关于公路与桥梁之间过渡段施工技术初探

本文主要分析了公路桥梁间过渡段出现不均沉降的原因以及公路桥梁间过渡段的施工技术的应用情况,此项技术对降低施工成本,提升桥梁的可靠性与安全性有重要作用。     

改进的沾滴法测量缓蚀剂预膜厚度

分析了传统沾滴法测量预膜厚度存在的问题,对原有的方法进行了改进,使用自制实验装置采用改进后的沾滴评价法测试分析了不同材质、不同管径管件的平均预膜厚度。结果表明,不同材质的管材表面吸附能力不同,导致管件平均预膜厚度相差较大,其中铜管的平均预膜厚度最大(0.05mm左右),碳钢管的平均预膜厚度最小(0.013mm左右);而管径对管件平均预膜厚度的影响很小。实验所得结果与同位素示踪法测定膜厚结果较吻合,从而说明改进后的沾滴评价法是一种室内评价管件平均预膜厚度的有效方法。     

Updating Input–Output Tables with Benchmark Table Series

Numerous methods have been proposed to update input–output (I–O) tables. They rely on the assumption that the economic structure will not change significantly during the interpolation period. However, this assumption may not always hold, particularly for countries experiencing rapid development. This study attempts to combine forecasting with a matrix transformation technique (MTT) to provide a new perspective on updating I–O tables. Under the assumption that changes in the trend of an economic structure are statistically significant, the method extrapolates I–O tables by combining time series models with an MTT and proceeds with only the total value added during the target years. A simulation study and empirical analysis are conducted to compare the forecasting performance of the MTT to the Generalized RAS (GRAS) and Kuroda methods. The results show that the comprehensive performance of the MTT is better than the performance of the GRAS and Kuroda methods, as measured by the Standardized Total Percentage Error, Theil's U and Mean Absolute Percentage Error indices.     

Rank-based Tests for Cross-sectional Dependence in Large (N,T) Fixed Effects Panel Data Models

Most existing methods for testing cross-sectional dependence in fixed effects panel data models are actually conducting tests for cross-sectional uncorrelation, which are not robust to departures of normality of the error distributions as well as nonlinear cross-sectional dependence. To this end, we construct two rank-based tests for (static and dynamic) fixed effects panel data models, based on two very popular rank correlations, that is, Kendall's tau and Bergsma–Dassios’ τ*, respectively, and derive their asymptotic distributions under the null hypothesis. Monte Carlo simulations demonstrate applicability of these rank-based tests in large (N,T) case, and also the robustness to departures of normality of the error distributions and nonlinear cross-sectional dependence.     

新零售下社区生鲜配送模式的综合评价

新零售模式下社区生鲜“最后500m”的冲刺已成为生鲜农产品快速配送的关键问题。基于目前已有的配送模式:“社区+便利店”模式、第三方配送以及众包模式,通过层次分析法从服务水平、配送成本、客户体验三个方面对三种配送模式进行量化分析,得出每种配送模式在各层次的权重。研究结果表明配送中降低配送成本是关键,减少货物赔损率、提高客户满意度才能实现有效率的配送。     

浅谈分离式立交满堂支架的受力验算

分离式立交在工程实际中应用广泛,施工中对满堂支架的强度、刚度、稳定性的要求较高,本文以某工程为例,验算该支架能否满足工程施工的要求。     

A new professionalism for agricultural research for development

There have been repeated calls for a ‘new professionalism’ for carrying out agricultural research for development since the 1990s. At the centre of these calls is a recognition that for agricultural research to support the capacities required to face global patterns of change and their implications on rural livelihoods, requires a more systemic, learning focused and reflexive practice that bridges epistemologies and methodologies. In this paper, we share learning from efforts to mainstream such an approach through a large, multi-partner CGIAR research program working in aquatic agricultural systems. We reflect on four years of implementing research in development (RinD), the program’s approach to the new professionalism. We highlight successes and challenges and describe the key characteristics that define the approach. We conclude it is possible to build a program on a broader approach that embraces multidisciplinarity and engages with stakeholders in social-ecological systems. Our experience also suggests caution is required to ensure there is the time, space and appropriate evaluation methodologies in place to appreciate outcomes different to those to which conventional agricultural research aspires.     

社会责任投资实证分析

与只考虑风险及回报的传统投资方式不同,社会责任投资在投资对象的筛选中,除考虑财务指标以外,还特别注重社会、环境、人权等企业社会责任的标准.传统的投资理念认为投资以追求财务回报最大化为唯一的目标,考虑财务回报以外的社会责任因素就会降低投资收益.在传统的投资组合的基础上构建关注利益相关者的社会责任投资模型,实证研究结果表明:社会责任投资意味着关注其他利益相关者不仅不会削弱投资回报率,而且具有高于市场的投资回报率.