高铁网络接入、企业绩效提升与创新促进——基于准自然实验的上市公司样本分析

本文将高铁建设作为一次"准自然实验",研究2007—2016年高铁站点开通对上市公司企业绩效的影响。研究结果表明:(1)企业融入高铁网络后能够显著地提高企业绩效,且这种影响具有一定的持续性。此外,以城市历史上明代驿站数量作为工具变量进行内生性检验,结论也未有改变。(2)分样本机制验证结果说明,高铁开通对城市制造业和服务业企业的发展都具有促进作用,但对服务业的影响更强、更显著。(3)中介模型的回归结果说明,高铁开通对企业科研人员具有集聚作用,并能够进一步提升企业绩效。     

流通速度与经济增长--对索洛经济增长解释框架的扩展

本文通过对费雪方程式的一般化抽象,将经济增长与流通速度紧密联系在一起,得到了流通方程式.根据流通方程式,资本、劳动力和技术进步三要素对经济增长的贡献等于各自存量与流通速度的乘积.在此基础上,本文通过一系列数学变换,对索洛经济增长解释框架进行了扩展,得到了新的经济增长决定函数.该决定函数提示了流通速度与经济增长的关系,即,在要素增长率特别是技术进步存量增长率一定的情况下,经济增长率取决于社会流通速度的增长率.本文还依据马克思经济学原理和现代经济学理论,进一步分析了流通速度增长率的构成,认为制度环境状况、交通基础设施(装备)条件、社会交易总量和信息技术状况是流通速度增长率的最终决定因素.     

我国医药上市公司资本结构调整速度研究

我国医药上市公司资本结构调整速度非常缓慢,与其他行业、其他国家有着比较大的差异。产品独特性是其主要的影响因素,公司规模、净资产收益率、股权结构等指标对其影响也比较显著。我国医药上市公司资本结构调整动力与调整能力不相匹配,这主要与医药产业创新、银行利润导向、国有医药独大、国有企业治理、我国企业债市场不发达等因素有关。     

基于单片机的可调速音乐流水灯

目前,对于单片机流水灯的研究,大多利用51单片机,软硬件相结合,构造出最简单的流水灯。文章在此基础上扩展键盘控制流水灯花样、控制流水灯显示数字或图案等功能。另外针对单片机演奏音乐时音调和节拍的确定方法,产生更加纯正的音色。     

晶闸管直流电动机调速装置故障及对策研究

电机的调速系统在工农业生产、交通运输以及日常生活中的应用起着越来越重要的作用。文章主要针对晶闸管直流电动机调速装置故障及处理方法进行了分析。     

模糊自整定PID双闭环直流调速系统建模及仿真分析

本文章对于工程上常采用的直流调速控制系统,详尽地阐述了双闭环调速系统的PID控制原理,分别对调速系统的电流环、转速环的动态特性、抗干扰特性进行simulink仿真实验。针对在克服较大扰动和提高系统动态品质的要求,设计了一种基于模糊控制理论的PID控制器并对调速系统进行仿真实验。通过与原有PID控制器进行对比,发现基于模糊控制理论的PID控制器可以显著提升控制效果,并且具有非常强的抗干扰特性,快速的系统响应,良好的动态特性等。     

Consumption, New Protagonist in 2007 GDP

Not long ago, the National Bureau of Statistics released its 2007 Macro Economy Index. Social consumption retail sales reached RMB 8.9 billion, increased by 16.8 percent over the previous year, or 3.1 percentage points higher; the whole investment in social fixed assets was valued RMB 13.7 billion, a year-on-year increase of 24.8 percent, that is 0.9 percentage points higher; and trade surplus amounted to RMB 24.7 billion, rising by 47.7 percent compared with the same period last year, 26.3 percentage points falling over the increasing speed last year. According to preliminary estimates, GDP for the year was RMB 24.67 trillion, up by 11.4 percent from the previous year,     

Estimating the speeds of long-run technological catch-up and growth of total factor productivity for countries

This paper constructs a dynamic production frontier function under the framework of a forward-looking rational expectations model, taking the effect of quasi-fixed inputs into account. The sample comprises balanced panel data of 36 countries over the period from 1990 to 2009. Evidence is found that all of the four country groups show the technological catch-up phenomenon in the long run and experience total factor productivity (TFP) growth. Their TFP growth is primarily driven by long-run technical efficiency improvement, followed by technological progress. The Non-G7 and Non-NICs groups are the top two groups in terms of speeds of long-run technological catch-up and rates of TFP growth.     

Speed or quality? How the order of market entry influences the relationship between market orientation and new product performance

The role of market orientation as an antecedent of new product performance has been extensively documented in the literature. What is less clear, however, is how firms should make use of their market orientation under different market conditions. This study addresses this question by investigating how market orientation leads to superior new product performance for products that enter the market at different times. In particular, the study examines the moderating effect of order of market entry on the mediated relationship between market orientation and new product performance via product quality and innovation speed. Data from a sample of 244 new product development projects show that a firm's market orientation can improve the performance of first-to-market products and late entrants by facilitating the development of quality products, whereas it can improve the performance of early entrants by facilitating greater innovation speed.     

A rolling horizon approach to the high speed train rescheduling problem in case of a partial segment blockage

This paper reschedules train services on a double-track high speed railway in a disrupted situation, where one track of a segment is temporarily unavailable. We have to decide the sequence of train services passing through the blocked segment, the arrival and departure time of each train service at each station, and the canceled train services. Three practical train rescheduling strategies are explicitly compared and formulated by three MILP models. The uncertain duration of the disruption is handled. A rolling horizon approach is applied to solve our models. The models are tested on a real-world instance of the Beijing-Shanghai high speed railway.