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Effects of built-in electric field and donor impurity on linear and nonlinear optical properties of wurtzite InxGa1-xN/GaN nanostructures

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Chinese Physics B 2020年第8期29卷 479-484页

作者： xiao-chen yang Yan Xing School of Physical Science and Technology Inner Mongolia UniversityHohhot 010021China

The linear and nonlinear optical absorption coefficients(ACs)and refraction index changes(RICs)of 1s-1p,1p-1d,and 1f-1d transitions are investigated in a wurtzite InxGa1-xN/GaN core-shell quantum dot(CSQD)with donor impurity by using density matrix *** effects of built-in electric field(BEF),ternary mixed crystal(TMC),impurity,and CSQD size are studied in *** finite element method is used to calculate the ground and excited energy state energy and wave *** results reveal that the BEF has a great influence on the linear,nonlinear,and total ACs and *** presence of impurity leads the resonant peaks of the ACs and RICs to be blue-shifted for all transitions,especially for 1s-1p *** is also found that the resonant peaks of the ACs and RICs present a red shift with In-composition decreasing or core radius ***,the amplitudes of the ACs and RICs are strongly affected by the incident optical *** absorption saturation is more sensitive without the impurity than with the impurity,and the appearance of absorption saturation requires a larger incident optical intensity when considering the BEF.

关键词： core-shell quantum dot linear and nonlinear optical properties impurity ternary mixed crystal

Joint probability distribution of winds and waves from wave simulation of 20 years (1989-2008) in Bohai Bay

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Water Science and Engineering 2013年第3期6卷 296-307页

作者： xiao-chen yang Qing-he ZHANG State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin University

The joint probability distribution of wind speed and significant wave height in the Bohai Bay was investigated by comparing the Gurnbel logistic model, the Gumbel-Hougaard （GH） copula function, and the Clayton copula function. Twenty years of wind data from 1989 to 2008 were collected from the European Centre for Medium-Range Weather Forecasts （ECMWF） database and the blended wind data of the Quick Scatterometer （QSCAT） satellite data set and re-analysis data from the United States National Centers for Environmental Prediction （NCEP）. Several typhoons were taken into account and merged with the background wind fields from the ECMWF or QSCAT/NCEP database. The 20-year data of significant wave height were calculated with the unstructured-grid version of the third-generation wind wave model Simulating WAves Nearshore （SWAN） under extreme wind process conditions. The Gumbel distribution was used for univariate and marginal distributions. The distribution parameters were estimated with the method of L-moments. Based on the marginal distributions, the joint probability distributions, the associated return periods, and the conditional probability distributions were obtained. The GH copula function was found to be optimal according to the ordinary least squares （OLS） test. The results show that wind waves are the prevailing type of wave in the Bohai Bay.

关键词： wind speed wave simulation joint probability distribution copula function,conditional probability distribution

A rotary ultrasonic motor using radial bending mode of ring with nested PZT excitation

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第3期13卷 189-196页

作者： Ying-xiang LIU Jun-kao LIU Wei-shan chen xiao-hui yang State Key Laboratory of Robotics and System Harbin Institute of Technology Horbin 150001 China

This study presents and verifies a new idea for constructing a rotary traveling wave ultrasonic motor （USM） that uses the radial bending mode of a ring. In the new design, 20 trapezoid cross section slots are cut symmetrically in the outer surface of a thick duralumin alloy ring, where 20 PZT stacks are nested. In each slot, two wedging blocks are set between the PZT stack and the two sides of the slot respectively to apply preloading on the PZT ceramics. Two radial bending modes of the stator that have a phase difference of a quarter wavelength on space are generated by using the d33 operating mode of the PZT elements, and then a flexural traveling wave is formed by the superimposing of two standing waves whose amplitudes are equal and phases are different by 90~ temporally. Two conical rotors are pressed to each end of the ring type stator by a coiled spring. The finite element method （FEM） simulation is developed to validate the feasibility of the proposed motor. The maximal speed and torque of the prototype are tested to be 126 r/rain and 0.8 N＇m, respectively.

关键词： Rotary ultrasonic motor Radial bending mode Traveling wave Wedging block clamped structure

Commissioning and operation of the cryostat for 3W1 SC wiggler

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Nuclear Science and Techniques 2023年第6期34卷 43-54页

作者： Miao-Fu Xu Xiang-Zhen Zhang Rui Ye Jin-Can Wang xiao-Juan Bian Yao Gao Min-Xian Li Fu-San chen xiao-chen yang Rui Ge Institute of High Energy Physics Chinese Academy of SciencesBeijing100049China Key Laboratory of Particle Acceleration Physics and Technology Chinese Academy of SciencesBeijing100049China Center for Superconducting RF and Cryogenics Institute of High Energy PhysicsBeijing100049China University of Chinese Academy of Sciences Beijing100049China

A 3W1 superconducting wiggler(SCW)with the pole gap of 68 mm was successfully tested and installed in a BEPC II storage ring in November,*** goal of zero liquid helium consumption was achieved,and the cryogenic system exhibited a 12%residual cooling capacity(approximately 0.69 W@4.2 K).The 3W1-SCW was set to operate at 2.49 T and has been operating for more than seven *** instances of magnet quenching occurred during the normal *** evaporated helium gas can be recycled to the helium gas recycling system when the pressure in the helium tank is higher than the parameter value(the setpoint of the pressure value is 1.2 bara).The cryogenic system can be recovered within 4 h if sufficient liquid helium is available to inject into the cryostat.

关键词： Cryostat Commissioning SC wiggler Synchrotron radiation

Activation Energy for Superplastic Flow Above Critical Temperature of Die Steels

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Journal of Iron and Steel Research International 2006年第5期13卷 4-6页

作者： WEN Jiu-ba ZHANG Ke-ke chen Fu-xiao yang Yong-shun School of Materials Science and Engineering Henan University of Science and Technology Luoyang 471003 Henan China

Some commercial cold working die steels C.,Cr15 and CrWMn with ultra fine grain size were chosen as tested materials to research the activation energy for superplastic flow at different temperatures and strain rates above critical temperature. Based on the Arrhenius equation, the activation energy for superplastic flow is evaluated. The activation energy at constant strain rate is estimated by the logσ, vs 1/T relationship. The results show that the ac tivation energy is usually small under the conditions of optimal flow. The characteristics of superplastic deformation of steels above the critical temperature were also analyzed.

关键词： superplasticity superplastic working activation energy

Spatial Interpolation of Soil Texture Using Compositional Kriging and Regression Kriging with Consideration of the Characteristics of Compositional Data and Environment Variables

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Journal of Integrative Agriculture 2013年第9期12卷 1673-1683页

作者： ZHANG Shi-wen SHEN Chong-yang chen xiao-yang YE Hui-chun HUANG Yuan-fang LAI Shuang China Agricultural University/Key Laboratory of Arable Land Conservation (North China) Minstry of Agriculture/Key Laboratory of Agricultural Land Quality MonitoringMinistry of Land and Resources School of Earth and Environment Anhui University of Science and Technology Afforestation Management Office Sichuan Forestry Department

The spatial interpolation for soil texture does not necessarily satisfy the constant sum and nonnegativity constraints. Meanwhile, although numeric and categorical variables have been used as auxiliary variables to improve prediction accuracy of soil attributes such as soil organic matter, they （especially the categorical variables） are rarely used in spatial prediction of soil texture. The objective of our study was to comparing the performance of the methods for spatial prediction of soil texture with consideration of the characteristics of compositional data and auxiliary variables. These methods include the ordinary kriging with the symmetry logratio transform, regression kriging with the symmetry logratio transform, and compositional kriging （CK） approaches. The root mean squared error （RMSE）, the relative improvement value of RMSE and Aitchison＇s distance （DA） were all utilized to assess the accuracy of prediction and the mean squared deviation ratio was used to evaluate the goodness of fit of the theoretical estimate of error. The results showed that the prediction methods utilized in this paper could enable interpolation results of soil texture to satisfy the constant sum and nonnegativity constraints. Prediction accuracy and model fitting effect of the CK approach were better, suggesting that the CK method was more appropriate for predicting soil texture. The CK method is directly interpolated on soil texture, which ensures that it is optimal unbiased estimator. If the environment variables are appropriately selected as auxiliary variables, spatial variability of soil texture can be predicted reasonably and accordingly the predicted results will be satisfied.

关键词： compositional kriging auxiliary variables regression kriging symmetry logratio transform

Phenotypic variation in thirteen native provenances of Lespedeza bicolor Turcz

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Forestry Studies in China 2007年第4期9卷 272-278页

作者： Pian Rui-qi Zhao yang Li Wei chen xiao-yang Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants Ministry of Education Beijing Forestry University Beijing 100083 P. R. China Forestry College Guizhou University Guiyang 550025 E R. China Forestry College South China Agricultural University Guangzhou 510642 E R. China

Lespedeza bicolor Turcz is a native shrub in the temperate region of China. Thirteen provenances of L. bicolor were investigated in our study. Morphological diversity among and within provenances were analyzed based on 19 phenotypic traits, including seven vegetative growth characteristics, nine floral traits and three pod characteristics. The coefficient of variation （CV） ranged from 6.4% to 65.4% and the phenotypic differentiation coefficient from 43.3% to 97.3%. Analyses of variance showed that there were extremely significant variations among and within provenances in pod length. Differences in plant height, inter-nodal length, number of branches, leaf width, leaf length and leaf area were not remarkable among provenance, but distinct within provenances. Other traits showed evidence of contrasts. Variation among provenances was the main part of phenotypic variation. Correlation analysis indicated that there were highly significant positive correlations between plant height and other vegetative growth characteristics. Floral traits were not associated with vegetative growth characteristics. The 13 provenances of L. bicolor investigated can be classified into three groups according to a UPGMA cluster analysis.

关键词： Lespedeza bicolor phenotypic variation analysis of variance correlation analysis cluster analysis

RNA interference and its application in plants

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Forestry Studies in China 2008年第4期10卷 280-284页

作者： ZHOU Bing-bin LI Wei chen xiao-yang Key Laboratory for Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education Beijing Forestry University Beijing 100083 P. R. China

RNA interference （RNAi）, a process that inhibits gene expression by the double-stranded RNA （dsRNA）, causes the degradation of target messenger RNA molecules. RNAi exists in almost all organisms. We review the recent history of RNAi studies, RNAi molecular mechanisms, characteristics and RNAi applications in higher plants. At the same time, the prospect of RNAi applications in functional genomics and genetic improvement of higher plants and possible future problems and possibilities are also discussed.

关键词： RNA interference functional genomics genetic improvement antivirus

Construction of Recombinant Modified Vaccinia Ankara(MVA) Expressing Hepatitis B Virus Surface Antigen

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Chemical Research in Chinese Universities 2006年第2期22卷 213-216页

作者： chen Yu yang xiao-song YU Xiang-hui JIANG Chun-lai WU Yong-ge JIN Ying-hua chen Yue chen Yan LI Wei KONG Wei Vaccine Research Center College of Life Science Jilin University Changchun 130012 P. R. China

The T lymphocyte response has been shown to be the determinant in the clearance of many viral infections. Hence, therapeutic vaccine candidates against HBV are designed to enhance this response of the immune system. Vaccinia virus vector-based vaccines have been proposed as excellent candidates to elicit long-term and strong T lymphocyte mediated immune responses. In this study, the recombinant MVA expressing HBV surface antigen has been constructed, which can elicit a potent T cell mediated response. The ELISA results for the surface protein in the medium of the recombinant MVA, strongly indicate that the recombinant virus has been successfully obtained.

关键词： Recombinant MVA Therapeutic vaccine T lymphocyte response