检索结果-南通市图书馆

China's meat and grain imports during 2000–2012 and beyond: A comparative perspective

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2015年第6期14卷 1101-1114页

作者： YU wu-sheng CAO Li-juan Department of Food and Resource Economics University of Copenhagen College of Economics and Management Nanjing Agricultural University China Center for Food Security Research Nanjing Agricultural Universtiy

This paper provides a review on China＇s meat trade for the 2000–2012 period and discusses its future development, with reference to China＇s grain trade. With marginal decreases in meat exports and slight increases in their imports, China＇s net imports of major meat products（including pork, beef, mutton and poultry but excluding meat offal） were just below 1 million tons in 2012, dwarfed by China＇s net imports of grains which reached 66.7 million tons in the same year. This slow growth in meat trade seems to contradict earlier expectations on increasing meat demand and imports, based upon projected shifts in consumption patterns driven by rapid per capita income growth. Several plausible explanations of this paradoxical trade pattern are offered, including mass imports of feed grains, persistent（but shrinking） gaps between Chinese and international meat prices, tariff barriers, and non-tariff measures. In the near future China may not be able to maintain such a lower profile on the world meat markets, as per capita income is projected to continue to rise and domestic production cost advantages erode due to rising labor costs. A model-based projection exercise indicates that under plausible assumptions China＇s meat imports may rise sharply by 2030.

关键词： imports and beyond tariff prices capita income excluding earlier projection quota

Fixed Points for Mean Non-expansive Mappings

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2007年第3期23卷 489-494页

作者： Chun-xue wu Li-juan Zhang Department of Mathematics Yantai University Yantai 264005 China

For a Banach Space X Garcia-Falset introduced the coefficient R（X） and showed that if R（X）〈 2 then X has a fixed point. In this paper, we define a mean non-expansive mapping T on X in the sense that ｜｜Tx - TY｜｜ ≤ a｜｜x - y｜｜＋ b｜｜x - Ty｜｜ for any x,y E X, where a,b ≥ 0, a ＋ b ≤ 1. We show that if R（X）〈 1/1＋b then T has a fixed point in X.

关键词： Fixed point property mean non-expansive mapping normal structure

A Note on List Edge and List Total Coloring of Planar Graphs without Adjacent Short Cycles

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2014年第1期30卷 91-96页

作者： Hui juan WANG Jian Liang wu School of Mathematics Shandong University

LetGbe a planar graph with maximum degreeΔ.In this paper,we prove that if any4-cycle is not adjacent to ani-cycle for anyi∈{3,4}in G,then the list edge chromatic numberχl（G）=Δand the list total chromatic number... 详细信息

关键词： List edge coloring list total coloring planar graph cycle

Model of Forming-Accretion on Blast Furnace Copper Stave and Industrial Application

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2012年第7期19卷 1-5页

作者： wu Tong CHENG su-sen School of Metallurgical and Ecological Engineering University of Science and Technology Beijing Beijing 100083 China

Copper staves have been equipped on nearly all of BF （blast furnaces） with volume over than 1000 m3 in China since their introduction from abroad about more than 10 years ago. Because of short application and lack of experience, phenomena of thickened or naked of copper stave happen occasionally which influence production severely. So it is important to study the model of forming-accretion on BF copper stave and realize real-time monitoring of forming-accretion on different copper staves. Therefore, mathematic model of calculating accretion thickness by heat flow of BF is proposed, and the calculated results indicate that accretion thickness could be kept at a reasonable range of around 50 mm by controlling heat flux around 22.0 kW/mz. The monitoring program based on the model was applied to a certain BF in China successfully, and it is found that slip of BF near the inner wall is one of most important reasons that cause fluctuation of accretion thickness. During the period of scheduled maintenance of the certain BF, the thickness of accretion measured through the static pressure holes is in good accordance with the value calculated by the monitoring program, so the results calculated by the monitoring program can be used to guide industrial production

关键词： blast furnace copper stave forming-accretion monitor industrial application

Convergence analysis of a nonlinear Lagrange algorithm for general nonlinear constrained optimization problems

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics(A Journal of Chinese Universities) 2014年第3期29卷 352-366页

作者： HE su-xiang wu Li-xun School of Science Wuhan University of Technology

The convergence analysis of a nonlinear Lagrange algorithm for solving nonlinear constrained optimization problems with both inequality and equality constraints is explored in detail. The estimates for the derivatives of the multiplier mapping and the solution mapping of the proposed algorithm are discussed via the technique of the singular value decomposition of matrix. Based on the estimates, the local convergence results and the rate of convergence of the algorithm are presented when the penalty parameter is less than a threshold under a set of suitable conditions on problem functions. Furthermore, the condition number of the Hessian of the nonlinear Lagrange function with respect to the decision variables is analyzed, which is closely related to efficiency of the algorithm. Finally, the preliminary numericM results for several typical test problems are reported.

关键词： nonlinear Lagrange algorithm general nonlinear constrained optimization problem solutionmapping multiplier mapping condition number.

Debris Flow Disaster Prevention and Mitigation of NonStructural Strategies in Taiwan

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2014年第2期11卷 308-322页

作者： CHEN su-Chin wu Chun-Yi Department of Soil and Water Conservation National Chung-Hsing University

Taiwan has disadvantageous conditions for sediment-related disasters such as debris flows. The construction of engineering structures is an effective strategy for reducing debris flow disasters. However, it is impossible to construct engineering structures in all debris flow areas in a short period. Therefore, the government aims to gradually develop non-structural preventive strategies, including evacuation planning, debris flow disaster emergency action system, disaster resistant community program, recruitment of debris flow professional volunteers, debris flow warning systems, and land management strategies, to mitigate disasters and secure the safety of residents. This review describes the processes and effects of recent debris flow non-structural preventive strategies in Taiwan. The average number of casualties prior to the year 2000 was far higher than the corresponding number after 2000 because debris flow evacuation drills have been promoted since 2000 and the debris flow disaster emergency action system has been progressively improved since 2002. Furthermore, the changes in risks caused by debris flow disasters before and after the implementation of non-structural preventive strategies were used to explain the effectiveness of these strategies at the community level. The results showed that softwarebased non-structural preventive strategies can effectively reduce the casualties caused by debris flows at both the national and community levels.

关键词： Debris flow Warning systems Evacuation planning Rainfall threshold Preventive strategies

Risk assessment method of major unsafe hydroelectric project

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2008年第9期51卷 1345-1352页

作者： wu ZhongRu su HuaiZhi GUO HaiQing College of Water Conservancy and Hydropower Engineering of Hohai University Nanjing 210098China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Nanjing 210098China

Based on the characteristics of major unsafe hydroelectric projects and the data from field detection, in situ monitoring, and regular safety inspection, the funda-mental principles of operation risk assessment are proposed in this paper. Mean-while, a three layer hierarchical system is constructed, and an improved analytical hierarchical process combining genetic algorithm and analytical hierarchical process is established, with corresponding program. The operation risk of some unsafe dam was assessed with the principles, method and program presented in this paper and the major factors which would affect the operation of the dam were pointed out.

关键词： major unsafe hydroelectric project operation risk analysis method

Path Classification and Estimation Model Based Prognosis of Pneumatic Cylinder Lifetime

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Mechanical Engineering 2012年第2期25卷 392-397页

作者： CHEN juan SONG Chunwen QI Xiaoye wu Wei School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China Aerospace System Engineering Institute Shanghai 201108China China Academy of Civil Aviation Science and Technology Beijing 100028China

Prognosis is a key technology to improve reliability,safety and maintainability of products,a lot of researchers have been devoted to this *** to improve the predict accuracy of remaining life of products has been *** predict the lifetime specification of pneumatic cylinders with high reliability and long lifetime and small specimen,this paper put forward the prognosis algorithm based on the path classification and estimation（PACE） *** model is based entirely on failure data instead of failure *** cylinders normally characterize with failure mechanism wear and *** the minimum working pressure increases with the number of working cycles,the minimum working pressure is chosen as degradation *** model is fundamentally composed of two operations：path classification and remaining useful life（RUL） *** classification is to classify a current degradation path as belonging to one or more of previously collected exemplary degradation *** estimation is to use the resulting memberships to estimate the remaining useful *** order for verification and validation of PACE prognostic method,six pneumatic cylinders are *** test data is analyzed by PACE *** is found that the PACE based prognosis method has higher prediction accuracy and smaller variance and PACE model is significantly outperform population based prognostics especially for small specimen *** model based method solved the problem of prediction accuracy for small specimen pneumatic cylinders＇ prognosis.

关键词： lifetime prognosis remaining useful life(RUL) path classification and estimation model Weibull distribution pneumatic cylinder

A Modified Residual-based Test for Serial Correlation in Linear Panel Data Models

在线全文

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2014年第2期30卷 401-410页

作者： Jian-hong wu Wei-hua su School of Statistics and Mathematics Zhejiang Gongshang University Zhejiang University of Finance and Economics Application of Statistical Science Research Center of Renmin University of China Key Research Institute

This paper suggests a modified serial correlation test for linear panel data models, which is based on the parameter estimates for an artificial autoregression modeled by differencing and centering residual vectors. Specifically, the differencing operator over the time index and the centering operator over the individual index are, respectively, used to eliminate the potential individual effects and time effects so that the resultant serial correlation test is robust to the two potential effects. Clearly, the test is also robust to the potential correlation between the covariates and the random effects. The test is asymptotically chi-squared distributed under the null hypothesis. Power study shows that the test can detect local alternatives distinct at the parametric rate from the null hypothesis. The finite sample properties of the test are investigated by means of Monte Carlo simulation experiments, and a real data example is analyzed for illustration.

关键词： panel data residual-based test serial correlation