检索结果-南通市图书馆

Preparation and Kinetics of the Thermal Decomposition of Nanosized CuC_2O_4-ZnC_2O_452H_2O

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2006年第3期11卷 667-671页

作者： CHEN Donghua HUANG Lianrong TANG Wanjun hubei Key Laboratory for Catalysis and Material Science/College of Chemical and Materal Science South-Central University for Nationalities Wuhan 430074 Hubei China

The physical mixture of nanosized CuC2O4-ZnC2O4·2H2O, as precursors of CuO-ZnO, have been prepared by the one-step solid state reaction method at room temperature. The thermal decomposition processes taking place in the solid state oxalate mixture of nanometer CuC2O4-ZnC2O4·2H2O have been studied in static air using TG, DSC, XRD and TEM techniques. TEM showed that the grain size of the decomposition product is 5-15 nm. The values of the activation energy Eα were determined using the isoconversional procedure of KAS method and the Ozawa method. The most possible mechanism function f（α） of the thermal decompositions of nanosized CuC2O4-ZnC2O4·2H2O are defined using the comparative method, function models of tbe decomposition of CuC2O4 and ZnC2O4, follow tbe same mechanism function ＂Avrami-Erofeev equalion＂. The pre-exponential factor A is obtained on the basis of Eα and f（α）, thus the thermal analysis kinetic triplet of the decompositions of nanosized CuC2O4-ZnC2O4·2H2O are determined.

关键词： nanoparticle copper oxalate zinc oxalate kinetics characterization

The Markov-Dependent Risk Model with a Threshold Dividend Strategy

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2011年第3期16卷 193-198页

作者： LIU Juan XU Jiancheng HU Hongchang School of Mathematics and Statistics Hubei Normal University Huangshi 435002 Hubei China

This paper studies a Markov-dependent risk model in which the claim occurrence and the claim amount are regulated by an external discrete time Markov process. Integro-differential equations in matrix form for the Gerber-Shiu discounted penalty function are presented. Then the analytical solutions to the equations are derived. Finally, in the two-state model, some numerical results are obtained when claim amount is exponentially distributed.

关键词： Markov-dependent threshold dividend strategy Gerber-Shiu function analytical solution

Gene? Meme? Translation?

在线全文

学校读者我要写书评

暂无评论

Comparative Literature:East & West 2009年第1期 127-135页

作者： ZHANG Ting hubei University for Nationalities

自"文化转向"以来,翻译研究逐渐摆脱孤立的文本内研究,开始关注文本外因素。同时,其他学科的发展也为翻译研究提供了更多的思考角度,使翻译的跨学科特点更为明显。但却使得翻译作为独立学科的边界越来越模糊。本文试图从"模因"这比附"基... 详细信息

自"文化转向"以来,翻译研究逐渐摆脱孤立的文本内研究,开始关注文本外因素。同时,其他学科的发展也为翻译研究提供了更多的思考角度,使翻译的跨学科特点更为明显。但却使得翻译作为独立学科的边界越来越模糊。本文试图从"模因"这比附"基因"概念而创设的理论的实质出发,重点考察"模因"论与"共核"等概念所指间具有的内在一致性,以期探讨"模因论"对翻译理论研究及翻译教学的启示。

关键词：翻译研究模因文化转向文本概念翻译理论研究学科特点独立学科翻译教学基因

Optimal Portfolio Selection Strategies under Some Constraints

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2009年第4期14卷 281-286页

作者： LUO Kui,WANG Guangming,HU Yijun School of Mathematics and Statistics,Wuhan University,Wuhan 43.072,hubei,China School of Mathematics and Statistics Wuhan University Wuhan 430072 Hubei China

A portfolio selection problem for any utility function is introduced, where all the market coefficients are random and the wealth process under any admissible trading strategy is not allowed to be below a benchmark wealth process. The problem is completely solved using a decomposition approach. First, the portfolio selection problem is formulated, and its feasibility is characterized. Then, the problem is decomposed to two steps to solve. After a system of equations for a Lagrange multiplier is solved, the portfolio selection problem is derived as the replicating portfolios of contingent claims. Finally, some simulations are demonstrated.

关键词： portfolio selection Lagrange multiplier stochastic differential equation Monte-Carlo simulation

An Improved Intra-Prediction Algorithm for H.264

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2010年第4期15卷 340-344页

作者： WU Bentao, WU Minyuan School of Electronic Information, Wuhan University, Wuhan 43.072, hubei, China School of Electronic Information Wuhan University Wuhan Hubei China

H.264 improves the coding efficiency by adopting rate distortion optimization (RDO); however,it yields high computa-tional complexity. In order to reduce the intra-frame coding time,a fast and effective intra-prediction mode selection algorithm is proposed. The minimum sum of absolute differences between sub-block and its marginal weighted-pixels are used for selecting the candidates of prediction modes to speed up the intra-prediction process with an early termination criterion. Experimental results show that the proposed method can reduce the encoding time by more than 63% comparing with JM (Joint Model) software and is better than the previous algorithms,with negligible loss of coding performance.

关键词： H.264 intra-prediction rate distortion optimization (RDO) prediction mode selection

A Semantic Retrieval Method Based on the Fuzzy Reasoning

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2002年第2期7卷 169-173页

作者： Cao Jia-heng,Liu Juan,Peng Min,Shu Feng-di School of Computer,Wuhan University,Wuhan 43.072,hubei, China Wuhan University School of Computer Wuhan Hubei China (GRID:grid.49470.3e) (ISNI:***)

This paper gives a semantic fuzzy retrieval method of multimedia object, discusses the principle of fuzzy semantic retrieval technique, presents a fuzzy reasoning mechanism based on the knowledge base, and designs the... 详细信息

关键词： Key words semantic retrieval fuzzy reasoning knowledge base multimedia object

3-D Lightning Location Solution and Precision Analysis of Cloud Flash

在线全文

学校读者我要写书评

暂无评论

Wuhan University Journal of Natural Sciences 2009年第3期14卷 241-244页

作者： ZHANG Ping1,2, ZHAO Wenguang2,3?, HU Zhixiang2,3, WEN Yinping2,3 1. School of Architecture and Urban Planning, Huazhong University of Science and Technology, Wuhan 430074, hubei, China 2. School of Civil Engineering and Mechanics, Huazhong University of Science and Technology, Wuhan 430074, hubei, China 3. hubei Key Laboratory of Control Structure, Huazhong University of Science and Technology, Wuhan 430074, hubei, China School of Architecture and Urban Planning Huazhong University of Science and Technology Wuhan 430074 Hubei China School of Civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 Hubei China hubei Key Laboratory of Control Structure Huazhong University of Science and Technology Wuhan 430074 Hubei China

Using the spatial coordinates of detection stations and the time of arrival of lightning wave, the observation equations can be expressed. For the large lightning detection network, the least square method is used to process the adjustment of observation data to find the most probable value of lightning position, and the result is assessed by the mean error and dilution of precision. Lightning location precision is affected by figure factor. The conclusion can be used in the design of location network, data processing, and data analysis.

关键词： 3-D lightning location cloud flash detection solution model dilution of precision figure factor

Forecasting Loss of Ecosystem Service Value Using a BP Network: A Case Study of the Impact of the South-to-north Water Transfer Project on the Ecological Environmental in Xiangfan, hubei Province, China

在线全文

学校读者我要写书评

暂无评论

Biomedical and Environmental Sciences 2003年第4期16卷 379-391页

作者： YUN-FENG CHEN, JING-XUAN ZHOU, JIE XIAO, AND YAN-PING LIEnvironmental Science and Engineering College, Huazhong University of Science and Technology, Wuhan 430074, hubei, China Environmental Science and Engineering College Huazhong University of Science and Technology Wuhan 430074 Hubei Chin

Objective To recognize and assess the impact of the South-to-north Water Transfer Project (SNWTP) on the ecological environment of Xiangfan, hubei Province, situated in the water-out area, and develop sound scientific countermeasures. Methods A three-layer BP network was built to simulate topology and process of the eco-economy system of Xiangfan. Historical data of ecological environmental factors and socio-economic factors as inputs, and corresponding historical data of ecosystem service value (ESV) and GDP as target outputs, were presented to train and test the network. When predicted input data after 2001 were presented to trained network as generalization sets, ESVs and GDPs of 2002, 2003, 2004... till 2050 were simulated as output in succession. Results Up to 2050, the area would have suffered an accumulative total ESV loss of RMB 104.9 billion, which accounted for 37.36% of the present ESV. The coinstantaneous GDP would change asynchronously with ESV, it would go through an up-to-down process and finally lose RMB89.3 billion, which accounted for 18.71% of 2001. Conclusions The simulation indicates that ESV loss means damage to the capability of socio-economic sustainable development, and suggests that artificial neural networks (ANNs) provide a feasible and effective method and have an important potential in ESV modeling.

关键词： Artificial neural network BP Ecosystem service value South-to-north Water Transfer Project

INTERACTION OF COMPONENTS IN PETROLEUM CARBOXYLATE/ALKALINE/HYDROLYZED POLYACRYLAMIDE FLOODING SYSTEM

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 1993年第3期4卷 279-280页

作者： HONG DU HUANG LIN ZHAO Jianghan Petroleum Institute,Jiangling,hubei,434102

The IFTs(Interfacial tension)of petroleum carboxylate/alkaline/HPAM(Hydrolyzed polyacrylamide)flooding system with Daing crude oil and the effects of petroleum carboxylate and alkaline on viscoaity of HPAM solution were *** exists remarkable synergism between HPAM and petroleum carboxylate,and the introduction of HPAM into petroleum carboxylate/alka- line system leads the lowering of IFTs against Daqing crude oil,The introduction of petroleum carboxylate into solution of HPAM also leads the decreasing of viscosity,but the extent of viscosity decreasing is much lower than that caused by inorganic salts such as NaCl and CaCl_2.

关键词： HPAM this INTERACTION OF COMPONENTS IN PETROLEUM CARBOXYLATE/ALKALINE/HYDROLYZED POLYACRYLAMIDE FLOODING SYSTEM IFT than EOR