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Orthogonally linear polarized lasers (I)——principle and devices

Progress in Natural science:Materials International 2005年第7期15卷 586-595页

作者： ZHANG Shulian and XU Ting (State Key laboratory of Precision Measurement technology and Instruments, Department of Precision Instruments, Tsinghua University, beijing 100084, china) State Key laboratory of Precision Measurement technology and Instruments Department of Precision Instruments Tsinghua University Beijing 100084 China

Two kinds of orthogonally polarized lasers, i. e. Zeeman dual-frequency lasers and four-frequency ring lasers (laser gyros) have been developed since the invention of lasers, in which circularly polarized lights oscillate. This paper summarizes recent progress of the study on orthogonally linear polarized lasers with the standing wave cavity. Firstly, the expression of producing orthogonally linear polarized lights in standing wave cavity, i. e. laser frequency splitting, is given. Almost all the birefringence effects made in laser cavity are used to produce orthogonally linear polarized lights. The effect includes quartz crystal birefringence effect, calcite birefringence effect, stress (photo-elastic) birefringence effect and electro-optical birefringence effect. Secondly, several physical phenomena of orthogonally linear polarized lasers are discovered such as aberrance of frequency splitting curves caused by optical activity of quartz crystal, order-passing of longitudinal modes with frequency splitting and strong modes competition. Finally, because the traditional Zeeman dual frequency laser cannot output frequency difference larger than 3 MHz, the approaches of obtaining larger frequency difference are studied. The sequential results, several kinds of orthogonally polarized lasers, are described, such as birefringence dual frequency lasers outputting a frequency difference from 40 MHz to hundreds of megahertz, birefringence-Zeeman dual frequency lasers outputting a frequency difference from 1 MHz to hundreds of megahertz, the LD pumped YAG birefringence dual frequency laser outputting frequency difference of several gigahertz, and the lasers whose longitudinal mode spacing is c/4L instead of c/2L .

关键词： orthogonally polarized laser dual frequency laser intra-cavity birefringence Zeeman effect photo-elastic birefringence electro-optical birefringence frequency splitting.

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Mathematical Delineation of the Thermophysical Process of Electron Beam Welding

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稀有金属材料与工程 2011年第S4期40卷 134-137页

作者： Wang Xuedong1,2,Fu Pengfei 1,Shi Qingyu 2 1national Key laboratory of science and technology on Power Beam Processes,beijing Aeronautical Manufacturing Research Institute,beijing 100024,china2 Department of Mechanical Engineering,Tsinghua University,beijing 100084,china beijing Aeronaut Mfg Res Inst Natl Key Lab Sci & Technol Power Beam Proc Beijing 100024 Peoples R China Tsinghua Univ Dept Mech Engn Beijing 100084 Peoples R China

Multiple factors and complicated coupling relationships exist in the weldment during EBW,in order to comprehend this process,a mathematical delineation method based on a main line was presented in this *** on the main line,the complicated coupling relationships existing in EBW were reproduced by mathematical *** calculational results were in well agreement with the experimental *** mathematical delineation was an effective method to comprehend the features and essence of EBW.

关键词： electron beam welding mass transfer identification of phase interface keyhole

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Full-scale experimental research on fire fume refluence of sloped long and large curved tunnel

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science china(Technological sciences) 2011年第S1期54卷 89-94页

作者： ZHONG MaoHua 1,SHI CongLing 1,HE Li 1,SHI JieHong 1 & FU TaiRan 2 1 china Academy of Safety science and technology,beijing 100012,china 2 Key laboratory for Thermal science and Power Engineering of Ministry of Education,Department of Thermal Engineering,Tsinghua University,beijing 100084,china 1. china Academy of Safety science and technology Beijing 100012 China 2. Key laboratory for Thermal science and Power Engineering of Ministry of Education Department of Thermal Engineering Tsinghua University Beijing 100084 China

A full-scale experimental research is conducted on the fire fume refluence of a sloped long and large curved tunnel in the underground plant of a hydraulic and hydropower engineering project under three different fire *** a result,the eddy effect and pattern of the fire fume flow in the tunnel in case of fire is discovered and the refluence of the fume layers in case of fire is *** analysis of the temperature measurement resulted in the course of the experiment,the main characteristics and performance of the fire fume refluence are discussed under the three different fire powers.

关键词： large and long tunnel fire fume refluence experiment

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Nitrogen removal via nitrite from municipal landfill leachate

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Journal of Environmental sciences 2009年第11期21卷 1480-1485页

作者： WU Lina, PENG Chengyao, ZHANG Shujun, PENG Yongzhen Key laboratory of beijing for Water Quality science and Water Environment Recovery Engineering, beijing University of technology, beijing 100124, china. [a]Key laboratory of beijing for Water Quality science and Water Environment Recovery Engineering Beijing University of Technology Beijing 100124 China

A system consisting of a two-stage up-flow anaerobic sludge blanket （UASB）, an anoxic/aerobic （A/O） reactor and a sequencing batch reactor （SBR）, was used to treat landfill leachate. During operation, denitrification and methanogenesis took place simultaneously in the first stage UASB, and the effluent chemical oxygen demand （COD） was further removed in the second stage UASB. Then the denitrification of nitrite and nitrate in the returned sludge by using the residual COD was accomplished in the A/O reactor, and ammonia was removed via nitrite in it. Last but not least, the residual ammonia was removed in SBR as well as nitrite and nitrate which were produced by nitrification. The results over 120 d （60 d for phase I and 60 d for phase II） were as follows： when the total nitrogen （TN） concentration of influent leachate was about 2500 mg/L and the ammonia nitrogen concentration was about 2000 mg/L, the shortcut nitrification with 85%-90% nitrite accumulation was achieved stably in the A/O reactor. The TN and ammonia nitrogen removal efficiencies of the system were 98% and 97%, respectively. The residual ammonia, nitrite and nitrate produced during nitrification in the A/O reactor could be washed out almost completely in SBR. The TN and ammonia nitrogen concentrations of final effluent were about 39 mg/L and 12 mg/L, respectively.

关键词： short-cut nitrification up-flow anaerobic sludge blanket anoxic/aerobic reactor sequencing batch reactor landfill leachate

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Optimizing write operation on replica in data grid

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science china(information sciences) 2011年第1期54卷 1-11页

作者： XU PengZhi,WU YongWei,HUANG XiaoMeng, YANG GuangWen & ZHENG WeiMin Department of Computer science and technology,Tsinghua University,beijing 100084,china 1. Department of Computer science and technology Tsinghua University Beijing 100084 China

Replication technique can improve access performance and data availability of data grid systems. So far,most related work on data replication in data grid systems focuses on read-only *** write operations have been widely used in practice,its optimization problem has not been suciently *** this paper,we show that write requests from users can be processed by a nearest site,regardless of the location of latest written *** policy of write nearby instead of write to the latest replica can improve the performance of write operations,while inconsistency is caused between multiple ***,we propose two metadata management algorithms to make sure that users can retrieve up-to-date datasets at any *** extend OptorSim to support the implementation and evaluation of our *** results of simulation show that our scheme achieves performance gains up to 3.3 compared with WriteMaster scheme.

关键词： replication data grid simulation access latency

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Kinetic characteristics of continuous flow polymerase chain reaction chip: A numerical investigation

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science china(Technological sciences) 2010年第7期53卷 1967-1972页

作者： WANG ShiYing1 & WANG Wei2,3 1 School of Physics, Peking University, beijing 100871, china 2 Institute of Microelectronics, Peking University, beijing 100871, china 3 national Key laboratory of science and technology on Micro/Nano Fabrication, beijing 100871, china 1. School of Physics Peking University Beijing 100871 China2. Institute of Microelectronics Peking University Beijing 100871 China3. National Key Laboratory of Science and Technology on Micro/Nano Fabrication Beijing 100871 China

Continuous flow PCR (polymerase chain reaction) chip holds impressive advantages compared to micro chamber PCR chip. In order to have better understanding of kinetic characteristics of continuous flow PCR chip, a comprehensive mathematical model is presented in this paper, including melting, annealing and extension phases of a typical PCR process which has the essence of a convection-diffusion-reaction system. Using this model, we can simulate the PCR process in series of reaction cycles. Numerical results show that the average sample velocity plays a significant role in affecting the amplification efficiency. Also, appropriate combination of the PCR mixture is important for high-quality DNA amplification. Giving a large initial DNA concentration range, the continuous flow PCR scheme holds excellent real-time detection ability theoretically. The present numerical model bridges the temperature distribution to the real DNA amplification, and thereby is able to successfully predict continuous flow PCR properties which are important for the chip design.

关键词： continuous flow PCR chip numerical simulation convection-diffusion-reaction system

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Competent predicate abstraction in model checking

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science china(information sciences) 2011年第2期54卷 258-267页

作者： LI Li1,2,3, SONG XiaoYu4, GU Ming2,3 & LUO XiangYu2,3 1Department of Computer science & technology, Tsinghua University, beijing 100084, china 2Key laboratory for information System Security, Ministry of Education of china, beijing 100084, china 3School of Software, Tsinghua University, beijing 100084, china 4Department of ECE, Portland State University, Portland, Oregon 97207, USA 1. Department of Computer science & technology Tsinghua University Beijing 100084 China2. Key Laboratory for Information System Security Ministry of Education of China Beijing 100084 China3. School of Software Tsinghua University Beijing 100084 China4. Department of ECE Portland State University Portland Oregon 97207 USA

The paper presents a new approach to computing the abstract state and a maximum weight heuristic method for finding the shortest counter-example in verification of imperative programs. The strategy is incorporated in a verification system based on the counterexample-guided abstraction refinement method. The proposed method slashes both the size of the abstract state space and the number of invokes of a decision procedure. A number of benchmarks are employed to evaluate the effectiveness of the approach.

关键词： program model checking predicate abstraction weight heuristic

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Density functional theory study of the reaction paths of reactions of CH3C（O）O2 radicals with HO2 in the gas phase

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Progress in Natural science:Materials International 2006年第12期16卷 1269-1274页

作者： ZHOU Yuzhi~ 1,2 , ZHANG Shaowen~1 and LI Qianshu~1**(1. State Key laboratory of Explosion science and technology, beijing Institute of technology, beijing 100081, china 2. beijing Institute of Education, beijing 100044, china) [a]State Key laboratory of Explosion science and technology Beijing Institute of Technology Beijing China [b]beijing Institute of Education Beijing China

A DFT study on the reactions between CH_3C（O）O_2and HO_2radicals has been carried out. It is suggested that both the triplet and singlet potential surfaces involve a complex mechanism with the formation of loosely bound intermediate complexes of reactants and products. The reaction prefers to occur on the triplet surface to produce peracetic acid (CH_3C（O）O_2H) and triplet O_2molecule. The CH_3C（O）O_2H can further convert into CH_3C（O）O and HO radicals.

关键词： acetyl peroxy radicals HO2 radicals reaction mechanism DFT.

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Cloning and characterization of cotton heteromeric acetyl-CoA carboxylase genes

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Progress in Natural science:Materials International 2007年第12期17卷 1412-1418页

作者： Qiao Zhixin and Liu Jinyuan(laboratory of Molecular Biology and Protein science laboratory of the Ministry of Education, Department of Biological sciences and Biotechnology, Tsinghua University, beijing 100084, china) laboratory of Molecular Biology and Protein science laboratory of the Ministry of Education Department of Biological Sciences and Biotechnology Tsinghua University Beijing 100084 China

Heteromeric acetyl-coenzyme A (CoA) carboxylase (ACCase) catalyzes the formation of malonyl-CoA from acetyl-CoA. It plays an essential role in fatty acid synthesis in prokaryotes and most of plants. The heteromeric ACCase is composed of four subunits: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and α- and β-subunits of carboxyltransferase (α- and β-CT). In this study, we cloned five novel genes encoding the subunits of heteromeric ACCase (one BC, BCCP and β-CT, and two α-CTs) from cotton (Gossypium hirsutum cv. zhongmian 35) by RACE-PCR. The deduced amino acid sequence of these cDNAs shares high similarity with other reported heteromeric ACCase subunits. The phylogenetic analysis indicated that the different subunits of heteromeric ACCase were grouped in a similar pattern. Southern blot analysis revealed the milti-copy patterns of these heteromeric ACCase genes in cotton genome. Semi-quantitative RT-PCR demonstrated that heteromeric ACCase genes were constitutively expressed in all of the cotton tissues, but the transcripts accumulated at a relatively low level in roots. To our knowledge, this is the first report about characterization of the heteromeric ACCase genes in cotton.

关键词： heteromeric ACCase cotton gene cloning fatty acid synthesis.

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Robust AVS audio watermarking

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science china(information sciences) 2010年第3期53卷 607-618页

作者： WANG Yong & HUANG JiWu Guangdong Key laboratory of information Security technology, School of information science and technology, Sun Yat-Sen University, Guangzhou 510275, china 1. Guangdong Key laboratory of information Security technology School of Information Science and Technology Sun Yat-Sen University Guangzhou 510275 China

Part Ⅲ of AVS (china Audio and Video Coding Standard) is the first generic audio standard proposed in china and is becoming popular in some applications. For MP3 audio, some effiorts have been made to solve the copyright pirating and malicious modifications by the way of watermarking. To our best knowledge, similar work on the AVS audio has not been explored. In this paper, we present a novel robust watermarking algorithm for AVS audio. We find that the frame type in the AVS coded process can be used as a robust feature for watermarking. Then we design a novel watermarking algorithm which is integrated into the AVS audio coding process. The watermark bits are embedded into the compressed bit stream. At the extracting end, the watermark bits can be extracted from the compressed bit stream directly. This algorithm achieves robustness to decoding/re-coding attacks, and has low computation complexity for both embedding and extracting while preserving the quality of the audio signals.

关键词： AVS audio security problems robust watermarking

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