检索结果-南通市图书馆

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO_4-H_2O and NaF-H_2O binary solutions and NaClO_4-NaF-H_2O ternary solution

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2010年第5期17卷 546-557页

作者： Xue-min Yang Wei-jie Zhao Han-jie Guo Qiang Zhang Jian Zhang State Key Lab of Multiphase Complex System Institute of Process Engineering Chinese Academy of Sciences Beijing 100190 China School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China Beijing Metallurgical Equipment Research ＆ Design corporation Ltd. China Metallurgical Group Corporation Beijing 100029 China

A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory （IMCT）. A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.

关键词： binary systems ternary systems thermodynamic model activity coefficient structural unit

Finite Element Simulation of Rod and Wire Continuous Rolling

在线全文

学校读者我要写书评

暂无评论

Journal of Shanghai Jiaotong university(Science) 2011年第2期16卷 195-198页

作者：张立文岳重祥原思宇阮金华顾森东高慧菊 School of Materials Science and Engineering Dalian University of Technology Dongbei Special Steel Group corporation

This paper discusses the application of several techniques involved in the development of the 3D finite element (FE) models of rod and wire continuous rolling *** FE models are implemented into the FE-program *** and used to investigate the thermal and mechanical behavior of billet during the rolling *** nonlinear equations included in the models are solved by the static and dynamic procedures,*** transfer technique is proposed to keep the continuity of simulation *** the computational time of static procedure is significantly reduced by using a rigid pushing *** all models,the constant time step method and the auto time step method are respectively used to define time step for the solution of *** results of the models with different time step methods are *** comparison between calculated values and measured ones of the temperature at the surface of billet shows the validity of the FE models.

关键词： rod and wire rolling finite element (FE) simulation data transfer auto time step

A Distributed DBMS Based Dynamic Programming Method for Query Optimization

在线全文

学校读者我要写书评

暂无评论

Journal of Donghua University(English Edition) 2012年第1期29卷 55-58页

作者：孙纪舟李阳蒋志勇顾云苏何清法 Beijing Institute of Information and Control The Software Developing Center of China Aerospace Science and Technology corporation

Dynamic programming(DP) is an effective query optimization approach to select an appropriate join order for relational database management system(RDBMS) in multi-table joins. This method was extended and made available in distributed DBMS(D-DBMS). The structure of this optimal solution was firstly characterized according to the distributing status of tables and data, and then the recurrence relations between a problem and its sub-problems were recursively defined. DP in D-DBMS has the same time-complexity with that in centralized DBMS, while it has the capability to solve a much more sophisticated optimal problem of multi-table join in D-DBMS. The effectiveness of this optimal strategy has been proved by experiments.

关键词： distributed database dynamic programming (DP) multitable loin: auery optimization

Simulation solution for micro droplet impingement on a flat dry surface

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2008年第9期17卷 3185-3188页

作者：孙震海韩瑞津 Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Grace Semiconductor Manufacture corporation Graduate School of Chinese Academy of Sciences

This paper presents a computational fluid dynamics approach for micro droplet impacting on a flat dry surface. A two-phase flow approach is employed using FLUENT VOF multiphase model to calculate the flow distributions upon impact. The contact line velocity is tracked to calculate the dynamic contact angle through user defined function program. The study showed that the treatment of contact line velocity is crucial for the accurate prediction of droplet impacting on poor wettability surfaces. On the other hand, it has much less influence on the simulation of droplet impacting on good wettability surfaces. Good fit between simulation results and experimental data is obtained using this model.

关键词： droplet impact wettability contact line velocity dynamic contact angle

High-Order Discontinuous Galerkin solution of Compressible Flows with a Hybrid Lattice Boltzmann Flux

在线全文

学校读者我要写书评

暂无评论

Transactions of Nanjing University of Aeronautics and Astronautics 2018年第3期35卷 413-422页

作者： Sun Yongcheng Cai Junwei Qin Wanglong The 28th Research Institute of China Electronics Technology Group corporation Nanjing 210007P.R.China

A discontinuous Galerkin(DG)-based lattice Boltzmann method is employed to solve the Euler and Navier-Stokes *** of adopting the widely used local Lax-Friedrichs flux and Roe Flux etc.,a hybrid lattice Boltzmann flux solver(LBFS)is employed to evaluate the inviscid flux across the cell *** main advantage of the hybrid LBFS is its flexibility for capturing both strong shocks and thin boundary layers through introducing a function which varies from zero to one to control the artificial *** results indicate that the hybrid lattice Boltzmann flux solver behaves very well combining with the high-order DG method when simulating both inviscid and viscous flows.

关键词： hybrid lattice Boltzmann flux solver discontinuous Galerkin(DG)method Euler equations Navier-Stokes equations

Direction and Trend of Technical Development of Hybrid Vehicles

在线全文

学校读者我要写书评

暂无评论

Direction and Trend of Technical Development of Hybrid Vehic...

20 Years Advances in Preparation of Potassium Salts from Potassic Rocks:A Review

第三十届中国控制会议

作者： Shinichi Abe Toyota Motor corporation

＜正＞Toyota has marketed HV starting from Prius since *** goal is to contribute to spreading personal mobility to all over the world,simultaneously to provide the solution to GHG,energy resource shortage and emission *** practical target is to introduce the power-train whose fuel economy is extremely higher than the conventional gasoline engine system,and its efficiency is also continued to be *** order to realize our target,the reduction of energy usage is necessary by not only improvement of each HV component such as engine,battery,motor/generator and inverter,but innovation of control method to use them in maximum efficiency balance.

关键词： hybrid vehicle PHV control motor generator battery

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Acta Geologica Sinica(English Edition) 2015年第6期89卷 2058-2071页

作者： MA Hongwen YANG Jing SU Shuangqing LIU Meitang ZHENG Hong WANG Yingbin QI Hongbin ZHANG Pan YAO Wengui School of Materials Science and Technology China University of Geosciences Bluesky Technology corporation School of Mathematics and Physics China University of Geosciences

Long-term research on key techniques of clean utilization of potassic rocks from over twenty localities has been performed to settle the shortage of soluble potassium resources in China. The results show that K-feldspar as the principal mineral enriched in potassium could be decomposed in the media of Ca（OH）_2, NaOH, KOH-H_2O solution via hydrothermal treatment, into tobermorite, hydroxylcancrinite, and kalsilite respectively. By further processing, these compounds are feasible for being as slow-release carrier of potassium nitrate, extracting alumina, and preparing farm-oriented fertilizers of potassium sulphate and nitrate. Correspondingly, the filtrate is KOH,（Na, K）_2SiO_3, and K_2SiO_3 solution, from which potassium carbonate, sulphate, nitrate, and phosphate could be easily fabricated. As NaO H and KOH are recycled in the processing chains by causticizing sodium and/or potassium metasilicate solutions, the hydrothermal alkaline techniques as developed in this research have several advantages as lower consumption of disposable mineral resources and energy, maximized utilization of potassic mineral resources, as well as clean productions etc. Based on the approaches presented in this paper, the technical system of efficiently utilizing insoluble potassium resources has been established. The hydrothermal alkaline methods are feasible to be industrialized on a large scale, thus resulting in decreasing imports of potash fertilizers, improving the pattern of potassium fertilizer consumption, and enhancing the supplying guarantee of potassium resource in China.

关键词： K-feldspar potassium salt alkaline digestion green processing sustainable development

Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

在线全文

学校读者我要写书评

暂无评论

International Journal of Minerals,Metallurgy and Materials 2013年第10期20卷 925-930页

作者： Xiao-rong Liu Sheng-cai Jiang Yan-jun Liu Hui Li Hua-jun Wang School of Materials Science and Engineering Shanghai Institute of Technology China Metallurgical Mining corporation Civil and Environmental Engineering School University of Science and Technology Beijing

Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans （A. ferrooxidans）. The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30℃. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%-15.0% stimulates A. ferooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

关键词： titanomagnetite vanadium biodesulfurization Acidithiobacillus ferrooxidans citric acid disodium hydrogenphosphate

Preparation of bimodal grain size 7075 aviation aluminum alloys and their corrosion properties

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 2017年第5期30卷 1777-1788页

作者： Wenming TIAN Songmei LI Jianhua LIU Mei YU Yujie DU AVIC Changhe Aircraft Industry (Group) corporation LTD Jingdezhen 333002 China School of Materials Science and Engineering Beihang University Beijing 100083 China

The bimodal grain size metals show improved strength and ductility compared to traditional metals; however, their corrosion properties are unknown. In order to evaluate the corrosion properties of these metals, the bimodal grain size 7075 aviation aluminum alloys containing different ratios of coarse（100 μm in diameter） and fine（10 μm in diameter） grains were prepared by spark plasma sintering（SPS）. The effects of grain size as well as the mixture degree of coarse and fine grains on general corrosion were estimated by immersion tests, electrochemical measurements and complementary techniques such as scanning electron microscope（SEM） and transmission electron microscope-energy disperse spectroscopy（TEM-EDS）. The results show that, compared to fine grains, the coarse grains have a faster dissolution rate in acidic NaCl solution due to the bigger size,higher alloying elements content and larger area fraction of second phases in them. In coarse grains,the hydrogen ions have a faster reduction rate on cathodic second phases, therefore promoting the corrosion propagation. The mixture of coarse and fine grains also increases the electrochemical heterogeneity of alloys in micro-scale, and thus the increased mixture degree of these grains in metal matrix accelerates the corrosion rate of alloys in acidic NaCl solution.

关键词： 7075 aluminum alloy Corrosion Spark plasma sintering Transmission electron microscope