Agricultural Productivity Changes Induced by the Sloping Land Conversion Program: An Analysis of Wuqi County in the Loess Plateau Region

This paper examines the agricultural productivity change induced by the Sloping Land Conversion Program (SLCP) using the Malmquist index method and household data collected from Wuqi. We find that during the period of 1998–2004, the total factor productivity (TFP) grew by 15.8%. While numerous households suffered a TFP decline, the majority of them experienced a large gain. By decomposing the TFP, we further show that its increase is due exclusively to the improvement of technical efficiency rather than to technological change. To validate these findings and put them in perspective, we also estimated the TFP change with county-level aggregate data. It is revealed that driven by technological change and scale efficiency, the TFP grew slightly during the period of 1992–1998. Because of the tremendous cropland reduction and production mode shift caused by implementing the SLCP, the TFP declined substantially during the first three years of the program; due to continued improvement of technical efficiency; however, its growth accelerated later. Altogether, our evidence consistently suggests that implementing the SLCP has contributed to the agricultural TFP growth in the longer term and that the efficiency improvement has resulted mainly from the increased public expenditures for extension services and diffusion of technical knowledge. Wuqi’s experience proves that it is possible to achieve environmental conservation and increase productivity simultaneously, even when facing a cropland reduction and production mode alternation.     

供水管网系统地震易损性风险评估

供水管网易损性风险评估就是通过识别和分析系统的易损性,找出管网中相对比较薄弱的部分,为确定安全策略和采取控制措施提供理论依据。借鉴网络脆弱性评估理论和方法,基于震后供水管网的连通性分析和水力分析结果,采用分层的分析方法,以管网的拓扑位置和节点服务特性作为影响管网易损性的因素,分配给各节点一定的权值,计算其易损性指标,采用定性与定量相结合的方法评判其易损性程度。对一实际管网进行地震易损性风险评估,说明了该方法的有效性与合理性。     

An Empirical Analysis of the Effects of China’s Land Conversion Program on Farmers’ Income Growth and Labor Transfer

In this article, we hypothesize that in addition to participation status and household characteristics, the impact of China’s Sloping Land Conversion Program on income growth and labor transfer is determined by local economic conditions, program range, and political leadership, and the degree of impact on income may vary among different economic sectors. To test these propositions, we have compiled a panel data set of 600 households in three counties in the Loess Plateau region, with observations for times both prior to and after the program’s inception (1999 and 2006), for both aggregate and categorical incomes, and for both participating and non-participating households. Using a difference in differences model and repeated cross-sectional data, we find that participation status, local economic conditions, program extent, and political leadership indeed have significant impacts on household income and off-farm employment. Moreover, the effects of participation on crop production income, animal husbandry income, and off-farm income vary substantially. These results carry major policy implications in terms of how to improve the effectiveness and impact of ecological restoration efforts in and outside of China.     

爆炸冲击载荷作用下双层钢板混凝土板与钢筋混凝土板动态响应对比研究

本文借助于通用显式动力分析软件LS-DYNA,采用流固耦合方法,分别对具有相同含钢量的双层钢板混凝土组合简支板和钢筋混凝土简支板两种结构在爆炸冲击载荷作用下的动态响应进行了数值模拟,其中空气和炸药采用ALE网格,简支板采用Lagrange网格,炸药采用JWL状态方程。通过对比分析,得到如下结果:在本文给定的计算条件下,当爆炸距离为0.5 m时,双层钢板混凝土组合简支板中心最大位移明显小于传统的钢筋混凝土简支板,具有更好的抗爆性;当爆炸距离增大到5 m时,两种简支板中心最大位移趋于一致;在爆炸冲击载荷作用下钢筋混凝土板下层出现明显的剥落,而由于钢板的约束,双层钢板混凝土组合简支板并未出现剥落现象。     

Evaluation and dynamic prediction of ecological security from the perspective of sustainable development: a case study of Shaanxi Province,China

Environmental Science and Pollution Research - How to measure the overall level of regional social economy, resources, and environment and how to grasp the coordinated development between them has...