基于Grails框架的Web应用开发

在分析当前Web应用开发的现状之后,介绍了新兴框架Grails,并对其MVC各层进行了简单的分析.通过Grails集成spring的acegi来开发一个简单的权限管理系统,并对中文化问题的解决方案进行了总结,对运用grails进行快速开发进行了全面的展示.总结了Grails框架在利用java资源进行企业级开发的优势.     

旅游安全事故周界安防入侵监测系统光纤Φ-OTDR传感器性能研究

为了全面评估旅游安全事故周界安防入侵监测系统的光纤Φ-OTDR传感器性能,本文采用了蝶形单模光纤和侵入板制作了光纤Φ-OTDR传感器,并将该传感器埋在细沙中,利用光纤Φ-OTDR(相位时域反射仪)搭建了基于分布式光纤Φ-OTDR传感器的旅游安全事故周界安防入侵监测系统,并对入侵信息(侵入者位置、重量及高度信息)进行了监测和评估。研究发现,采用所设计的光纤侵入板作为传感器,入侵监测系统能对侵入位置进行准确监测,定位精度小于10 m;重量监测下限达到15 kg;对越高的侵入者监测准确度越高,其准确度可达到99.6%。结果表明:基于光纤Φ-OTDR传感器的入侵监测系统能对长距离、大范围的入侵者进行准确监测,该入侵监测系统可广泛用于旅游景点危险禁区安全事故的安防实时监控。     

水电汇集多直流弱送端电网稳定控制及系统保护方案

渝鄂柔性直流背靠背和藏中-昌都联网工程投运后,具备水电汇集多直流弱送端特征的西南电网规模显著减小且长链式弱互联结构突出,电网安全稳定特性面临深刻变化。在深入分析西南电网运行特性和面临风险的基础上,指出了现有安全稳定控制策略的不足,提出了适应西南电网差异化稳定控制需求的系统保护架构和功能配置方案,并阐述了其关键技术。该系统中全网功角稳定控制、频率控制、电压控制、低频振荡和超低频振荡抑制,以及全景状态感知与监测等功能,可提高西南电网水电送出能力,支撑西南乃至国家电网安全稳定运行。     

The potential of III‐V semiconductors as terrestrial photovoltaic devices

III‐V semiconductors, GaAs and in particular InGaP, are used in many different electronic applications, such as high power and high frequency devices, laser diodes and high brightness LED. Their direct bandgap and high reliability make them ideal candidates for the realisation of high efficiency solar cells: in the past years they have been successfully used as power sources for satellites in space, where they are able to produce electricity from sunlight with an overall efficiency of around 30%. Nowadays, the use of arsenides and phosphides as photovoltaic (PV) devices is confined only to space applications since their price is much higher than conventional Si flat panel modules, the leading PV market technology. But with the introduction of multijunction solar cells capable of operating in high concentration solar light, the area and, therefore, the cost of these cells can be reduced and will eventually find an application and market also on Earth. This article will review the situation of semiconductor solar cell materials, focusing on Si, GaAs, InGaP and multijunction solar cells and will discuss future trends and possibilities of bringing III‐V technology from space to Earth. Copyright © 2006 John Wiley & Sons, Ltd.     

高比例水电多直流送端电网频率稳定协调控制技术及实践

针对异步联网运行后,高水电占比多直流外送西南电网面临的超低频振荡和频率失稳风险,构建了高比例水电多直流送端电网频率稳定控制框架。在传统控制措施基础上引入直流频率控制和紧急调整功能,提高送端电网频率稳定防御能力。基于直流频率控制器对送端电网频率响应特性的影响分析,提出了直流频率控制器与一次调频的配合关系以及考虑直流功率偏差的二次调频方法。提出了兼顾频率稳定和故障后潮流控制的多直流协调紧急功率调制方案。并通过实际故障后交直流协调控制系统实际动作情况,论述了频率稳定协调控制技术的有效性。     

基于少子样的核主泵电机滑动轴承可靠性研究

为研究一种核主泵电机滑动轴承的可靠性，在少子样无法进行大量整机试验的情况下，分析了核主泵电机滑动轴承的工况，确定了其失效模式并绘制了故障树。采用ANSYS软件仿真分析了轴承重要单元受力情况，求解了单元应力分布，根据应力-强度干涉法，利用蒙特卡罗抽样法得到了单元可靠度；采用数据手册法得到了其他单元的可靠度，并计算得到了轴承的整体可靠度。对少数试制轴承的缩小推力瓦模型样本和原尺寸冷却器展开试验，结果表明该核主泵电机滑动轴承满足工程可靠性要求。     

四川电网黑启动恢复控制研究及试验(二)——频率、并网控制及二次设备配置

在四川某电网黑启动现场试验的基础上,对黑启动期间孤网系统的频率、并网控制及相应二次设备的调整进行了分析.在考虑发电机组一次调频及负荷频率调节效应的基础上,根据系统的运行方程推导出负荷恢复后的频率降落公式;同时,结合实际中二次设备的配置原则及保护动作原理对黑启动期间二次装置的适应性和电网的抗干扰性分别进行讨论,并从使其最有利于系统恢复的方面提出了相应的调整及配置原则.     

Hierarchical Semiconductor Oxide Photocatalyst: A Case of the SnO2 Microflower

Nano-Micro Letters - Hierarchically assembled SnO2 microflowers were synthesized by a facile hydrothermal process. Field emission scanning electron microscope results showed these hierarchical...     

The effect of substrate type on SiC nanowire orientation

beta-SiC nanowires were synthesized on different monocrystalline substrates: Si (001), Si (111), 3C-SiC (001), 4H-SiC (0001), 6H-SiC (0001). The SiC nanowire growth was carried out using a Chemical Vapor Deposition method, with silane and propane diluted in hydrogen (3%) as precursors. The deposition was performed at atmospheric pressure and at 1100 degrees C, after dewetting of the Ni catalyst, which had been previously evaporated onto the substrate, to induce 1D growth according to a VLS process. The crystal structure of the nanowires, as determined by X-ray diffraction and High Resolution Transmission Electron Microscopy, corresponds to 3C-SiC polytype growing along a (111) direction, irrespective of the substrate. The occurrence of (111) stacking faults was observed, partly reduced for samples grown on 3C-SiC substrate. The growth on (111) substrate allowed to achieve a good vertical alignment of the nanowires, as investigated by Scanning Electron Microscopy. High Angle Annular Dark Field imaging and Energy Dispersive X-Ray spectroscopy were performed to study the catalyst particle on top of the wires and showed the formation of a nickel-silicon alloy.     

Detection of cow milk in donkey milk by chemometric procedures on triacylglycerol stereospecific analysis results

Stereospecific analysis is an important tool for the characterization of lipid fraction of food matrices, and also of milk samples. The results of a chemical-enzymatic-chromatographic analytical method were elaborated by chemometric procedures such as linear discriminant analysis (LDA) and artificial neural network (ANN). According to the total composition and intrapositional fatty acid distribution in the triacylglycerol (TAG) backbone, the obtained results were able to characterize pure milk samples and milk mixtures with 1, 3, 5% cow milk added to donkey milk. The resulting score was very satisfactory. Totally correct classified samples were obtained when the TAG stereospecific results of all the considered milk mixtures (donkey-cow) were elaborated by LDA and ANN chemometric procedures.