Discussion on the design value of environmental condition in offshore structure design

Return period is generally adopted to calculate the design value of environmental condition in offshore structure design. However, it can not make relevant adjustment according to structure's, especially the mobile unit's, life time or its operation areas and usually make the design either insufficiently safe or rather uneconomical.A formula is developed to solve this problem in the case of the design wave height, where the risk, the design life, the distributions of wave heights in operation areas and the operating durations in each area are regarded as parameters. The applications of this method and the comparisons with the general method are presented. The result of this method is considered to be proper.     

A loss-tolerant group key management scheme with revocation capability for wireless sensor network

A new group key management scheme against the unreliable wireless communication channel and unsafe environment was proposed for wireless sensor network (WSN). In the proposed scheme, broadcast polynomial, generated over finite field Fq based on the secret sharing, was employed to revoke compromised sensor nodes. In order to tolerate key-update message loss, group session keys were generated as one-way hash chain sequence and distributed in advance. The analysis showes that the scheme has better performance in terms of the computation and communication overhead.     

Bias current influence on the characteristic of the magnetic-controlled switcher type fault current limiter

A novel magnetic-controlled switcher type fault current limiter (FCL) for high voltage electric network is presented. The current limiting principle of the FCL and the bias current influence on the characteristic of the FCL are discussed. The experiments on the 220 V/50 A test model show that the FCL can limit the fault current swiftly and effectively. Under the normal state, the bias current adjustment can change the FCL voltage loss; under the fault state, the steady fault current can be easily adjusted to the preset level by bias current regulating. The experimental result is in accordance with the principle analysis and the FCL has the advantages of flexible control strategy and simple and reliable structure. Foundation item: the National Basic Research Program (973) of China (No. 2005CB221505) and the Research Fund for Doctoral Program of High Education of China (No. 20050248058)     

F1赛车气动特性的CFD仿真和试验研究

选用Realizable k-ε模型和非平衡壁面函数,建立一款F1赛车的外表面及其外流场模型,对其进行流体动力学仿真,求得气动阻力和升力系数,并与风洞试验结果做了比较.结果表明:CFD仿真结果和风洞试验结果很接近,且该款F1赛车具有较好的气动特性.     

雌激素受体在肝海绵状血管瘤中的表达及意义

采用免疫组化Ｓ Ｐ法检测３０ 例肝海绵状血管瘤（Ｃａｖｅｒｎｏｕｓ ｈｅｍ ａｎｊｉｏｍ ａｏｆｌｉｖｅｒ,ＣＨＬ）组织中雌激素受体（Ｅｓｔｒｏｓｅｎ ｒｅｃｅｐｔｏｒ, ＥＲ）的表达,并以ＣＨＬ瘤旁正常肝组织作对照。结果ＥＲ 阳性表达于ＣＨＬ 血窦内皮细胞胞浆中,阳性率为４３３％ ;ＣＨＬ瘤旁正常肝组织中未见表达（ Ｐ＜ ０．０５）。提示肝海绵状血管瘤的生长与雌激素有关。雌激素可能通过其受体作用促进ＣＨＬ生长     

损伤失效分析的数值原理及有限元列式

结构构件在外荷载的作用下,其材料逐渐衰变,表现出损伤演化进而最后失效的行 为,描述这一行为的损伤本构关系非常复杂并且有高度的非线性;本文基于连续损伤 力学(。ntinuuln压甘以seMechan油),提出用于结构损伤失效分析的数值原理,包括损 伤模型、失效准则、结构分析变分原理及相应的有限元列式;涉及到具有损伤翔合的 弹塑性问题及蠕变问题.      

适用于上海的海绵城市建设技术分析

上海作为人口数量多、经济实力强的全国超大城市,具有地下水位高、土地利用率高、不透水面积比例高和土壤入渗率低的典型区域特点,传统的海绵城市建设技术及参数在上海的适用性受到限制。结合上海自身特点和实际需求,在国内外海绵城市建设技术分析基础上,针对性提出适用于上海的源头控制、中途转输和末端排放海绵城市建设技术,为上海市海绵城市建设提供技术支撑。     

不同温度下锂离子电池存储性能研究

本文对锂离子电池在不同温度下的存储性能进行了研究,并对存储前后电压、内阻和阻抗变化进行了分析。结果表明,25℃、45℃和55℃存储241天后容量保留率分别为91.47%、80.19%和73.21%,而在65℃存储150天后仅剩70.34%。在存储过程中,除了发生副反应,电解液和集流体等电池组成部分都会发生一定程度的恶化,当温度越高时,其恶化越严重。     

基于变速发电的直流电站电力推进系统

本文研究了一种基于变速发电的直流电站电力推进系统,分析了直流电站电力推进系统的拓扑结构,系统采用模块化的设计和集中式的布置,在此基础上对直流电站电力推进系统的技术优势进行了分析和比较,同时提出了系统的关键技术和进一步的研究内容。     

塑料模型沙干密度测试方法

塑料模型沙在航道物理模型试验中得到广泛应用,是物模试验的关键材料之一,其物理性能的准确度对物模试验的参数设置及试验结果分析尤为重要。干密度就是反映塑料模型沙重力特性的一个非常重要的物理指标,其取值准确与否直接影响物模计算结果及河床冲淤变化分析。分别对传统的测试干密度的环刀法和量筒法两种方法进行了研究,根据试验数据提出了改进措施,较大程度地提高了测试结果的准确性和稳定性。改进后的环刀法和量筒法具有一定的创新性,并得到了试验验证,可为相关行业的塑料模型沙试验提供指导和依据。