小浪底与西霞院水电站水轮机调速器的异同及特点分析

水轮机调速器是水电站重要的自动化设备,其质量的好坏直接影响到电能品质和水电站安全及经济运行.文章主要从小浪底和西霞院及西沟水电站调速器的选用来分析其各自调速器的异同及特点.     

中缅伊江上游电源电站孤网运行探讨

近年中缅两国合作开发伊洛瓦底江上游水电,成为举世瞩目的能源合作工程。但由于当地电能匮乏,无法为大电站施工提供电能,须先期建设1座施工电源电站。由此,组成一个孤网供电系统,鉴于缅甸的环境特点,这种孤网运行缺点和困难也是少见的,笔者就这种电网运行作分析探讨。     

海洋酸化研究进展

介绍了海洋酸化的原因及目前研究的一些进展。随着人类向大气中大量排放二氧化碳,引发了温室效应和海洋酸化等环境问题,海洋酸化将会导致海水碱度升高从而溶解更多的二氧化碳,还会导致海洋生物链发生变化,加快海洋生物数量的退化速度,并且海洋酸化会加剧一些全球气候问题。     

FPGA动态局部重配置在软件无线电中的应用

论文简单概述了Xilinx现场可编程门阵列(FPGA)动态局部重配置的技术特点以及在现代软件无线电(SDR)中的应用.并以一个工程示例着重介绍了在某波形处理模块上采用飞思卡尔处理与FPGA内部微处理器配合的方案对FPGA进行局部功能动态配置的工程实现.     

Forward kinematic singularity avoiding design of a Schönflies motion generator by asymmetric attachment of subchains

In most of the previous studies on parallel mechanisms (PMs), architectural design mainly relying on symmetric geometry was investigated without in-depth analysis of its performance. This work demonstrates that such a symmetric geometry of multiple subchains sometimes induces a forward kinematic singularity which degrades the overall kinematic performance of PMs within the desired workspace and claims that an asymmetric attachment of those subchains on a moving platform can effectively resolve such a singularity problem. A 4-Degree-of-Freedom (DOF) PM exhibiting Schönflies motions is examined as an example device. First, its mobility analysis and kinematic modeling via screw theory are conducted. Then a singularity analysis based on Grassmann line geometric conditions is carried out, and the forward kinematic singularities of the mechanism are identified and verified by simulations. Based on these analysis and simulations, a forward kinematic singularity-free design is suggested. To show the high potential of the device in practical applications, its output stiffness and dynamic motion capability are examined. Then a prototype is built and its motions capability is verified through experiments.     

Quantitative characterization of the focusing process and dynamic behavior of differently sized microparticles in a spiral microchannel

In this paper, a spiral microchannel was fabricated to systematically investigate particle dynamics. The focusing process or migration behavior of different-sized particles in the outlet region was presented. Specifically, for focused microparticles, quantitative characterization and analysis of how particles migrate towards the equilibrium positions with the increase in flow rate (De = 0.31–3.36) were performed. For unfocused microparticles, the particle migration behavior and the particle-free region’s formation process were characterized over a wide range of flow rates (De = 0.31–4.58), and the emergence of double particle-free regions was observed at De ≥ 3.36. These results provide insights into the design and operation of high-throughput particle/cell filtration and separation. Furthermore, using the location markers pre-fabricated along with the microchannel structures, the focusing or migration dynamics of different-sized particles along the spiral microchannel was systematically explored. The particle migration length effects on focusing degree and particle-free region width were analyzed. These analyses may be valuable for the optimization of microchannel structures. In addition, this device was successfully used to efficiently filter rare particles from a large-volume sample and separate particles of two different sizes according to their focusing states.     

逊毕拉河流域径流季节变化特征及变异分析

以逊毕拉河流域吴家堡站2004～2009年实测水文资料为基础,并结合变异分析方法,分析了吴家堡地区降水和流量的季节变化特征。结果表明:降水和流量都具有明显的季节差异,且春季的变异系数大。     

降低煮练工序印染废水COD的常用方法

印染的煮练工序中要排放出大量的废水,这些废水如果不加以妥善处理就排入水体中,将会破坏当地的生态环境,给人们的身体健康带来危害。因此,寻求高效廉价的处理方法处理煮练废水有很重要的现实意义。     

江山市峡口水库发电输水隧洞进水口闸门竖井开挖爆破安全控制及评价

峡口水库发电输水隧洞进水口位置靠近坝体、厂房等建筑物,且周边岩体较为破碎.通过现场爆破振动试验制定了合理的爆破方案,并在爆破过程中实行爆破振动监测,按照监测结果及时调整爆破施工方案,达到对邻近建筑物进行保护的目的.     

宽垄沟灌垄上覆膜条件下土壤水分运移试验研究

为研究宽垄沟灌时灌水前后且有覆膜条件下水分在垄沟间的运移及再分布,采用对比试验方法,在大棚内模拟宽垄沟灌垄上栽培条件和灌水方案,采用中子仪进行水分观测。试验数据显示,采用垄上覆膜,灌水后垄沟水分的侧向入渗,表现出明显的侧向运移变化。垄背剖面两观测点表层,在灌水后144 h（6 d）,覆膜条件下分别达到田间持水量的80%...