基于BP神经网络的故障诊断技术在装备维修中的应用

传统故障诊断方法在装备保障中的诸多局限性。文章介绍了基于BP模型的神经网络,研究了基于BP模型神经网络的故障诊断推理方法,并利用Matlab仿真软件对结果进行了运行和计算。结果证明,基于BP神经网络的故障诊断技术对装备故障诊断是行之有效的。     

高强度钢作为汽车轻质材料的应用

为适应来自能源、环境与安全方面的新挑战,汽车轻量化是最有效的措施。文章主要介绍了应用在汽车上的轻质新材料———高强度钢的特性、基本分类及其在汽车轻量化设计中的应用和高强度钢相关的一些国际研究项目。     

An overview of buckling and ultimate strength of spherical pressure hull under external pressure

The load-carrying capability of spherical shells under external pressure has been the subject of a long history and many theoretical and experimental studies have been carried out. However, from a comparative study on the design rules for the minimum thickness of the deep manned spherical shells from various classification societies, significant differences have been found. This indicates that these design rules need to be updated and unified like Common Structural Rules for tankers and bulk carriers. In order to lay a foundation for this target, a systematic study is carried out to develop a consistent calculation method for predicting the ultimate strength of spherical pressure hull under external pressure. This is the first paper of a series of three for reporting this study and in this paper, a critical review on the buckling and ultimate strength of spherical pressure hulls is carried out and further problems to be studied are identified. This could lay a solid foundation for the further study.     

对超大型船舶实施护航拖轮监护的探讨

分析了宁波-舟山港南航道弯曲复杂、狭窄难行的安全风险。阐述了对超大型船舶实施护航拖轮监护的必要性和可行性。得出结论:采用护航拖轮对超大型船舶实施监护是一种安全高效的减少航行风险的措施。最后提出了对超大型船舶实施护航拖轮监护的初步方案。     

GAP-43在发育大鼠中枢神经系统的表达

目的　研究神经生长相关蛋白质 (GAP 43 )在发育大鼠中枢神经系统的表达及其意义。方法　选取生后 5、1 5、3 0d正常雄性新生鼠 ,应用免疫细胞化学ABC法结合图像分析对其大脑皮质、海马及小脑皮质GAP 43表达进行研究。结果　生后 5d ,GAP 43主要分布在神经元 ;生后 1 5、3 0d ,则分布在神经纤维网中 ,神经元胞体 (包括锥体细胞、颗粒细胞和浦肯野细胞等 )不染色 ;图像分析显示不同日龄新生鼠不同脑区GAP 43灰度值无显著性差异。结论　GAP 43是轴突生长、延伸的重要因子。     

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