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Study on internal quantum efficiency of blue InGaN multiple-quantum-well with an InGaN underneath layer

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Science china(Technological Sciences) 2010年第2期53卷 306-308页

作者： WANG JiaXing, WANG Lai, ZHAO Wei, ZOU Xiang & LUO Yi National laboratory for information Science and Technology/state key laboratory on Integrated Optoelectronics, Department of Electronic Engineering, Tsinghua University, beijing 100084, china National laboratory for information Science and Technology/state key laboratory on Integrated Optoelectronics Department of Electronic Engineering Tsinghua University

Blue InGaN multiple-quantum-well (MQW) samples with different InxGa1-xN (x=0.01–0.04) underneath layers (ULs) were grown by metal organic vapor phase epitaxy (MOVPE). Temperature dependent photoluminescence showed that the InGaN UL can improve the internal quantum efficiency (IQE) of MQW effectively due to strain release. And a maximum IQE of 50% was obtained when the thickness and In content of the InGaN UL were 60 nm and 0.01, respectively. Furthermore, the larger In content or thickness of the InGaN UL makes the IQE lower. Arrhenius fit to the experiment data showed that the IQE fall was mainly caused by the quantity increase of the nonradiative recombination centers, which was believed related to the accumulated stress in InGaN ULs.

关键词： InGaN underneath layer (UL) multiple-quantum-well (MQW) internal quantum efficiency (IQE) Arrhenius formula

Analysis of forest backscattering characteristics based on polarization coherence tomography

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Science china(Technological Sciences) 2010年第S1期53卷 166-175页

作者： LUO HuanMin 1,LI XiaoWen 1,2,CHEN ErXue 3,CHENG Jian 4 & CAO ChunXiang 21 Institute of Geo-Spatial information Science and Technology,University of Electronic Science and Technology of china,Chengdu 610054,china 2 state key laboratory of Remote Sensing Science,Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and beijing Normal University,beijing 100101,china 3Institute of Forest Resources information Technique of Chinese Academy of Forestry,beijing 100091,china 4 School of Electronic Engineering,University of Electronic Science and Technology of china,Chengdu 610054,china Institute of Geo-Spatial information Science and Technology University of Electronic Science and Technology of China Chengdu China state key laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences and Beijing Normal University Beijing China Institute of Forest Resources information Technique of Chinese Academy of Forestry Beijing China School of Electronic Engineering University of Electronic Science and Technology of China Chengdu China

It is difficult to make an inventory of vertical profiles of forest structure parameters in field ***,analysis and understanding of forest backscattering characteristics contribute to estimation and detection of forest vertical structure because of the close relationships between backscattering characteristics and structure *** vertical structure function in the complex interferometric coherence definition,which represents the vertical variation of microwave scattering with the penetration depth at a point in the 2-D radar image and can be used to analyze the forest backscattering characteristics,can be reconstructed from polarization coherence tomography(PCT).Based on PCT,the paper analyzes the forest backscattering characteristics and explores the inherent relationship between the result of PCT and the forest structure parameters from numerical simulation of Random Volume over Ground model(RVoG),Polarimetric SAR interferometry(PolInSAR)simulation of forest scene and PolInSAR data at L-band of the test site ***,the effects of the extinction coefficient and surface-to-volume scattering ratio in RVoG model on vertical backscattering characteristics are analyzed by means of numerical ***,by applying PCT to L-band POLInSAR simulations of forest scene,different variations of vertical backscattering due to different extinction coefficients and the ratios of surface-to-volume scattering resulting from different polarizations,forest types and densities are displayed and *** a concept of relative average backscattering intensity is presented,and the factors which affect its vertical distribution are also *** results show that there is high sensitivity of the vertical distribution of forest relative average backscattering intensity to the polarization,forest type and ***,based on repeat pass DLR E-SAR L-band airborne POLInSAR data,the capability of PCT technology for detection

关键词： backscattering characteristic POLInSAR PCT vertical structure function

Dynamic weighted random load balancing algorithm for SIP application server

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The Journal of china Universities of Posts and Telecommunications 2009年第4期16卷 67-70页

作者： TENG Sheng-bo,LIAO Jian-xin,ZHU Xiao-min state key laboratory of Networking and Switching Technology,beijing University of Posts and Telecommunications,beijing 100876,china state key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876 China

A new load balancing algorithm named dynamic weighed random （DWR） algorithm for the session initiation protocol （SIP） application server cluster is proposed. It uses weighted hashing random algorithm that supports dialog in the SIP protocol to distribute messages. The weight of each server is dynamic adaptive with feedback mechanism. DWR insures that the cluster is balanced, and it performs better than the limited resource vector （LRV） algorithm and minimum sessions first （MSF） algorithm.

关键词： dynamic load balancing weighted random sip application server

Practical conditions of signal space alignment for generalized MIMO Y channel

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Science china(information Sciences) 2012年第10期55卷 2171-2182页

作者： SHE JiaJu 1,2,CHEN ShanZhi 1,2,HU Bo 1,WANG YingMin 2 & SU Xin 2 1 state key laboratory of Networking and Switching Technology,beijing University of Posts and Telecommunications,beijing 100876,china 2 state key laboratory of Wireless Mobile Communications,china Academy of Telecommunications Technology,beijing 100191,china state key laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing China state key laboratory of Wireless Mobile Communications China Academy of Telecommunications Technology Beijing China

This paper proposes a generalization for applications of signal space alignment(SSA) in a generalized multiple input multiple output(MIMO) Y channel with K(K 2) nodes and an intermediate *** on that generalization,a method is introduced to determine the practical conditions for *** first study the generalized MIMO Y channel model with general signal demands;then,the degrees of freedom(DoF) achieved are given and are proved using *** SSA could decrease the number of antennas at the relay,it places new restrictions on the numbers of antennas at the *** then introduce a method to compare the models with and without SSA network coding(SSA-NC),mainly from the perspective of the total number of antennas *** results show that if each node must be able to exchange signals with all others,the model with SSA will definitely use more antennas to supply the same DoF,when K > *** it is not necessary for every node to exchange signals with all others,the comparison can still be made by using the method introduced *** a result,the conditions under which SSA-NC is needed are presented.

关键词： Signal space alignment MIMO Y channel degrees of freedom number of antennas

Insights into correlation between satellite infrared information and fault activities

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Progress in Natural Science:Materials International 2006年第4期16卷 394-402页

作者： MA Jin, WANG Yipeng, CHEN Shunyun, LIU Peixun and LIU Liqiang state key laboratory of Earthquake Dynamics, Institute of Geology, china Earthquake Administration, beijing 100029, china state key laboratory of Earthquake Dynamics Institute of Geology China Earthquake Administration Beijing 100029 China

Tectonic activities are accompanied with material movement and energy transfer, which definitely change the state of thermal radiation on the ground. Thus it is possible to infer present-day tectonic activities based on variations of the thermal radiation state on the ground. The received satellite infrared information is, however, likely influenced by many kinds of factors. Therefore, the first problem that needs to be solved is to extract information on tectonic activities and eliminate effects of external (non-tectonic) factors. In this study, we firstly make a review of the current studies on this subject, and then present the technical approach and our research goal. Using the data of 20 years from the infrared band of the satellite of National Oceanic and Atmospheric Administration (NOAA) and the method we have developed, we investigate fault activities in western china. The results show that the areas with high residual values of land surface brightness temperature (LSBT), which is presumably related to faultings in space, accord usually with the locations of followed major earthquakes. The times of their value growing are also roughly consistent with the beginning of active periods of earthquakes. The low frequency component fields of the LSBT, acquired from wavelet analysis, exhibit well the spatial distributions of active faults. The "heat penetrability index" (HPI) related with enhancement of subsurface thermal information has been expressed well for the backgrounds of accelerated tectonic motions, and some correlations exist between HPI and the local faulting and seismicity. This study provides a new approach to study temporal-spatial evolution of recent activities of faults and their interactions.

关键词： infrared emission fault activity residual of land surface brightness temperature heat penetrability index.

Inconspicuous anchoring effects generated by false information

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Progress in Natural Science:Materials International 2008年第11期18卷 1375-1382页

作者： Chen Qu~(a,b) Jun Wang~a Yuejia Luo~(a,c,*) a state key laboratory of Cognitive Neuroscience and Learning,beijing Normal University,beijing 100875,china b Center for studies of Psychological Application,South china Normal University Guangzhou,510631,china c key laboratory of Mental Health,Institute of Psychology,Chinese Academy of Sciences,beijing 100101,china state key laboratory of Cognitive Neuroscience and Learning Beijing Normal University Beijing 100875 China Center for studies of Psychological Application South China Normal University Guangzhou 510631 China key laboratory of Mental Health Institute of Psychology Chinese Academy of Sciences Beijing 100101 China

The impact of false information on numerical judgments was examined on young normal subjects by an event-related potential(ERP) *** imitate the judgments in real world,we ensured the subjects acknowledged of the target *** behavioral results found that both uncertain information and false information assimilated the final estimates:higher after higher anchors and lower after lower anchors;and false information caused a weaker anchoring bias than uncertain *** results provided further electro- physiological evidence for the mechanism of *** the early phrase,it was an accessibility-dominated process in which two kinds of anchors elicited an N300 component related to the accessibility of anchors *** knowledge relevant to targets joined the process in the late phrase,which caused a larger amplitude of late positive component(LPC)for implausible lower anchors than that for plausible higher *** analysis showed that medial frontal gyrus,whose activity was suggested to signal the need of adjust- ment,was more reliable to explain the LPC elicited by implausible lower ***,we suggest that accessibility is facilitated when the external anchor is consistent with the world knowledge,and adjustment is initiated when the external anchor is inconsistent.

关键词： False anchors Anchoring effects Accessibility Adjustment ERP

Characterization of plastic flow in two Zr-based bulk metallic glasses

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Science china(Technological Sciences) 2006年第4期49卷 414-424页

作者： XING Dongmei1,2, ZHANG Taihua1, LI Weihuo3 & WEI Bingchen3 1. state key laboratory of Nonlinear Mechanics (LNM), Institute of Mechanics, Chinese Academy of Sci- ences, beijing 100080, china 2. College of Physics and Electronic information Science, Tianjin Normal University, Tianjin 300074, china 3. National Microgravity laboratory, Institute of Mechanics, Chinese Academy of Sciences, beijing 100080, china state key laboratory of Nonlinear Mechanics (LNM) Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China sychology.lu.se

Plastic deformation behaviors of Zr65Al10Ni10Cu15 and Zr52.5Al10Ni10Cu15Be12.5 bulk metallic glasses (BMGs) are studied by using the depth-sensing nanoindentation, microindentation and uniaxial compression. The Be-containing BMG exhibits a signifi- cantly improved overall plastic strain compared with the Be-free alloy during compressive tests. Both BMGs show a loading-rate-dependent serrated flow during nanoindentation measurements, but the Be-containing alloy exhibits a much lower critical loading rate for the disappearance of the serration than the Be-free BMG. The shear band patterns de- veloped during plastic deformation are investigated by microindentation technique, wherein much higher shear band density is found in the Be-containing alloy than in the Be-free alloy, indicating an easier nucleation of shear bands in the former BMG. The dif- ference in the plastic deformation behavior of the two BMGs can be explained by a free volume model.

关键词： Bulk metallic glass, plastic deformation, shear band, nanoindentation.

Possible mechanism of the effect of convection over Asian-Australian “land bridge” on the East Asian summer monsoon onset

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Science china Earth Sciences 2006年第11期49卷 1223-1232页

作者： HE Jinhai1, WEN Min2, DING Yihui3 & ZHANG Renhe2 1. Jiangsu key laboratory of Meteorological Disaster (KLME), Nanjing Institute of Meteorology, Nanjing University of Informa- tion Science and Technology, Nanjing 210044, china 2. state key laboratory of Severe Weather (LaSW), Chinese Academy of Meteorological Sciences, beijing 100081, china 3. National Climate Center, Chinese Meteorological Administration, beijing 100081, china Jiangsu key laboratory of Meteorological Disaster (KLME) Nanjing Institute of Meteorology Nanjing University of Information Science and Technology Nanjing China state key laboratory of Severe Weather (LaSW) Chinese Academy of Meteorological Sciences Beijing China National Climate Center Chinese Meteorological Administration Beijing China

The Asian-Australian “land bridge” is an area with the most vigorous convection in Asian monsoon region in boreal spring, where the onset and march of convection are well associated with the onset of East Asian summer monsoon. The convection occurs over Indo-china Peninsula as early as mid-April, which exerts critical impact on the evolution of monsoon circulation. Before mid-April there are primarily sensible heatings to the atmosphere over Indo-china Peninsula and Indian Peninsula, so the apparent heating ratios over them decrease with height. However, after mid-April it changes into latent heating over Indo-china Peninsula due to the onset of convection, and the apparent heating ratio increases with height in mid- and lower troposphere. The vertical distribution of heating ratio and its differences between Indo-china Peninsula and Indian Peninsula are the key factors leading to the splitting of boreal subtropical high belt over the Bay of Bengal. Such mechanism is strongly supported by the fact that the evolution of the vertical heating ratio gradient above Indo-china Peninsula leads that of 850 hPa vorticity over the Bay of Bengal. Convections over Indo-china Peninsula and its surrounding areas further increase after the splitting. Since then, there is a positive feedback lying among the convective heating, the eastward retreat of the subtropical high and the march of monsoon, which is a possible mechanism of the advance of summer monsoon and convection from Indo-china Peninsula to South china Sea.

关键词： Asian-Australian 'land bridge', tropical convection, Indo-china Peninsula, the splitting of boreal subtropical high belt, East Asian summer monsoon onset.

Polar differential power attacks and evaluation

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Science china(information Sciences) 2012年第7期55卷 1588-1604页

作者： TANG Ming 1 ,QIU ZhenLong 1 ,GAO Si 1,2 ,YI Mu 3 ,LIU ShuBo 1 ,ZHANG HuanGuo 1 & JIN YingZhen 1 1 School of Computer Science,Wuhan University,Wuhan 430072,china 2 state key laboratory of information security,Institute of Software,Chinese Academy of Sciences,beijing 100190,china 3 Centre for Computer and information security Research School of Computer Science and Software Engineering University of Wollongong,Wollongong,NSW 2522,Australia School of Computer Science Wuhan University Wuhan China state key laboratory of information security Institute of Software Chinese Academy of Sciences Beijing China Centre for Computer and information security Research School of Computer Science and Software Engineering University of Wollongong Wollongong Australia

Side channel attacks (SCAs) on security software and hardware have become major concerns on computer and system *** existing SCAs generally require the knowledge of the corresponding cryptographic algorithm and implementation adopted in the target; therefore,they are not fully suitable for practical *** this paper,we propose a novel SCA-polar differential power attack (polar DPA).We found that DPA peaks have different biases for different cryptographic algorithms and *** on these biases,we can successfully attack a block cipher,assuming that the cipher algorithm uses a secret key in its first round,without the knowledge of the cipher algorithm or *** rounds can be treated as a black *** present a detailed theoretical analysis and experiment to demonstrate the correctness and efficiency of our ***,our scheme has demonstrated an improvement over the leakage evaluation scheme due to Ichikawa et al.(CHES 2005).Our evaluation method can be used in electronic design automatic (EDA) flows and can help security circuit designers to understand the data leakage due to SCAs.

关键词： computer security differential power attack side channel attack