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A Linearly-Polarized Cesium Vapor Laser with Fundamental Mode Output and Low Threshold

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Chinese Physics Letters 2014年第4期31卷 57-59页

作者： LI Zhi-Yong TAN Rong-Qing HUANG Wei XU Cheng Department of High Power Gas Laser Institute of Electronics Chinese Academy of Sciences Beijing 100190 Graduate University of Chinese Academy of Sciences Beijing 100049 Beijing Institute of Aerospace Control Devices Beijing 100854 Quantum Engineering Research Center China Aerospace Science and Technology Corporation Beijing 100854

We report a cesium vapor laser with fundamental mode output and a wavelength of 894 nm. The laser is pumped by a laser diode array with an external cavity of a holographic grating by using Littrow＇s structure. A slope efbciency of 22.4% is obtained by using a pumping source with a linewidth of 0.26 nm and 80 kPa methane as the buffer gas. The threshold pumping power is 1.56 W.

关键词： Threshold A Linearly-Polarized buffer

Timings of early crustal activity in southern highlands of Mars:Periods of crustal stretching and shortening

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Geoscience Frontiers 2019年第3期10卷 1029-1037页

作者： Trishit Ruj Goro Komatsu Jan Hendrik Pasckert James M.Dohm International Research School of Planetary Sciences Università d'Annunzio Department of Earth and Planetary Science School of Science University of Tokyo Institut für Planetologie Westf?lische Wilhelms-Universit?t Foundation for Advancement of International Science

Extensional and compressional structures are globally abundant on Mars. Distribution of these structures and their ages constrain the crustal stress state and tectonic evolution of the planet. Here in this paper, we report on our investigation over the distribution of the tectonic structures and timings of the associated stress fields from the Noachis-Sabaea region. Thereafter, we hypothesize possible origins in relation to the internal/external processes through detailed morphostructural mapping. In doing so, we have extracted the absolute model ages of these linear tectonic structures using crater size-frequency distribution measurements, buffered crater counting in particular. The estimated ages indicate that the tectonic structures are younger than the mega impacts events(especially Hellas) and instead they reveal two dominant phases of interior dynamics prevailing on the southern highlands, firstly the extensional phase terminating around3.8 Ga forming grabens and then compressional phase around 3.5-3.6 Ga producing wrinkle ridges and lobate scarps. These derived absolute model ages of the grabens exhibit the age ca. 100 Ma younger than the previously documented end of the global extensional phase. The following compressional activity corresponds to the peak of global contraction period in Early Hesperian. Therefore, we conclude that the planet wide heat loss mechanism, involving crustal stretching coupled with gravitationally driven relaxation(i.e.,lithospheric mobility) resulted in the extensional structures around Late Noachian(around 3.8 Ga). Lately cooling related global contraction generated compressional stress ensuing shortening of the upper crust of the southern highlands at the Early Hesperian period(around 3.5-3.6 Ga).

关键词： Martian dynamics Southern highlands Extensional tectonics Compressional tectonics Age of structures buffer crater counting

USE　OF　CONJUGATED　SALT　PAIR　TO　buffer　OPTIMAL　pH　LEVEL　DURING　LIPASE－CATALYZED　SYNTHESIS　IN　ORGANIC　SOLVENTS

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Chinese Chemical Letters 1994年第3期5卷 199-200页

作者： Min Qin LI Hui Xian XU Bing Lin HE(Institute of Polymer Chemistry, Nankai University, Tianjin 300071)

Enzyme catalyzed esterifcation in organic solvent system depends highly oh conjugated salt pair at different PH. We ha,e shown that the addition of an appropriate sol id conjugated salt pair to the esterification rect... 详细信息

关键词： pH OPTIMAL LEVEL DURING LIPASE buffer CATALYZED

Energy efficient fuzzy-based DASH adaptation algorithm

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Digital Communications and Networks 2021年第1期7卷 113-119页

作者： Moad Mowafi Eyad Taqieddin Hiba Al-Dahoud Department of Network Engineering and Security Jordan University of Science and TechnologyIrbid22110Jordan

With the expansive demand for video streaming over mobile networks,it is necessary to adopt schemes that balance the need for high video quality with the available network resources when streaming or downloading the video.Several approaches were proposed in the literature,including Dynamic Adaptive Streaming over HTTP(DASH).In this work,we consider an approach in which we place sufficient emphasis on the constrained battery resources in mobile devices when making decisions on the quality(or bitrate)of the video to be requested.This is done by using a fuzzy logic controller that enhances the performance of the Fuzzy-based DASH(FDASH)scheme.Simulation results show that our proposed approach conserves more energy than its predecessor while maintaining similar video quality and avoiding playback interruptions.

关键词： DASH Bitrate adaptation Energy Throughput buffer

Evaluating the effect of dislocation on the photovoltaic performance of metamorphic tandem solar cells

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中国科学：技术科学英文版 2010年第9期53卷 2569-2574页

作者： ZHANG Han1,CHEN NuoFu2,3,WANG Yu1,ZHANG XingWang1,YIN ZhiGang1,SHI HuiWei1,WANG YanSuo1,HUANG TianMao1,BAI YiMing2 & FU Zhen11 Key Laboratory of Semiconductor Materials Science,Institute of Semiconductors,Chinese Academy of Sciences,P.O.Box 912,Beijing 100083,China 2 School of Renewable Energy Engineering,North China Electric Power University,Beijing 102206,China 3 State Key Laboratory of Silicon Materials,Zhejiang University,Hangzhou 310027,China Key Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences Beijing China School of Renewable Energy Engineering North China Electric Power University Beijing China State Key Laboratory of Silicon Materials Zhejiang University Hangzhou China

The photovoltaic conversion efficiency for monolithic GaInP/GaInAs/Ge triple-junction cell with various bandgap combination (300 suns,AM1.5d) was theoretically calculated.An impressive improvement on conversion efficiency was observed for a bandgap combination of 1.708,1.194,and 0.67 eV.A theoretical investigation was carried out on the effect of dislocation on the metamorphic structure’s efficiency by regarding dislocation as minority-carrier recombination center.The results showed that only when dislocation density was less than 1.6×106 cm-2,can this metamorphic combination exhibit its efficiency advantage over the fully-matched combination.In addition,we also briefly evaluated the lattice misfit dependence of the dislocation density for a group of metamorphic triple-junction system,and used it as guidance for the choice of the proper cell structure.

关键词： tandem solar cell theoretical efficiency dislocation buffer layers

Effects of growth temperature and metamorphic buffer on electron mobility of InAs film grown on Si substrate by molecular beam epitaxy

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Chinese Physics B 2019年第2期28卷 428-433页

作者：张静吕红亮倪海桥杨施政崔晓然牛智川张义门张玉明 School of Microelectronics Xidian University and the State Key Discipline Laboratory of Wide Band Gap Semiconductor Technology State Key Laboratory for Superlattices and Microstructures Institute of Semiconductors Chinese Academy of Sciences

The growth of the InAs film directly on the Si substrate deflected from the plane(100) at 4° towards(110) has been performed using a two-step procedure. The effect of the growth and annealing temperature on the electron mobility and surface topography has been investigated for a set of samples. The results show that the highest electron mobility is4640 cm^2/V·s in the sample, in which the 10-nm InAs nucleation layer is grown at a low temperature of 320 ℃ followed by ramping up to 560 ℃, and the nucleation layer was annealed for 15 min and the second layer of InAs is grown at 520 ℃.The influence of different buffer layers on the electron mobility of the samples has also been investigated, which shows that the highest electron mobility of 9222 cm^2/V·s at 300 K is obtained in the sample grown on a thick and linearly graded InGaAlAs metamorphic buffer layer deposited at 420 ℃.

关键词： InAs Si high electron mobility growth temperature InGaAlAs metamorphic buffer

Traffic dynamics considering packet loss in finite buffer networks

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Chinese Physics B 2019年第4期28卷 433-438页

作者：陈杰陈金邕李明胡茂彬 School of Engineering Science University of Science and Technology of China Civil Architectural and Environmental Engineering University of Texas at Austin

In real complex systems, the limited storage capacity of physical devices often results in the loss of data. We study the effect of buffer size on packet loss threshold in scale-free networks. A new order parameter is proposed to characterize the packet loss threshold. Our results show that the packet loss threshold can be optimized with a relative small buffer size. Meanwhile, a large buffer size will increase the travel time. Furthermore, we propose a buffered-Shortest-Path-First(BSPF) queuing strategy. Compared to the traditional First-In-First-Out(FIFO) strategy, BSPF can not only increase the packet loss threshold but can also significantly decrease the travel length and travel time in both identical and heterogeneous node capacity cases. Our study will help to improve the traffic performance in finite buffer networks.

关键词： finite buffer networks loss threshold queuing strategy

Parameter Optimization of Nose Landing Gear Considering Both Take-off and Landing Performance of Catapult Take-off Carrier-Based Aircraft

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第2期33卷 187-198页

作者： Zhang Ming Nie Hong He Zhihang Key Laboratory of Fundamental Science for National Defense-Advanced Design Technology of Flight Vehicle Nanjing University of Aeronautics and Astronautics State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and Astronautics

Optimization of the parameters of landing gear systems with double-stage air springs of catapult take-off carrier-based aircraft is here studied based on the mathematical equations of the classic dual mass spring-damper dynamic model.Certain standards for both take-off and landing performance are put forward.The contradictory factors between take-off and landing processes are analyzed.The optimization of oil in the pin area and the area near the rear oil hole is performed.Then these optimized parameters are used to assess the influence of the initial pressure of the low chamber,the ratio of the high chamber to the low chamber,and the tire inflation pressure on the performance of arresting landing and catapult take-off.The influences of these parameters on carrier-based aircraft and the aircraft-carrier on aircraft catapult take-off is also assessed.Based on the results of the simulation,respective take-off criteria must be drafted considering different types of aircraft and different take-off load cases,all of which must be matched to parameters relevant to catapult take-off.

关键词： carrier-based aircraft buffer performance fast-extension performance aircraft design optimization sensitivity analysis

Spatial Analysis for Determining Accessibility to Bus Stops in Kaduna Metropolis

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Journal of Geographic Information System 2022年第1期14卷 78-93页

作者： Paul Itomi-Ushi Daudu Mamman Saba Jibril Jennifer Yashi Nigerian Building and Road Research Institute Abuja Nigeria Nigerian Defence Academy Kaduna Nigeria

Bus stop accessibility is a vital component of a successful transportation system. This study aimed at spatially analyzing bus stops to determine their physical accessibility considering the connecting roads surrounding the bus stops. This research used satellite imagery, Global Navigation Satellite System and Kaduna State Traffic and Environment Law Enforcement Authority documents. The spatial analysis covered bus stop accessibility and obtained data of transport routes, bus stop coordinates, bus stop spacing and physical characteristics of bus stops. GIS buffer, network and area analysis was used in measuring bus stop accessibility considering the road network surrounding it. The ratio of ideal access coverage to the actual access coverage of a stop was calculated. Paired sample statistics were used to compare ideal and actual access coverage;the finding revealed a significant difference between the ideal and actual access coverage. A range of 0 - 1.0 was used in the analysis where, a bus stop is less accessible the closer the value is to 0, and more accessible the closer the value is to 1.0. Linear regression statistics was used to determine if the level of accessibility of a bus stop is dependent on the length of roads within the buffer. This revealed that at R = 0.694, a strong degree of correlation exists between the level of accessibility and road length within the buffer. The study concluded that before siting bus stops, surrounding road networks need to be considered in order to make them accessible.

关键词： Accessibility buffer Network Analysis Ideal Access Coverage Actual Access Coverage