine. Our analyze is based on the BSP model, which assures the portability of the obtained results. The computational experiments carried out on the CRAY T3E behave according to the predictions of our theoretical model.
The utilization of multiple DSP systems for parallel processing in computationally demanding applications is growing fast. The field of 2-D imaging and multidimensional signal processing is a good candidate for parall...
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One approach to transformation based compression is the Matching Pursuit Projection (MPP). MPP or variants of it have been suggested for designing image compression and video compression algorithms and have been among...
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ISBN:
(纸本)0819444146
One approach to transformation based compression is the Matching Pursuit Projection (MPP). MPP or variants of it have been suggested for designing image compression and video compression algorithms and have been among the top performing submissions within the MPEG-4 standardization process. In the case of still image coding, the MPP approach has to be paid with an enormous computational complexity. In this work we discuss sequential, as well as parallel speedup techniques of a MPP image coder which is competitive in terms of rate-distortion performance.
Viterbi algorithm is an optimal convolutional decoding algorithm with superpolynomial time complexity. Basic principles of Viterbi algorithm are shown in Figures 1, 2, and 3. In order to improve the algorithm throughp...
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Viterbi algorithm is an optimal convolutional decoding algorithm with superpolynomial time complexity. Basic principles of Viterbi algorithm are shown in Figures 1, 2, and 3. In order to improve the algorithm throughput, one has to apply parallelism. This can be done at different levels, e.g., bit, word, or algorithm level. The paper discusses various approaches to the parallelisation of the decoding algorithm, some implemented in VLSI processing elements, and the other implemented by multiprocessor systems with general purpose processors. A Viterbi decoder basically consists of three main functional blocks shown in Figure 4. Branch Metrics block BM calculates in each time step all branch weights. Add-Compare-Select ACS unit calculates sums of weights and selects optimal survivor paths. Survivor Memory SM analyses partial results from BM and ACS and outputs decoded data within a time delay D. Note that data dependent loop is present in the ACS unit that limits the speed of the decoding procedure because actual branch weight has to be added to the accumulated weights of the survivor path at each time step. Performances of the Viterbi decoder can be improved on bit level by breaking the data dependant loop using carry-save addition and pipelining (see Figure 5). Further, several ACS units can be used in parallel on the word level. Finally, more independent decoders may work on different blocks of input data. After decoding procedure the final result can be obtained by the multiplexing of decoded segments. The mentioned principles can be implemented either in VLSI components connected into a ring topology or by several independent general purpose or DSP processors (see Figures 6 and 7). Theoretical speedup attainable by parallel processing is estimated to be S = pN M / E, where pN represents the number of processors, E the length of the decoded block and M &le E the length of the uniquely decoded data in a block. Considering the performance of contemporary processing e
Task scheduling determines the performance of NOW computing to a large extent. However, the computer system architecture, computing capability and system load are rarely proposed together. In this paper, a biggest het...
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Task scheduling determines the performance of NOW computing to a large extent. However, the computer system architecture, computing capability and system load are rarely proposed together. In this paper, a biggest heterogeneous scheduling algorithm is presented. It fully considers the system characteristics (from application view), structure and state. So it always can utilize all processing resource under a reasonable premise. The results of experiment show the algorithm can significantly shorten the response time of jobs.
Connected dominating set (CDs) has been proposed as virtual backbone or spine of wireless ad hoc networks. Three distributed approximation algorithms have been proposed in the literature for minimum CDS. We first rein...
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algorithms for 2D wavelet transform decomposition on clusters of workstations are described and analyzed. For the parallel algorithm employed, the computation of the transform is structured so that the exchange of int...
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algorithms for 2D wavelet transform decomposition on clusters of workstations are described and analyzed. For the parallel algorithm employed, the computation of the transform is structured so that the exchange of intermediate transform coefficients is restricted only to neighboring processors and the amount of data communicated is independent of the problem size. Results show that the performance of the parallel implementation improves with increasing data size making the parallel algorithm particularly suitable for applications such as image processing, image coding and computer vision. Timings measured on a Myrinet connected Beowulf cluster agree well with the theoretical analysis and indicate that the implementation is cost optimal.
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