Strategic tariffs, tariff jumping, and heterogeneous firms

The majority of research to date investigating strategic tariffs in the presence of multinationals finds a knife-edge result where, in equilibrium, all foreign firms are either multinationals or exporters. Utilizing a model of heterogeneous firms, we find equilibria in which both pure exporters and multinationals coexist. We utilize this model to study the case of endogenously chosen tariffs. As is standard, Nash equilibrium tariffs are higher than the socially optimal tariffs. Unlike existing models with homogeneous firms, we find that non-cooperative tariffs promote the existence of low-productivity firms relative to the socially optimal tariffs. This highlights a new source of inefficiency from tariff competition not found in models of homogeneous firms. In addition, we find that in many cases the Nash equilibrium tariff when FDI is a potential firm structure is lower than when it is not. As a result, FDI improves welfare by mitigating tariff competition.     

预制节段拼装预应力混凝土箱梁胶接缝抗剪性能研究

由于节段间接缝的影响,导致预制节段预应力混凝土箱梁接缝处抗剪机理与连续整跨梁存在较大差异,在计算抗剪承载力时无法直接应用整跨梁抗剪计算公式。首先对节段拼装箱梁接缝处的抗剪机理进行分析,得到影响计算抗剪承载力的关键参数;其次在已有计算公式的基础上,考虑混凝土立方体抗压强度和接缝处键齿数等参数的影响,提出适用于这种抗剪承载力的计算公式;最后将提出的计算公式与试验数据对比,表明该计算公式中的参数物理意义明确,计算精度较高,为预制节段拼装预应力混凝土箱梁结构的设计及应用提供了一定理论基础。     

Choose to Fight or Choose to Flee? A Network Embeddedness Perspective of Executive Ship Jumping in Declining Firms

Research summary: Executives in declining firms may engage in ship‐jumping behavior (i.e., voluntarily move to new employers before the failure occurs) to avoid the stigma of failure. However, it is unclear how executives decide whether or not to jump ship. Building on a network embeddedness perspective, we highlight how three network‐based indicators (i.e., executive social capital, the social capital of other peers in the declining firm, and the declining firm's alliance network) influence the executive‐level ship‐jumping decision by shaping its benefits and opportunity costs. Using data from executives at failing firms in China, we find support for our hypothesized relationships. Our research provides important insight into the network mechanisms driving the ship‐jumping decision. Managerial summary: Executives at failing firms have a choice: stay and attempt to rescue the firm from failure or exit and avoid the stigma of the failure (i.e., jump ship). Yet, little is known about what factors affect this choice. We propose that social capital plays an important role in the decision. Our evidence from specially treated (*ST) public firms in China finds that ship jumping is lowest at low and high values of social capital, and highest at moderate levels of social capital (an inverted U‐shaped relationship). In addition, higher levels of peer social capital (in the declining firm) as well as a well‐established firm‐level alliance network discourage the ship‐jumping choice. Copyright © 2017 John Wiley & Sons, Ltd.     

基于CenterNet的跑步姿态鉴别系统的设计

为了改善目前大众跑步姿势普遍不规范的现状,提出了一种基于CenterNet的跑步姿态鉴别系统。首先,通过截图、拍照的方式自制数据集,并对数据集进行清洗、标注和分析,消除数据无关信息与简化数据。其次,引入多尺度通道注意力机制与添加十字星变形卷积2种方式改进CenterNet算法模型,将动作图像转化为数字信息和特征向量,并以此为基础,利用KNN（K-nearest neighbors）算法对跑步姿态类型进行分类。最后,与经典模型方案进行对比,验证改进CenterNet算法鉴别系统的有效性。结果表明：改进的CenterNet模型的精确率与召回率都有所提升,其参数量与计算量降低。所提算法模型能够对大多数不良姿势作出及时、准确反馈,有效帮助跑步爱好者发现问题,从而改善跑步姿态、提高运动效率、预防伤病。     

高层结构施工应注意的几个问题

针对铜陵地区特殊的地质条件,文章就高层建筑地下室地基土方施工应注意的问题,以及本地区高层建筑施工中混凝土施工缝留设、地下室混凝土壁板抗渗、钢筋施工、混凝土界面处理等方面常见的问题及处理措施进行了分析。     

谈公路工程桥头跳车的产生原因及防范措施

目前,在我国公路工程施工中,桥头跳车的现象普遍存在。文章对公路工程桥头跳车问题产生的原因进行分析,并制定出相应的防范措施,以达到降低桥头跳车现象发生的频率及减少桥头沉降程度之目的。     

高拱坝的抗震设计分析及抗震措施研究

本文对高拱坝坝体工程的抗震设计进行了分析，其中对高拱坝抗震设计的基本理念，高拱坝的抗震设计方法，以及高拱坝坝体工程的抗震措施研究这几个方面做了一系列的分析及总结。     

激光点焊技术在通风槽板制造中的应用

本文主要介绍激光点焊技术在大型电机通风槽板加工过程中的应用,分析了激光点焊中主要加工参数对焊接质量的影响。并对现有通风槽板的几种加工工艺方法进行分析和比较。     

螺栓设计的假想危险截面面积法

本文介绍了一种设计普通螺栓直径的简便方法。并运用数值分析方法对大量数据进行电算,制作成表,供人工手算时使用。     

关于桥梁伸缩缝的施工与质量控制问题探讨

伸缩缝是桥梁构造中的重要组成部分,由于长期暴露在大气中,是桥梁结构中最易受损部位。加强桥梁伸缩缝的施工与质量控制直接关系到车辆安全及桥梁的使用寿命。因此,本文通过分析桥梁伸缩缝的种类,针对其施工方法与质量控制问题进行探讨。以期通过本文的阐述为确保桥梁伸缩缝的质量提供理论依据。