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SOLVING ELLIPTIC FINITE ELEMENT SYSTEMS IN NEAR-LINEAR TIME WITH SUPPORT PRECONDITIONERS

SIAM JOURNAL ON NUMERICAL ANALYSIS 2008年第6期46卷 3264-3284页

作者： Boman, Erik G. Hendrickson, Bruce Vavasis, Stephen Univ Waterloo Dept Combinator & Optimizat Waterloo ON N2L 2W2 Canada Sandia Natl Labs Scalable Algorithms Dept Albuquerque NM 87185 USA Sandia Natl Labs Dept Informat & Comp Sci Albuquerque NM 87185 USA

We consider linear systems arising from the use of the finite element method for solving scalar linear elliptic problems. Our main result is that these linear systems, which are symmetric and positive semidefinite, are well approximated by symmetric diagonally dominant matrices. Our framework for de. ning matrix approximation is support theory. Significant graph theoretic work has already been developed in the support framework for preconditioners in the diagonally dominant case, and, in particular, it is known that such systems can be solved with iterative methods in nearly linear time. Thus, our approximation result implies that these graph theoretic techniques can also solve a class of finite element problems in nearly linear time. We show that the support number bounds, which control the number of iterations in the preconditioned iterative solver, depend on mesh quality measures but not on the problem size or shape of the domain.

关键词： finite elements preconditioning matrix algorithm support graph diagonal dominance

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A matrix-based fault section estimation algorithm for complex distribution systems

A matrix-based fault section estimation algorithm for comple...

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42nd International Universities Power Engineering Conference

作者： Mei, Nian Shi, Dongyuan Yang, Zengli Duan, Xianzhong Huazhong Univ Sci & Technol Coll Elect & Elect Engn Wuhan 430074 Hubei Peoples R China

ISBN: (纸本)9781905593361

This paper proposes an application of matrix algorithm to fault section estimation in complex distribution systems based on directed over-current information recorded by FTU (Feeder Terminal Unit). First, a concise unified criterion for fault location in multi-source distribution networks is put forward, which can locate both the multiple faults and the end faults. Considering the communication problems which result in incomplete or distorted FTU over-current information, solutions are given for both situations. When the FTU information is incomplete, the fault section estimation process can be carried on as normal with ignorance of the node whose information is unknown. When the fault information suffers from aberrance, fault section candidates are located first based on the unified criterion tinder no information aberrance. Then the final fault area is selected in terms of the fault information sequence revision cost defined in the paper. The case studies show that the approaches proposed are both correct and feasible, which can effectively resolve the fault location issues in the case of being lack of information or suffering from information aberrance, thus with great potential for application in real-time distribution network fault section estimation programs.

关键词： distribution system matrix algorithm feeder terminal unit fault section estimation

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matrix algorithms for dynamic gain-spectrum adjustment of backward-pumped distributed fiber Raman amplifier

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JOURNAL OF LIGHTWAVE TECHNOLOGY 2006年第3期24卷 1581-1588页

作者： Zhang, W Xiao, L Peng, JD Tsing Hua Univ Dept Elect Engn Beijing 100084 Peoples R China

Two matrix algorithms aiming at a dynamic gain-spectrum adjustment in a backward-pumped distributed fiber Raman amplifier (B-DFRA) are developed based on the relation between changes in the pump power and the gain spectrum. Characteristic channels are chosen to reduce the dimension of matrices in the algorithm, which can be implemented by built-in microprocessors or DSP chips inside the B-DFRA module. Furthermore, as shown by the theoretical analysis and the numerical simulation, elements in the matrices can be directly and easily measured in deployed fiber plants without information on fiber parameters. These matrix algorithms are capable of adjusting the gain spectrum to fit the arbitrary profile desired in reality, while a wide dynamic range can be achieved by a multistage adjustment using matrices measured under several gain levels.

关键词： dynamic gain adjustment dynamic range fiber Raman amplifiers gain spectrum matrix algorithm optical amplifiers optical communication optical fiber amplifiers

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Association mining algorithm based on matrix

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Jisuanji Gongcheng/Computer Engineering 2006年第2期32卷 45-47页

作者： Zeng, Wandan Zhou, Xubo Dai, Bo Chang, Guiran Li, Chunping School of Information Science and Engineering Northeastern Univ. Shenyang 110004 China School of Software Tsinghua Univ. Beijing 100084 China

Apriori algorithm can find out the associations of the data by finding the frequent itemsets by degrees. But it has the performance bottleneck when searching for the high level frequent itemsets. A new algorithm that can directly find the high level frequent itemsets is proposed in this paper. This algorithm can effectively resolve the bottleneck of Apriori. The result of the experiment shows that this algorithm can achieve better performance than Apriori and is more feasible especially when the degree of the frequent itemset is high.

关键词： Apriori algorithm Association mining Frequent itemset matrix algorithm

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Derivation of tropospheric NO₃ profiles using off-axis differential optical absorption spectroscopy measurements during sunrise and comparison with simulations -: art. no. 4168

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JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 2002年第D13期107卷 ACH 5-1-ACH 5-20页

作者： von Friedeburg, C Wagner, T Geyer, A Kaiser, N Vogel, B Vogel, H Platt, U Heidelberg Univ Inst Umweltphys D-69120 Heidelberg Germany Univ Karlsruhe Forschungszentrum Karlsruhe Inst Meteorol & Klimaforsch Karlsruhe Germany

[1] Early morning vertical profiles of tropospheric NO3 were derived by spectroscopy of scattered sunlight in off-axis geometry during sunrise. The measurements were carried out in the urban area of Heidelberg, Germany (April, July, and August 1999). The retrieval algorithm is based on the nitrate radical's rapid photolysis during sunrise, radiative transfer, as well photochemical modeling. We derived NO3 near-ground concentrations of typically (0.2-18) 10(7) cm(-3), concentrations above 3 km of (5-50) 10(7) cm(-3), and a NO3 maximum at a height of 350 m with concentrations of (100900) 10(7) cm(-3). Assuming the case of very high terpene levels even at higher altitudes, which is very unlikely for the atmospheric conditions during the measurements, we obtain a different mathematical solution of our inversion problem yielding the NO3 maximum at altitudes of 2.5 km. The enriched layer was found to hold the bulk of the tropospheric nighttime NO3. The retrieved profile confirms earlier suggestions that ground-level measurements may be significantly underestimating the oxidative capacity of the boundary layer under stable nocturnal conditions. The NO3 layer is probably formed as a result of the vertical profiles of the NO3 educts (NO2 and O-3), with NO2 concentrations falling off more slowly with height than the NO3 scavengers, e. g., anthropogenic NO as well as volatile organic compounds emitted at ground level. Independently from these measurements model simulations with a comprehensive three-dimensional model system were performed for an area, which includes the measurement site. A pronounced maximum (3.3 x 10(9) cm(-3)) of the nocturnal NO3 concentration was found at similar to250 m above the surface, i.e., at the top of the nocturnal stable boundary layer. The average NO3 concentration close to the surface was 5 x 10(7) cm(-3). The only significant difference between the observations and the model results was a steeper decrease of the NO3 concentration above the maxi

关键词： DOAS off axis nitrate radical vertical profile vertical distribution matrix algorithm

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Stepwise assembling of polypeptide chain energy distributions

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COMPUTERS & CHEMISTRY 2001年第2期25卷 145-159页

作者： Jacchieri, SG Fdn Antonio Prudente BR-01509900 Sao Paulo Brazil

The principles and application of conformational analysis software that makes use of a new algorithm are described. It is known that the existence of a local energy minimum in the energy landscape is in general related to the clustering of polypeptide chain conformations near that energy value or, in other words, to a high density of states. A criterion based on this principle is part of an algorithm employed to select subsets of polypeptide chain conformations in broad energy ranges. Chain fragments belonging to these subsets are then combined to build larger polypeptide chains and the corresponding energy distributions. The functionality of the various operations employed in the process is described and the FORTRAN 77 sourer code that defines the algorithm is listed. The methodology is illustrated with a calculation involving three chain fragments belonging to the cellular prion protein (PrPC). (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： conformational analysis density of states potential energy landscape local energy minima matrix algorithm

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Development of a numerical methodology for analysis and design of weldments

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KSME INTERNATIONAL JOURNAL 2001年第4期15卷 422-432页

作者： Sur, U School of Mechanical Engineering Halla University

There are many analysis formulas for determining the resultant shear force in welds. However, there is no general procedure which is applicable to a joint with all six possible loadings exerted simultaneously. A numerical methodology and computer program for such a problem were developed, and they are capable of analyzing a weld of any shape composed of straight or circular line segments. The computer program developed in this study can also display the design procedures and results using computer graphics. The development of such a design procedure and an interactive computer program for weldments analysis will lead to lower cost.

关键词： finite element analysis interactive computer graphics fillet weld moment of inertia shear flow allowable stress matrix algorithm

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運輪網路中邊長改變的最短路徑矩陣算法

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Journal of Industrial and Production Engineering 1998年第3期15卷 299-304页

作者： Huakang Yang[a] [a]Department of Mathematics Yunna University Kunming

摘要摘要本文提出一種運輸網路中邊長改變後尋找各點對間最短路徑的矩陣算法。算法的衩雜性分析表明，運用該算法，計算量確實能少于用現有方法對改變網路重新計算所需耍的計算量。AbstractIn this paper, we propose a matrix algorith... 详细信息

摘要摘要本文提出一種運輸網路中邊長改變後尋找各點對間最短路徑的矩陣算法。算法的衩雜性分析表明，運用該算法，計算量確實能少于用現有方法對改變網路重新計算所需耍的計算量。AbstractIn this paper, we propose a matrix algorithm to determine the shortest paths in a changed network. The analyses indicate that the algorithm takes less computation time than the original algorithms.

关键词：最短路徑 Floy-Warshall算法矩陣算法計算複雜性 shortest paths Floyd-Warsltall-algorithm matrix algorithm computation complexity

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An algorithmic Approach for Solving the Row-by-row Decoupling Problem with Stability

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IFAC Proceedings Volumes 1996年第1期29卷 1217-1222页

作者： Ph. de Larminat J.F. Lafay M. Malabre Laboratoire d'Automatique de Nantes U.R.A.- C.N.R.S. 823. Ecole Centrale de Nantes / Université de Nantes 1 Rue de la Noë 44 072 Nantes Cedex 03 France the G.R. Automatique of the C.N.R.S.

This paper deals with the row-by-row decoupling problem by state feedback for linear square systems. We propose an easily implementable matrix algorithm based on a simple methodology which doesn't need any a priori structural information on the system. Our method goes through the determination of a precompensator (the deconnector) which role is to solve the problems due to the (possible) presence of interconnection infinite and/or finite zeros and to give rise to a precompensated system which is dccouplable by static state feedback with internal stability.

关键词： Linear Control Systems Decoupling matrix algorithm Dynamic Pre-Compensation State Feedback Structural Properties

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A FORTRAN PROGRAM FOR DECONVOLUTION ANALYSIS USING THE matrix algorithm METHOD WITH SPECIAL REFERENCE TO RENOGRAPHY

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COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 1987年第2期24卷 107-116页

作者： KEMPI, V SJUKHUSET DEPT RADIOPHYS S-83183 OSTERSUND SWEDEN

A FORTRAN IV program is presented for deconvolution analysis using the matrix algorithm method. With the deconvolution technique retention functions are calculated from time-activity curve data representing both kidneys and blood background. The program computes for each kidney the minimum and maximum time of the retention function. It also calculates the initial amplitudes, absolute, absolute as well as relative, and the mean transit time of the retention functions. The design of the program allows for optional reviews of intermediate outputs at important stages. It also allows for the plotting of conventional time-activity curves of both kidney corrected for blood background. Finally, the program plots the retention functions and some of their characteristics.

关键词： Deconvolution matrix algorithm Radiopharmaceutical Renography

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