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Simulation and experiments on cooling and power system driven a solid sorption combined by the exhaust waste heat

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Frontiers in Energy 2017年第4期11卷 516-526页

作者： Peng GAO Liwei WANG Ruzhu WANG Yang yu Institute of Refrigeration and Cryogenics Shanghai Jiao Tong University Shanghai 200240 China

A solid sorption combined cooling and power system driven by exhaust waste heat is proposed, which consists of a MnCl2 sorption bed, a CaCl2 sorption bed, an evaporator, a condenser, an expansion valve, and a scroll expander, and ammonia is chosen as the working fluid. First, the theoretical model of the system is established, and the partitioning calculation method is proposed for sorption beds. Next, the experimental system is estab- lished, and experimental results show that the refrigerating capacity at the refrigerating temperature of-10℃ and the resorption time of 30 min is 1.95 kW, and the shaft power is 109.2 W. The system can provide approximately 60% of the power for the evaporator fan and the condenser fan. Finally, the performance of the system is compared with that of the solid sorption refrigeration system. The refrigerating capacity of two systems is almost the same at the same operational condition. Therefore, the power generation process does not influence the refrigeration process. The exergy efficiency of the two systems is 0.076 and 0.047, respectively. The feasibility of the system is determined, which proves that this system is especially suitable for the exhaust waste heat recovery.

关键词： solid sorption exhaust waste heat combinedcooling and power system exergy efficiency

Correlation between brazed joint elevated strength,microstructure and brazing processing parameter of Inconel superalloy

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Acta Metallurgica Sinica(English Letters) 2011年第3期24卷 205-212页

作者： Chunwei MA Kun SHI Zhishui yu Peiquan XU Department of Materials Engineering Shanghai University of Engineering Science Shanghai 201620 China

This study investigates the influences of brazing temperature, brazing time and braz- ing clearance on microstructures and high temperature strength of Inconel superalloy. Bonding is performed in a high vacuum furnace using BNi-2 as filler metal. Brazing temperatures employed in this study are 1080 ℃, 1110 ℃ and 1140 ℃. Holding times at the brazing temperature are 5 min, 15 min and 45 min. At the same time, the investigated brazing clearances are 30μm, 60 μm and 100 pro. Microstructure of the brazed joints is analyzed by means of metallography, scanning electron microscope （SEM）. The high temperature tensile strength and microhardness are evaluated at different brazing parameters. The results show that fracture occurs wholly within the braze metal. Deformation appears to be confined to the braze metal with the base metal, showing very little plastic deformation. Brazing time shows to play the important role in the brazing parameters. The peak of microhardness is at the centerline of braze region. Induction heating has little effect on the base materials.

关键词： Vacuum brazing Inconel superalloy Brazing parameter Microstructure High temperature strength Microhardness

How the Salesmanship and Brainpower Failed at Long-Term Capital Shulang Chen/Jasmine yu

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英语学习 1999年第3期 33-36页

作者： Jasmine yu

金融权威败走麦城——两位诺贝尔经济学奖得主所经营的基金是如何失败的编注:纽约华尔街汇聚了世界各国知名的金融机构和成交量占世界首位的纽约股票交易所,是美国和世界的金融中心。1998年9月24日,华尔街爆出了重大新闻:由美国中央银... 详细信息

金融权威败走麦城——两位诺贝尔经济学奖得主所经营的基金是如何失败的编注:纽约华尔街汇聚了世界各国知名的金融机构和成交量占世界首位的纽约股票交易所,是美国和世界的金融中心。1998年9月24日,华尔街爆出了重大新闻:由美国中央银行——美国联邦储备委员会牵头,14家华尔街著名国际投资银行和商业银行提供36亿美元贷款,拯球濒临破产的长期资本管理公司(Long-Term Capital)。此后近一个月,长期资本管理公司经济援助事件受到美国和国际经济新闻媒体的广泛关注。长期资本管理公司是一家

关键词：所罗门费尔德到期日瑞士联合银行 How the Salesmanship and Brainpower Failed at Long-Term Capital Shulang Chen/Jasmine yu 对冲基金长期资本国库券

Pricing Credit Spread Option with Longstaff-Schwartz and GARCH Models in Chinese Bond Market

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Journal of Systems Science & Complexity 2015年第6期28卷 1363-1373页

作者： ZHOU Rongxi DU Sinan yu Mei YANG Fengmei School of Economics and Management Beijing University of Chemical Technology Research Center for Applied Finance School of Finance and Banking University of International Business and Economics School of Science Beijing University of Chemical Technology

This paper investigates the mean-reversion and volatile of credit spread time series by using regression and time series analysis in Chinese bond market. Then the Longstaff-Schwartz model and GARCH model are applied to price credit spread put option. The authors compare the features of these two models by employing daily bond prices of government bonds and corporate bonds for the period 2010–2012 in Chinese bond market. The proposed results show that the higher the credit ratings of the corporate bonds are, the lower the prices of the credit spread options are.

关键词： Credit spread option Longstaff-Schwartz model GARCH model pricing

Ionic liquid coated single-walled carbon nanotube buckypaper as supercapacitor electrode

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Particuology 2013年第4期11卷 409-414页

作者： Chao Zheng Weizhong Qian yuntao yu Fei Wei Beijing Key Laboratory of Green Reaction Engineering & Technology Department of Chemical EngineeringTsinghua University

Effect of stacking structure of single-walled carbon nanotubes （SWCNTs） on its performance as electrode of supercapacitor was investigated in the present work. Considering SWCNTs easily formed bundles due to strong van de Waals attraction between tubes, we proposed first dispersion of SWCNTs by ionic liquids （ILs） of 1 -ethyl-3-methyl imidazolium tetrafluoroborate （EMIMBF4）, followed by fabrication of buckypa- per by compression. The debundling effect of ILs on SWCNTs increased the interface between electrode and electrolyte, decreased electrical resistance, and, consequently, increased performance of the superca- pacitor. Since ILs, used to disperse SWCNTs, also functioned as electrolyte in supercapacitor, our method is a simple way to prepare buckypaper electrode with high performance.

关键词： Carbon nanotubesBuckypaperSupercapacitorlonicliquids

A USM-Θ two-phase turbulence model for simulating dense gas-particle flows

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Acta Mechanica Sinica 2005年第3期21卷 228-234页

作者： Yong yu Lixing Zhou Baoguo Wang Feipeng Cai Department of Engineering Mechanics Tsinghua University Beijing 100084 China School of Mechanico-Electrical Engineering Beijing Institute of Technology Beijing 100081 China Institute of Chemical Engineering University of Petroleum Beijing 102249 China

A second-order moment two-phase turbulence model for simulating dense gas-particle flows （USM-Θ model）, combining the unified second-order moment twophase turbulence model for dilute gas-particle flows with the kinetic theory of particle collision, is proposed. The interaction between gas and particle turbulence is simulated using the transport equation of two-phase velocity correlation with a two-time-scale dissipation closure. The proposed model is applied to simulate dense gas-particle flows in a horizontal channel and a downer. Simulation results and their comparison with experimental results show that the model accounting for both anisotropic particle turbulence and particle-particle collision is obviously better than models accounting for only particle turbulence or only particle-particle collision. The USM-Θ model is also better than the k-ε-kp-Θ model and the k-ε-kp-εp-Θ model in that the first model can simulate the redistribution of anisotropic particle Reynolds stress components due to inter-particle collision, whereas the second and third models cannot.

关键词： Turbulence Two-phase flow Second-ordermoment model

Experiments on and predictions about properties of sand bonded by microbe cement

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Science China(Technological Sciences) 2016年第8期59卷 1186-1193页

作者： QIAN ChunXiang RONG Hui yu XiaoNiu WANG Xin School of Materials Science and Engineering Southeast University Nanjing 211189 China Research Institute of Green Construction Materials Southeast University Nanjing 211189 China

Microbe cement as a new bonding material is presented. Sandstone （0.05 m diameter, 0.5 m height） and sandpile （0.125 m^3） are joined by microbe cement to make a whole body. Evolutions in the related properties of treated sand samples are examined through compressive strength and calcite content. Results indicate that the structure of the cemented body is nonuniform, that the calcite content decreases with distance from the injection port, and that the compressive strength also decreases with dis- tance from the injection port. In addition, evolutions in the measured calcite content and compressive strength are summarized by a numerical model that considers microbe concentration distribution. The numerical results of the calcite content at different positions for 0.5 m height sandstone are similar to the test results, and the experimental results for calcite content and compres- sive strength of 0.125 m^3 cubic sandpile are similar to the numerical results. Prediction results indicate that the simulations should become a significant supplementary tool when microbe cement is applied in actual engineering projects.

关键词： microbe cement compressive strength calcite numerical model

Effect of Threshold Stress on Anisotropic Creep Properties of Single Crystal Nickel-Base Superalloy SRR99

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Journal of Materials Science & Technology 2012年第5期28卷 439-445页

作者： Cuoming Han Jinjiang yu Xiaofeng Sun Zhuangqi Hu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

The influence of orientation on the creep properties of the nickel-base single crystal superalloy SRR99 was investigated at 760℃ and various levels of applied *** was found that the effect of anisotropy was strikingly prominent at this *** mechanisms of single crystals with three principal orientations at 760℃/790 MPa were explained according to detailed observations of dislocation arrangements by means of transmission electron microscopy （TEM）.Liability to shearing γ＇ precipitates for [011] orientation and co-planar slip for [111] orientation resulted in poor creep strength and short stress rupture *** was also found that the apparent primary creep strain could be measured when the applied stress was increased to 565 *** power law equation was adopted and the concept of a threshold stress σ 0 which determines dislocation looping or shearing to be activated was then *** detailed calculations,the threshold stress was obtained to further analyse the distribution of the applied stress and better rationalize the anisotropic creep behaviour in the stereographic triangle in combination with TEM observations.

关键词： Single crystal superalloy Anisotropic creep Threshold stress Deformation mechanism

Is Yang-Mills theory unitary in fractional spacetime dimensions?

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 59-64页

作者： Qingjun Jin Ke Ren Gang Yang Rui yu Graduate School of China Academy of Engineering Physics Beijing 100193China School of Physics and Astronomy Sun Yat-Sen UniversityZhuhai 519082China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUniversity of Chinese Academy of SciencesHangzhou 310024China International Centre for Theoretical Physics Asia-Pacific Hangzhou 310024China School of Physical Science and Technology Inner Mongolia UniversityHohhot 010021China Beijing Computational Science Research Center Beijing 100193China

We present concrete evidence that Yang-Mills theory exhibits non-unitarity in non-integer spacetime *** violation of unitarity stems from evanescent operators that,while vanishing in four dimensions,are non-zero in general d *** demonstrate that these evanescent operators lead to the emergence of both negative-norm states and complex anomalous dimensions.

关键词： gauge field theories field theories in dimensions other than four renormalization