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Solubility and Thermodynamic Properties of Sulfamethazine-Saccharin Cocrystal in Pure and Binary (Acetonitrile + 2-Propanol) Solvents

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Transactions of Tianjin University 2021年第6期27卷 460-472页

作者： Hongyuan wei Ningcan gao Leping Dang School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China

In this work,a new crystallization method was used to prepare two polymorphs of sulfamethazine-saccharin(SMT-SAC)cocrystal in *** purity and crystal form of both polymorphs were confirmed by optical microscopy,scanning electron microscopy,powder X-ray diff raction,diff erential scanning calorimetry,and thermogravimetric ***,the solubility of the stable form(form Ⅱ)was determined by gravimetric analysis in nine pure solvents and one binary(acetoni-trile+2-propanol)solvent at temperatures ranging from 278.15 to 348.15 K at atmospheric *** data were correlated using the modified Apelblat model,theλh equation,the nonrandom two-liquid(NRTL)model,the Jouyban-Acree model,and the CNIBS/Redlich-Kister ***,the apparent thermodynamic properties,such asΔ_(dis)G,Δ_(dis) H,andΔ_(dis) S,were calculated on the basis of the activity coefficient obtained by the NRTL *** the models correlate well,and all the experimental and calculated results indicate that the dissolution behavior of SMT-SAC cocrystal form II is a spontaneous,endothermic,and entropy-driven process.

关键词： Sulfamethazine-saccharin cocrystal Solid-liquid equilibrium Thermodynamic model Dissolution thermodynamic property

Anand Parameters Determination for SnAgCu Solder Bearing Micro-amounts Rare Earth Ce

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Chinese Journal of Mechanical Engineering 2010年第2期23卷 257-262页

作者： ZHANG Liang XUE Songbai gao Lili CHEN Yan YU shenglin sheng Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China Harbin Welding Institute Harbin 150080 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

SnAgCu solder system with the addition of rare earth Ce, which has better thermo-mechanical properties compared to those of SnPb solder, is regarded as one of the promising candidates for electronic assembly. Moreover, the SnAgCuCe solder alloys can provide good quality joints with Cu substrates. However, there is few report of the constitutive model for SnAgCu solder bearing micro-amounts rare earth Ce. In this paper, the unified viscoplastic constitutive model, Anand equations, is used to represent the inelastic deformation behavior for SnAgCu and SnAgCuCe solders. In order to obtain the acquired data for the fitting of the material parameters of this unified model, a series of experiments of constant strain rate test were conducted under isothermal conditions at different temperatures. The Anand parameters of the constitutive equations for SnAgCu and SnAgCuCe solder were determined from separated constitutive relations and experimental results. Nonlinear least-square fitting was selected to determine the model constants. And the simulated results were then compared with experimental measurements of the stress-inelastic strain curves： excellent agreement was found. The model accurately predicted the overall trend of steady-state stress-strain behavior of SnAgCu and SnAgCuCe solders for the temperature ranges from 25℃ to 150 ℃, and the strain rate ranges from 0.01 s^-1 to 0.001 s ^-1. It is concluded that the Anand model can be applied for representing the inelastic deformation behavior of solders at high homologous temperature and can be recommended for finite element simulation of the stress-strain response of lead free soldered joints. Based on the Anand model, the investigations of thermo-mechanical of SnAgCu and SnAgCuCe soldered joints in fine pitch quad flat package by finite element code were done under thermal cyclic loading, it is found that the reliability of SnAgCu soldered joints can be improved remarkably with addition of rare earth Ce. The results ma

关键词： Anand equations constitutive relations SnAgCuCe solders rare earth reliability

Unification of Filled Function and Tunnelling Function in Global Optimization

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Acta Mathematicae Applicatae Sinica 2007年第1期23卷 59-66页

作者： wei Wang Yong-jian Yang Lian-sheng Zhang Department of Mathematics East China University of Science and Technology Shanghai 200237 China Department of Mathematics Shanghai University Shanghai 200444 China

In this paper, two auxiliary functions for global optimization are proposed. These two auxiliary functions possess all characters of tunnelling functions and filled functions under certain general assumptions. Thus, they can be considered as the unification of filled function and tunnelling function. Moreover, the process of tunneling or filling for global optimization can be unified as the minimization of such auxiliary functions. Result of numerical experiments shows that such two auxiliary functions are effective.

关键词： Nonlinear programming global optimization filled function tunnelling function unification

Geographical Differences and Influencing Factors of Rural Energy Consumption in Southwest Mountain Areas in China:A Case Study of Zhaotong City

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Journal of Mountain Science 2012年第6期9卷 842-852页

作者： SUN wei HAN Xiaoxu sheng Kerong FAN Jie Institute of Geographic Sciences and Natural Resources Research Chinese Academy of SciencesBeijing 100101China Key Laboratory of Regional Sustainable Development Modeling Chinese Academy of SciencesBeijing 100101China China Urban Construction Design and Research Institute Beijing 100120China Shandong University of Technology Shandong 255049China

China is a mountainous country,and Southwest mountain areas cover the most mountain areas in China and have the most serious *** Zhaotong city as the study area,based on 902 rural household questionnaires of 11 villages in 2 counties and Tobit model,this paper analyzes the geographical differences and influencing factors of energy consumption for non-production purposes of rural households living in different terrain *** research finds that:(1) Coal takes up the main part of energy consumption in valley areas and coal consumption is mainly affected by per capita cultivated land area,household income,proportion of rural household energy expenditure in total expenditure,coal price,and family population *** takes up the main part of energy consumption in high mountain areas and firewood consumption is mainly affected by per capita firewood forest area,distance to purchase coal,household income,electricity price,and coal price.(2) Only when the distance is greater than 20 kilometers,that is the average distance of rural households living in middle mountain areas(1,600m^1,800m) to purchase coal,the transportation condition has a significant impact on coal consumption.(3) In high mountain areas,prices of coal and electricity are the main factors influencing energy consumption choice of rural *** high prices of coal and electricity would to some extent lead rural households to choose firewood as the main energy consumption *** to coal,rural households prefer to choose electricity.

关键词：能源消费农村家庭西南山区影响因素地域差异昭通市中国人均耕地面积

Effect of Thermal Cycling on Properties and Microstructure of SnAgCuCe Soldered Joints in QFP Devices

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Chinese Journal of Mechanical Engineering 2011年第4期24卷 561-566页

作者： ZHANG Liang XUE Songbai gao Lili ZENG Guang YU shenglin sheng Zhong College of Materials Science and Technology Nanjing University of Aeronautics and Astronautics Nanjing 210016 China School of Mechanical ＆ Electrical Engineering Xuzhou Normal University Xuzhou 221116 China The 14th Research Institute China Electronics Technology Group Corporation Nanjing 210013 China

Increasing global concern about the environment is bringing regulatory （European directives） and consumer （＂green products＂） pressure on the electronics industry in Europe and Japan to reduce or completely eliminate the use of lead （Pb） in products. Among all lead-free solder alloys, SnAgCu solder system, which has better thermo-mechanical properties compared with those of SnPb solder, is proven to be one of the promising candidates for electronic assembly. Previous work also revealed that adding a small amount of rare earth Ce into SnAgCu solder can visibly improve the properties and inhibit the excessive growth of the intermetallic compound layer. Thermal fatigue properties of SnAgCuCe soldered joints in QFP devices under thermal conditions have been investigated by finite element method and experiments. Based on creep model of low stress and high stress, corresponding creep subroutine was established for simulating the stress and strain response of SnAgCuCe soldered joint from -55 ℃ to 125 ℃, and fatigue life was calculated using creep fatigue life prediction equation. Moreover, thermal cycling experiments were conducted, the experimental results were found to be close to the simulated results. In addition, the tensile force of SnAgCuCe soldered joints decreased with increasing number of thermal cycles, and the fracture mechanism transformed from toughness fracture to brittle intergranular fracture. Moreover the tensile force changes and fracture microstructure evolution could benefit the quantitative evaluations of the mechanical performances of lead-free soldered joints under thermal cycling loadings.

关键词： finite element method creep equation thermal cycling fatigue life

Automated enforcement for relaxed information release with reference points

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Science China(Information Sciences) 2014年第11期57卷 131-149页

作者： SUN Cong XI Ning gao sheng CHEN Zhong MA JianFeng School of Computer Science and Technology Xidian University School of Electronics Engineering and Computer Science Peking University

Language-based information flow security is a promising approach for enforcement of strong security and protection of the data confidentiality for the end-to-end communications. Here, noninterference is the standard and most restricted security property that completely forbids confidential data from being released to public context. Although this baseline property has been extensively enforced in various cases, there are still many programs, which are considered secure enough, violating this property in some way. In order to control the information release in these programs, the predetermined ways should be specified by means of which confidential data can be released. These intentional releases, also called declassifications, are regulated by several more relaxed security properties than noninterference. The security properties for controlled declassification have been developed on different dimensions with declassification goals. However, the mechanisms used to enforce these properties are still unaccommodating, unspecific, and insufficiently studied. In this work, a new security property, the Relaxed Release with Reference Points(R3P), is presented to limit the information that can be declassified in a program. Moreover, a new mechanism using reachability analysis has been proposed for the pushdown system to enforce R3 P on programs. In order to show R3 P is competent for use, it has been proved that it complies with the well-known prudent principles of declassification, and in addition finds some restrictions on our security policy. The widespread usage, precision, efficiency, and the influencing factors of our enforcement have been evaluated.

关键词： information flow security policy noninterference declassification pushdown system program analysis

An immune-tabu hybrid algorithm for thermal unit commitment of electric power systems

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2009年第6期10卷 877-889页

作者： wei LI Hao-yu PENG wei-hang ZHU De-ren sheng Jian-hong CHEN School of Mechanical and Energy Engineering Zhejiang University Hangzhou 310027 China Department of Industrial Engineering Lamar University Beaumont 77710-0032 USA

This paper presents a new method based on an immune-tabu hybrid algorithm to solve the thermal unit commitment (TUC) problem in power plant optimization. The mathematical model of the TUC problem is established by analyzing the gen-erating units in modern power plants. A novel immune-tabu hybrid algorithm is proposed to solve this complex problem. In the algorithm, the objective function of the TUC problem is considered as an antigen and the solutions are considered as antibodies, which are determined by the affinity computation. The code length of an antibody is shortened by encoding the continuous oper-ating time, and the optimum searching speed is improved. Each feasible individual in the immune algorithm (IA) is used as the initial solution of the tabu search (TS) algorithm after certain generations of IA iteration. As examples, the proposed method has been applied to several thermal unit systems for a period of 24 h. The computation results demonstrate the good global optimum searching performance of the proposed immune-tabu hybrid algorithm. The presented algorithm can also be used to solve other optimization problems in fields such as the chemical industry and the power industry.

关键词：混合算法免疫算法电力系统禁忌单位职工大会 Tabu搜索计算结果

International carbon markets under the Paris Agreement:Basic form and development prospects

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Advances in Climate Change Research 2019年第1期10卷 21-29页

作者： gao Shuai LI Meng-Yu DUAN Mao-sheng WANG Can State Key Joint Laboratory of Environment Simulation and Pollution Control(SKLESPC) and School of EnvironmentTsinghua UniversirBeiying100084China Institute of Energy Environment and EconomyTsinghua UniversityBeijing100084China

Article 6 of the Paris Agreement introduces two international carbon markets that receive extensive attention and are expected to play an important role in the post-2020 climate *** key elements of the two international carbon markets,including the scope,the types of tradable units and the governance,are identified,as the basis to clarify their basic *** on the key issues and their different designs identified in negotiations,this study analyzes the contributions and challenges for China to participate in international carbon *** the inherent needs of climate change mitigation,climate finance,the development of a green"Belt and Road"and the China South-South cooperation in climate change,along with the existing domestic capacities on market mechanisms,this study puts forward the short-,medium-and long-term development prospects of the two international carbon markets.

关键词： Paris Agreement International carbon markets Cooperative approaches Sustainable development mechanism Climate change

Synthesis,Crystal Structure and Nonisothermal Kinetics of Complex Co(tda)(5-mphen)(H_2O)

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Chemical Research in Chinese Universities 2009年第3期25卷 383-387页

作者： HOU Xiang-yang CHEN San-ping gao sheng-li Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education College of Chemistry ＆ Materials Science Northwest University Xi＇an 710069 P. R. China Department of Chemistry Yan＇an University Yan＇an 716000 P. R. China

The title complex, formulated as Co（tda）（5-mphen）（H2O）（H2tda=thiodiglycolic acid, 5-mphen= 5-methyl-1,10-phenanthroline）, was synthesized and characterized by elemental analysis, IR spectroscopy, X-ray single crystal diffraction, and TG-DTG techniques. The complex crystallized in monoclinic space group C2/c, with parameters of a=1.8142（2） nm, b=0.78251（9） nm, c=2.4624（3） nm,β=93.809（2）°, V=3.4880（7） nm^3, Z=8, Dc=1.579 g/cm^3, the final R indices[1〉2σ（1）] are R1=0.0469, wR2=0.1021, R indices for all data are R1=0.0835, wR2=0.1169. The central Co^2＋ cation is coordinated in a distorted octahedral geometry with the ligand tda, 5-mphen, and water molecule. The coordination complex possesses a three-dimensional framework by means of hydrogen bonds and π-π stacking interactions. According to TG-DTG curves, the possible thermal decomposition mechanisms, the possible kinetic parameters, and equation of dehydration stage of the complex are obtained, that is, Ea=110.98 kJ/mol, lg（A/s^-1）=8.554, da/dT= 10^8.5546/β.3（1-α）[-1n（1-α）]^2/***（-13349/T）, respectively.

关键词： Co(tda)(5-mphen)(H2O) Crystal structure Kinetics of thermal decomposition