A large variety of methods based on partial differential equations (PDE) use the interface propagation. For their flexibility these methods are being more and more applied to various problems ranging from physics, flu...
详细信息
A large variety of methods based on partial differential equations (PDE) use the interface propagation. For their flexibility these methods are being more and more applied to various problems ranging from physics, fluid mechanics to control theory and computer vision. The solution of the PDE-based interface evolution is in itself a complex iterative computational task involving a great number of iterations (unknown a priori). Therefore, these applications are very demanding on the hardware and their real-time implementation is still a challenging problem. An efficient implementation could be done by using a specific parallel architecture. This paper proposes an original, entirely parallel algorithm to solve the Eikonal equation. Which is the base of applications using a weighted distance function. This algorithm allows the parallel implementation of active contours methods or continuous watershed on a specific hardware.
We present a tomographic reconstruction algorithm based on a frequential decomposition of the data. We show that the frequential components of the attenuation function to be identified can be reconstructed from the fr...
详细信息
We present a tomographic reconstruction algorithm based on a frequential decomposition of the data. We show that the frequential components of the attenuation function to be identified can be reconstructed from the frequential decomposition of the data. Moreover, downsampling techniques added to the identification of null components and coupled to compression techniques, speed up the reconstruction time up to six compared to the classical FBP. We identify the optimal number of frequential components. We show reconstructions from real data. A parallel implementation of our new algorithm is then proposed and evaluated on two small PC clusters.
As general-purpose parallel computers are increasingly being used to speed up different VLSI applications, the development of parallel algorithms for circuit testing, logic minimization and simulation, HDL-based synth...
详细信息
As general-purpose parallel computers are increasingly being used to speed up different VLSI applications, the development of parallel algorithms for circuit testing, logic minimization and simulation, HDL-based synthesis, etc. is currently a field of increasing research activity. In some of these applications the circuit partitioning problem occurs. That implies dividing a circuit into non-overlapping subcircuits while minimizing the number of cuts after the division and balancing the load associated to each one. Very effective heuristic algorithms have been developed in order to solve this problem, but it is unknown how good the partitions are since the problem is NP-complete. In these cases the use of parallel processing can be very useful. This paper describes a parallel evolutionary algorithm for circuit partitioning, where parallelism improves the solutions found by the corresponding sequential algorithm, which indeed is quite effective compared with other previously proposed procedures.
A study on efficient visualization and real-time interactivity of large-scale scenes is discussed. Introducing parallel processing technology, we present a parallelizable strategy with the pipeline algorithm, realize ...
详细信息
ISBN:
(纸本)0780379292
A study on efficient visualization and real-time interactivity of large-scale scenes is discussed. Introducing parallel processing technology, we present a parallelizable strategy with the pipeline algorithm, realize this parallel algorithm based on shared-memory, and then apply this program to a test site, the Peking Olympic Games planning mixed scenes, including real-time rendering, dynamical texture loading, quick browsing and so on. The results show a running performance and real-time interactivity improvement of DEPS (Digital Earth Prototype System) when using this algorithm. The parallel program of this paper was developed and running on a Silicon Graphics multiprocessor, Onyx 3200, with four MIPS R12000 processors and InfiniteReality 3 graphic accelerator, under IRIX 6.5 operating system.
We present an optimal parallel selection algorithm on the EREW PRAM. This algorithm runs in O(log n) time with n/log n processors. This complexity matches the known lower bound for parallel selection on the EREW PRAM ...
详细信息
ISBN:
(纸本)9780898715385
We present an optimal parallel selection algorithm on the EREW PRAM. This algorithm runs in O(log n) time with n/log n processors. This complexity matches the known lower bound for parallel selection on the EREW PRAM model. We therefore close this problem which has been open for more than a decade.
Existing parallel association rule mining algorithms suffer from many problems when mining massive transactional datasets. One major problem is that most of the parallel algorithms for a shared nothing environment are...
详细信息
Existing parallel association rule mining algorithms suffer from many problems when mining massive transactional datasets. One major problem is that most of the parallel algorithms for a shared nothing environment are Apriori-based algorithms. Apriori-based algorithms are proven to be not scalable due to many reasons, mainly: (1) the repetitive I/O disk scans, (2) the huge computation and communication involved during the candidacy generation. This paper proposes a new disk-based parallel association rule mining algorithm called Inverted Matrix, which achieves its efficiency by applying three new ideas. First, transactional data is converted into a new database layout called Inverted Matrix that prevents multiple scanning of the database during the mining phase, in which finding globally frequent patterns could be achieved in less than a full scan with random access. This data structure is replicated among the parallel nodes. Second, for each frequent item assigned to a parallel node, a relatively small independent tree is built summarizing co-occurrences. Finally, a simple and non-recursive mining process reduces the memory requirements as minimum candidacy generation and counting is needed, and no communication between nodes is required to generate all globally frequent patterns.
We present the first space and time optimal parallel algorithm for the pairwise sequence alignment problem, a fundamental problem in computational biology. This problem can be solved sequentially in O(mn) time and O(m...
详细信息
We present the first space and time optimal parallel algorithm for the pairwise sequence alignment problem, a fundamental problem in computational biology. This problem can be solved sequentially in O(mn) time and O(m+n) space, where m and n are the lengths of the sequences to be aligned. The fastest known parallel space-optimal algorithm for pairwise sequence alignment takes optimal O(m+n/p) space but suboptimal O((m+n) 2 /p) time, where p is the number of processors. On the other hand, the most space economical time-optimal parallel algorithm takes O(mn/p) time but O(m+n/p) space. We close this gap by presenting an algorithm that achieves both time and space optimality, i.e. requires only O(m+n/p) space and O(mn/p) time. We also present an experimental evaluation of the proposed algorithm on an IBMxSeries cluster
In this paper, we devise and implement a parallel protocol reassembling algorithm in application layer for large scale network intruding. Conventional network intrusion detection systems (NIDS) scan the incoming IP pa...
详细信息
ISBN:
(纸本)0780377818
In this paper, we devise and implement a parallel protocol reassembling algorithm in application layer for large scale network intruding. Conventional network intrusion detection systems (NIDS) scan the incoming IP packets and judge the attack types by the sensitive information matching. In our algorithm the IP fragments and the TCP stream are reassembled into an entire datagram in the application layer in parallel which is searched for sensitive field. This increases performance even under hostile loads and enables efficient intrusion detection in high speed networks. A high-performance parallel protocol reassembling algorithm is presented and implemented with SMTP protocol.
作者：
L.FW. GoesC.A.P.S. MartinsElectrical Engineering
Computational and Digita Systems Laboratory Pontifical Catholic University of Minas Gerais Belo Horizonte Minas Gerais Brazil Computer Science Department
Elechical Engineering Computational and Digital System Laboratory Pontifical Catholic University of Minas Gerais Belo Horizonte Minas Gerais Brazil
Turbulent flow has a significantly higher drag than the corresponding laminar flow at the same flow conditions, and therefore incurs a significant penalty of increased fuel consumption due to the extra thrust required...
详细信息
ISBN:
(纸本)0780379241
Turbulent flow has a significantly higher drag than the corresponding laminar flow at the same flow conditions, and therefore incurs a significant penalty of increased fuel consumption due to the extra thrust required. One possible way of decreasing the drag is to apply surface suction to delay the transition from laminar to turbulent flow. In this paper an aerofoil with 3 non-overlapping panels covering up to 20% of chord for boundary layer transition control is considered. The problem is complicated by the fact that panels can change both their positions and lengths. The complexity of the optimization problem is such that it is not practical to perform the investigation using a single processor. A constrained global parallel algorithm based on a combination of deformed configuration methods and controlled random search method is developed. It is shown that for the problem considered, good solutions can be found efficiently.
暂无评论