多孔连续斜交框架桥顶进施工过程受力分析

城市道路下穿铁路框架桥顶进施工的关键是合理控制桥梁主体结构的受力。为了对框架桥顶进施工过程进行受力特性分析，采用Midas有限元软件模拟了框架桥在滑板上开始顶进、框架桥重心即将离开滑板、框架桥顶进即将就位三个施工阶段。结果表明，该框架桥的施工过程是安全可靠的，同时结合工程项目实际给出了顶进施工的注意事项。该方法可用来指导类似工程顶进施工过程的受力分析和施工控制。     

剖线强度梯度变化的作物软硬变化区精确划分

[目的]软硬变化区的划分是进行遥感变化检测技术识别农作物的基础。为解决人工判读方法中存在人为主观因素影响以及自动判别和交互式判别方法对不同研究区的适用性问题,该文提出基于剖线梯度变化(Profile based Gradient Change Magnitude,PGCM)进行软硬变化区划分的方法。[方法]该研究选择破碎农业景观种植区域为研究区,计算拔节期Quick Bird影像和播种期模拟影像两个时相的变化强度,从作物地块内部向外绘制剖线,利用剖线强度的梯度变化确定硬变化区(Hard change region,HCR)、软变化区(Soft change region,SCR)和未变化区(Non change region,NCR)3者间的划分阈值。[结果]从识别结果来看,PGCM能够有效在地块边界处探测到软变化像元,进而确定HCR、SCR。像元分辨率在5~60 m不同尺度下,识别HCR区混入比例为11%~16%,混入比例随着分辨率下降而降低;NCR区混入比例为3%~4%,受分辨率尺度影响不大;SCR区识别比例为74%~86%,识别精度较高,识别结果与冬小麦空间分布结果保持一致。[结论]PGCM方法能够自动、便捷地确定阈值,摆脱人工判定的主观性,有效地划分出HCR、SCR和NCR 3个区域,为进一步HCR、SCR区内的作物识别提供基础。     

Risk assessment for public–private partnership projects: using a fuzzy analytic hierarchical process method and expert opinion in China

Public–private partnerships (PPP) have been widely used in China to procure public facilities and services. Complicated problems in PPP projects in China arise because of a variety of risk factors. A proper risk assessment model is needed to identify risks and provide risk response strategies for future Chinese PPP projects. The fuzzy analytic hierarchy process (F-AHP) method provides the ability to solve complex risk assessment of PPP projects. Current risk assessment models are limited to PPP projects in specific countries and do not consider unique risks in China, especially political, economic, social, and legal risks. This paper designed a risk evaluation index system for PPP projects based on the Delphi expert investigation method, and then established an optimized risk evaluation model for PPP projects in China using the F-AHP method. The risks identified are confirmed by interviewing experts from Chinese local government departments, private enterprise, third-party intermediary consulting and regulatory agencies, and academic organizations. The results show that the risks that ranked among the top ten are closely related to China’s political and economic policies and relationships among stakeholders. It can be concluded that government authorities play a critical role in providing a favorable political, social, and economic environment and an effective institutional framework for PPP projects. Furthermore, it is also important to deal with relationships among stakeholders based on the public–private ‘win–win’ principle. This study provides risk response strategies, addressing key issues from eight aspects: an impeccable legal and regulatory framework; a central coordinating and regulating PPP authority; supportive governmental authorities; institutional capacity-building; favorable economic conditions and viability; community, partner, and moral accountability; clear division of responsibilities through contracts; and effective advisory management. These effective measures may be useful in reducing the adverse effects of risk for PPP projects in China.     

基于熵权Topsis的淮河生态经济带水资源承载力评价

[目的]评价发展规划驱动下的水资源承载力特征,为区域发展提供科学依据。[方法]以淮河生态经济带为对象,采用熵权重的Topsis评价方法,分析淮河生态经济带水资源承载力的区域差异及其影响因素。[结果] 2015年不同市县水资源承载力综合得分介于0. 305 8～0. 698 8之间,其中盐城市最高,桐柏县最低;境内江苏、安徽、河南3省的水资源承载力分别为0. 585 2、0. 478 2、0. 524 9。[结论](1)淮河生态经济带水资源承载力具有在淮河干流上、下游承载力高,但中游偏低的空间分布特征。(2)水资源系统层面,水资源总量是承载力高低的供给侧决定性因素,是水资源承载力高低的重要基础。(3)社会系统中,用水量与用水结构是提升和优化水资源承载力的调控性因素。(4)城镇化发展与人口增加是水资源承载力高低的胁迫性因素,而经济发展水平是水资源承载力调控的重要保证。     

湖南省农业生态与农业经济耦合性测度

[目的]考察湖南省近9年来农业生态与农业经济系统耦合发展现状,探究二者发展过程中的规律,以期找出二者协调发展模式,并为湖南省农业生态环境保护、农业经济发展提供决策依据。[方法]运用耦合协调度模型,基于熵权法为各指标进行客观确定权重,结合2007~2015年湖南省农业生态与农业经济发展的相关数据,确定农业生态与农业经济的耦合匹配分析模型,采用熵值赋权法确定各项指标的权重,构建农业生态—农业经济耦合协调评价指标体系。[结果]研究结果表明,2007~2015年湖南省农业生态与农业经济的耦合协调发展基本稳定,耦合度值均在0.9以上,二者呈协调发展趋势。其中,2014年和2015年二者的耦合度较高,分别为0.975 3和0.984 3,说明湖南省在这两年的农业生态与农业经济的协调性好,农业经济与农业生态能够相互有效促进彼此的发展。同时,仍需时刻关注生态环境的承载力,降低对自然资源的无序攫取,实现经济的可持续发展。     

Inconvenience cost of mobile communication failure: The case of South Korea

Mobile communication failure can occur when mobile traffic exceeds the manageable level. This depends on frequency bandwidth. Mobile communication failure causes inconveniences in a user's daily life that lead to social and economic damage. To address this issue, mobile telecommunications companies deploy additional bandwidths and develop new technologies, but these are costly strategies. This study applies a spike model based on a contingent valuation method (CVM) to measure the inconvenience cost resulting from mobile communication failure. The mean monthly willingness-to-pay (WTP) to avoid communication failure per user is estimated to be KRW 898.14 (USD 0.80) over a period of five years in our study. The inconvenience cost borne by the population is estimated to be KRW 2.97 trillion (USD 2.61 billion). Users experiencing greater frequency of communication failure are found to be willing to pay more to avoid the inconvenience. When excluding respondents citing zero-WTP, the mean WTP per user was calculated to be KRW 3426.41 (USD 3.01). Data traffic usage and frequency at which communication failure is experienced are variables that exhibit statistically significant effects on WTP to avoid mobile communication failure. Overall, estimation results show that a price discrimination based on data traffic usage or quality can be considered by mobile telecommunications companies and regulators to address the issue of data traffic inducing mobile communication failure.     

Effects of individual resources and team-member exchange on service quality

While workplace resources are generally viewed as positively affecting performance, some studies indicate that not all resources increase performance. This study addresses the controversial disparate effects of workplace resources on performance by exploring functionally classified workplace resources in self-managing service teams and their relative impacts on team service quality. Considering membership dynamics and consequences between members, a field experiment was conducted in a cafeteria, with data collected through a working diary for workplace resources and a customer survey to evaluate service quality. Results suggest that efficacy-resources in self-managing teams should be controlled with caution as they may adversely affect team service quality. Supporting the person–situation interactionism perspective, workplace resources interact dynamically with individual employees and with situations. Esteem-resources were found to increase team service quality, while team-member exchange not only improved team service quality but also moderated the impact of esteem-resources on team service quality.     

乌蒙山片区绿色减贫指数分析

[目的]通过分析2012年和2014年乌蒙山片区绿色减贫指数,评价该地区不同年份扶贫效果,这也为今后各项扶贫政策的实施提供理论参考。[方法]文章依据中国绿色减贫指数指标体系,从经济增长绿化度、资源利用与环境保护程度、社会发展能力和扶贫开发与减贫效果4个方面,以人均地区生产总值、单位地区生产总值能耗等27个因子作为评价指标,利用线性加权综合法分析2012年和2014年经济增长绿化度、资源利用与环境保护程度、社会发展能力和扶贫开发与减贫效果指标值,最终确定绿色减贫指数。同时,分析片区内各贫困县波动较大的第三产业增加值比重、单位耕地面积化肥施用量、城乡收入比和农村人均纯收入增长率等指标。[结果]2014年相比2012年,乌蒙山片区经济增长绿化度、资源利用与环境保护程度和扶贫开发与减贫效果指标值上升,社会发展能力指标值降低,绿色减贫指数提高了15.40%。各县第三产业比重均降低,但农村人均纯收入都有提高。四川省10个县单位耕地面积化肥施用量增加。四川省除叙永县和美姑县,贵州省除赤水市,片区内的各贫困县城乡收入比降低。[结论]2014年,乌蒙山区在落实国家扶贫规划上取得了较好的成效。但各县之间差距较大,在今后的扶贫攻坚中,需要从不同地区的实际情况出发,了解贫困类型和贫困程度,考察当地资源储备和环境现状,统筹区域发展。     

Quality of Corporate Social Responsibility Disclosure and Cost of Equity Capital: Lessons from China

This article explores the relationship between the quality of corporate social responsibility (CSR) disclosure and the cost of equity capital by analyzing the financial data and CSR reports of A-share listed firms in China from 2008 to 2014. The quality of the CSR disclosure is shown to be negatively related to the cost of equity capital of the listed firms. This negative correlation proves to be more prominent among firms of environmentally sensitive industries. Taking the ownership of the listed firms into consideration, it is further confirmed that the negative relationship between the CSR disclosure and the cost of equity capital is of higher significance for state-owned enterprises. Our findings also empirically demonstrate that the quality of CSR disclosure is more negatively related to the cost of equity capital among the large listed firms than the smaller ones.     

An examination of the effects of 2014 concealed weapons law in Illinois on property crimes in Chicago

The purpose of the present study is to determine the effects of ‘may issue’ Concealed Carry Weapons (CCW) law implemented in early 2014 in Chicago. Based on the daily community-level crime data from January 2006 to December 2015, using zero-inflated negative binomial difference-in-difference specification with Philadelphia as the control group, the property crimes in Chicago declined after the implementation of ‘may issue’ CCW law. The findings are robust to alternate treatment windows and to a placebo test using time windows before implementation of the law.