大型发电机组定子接地保护3U_0定值整定的探讨

通过对大型发电机组定子接地保护的作用和目前所使用的定子接地保护整定方法进行了介绍,分析计算了中性点经配电变压器接地的发电机接地电流大小与保护范围之间的关系,结合《导则》规定的动作整定原则,提出了发电机定子接地保护3U0定值与出口时限的选择方法,并通过实例计算主变高压侧单相接地故障产生的传递电压对定子接地保护的影响,最后给出了三段式定子接地保护的整定建议。     

基于视觉信息的PCNN参数自适应设定及模型改进

脉冲耦合神经网络(PCNN)参数决定该模型在数字图像处理领域的应用.现阶段网络参数自适应设定是依据图像统计信息或网络自身结构.基于此,提出基于生物视觉信息的PCNN参数自适应设置方法及模型改进.该方法通过对生物视觉感知理论与PCNN网络性质的分析,揭示了视觉感知理论与PCNN网络参数M、W和β的同源性,给出依据视觉感知模型自适应设定PCNN网络参数W、M和β的方法,并设计出具有生物视觉特征的PCNN改进模型.实验验证了该模型的几何不变性,在基于内容的图像检索领域取得了良好效果.     

Evaluation of Various Alternative Economical and High Throughput SARS-CoV-2 Testing Methods within Resource-Limited Settings

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak posed a challenge for diagnostic laboratories worldwide, with low-middle income countries (LMICs) being the most affected. The polymerase chain reaction (PCR) is the gold standard method for detecting SARS-CoV-2 infection. However, the challenge with this method is that it is expensive, which has resulted in under-testing for SARS-CoV-2 infection in many LMICs. Hence, this study aimed to compare and evaluate alternative methods for the mass testing of SARS-CoV-2 infection in laboratories with limited resources to identify cost-effective, faster, and accurate alternatives to the internationally approved kits. A total of 50 residual nasopharyngeal swab samples were used for evaluation and comparison between internationally approved kits (Thermo Fisher PureLink™ RNA Isolation Kit and Thermo Fisher TaqPath™ COVID-19 Assay Kit) and alternative methods (three RNA extraction and four commercial SARS-CoV-2 RT-PCR assay kits) in terms of the cost analysis, diagnostic accuracy, and turnaround time. In terms of performance, all of the alternative RNA extraction methods evaluated were comparable to the internationally approved kits but were more cost-effective (Lucigen QuickExtract™ RNA Extraction Kit, Bosphore EX-Tract Dry Swab RNA Solution and Sonicator method) and four commercial SARS-CoV-2 RT-PCR assay kits (Nucleic Acid COVID-19 Test Kit (SARS-CoV-2), abTES^TM COVID-19 qPCR I Kit, PCL COVID19 Speedy RT-PCR Kit, and PCLMD nCoV One-Step RT-PCR Kit) with a sensitivity range of 76–100% and specificity of 96–100%. The cost per sample was reduced by more than 50% when compared to internationally approved kits. When compared to the Thermo Fisher PureLink™ Kit and Thermo Fisher TaqPath™ COVID-19 Assay Kit, the alternative methods had a faster turnaround time, indicating that laboratories with limited resources may be able to process more samples in a day. The above-mentioned cost-effective, fast, and accurate evaluated alternative methods can be used in routine diagnostic laboratories with limited resources for mass testing for SARS-CoV-2 because these were comparable to the internationally approved kits, Thermo Fisher PureLink™ Kit and Thermo Fisher TaqPath™ COVID-19 Assay Kit. The implementation of alternative methods will be the most cost-effective option for testing SARS-CoV-2 infection in LMICs.     

日本南海海槽东部天然气水合物产出与富集特征

根据日本南海海槽东部天然气水合物钻探与综合大洋钻探计划研究成果,分析总结了该区天然气水合物形成的地质背景与赋存特征。南海海槽区作为构造活动强烈的会聚式大陆边缘,大型增生楔与断裂系统十分发育,富含重力流沉积物。特别是该海槽北部向陆斜坡水深2 000 m以浅海域,发育一系列弧前盆地,盆地内第四系未固结沉积物广泛分布,沉积速率较高,为水合物的形成提供了良好的环境。水合物钻探取心分析揭示,南海海槽东部天然气水合物为Ⅰ型结构,水合物分解气中甲烷组分占比普遍高达99.9%以上,甲烷碳同位素分析显示为典型的生物成因气。水合物主要以孔隙填充型产出,优先选择在富砂层中富集,富砂层段水合物饱和度一般为50%~60%,可高达80%~90%,泥质层中水合物饱和度极低。     

串行通信中定时大批量数据传输的编程技术

本文详细了在工业现场强电磁干扰的环境下，基于WINDOWSTM98操作系统的工控机与MCS－51单片机间串行口传输大批量数据的编程技术。文中着重分析了实际通信中可能出现的传输错误以及通信线路Timeouts设定等问题，同时给出了相应的解决方案。