水下高速气体射流的实验研究

本文对高速空气射流在受限约束下的动力学行为进行了实验研究。通过流动可视化揭示了高速空气射流在单筒和同心筒发射筒底部滞止、反转、而后向上绕经航行体或同心筒间隙向上喷入水中的演化过程。主要观察了单筒底部有无导流锥、同心筒三种间隙在不同压比和不同流量下的气水两相流态,并测量了航行体与发射筒的壁面压力分布。给出了航行体壁表面压力的动态变化规律,和沿轴向的分布规律。     

Value creation in innovation ecosystems: how the structure of technological interdependence affects firm performance in new technology generations

The success of an innovating firm often depends on the efforts of other innovators in its environment. How do the challenges faced by external innovators affect the focal firm's outcomes? To address this question we first characterize the external environment according to the structure of interdependence. We follow the flow of inputs and outputs in the ecosystem to distinguish between upstream components that are bundled by the focal firm, and downstream complements that are bundled by the firm's customers. We hypothesize that the effects of external innovation challenges depend not only on their magnitude, but also on their location in the ecosystem relative to the focal firm. We identify a key asymmetry that results from the location of challenges relative to a focal firm—greater upstream innovation challenges in components enhance the benefits that accrue to technology leaders, while greater downstream innovation challenges in complements erode these benefits. We further propose that the effectiveness of vertical integration as a strategy to manage ecosystem interdependence increases over the course of the technology life cycle. We explore these arguments in the context of the global semiconductor lithography equipment industry from its emergence in 1962 to 2005 across nine distinct technology generations. We find strong empirical support for our framework. Copyright © 2009 John Wiley & Sons, Ltd.     

论垂直价格挤压下的接入定价规制

在自然垄断产业引入竞争的过程中,独占传输网络的纵向一体化垄断厂商可能对下游市场新进入者实施接入价格挤压。接入价格挤压从属于价格歧视。尽管一定条件下的接入价格挤压具有正向的竞争效应,但垄断厂商将具有同等效率或更高效率的独立厂商驱逐出市场则应该受到规制。接入价格规制包括政府直接规制定价和反垄断法间接规制定价。直接规制定价中整体价格上限较为可取,而反垄断法间接规制需要采用基于福利后果分析的合理推定原则,但从短期来看采用直接规制更有效率。最后提出了完善我国自然垄断产业接入定价规制的相关政策建议。     

The impact of vertical integration on inventory turnover and operating performance

This paper investigates how vertical integration may influence inventory turnover and firm operating performance. A causal model is developed to investigate the effects of vertical integration on three types of inventory, namely raw materials inventory (RMI), work in progress inventory (WIPI) and finished goods inventory (FGI). The model tests the interactions between inventory types and the consequences of inventory turnover performance on various aspects of firm performance including costs and profitability. In particular, path analysis supports systematic differences with respect to how vertical integration affects RMI, WIPI and FGI. Vertical integration has a positive effect on RMI and FGI turnover but no significant effect on WIPI turnover. FGI contributes to a reduction in supporting processes costs which causes an improvement in return on sales (ROSs). Vertical integration impacts ROS directly.     

北京市现代职业教育体系建设中的纵向衔接问题研究

构建纵向衔接与横向沟通的现代职业教育体系是国家职业教育发展的一项重大战略决策。纵向衔接是建设现代职业教育体系的基础,是搭建不同类型教育与培训“立交桥”的前提。基于北京市现代职业教育体系建设中纵向衔接问题的调查与分析,提出了要以培养学生职业能力为主线,以专业衔接为依托,以课程体系建设为手段,加强现代职业教育体系建设中的纵向衔接。     

铰链门垂直刚度探析

铰链门的设计要素及评价指标较多,其中最重要的要素是垂直刚度指标。垂直刚度指标的确立及研究对车门设计具有指导意义。文章重点阐述了垂直刚度的分析方法及指标。     

一种基于有限元计算的半挂车强度分析

用有限元计算方法对某型半挂车车架的强度进行了分析计算。通过有限元仿真计算,提出在进行局部加强的同时,采用细而密的横梁结构的优化方案,解决了原来结构的应力集中现象,确保半挂车的结构强度。     

风神汽车焊装车间设备基础梁板脚手架施工方法

焊装设备基础构件大,梁板柱结构复杂,脚手架支设为工业厂房建设中较为复杂的土建施工的代表。文章通过介绍焊装设备基础脚手架的设计与施工,为此类工程的脚手架设计施工提供参考。     

中日制造业双边贸易核算——基于贸易附加值的分解

随着国际生产链条的不断延伸以及中间产品生产的多次跨国境变动,越来越多的国家参与到中日双边制造业贸易收益分配中。基于世界投入产出数据库1995—2009年的相关数据,采用将双边出口贸易分解成16部分的核算方法,基于贸易附加值的分解核算中日两国制造业双边贸易。结果显示两国制造业出口的国内附加值绝对额均不断上升,两国的垂直专业化率均不断提高。两国应以推动中日韩建立区域全面经济伙伴关系为契机,积极融入全球价值链分工体系。     

纵向分离能否提高企业全要素生产率?——基于电力产业"厂网分开"的研究

中国电力行业一直延续纵向分离的改革路径,继发电环节从一体化垄断结构中分离之后,2015年新一轮的电力体制改革又提出输配售电业务分离、推进电力市场化交易的目标。不同纵向结构下,电力产业链上下游企业的博弈均衡显示纵向分离改革可提高上游发电环节的竞争性,减少效率损失。进一步基于微观发电企业数据,通过双重差分及倾向得分匹配模型考察“厂网分开”这一准自然实验的效果,研究结果显示,纵向分离改革显著提升了发电企业的效率。现阶段应继续推进输配售分离改革,通过供给侧和需求侧的互动响应使上游发电环节的效率收益纵向传递,提高消费者福利。