基于BP神经网络的交流输电线路可听噪声预测模型

可听噪声属于输电线路电磁环境的影响因子之一,其常规预测模型均存在使用条件受约束或预测误差偏大的问题.根据间接预测法的思想,以可听噪声通用表达式中的4个因素为输入变量,可听噪声值为输出变量,建立了三层结构的BP神经网络交流输电线路可听噪声预测模型.以国外多条输电线路可听噪声数据为样本,通过BP神经网络对样本进行训练,运用得到的模型对预测集线路的可听噪声值进行了预测.结果表明,与常规GE公式相比,采用BP神经网络预测模型的预测平均绝对误差要小1.641 4 d B(A).     

基于原子能量熵和CSM的配电线路故障分类方法

针对配电线路上的故障分类问题,提出了一种结合原子能量熵和连续字符串匹配(CSM)的故障分类方法.通过分析故障信号的暂态特征,利用原子分解法得到故障暂态信号的主导原子以及对故障信息进行补充的次级原子,计算原子能量熵作为故障特征量,较完备地描述了故障特征.应用CSM进行故障分类节省了智能算法故障辨识中参数选择和优化的时间,通过建立的编码规则,将故障特征进行编码,搜索故障编码库,最终确定故障类型.通过仿真研究,验证了该算法的可行性与有效性.     

中心二次曲线的一个轨迹特征

证明了平面曲线c是中心二次曲线的充要条件为:c是到两定点连线的斜率之积为一非零常数的点的轨迹,并就此常数的变化与轨迹类型和图形形状的关系进行了讨论.     

用迈氏干涉仪测钠光灯双黄线波长差的实验研究

结合不确定度的有关概念及相关计量规范要求,对利用迈氏干涉仪测钠光灯双黄线波长差的测量结果进行了标准不确定度评定。     

不同恶化程度胃癌细胞系的细胞间隙连接通讯功能及Cx43表达的差异

以人正常胃黏膜上皮细胞系GES-1和不同恶化程度的人胃癌细胞系(低恶化AGS细胞系、中恶化SGC-7901细胞系、高恶化BGC-823细胞系)为研究对象,采用激光共聚焦显微镜的荧光漂白恢复技术及划痕标记荧光染料示踪技术研究不同恶化程度的胃癌细胞系细胞间隙连接通讯(Gap junctional intercellular communication,GJIC)功能的差异;采用荧光定量PCR技术和间接免疫荧光技术检测间隙连接蛋白(Connexin43,Cx43)基因在mRNA和蛋白水平的表达差异,探求其与胃癌恶性程度的相关性.结果表明,在正常胃细胞系和低、中及高恶化胃腺癌细胞系中,细胞间的GJIC功能随着恶性程度的升高而减弱(AGS、SGC-7901)或消失(BGC-823),且Cx43蛋白及mRNA的表达量随着恶性程度的升高而下调(AGS、SGC-7901)或缺失(BGC-823).这提示胃癌恶性程度与胃癌细胞的GJIC功能显著相关(P<0.05),GJIC在胃癌发生中起重要作用.     

Preparation of monoclonal antibody based indirect competitive ELISA for detecting 19-nortestosterone residue

19-Nortestosterone (NT) has been illegally used in horse racing to boost physical performance, and in animal husbandry to accelerate weight gain. To monitor the abuse of NT, our goal was to develop a commercial enzyme linked immunosorbent assay (ELISA) kit. For this purpose, hybridomas were prepared by fusing NS0 mouse myeloma cells with splenocytes isolated from immunized BALB/c mouse. Noncompetitive and competitive indirect ELISA were used to screen positive cell clones. To optimize the indirect competiti...     

小麦三雌蕊基因Pis1的多效性研究初报

利用小麦三雌蕊突变体与绵阳29杂交,再以绵阳29为轮回亲本,多次回交,并结合人工选择,构建了小麦三雌蕊性状的近等基因系.对小麦三雌蕊突变体,绵阳29以及小麦三雌蕊性状近等基因系的小穗数﹑穗长﹑穗粒数﹑叶长﹑叶宽﹑茎粗﹑千粒重和单株粒重等8个农艺性状进行了分析,结果表明:其中除小穗数和穗长没有显著性差异,其余6个农艺性状均表现出显著性差异.近等基因系在穗粒数、叶长、叶宽、茎粗和单株粒重这5个农艺性状明显高于轮回亲本,而千粒重明显低于轮回亲本.由此可见Pis1基因有增加穗粒数、叶长、叶宽、茎粗和单株粒重的效应,有降低千粒重的副效益.     

单片机系统中复合键和一键多功能的设计

为节省I/O线和时间、降低成本、简化键盘软件设计,提出了一种新型单片机系统的设计方法,设计简单了复合键,利用AT89S51单片机内部两个16位可编程定时器/计数器的中断计数功能实现了一键多功能,给出其硬件电路和软件设计。     

Avian mortality due to power lines in the Canary Islands with special reference to the steppe-land birds

Biodiversity is being lost worldwide at an increased rate particularly as the result of human activities and infrastructure. Avian mortality through collision with power lines has been an important topic in animal ecology research, but studies of this kind have never been undertaken in the Canary Islands, a volcanic archipelago located near the northwest African coast that has important seabird colonies, several endemic bird species and endemic races of steppe-land birds of conservation concern. During two contrasting periods in 2008 (breeding vs post-breeding), a total of 366 km of power lines were surveyed on this archipelago covering the entire distributional range of the most important steppe-land bird species (i.e. 232 km, Fuerteventura; 134 km, Lanzarote). In all, 310 carcasses representing 23 families and 26 species were detected. We estimated with distance Sampling that 25.5% and 6.3% of individuals of the total population of Houbara bustards, Chlamydotis undulata fuertaventurae, and Eurasian stone curlews, Burhinus oedicnemus insularum, respectively, were killed in a year. We encourage the Canary Islands authorities (Consejería de Medio Ambiente del Gobierno de Canarias) to try to minimize the Houbara bustard collision rate, particularly in the northern plains of Lanzarote (i.e. Jables de Famara), as a means to reduce mortality of this emblematic species in this insular environment.