Regulation of relationships between heterogeneous farmers and an aquifer accounting for lag effects

Many environmental problems are due to damage caused by pollutants that accumulate with a time lag following their emission. In this study, we focus on nitrates used in agriculture, which can pollute groundwater many years after their initial application. A dynamic optimal control problem with heterogeneous farmers is proposed. The usual structural parameters such as the discount rate, the natural clearing rate and the lagged time interval between the occurrence of soil‐level pollution and the impact on groundwater are taken into account. We also examine pollution as caused by a continuous set of farms characterised by their individual performance index and by their individual marginal contribution to the pollution. The issue is further investigated by taking account of change in the information context, successively related to perfect information and to asymmetric information. As a result, when the delay between the spreading of N‐fertilizer and the impact on the aquifer increases, that is, the longer the lag, the steady‐state pollution stock and the steady‐state shadow price of the stock both increase. Moreover, we show that the optimal regulation may require a decreasing amount of fertilizer over time, even in the case of initial underpollution.     

Dress for success: the effect of exhibitors’ dress conformity and self-construal on attendees’ approach behavior

ABSTRACT

The purpose of the current study is to investigate how attendees’ approach behavior is influenced by exhibitors’ dress conformity. A 2 × 2 between-subjects quasi-experimental design was utilized for this study. Our results showed that conforming dress for exhibitors can lead to a higher level of approach behavior of trade show attendees as compared with nonconforming dress, and the effect of exhibitors’ dress styles on approach behavior is moderated by attendees’ self-construal. Findings of this study provide significant insights for trade show exhibitors and attendees.     

基于模态应变能密度理论的网架结构损伤识别方法

为了研究网架结构的损伤检测方法,根据应变能密度理论,提出采用单元模态应变能密度差值作为网架结构损伤识别指标的方法,以损伤单元模态应变能密度差值的大小初步确定单元的损伤程度。分析了5种具有代表性的损伤工况,并在数值计算结果中引入了白噪声。结果显示,在一阶模态下,针对单损伤、多损伤和轻微损伤、严重损伤等不同损伤工况,损伤杆件的模态应变能密度差值均为高值。因此,该方法可以有效识别出网架结构的损伤位置,根据损伤单元的模态应变能密度差值大小初步确定单元的损伤程度,且在一定的噪声水平下具有较强的鲁棒性,对网架结构损伤识别具有参考价值。     

城市故事论--一种后现代城市设计的建构性思维

以城市故事的概念来建立一种后现代城市设计的建构性思维,分析城市意义要素类型和营构特性,追求城市的整体生态价值以及环境的公正价值观.研究城市故事空间的的系统性、多元性、深层性和差异性,强调对自然生态系统、人类历史文化以及市民空间行为的重视.     

Research agenda for low-carbon mobility: Issues for New World cities

ABSTRACT

Low-carbon mobility (LCM) features strongly in debates about the sustainability of cities and their resilience in the face of demographic, economic, and climate change. Transport is a major source of carbon emissions and there are indications that these continue to increase, despite the considerable recent advances in vehicle, engine, and fuel technologies. Reducing carbon emissions from transport may become more difficult, not easier. A particular issue relates to the New World cities, typified by those of North America and Australasia, which largely developed from the latter half of the nineteenth century onward and whose transportation systems were largely based around private vehicle ownership and usage. These cities are typically composed of low-density, dispersed suburbs, which are highly car dependent and resource and carbon emission intensive. This article develops a research agenda directed at determining and testing policy and planning measures relevant to the quest for low carbon mobility in New World cities. It suggests a rich agenda for essential research on LCM. Much of this agenda falls within the realm of the integration of transport and land use, with attention to urban design details to enhance the perceptions of and opportunities to use low carbon transport alternatives. Research topics identified for LCM research include (1) urban design and land use–transport integration (LUTI), (2) low carbon mobility policies directed at achieving widespread behavior change, (3) opportunities for new technology and its application, including requirements for systems and infrastructure, and (4) analysis and tools for informed decision making, including modeling, measurement, visualization, and especially assessment.     

Product variety,sourcing complexity,and the bottleneck of coordination

Research summary: This paper studies the coordination burden for firms that pursue variety as their main product strategy. We propose that product variety magnifies the tension between scale economies in production and scope economies in distribution, giving rise to complex sourcing relationships. Sourcing complexity worsens performance and poses a dilemma for organization design: A hierarchical structure with intermediate coordinating units such as sourcing hubs reduces sourcing complexity for downstream distribution but creates bottlenecks at the hubs, hurting performance for both the hubs and downstream distribution. We empirically examine operations data for about 300 distribution centers within a major soft drink bottling company in 2010–2011. Results support our hypotheses, illuminating the source of complexity in multi‐product firms and the challenge for organization design in managing complexity. Managerial summary: This paper uses data for about 300 distribution centers within a major soft drink bottling company to study how a large product variety creates complex sourcing networks. We find that, in addition to poor performance (e.g., increased stockouts), complex sourcing networks can cause challenges for organization design. In particular, the benefits of converting an existing distribution center into a sourcing hub (i.e., reduction in sourcing complexity for downstream distribution) and the costs of doing so (i.e., reduction in performance for both the hubs and downstream distribution) are both real and significant. The design of an efficient sourcing network despite its complexity involves important managerial decisions. Experiences in building and managing such networks can be the basis of a dynamic capability. © 2016 The Authors. Strategic Management Journal published by John Wiley & Sons Ltd.     

Environmental scanning the future of event design

This paper used multiple sources of information in order to identify the forces likely to impact event design. Content analysis of key informant interviews and selected trade publication articles identified key forces impacting event design. Technology, the environment and green issues, security and safety, and globalization were forces identified by both the key informants and the trade literature. Neither of the sources gave much attention to political forces. This article contributes to our understanding of the forces impacting event design and suggests some environmental scanning methodologies that can be used with both key informants and the trade publication literature.     

复杂海域环境下钢栈桥的设计与验算

沿海路改桥项目施工过程中常规的施工便道及施工平台无法满足桥位处复杂的海域环境要求,而复杂海域环境下钢栈桥结构常年经受大风及波浪冲击作用,结构受力复杂,需要进行特殊设计与验算。本文在已有研究成果的基础上设计了复杂海域环境下钢栈桥搭建方案,考虑钢栈桥在正常使用和台风期停工两种施工情况,采用Midas/Civil建立钢栈桥有限元分析模型,进行了多种典型工况下主要构件应力、钢管桩桩底反力及钢管桩嵌固点的验算。验算结果表明设计的钢栈桥满足项目施工要求,作为临时通道能够有效的解决桥梁的施工作业问题,对复杂海域环境下钢栈桥的设计与验算具有借鉴意义。     

一款移动式仓库上货椅梯的设计及分析

针对目前仓库货物取放工作效率低、劳动强度大且存在安全隐患等问题,本文借鉴传统的椅子及梯子的结构及功能,基于组合创新方法创新设计一种移动式仓库上货椅梯。该装置将椅子和梯子的功能合为一体,移动方便且稳定可靠,成功解决梯子靠在货架上易将货架压倒、椅子的高度不够、稳固性差、梯子及椅子搬运不便、移动性差等问题,提高了仓库取放货物的工作效率,应用推广前景广阔。     

浅谈EPC设计管理中的制度管理

近年来,由于国家政策支撑,“大力推行工程总承包,促进设计、采购、施工等各阶段的深度融合”,建筑行业出现大量EPC总承包工程,其中设计管理作为EPC工程项目管理中必不可缺的一环,与项目建设息息相关。本文主要研究了EPC设计管理制度建设的背景及原因,并对设计管理制度建设中存在的问题进行分析,探讨相应优化措施,提出相关建议。实际项目通过建立完善的设计管理制度后,对于EPC设计管理及项目管理起到了积极的作用,提高了EPC工程总承包项目设计管理水平。