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274 results on '"Ma, Ziwei"'

76. Amphotericin B Tamed by Salicylic Acid

Author

Yu, Yuming, primary, Chen, Peng, additional, Gao, Ming, additional, Lan, Wei, additional, Sun, Shijun, additional, Ma, Ziwei, additional, Sultani, Rome, additional, Cui, Yincang, additional, Umar, Muhammad Naveed, additional, Khan, Sher Wali, additional, Cai, Xiaodong, additional, Liang, Zhenjiang, additional, and Tan, Hui, additional

Published
2022
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80. Synthesis and White-Light Emission of ZnO/HfO2: Eu Nanocables

Author

Liu Lixin, Zhang Hongliang, Wang Yuan, Su Yurong, Ma Ziwei, Xie Yizhu, Zhao Haiting, Chen Changcheng, Liu Yanxia, Guo Xiaosong, Su Qing, and Xie Erqing

Subjects
ZnO, HfO2:Eu, Nanocables, White-light emission, Electrospinning, Materials of engineering and construction. Mechanics of materials, TA401-492
Abstract

Abstract ZnO/HfO2:Eu nanocables were prepared by radio frequency sputtering with electrospun ZnO nanofibers as cores. The well-crystallized ZnO/HfO2:Eu nanocables showed a uniform intact core–shell structure, which consisted of a hexagonal ZnO core and a monoclinic HfO2 shell. The photoluminescence properties of the samples were characterized. A white-light band emission consisted of blue, green, and red emissions was observed in the nanocables. The blue and green emissions can be attributed to the zinc vacancy and oxygen vacancy defects in ZnO/HfO2:Eu nanocables, and the yellow–red emissions are derived from the inner 4f-shell transitions of corresponding Eu3+ ions in HfO2:Eu shells. Enhanced white-light emission was observed in the nanocables. The enhancement of the emission is ascribed to the structural changes after coaxial synthesis.

Published
2010
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83. Inferences on location parameter in multivariate skew-normal family with unknown scale parameter.

Author

Ma, Ziwei, Chen, Ying-Ju, Wang, Tonghui, and Liu, Jing

Subjects
*CONFIDENCE regions (Mathematics), *CONFIDENCE intervals, *INFERENTIAL statistics, *TRAFFIC accidents, *TRANSPORTATION departments, *ORDER statistics
Abstract

In this paper, the statistical inference on the location parameter vector is studied in the multivariate skew-normal model with unknown scale parameter and known shape parameter. Based on the distribution of the generalized Hotelling's T2 statistic, confidence regions and hypothesis tests on the location parameter, μ , are obtained. The power function of the test is studied numerically as well. For illustration the effectiveness and applicability of our purposed methods, the traffic accident data from the National Highway Traffic Safety Administration (NHTSA) in U.S. Department of Transportation are analyzed. [ABSTRACT FROM AUTHOR]

Published
2022
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88. Localization of 3-D Near-field Sources Based on the Joint Phase Interferometer and MUSIC Algorithm

Author

Ma Ziwei, Wenxian Yu, Di He, and Xin Chen

Subjects
Computational complexity theory, Computer science, Phase (waves), 020206 networking & telecommunications, Near and far field, 02 engineering and technology, Phase detector, Azimuth, Interferometry, Circular buffer, 0202 electrical engineering, electronic engineering, information engineering, 020201 artificial intelligence & image processing, Antenna (radio), Algorithm
Abstract

Based on the joint phase interferometer and multiple signal classification (MUSIC) algorithm, two high-performance 3-dimensional (3-D) parameters estimation and localization algorithms for near field sources (NFS) are proposed in this study employing the uniform circular array (UCA). Firstly, the algebraic relation is demonstrated between the azimuth angle under the far-field assumption and the actual near-field source. Using the relation, we estimate the far-field azimuth angle using the 2-dimensional (2-D) MUSIC method and then obtain the estimation result of the azimuth angle for NFS. Secondly, we select two groups of antenna pairs whose distances are less than half of the wavelength, which are called short baselines in the interferometer method. Using a phase detector, the phase differences of the two baselines are measured, which have no phase ambiguity. Then it can estimate the elevation angle and range depending on the algebraic relations between the elevation angle, range and phase differences. The foregoing short-baseline method is qualified to localize a NF source. In addition, in order to get better performance, we propose a long-baseline method with further research. Two groups of antenna pairs whose distances are greater than half of the wavelength are selected as two long baselines. By solving the phase ambiguity, the elevation angle and range can finally be estimated with high precision. The simulation results illustrate that the proposed algorithms can achieve higher localization accuracy than the conventional 3-D MUSIC method. Moreover, the long-baseline method performs better than the short-baseline method. And it is also presented that the computational complexity of the proposed methods can be reduced owing to the fact that the 3-D spectrum peak searching process in the conventional method is not required any more.

Published
2020

90. A Portable Railway Signal Cable Fault Detector

Author

Ma Ziwei and Wei Xue-ye

Subjects
Signal processing, business.industry, Computer science, Detector, Electrical engineering, ComputerApplications_COMPUTERSINOTHERSYSTEMS, Hardware_PERFORMANCEANDRELIABILITY, Fault (power engineering), Signal, Fault detection and isolation, business, Signal conditioning, Railway signal, Digital signal processing
Abstract

Railway signal cables are the infrastructure of railway operations. Signal cable fault detection is one of the important guarantees for the safe operation of railways. The rapid investigation and maintenance of railway signal cable faults are of great significance to the safe operation of trains. This article uses time domain reflectometry (TDR) and signal processing technology to design a portable railway signal cable fault detector, it can quickly and conveniently detect open circuit and short-circuit faults of railway cables on site, and can locate fault points. The detector uses DSP as the main control chip, equipped with signal conditioning circuit, signal processing circuit and so on. Experiments have been carried out in the laboratory to verify that the detector can realize fault detection and location functions.

Published
2020

100. Analysis, Design and Realization of Metadata Managing System for Multimedia Resources

Author

Wu, Xu, Ma, Ziwei, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Chen, Zhaoneng, editor, Chen, Hsinchun, editor, Miao, Qihao, editor, Fu, Yuxi, editor, Fox, Edward, editor, and Lim, Ee-peng, editor

Published
2005
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