Hydraulic erosion of concrete by a submerged jet

The hydraulic erosion of concrete is often found in civil and marine engineering construction. The present study explores the effects of several erosion parameters on the material loss of a concrete specimen subject to the hydraulic flow produced by a submerged jet. Such an investigation has rarely been reported in the literature. The concrete specimen has a typical compressive strength of 35 MPa, and the experimental parameters include the exposure time, incidence angle, standoff distance, and the hydraulic jet pressure. The impinging velocity is estimated based on the distance considered in the round jet model. The regression analysis shows the relationship between each parameter and the material loss. One finds that the material loss is proportional to the exposure time and the hydraulic pressure. The maximum erosion lies at an incidence angle of around 30° to 45° and is affected by the fourth-order polynomial of impinging velocity. The result of the present study provides a reference to engineering practice where concrete erosion is a concern.     

LiBH4／Mg复合氢化物的储氢性能研究

通过球磨LiBHdMg，使得镁的吸放氢性能得到明显改善。活化结果显示，在氩气气氛下，球磨1h的LiBHdMg混合物经250℃，60min处理后的吸氢量可以达到6．7％（质量分数，下同）。200℃，80min处理后的吸氢量可以达到3．0％。而纯镁粉在相同条件下几乎不吸氢。PCT结果显示，LiBH4也明显改善镁氢化后的放氢性能。     

盖下坝水电站坝址区岩溶发育情况初步分析

盖下坝水电站工程为高山峡谷型电站,坝址区及附近岩石为碳酸盐岩,属中等坚硬易溶岩.岩溶发育是影响本工程库水外渗的重大工程地质问题之一.从施工开挖揭示的各种溶蚀现象中分析岩溶发育特征及其规律,为防渗设计提供依据.     

多场景视频监控中的人物连续跟踪

针对多场景监控,提出一种能在非重叠的多摄像机之间,实时地检测与被跟踪行人（目标）的视频监控系统。该系统分别对每个摄像机视频进行背景建模、前景检测以及运动目标的特征提取,当目标离开摄像机视域的时候,根据已知的拓扑关系向相关摄像机发布监控任务,当有目标进入处于有效监控状态的摄像机视域时,进行目标匹配,从而实现在多摄像机系统中对行人目标的持续跟踪。实验表明,该系统在非重叠摄像机场景中能实现实时的、鲁棒的目标跟踪。     

一种面向中小企业PDM系统的设计与实现

根据中小企业在信息化建设中对于产品数据管理的实际需求,针对某一具体行业设计了一个适合中小企业的产品数据管理系统。分析系统的开发平台和采用基于．Net框架下采用B／S模式的系统结构,阐述系统具有的图档管理、产品结构和配置管理、项目管理和安全管理等主要功能。应用结果表明,该系统能有效地提高企业对产品数据管理的效率。     

Java程序设计课程的案例设计

解释了"项目驱动、案例教学、理论实践一体化"教学方法的基本思路,给出了Java程序设计课程的案例设计.     

Fast medical concept normalization for biomedical literature based on stack and index optimized self-attention

Neural Computing and Applications - Medical concept normalization aims to construct a semantic mapping between mentions and concepts and to uniformly represent mentions that belong to the same...