Gas force has great influence on linear compressor performance and it is normally nonlinear and time varying. To make it easy for the theoretical analysis and control of linear compressor, the gas force is generally r...
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Gas force has great influence on linear compressor performance and it is normally nonlinear and time varying. To make it easy for the theoretical analysis and control of linear compressor, the gas force is generally represented by an equivalent spring and an equivalent damper, thus the linear model of gas force is important to the precision of the theoretical model. However, the existing numerical linearization methods of gas force are lack of experimental validation. To solve this problem, this paper presents a new online measuring method for the gas kinetic parameters based on a vector algorithm, and builds up an online measuring test bench, then experimentally investigates the dynamics characteristics of the gas kinetic parameters and compares the numerical results with the experimental results. The comparisons show that the numerical results using Fourier transform agree well with the experimental results.
a comparative study of performance is conducted between two indoor positioning algorithms described in the Literature, the vector and Ecolocation algorithms. Both use received signal strength (RSS) to implement a radi...
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ISBN:
(纸本)9781509048151
a comparative study of performance is conducted between two indoor positioning algorithms described in the Literature, the vector and Ecolocation algorithms. Both use received signal strength (RSS) to implement a radio frequency fingerprinting technique. The experiment is conducted using commercial ray tracing software called Wireless Insite and Matlab. The vector algorithm performs better than the Ecolocation algorithm, which suffers heavily from an ambiguity issue. For the vector algorithm, the median position error was 2.79 m and 90% of errors were less than 5.72 m
The complete circuit dq transformation of a three phase AC-DC MC, namely matrix rectifier (MR) system, is derived by utilizing circuit dq transformation technique and input current space vector algorithm. Then the mod...
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ISBN:
(纸本)9780780395138
The complete circuit dq transformation of a three phase AC-DC MC, namely matrix rectifier (MR) system, is derived by utilizing circuit dq transformation technique and input current space vector algorithm. Then the model is partially differentially linearized, and the AC small signal circuit model is obtained, so is the state equation of matrix converter system. Based on the system signal-flow chart, the transfer functions of output variables to input variables are derived, then the dynamic behaviors of open loop system is analyzed theoretically. The above theoretical analysis is proved by the simulated results, laying the foundation for further system design. But the case of slightly unbalanced input voltages in practical applications is not considered here.
A new vector algorithm is presented for computing the stiffness matrices of layered reinforced concrete shell elements. Each element stiffness matrix is represented in terms of three vector arrays of lengths 78, 96 an...
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A new vector algorithm is presented for computing the stiffness matrices of layered reinforced concrete shell elements. Each element stiffness matrix is represented in terms of three vector arrays of lengths 78, 96 and 36, respectively. One element stiffness matrix is calculated at a time without interruption in the vector calculations for the uncracked or cracked elements. It is shown that the present algorithm is 1.1 to 7.3 times more efficient then a previous algorithm developed by us on a Gray Y-MP supercomputer.
vector algorithms and the relative importance of the four basic modules (computation of element stiffness matrices, assembly of the global stiffness matrix, solution of the system of linear simultaneous equations, and...
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vector algorithms and the relative importance of the four basic modules (computation of element stiffness matrices, assembly of the global stiffness matrix, solution of the system of linear simultaneous equations, and calculation of stresses and strains) of a finite element computer program for inelastic analysis of reinforced concrete shells are presented. Performance of the vector program is compared with a scalar program. For a cooling tower problem, the speedup factor from the scalar to the vector program is 34 for the element stiffness matrices calculation, 25.3 for the assembly of global stiffness matrix, 27.5 for the equation solver, and 37.8 for stresses, strains and nodal forces computations on a Gray Y-MP. The overall speedup factor is 30.9. When the equation solver alone is vectorized, which is computationally the most intensive part of a finite element program, a speedup factor of only 1.9 is achieved. When the rest of the program is also vectorized, a large additional speedup factor of 15.9 is attained. Therefore, it is very important that all the modules in a nonlinear program are vectorized to gain the full potential of the supercomputers. The vector finite element computer program for inelastic analysis of RC shells with layered elements developed in the present study enabled us to perform mesh convergence studies. The vector program can be used for studying the ultimate behavior of RC shells and used as a design tool.
An important kernel of scientific software is the multiplication of a sparse matrix by a vector. The efficiency of the algorithm on a vector computer depends on the storage scheme. With storage by rows, performances a...
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An important kernel of scientific software is the multiplication of a sparse matrix by a vector. The efficiency of the algorithm on a vector computer depends on the storage scheme. With storage by rows, performances are limited in general by the small vector length. Therefore a storage by so-called generalized columns has been designed, which provides long vectors and consequent good performance. However, it is not suitable for the symmetric case. A new type of storage, by sparse diagonals, has thus been defined. It still exhibits long vectors, with performances as good as previously, but it is also well-suited to symmetric matrices. Results on a CRAY 2, with various sparse matrices, compare the three algorithms and show the efficiency of the storage by sparse diagonals.
The Buneman variant of the block cyclic reduction algorithm begins as a highly parallel algorithm, but collapses with each reduction to a very serial one. Using partial fraction expansions of rational matrix functions...
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The Buneman variant of the block cyclic reduction algorithm begins as a highly parallel algorithm, but collapses with each reduction to a very serial one. Using partial fraction expansions of rational matrix functions, it is shown how to regain the parallelism. The resulting algorithm using $n^2 $ processors runs in $O(\log ^2 n)$ time.
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