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A new family of windows——convolution windows and their applications

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science China(Technological sciences) 2005年第4期48卷 468-480页

作者： ZHANG Jieqiu1,2. LIANG Changhong1 & CHEN Yanpu3 1. Department of Applied Math. & Phys., College of science, Airforce Engineering University, Xi’an 710051, China 2. National key {2. of Antennas and Microwave Technology, Xidian University, Xi’an 710071, China 3. Computer Center, Xi’an Communication College, Xi’an 710106, China 1. Department of Applied Math. & Phys. College of Science Airforce Engineering University 710051 Xi’an China 2. National key laboratory of Antennas and Microwave Technology Xidian University 710071 Xi’an China 3. Computer Center Xi’an Communication College 710106 Xi’an China

A new family of windows is constructed by convolutions via a few rectangular windows with same time width and is thus referred to as convolution windows. The expressions of the second-order up to the eighth-order convolution windows in both the time and frequency domains are derived. Their applications in high accuracy harmonic analysis of periodic signals are investigated. Comparisons between the proposed windows and some known windows with the same width shows that, when the synchronous deviation of data sampling is slight, the proposed ones have the least effect of spectral leakage. Therefore, the new windows are well suited for high accuracy harmonic analysis and parameter estimation for periodic signals. The error analysis and computer simulations show that the estimation errors, corresponding to frequency, amplitude and phase of every harmonic component of a signal, are proportional to the pth power of the relative frequency deviation in case of the pth-order convolution window is applied to windowing signal of approximately p cycles. By introducing real time adjustment in sampling interval, the proposed algorithm can adaptively trace signal frequency and lead to less sampling synchronous deviation. The proposed approach has the advantages of easy implementation and high measure precision and can be used in harmonic analysis of quasi-periodic signals whose fundamental frequency drifts slowly with time.

关键词： signal processing harmonic analysis window function convolution window synchronous error spoctral leakage

Generation and controlling of the dispersive wave by femtosecond pulses propagating in the normal dispersion regimes of the birefringent photonic crystal fiber

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science China(Physics,Mechanics & Astronomy) 2010年第4期53卷 643-648页

作者： LI ShuGuang1,2. ZHENG Yi1, YIN GuoBing2. ZHANG Lei2. ZHOU GuiYao2.& HOU LanTian2.1 School of science, Beijing Jiaotong University, Beijing 100044, China 2.key {2. of Metastable Materials science and Technology, College of science, Yanshan University, Qinhuangdao 066004, China 1. School of science Beijing Jiaotong University Beijing 100044 China2. Key Laboratory of Metastable Materials Science and Technology College of Science Yanshan University Qinhuangdao 066004 China

This paper studies the generation of the dispersive wave (DW) in the normal dispersion regimes of the birefringent photonic crystal fiber (BPCF) fabricated in this work. The remarkable blue-shifted radiation is found to be generated when 30 fs pulses are input in the normal dispersion regime of the BPCF for the first time. The characteristics of the blue-shifted DW strongly depend on the polarization of the input pulse. As a result, two peaks appear in the blue-shifted region of the spectrum when the input pulses polarize along the slow axis of the BPCF. With the increase of the center wavelength of the initial input pulse, the difference between the wavelengths of the two peaks widens. The peak location in the spectrum can be explained by the phase matching condition between the DW and the input pulse. In addition, when the input polarization is set to an angle of 45° with respect to the principal axes of the BPCF, the cross-phase modulation and coherent coupling between two orthogonally polarized modes would result in pulse trapping in the BPCF. Accordingly, the DW shift toward short wavelength is restrained. The DW generation in the normal-dispersion regimes of BPCF can be controlled by the phase matching condition and polarization of the input pulse.

关键词： birefringent photonic crystal fiber normal dispersion dispersive wave pulse trapping

Study on the bulk wave radiation of finite-length SAW devices using FEM/BEM

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Progress in Natural science:Materials International 2005年第5期15卷 402-406页

作者： WANG Weibiao1*, ZHANG Xiaodong1, SHUI Yongan1, ZHANG De1 and HAN Tao2.1. State key laboratory of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 2.0093, China 2. Shanghai Jiaotong University, Shanghai 2.0030, China) State key laboratory of Modern Acoustics Institute of Acoustics Nanjing University Nanjing 210093 China Shanghai Jiaotong University Shanghai 200030 China

Based on the distributions of stress and free charge on the interface of the surface acoustic wave (SAW) device calculated with the combination of boundary element method and finite element method(FEM/BEM), the power of each of the three possible bulk waves radiated by the SAW device is calculated, and their contributions to the overall input conductance are separated respectively. Moreover, the formula of angular distributions of their power radiation into the substrate is derived. Consider the effect of mass loading, the resistance density,defined as a scalar, is extended to generalized resistance densities which can be written as three 4×4 tensors and for which the formulas are derived. The bulk wave radiations for a synchronous one-port resonator on 42.Y-rotated LiTaO 3 are simulated. It is found that the radiated energy by slow shear wave contributes a very high proportion to input electrical energy in some frequency range.

关键词： SAW device bulk wave radiation FEM/BEM.

Transition Temperature of Bi_2.r_2.aCu_2._(8+x) Superconducting Films Prepared from Commercial Precursors

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稀有金属材料与工程 2011年第S3期40卷 368-371页

作者： Bi Yue1, Wang Sansheng1, Hao Qingbin2.1 Inertial technology key laboratory of {2. science for National Defense, Beihang University, Beijing 100191, China 2.Northwest Institute for Nonferrous Metal Research, Xi,an 710016, China Beihang Univ Sch Instrument Sci & Optoelect Engn Inertial Technol Key Lab Fundamental Sci Natl Def Beijing 100191 Peoples R China NW Inst Nonferrous Met Res Xian 710016 Peoples R China

This paper have made a systematic study of the superconducting Bi-2.12.phase transition temperature, which has a transition temperature (Tc) around 80-93 K, and depends on precise control of synthesis conditions, mainly including heat treatment parameters, oxygen partial pressure, and annealing temperature. Partial melting of the sample during preparation helps to raise its Tc. To elucidate the origin of this strong effect, the samples were heated with different melting process. The rapid changes in Tc value are associated with small changes in oxygen content, which depends on the annealing temperature and the oxygen partial pressure. We have optimized the above mentioned parameters for Bi-2.12.film, and Tconset was improved to 93 K.

关键词： Bi-2.12 phase partial melt process transition temperature

Pegmatite remote sensing extraction and metallogenic prediction in Azubai area,Xinjiang

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中国有色金属学会会刊：英文版 2011年第S3期21卷 543-548页

作者： PENG Guang-xiong1, 2. YE Zhen-chao1, 2. GAO Guang-ming1, 2. FENG De-shan1, XIONG Yun1 1. School of Geosciences and Info-Physics, Central South University, Changsha 410083, China 2. key {2. of Metallogenic Prediction of Nonferrous Metals, Ministry of Education, Changsha 410083, China [a] School of Geosciences and Info-Physics Central South University Changsha 410083 China [b] key laboratory of Metallogenic Prediction of Nonferrous Metals Ministry of Education Changsha 410083 China

Remote sensing technique plays an important role in geological prospecting in Altay because of the remote location and steep terrain with mountains. Pegmatite has important implications for metallogenic prospecting as most of rare metals occurs in it. Pegmatite information from optical and radar images was extracted, and the spatial distribution and scale of pegmatite were generalized in Azubai, Altay. Three mining targets, that is, Halon-Azubai, Kuermutu-Tuyibaguo and Zhuolute-Akuoyige, were delineated based on the analysis of pegmatite information, structure interpretation and other geological data.

关键词： pegmatite remote sensing information extraction metallogenic prediction

On the placement of actuators and sensors for flexible structures with closely spaced modes

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science China(Technological sciences) 2010年第7期53卷 1973-1982页

作者： LIU XiaoXiang1,2.& HU Jun1,2.1 Beijing Institute of Control Engineering, Beijing 100190, China 2.State key laboratory of {2. and Technology on Space Intelligent Control, Beijing 100190, China 1. Beijing Institute of Control Engineering Beijing 100190 China2. State Key Laboratory of Science and Technology on Space Intelligent Control Beijing 100190 China

This paper analyzed the fundamental limitations of previous work and developed a new method to optimally locate actuators and sensors for structures with close modes. Optimization criteria were defined based on the distinguishing modal controllability and observability measures of close modes. An appropriate genetic algorism was adopted as the optimization algorism. Solving the high order Lyapunov functions was avoided by means of the closed-form expressions for controllability and observability Grammians. Since structure with widely separated natural frequencies is approximately balanced, computational efficiency was improved by grouping close modes together and dealing with the resulting subsystems independently. Finally, the effectiveness and optimality of the novel placement scheme were verified on a model structure with close modes.

关键词： close modes controllability/observability sensor/actuator optimization criterion optimization algorithm

Compression behavior of Zr_(41)Ti_(14)Cu_(12.5)Ni_(10)Be_(2..5) bulk metallic glass up to 2. GPa

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science China(Physics,Mechanics & Astronomy) 2005年第3期48卷 319-324页

作者： LI Gong 1, 2., ZHAN Zaiji 2., LIU Jing 3 , YUN Jinku 1 , SUN Liling 2., LIU Riping 1 , ZHANG Jun 2.& WANG Wenkui 1, 2.1. key laboratory of Metastable Materials {2. and Technology, Yanshan University, Qinhuangdao 066004, China 2. Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of {2.s, Beijing 100080, China 3. BSRF, Institute of High Energy Physics, Chinese Academy of {2.s, Beijing 100039, China 1. key laboratory of Metastable Materials {2. and Technology Yanshan University 066004 Qinhuangdao China 2. Center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences 100080 Beijing China 3. BSRF Institute of High Energy Physics Chinese Academy of Sciences 100039 Beijing China

The compression of a Zr41Ti14Cu12.5Ni10Be2..5 bulk metallic glass (BMG) is investigated at room temperature up to 2. GPa using in-situ high pressure energy dispersive X-ray diffraction with a synchrotron radiation source. The pressure-induced structural relaxation is exhibited. It is found that below about 8 GPa, the existence of excess free volume contributes to the rapid structural relaxation, which gives rise to the rapid volumetric change, and the structural relaxation results in the structural stiffness under higher pressure.

关键词： bulk metallic glass, high pressure, structural relaxation, synchrotron radiation.

Degradation of 4-chlorophenol in aqueous solution by γ-radiation and ozone oxidation

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science China Chemistry 2006年第2期49卷 186-192页

作者： HU Jun1, WANG Jianlong1,2.& CHEN Rong1 1. laboratory of Environmental Technology, Institute of Nuclear Energy Technology, Tsinghua University, Beijing 100084, China 2. State key Joint laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China Correspondence should be addressed to Wang Jianlong 1. laboratory of Environmental Technology Institute of Nuclear Energy Technology Tsinghua University Beijing 100084 China 2. State key Joint laboratory of Environmental Simulation and Pollution Control Tsinghua University Beijing 100084 China

The degradation of 4-chlorophenol (4-CP) by using gamma rays generated by a 60Co source in the presence of O3 was investigated. The radiolysis of 4-CP and the kinetics of 4-CP min-eralization were analyzed based on the determination of total organic carbon (TOC). The influence of initial 4-CP concentration and the free radicals scavengers (such as NaHCO3 and t-butanol) on the 4-CP degradation was also studied. The results showed that when the radiation rate was 336 Gy·min?1, 4-chlorophenol at concentration of 10 mg·L?1 could be completely degraded at the radiation dose of 2.kGy. The degradation of 4-chlorophenol could be described by a first-order reaction model, the rate constant of 4-CP degradation by combined ozonation and radiation was 0.1016 min?1, which was 2.4 times higher than the sum of radiation (0.02.4 min?1) and ozonation (0.0137 min?1). It re-vealed that the combination of radiation and ozonation resulted in synergistic effect, which can re-markably increase the degradation efficiency of 4-CP.

关键词： radiolysis, 4-chlorophenol, priority pollutant, degradation, O3, synergistic effect, kinetics.

Tissue P systems with cell separation: attacking the partition problem

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science China(Information sciences) 2011年第2期54卷 293-304页

作者： ZHANG XingYi1, WANG Shuo2. NIU YunYun2.& PAN LinQiang2.1key Lab of Intelligent Computing and Signal Processing of Ministry of Education, School of Computer science and Technology, Anhui University, Hefei 2.0039, China 2.mage Processing and Intelligent Control key laboratory of Education Ministry of China, Department of Control science and Engineering, Huazhong University of science and Technology, Wuhan 430074, China 1. key Lab of Intelligent Computing and Signal Processing of Ministry of Education School of Computer Science and Technology Anhui University Hefei 230039 China2. Image Processing and Intelligent Control Key Laboratory of Education Ministry of China Department of Control Science and Engineering Huazhong University of Science and Technology Wuhan 430074 China

Tissue P systems are distributed parallel and non-deterministic computing models in the framework of membrane computing, which are inspired by intercellular communication and cooperation between neurons. Recently, cell separation is introduced into tissue P systems, which enables systems to generate an exponential workspace in a polynomial time. In this work, the computational power of tissue P systems with cell separation is investigated. Specifically, a uniform family of tissue P systems with cell separation is constructed for effciently solving a well-known NP-complete problem, the partition problem.

关键词： membrane computing tissue P system cell separation partition problem