组合神经网络在结构损伤检测中的应用

子结构的动态响应变化与整体结构相比,对结构内部损伤反应更为敏感。组合神经网络可以克服单个神经网络功能的单一局限性,实现更加全面综合的仿真识别功能。本文首先运用双协调自由界面模态综合法对结构进行模态分析,获取各子结构及整体结构的模态信息。然后,通过组合BP神经网络将损伤子结构与整体结构的模态频率变化率组合起来进行结构损伤检测。该方法在改善网络训练性能的同时,提高了检测结果的准确性和可靠性。文章最后通过数值算例验证了该方法的可行性和有效性。     

Sequence analysis of the gene correlated with cytoplasmic male sterility (CMS) in rape-seed (Brassica napus) Polima and Shaan 2A

orf224 is a CMS-related mitochondrial gene discovered in Polima cytoplasm. Shaan 2A CMS line is the parent of the first rapeseed hybrid cultivar Qinyou No. 2that has been grown in many regions of China. In this work,genomic DNA of Polima CMS line and Shaan 2A CMS line were used as templates, two primers of specific oligonucleoamplification fragments were cloned into pGEM-T Easy vectors and DNA sequences were determined. The CMSassociated gene, orf224-1 present in Shaan 2A CMS line, has a sequence highly homologous to the orf224 of the Polima CMS line, except for one nucleotide at position +398. There were only one base (AAC→AGC) and one amino acid (Asn →Ser) differences between the two. The homologies of the two sequences in nucleotide and. amino acid were 99.9 % and 99.6%, respectively. It is concluded that orf224 in Polima CMS line and orf224-1 of Shaan 2A CMS line are the allele at the same locus in mitochondria.``     

Fluoropolymer materials and architectures prepared by controlled radical polymerizations

This review initially summarizes the mechanisms, merits and limitations of the three controlled radical polymerizations: nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP) or metal catalyzed living radical polymerization, and reversible addition-fragmentation chain transfer (RAFT) polymerization. This is followed by two parts, one dealing with homo- and copolymerizations of fluorinated methacrylates and acrylates, and a second where fluorinated styrenes, alone or in combination with other monomers, are the main issues. In these parts, initiators (including multifunctional and macroinitiators), ligands and other reaction conditions as well as some kinetics and conversions are discussed. Numerous possibilities for preparation of a variety of different block copolymers where one or more blocks are fluorinated are devoted particular attention. The advantageous properties and functionalities that can be obtained from these novel fluorinated materials and architectures are especially emphasized. Thus, various amphiphilic, biocompatible or low energy materials, fluorinated nanoparticles and nanoporous films/membranes as well as materials for submicron and nanolevel electronics have been fabricated. In addition, the possible fluorination of various surfaces through surface initiation is highlighted. A final part deals with the use of fluorine containing initiators and macroinitiators, and the applications on the novel materials derived thereof.     

Machine reliability and preventive maintenance planning for cellular manufacturing systems

The paper proposes a preventive maintenance (PM) planning model for the performance improvement of cellular manufacturing systems (CMS) in terms of machine reliability, and resource utilization. In a CMS, parts are processed by a group of interdependent machines, where machine reliability plays an important role in the performance improvement of the cell. Assuming that machine failure times follow a Weibull distribution, the proposed model determines a PM interval and a schedule for performing PM actions on each machine in the cell by minimizing the total maintenance cost and the overall probability of machine failures. The model uses a combined cost and reliability based approach, and optimizes maintenance costs by administering a group maintenance policy subject to a desirable machine reliability threshold. The study also proposes a CMS design model that integrates the above PM concepts into the design process. Illustrative examples are presented to demonstrate the applicability of the proposed approach.     

Studies of the energy release of mitochondria from sporophyte cytoplasmic male sterile rice by differential scanning calorimetry

The differential scanning calorimetric (DSC) curves of the mitochondria isolated from two varieties of sporophyte cytoplasmic male sterile and their fertile lines of Yie Bai and Ma Xie type rice have been determined. The curves show that the energy is released continuously as temperature rise to 70°C. Some thermodynamic and kinetic parameters of the energy release of the mitochondria have been obtained. The presented results showed that the mitochondria from cytoplasmic male sterile rice released more heat and they had higher energy barrier, less rate, and more complicated mechanism than that of their fertile lines in the energy release process. Foundation item: Supported by the National Natural Science Foundation of China, the China Postdoctoral Science Foundation Biography: Zhou Pei-jiang (1956-), male, PhD, Associate professor. Current resarch interest is in biophysical chemistry and environmental ecological chemistry     

Early physics with ATLAS and CMS

The status of the CMS and ATLAS experiments is given, as it is end of 2007. A quick tour of possible new physics is presented.      

Quantification of a Ti(CxN1−x) based multilayer by Auger Electron Spectroscopy

Auger Electron Spectroscopy (AES) is an analytical technique sensitive to the surface of materials and providing elemental and chemical composition of conductive samples. The excellent spatial resolution and its quantification possibilities, even for light elements, make AES a commonly used technique to investigate surface and interfaces.TiN-like materials have a wide range of applications depending on their stoichiometry, but their composition is still complex (or at least not straightforward) to determine because of a strong overlapping of the Ti LMM with the N KLL Auger transitions. This quantification problem can be circumvented using computerised calculations as target factor analysis (TFA) to estimate the different nitrogen and titanium contributions in this peaks overlap. However, a more simple method, based on the study of Ti LMM and Ti LMV area ratio of pure TiN and TiC reference samples, is described in this paper and can be used to obtain the atomic composition of any titanium nitride based compound, whatever the complexity of the material. This method is an alternative to easily quantify TiN-like compounds by AES.As an illustration, a Ti(C_xN_1−x) based multilayer deposited on a hardmetal substrate was investigated. This quantification method was successfully used to evidence three different layers and the diffusion phenomenon at the interfaces between the layers. This study was completed with a quantitative SIMS depth profile that the high sensitivity and depth resolution allowed to measure the small variations of composition lower than the uncertainty of AES.     

运用CMS建设高校信息平台

网络技术的发展和更新速度是很快的。高校的门户网站不仅是学校的窗口体现,而且是信息交流的节点。如何保持该网站的新颖和管理是一项艰巨的任务。此时的内容管理系统可充分发挥学校资源和延展性,使之满足高校师生的要求。本文从理论上充分分析了该系统的特点以及给出了解决方案。     

Feasibility study of a J/ψ cross section measurement with early CMS data

We report the methods and plans for measuring the differential cross section of J/ψ→μ+μ- production, using data to be collected in the first LHC run by the CMS detector. Making use of the large B-hadron lifetime, we show how to separate the promptly produced J/ψ's from those coming from B-hadron decays. Since the J/ψ production cross section is expected to be large, the analysis should be viable with relatively small data sets, that will become available early in the startup of the LHC. We also address effects of a non-perfect detector alignment, as well as systematic uncertainties.About 70 thousand J/ψ decays are reconstructed from Monte Carlo data, which corresponds to an integrated luminosity of 3 pb-1 in 14 TeV collisions, in the range of pJ/ψT between 5 and 40 GeV/c. The precision of the result is limited by systematic uncertainties, and is at the 15% level.     

基于CMS平台的校园网站系统设计与实观

网站群建设是目前高校网站建设的趋势。采用具有网站群管理功能的内容管理系统（Content Management System,CMS）能够有效提高网站建设和网站管理的效率。本文以目前比较流行的Drupal内容管理系统为平台来设计并实现校园网站建设。