基于Ansys Workbench软件热分析的复拌机烟气管道结构设计

利用Ansys workbench软件对复拌机烟气管道进行稳态热分析,求解出管道的温度场分布和热流密度,用热一结构耦合方法将热载荷施加到结构中,得出了热应力与应变的分布规律。验证了热传导理论计算的准确性,分析了结构上不合理之处,并依据计算结果对结构进行了优化改进。再次求解的结果表明,结构改进的方法是正确的,获得了明显的效果。     

Synthesis and characterization of Cu-doped ceria nanopowders

Nanopowdered solid solution Ce_1−xCu_xO_2−γ samples (0 ≤ x ≤ 0.15) were synthesized by self-propagating room temperature synthesis (SPRT). Raman spectroscopy and XRD at room temperature were used to study the vibration properties of these materials as well as the Cu solubility in ceria lattice. The solubility limit of Cu²⁺ in CeO₂ lattice was found to be lower than published in the literature. Results show that obtained powders with low dopant concentration are solid solutions with a fluorite-type crystal structure. However, with Cu content higher than 7.5 mass%, the phase separation was observed and two oxide phases, CeO₂ and CuO, coexist. All powders were nanometric in size with high specific surface area.     

移动互联网用户标识管理技术的研究

移动互联网业务中,网络地址转换(NAT,Network Address Translation)技术使得公网增值服务提供商(SP)无法获取用户标识及其基础信息、业务使用信息,因此无法实现业务使用计费及用户管理,极大地限制了移动互联网业务的发展。文章针对这一问题,提出一种全新的移动互联网用户标识解决方案,运营商通过对用户转换前、后标识信息的匹配及对用户的统一管理,形成用户访问信息的完整记录,实现公网SP对移动互联网用户信息的识别和管理。     

Lightweight and provably secure user authentication with anonymity for the global mobility network

Seamless roaming in the global mobility network (GLOMONET) is highly desirable for mobile users, although their proper authentication is challenging. This is because not only are wireless networks susceptible to attacks, but also mobile terminals have limited computational power. Recently, some authentication schemes with anonymity for the GLOMONET have been proposed. This paper shows some security weaknesses in those schemes. Furthermore, a lightweight and provably secure user authentication scheme with anonymity for the GLOMONET is proposed. It uses only symmetric cryptographic and hash operation primitives for secure authentication. Besides, it takes only four message exchanges among the user, foreign agent and home agent. We also demonstrate that this protocol enjoys important security attributes including prevention of various attacks, single registration, user anonymity, user friendly, no password/verifier table, and use of one‐time session key between mobile user and foreign agent. The security properties of the proposed protocol are formally validated by a model checking tool called AVISPA. Furthermore, as one of the new features in our protocol, it can defend smart card security breaches. Copyright © 2010 John Wiley & Sons, Ltd.     

A Hollow‐Core,Magnetic, and Mesoporous Double‐Shell Nanostructure: In Situ Decomposition/Reduction Synthesis,Bioimaging, and Drug‐Delivery Properties

A novel in situ decomposition/reduction approach is developed to manu­facture hollow core, magnetic, and mesoporous double‐shell nanostructures (HMMNSs) via in situ decomposition and reduction of a β‐FeOOH nanorod core and organosilicate‐incorporated silica‐shell precursor. The formed HMMNSs are then aminated by silanization for further covalent conjugation to rhodamine B isothiocyanate (RBITC) and poly(ethylene glycol) (PEG) chains. The resultant RBITC‐grafted and PEGylated nanocomposites (HMMNS–R/Ps) have excellent blood compatibility and very low cytotoxicity towards HeLa and MCF‐7 cells, and can be taken up by cancer cells effectively in a dose‐dependent manner, as confirmed by in vitro flow cytometry, confocal luminescence imaging, and magnetic resonance imaging (MRI) studies. In vivo MRI studies coupled with Prussian blue staining of slides from different organs show that the nanocomposites preferentially accumulate in liver and spleen after intravenous injection, which suggests a potential application of the nanocomposites as MRI contrast agents. Importantly, the HMMNS–R/P nanocomposites show high loading capacity for water‐insoluble anticancer drugs (docetaxel or camptothecin) owing to the presence of a large inner cavity and enhanced surface area and pore volume. Furthermore, the drug‐loaded nanocomposites exhibit greater cytotoxicity than the corresponding free drugs. These results confirm that the HMMNS–R/P nanocomposites are promising candidates for simultaneous bioimaging and drug delivery.     

Tunable distributed feedback lasing from leaky waveguides based on gel-glass dispersed liquid crystal thin films

Different amount of nematic liquid crystal (LC) 4-Cyano-4′-pentylbiphenyl(5CB) was encapsulated in sol–gel derived organically modified silica(ORMOSIL) matrices to fabricate dye doped gel-glass dispersed liquid crystal (GDLC) thin films by co-hydrolyzation/condensation of ethyl triethoxisilane (ETES) and tetraethyl orthosilicate (TEOS) precursors. Distributed feedback (DFB) leaky waveguide lasers from GDLC thin films using a dynamic grating were demonstrated. Tunable laser action from 558 to 570 nm was obtained in the sample with lowest LC concentration of 0.375 mol%. The DFB laser performance of GDLC thin films with various LC concentrations was investigated using the same pumping geometry, and it was shown that the encapsulation of 5CB also led to the red shift of lasing peak.     

Effect of Solution Treatment on Thermal Conductivity of Porous NiTi Shape Memory Alloy

In this study, a new solution treatment “solution treatment under loading” was applied to a porous Ni–50 at.%Ti shape memory alloy (SMA), which was fabricated by self-propagating high-temperature synthesis (SHS), to explore the microstructural improvement regarding single-phase NiTi. The effects of solution treatment under loading and without loading on the phase constituent and thermal conductivity were investigated and discussed. The phase constituent and thermal conductivity of the specimens considerably changed with solution treatment under loading, but they were not affected significantly with solution treatment without loading. Intermetallic phases such as B19′(NiTi), Ti₂Ni, and Ni₄Ti₃ disappeared, the density of the B2(NiTi) phase increased with solution treatment under loading, and thus the thermal conductivity was increased. It was also seen that the thermal conductivity of porous NiTi was less than that of solid NiTi.     

Bi-Sn熔体在高熵合金上的润湿行为及界面特征

采用传统座滴法研究了低熔点合金(Bi-Sn)和高熵合金(AlCoFeNiCr和CuCoFeNiCr)之间的润湿行为及界面特征。借助扫描电子显微镜(SEM)和能谱分析(EDS)分析了Bi-Sn/AlCoFeNiCr和Bi-Sn/CuCoFeNiCr界面微观结构。结果表明:AlCoFeNiCr和CuCoFeNiCr高熵合金都是结构单一的固溶体,但Bi-Sn熔体在CuCoFeNiCr高熵合金基体上的润湿性明显地优于Bi-Sn熔体在AlCoFeNiCr高熵合金基体上的润湿性;Bi-Sn/CuCoFeNiCr界面发生剧烈的化学反应,有大量的界面反应物生成,Bi-Sn熔体中的原子Sn主要是沿着CuCoFeNiCr高熵合金中的富铜相扩散,而Bi-Sn/AlCoFeNiCr界面平直,且随着润湿温度的升高,Bi-Sn熔体中的原子向AlCoFeNiCr高熵合金基体的扩散程度加强并伴随化学反应,出现类似"皮下潜流"现象;由于CuCoFeNiCr高熵合金中富铜相的存在,为Bi-Sn在CuCoFeNiCr高熵合金基体上的铺展提供了"润湿通道"。     

运营中的航站楼雨、污水系统改造施工

上海浦东国际机场T1航站楼新建雨、污水管线与原有管线、新建结构、原有结构、围护体系之间的关系错综复杂,且须在不停航运营状态下完成施工作业。结合新老结构以及新老雨、污水管线的关系,根据现场实际情况制定了科学合理的施工方案,顺利完成了中庭雨、污水管的施工,满足了不停航施工要求,取得了较好的效果,对后续类似工程具有重要的借鉴意义。     

基于光散射的实时气溶胶粒子形状识别技术研究

利用米氏散射理论和时域有限差分(FDTD)软件计算了不同大小、形状和折射率粒子的前向散射光场分布,分析了通过光强度分布和非对称因子反演粒子相关信息、区分粒形的可行性。研制了一台利用增强型CCD相机在线采集单个气溶胶粒子在5°~19°前向散射角范围内光场图样的装置。8μm粒径的聚苯乙烯球形粒子散射图样实验结果与理论计算对比较为吻合,验证了该装置的有效性。应用该装置对不同形状的气溶胶粒子进行检测,结果表明能够从散射图像和反演计算结果区分出球形、杆状和其他形状粒子。