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970 results about "Sparse matrix" patented technology

In numerical analysis and scientific computing, a sparse matrix or sparse array is a matrix in which most of the elements are zero. By contrast, if most of the elements are nonzero, then the matrix is considered dense. The number of zero-valued elements divided by the total number of elements (e.g., m × n for an m × n matrix) is called the sparsity of the matrix (which is equal to 1 minus the density of the matrix). Using those definitions, a matrix will be sparse when its sparsity is greater than 0.5.

Graph-based semi-supervised high-spectral remote sensing image classification method

The invention relates to a graph-based semi-supervised high-spectral remote sensing image classification method. The method comprises the following steps: extracting the features of an input image; randomly sampling M points from an unlabeled sample, constructing a set S with L marked points, constructing a set R with the rest of the points; calculating K adjacent points of the points in the sets S and R in the set S by use of a class probability distance; constructing two sparse matrixes WSS and WSR by a linear representation method; using label propagation to obtain a label function F<*><S>, and calculating the label prediction function F<*><R> of the sample points in the set R to determine the labels of all the pixel points of the input image. According to the method, the adjacent points of the sample points can be calculated by use of the class probability distance, and the accurate classification of high-spectral images can be achieved by utilizing semi-supervised conduction, thus the calculation complexity is greatly reduced; in addition, the problem that the graph-based semi-supervised learning algorithm can not be used for large-scale data processing is solved, and the calculation efficiency can be improved by at least 20-50 times within the per unit time when the method provided by the invention is used, and the visual effects of the classified result graphs are good.
Owner:XIDIAN UNIV

Multiattribute collaborative filtering recommendation method oriented to social network

The invention discloses a multiattribute collaborative filtering recommendation method oriented to a social network. The multiattribute collaborative filtering recommendation method includes utilizing mass data information of the social network to collect user, friend and item list information, and establishing an original user-item scoring matrix; utilizing a thought of acquiring a middle average value from nine numbers, and performing prediction filling on a sparse matrix; calculating inter-user attracting similarity through a user-item bipartite graph; calculating interaction similarity, linearly combining the attracting similarity with the interaction similarity to acquire comprehensive similarity among users, and searching to acquire a nearest neighbor set of a target user; performing prediction scoring on items to be recommended by the target user according to the nearest neighbor set of the target user, and generating a Top-N recommendation set. By the method, calculating rules of inter-user similarity in a conventional collaborative filtering method are improved, huge impedance brought to the filtering recommendation method and a recommendation system by sparseness of a scoring matrix is reduced, and accuracy of the recommendation system is improved.
Owner:CHONGQING UNIV OF POSTS & TELECOMM

Method for increasing computing speed through parallel computing based on MPI and OpenMP hybrid programming model

The invention discloses a method for increasing the computing speed through parallel computing based on an MPI and OpenMP hybrid programming model. The method includes the steps that the callable MPI process number and OpenMP thread number are determined according to the computing node number and the available CPU core number in nodes; an existing sub sparse matrix A, the sub initial vector x0, the block vector b and the maximum computing tolerance Tolerance are read into each process; a multi-thread compiling command is enabled for each process; cycle computing of a precondition conjugate gradient method is conducted on all the processes; if the computed error is smaller than the permissible value, cycle computing is ended, and otherwise, cycle computing is continuously conducted; computing results of all the processes are reduced, and a solution of a problem is output; when parallel computing is conducted, MPI processes are started, multi-thread resolving is conducted on the problem, parallel computing among the nodes is started, all the MPI processes are distributed to one computing node, and information is exchanged through message transmission among the processes; then in all the MPT processes, an OpenMP guidance command is used to create a set of threads, and the threads are distributed to different processors of the computing node to be executed.
Owner:INST OF SOFTWARE APPL TECH GUANGZHOU & CHINESE ACAD OF SCI

Method and apparatus for efficient training of support vector machines

The present invention provides a system and method for building fast and efficient support vector classifiers for large data classification problems which is useful for classifying pages from the World Wide Web and other problems with sparse matrices and large numbers of documents. The method takes advantage of the least squares nature of such problems, employs exact line search in its iterative process and makes use of a conjugate gradient method appropriate to the problem. In one embodiment a support vector classifier useful for classifying a plurality of documents, including textual documents, is built by selecting a plurality of training documents, each training document having suitable numeric attributes which are associated with a training document vector, then initializing a classifier weight vector and a classifier intercept for a classifier boundary, the classifier boundary separating at least two document classes, then determining which training document vectors are suitable support vectors, and then re-computing the classifier weight vector and the classifier intercept for the classifier boundary using the suitable support vectors together with an iteratively reindexed least squares method and a conjugate gradient method with a stopping criterion.
Owner:R2 SOLUTIONS

Fast decoupled flow calculation method for power systems

The invention discloses a fast decoupled flow calculation method for power systems, which comprises the following steps of: inputting original data and initializing voltage; forming an admittance matrix; forming correction equation coefficient matrixes B' and B'' and performing factor table decomposition; performing P-theta iteration, and correcting a voltage phase angle; performing Q-V iteration, and correcting voltage amplitude; judging whether the iteration is converged; and calculating node power and branch power. The method requires that the P-theta iteration and the Q-V iteration are all converged in the same iteration and the iteration process is finished, so that the algorithm frame is simpler, and the flow is clearer. The sparse matrix technology is not adopted, so the matrix elements are convenient to access and calculate, and the programming is simple; the correction equation coefficient matrixes are stored according to n order, number change of nodes is avoided, and the programming difficulty is reduced; and the calculation amount is reduced through reasonable logic judgment, the calculation speed is obviously improved and the requirement of scientific research can be completely met. The fast decoupled flow calculation method also can process power systems with a plurality of balance nodes.
Owner:DALIAN MARITIME UNIVERSITY

Low-rank expression and learning dictionary-based hyperspectral image abnormity detection algorithm

The invention belongs to the technical field of remote sensing image processing, and specifically relates to a low-rank expression and learning dictionary-based hyperspectral image abnormity detection algorithm. According to the algorithm, a method for introducing low-rank expression in the abnormity detection problems is used for decomposing the two-dimensional hyperspectral image data into the sum of a low-rank matrix expressing background and a sparse matrix expressing abnormity, and then enabling a basic abnormity detection algorithm to act on the sparse matrix to obtain the abnormity detection result; and furthermore, the concept of a learning dictionary is imported in the low-rank expression algorithm, and the learning dictionary is obtained through an algorithm of random selection and gradient descent and is capable of expressing the background spectrums in hyperspectral images. Through the importing of the learning dictionary, the abnormity information can be better separated from the hyperspectral image data, so that better detection result can be obtained; and meanwhile, the robustness of the algorithm for the initial parameters can be improved, so that the computing cost is reduced and important value is provided for the actual abnormity detection application.
Owner:FUDAN UNIV

Distributed source center direction-of-arrival estimation method based on Bayesian compressed perception

The invention provides a distributed source center direction-of-arrival estimation method based on Bayesian compressed perception, and belongs to the technical field of wireless mobile communication. The invention mainly aims to solve the problem concerning inherent error of center direction-of-arrival estimation when the center angle of arrival of an information source is not on an angle sampling grid. According to the invention, an antenna array composed of parallel uniform linear arrays is arranged; an approximate array data reception model of a distribution source is established; the space-domain angle is sampled; a parameterized over-complete redundant dictionary is constructed by using an array steering vector so as to make the problem of distributed source center direction-of-arrival estimation converted into the problem of sparse matrix equation solving; a Bayesian compressed perception method is adopted to solve the equation set and obtain the most sparse solution of an unknown sparse vector; and the estimated value of the center direction of arrival is obtained according to the one-to-one correspondence relationship between sparse solutions and space-domain angles. The method of the invention is low in computing complexity, and has the characteristics of high resolution and accuracy under the condition of a small number of snapshots.
Owner:UNIV OF ELECTRONICS SCI & TECH OF CHINA

High-efficiency time domain electromagnetic simulation method based on H matrix algorithm

The invention discloses a high-efficiency time domain electromagnetic simulation method based on an H matrix algorithm, which can realize electromagnetic simulation on a large three-dimensional target. In the method, a time domain finite element method (TDFEM) is used as a background, a low-rank compression technique is used as a core, and a tree structure is used as a basis for carrying out logical unit (LU) decomposition on a sparse matrix generated by the TDFEM by a four arithmetic algorithm corresponding to the H matrix. The acquired upper and lower triangular factors have low-rank compressible characteristics, and the compressed matrix equation can realize quick solution of high-efficiency time domain electromagnetic simulation by the H matrix algorithm. The high-efficiency time domain electromagnetic simulation method has the advantages of fast computation speed, low memory consumption, controllable computation accuracy, good stability and the like, can reduce the complexity of computation to O(Nlog<2>N) and reduce the memory consumption to O(NlogN), can be widely applied to the solution of a large sparse linear system of equations during high-efficiency time domain electromagnetic simulation, and can provide important reference for analyzing the electromagnetic property of the large three-dimensional target.
Owner:NANJING UNIV OF SCI & TECH

Vibration modeling and analyzing method of crack impeller structure of centrifugal compressor

The invention discloses a vibration modeling and analyzing method of a crack impeller structure of a centrifugal compressor. The vibration modeling and analyzing method comprises the steps of firstly, providing a modeling method of a centrifugal impeller, obtaining a whole model by rotating and converting a finite element model of a section of the impeller, reducing the DOF (Degree of Freedom) of a system by adopting a hybrid interface modal synthesis method, and simulating a breath effect of a crack by defining a contact mode on a crack interface; secondly, providing a method for solving large-scale symmetrical sparse matrix-inverse matrix, and thus obviously reducing the memory space needed by calculation; finally, providing a method for carrying out statistical analysis on resonant frequency of the crack impeller structure, considering dissonant factors such as manufacturing error and state degradation which exist in an actual impeller, and obtaining statistical regularity of structure resonant frequency under a random dissonant mode. According to the vibration modeling and analyzing method disclosed by the invention, the calculating accuracy is ensured, obvious improvement effect of calculating efficiency is realized at the same time, and a high-efficiency analyzing method is provided for optimal design of the impeller and quantitative diagnosis of the crack.
Owner:XI AN JIAOTONG UNIV

Encoder of LDPC code of layered quasi-circulation extended structure

The present invention discloses a coder of LDPC code used in hierarchical quasi-cyclic expansion structure, comprising an input cache, a first depositing and caching pipeline grade, a second depositing pipeline grade, a third caching pipeline grade, a fourth depositing and caching pipeline grade and an output grade. By utilizing the character that the check matrix H is formed by connecting the quasi-cyclic sift matrix, the present invention simplifies the pipeline structure of the RU coding method, reduces the grades of the pipeline from sixth grade to fourth grade, and shortens the coding delay. Besides, the present invention decreases the largest pipeline delay and increases the coding thuoughput according to the fulfilling character of the main functional module. And the present invention also reduces the energy consumption of the coder ROM according to the operational character of the quasi-cyclic sift matrix; replaces the sparse matrixmultiply vector in the RU method with the quasi-cyclic sift unit matrix multiply vector; and replaces the non sparse matrix multiply vector in the RU method with the quasi-cyclic sift matrix multiply vector. A larger storing space can be remained in the ping pong RAM amid the grades to fit the demand of the variable length code and the VBR.
Owner:SHANGHAI JIAO TONG UNIV
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