新型等效源法的理论分析及其应用

将等效原理和分离变量法结合,提出了求解电磁场的新型等效源法。该方法的通解形式为无穷级数,在该方法中有确定等效源位置的具体方法和原则,这些方法和原则完全适用于模拟电荷法及广义多级技术,并使它们从经验的约束中解脱出来,从与模拟电荷对闭合场计算结果的比较中可明显看出新型等效源具有许多优点。     

避雷器热等价性及复合外套避雷器稳态热特性初探

金属氧化物避雷器的热特性决定着避雷器长期带电运行的稳定性。通过对避雷器最新标准中关于热特性相关内容的解析,指出了避雷器的热特性实质包括了稳态热特性和瞬态热特性,验证比例单元与避雷器具有稳态热等价性是进行动作负载等试验的前提,给出了试验项目与评价热特性的关系,同时指出了现有标准中在试品选取方面的某些不妥。通过试验研究了复合外套避雷器的稳态热特性,给出了几点常见的热特性规律。     

接地装置冲击大电流试验系统研制及杆塔接地冲击特性测试

为模拟真实雷电冲击电流在接地装置及其周围土壤中的散流过程,准确掌握接地装置的冲击特性,研制了接地装置的冲击大电流试验系统。在大量仿真计算和系统方案论证的基础上,提出了围绕直径40m圆环形回流电极均匀对称布置的4台分体式冲击大电流发生器的技术方案,其中单台冲击电流发生器的充电电压可达1 000kV,该系统可在负载大于4Ω的情况下产生峰值为100kA、波形为8μs/20μs的标准雷电冲击电流。测量得到的地表、回流电极地电位升分布均匀,证实了试验冲击电流地中分布与真实雷电流地中分布的等效性。针对该系统提出了工频、冲击接地电阻的修正公式。通过试验得到了典型杆塔接地装置在8μs/20μs、2.6μs/50μs冲击电流作用下的冲击特性曲线。该曲线表明在低电阻率土壤中该装置的冲击接地电阻随冲击电流峰值的变化并不显著。     

Effects of graded dosages of alcohol on nine computerized repeated-measures tests

Abstract

We report a controlled laboratory validation experiment to provide an empirical sequel to the general background of the development of the Automated Performance Test System (APTS) that was presented in Turnage et al. (1992). The purpose of this study was to index performance deficit against various Blood Alcohol Concentrations (BACs) of small (0·05% BAC), medium (0·10% BAC). and large (0·15% BAC) dosages as well as a placebo (0·00 BAC) condition. Blood alcohol concentrations, measured in four different ways, were highly reliable and the method with the highest intercorrelation was whole blood. When taken singly, eight of the nine tests produced significant (p< 0·001) relationships with the disparate blood alcohol levels, which were essentially monotonic. A multiple regression analysis suggested that most of the tests were behaving similarly and that two or three tests accounted for 52 to 54% of the variance attributable to alcohol that was explained by the longer battery. While all tests appear valid, some of them appeared more sensitive than others (viz., code substitution, manikin, and choice reaction time). From the standpoint of these tests, greater changes occurred in cognitive function between the placebo and 0·05 level man between the 0·05 and 0·10 levels. However, the greatest reduction in performance occurred between 0·10 and 0·15, and the relatively abrupt nature of this change implies that sharp decrements in cognitive performance occur at that point. There were individual differences in resistance to alcohol, and there is strong inference that these differences would be reliable if they were tested again. We believe that further development and study of such techniques is warranted for use in fitness-for-duty testing and development of a dose equivalency index.     

一种MPLS网络中的LDP协议跟踪系统

为了解决目前Internet为主的IP主干网络所面临的问题，IETF提出了多协议标签交换(MPLS)概念。MPLS能在主干网上大大提高IP转发性能，并提供业务分类以及质量保证。而对于MPLS网络中的标签分发，是由标签分发协议(LDP)实现的，因此通过对MPLS网络中的LDP协议的跟踪，就可以掌握整个MPLS网络的运行状态；本文主要介绍一种MPLS网络中的LDP协议跟踪系统的原理和实现。     

Polycyclic Aromatic Hydrocarbons in Residential Soils from an Indian City near Power Plants Area and Assessment of Health Risk for Human Population

This article deals with the distribution, composition profiles, and possible sources of sixteen priority polycyclic aromatic hydrocarbons (PAHs) in residential soils from Korba district in Chhattisgarh State, India. Sixteen priority PAHs in soils were analyzed after ultrasonic extraction, silica gel column chromatographic cleanup, and quantitation was performed using HPLC-DAD. The concentrations of ∑16PAHs were within acceptable limits of soil quality guidelines and the study area got classified as weakly contaminated. The concentration of probable human carcinogenic PAHs in soils accounted for 10% of ∑16PAHs. The concentration of Benzo(a)Pyrene (BaP) accounted 1% to total PAHs. Benzo(a)pyrene Toxicity Equivalency (BaP_TEQ) for 16 PAHs was 30 ± 12 μg BaP_TEQ kg^?1. The composition profiles and molecular ratios of PAHs suggested mixed pyrogenic sources of PAHs from combustion of coal, wood, and vehicular exhaust emissions. Human health risk was assessed by calculating the lifetime average daily dose (LADD) and incremental life time cancer risk (ILCR) for human adults and children. Estimated ILCR was within safe limit (10^?6?10^?5), indicating low risk to human population. Potential risk to contaminated ground water from leaching of carcinogenic PAHs was assessed by estimating the Index of Additive Cancer Risk (IACR).     

混凝土物化资源耗竭影响的定量评价

简述了产品生命周期评价和资源耗竭影响,在综合资源储量、年消耗量和回收率的基础上提出了资源耗竭影响和当量系数的计算方法.通过分析几种不同强度等级的掺与不掺粉煤灰混凝土的实验,定量评价了混凝土物化能耗及资源耗竭指数.研究结果有助于绿色建筑设计合理选择混凝土强度等级和加强混凝土生产的资源科学管理.     

基于模糊聚类的属性加权算法

针对传统的模糊聚类算法(FCM)的不足,提出了具体的改进和提高的方法,使用模糊等价性理论对原始样本集进行处理以得到聚类数和初始聚类中心,通过修改聚类目标函数来提高算法处理孤立点的能力和体现样本空间各维度对聚类效果的价值,最后通过实验比较表明算法的有效性。     

特高压断路器的大容量开断试验等价性分析与开断试验方法

根据特高压断路器试验要求,对Weil-Dobke电流引入型合成试验回路的等价性进行了分析,探讨了引入电流的频率要求。介绍了ABB公司的EPIC合成试验回路,讨论了EPIC回路的结构和工作特点,指出了EPIC回路存在的问题。提出了适用于特高压断路器大容量试验的XIHARI合成试验回路,详细介绍了该回路的工作原理,对其试验等价性进行了分析。     

填埋场成层衬垫污染物运移参数等效模型

为了高效评价填埋场成层衬垫的防污性能，提出基于时间矩卷积的污染物运移参数等效分析模型. 给出多层衬垫等效渗流速度和扩散系数表达式；采用土柱实验数据验证模型的合理性和可靠性；基于衬垫系统底部相对浓度、瞬时通量及累计通量等对填埋场土工膜（GM）+压实黏土衬垫（CCL）+天然衰减层（AL）及GM+钠基膨润土防水毯（GCL）+AL不同复合衬垫进行等效计算. 结果表明，衬垫底部相对浓度更适合等效计算. 随设计水头与AL厚度增加，GCL复合衬垫的防污性能较好. 基于Cl^?击穿时间100 a标准，当水头为15 m时，与采用CCL相比，采用GCL复合衬垫可以使总厚度减少0.45 m. 土工膜防污能力随水头增加而增强，土工膜等效的CCL厚度随服役年限呈对数线性增大.