An Ordered Binary Decision Diagram (BDD) is a graph representation of a Boolean function. According to its good properties, BDD's are widely used in various applications. In this paper, we investigate the computat...
详细信息
An Ordered Binary Decision Diagram (BDD) is a graph representation of a Boolean function. According to its good properties, BDD's are widely used in various applications. In this paper, we investigate the computational complexity of basic operations on BDD's. We consider two important operations: reduction of a BDD and binary Boolean operations based on BDD's. This paper shows that both the reduction of a BDD and the binary Boolean operations based on BDD's are NC1-reducible to REACHABILITY. That is, both of the problems belong to NC2. In order to extend the results to the BDD's with output inverters, we also considered the transformations between BDD's and BDD's with output inverters. We show that both of the transformations are also NC1-reducible to REACHABILITY.
Three-dimensional (3D) electromagnetic (EM) modeling is an important tool for geophysical applications. In EM induction methods the modified Helmholtz equation is often used to describe scattered or residual electric ...
详细信息
Three-dimensional (3D) electromagnetic (EM) modeling is an important tool for geophysical applications. In EM induction methods the modified Helmholtz equation is often used to describe scattered or residual electric fields in three dimensions. Throughout this paper, a high order compact finite difference scheme for the solution of that equation for vertical magnetic dipole source (VMD) is presented. The approximation of the residual electric field intensity using a fourth order compact finite difference (FD) discretizer is achieved with the solution of a block linear system, the coefficient matrices are large and sparse with a particular structure, implying the application of a matrix-free Krylov subspace method for an efficient numerical solution. The proposed solver is being examined using a number of test problems in uniform and non-uniform grid spacing where numerical and analytical solutions for the homogeneous half-space cases are being compared.
This paper presents a parallel sorting algorithm which sorts n elements in O(n/w + n log n/p) time using p(less-than-or-equal-to n) processors arranged in a 1-dimensional grid with w (less-than-or-equal-to n1-epsilon)...
详细信息
This paper presents a parallel sorting algorithm which sorts n elements in O(n/w + n log n/p) time using p(less-than-or-equal-to n) processors arranged in a 1-dimensional grid with w (less-than-or-equal-to n1-epsilon) buses for every fixed epsilon > 0. Furthermore, it is shown that n X p elements can be sorted in O(n/w + n log n/p) time on p x p (p less-than-or-equal-to n) processors arranged in a 2-dimensional grid with w(less-than-or-equal-to n1-epsilon) buses in each column and in each row. These algorithms are optimal because their time complexities are equal to the lower bounds.
Tato práce se zabývá praktickým využitím technologie OpenCL ve společnosti AVG. AVG vidí OpenCL jako jednu z možností, jak ulehčit zátěž procesoru a případně urychlit v...
详细信息
Tato práce se zabývá praktickým využitím technologie OpenCL ve společnosti AVG. AVG vidí OpenCL jako jednu z možností, jak ulehčit zátěž procesoru a případně urychlit výpočet některých algoritmů. Velká část práce se zabývá optimalizacemi pro grafické karty AMD a NVIDIA, jakožto současné nejrozšířenější karty. Praktická část popisuje paralelizaci dvou algoritmů dodaných AVG, jejich analýzu z pohledu OpenCL a implementaci. Následně jsou popsány a odůvodněny dosažené výsledky a jsou popsány podmínky, pro které má smysl testované paralelní algoritmy použít v reálném produktu. Jako součást implementace je vytvořena knihovna, která usnadňuje práci při vývoji aplikací pracující s OpenCL.
Unstructured grid flow solvers for the compressible Navier-Stokes equations are surveyed. Significant progress are made in the areas of spatial and temporal discretization and adaptative and parallel algorithms. Newly...
详细信息
Unstructured grid flow solvers for the compressible Navier-Stokes equations are surveyed. Significant progress are made in the areas of spatial and temporal discretization and adaptative and parallel algorithms. Newly developed field equation turbulence models seem to mesh nicely with the unstructured grid framework. Based on these developments, it is safe to say that unstructured grid technology is almost on par with structured grid technology, although encumbered with additional memory andcomputational costs.
Aiming at the simulation problem of the super large slotted waveguide array antenna, the parallel higher-order method of moment is used and the coupling effect between each slot element is taken into account to perfor...
详细信息
Aiming at the simulation problem of the super large slotted waveguide array antenna, the parallel higher-order method of moment is used and the coupling effect between each slot element is taken into account to perform the integrated and accurate simulation. In order to ensure that the algorithm is efficient and stable in the parallel process, the BDPLU strategy is introduced to reduce the communication pressure and eliminates the redundant communication of the equation solving when pivoting, which speeds up the process of matrix equation solving. According to different types of waveguide port forms, the computation of rectangular wave port and coaxial wave port is studied, and a new parallel matrix filling technique of wave port is used to accelerate the matrix filling process. Numerical examples calculated at "Tianhe-2" supercomputer show that the algorithm can efficiently and accurately handle the simulation analysis of most types of complex slotted waveguide array.
We present a general algorithm to speed up multiple sequence alignment on modern multi-core computers. This algorithm is implemented in a software called CDAM. By clustering, CDAM partitions a large-scale alignment pr...
详细信息
We present a general algorithm to speed up multiple sequence alignment on modern multi-core computers. This algorithm is implemented in a software called CDAM. By clustering, CDAM partitions a large-scale alignment problem into smaller and more tractable sub-problems, which can be solved by existing alignment algorithms in parallel. The aligned clusters are then merged to form a solution to the original alignment problem. By performance evaluation on an 8-core computer using the classical benchmarks, BAliBASE, PREFAB, IRMBASE, and OXBench, and twenty-eight artificially generated datasets, it is shown that CDAM provides significant performance improvement with reasonable loss of accuracy. In some cases, a gain in accuracy is observed. The CDAM program, source code, and test data are freely available for academic users at http://***/CDAM/.
This paper proposes new real-time heuristic distributed parallel algorithms for search, which are based on the concepts of propagations and competitions of concurrent waves. These algorithms are characterized by simpl...
详细信息
This paper proposes new real-time heuristic distributed parallel algorithms for search, which are based on the concepts of propagations and competitions of concurrent waves. These algorithms are characterized by simplicity and clearness of control strategies for search, and distinguished abilities in many aspects, such as real-time performance, wide suitability for searching AND/OR implicit graphs, and ease in hardware implementation.
For the current state-of-practice in soil-structure interaction (SSI) of nuclear facilities, the strain-dependent characteristics of soil are considered indirectly via equivalent linear methods in the frequency domain...
详细信息
For the current state-of-practice in soil-structure interaction (SSI) of nuclear facilities, the strain-dependent characteristics of soil are considered indirectly via equivalent linear methods in the frequency domain, typically represented by the SASSI program. SSI analysis in the time-domain, although directly involving material nonlinearity of the soil, is inefficient in practice up to now. Based on Partitioned Analysis of SSI (PASSI), a method for nonlinear soil-structure interaction analysis is developed in this paper, by applying implicit time-step integration and explicit one with different time steps to nuclear island and to soil, respectively. The incremental equilibrium equation and explicit decoupling method are used to analyze the soil nonlinearity described by the Davidenkov model with simplified loading-reloading rules, which avoids solving algebraic equations and iteration processes. An asynchronous parallel algorithm for nonlinear SSI analysis is given. A simple example is given to verify the partitioned approach with explicit-implicit co-computation against the full-explicit approach. Seismic response characteristics of nuclear power plants are investigated by comparing responses of nonlinear analysis with linear analysis. Different results address the importance of nonlinear SSI analysis for the seismic performance of nuclear structures.
Community detection has arisen as one of the most relevant topics in the field of graph data mining due to its applications in many fields such as biology, social networks, or network traffic analysis. Although the ex...
详细信息
Community detection has arisen as one of the most relevant topics in the field of graph data mining due to its applications in many fields such as biology, social networks, or network traffic analysis. Although the existing metrics used to quantify the quality of a community work well in general, under some circumstances, they fail at correctly capturing such notion. The main reason is that these metrics consider the internal community edges as a set, but ignore how these actually connect the vertices of the community. We propose the Weighted Community Clustering (WCC), which is a new community metric that takes the triangle instead of the edge as the minimal structural motif indicating the presence of a strong relation in a graph. We theoretically analyse WCC in depth and formally prove, by means of a set of properties, that the maximization of WCC guarantees communities with cohesion and structure. In addition, we propose Scalable Community Detection (SCD), a community detection algorithm based on WCC, which is designed to be fast and scalable on SMP machines, showing experimentally that WCC correctly captures the concept of community in social networks using real datasets. Finally, using ground-truth data, we show that SCD provides better quality than the best disjoint community detection algorithms of the state of the art while performing faster.
暂无评论