凿井水下底卸式自动卸料吊桶

吊桶是立井井筒开凿时期提升矸石和运送材料及升降人员的主要容器,吊桶的卸矸目前多采用挂钩式或座钩式卸料方式;但是随着矿井的开凿深度不断延伸,在过透水层时,由于探放水不及时或涌出水比较大,超出了井筒的排水量,或者是由于冷冻井在解冻后,井筒的井筒质量不过关,各别井壁也会发生透水事故;这就会出现淹井事故,有时淹井深度达二三百米。对于处理这种淹井事故,往往只有一个办法,那就是用沙或混凝土对井筒回填;这就需要吊桶在下到几百米下的水底自动把料卸掉,但现在矿井常用的挂钩式吊桶和座钩式吊桶已经不能满足这个需要了。     

Measuring the liquidity part of volume

Based on the concept that the presence of liquidity frictions can increase the daily traded volume, we develop an extended version of the mixture of distribution hypothesis model (MDH) along the lines of Tauchen and Pitts (1983) to measure the liquidity portion of volume. Our approach relies on a structural definition of liquidity frictions arising from the theoretical framework of Grossman and Miller (1988), which explains how liquidity shocks affect the way in which information is incorporated into daily trading characteristics. In addition, we propose an econometric setup exploiting the volatility–volume relationship to filter the liquidity portion of volume and infer the presence of liquidity frictions using daily data. Finally, based on FTSE 100 stocks, we show that the extended MDH model proposed here outperforms that of Andersen (1996) and that the liquidity frictions are priced in the cross-section of stock returns.     

Trading volume and stock returns: A meta-analysis

I examine 468 estimates on the relationship between trading volume and stock returns reported in 44 studies. I study publication bias together with Bayesian and frequentist model averaging to explain the heterogeneity in the estimates. The results yield three key conclusions. First, publication bias distorts the findings of the primary studies. Second, the predictability of stock returns varies with different markets and stock types. Third, different data characteristics, structural variations and methodologies used drive the heterogeneity in the results of the primary articles. In particular, one should be cautious when using monthly data or VAR models.     

Corporate Governance and Corporate Bond Liquidity

Using a unique dataset of corporate bond trading information and corporate governance evaluation scores, this study examines the determinants of corporate bond market liquidity in Korea. In particular, this study explores whether corporate governance performance of a company influences liquidity of bonds issued by the company. The paper reports three important findings. First, the issue size and age of bond are important determinants of bond liquidity. Second, liquidity of corporate bonds is influenced by changes in macroeconomic conditions. Third, and most importantly, better corporate governance increases liquidity of corporate bonds. This result suggests that corporate governance is an important determinant of bond liquidity, as it lowers transaction costs by improving transparency and reducing asymmetry of information. This paper contributes to the literature by providing new evidence that corporate governance performance is an important determinant of liquidity in corporate bond markets.     

一种便携式气体体积计量系统的设计

为了在实验室中计量厌氧发酵时产生的沼气体积,设计了一种便携式气体体积计量系统,并分析了系统的构成及运行流程,给出了主要硬件及软件设计方法。试验结果表明,该系统结构合理,使用方便,满足实验室测量气体体积的需要。     

Venture capital trusts and the expiration of IPO lock-up provisions

Venture capital trusts (VCTs) were introduced to provide private equity capital for small expanding companies and to promote innovation. Investors in initial public offerings are rewarded with tax relief on the cost of lock-up provisions to stabilize the market. This paper examines the market reaction and trading activity around the expiration of lock-up provisions of 148 VCTs listed on the London Stock Exchange from 1995 to 2006. Downward-sloping demand curve theory suggests that an increased supply of VCT shares at the expiry date could shift their value to a new equilibrium at a lower price. Supporting this prediction, we document evidence of negative abnormal returns as well as permanent increases in the price discount relative to net asset value and trading volumes at and around the expiries of the required holding periods of VCTs. In addition, less negative abnormal returns, lower abnormal discounts and lower abnormal trading volumes are associated with VCTs that invest in AIM-listed companies due to lower information asymmetry, that experience lower prior performance due to a less pronounced disposition effect, and that are subject to a shorter lock-up horizon or are offering more generous tax benefits.     

The Role of Financial Ratios in the Variance of Stock Trading Volume in Emerging Stock Markets

The study used quarterly panel data of 6 years from 2010 to 2015 of all companies listed on both Vietnamese stock markets including the Ho Chi Minh City Stock Exchange and Ha Noi Stock Exchange, and on three leading industries consisting of insurance-banking, foodstuff, and real estate to explore the relationship among four key financial ratios and stock trading volume. Two models, fixed effects model (FEM) and random effects model (REM), with robust standard errors, were applied for this study. The key findings showed that earnings before tax on sales, debt on owner’s equity, and owner’s equity on total assets significantly influenced trading volume.     

基于重心法与物流量预测的物流园区选址

在研究物流园区选址理论的基础上,为使物流运输成本最小和物流园区的建设符合长远发展,在对物流园区选址时使用理论中的重心法并建立相应选址数学模型,将数学模型与趋势外推预测法预测的物流园区物流量结合,在定量的基础上计算得到物流园区的选址位置,同时为精确地得到选址位置开发了基于重心法的选址模型软件。最后通过吉木乃县物流园区选址说明该方法的可行性。     

物流需求量灰色马尔科夫模型预测

针对物流信息的不确定性与复杂性,用灰色马尔科夫模型对黑龙江省物流需求的指标量"货运量"与"货物周转量"进行了预测。预测结果为黑龙江省物流产业的发展政策及物流基础设施的规划和设计提供了决策依据,对提高黑龙江省物流产业的发展水平具有一定的参考意义。     

桥梁灌注桩后压浆施工技术

本文结合工程实例,介绍了桥梁后压浆施工工艺在铁路客运专线中的应用,通过对已施工的桩基进行桩底和桩侧压注水泥浆的方法,从而提高总桩侧阻力和总桩端阻力,有效控制了工后沉降,实现了提高桩基承载力的目标。