天津市美丽乡村建设模式及效益评价体系构建

［目的］“美丽乡村”建设是全面推进现代化农业发展，加强生态文明建设的重要举措。归纳天津市“美丽乡村”建设模式，构建效益评价体系，并对乡村建设效益进行评价，以期为实现该市乡村建设奋斗目标提供理论参考。［方法］通过调研天津市乡村发展现状，在归纳总结该市乡村建设模式的基础上，采用层次分析法和综合加权法，从社会、经济和生态效益3个层面构建了美丽乡村建设效益评价体系，并对“美丽乡村”建设项目实施前和2016年的建设效益进行评价。［结果］（1）天津市乡村建设模式可分为4种类型，分别为休闲旅游、文化传承、高效农业和环境整治型，涌现出了一批各具特色的典型村落，发展较为迅速。（2）从启动美丽乡村建设项目止2016年，该市乡村建设取得了明显的生态、社会和经济效益，评价分值相比项目实施前分别提高了6513%、4167%和3621%，综合效益评分提高了50%。［结论］天津市美丽乡村建设取得了较好的成效，其他村庄在建设过程中，可参考已建设成型的典范，因地制宜，选择适合规划的发展模式。已建设成型的村庄发展空间还很大，仍需不断缩短城乡差距，推动美丽乡村的可持续健康发展。     

基于PSO的信息熵数据融合非均匀分簇路由算法

针对无线传感器网络分簇算法中能量分布不均衡导致的"热区"和簇头负载过重问题,提出了一种基于PSO算法优化簇头选举的非均匀分簇算法。在候选簇头选举和竞争半径计算过程中综合考虑节点动态能量、节点密度和节点距基站距离,将网络进行非均匀分簇,并引入PSO算法进行最终簇头选举。根据节点能量、节点密度和距基站距离确定簇间单跳多跳结合的路由规则,选取代价函数小的节点作为下一跳节点。基于节点信息熵确定融合阈值,进行簇内数据融合剔除冗余数据。仿真结果表明,改进算法的数据传输量比EEUC算法和UCRA算法分别提高了20%和10%,提升了数据的融合效率,有效延长了网络生命周期,簇头能量消耗得到均衡,减少了网络能量消耗,网络的整体性能显著优于其他对比算法。     

基于DEA模型的建筑业环境行为效率评价研究

对建筑企业进行环境行为效率评价是促进我国建筑行业健康可持续发展的重要手段。根据建筑行业特点及我国现有的企业环境信用标准,构建了建筑企业环境行为评价的投入产出指标体系,将改进的数据包络分析方法模型运用到企业环境行为效率评价领域,解决了现有企业评价研究主观性突出的问题,得出建筑企业评价分析方法。在此基础上对某代表性建筑企业2010—2017年环境行为数据进行了评价分析。分析结果表明该企业环境行为总体效率良好,但鉴于出现了奇数年和偶数年的效率波动情况,仍需提高环境行为效率。     

Evaluation of workplace lactation support among employers in two Pennsylvania cities

A majority of mothers with infants less than 1 year old participate in the labor force. Employers can modify the physical and social environments at work to accommodate breastfeeding employees and enable continued participation in the labor force. The purpose of our article is to (1) characterize breastfeeding policies and programs currently offered at workplaces in two Pennsylvania cities and (2) identify improvement areas to support breastfeeding employees in the workplace. We partnered with two business groups on health in Pennsylvania and electronically administered a survey to their employer members. Responses were aggregated into a workplace lactation support score based on physical space, time, policy, and resources. Higher scores indicate that employers offered a large number of workplace lactation supports. We conclude by offering specific improvement opportunities that include a written policy communicated to all employees and the formal communication of lactation services. Employers can utilize workplace lactation support scores to elect interventions that are feasible for implementation in their organizations.     

协调度视角下长江流域产业转移效率研究

实现区域经济协调发展是当前我国在块集聚与点极化双重压力下面临的现实难题，长江经济带尤其是欠发达省份承接发达地区产业转移是解决该难题的必然路径选择。产业转移活动因区域主客体特征变量不同，呈现出典型的多发式转移和门槛转移特征，使得区域政策制定缺乏科学指导，陷入盲目拼政策红利的状态。结合效率模型及考虑熵权的经济社会发展协同度分析，测算了2004-2016长江经济带各省（市）年综合产业转移效率，并考察了门槛效应值及变化趋势。结果表明：在考察期内，长江经济带各省（市）产业转移效率提升较为明显，但不少省（市）存在不协调的阶段性平衡关系，且这种关系还未显露经济总量驱动下的协同发展能力。     

全球价值链下中国增加值贸易的核算及网络特征研究

基于投入产出模型和社会网络分析，利用世界投入产出表相关数据，对2000—2014年中国的增加值贸易进行核算，并分析全球增加值贸易的网络特征。研究结果显示：（1）从出口目的地来看，中国向美国、日本、德国等国家的增加值出口较大；（2）从行业来看，中国的纺织业、除汽车和摩托车之外的其他产品批发业、采矿业等行业的增加值出口较大；（3）根据网络密度的计算结果，世界范围的各国（地区）贸易联系程度在增强；（4）中国的相对点度数和点强度有上升的趋势，而日本和美国有下降的趋势，说明中国在世界增加值贸易格局中的地位在提升，不过美国仍在世界增加值贸易格局中占据主导地位；（5）核心边缘分析结果表明核心国家（地区）的数目经历了先增加后减少的过程，边缘国家（地区）数目则先减少后增加。其中，中国的核心度一直在增加，日本和美国的核心度呈现下降的趋势。因此，为了扩大增加值贸易，增强国际贸易的话语权，中国政府有必要采取调整进出口税率等政策，并重视与美国等国家的双边贸易合作，以实现双赢的结果。     

Do ongoing networks block out new friends? Reconciling the embeddedness constraint dilemma on new alliance partner addition

Research Summary: This study addresses a theoretical dilemma regarding how alliance network constraint (reflected by network cohesion) affects a firm’s alliance formation with new partners. Using a network pluralism approach, we separate a firm’s ego alliance network into two activity‐based networks—an exploratory network and an exploitative network—based on the primary value chain activity involved in each alliance. We argue that the cohesion of exploratory or exploitative networks has an inverted U‐shaped effect on the addition of new partners in the same activity‐based network, and a positive effect on the addition of new partners in the other network. Results based on data from the biotechnology industry largely support our predictions with one exception. Our study contributes to both scholarly understanding of network embeddedness and alliance practice. Managerial Summary: The structure of firms’ ongoing alliance networks may have paradoxical implications for their efforts to search for and form alliance with new partners. That is, when a firm’s alliance partners are tightly connected with each other, the cohesive network tends to both encourage and impede the focal firm to add new partners. We resolve this dilemma by showing that when a firm is deeply entrenched in a cohesive alliance network conducting a certain type of activities (e.g., R&D activities), it may not easily add new R&D alliance partners. However, it may still be able to escape from the cohesive R&D alliance network by seeking new partners conducting other activities (e.g., manufacturing activities).     

Size and value effects in high-tech industries: The role of R&D investment

We use monthly US stock data over 55 years from 1962 to 2017 to show that the R&D intensity at firms adds another important dimension to the size and value effects in describing stock returns, especially for small high-tech firms. A trading strategy that double sorts on R&D intensity and size or book-to-market ratio outperforms a simple small-minus-big (SMB) or high-minus-low (HML) strategy in producing higher and more significant portfolio returns. The most profitable schemes involve triple sorts by size, BM, and R&D intensity: the payoffs of buying high-BM/R&D-Active portfolio and selling low-BM/R&D-Inactive portfolio in the small-size/high-tech group and that of buying high-tech/high-BM and selling low-tech/low-BM in the small-size/R&D-active group generate a return of more than 2% on a monthly basis. Our results are robust to alternative classification method of assigning stocks in portfolios.     

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。