预应力混凝土用金属波纹管检测方法的改进

在预应力混凝土用金属波纹管检测经验的基础上,结合日常检测工作,对金属波纹管的集中荷载、均布荷载、集中荷载下的抗渗漏性等3大关键性指标的试验方法,提出具体的操作和建议。试验方法应尽可能地细致和明确,以避免由于方法不同而造成检测结果的差异。     

A concise overview of heliostat fields‐solar thermal collectors: Current state of art and future perspective

Heliostat field or solar tower collector is one of the most promising concentrated solar power technologies available in the market. Due to its high operating temperature, heliostat field collector can be implemented in a wide range of applications from solar power generation to industrial commodity production. There are several currently operating, under construction, and planned heliostat fields around the world. In this paper, a brief overview of the current state of the art, applications, assessment methods, future perspective, and methods of improvement are discussed.     

基于主保护不平衡电流有效值的转子匝间短路故障监测

为利用发电机主保护所配电流互感器来监测励磁绕组匝间短路故障,以三峡VGS发电机为例,采用多回路方法对故障后进入各主保护的不平衡电流进行了计算与分析;在此基础上,指出利用不平衡电流中的单次谐波进行故障监测的不足,由此提出基于主保护不平衡电流有效值的励磁绕组匝间短路故障监测原理;通过对不同短路匝比故障的计算与理论分析,指出...     

模块化绕组在小型永磁风力发电机中的应用

针对1000 W的永磁风力发电机,采用电磁场有限元分析软件Magnet分析了给定的性能指标及主要尺寸下,不同的集中绕组结构对发电机空载电动势和起动阻力矩的影响。结果表明,采用24槽/22极模块化绕组方案,发电机空载电动势的正弦度高,起动阻力矩小。分析结果对小型永磁风力发电机的绕组设计具有一定参考价值。     

五相感应电动机定子绕组匝间短路仿真分析

建立了五相集中整距绕组感应电动机定子绕组匝间短路时的统一模型.通过该模型,可以分析定子各种短路故障及各电机参数对定子绕组匝间短路的影响.针对电机一相出现匝间短路时的情形,利用Matlab/Simulink 进行了仿真计算,通过对比Ansoft场路耦合计算结果,可以发现,两种结果是相吻合的,在一定程度上验证了所建立模型的...     

电机绕组滚动烘干炉防爆安全技术探讨

电机绕组滚动烘干工艺在电机行业中逐步推广应用,但该防爆滚动烘干设备的制造却仍没有统一的标准,这就为设备的制造、使用、维修、保养埋下了隐患.文章主要探讨了防爆滚动烘干炉的防爆技术,以期引起同行对防爆滚动烘干炉设备安全的关注.     

Catalytic conversion of concentrated miscanthus in water for ethylene glycol production

Miscanthus, a promising energy crop, was used for ethylene glycol (EG) production through one‐pot catalytic conversion. With a binary catalyst composed of commercial tungstic acid and Raney Ni, the miscanthus with 1 % concentration was transformed into EG with a yield of 35.5%. However, the yield dropped to 13.6% as the miscanthus concentration was increased to 10 %. The underlying reason for the yield decrease was disclosed through analysis of the liquid products, investigation of pretreatments, and characterization of the catalysts. It was found that the protectors on the surface of miscanthus and the lignin component underwent decomposition under reaction conditions, resulting in the formation of some organic acids and unsaturated compounds that preferentially poisoned the Raney Ni catalyst and consequently decreased the EG yield. When the inhibitors were effectively removed by base solvent pretreatment, the EG yield was successfully improved to 39.0% even under 10% concentration of feedstock. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2254–2262, 2014     

基于分布式光纤温度监测系统的集中渗漏通道流速计算模型

分布式光纤测温系统因其造价低、可实现实时快速分布式测温等优点,在堤坝渗漏监测方面具有良好的应用前景。但由于缺乏必要的理论基础和试验研究,目前分布式光纤测温的应用仅局限于渗漏定性分析,缺乏定量计算研究。根据分布式光纤温度监测系统在不加热和加热两种情况下的温度测量值,利用热平衡理论及坝体周围岩土体温度变化与集中渗漏流速关系建立数学物理模型,在层流和紊流两种不同流态下探讨了渗漏流速的确定方法。经过一个实例计算,验证了所推导公式的正确性,为分布式光纤测温在渗漏监测中的应用,提供了一个定量分析的依据。     

基于SPE-HPLC的浓缩苹果汁中棒曲霉素检测方法的研究

棒曲霉素是真菌代谢所产生的一类有毒化合物,多存在于霉烂的苹果中。最常用的检测方法是利用各种液液萃取分离步骤来提取苹果汁中的棒曲霉素。在本研究中,两种固相萃取柱:C18-SPE和亲油亲水平衡大孔聚合吸附柱(HLB),被用来萃取分离浓缩苹果汁中的棒曲霉素。高效液相色谱(HPLC)检测用反相C18色谱柱,紫外检测器,检测波长276nm。在加标10～100μg/L的水平下测得棒曲霉素回收率分别为C18-SPE 87.56%～88.4%、HLB-SPE 85.45%～88.76%、LLE 79.47%～80.1%,变异系数分别为3.28%～4.47%、4.32%～7.15%、6.28%～7.67%。     

变压器铁心发热故障的分析与处理

电力变压器是电网运行的"心脏",根据变压器运行的实际情况,较为全面的介绍了变压器几种铁心故障,分析了其故障原因,并针对各种故障类型分别给出了相应的解决方案,对变压器运行常见故障以及故障查找、解决方法等都有一定的参考意义。