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Research and industrial application of a novel compound permanent magnet synchronous machine
Cheng-zhi FAN, Ming-xing HUANG, Yun-yue YE
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 471-477.
https://doi.org/10.1631/jzus.A0820789
We propose a novel kind of compound permanent magnet synchronous machine (CPMSM), which is applicable in low-speed and high-torque situations. We first explain the structure of the CPMSM. Based on theoretically deducing the calculation formulae of the CPMSM electromagnetic parameters, we analyze the operating characteristics of the CPMSM, and obtain the power-angle curves and working curves. The no-load magnetic field distribution and the cogging torque are analyzed by applying the finite element method of three-dimensional (3D) magnetic fields, to determine the no-load leakage coefficient and the waveform of the cogging torque. Furthermore, the optimal parameters of the permanent magnet for reducing the cogging torque are determined. An important application target of the CPMSM is in direct-drive pumping units. We have installed and tested a direct-drive pumping unit in an existing oil well. Test results show that the power consumption of the direct-drive pumping unit driven by CPMSM is 61.1% of that of the beam-pumping unit, and that the floor space and weight are only 50% of those of a beam-pumping unit. The noise output does not exceed 58 dB in a range of 1 m around the machine when the machine is 1.5 m from the ground.
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Nonlinear multifunctional sensor signal reconstruction based on least squares support vector machines and total least squares algorithm
Xin LIU, Guo WEI, Jin-wei SUN, Dan LIU
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 497-503.
https://doi.org/10.1631/jzus.A0820282
Least squares support vector machines (LS-SVMs) are modified support vector machines (SVMs) that involve equality constraints and work with a least squares cost function, which simplifies the optimization procedure. In this paper, a novel training algorithm based on total least squares (TLS) for an LS-SVM is presented and applied to multifunctional sensor signal reconstruction. For three different nonlinearities of a multifunctional sensor model, the reconstruction accuracies of input signals are 0.001 36%, 0.031 84% and 0.504 80%, respectively. The experimental results demonstrate the higher reliability and accuracy of the proposed method for multifunctional sensor signal reconstruction than the original LS-SVM training algorithm, and verify the feasibility and stability of the proposed method.
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Regularized canonical correlation analysis with unlabeled data
Xi-chuan ZHOU, Hai-bin SHEN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 504-511.
https://doi.org/10.1631/jzus.A0820221
In standard canonical correlation analysis (CCA), the data from definite datasets are used to estimate their canonical correlation. In real applications, for example in bilingual text retrieval, it may have a great portion of data that we do not know which set it belongs to. This part of data is called unlabeled data, while the rest from definite datasets is called labeled data. We propose a novel method called regularized canonical correlation analysis (RCCA), which makes use of both labeled and unlabeled samples. Specifically, we learn to approximate canonical correlation as if all data were labeled. Then, we describe a generalization of RCCA for the multi-set situation. Experiments on four real world datasets, Yeast, Cloud, Iris, and Haberman, demonstrate that, by incorporating the unlabeled data points, the accuracy of correlation coefficients can be improved by over 30%.
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An efficient hybrid evolutionary optimization algorithm based on PSO and SA for clustering
Taher NIKNAM, Babak AMIRI, Javad OLAMAEI, Ali AREFI
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 512-519.
https://doi.org/10.1631/jzus.A0820196
The K-means algorithm is one of the most popular techniques in clustering. Nevertheless, the performance of the K-means algorithm depends highly on initial cluster centers and converges to local minima. This paper proposes a hybrid evolutionary programming based clustering algorithm, called PSO-SA, by combining particle swarm optimization (PSO) and simulated annealing (SA). The basic idea is to search around the global solution by SA and to increase the information exchange among particles using a mutation operator to escape local optima. Three datasets, Iris, Wisconsin Breast Cancer, and Ripley’s Glass, have been considered to show the effectiveness of the proposed clustering algorithm in providing optimal clusters. The simulation results show that the PSO-SA clustering algorithm not only has a better response but also converges more quickly than the K-means, PSO, and SA algorithms.
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An extended discrete particle swarm optimization algorithm for the dynamic facility layout problem
Hassan REZAZADEH, Mehdi GHAZANFARI, Mohammad SAIDI-MEHRABAD, Seyed JAFAR SADJADI
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 520-529.
https://doi.org/10.1631/jzus.A0820284
We extended an improved version of the discrete particle swarm optimization (DPSO) algorithm proposed by Liao et al.(2007) to solve the dynamic facility layout problem (DFLP). A computational study was performed with the existing heuristic algorithms, including the dynamic programming (DP), genetic algorithm (GA), simulated annealing (SA), hybrid ant system (HAS), hybrid simulated annealing (SA-EG), hybrid genetic algorithms (NLGA and CONGA). The proposed DPSO algorithm, SA, HAS, GA, DP, SA-EG, NLGA, and CONGA obtained the best solutions for 33, 24, 20, 10, 12, 20, 5, and 2 of the 48 problems from (Balakrishnan and Cheng, 2000), respectively. These results show that the DPSO is very effective in dealing with the DFLP. The extended DPSO also has very good computational efficiency when the problem size increases.
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A new method in highway route design: joining circular arcs by a single C-Bézier curve with shape parameter
Hua-hui CAI, Guo-jin WANG
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 562-569.
https://doi.org/10.1631/jzus.A0820267
We constructed a single C-Bézier curve with a shape parameter for G2 joining two circular arcs. It was shown that an S-shaped transition curve, which is able to manage a broader scope about two circle radii than the Bézier curves, has no curvature extrema, while a C-shaped transition curve has a single curvature extremum. Regarding the two kinds of curves, specific algorithms were presented in detail, strict mathematical proofs were given, and the effectiveness of the method was shown by examples. This method has the following three advantages: (1) the pattern is unified; (2) the parameter able to adjust the shape of the transition curve is available; (3) the transition curve is only a single segment, and the algorithm can be formulated as a low order equation to be solved for its positive root. These advantages make the method simple and easy to implement.
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Optimal constrained multi-degree reduction of Bézier curves with explicit expressions based on divide and conquer
Lian ZHOU, Guo-jin WANG
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 577-582.
https://doi.org/10.1631/jzus.A0820290
We decompose the problem of the optimal multi-degree reduction of Bézier curves with corners constraint into two simpler subproblems, namely making high order interpolations at the two endpoints without degree reduction, and doing optimal degree reduction without making high order interpolations at the two endpoints. Further, we convert the second subproblem into multi-degree reduction of Jacobi polynomials. Then, we can easily derive the optimal solution using orthonormality of Jacobi polynomials and the least square method of unequally accurate measurement. This method of ‘divide and conquer’ has several advantages including maintaining high continuity at the two endpoints of the curve, doing multi-degree reduction only once, using explicit approximation expressions, estimating error in advance, low time cost, and high precision. More importantly, it is not only deduced simply and directly, but also can be easily extended to the degree reduction of surfaces. Finally, we present two examples to demonstrate the effectiveness of our algorithm.
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Research progress on Fabry-Perot resonator antenna
Zhen-guo LIU, Zhi-chen GE, Xi-yuan CHEN
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 583-588.
https://doi.org/10.1631/jzus.A0820546
The Fabry-Perot resonator (FPR) antenna has found wide applications in microwave and millimeter waves and recently attracted considerable interest. In this paper, a summary of planar and cylindrical structures, analytic models and research development is presented, and a comparison between these structures and analytic models is made, showing that such analytic models as the FP cavity mode, electromagnetic band gap (EBG) defect mode, transmission line mode, and leaky-wave mode are consistent when applied to analyze this type of resonator antenna. Some interesting topics under recent research, including dual or multi-band, improvement of gain bandwidth, low profile and beam control, are surveyed.
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In-vivo retinal imaging by optical coherence tomography using an RSOD-based phase modulator
Ling WANG, Zhi-hua DING, Guo-hua SHI, Yu-dong ZHANG
Journal of Zhejiang University-SCIENCE A (Applied Physics & Engineering), 2009, 10(4): 607-612.
https://doi.org/10.1631/jzus.A0820126
Fourier-domain rapid scanning optical delay line (RSOD) was introduced for phase modulation and depth scanning in a time-domain optical coherence tomography (TD-OCT) system. Investigation of parameter optimization of RSOD was conducted. Experiments for RSOD characterization at different parameters of the groove pitch, focal length, galvomirror size, etc. were performed. By implementing the optimized RSOD in our established TD-OCT system with a broadband light source centered at 840 nm with 50 nm bandwidth, in vivo retina imaging of a rabbit was presented, demonstrating the feasibility of high-quality TD-OCT imaging using an RSOD-based phase modulator.
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20 articles
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