生产建设项目不同水土保持监测方法的比较分析

生产建设项目的水土保持监测内容由1个目标层、6个控制层、29个要素和96个指标构成。介绍了长江流域水土保持监测中心站开展水土保持工作主要采取的方法,即资料分析法、实地量测监测、定点地面监测、遥感监测、三维激光扫描测量、摄影测量和远程实时监控技术等。比较了各监测方法的原理、适应性及特点。由于各种监测方法均不是独立运用于某一个项目工程,因此,根据项目工程总体布局和工程施工可能造成的水土流失部位的特点,应相互结合各自特点,选择适合的监测方法,对生产建设项目水土流失及水土保持措施进行全过程监测。     

黑方台焦家4号黄土滑坡发育特征及滑动机理

20世纪60年代以来,大量的灌溉系统在黄土地区建设运营,解决了农业的干旱问题,但同时灌溉也诱发了大量的滑坡。其中,2015年1月28日20:00,甘肃省永靖县焦家村发生了一起中等规模的黄土滑坡,滑坡严重影响其下方309国道线和六盘峡水库的安全。采用对裂缝分布、水文地质的调查,结合低空摄影测量、精细工程地质测绘、室内三轴试验等研究方法,对焦家4号滑坡的基本特征进行了分析,对形成滑坡的成灾机理有了初步认识。结果表明:(1)滑坡发生前,后缘裂缝有明显的变形情况;(2)滑坡滑动距离为548.3 m,体积为15.35万m~3,面积为6.6万m~2;(3)饱和黄土应力应变模式表现为强烈的应变软化剪缩型,并具有一定的静态液化特性;(4)滑坡是饱和黄土层静态液化引起的。     

陶瓷坯体增强剂聚丙烯酸钠在艺术瓷成形过程的应用

本文合成了一系列不同相对分子质量的聚丙烯酸钠,应用于艺术瓷的坯体中,研究了聚丙烯酸钠对艺术瓷坯体强度、变形率的影响,并对聚丙烯酸钠增强机理进行了探讨。结果表明:聚丙烯酸钠可有效地提高艺术瓷坯体的成形强度,减少了坯体的变形率,当增强剂c加入的质量分数为0.6%时,坯体的干燥强度增加率达167.5%,坯体的变形率从50%降低到10%。     

本构模型对面板堆石坝应力变形的影响

邓肯-张E-B模型,能考虑土体的非线性特征以及应力历史对变形的影响,比较符合土体的受力特征。理想弹塑性D-P模型是在摩尔-库伦模型的基础上考虑了静力压力的影响,广泛应用于岩体材料的模拟。堆石体是介于土体与岩体之间的一种土石混合体,其本构模型的选择一直存在较大的争议。基于APDL二次开发,将E-B本构模型成功引入到ANSYS静力分析中,与理想弹塑性D-P模型的计算成果进行对比分析,并对E-B模型的主要参数进行敏感性分析。研究成果表明:本构模型对堆石体竖向位移影响较大,但对堆石体的应力、面板应力、及面板位移影响较小;E-B模型参数中K,n以及荷载子步对面板堆石坝应力、位移的影响较大。     

A survey of traffic-based routing metrics in family of expected transmission count for self-organizing networks

Self-Organizing Networks (SONs) are attractive for applications where flexibility, resilience, and a large network service area are required. In order to meet the requirements of those applications, the principal issue is to guarantee efficient routing in SONs. Hence, the design and selection of appropriate routing metrics is important. A mass of metrics have been proposed in the past several decades. Among all the metrics, Expected Transmission Count (ETX) has drawn the most attention. Since the proposal of ETX, many ETX-based or extended metrics have been proposed. ETX and its descendants compose the ETX family. This paper is an attempt to analyze, compare and summarize traffic-based routing metrics in the ETX family. Details of each routing metric are presented and analyzed. Some of our viewpoints on the principal for designing metrics in SONs are presented.     

基于GIS电子地图制定输电巡视计划的研究

输电巡视计划是输电线路开展日常巡维工作必不可少的部分。如何实现快速、便捷地制定巡视计划,提升巡视计划开展的实效性,已成为输电线路运维管理工作的迫切要求。文章从输电线路周边环境的特点出发,在对其真实环境的复杂程度进行分析的基础上,结合当前主流的地理信息技术,提出了基于GIS电子地图制定输电巡视计划的设计方案,并详细阐述了该方案的实现模式和实际应用成效。     

计算机网络安全威胁的技术特征与防范措施

目前,在计算机网络中存在许多不安全因素,这些因素不仅会对计算机的正常运行造成影响,还会对社会发展造成较大的影响.因此,我们要结合具体情况,采取有针对性的防范措施.简要分析了计算机网络安全威胁的特征和防范措施,希望可以为相关单位提供一些有价值的参考意见.     

浅析加快300 MW机组启动速度的方法及措施

随着电网的装机容量日益增大,机组的启动次数也在逐日增多。从保证机组安全经济运行的角度出发,结合笔者直接或间接参与制定的技术措施,简要分析了影响机组启动速度的因素和改善措施,以期为其他发电厂在机组启动方面提供一些参考和建议。     

Automating fluid delivery in a capillary microfluidic device using low-voltage electrowetting valves

A multilayer capillary polymeric microfluidic device integrated with three normally closed electrowetting valves for timed fluidic delivery was developed. The microfluidic channel consisted two flexible layers of poly (ethylene terephthalate) bonded by a pressure-sensitive adhesive spacer tape. Channels were patterned in the spacer tape using laser ablation. Each valve contained two inkjet-printed silver electrodes in series. Capillary flow within the microchannel was stopped at the second electrode which was modified with a hydrophobic monolayer (valve closed). When a potential was applied across the electrodes, the hydrophobic monolayer became hydrophilic and allowed flow to continue (valve opened). The relationship between the actuation voltage, the actuation time, and the distance between two electrodes was performed using a microfluidic chip containing a single microchannel design. The results showed that a low voltage (4.5 V) was able to open the valve within 1 s when the distance between two electrodes was 1 mm. Increased voltages were needed to open the valves when the distance between two electrodes was increased. Additionally, the actuation time required to open the valve increased when voltage was decreased. A multichannel device was fabricated to demonstrate timed fluid delivery between three solutions. Our electrowetting valve system was fabricated using low-cost materials and techniques, can be actuated by a battery, and can be integrated into portable microfluidic devices suitable for point-of-care analysis in resource-limited settings.