弧形封闭管道断面流速模型研究

对于弧形封闭管道的紊流速度分布研究也是基于圆形断面管道紊流的理论基础之上,并且结合一定的假设来数值模拟弧形封闭管道的紊流速度分布规律。通过大量的实验证明本文的研究方法及程序较好的模拟了弧形封闭管道的紊流速度分布情况,为下一步研究淤积管道的解决方法提供了理论依据。     

V型墩刚构桥合拢段施工技术

宜春明月大桥工程采用V型墩与连续箱梁刚性连接形成V型墩刚构桥。该连续刚构桥构造复杂,且受施工环境因素制约,增加了该桥施工难度。本文结合宜春明月大桥实例,详细阐述V墩刚构箱梁合拢段的施工工艺和技术要点。     

浅谈煤矿企业的地区保卫科班组建设

班组是企业的基本生产单元,是一切工作的落脚点和出发点,班组情况的好坏直接关系到企业的活力。班组建设并不是一个新话题,但是为了促进企业的更好发展,必须加强班组建设,从而充分发挥班组的导向、激励和凝聚作用,充分体现班组职工的奋发向上、自觉自主的相互学习、相互提高的作用。本文通过煤矿企业的地区保卫科班组建设,谈谈一些认识,目的是使企业的班组和班组职工在业务技能、服务规范、工作态度等方面都有改善,从而促进企业的班组和班组职工工作素质水平有更大幅度地提高。     

大微客尾门铰链加强板设计探讨

文章结合上汽通用五菱汽车股份有限公司多款车型的尾门加强板设计经验,介绍了大微客尾门铰链加强板设计的一些经验和想法,论述了上汽通用五菱汽车股份有限公司某款车型试制阶段出现的一些加强板焊点开裂问题及相应措施。在此做一个总结,为同行在尾门加强板的结构设计方面提供参考。     

浅谈10kV配电设计

一般情况下,按变压器的效率最高时的负荷率βM来计算变压器容量,计算负荷最好是2倍总功率P总,留有一定的缓冲空间,而母线采用的材料为铜、铝、钢或其他金属。电缆绝缘材料应根据电缆绝缘材料的种类来选用,电缆截面的选择应特别注意电缆允许载流量与敷设环境的温度。     

京石客专悬浇梁合龙段施工中劲性骨架的应用

悬浇梁合龙段施工所涉及到的工艺繁琐,其中劲性骨架施工是合龙段施工的关键环节。本文结合京石客运专线牛家堡48+80+48m现浇预应力混凝土连续梁悬臂法施工实践,针对合龙段施工中劲性骨架的结构设计、施工要点进行了必要的分析和阐述。     

ECONOMETRICS FOR GRUMBLERS: A NEW LOOK AT THE LITERATURE ON CROSS‐COUNTRY GROWTH EMPIRICS

Abstract Since the seminal contribution of N. Gregory Mankiw, David Romer and David N. Weil in 1992 the growth empirics literature has used increasingly sophisticated methods to select relevant growth determinants in estimating cross‐section growth regressions. The vast majority of empirical approaches, however, limit cross‐country heterogeneity in production technology to the specification of total factor productivity, the ‘measure of our ignorance’. In this survey, we present two general empirical frameworks for cross‐country growth and productivity analysis and demonstrate that they encompass the various approaches in the growth empirics literature of the past two decades. We then develop our central argument, that cross‐country heterogeneity in the impact of observables and unobservables on output as well as the time‐series properties of the data are important for reliable empirical analysis.     

尿素车间一段分解塔筒节局部减薄原因及防范对策

对某化肥公司尿素一段分解塔筒节进行了宏观检验、仪器测量和壁厚校核。根据实际检验情况对尿素一段分解塔筒节的腐蚀原因进行了分析。结合实际情况对尿素一段分解塔筒节的修理和使用提出了防腐措施。     

Customers’ migration paths decided by relative advantage: longitudinal and comparative case study of successive generations of logic semiconductor technology

ABSTRACT

Understanding customers and their behaviour has become important for success in a market. When successive generations of technology are available in a market, customers will decide their migration paths based on certain factors. This study focused on the relative advantage of successive generations positioned at different levels. Based on a longitudinal and comparative research design, the migration paths of customers are identified by understanding how their behaviours are affected by this relative advantage. The preferred relative advantage is positioned differently at early and majority markets. According to observations of the actual migration paths of 14 semiconductor customers, early and majority market players exhibit different migration paths (switching, new entrance, leapfrogging, or diffusion paths) depending on the relative advantage of the migrating generation. This study has theoretical implications by understanding the mechanism of customers’ migration based on the relative advantage, as well as practical implications for suppliers and customers to sustain their competitive advantage in a market.     

Stated Attribute Non‐attendance in Successive Choice Experiments

Attribute non‐attendance in choice experiments affects willingness‐to‐pay (WTP) estimates and therefore the validity of the method. A recent strand of literature uses attenuated estimates of marginal utilities of ignored attributes. Following this approach, we propose a generalisation of the mixed logit model, whereby the distribution of marginal utility coefficients of a stated non‐attender has a potentially lower mean and lower variance than those of a stated attender. Model comparison shows that our shrinkage approach fits the data better and produces more reliable WTP estimates. We further find that while reliability of stated attribute non‐attendance increases in successive choice experiments, it does not increase when respondents report having ignored the same attribute twice.