检索结果-南通市图书馆

Quantum properties of the binomial state field interacting with a two-level atom

在线全文

学校读者我要写书评

暂无评论

science china(Physics,Mechanics & Astronomy) 2010年第5期53卷 864-869页

作者： JIANG DaoLai,REN XueZao,CONG HongLu & li Lei School of science,southwest university of science and technology,mianyang 621010,china 1. School of science Southwest University of Science and Technology Mianyang 621010 China

By the method of coherent-state orthogonalization expansion,the atomic inversion and the anti-bunching effect in a two-level atomic system interacting with binomial state field are studied under the Jaynes-Cummings model without rotating wave *** influence of the parameter and the detuning on the anti-bunching effect are discussed,and the anti-bunching effect is also discussed under the conditions of strong *** studies show that the second order coherence degrees are quite different between the situations of with and without-rotating wave *** the latter when the detuning increases,the duration of the bunching effect increases at the beginning and then decreases,and finally the light field displays anti-bunching effect completely.

关键词： coherent state orthogonalization expansion binomial state field Jaynes-Cummings model without-rotating wave approximation atomic inversion

Combustion Synthesis and Luminescent Properties of CaO: Eu^(3+), M^+ (M=li, Na, K) Phosphor

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials science) 2010年第2期25卷 179-183页

作者：康明 College of Material science and Engineering Southwest University of Science and Technology

li ^＋ , Na^ ＋ , or K ^＋ co-doped CaO： Eu^3＋ phosphors were prepared by the combustion synthesis method and characterized by X-ray diffraction （XRD）, photoluminescence and photolumi-nescence excitation （PL-PLE） spectra. The experimental results show that, upon excitation with 250 nm xenon light, the emission spectrum of the CaO： Eu^3＋ consists of 4f-4f emission transitions from the 5D0 excited level to the 7FJ （J=1, 2, 3） levels with the mainly electric dipole transition 5D0→7F2 of Eu3＋, indicating that the Eu^3＋ occupies a low symmetry. The charge-transfer band （CTB） shows somewhat red shift with the decreasing ionic radii of co-doped alkali metal ions. The PL and PLE intensities are significantly enhanced, especially the strongest intensity of luminescent is CaO： Eu^3＋, li ＋ phosphor, when alkali metal ions are incorporated. The strongest peak of emission is slightly shifted from 614 to 593 nm, indicating that the Eu^3＋ ion locates in a symmetric position （Oh） when alkali metal ions are incorporated.

关键词： luminescence CaO: Eu^3+ combustion method

Entropic stochastic resonance in a confined structure driven by dichotomous noise and white noises

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第8期21卷 71-77页

作者：郭锋程晓锋李少甫曹文黎恒 School of Information Engineering Southwest University of Science and Technology Research Center of Laser Fusion China Academy of Engineering Physics

The entropic stochastic resonance （ESR） in a confined system subjected to dichotomous noise and white noise and driven by a periodic sinusoidal force along the x axis of the structure and a time-dependent force in the declining direction, is investigated. Under the adiabatic approximation condition and based on the two-state theory, the expression of the output signal-to-noise ratio （SNR） is obtained. The results show that the SNR is a non-monotonic function of the strengths of dichotomous noise, white noise, and correlated strength of correlated noise. In addition, the SNR varies non-monotonically with the increase of the shape parameters of the confined structure, and also with the increase of the constant force along the y axis of the structure. The influence of the correlation rate of the dichotomous noise, and that of the frequency of the periodic force on the SNR are discussed.

关键词： entropic stochastic resonance dichotomous noise correlated noise square-wave signal,signal-to-noise ratio

Effects of rare earth La on the microstructure and melting property of(Ag-Cu_(28))-30Sn alloys prepared by mechanical alloying

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2011年第1期30卷 49-52页

作者： li liangfeng QIU Tai YANG Jian FENG Yongbao State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials Southwest University of Science and Technology Mianyang 621010 China College of Materials science and Engineering Nanjing University of Technology Nanjing 210009 China

To obtain novel intermediate temperature alloy solders with a melting temperature of 400-600°C,nominal（Ag-Cu28）-30Sn alloys without or with a trace addition（0.5 or 1.0 wt.%） of rare earth（RE） element La were prepared by mechanical *** aim of this research is to investigate the effects of the addition of La on the microstructures,alloying process and melting properties of（Ag-Cu28）-30Sn *** results show that the addition of La produces no new phase.A trace amount of La addition can effectively refine the grain size,but the excessive addition of 1.0 wt.% La inhibits the alloying *** influence of La on the melting temperatures of solder alloys is ***,the trace addition of 0.5 wt.% La can distinctly reduce the fusion zone and improve the melting property of（Ag-Cu28）-30Sn alloys.

关键词： solders rare earths mechanical alloying microstructure melting

Photoluminescence and cathodoluminescence properties of a novel CaLaGa_3O_7:Dy^(3+) phosphor

在线全文

学校读者我要写书评

暂无评论

Chinese science Bulletin 2012年第7期57卷 827-831页

作者： ZHAO WenYu1,2, AN Shengli1, FAN Bin1, li SongBo1 & DAI YaTang3 1 School of Metallurgical and Ecological Engineering, university of science and technology Beijing, Beijing 100083, china 2 School of Chemistry and Chemical Engineering, Inner Mongolia university of science and technology, Baotou 014010, china 3 School of Materials science and Engineering, southwest university of science and technology, mianyang 621000, china School of Metallurgical and Ecological Engineering University of Science and Technology Beijing School of Chemistry and Chemical Engineering Inner Mongolia University of Science and Technology

A single host white emitting phosphor, CaLaGa3O7:Dy3+, was synthesized by chemical co-precipitation. Field emission scanning electron microscopy, X-ray diffraction, laser particle size analysis, and photoluminescence and cathodoluminescence spectra were used to investigate the structural and optical properties of the phosphor. The phosphor particles were composed of microspheres with a slight tendency to agglomerate, and an average diameter was of about 1.0 μm. The Dy3+ ions acted as luminescent centers, and substituted La3+ ions in the single crystal lattice of CaLaGa3O7 where they were located in Cs sites. Under excitation with ultraviolet light and a low voltage electron beam, the CaLaGa3O7:Dy3+ phosphor exhibited the characteristic emission of Dy3+ (4F9/2-6H15/2 and 4F9/2-6H13/2 transitions) with intense yellow emission at about 573 nm. The chromaticity coordinates for the phosphor were in the white region. The relevant luminescence mechanisms of the phosphor are investigated. This phosphor may be applied in both field emission displays and white light-emitting diodes.

关键词：光致发光阴极射线荧光粉镝离子场发射扫描电子显微镜白色发光二极管特性 X射线衍射仪

Forecast Method of Multimode System for Debris Flow Risk Assessment in Qingping Town,Sichuan Province,china

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain science 2011年第4期8卷 592-602页

作者： KONG Jiming Key Laboratory of Mountain Hazards and Earth Surface Processes Chinese Academy of Sciences Institute of Mountain Hazards and Environment Chinese Academy of Sciences

The Wenchuan Earthquake of May 12,2008 triggered large numbers of *** heavy rain on 13 August 2010 triggered debris flows with total volume of more than 6 million cubic meters and the debris flows destroyed 500 houses and infrastructure built after the Wenchuan *** study area Qingping Town was located in the northwestern part of the Sichuan Basin of china,which needs the second reconstructions and the critical evaluation of debris *** study takes basin as the study unit and defines collapse,landslide and debris flow hazard as a geo-hazard system.A multimode system composed of principal series system and secondary parallel system were established to evaluate the hazard grade of debris flow in 138 drainage basins of Qingping *** evaluation result shows that 30.43% of study basins(42 basins) and 24.58% of study area,are in extremely high or high hazard grades,and both percentage of basin quantity and percentage of area in different hazard grades decrease with the increase of hazard *** to the geo-hazard data from the interpretation of unmanned plane image with a 0.5-m resolution and field investigation after the Wenchuan Earthquake and 8.13 Big Debris Flow,the ratio of landslides and collapses increased after the Wenchuan Earthquake and the ratios of extremely high or high hazard grades were more than moderate or low hazard grades obviously.23 geo-hazards after8.13 Big Debris Flow in Qingping town region all occurred in basins with extremely high or high hazard grades,and 9 debris flows were in basins with extremely high hazard *** model of multimode system for critical evaluation could forecast not only the collapse and landslide but also the debris flow precisely when the basin was taken as the study unit.

关键词： Multimode System Risk assessment Debris flow Landslide Wenchuan Earthquake Qingping Town

Effects of Heat-treatment Temperature on Eu^(3+) and li^+ Co-doped ZnO Photoluminescence by Sol-gel Process

在线全文

学校读者我要写书评

暂无评论

Journal of Wuhan university of technology(Materials science) 2008年第1期23卷 20-23页

作者：卢忠远 HE Fangfang 许丕池 TENG Yuancheng WANG Bing Key Lab for Advanced Building Materials of Sichuan Province Southwest University of Science and Technology Mianyang 621010 China

The photoluminescence （PL） characteristics of Eu^3＋ and li^＋ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emission spectra of all samples showed two broad bands peaking at 590 nm and 620 nm under UV-Vis excitation. But the relative intensity of red PL （620 nm） was much greater than that of green PL （590 nm） of the same sample, that s to say, the red color was the main luminescence. With heat-treatment temperature increase, the two kinds of colors PL intensity decreased, and both the red and green PL intensity of the xerogel samples was much greater than those of powder samples respectively. The XRD patterns revealed that Eu^3＋ ions were successfully incorporated in ZnO crystals in xerogel samples. When heat-treatment temperature reached 350 ℃, the Eu^3＋ began to separate out of the ZnO crystals and Eu2O3 crystals came into being. When the powder sample was subjected to UV-Vis excitation, the energy transfered from the host ZnO emission to Eu^3＋ became weaker than the xerogel sample.

关键词： photoluminescence Eu^3+ and li^+ co-doped ZnO UV-Vis excitation, xerogel powder

在线全文

学校读者我要写书评

暂无评论

悬臂梁式压电振动发电机的建模及仿真

系统仿真学报 2008年第23期20卷 6359-6364页

作者：齐洪东杨涛韩宾胡莉西南科技大学信息工程学院四川绵阳621010

压电振动发电机是一种能量密度大、无污染、结构简单的新型供电装置。从悬臂梁式双压电片机械模型出发,运用压电学和材料力学的基本理论,建立起压电振动发电机的机电耦合模型。将数学模型用传递函数的形式表示,并利用Matlab/Simulink仿... 详细信息

压电振动发电机是一种能量密度大、无污染、结构简单的新型供电装置。从悬臂梁式双压电片机械模型出发,运用压电学和材料力学的基本理论,建立起压电振动发电机的机电耦合模型。将数学模型用传递函数的形式表示,并利用Matlab/Simulink仿真工具直观地得到输入和输出随时间和负载变化的关系。分别分析了阻性负载和容性负载结构特性和输出特性,并与相关文献的实验结果进行对比。通过对仿真结果的分析和对比,验证了该模型建立的正确性,为优化设计提供了基础。

关键词：压电振动发电机机电耦合模型仿真悬臂梁

Anti-swing Control of the Crane System Based on Input Shaping Technique

在线全文

学校读者我要写书评

暂无评论

Anti-swing Control of the Crane System Based on Input Shapin...