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Wavelet-based method for computing elastic band gaps of one-dimensional phononic crystals

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Science China(Physics,Mechanics & Astronomy) 2007年第5期50卷 622-630页

作者： YAN zhizhong wang YueSheng Institute of Engineering Mechanics Beijing Jiaotong University Beijing 100044 China Institute of Engineering Mechanics Beijing Jiaotong University Beijing 100044 China

A wavelet-based method was developed to compute elastic band gaps of one-dimensional phononic crystals. The wave field was expanded in the wavelet basis and an equivalent eigenvalue problem was derived in a matrix form involving the adaptive computation of integrals of the wavelets. The method was then applied to a binary system. For comparison, the elastic band gaps of the same one-dimensional phononic crystals computed with the wavelet method and the well- known plane wave expansion (PWE) method are both presented in this paper. The numerical results of the two methods are in good agreement while the computation costs of the wavelet method are much lower than that of PWE method. In addition, the adaptability of wavelets makes the method possible for efficient band gap computation of more complex phononic structures.

关键词： phononic crystals, elastic band gap, wavelet method, plane wave expansion (PWE) method

First spike latency of ON/OFF neurons in the optic tectum of pigeons

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Integrative Zoology 2019年第5期14卷 479-493页

作者： Songwei wang Mengke wang zhizhong wang Li SHI School of Electrical Engineering Zhengzhou UniversityZhengzhouHenanChina Industrial Technology Research Institute Zhengzhou UniversityZhengzhouHenanChina Department of Automation Tsinghua UniversityBeijingChina

Some shallow and middle optic tectum(OT)neurons have stable,asymmetric full-screen ON and OFF stimulus response properties,which makes them candidates for delay *** this paper,we investigated the delay encoding mechanism for the neuronal clusters in the OT region of pigeons and determined the mechanism of delay coding in the OT *** analyzing the responses of the neuron cluster under full-screen switch-on and switch-off stimulation,we found that the delay coding was widespread in the OT region where the ON/OFF stimulation time difference was 4-6 *** theory analysis under grating stimulation and experiments based on single-neuron character reconstruction of neurons showed that OT neuron clusters use the first spike latency(FSL)for the rapid transfer of spatial structure ***,4 models were used to predict the first spike latency of these OT *** best simulation results were obtained using an architecture where the ON and OFF paths of multiple retinal ganglion cells(RGCs)were integrated and summed,respectively.

关键词： delayed encoding information theory model optic tectum

Preparation,Characterization,and Catalytical Application of MgCoAl-Hydrotalcite-Like Compounds

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Journal of Natural Gas Chemistry 2007年第4期16卷 371-376页

作者： Kai Yan Xianmei Xie Jinping Li Xiulan wang zhizhong wang College of Chemistry and Chemical Engineering Taiyuan University of Technology Taiyuan 030024 Shanxi China

MgCoAl-hydrotalcite-like compounds （MgCoAI-HTLcs） were synthesized using the coprecipitation method of variable pH values. The effect of each factor on the preparation of HTLcs was discussed systematically, which included pH values, mole ratios of Mg2＋ to Co2＋, the concentrations of the solution, and the temperature and time of the hydrothermal treatment. Besides, the thermal decomposition of MgCoAI-HTLcs was discussed. X-ray diffraction, thermogravimetric analysis, and FT-IR spectroscopy were performed to characterize the MgCoAI-HTLcs samples. The results showed that when the pH = 7.6-8.5 or 5.5-6.2, atomic ratios of （Mg^2＋＋Co2＋）/Al^3＋ 2 and Mg^2＋/Co^2＋ ranging from 1.00 to 2.00, temperature and time of hydrothermal treatment being 110℃ and 6 h, unique MgCoAI-HTLcs with high crystallinity could be obtained. When the calcination temperature was up to 250℃, the MgO phase was detected coexisting with Al2O3 and MgAl2O4 was highly spreaded on the derived mixed oxides. The synthesis reaction of benzoin methyl ether with methanol and benzaldehyde was chosen to study the catalytic activity of MgCoAI-HTLcs. The catalyst showed high activity and high stability in the synthesis of benzoin methyl ether in the feasible condition.

关键词： MgCoAl-hydrotalcite-like compounds preparation benzoin methyl ether methanol benzaldehyde

Section thickness-dependent tensile properties of squeeze cast magnesium alloy AM60

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China Foundry 2012年第2期9卷 178-183页

作者： Xuezhi Zhang Meng wang zhizhong Sun Henry Hu Department of Mechanical Automotive and Materials Engineering University of Windsor Windsor Ontario N9B 3P4 Canada

The development of alternative casting processes is essential for the high demand of light weight magnesium components to be used in the automotive industry, which often contain different section thicknesses. Squeeze casting with its inherent advantages has been approved for the capability of minimizing the gas porosity in magnesium alloys. For advanced engineering design of light magnesium automotive applications, it is critical to understand the effect of section thickness on mechanical properties of squeeze cast magnesium alloys. In this study, magnesium alloy AM60 with different section thicknesses of 6, 10 and 20 mm squeeze cast under an applied pressure of 30 MPa was investigated. The prepared squeeze cast AM60 specimens were tensile tested at room termperature. The results indicate that the mechanical properties including yield strength （YS）, ultimate tensile strength （UTS） and elongation （A） decrease with an increase in section thickness of squeeze cast AM6O. The microstructure analysis shows that the improvement in the tensile behavior of squeeze cast AM60 is primarily attributed to the low-gas porosity level and fine grain strucuture which result from the variation of cooling rate of different section thickness. The numerical simulation （Magmasoft） was employed to determine the solidification rates of each step, and the simulated results show that the solidification rate of the alloy decreases with an increase in the section thickness. The computed solidification rates support the experimental observation on grain structural development.

关键词： squeeze casting magnesium alloy AM60 tensile properties section thickness

Detection of a temporal salient object benefits from visual stimulus-specific adaptation in avian midbrain inhibitory nucleus

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Integrative Zoology 2024年第2期19卷 288-306页

作者： Jiangtao wang Xiaoping RAO Shuman HUANG zhizhong wang Xiaoke NIU Minjie ZHU Songwei wang Li SHI Department of Automation Zhengzhou University School of Electrical EngineeringZhengzhouChina State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics National Center for Magnetic Resonance in WuhanKey Laboratory of Magnetic Resonance in Biological SystemsInnovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhanChina Department of Automation Tsinghua UniversityBeijingChina

Food and predators are the most noteworthy objects for the basic survival of wild animals,and both are often deviant in both spatial and temporal domains and quickly attract an animal’s *** stimulus-specific adaptation(SSA)is considered a potential neural basis of salient sound detection in the temporal domain,related research on visual SSA is limited and its relationship with temporal saliency is *** avian nucleus isthmi pars magnocellularis(Imc),which is central to midbrain selective attention network,is an ideal site to investigate the neural correlate of visual SSA and detection of a salient object in the time ***,the constant order paradigm was applied to explore the visual SSA in the Imc of *** results showed that the firing rates of Imc neurons gradually decrease with repetitions of motion in the same direction,but recover when a motion in a deviant direction is presented,implying visual SSA to the direction of a moving ***,enhanced response for an object moving in other directions that were not presented ever in the paradigm is also *** verify the neural mechanism underlying these phenomena,we introduced a neural computation model involving a recoverable synaptic change with a“center-surround”pattern to reproduce the visual SSA and temporal saliency for the moving *** results suggest that the Imc produces visual SSA to motion direction,allowing temporal salient object detection,which may facilitate the detection of the sudden appearance of a predator.

关键词： adaptation attention model pigeon saliency

Preparation of Small Particle Sized ZnAl-Hydrotalcite-Like Compounds by Ultrasonic Crystallization

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Journal of Natural Gas Chemistry 2006年第2期15卷 100-104页

作者： Xianmei Xie Xiurong Ren Jinping Li Xiaojun Hu zhizhong wang College of Chemical Engineering ＆ Technology Taiyuan University of Technology Taiyuan 030024 China

Ultrasonic technology has been intensively studied recently due to its special features. In this paper, an ultrasonic crystallization method was introduced for the preparation of ZnAl-Hydrotalcite-Like compounds （ZnAl-HTLcs）. Samples with high crystallinity, small particle size and narrow particle size distribution were obtained and fully characterized using conventional techniques of XRD, FT-IR and TGDTA. The results prove that both ultrasonic frequency and ultrasonic power have effects on the sizes of the product particles. By varying the ultrasonic power from 250 W to 88 W, with the ultrasonic frequency fixed at 59 kHz, the median particle size of the samples increased from 0.37 μm to 0.82 μm. By altering the hydrothermal treatment time from 1 h to 5 h at 110 ℃, the median particle size of ZnAl-HTLcs synthesized via ultrasonic crystallization increased from 0.88 μm to 1.11 μm.

关键词： ultrasonic crystallization particle size distribution zinc aluminium

Visual cognition of birds and its underlying neural mechanism:A review

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Avian Research 2022年第2期13卷 216-225页

作者： Xiaoke Niu Zhenyang Jiang Yanyan Peng Shuman Huang zhizhong wang Li Shi Henan Key Laboratory of Brain Science and Brain-Computer Interface Technology School of Electrical EngineeringZhengzhou UniversityZhengzhou450001China Department of Automation Tsinghua UniversityBeijing100084China

Birds have acute vision and many remarkable visual cognition abilities,due to their unique living *** underlying neural mechanisms have also attracted interests of researchers in ***,we firstly summarize the visual cognition abilities of birds,and make a comparison with ***,the underlying neural mechanisms are presented,including histological structure of avian brain and visual pathways,typical experimental results and conclusions in electrochemistry and *** latter mainly focuses on several higher brain areas related to visual cognition,including mesopallium ventrolaterale,entopallium,visual Wulst,and nidopallium ***,we make a conclusion and provide a suggestion about future studies on revealing the neural mechanisms of avian visual *** review presents a detailed understanding of avian visual cognition and would be helpful in ornithology studies in the field of cognitive neuroscience.

关键词： Avian Electrophysiology Neural mechanism Visual cognition

Superconducting State Volume in High T_(c) Superconductor and Non-resonant Microwave Absorption

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Chinese Physics Letters 1992年第3期9卷 155-158页

作者： HOU Bihui wang zhizhong Department of Physics University of Science and Technology of ChinaHefei 230026

The mechanism of low-field non-resonant microwave absorption is speculated,and it is exposed that the magnitude of the microwave signal indicates the superconducting state volume in the shell lying along inner surface... 详细信息

关键词： microwave resonant Absorption

TESTING SERIAL CORRELATION IN SEMIPARAMETRIC VARYING COEFFICIENT PARTIALLY LINEAR ERRORS-IN-VARIABLES MODEL

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Journal of Systems Science & Complexity 2009年第3期22卷 483-494页

作者： Xuemei HU Feng LIU zhizhong wang Mathematics and Statistics College Chongqing Technology and Business University Chongqing 400067 China. School of Mathematics and Physics Chongqing InsLitu$e of Technology Chongqing 400050 China. School of Mathematics and Computing Technology Central South University Changsha 410075 China.

The authors propose a V_(N,p) test statistic for testing finite-order serial correlation in asemiparametric varying coefficient partially linear errors-in-variables *** test statistic is shownto have asymptotic normal distribution under the null hypothesis of no serial *** MonteCarlo experiments are conducted to examine the finite sample performance of the proposed V_(N,p) *** results confirm that the proposed test performs satisfactorily in estimated sizeand power.

关键词： Asymptotic normality local linear regression measurement error modified profile leastsquares estimation partial linear model testing serial correlation varying coefficient model.