填筑土体压实度快速检测试验

针对平原水库围坝填筑压实度快速检测做了大量的"三点击实"和标准击实试验。分析了三点击实试验过程中减水情况及加、减水情况下试验方法的可行性及其数据合理性,和标准击实试验方法进行了比较,认为减水情况及加、减水情况下试验方法是可行的,在减水情况下最优含水率和填土含水率的差值一般在-3%～0,同时试验过程中土体减水率小于6%时,三点击实试验成果比较合理。用三点击实试验方法填筑土体压实度所用时间比标准击实试验的方法省6～8h,三点击实试验填筑土体压实度的方法针对土体特性差别较大的工程中适用性强。提出了减水情况下的三点击实试验步骤及试验过程中的注意事项。     

小功率数码中频稀土永磁发电机组的设计与试验

中频稀土永磁发电机具有功率密度大、体积小、结构简单的特点,以MC68HC908MR32单片机控制为核心的小功率数码中频稀土永磁发电机组,采用"交—直—交"变换,将永磁发电机发出的中频电压变换成单相工频电源电压,样机实测结果表明该机组具有工频电压波形畸变率和电压调整率小、效率高等特点.     

三相异步电动机断相保护器

详述了断相保护器的电路结构与工作原理。当电容C2上的电压上升到BT33C的峰点电压时,小灵敏继电器KA通电,切断电动机的电源,从而避免了三相异步电动机单相运行致使电流过大而被烧毁。为了使小灵敏继电器KA通电充分,能确保其常闭触点断开,及时切断电动机的电源,应使BT33C的电流不会很快降到谷点电流以下,电容C2上的电压能较长时间的大于BT33C的谷点电压。由于电容C2上的电压不能跃变,这样可避免电网三相电压瞬间不平衡造成断相器误动作。     

磁放大器式硅弧焊整流器控制特性分析

本文详细分析了三相内反馈磁放大器式硅弧焊整流器的控制特性,给出了各铁心的磁通密度变化规律及输出电压 U_o 与控制电流 I_K 之间的数学表达式。对确定内反馈磁放大器式硅弧焊整流器一些参数有一定的指导意义。     

A logistic regression point of view toward loss given default distribution estimation

We propose a new procedure to estimate the loss given default (LGD) distribution. Owing to the complicated shape of the LGD distribution, using a smooth density function as a driver to estimate it may result in a decline in model fit. To overcome this problem, we first apply the logistic regression to estimate the LGD cumulative distribution function. Then, we convert the result into the LGD distribution estimate. To implement the newly proposed estimation procedure, we collect a sample of 5269 defaulted debts from Moody’s Default and Recovery Database. A performance study is performed using 2000 pairs of in-sample and out-of-sample data-sets with different sizes that are randomly selected from the entire sample. Our results show that the newly proposed procedure has better and more robust performance than its alternatives, in the sense of yielding more accurate in-sample and out-of-sample LGD distribution estimates. Thus, it is useful for studying the LGD distribution.     

高校研究生导师学术休假制度刍议

文章对建立导师学术休假的必要性以及我国导师学术休假的现状作了分析,重点介绍了构建导师学术休假制度的实施策略,总结了为建立具有中国大学特色的学术休假制度而需逐步营造的导师学术休假的政策环境。     

目前高校学生档案管理的困境及对策剖析

高等院校学生档案是学生在校期间各方面表现及社会实践活动的真实记录,是国家选拔任用人才的重要依据,然而目前我国高校学生档案管理存在学生档案材料不全面、档案管理制度不完善、现代化软件管理系统不健全等诸多问题。本文对这些问题进行了分析,并提出了加强高校学生档案的相应对策。     

外贸企业会计内控研究

对外贸企业而言,会计内部控制机制是外贸企业财务处理、业务程序等进行规范的一种管理手段,是外贸企业内部管理的基础和内部控制的关键控制点,在整个外贸企业的发展运行中发挥着重要作用。基于此,通过探讨当前外贸企业会计内部控制机制的现状,对其未来发展提出了相关建议。     

Is the protection of beach and dune vegetation compatible with tourism?

The paradox of development vs. protection and conservation of the coasts highlights the need to determine if tourism and conservation can be compatible rather than opposite activities. We analyzed the spatial and temporal changes in vegetation cover, composition and diversity in three beaches located in the state of Veracruz (Mexico) with different levels of tourism activity (Natural, Trailer Park and Hotels). We calculated tourist density and evaluated vegetation cover, species richness and diversity and analyzed the changes before and after three holiday seasons (winter, spring and summer). The Natural site had the highest vegetation cover (42.8 m²), species richness (14) and diversity (1.50), and Trailer Park the lowest (4.9 m², 8 species, and 0.897 respectively). The BACI (Before-After-Control-Design) analysis showed no significant differences before and after the holiday seasons. Our results show how low and medium density tourism can be compatible with the protection of beach and coastal dune vegetation.     

Are Current Account Deficits in the OECD Countries Sustainable? Robust Evidence from Time-Series Estimators

This study examines the sustainability of current account deficits (CADs) and validity of intertemporal budget constraint (IBC) for 24 OECD countries. While the OLSEG, ML system, and OLSGH estimates of the model do not provide support, the GMM, DOLS, and NLLS estimates provide consistent support for the sustainability of CADs across most countries. The estimates of the model with multiple structural breaks reinforce the sustainability of CADs. The results provide dominant support for the sustainability of CADs and validity of IBC across most countries. The CADs are only short-run phenomena and are balanced by future surpluses.