缺陷对变频牵引电机定子绕组绝缘的影响

变频调速系统引起了牵引电机定子绕组匝间电压分布不均。针对变频牵引电机的绝缘结构,采用有限元方法,仿真了定子绕组的电场分布特性。仿真结果表明,定子绕组首匝承受的电场强度最大,且匝间绝缘含有气隙或金属时,会不同程度地增大场强,降低绝缘介质的起始放电电压。该结果为变频牵引电机定子绕组的绝缘设汁提供了理论依据。     

我国海洋水下工程技术的发展与展望

从阐述海洋水下工程技术的概念内涵着手,评估了国内外海洋水下工程技术的发展状况,并依据对我国海洋水下工程技术的需求和研发资源的分析,提出了未来10年我国海洋水下工程技术的研发重点和若干建议.     

碾压混凝土在我国道路建设中的意义及工程应用

道路碾压混凝土是一种新型筑路材料，有助于缓解当前我国建设需求与建设资金、资源等矛盾。在介绍道路碾压混凝土及国外应用动态的基础上，论述碾压混凝土在我国道路建设中的重要意义；通过对近年来我国道路碾压混凝土典型工程实例的分析，探讨碾压混凝土在我国道路面层、基层、路基工程中的应用。     

高速列车在桥梁上行驶时空气动力特性的数值模拟研究

利用国际上通用的流体力学计算软件FLUENT作为研究工具,对高速列车在地面和桥梁两种行驶状态下的外部流场进行了数值模拟,分析桥梁的存在及其特征尺寸对列车气动力的重要影响。通过比较列车在不同高度、不同宽度及不同横截面形状桥梁上行驶时的气动力情况,得出针对本文选定的桥梁设计方案,桥梁的存在增大了列车倾覆危险性的结论;同时发现存在一个最危险桥梁宽度,此时列车尾部抬升和倾覆的危险最大,而当桥梁宽度增大到一定数值后,桥梁的存在将不影响列车受力;另外肯定了桥梁横截面形状接近流线型对改善列车受力有积极作用。     

锅炉水位监测系统的设计与实现

介绍锅炉水位监控系统的组成和结构,采用有效的水位显示、监控、故障预测和报警方法,实现水位信号的高精度采集和处理,监测系统安全可靠且原理简单明确,能很好地适用于船用锅炉水位的实际监测。     

设计参数对斜坡桥基承载能力的影响分析

采用有限单元法，通过改变影响斜坡桥基承载能力的各设计参数，对不同斜坡坡角、桩径、桩长、桩身材料以及岩石特性情况下桥基的承载能力进行研究，得出了各有关参数对斜坡桥基承载能力的影响规律，对斜坡桥基的设计具有一定的指导意义。     

EFFECT OF FUNDUS PIGMENT ON RESPONSE OF RABBIT RETINA TO TRANSPUPILLARY THERMOTHERAPY

Objective To study the effect of fundus pigment on the response of the retina to transpupillary thermotherapy (TTT). Methods The retina were irradiated with 810 nm diode laser in 16 eyes of 8 pigmented rabbits and 12 eyes of 6 albino rabbits. The spot size was 1.2 mm; the duration was 60 s; and powers were 50, 80, 150 and 300 mW for pigmented rabbits and 800, 1 200 and 1 500mW for albino rabbits. All of the eyes were followed up with ophthalmolscope. The fundus was photographed and examined histologically with optic microscope immediately and 1 month after TTT respectively. Results The changes of the fundus and the histological examination were not significant immediately and 1 month after TTT in 50 mW group of pigmented rabbit and 800 mW of albino rabbit. Grey spot on the retina was observed on the fundus in 80 mW group of pigmented rabbit and 1 200 mW of albino rabbit immediately after TTT. The structure of the retina remained intact and subretinal fluid was observed histologically. Grey spot was still visible on the fundus, though the fluid was absorbed after 1 month. As the power of diode laser was increased to 150 mW for pigmented rabbits and 1500 mW for albino rabbit, fundus white spots were observed and the outer retina was destroyed while photoreceptors existed immediately after TTT. Pigmentation was found in white lesions and the fibrous proliferation was found in choroid 1 month after TTT. Prominent white spot was seen on the fundus immediately after laser irradiation of 300 mW in pigmented rabbits and the structure of the retina was obscured. One month after TTT, dense pigmentation appeared at laser lesions. The retina was thinner. There was prominent fibrous proliferation in the choroid. Conclusion The fundus pigment seems to play an important role in the response of the retina to TTT. The reaction of the retina is in proportion to the intensity of laser.     

旧高桩码头基桩承载力的计算与测试

首先采用ANSYS软件对某高桩码头的原构件及基桩承载力进行有限元分析;然后模拟试验预定的加载步骤分多次施加荷载,获得了相应荷载作用下码头试验段各构件的内力及群桩中的单桩承载力;最后在码头结构上进行加载试验,测出相应的内力及单桩承载力,并与计算结果进行了比较,结果表明,采用计算与测试相结合的方法能较准确地评估码头各构件及群桩的承载能力。     

浙江省沿海港口群集疏运系统整合研究

分析港口群集疏运系统整合的必要性,并以浙江省沿海港口群为例,提出局部区域港口和港口群2个层次的整合方案,运用专业的区域战略货运分析软件STAN对整合方案实施前后的网络流量与费用进行评价,最后提出相应的整合建议。     

地下连续墙水平位移的一种近似解法

选取一地下连续墙的简化模型,引入合理的地下连续墙水平位移函数,运用最小势能原理导出了其水平位移的一种近似解法。与有限元法进行比较,计算结果比较吻合,然而此方法较为简便。