蒲阳河倒虹吸斜坡段混凝土布料机设计与应用

混凝土布料机在南水北调工程施工中，解决了倒虹吸水平管身段混凝土输送问题，但在斜坡段施工中受到了制约。一是布料机斜坡运行的摩擦阻力、坡道阻力、风阻力等都影响布料机的运行安全，二是如何保证斜坡布料机的输送皮带一直处于水平状态。在原有水平混凝土布料机的基础上，通过计算将水平状态下的布料机增加一段可更换的支腿，并采用电机减速器驱动辅助卷扬机牵引相结合的方法，解决了蒲阳河倒虹吸斜坡段混凝土输送和布料机运行的问题。     

Using high, low, open, and closing prices to estimate the effects of cash settlement on futures prices

Due to dwindling commercial interest in the feeder cattle futures contract, the Chicago Mercantile Exchange (CME) decided to replace the contract's physical delivery provision with a cash settlement provision, arguing that cash settlement would help reduce price volatility and attracts more commercial interests. In this article, we apply stochastic volatility models to investigate the CME conjecture, using four different estimators based on opening, high, low, and closing prices, respectively. With each estimator, we find that the volatility of the feeder cattle futures price decreases after the implementation of cash settlement. We conclude that the change in the contract specification enhances price discovery and the contract's hedging performance.     

长江内支线口岸开展贸易便利化测评的实践和思考

根据长江内支线口岸实际,参考世界海关组织货物放行时间测算指南和世界银行跨境贸易营商环境评价方法,连续两年对长江某内支线口岸开展贸易便利化测评实证研究,并与世界银行的评价结果进行对比分析,提出在长江内支线口岸开展贸易便利化测评的对策建议。     

单张纸胶印机给纸机分离头压脚动力分析

压脚机构作为单张纸胶印机给纸机分离头的重要部件,其结构性能直接关系到印刷机给纸机纸张分离的速度和工作性能。为了提高给纸机分离头的工作稳定性,以某高速给纸机分离头为例,在分析给纸机分离头运动的基础上,利用动态静力分析方法对压脚的受力状况进行分析,为给纸机分离头其他机构的设计提供基础。     

Railway trip speeds and areal coverage. The emperor’s new clothes of effectivity?

Europe’s railways have experienced a general decline in the second half of the 20th century and a renaissance since the 1980s. Total network length has decreased fundamentally while high-speed rail (HSR) line construction has soared since then. Accordingly HSR has stipulated a lot of research, but only recently HSR’s impacts on settlement structure and transport regimes have been studied in depth. We embrace a passenger’s point of view and utilize a generalized overview model for illustrating the trade-offs between trip speeds of complete trip chains, access/egress legs and mainline trip lengths. In order to estimate input parameters, an overview of railway network and settlement structure of Austria is empirically derived. In four scenarios, we vary these input parameters to study the impact of timetable integration, speed upgrades on mainlines and access/egress modes on trip speed in the Austrian case. Our results show that travel speed advantages of mainline speed increases are quickly countervailed by access/egress improvements or timetable integration improvements. We conclude that finding harmonized optimum speeds, introducing clock-face timetable design and improving access/egress modes are promising strategies in comparison to unscrutinized further maximization of mainline travel speed levels at the expense of feeder/distributor lines quality.