检索结果-南通市图书馆

PRODUCTIVE GOVERNMENT EXPENDITURE IN A STOCHASTICALLY GROWING OPEN ECONOMY

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2007年第1期20卷 95-107页

作者： haijun wang Shigeng HU Department of Applied Mathematics Shanghai University of Finance and Economics Shanghai 200433 China Department of Mathematics Huazhong University of Science and Technology Wuhan 430074 China.

This paper employs a stochastic endogenous growth model with productive government expenditure in a small open economy to analyze the optimal fiscal policy. First, a stochastic model of a small open economy is constructed. Second, the equilibrium solutions of the representative agent＇s stochastic optimization problem are derived. Third, we obtain the equilibrium solutions of the central planner＇s stochastic optimization problem and the optimal government expenditure policy. Finally, the optimal tax policy is characterized.

关键词： Endogenous growth open economy optimal tax policy productive government expenditure.

Analytical Solution for Three-dimensional Forging Taking into Account Bulging of Sides by Mean Yield Criterion

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2010年第4期23卷 477-483页

作者： DU haijun ZHAO Dewen wang Genji wang Guodong State Key Laboratory of Rolling and Automation Northeastern University Shenyang 110004 China

Currently, for some complex plastic deformations, the analytical solution can not be obtained by using Mises yield criterion, because Mises yield criterion is nine dimensions, the velocity field is complex, and the solving methods are not innovative. Corresponding solutions of these problems are that yield criterion is linearized to reduce the variable numbers, and the velocity field and the solving methods are reasonably simplified, respectively. In this paper, a new linear yield criterion--mean yield（MY） criterion and inner-product of strain rate vector are used to analytically solve 3D forging taking into account bugling of sides. The velocity field is expressed as a vector in three dimensions, and rotation and divergence are applied to confirm that the velocity field is kinematically admissible. Then, the corresponding strain rate tensor of the velocity field is transformed into principal one by making the determinant of coefficients of the tensor cubic equation be zero. By using MY criterion, the plastic power is term by term integrated and summed according to inner-product of strain rate vector. An upper bound analytical solution is obtained for the forging, and verified by a pure lead press test. The test result turns out that the total pressure calculated by MY criterion is higher by 2.5%-15% than measuring value. In addition, a measuring formula of bulging parameter （a） is proposed, but the values of a measured by the formula are lower than those optimized by the golden section search. The total pressure calculated by MY criterion is compared with the ones by twin shear, Trasca yield, and Mises yield criterion. The comparing result shows that the total pressure calculated by MY criterion is slightly higher than the mean value of that by twin shear and Trasca yield criterion, and lower than that by Mises yield criterion, but more close to that by Mises yield criterion compared with that by other two. The proposed analytical solving methods can be effectively

关键词： mean yield criterion three-dimensional forging bulging strain rate vector inner-product

Preparation of copper net-supported metal-organic framework-5 membranes for solid-state lasers

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2011年第6期54卷 947-950页

作者： wang haijun SHA ZiJian Department of Pharmacy Qiqihar Medical University Qiqihar 161006 China

Continuous copper net-supported metal-organic framework (MOF-5) membranes of high quality are synthesized for the first time by vapor diffusion of an organic amine. The velocity of diffusion of the organic amine and reaction temperature directly affect the quality of the membranes formed. Furthermore, a laser dye is successfully encapsulated within such membranes in CHCl3. The dye-loaded MOF-5 membranes have potential applications in optics, especially in laser systems.

关键词： membranes metal-organic frameworks dye fluorescence

Macrozoobenthic assemblages in relation to environments of the Yangtze-isolated lakes

在线全文

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2012年第2期6卷 246-254页

作者： Baozhu PAN haijun wang Hongzhu wang Zhaoyin wang State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China Changjiang River Scieniific Research Institute Wuha~430010China State Key Laboratory of Hydroscience and Engineering Tsinghua UniversityBeijing 100084China

Eutrophication can shift lakes from a clear, macrophyte-dominated state state, and different habitat to a turbid, algae-dominated condition supports different fauna. Macrozoobenthos are good indicators of water environment, and studies on macrozoobenthic assemblage characteristics can help us to know which state a lake is in, thus provide the basis for its eutrophication control. In this study, a systematic investigation on macrozoobenthos was conducted in 17 Yangtze-isolated lakes to explore the macroecological laws of macrozoobenthic assemblages. Detrended correspondence analysis （DCA） revealed that variance of benthic assemblage structure occurred in two types of lakes. In macrophytic lakes, altogether 51 taxa of macrozoobenthos were identified. The average density and biomass of total macrozoobenthos were 2231 individuals, m2 and 1.69 g dry weight.m-2, respec- tively. Macrozoobenthic assemblage was characterized by dominance of scrapers （i.e. gastropods）. In algal lakes, altogether 20 taxa of macrozoobenthos were identified. The average density and biomass of total macrozoobenthos were 2814 individuals.m^2 and 1.38g dry weight.m-2, respectively. Macrozoobenthic assemblage was character- ized by dominance of collector-gatherers （i.e. oligo- chaetes）. Wet biomass of submersed macrophytes （BMac） and phytoplankton chlorophyll a concentration （Chla） were demonstrated as the key factor structuring macro- zoobenthic assemblages in macrophytic and algal lakes, respectively.

关键词： macrozoobenthos assemblage characteristics,environment analyses macrophytic lake algal lake

Experimental Study on Condensation Heat Transfer Characteristics inside an Inclined Wave-Finned Flat Tube of Direct Air-Cooling System

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Thermal Science 2021年第2期30卷 432-440页

作者： wang Haitao TAO Tao MEI Xuesong wang haijun GU Hongfang State Key Laboratory for Manufacturing Systems Engineering Xi'an Jiaotong UniversityXi'an 710049China Shaanxi Key Laboratory of Intelligent Robots School of Mechanical EngineeringXi'an Jiaotong UniversityXi'an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In this paper,the condensation heat transfer characteristics of parallel flow and counter flow inside an inclined wave-finned flat tube is investigated *** condensation heat transfer coefficients are analyzed based on the experimental *** of experiments show that condensation heat transfer coefficient decreases as the temperature difference Δt=ts-tw increases and mass flow rate *** parallel flow has a similar development with the counter flow,and the condensation heat transfer coefficient of counter flow is less than that of parallel flow under the same air cooling *** addition,condensation heat transfer coefficient correlations are also obtained under experimental *** calculations agree well with the measured data and the agreement is seen to be within ±4% for the parallel flow and ±5% for the counter flow.

关键词： condensation heat transfer wave-finned fiat tube modified model parallel flow counter flow

Preparation and crystalline phase of a TiO_2 porous film by anodic oxidation

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2005年第4期24卷 330-335页

作者： wang Wei TAO Jie ZHANG Weiwei TAO haijun wang Ling College of Material Science and Technology Nanjing University of Aeronautics ＆ Astronautics Nanjing 210016 China

Anatase titanium dioxide is an active photocatalyst, but it is difficult to immobilize on the substrate. A crystalline TiO2 porous film was prepared directly on the surface of pure titanium by anodic oxidation in this work. Constant voltage and constant current anodic oxidation were adopted with sulphuric acid used as the electrolyte, pure titanium as the anode and copper as the cathode. The morphology and structure of the porous film on the substrate were analyzed with the aid of Field Emission Scanning Electron Microscopy （FESEM） and X-ray Diffraction （XRD）. The effects of the parameters of anodic oxidation （such as voltage, the concentration of sulphuric acid, anodization time and current density） on the aperture and the crystalline phase of the TiO2 porous film were systematically investigated. The results indicate that the increase of current density facilitates the augment of the aperture and the generation of anatase and mille. In addition, the forming mechanism of anatase and mille TiO2 porous films was discussed.

关键词： metal materials titanium oxide porous film anodic oxidation anatase rutile

Statistical thermodynamic properties of a new self-condensing vinyl polymerization system

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2015年第9期58卷 1478-1488页

作者： Zuofei Zhao Yuanfeng Li Ning Yao haijun wang Faculty of Physics and Electronic Information Langfang Teachers University College of Chemistry and Environmental Science Hebei University International Centre for Materials Physics Chinese Academy of Sciences

A new self-condensing vinyl polymerization system consisting of *ABf-type inimers is studied by the principle of statistical mechanics. To obtain the relevant average properties of the system, a differential equation satisfied by the polymeric moment of interest is given, and as a result the zeroth, first, second, and third polymeric moments together with the size distribution function of hyperbranched polymers(HBPs) are explicitly presented. As an application of the method of statistical mechanics, several thermodynamic quantities such as the equilibrium free energy, law of mass action, isothermal compressibility, internal energy, and the specific heat associated with the polymerization are all derived. Furthermore, the scaling behavior of asymptotic size distribution function is discussed, by which a reasonable interpretation of the polydispersity index near the end of polymerization can be made. Also, the expressions of some structural parameters such as the numbers of inimers, terminal units, chain units, branched units, and the degree of branching(DB) are calculated. It is found that a high functionality is helpful to improve the DB of the resultant HBPs. These results show that the functionality f has a significant effect on the thermodynamic quantities and structural properties of HBPs.

关键词： partition function law of mass action internal energy and specific heat polydispersity index structural parameter

The radius of gyration for a ternary self-condensing vinyl polymerization system

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2015年第12期58卷 1875-1883页

作者： Xiaozhong Hong Zuofei Zhao haijun wang Xinwu Ba College of Physical Science and Technology Hebei University Faculty of Physics and Electronic Information Langfang Teachers University College of Chemistry and Environmental Science Hebei University International Centre for Materials Physics Chinese Academy of Sciences

A ternary self-condensing vinyl polymerization(SCVP) system consisting of monomers, inimers and core initiators is studied by the principle of statistical mechanics. Starting from partition functions for polymerization that constructed from two different viewpoints, explicit expressions of the size distribution function(SDF), equilibrium free energy, and the law of mass action are obtained. For two types of hyperbranched polymers(HBPs) formed in the system, the first, the second, and the third mean-square radii of gyration(MSRG) are presented under various conditions. Furthermore, the solvent effect and excluded volume effect are taken into account in the calculation of the MSRG. With these results, the effects of monomers, inimers and core initiators on the spatial dimension of HBPs are discussed. It is shown that the competition between polymers with and without a core in the growing process results in a significant influence on the average properties of the system.

关键词： ternary SCVP system equilibrium free energy law of mass action MSRG solvent effect excluded volume effect

Statistical and thermodynamic properties of binary self-condensing vinyl polymerization

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China Chemistry 2011年第3期54卷 438-445页

作者： GU Fang wang haijun ZHAO ZuoFei College of Chemistry and Environment Science Hebei University Baoding 071002 China International Centre for Materials Physics Chinese Academy of Sciences Shenyang 110016 China Key Laboratory of Medicinal Chemistry and Molecular Diagnosis Ministry of Education Hebei University Baoding 071002 China

The thermodynamic properties of a binary self-condensing vinyl polymerization system consisting of monomers and inimers are investigated by the principle of statistical *** detail,in terms of two types of canonical partition functions constructed from different viewpoints,the equilibrium free energy,the law of mass action and the size distribution of hyperbranched polymers are *** an application,the specific heat,equation of state and isothermal compressibility concerning the polymerization are given as *** study the dimension of hyperbranched polymers in the system,a recursion formula satisfied by the(k+1)-th and k-th mean square radius of gyration is derived,and then the first,second and third radius of gyration under different solvent conditions are *** influences of the fraction of inimers,the conversion of vinyl groups and the solvent effect on the average dimension of hyperbranched polymers are discussed.

关键词： self-condensing vinyl polymerization law of mass action mean square radius of gyration solvent effect