基于免疫抗体生成算法的电力变压器故障诊断

提出了一种基于人工免疫的抗体生成算法,并将其应用于电力变压器的故障诊断。抗体生成算法仿生生物免疫系统中抗体对抗原的识别与记忆的机理,先对训练样本进行免疫学习和记忆,提取表征样本的有效特征,形成表征样本特征的记忆抗体集,再用最邻近分类法对测试样本进行分类识别。UCI的Iris数据集和电力变压器故障数据的仿真分析结果表明,抗体生成算法能够进行有效的分类,并具有很高的准确率。     

基于有限体积法的G4-73型离心风机三维流场数值模拟

基于有限体积法,利用Fluent软件对G4-73型离心风机内部流场进行了全三维数值模拟。结果表明:蜗壳内的低能流体区沿轴向朝流动方向推进;叶轮内的静压和动压在叶片吸力面靠近叶轮进口处最低,叶轮流道中动压等值线呈"凸"型分布,在叶片压力面靠近叶轮出口处静压和动压达到最大值,且叶轮出口相对总压损失集中在吸力面和前盘侧。     

Mixed convection heat and Mass transfer in a vertical channel with film evaporation

Numerical results are presented for effects of latent heat transport associated with film vaporization on laminar mixed convection heat and mass transfer in a vertical channel with a half channel width b = 0.01 m. The influences of the inlet liquid mass flowrate and wall temperature on the film vaporization and the associated heat and mass transfer characteristics are examined for air-water and air-ethanol systems with gas Reynolds number Re_g = 2000. Predicted results obtained by including transport in the liquid film are contrasted with those where liquid film transport is neglected, showing that the assumption of an extremely thin film made in Lin et al. (1988) and Yan and Lin (1989) is only valid for systems having small liquid mass flow rates. Additionally, it is found that the interfacial heat flux is predominantly determined by latent heat transfer connected with film evaporation.     

Novel fluorescent polynorbornenes with multi-functional armed structure by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization and atom transfer radical polymerization

Novel organosoluble fluorescent polynorbornenes with multi-functional armed structure were designed and prepared by using highly stable block macroinitiators via a combination of living ring-opening metathesis polymerization (ROMP) and atom transfer radical polymerization (ATRP). A bromo-containing functional norbornene (NBMBr) was prepared from the Diels-Alder reaction of cyclopentadiene and allyl bromide. The diblock copolymer of 5-(N-carbazolyl methyl)bicycle[2.2.1]hept-2-ene (CbzNB) and NBMBr was successfully prepared using living ROMP and used as a novel macroinitiator [poly(CbzNB-b-NBMBr)] for ATRP. Carbazoyl-containing multi-functional armed copolymer with poly(methyl methacrylate) (PMMA) was prepared by using poly(CbzNB-b-NBMBr) as a macroinitiator for ATRP. Strong fluorescence emissions (370-450 nm) were observed in the low excimer-forming multi-functional armed fluorescent polynorbornenes. The fact is that low excimer-forming carbazole-containing polymeric compound would apparently be favorable in photoconductive materials. The multi-functional armed structure make this compound an attractive candidate for applications as multi-modified hole transport materials in molecular electronic devices. Multi-modification could be further considered to be carried out by using such a functional bromo group at the end of multi-arms.     

光化学反应中的磁场效应 Ⅱ.电子转移光敏化1,2-二苯乙烯的顺反异构化反应

前文报道了外加磁场对吸附在硅胶表面上的芳砜光解反应的影响,本文报道外加磁场影响光化学反应的另一个例子——电子转移光敏化1,2-二苯乙烯的异构化。 近年来电子转移光敏化反应引起了有机光化学家们的极大注意。一些异构化、重排、裂解、氧化反应都可以通过电子转移机理敏化。电子转移光敏化的机理可以用(1)描述。图中A和D分别代表电子的受体和给体。     

铝电解槽添加锂镁盐工业试验研究

本文论述了在20kA侧插自熔铝电解槽中添加锂盐、镁盐及锂镁盐复合剂的试验过程和技术经济效果。认为在铝电解槽中添加上述盐类在技术上是可行的,在经济上是有利的。对提高铝电解槽的电流效率和降低直流电单耗具有显著作用。     

Design of the low power wake-up receiver for internet of things communication

A wake-up receiver with high energy efficiency and low power consumption is proposed for solving the power consuming problems of wireless nodes communication in the Internet of Things. The proposed wake-up receiver based on the wake-up mechanism can effectively schedule the network nodes communication, and use the simple envelope detection structure to achieve frequency down-conversion, which can flexibly manage energy and reduce power consumption. Based on UMC 65nm CMOS process technology, the wake-up receiver is designed and simulated. The results show that it can achieve S₁₁ of -21dBm and a sensitivity of -75dBm at a data rate of 1Mb/s, when operating at the central frequency of 780MHz and input signal adopting an on-off keying (OOK) modulation, and the power consumption is 82μW at 1.2V voltage supply.     

A customised approach to determining the geomorphic effectiveness of small flood events in a regulated river

The construction of dams significantly alters flow and sediment regimes with subsequent deleterious effects on the morphological and ecological character of rivers. Effective experimental floods can ameliorate the downstream geomorphic impacts of dams. The traditional view is that large floods are required to perform effective geomorphic work, and the geomorphic outcomes of small floods are often overlooked. Many river restoration frameworks do not consider small floods. Yet, there is evidence that the hydrological characteristics that ameliorate specific geomorphic impacts in a river are unique to each river, and a customised approach to setting the right mix of floods (including small experimental floods) is needed. In this study, we modify an existing flood effectiveness model developed for large floods, for determining the geomorphic effectiveness of small floods in a highly regulated Australian river. Two flood classes were added to the model (medium peak stream power and moderate total energy expenditure), and the flood power characteristics were rescaled to reflect the relative difference in the magnitude of the small floods and the magnitude of the geomorphic work performed. Using a step‐wise approach, this customised model determined the geomorphic effectiveness of small floods. The best flood for ameliorating the geomorphic impacts of flow regulation had medium to long duration (10 to 51 days), high peak unit stream power (77 to 123 Wm^?2) and moderate to large total energy expenditure (78,600 to 342,320 × 10³ J). This approach to determining flood effectiveness for small floods is applicable to other geomorphically impacted river channels downstream of dams and can be used to inform experimental flood releases for geomorphic outcomes.     

基于表面反应和扩散迁移控制的灰岩单裂隙渗流—溶解模型及其数值模拟

针对碳酸盐类可溶岩地区水电站坝址流场、化学场以及固相介质属性等随时间发生改变,从而对工程安全运行造成不利影响等问题,研究了灰岩地区地下水运移过程中各物理场间的相互作用,分析了影响灰岩溶解速率的两个因素,即表面反应控制和扩散迁移控制。在此基础上,建立了单裂隙中的渗流—溶解耦合模型,并进行数值求解。模拟结果表明,在垂直裂隙延伸方向,其溶蚀锋面为非齐整平面,而是呈似“虫洞”状非均一变化,而沿裂隙延伸方向即自上游侧向下游方向溶蚀程度逐渐减轻;而通过裂隙的流量呈现随时间逐渐增大的趋势,但变幅不大;根据流量求得的等效水力隙宽,其增幅和增长速率均小于实际平均隙宽;同时,化学场中Ca2+浓度的分布与裂隙开度变化具有相似性,不同时刻下上游侧反应速率R均大于下游侧。就反应机制而言,在初期均受表面反应控制,而随反应进行,位于上游补给区部位转为受扩散迁移控制,但在下游位置仍受表面反应控制。     

析架空输电线路上倍容导线的选择

架空输电线路项目扩容改造,当采用倍容导线时,需在技术和经济上对倍容导线进行比较分析。文章对这种导线的种类、特性情况作了介绍,通过在220kV线路上对倍容导线的选择分析,为同类案例的处理提供了借鉴和参考。