Metallographic sample prepared by ion beam etching

Ion beam etching technique was used to reveal the metallograhpic microstructure and interface morphology of electroplating chromium coating, in particular, whose substrate surface layer was treated in advance by laser quenching. Chemical etchings were also conducted for comparison. The reveal microstructures were observed and analyzed by scanning electron microscopy. The results show that ion beam etching can reveal well the whole microstructures of composite coating-substrate materials.     

液压伺服疲劳试验机的H∞混合灵敏度控制研究

针对液压伺服疲劳试验机系统的不确定性，为获得良好的控制效果，采用了H∞鲁棒控制算法。首先，通过理论分析建立系统数学模型，讨论了该模型的不确定性及参数摄动性；然后，详细阐述了加权函数选取的一般规律；最后，应用混合灵敏度方法设计了H∞鲁棒控制器。仿真结果表明，即使被测试件刚度及系统参数在较大范围内摄动，该控制器依然具有很好的鲁棒稳定性以及良好的动态品质，较常规PID控制器更为优良。     

A SIMPLIFIED EXPRESSION OF m-n-δ RELATIONS FOR MATERIALS WITH PLASTICITY OR SUPERPLASTICITY

以Hart的微分型本构关系为基础,本文推导出了一个既包含应变硬化效应(n)又包含应变速率敏感效应(m)的m-n-δ关系式δ=[1/(1-(1-α(0))~(1/m))]~m×e~n-1当n=0时,它吻合于Ghosh和Ayres的现代分析,当m=0时,吻合于Considère的经典分析.该公式的计算结果和实验结果一致.     

Performance of positive and negative electrodes in amorphous manganese oxide supercapacitor

Using potassium permanganate and acetic manganese as the reactants, amorphous manganese oxide was prepared with mechanochemical method. XRD was used for microstructure characterization, while cyclic voltammetry and constant current charge-discharge were used for electrochemical performance testing. The positive electrode （PE） and negative electrode （NE） were investigated respectively in amorphous manganese oxide supercapacitor, aiming to find their different performances in charging-discharging. The results show that the crystalline structure is destroyed in both the PE and NE material during charge-discharge process. Thereinto, the NE suffers a bit more seriously. When cycling, the PE potential scope diminishes while the NE potential scope enlarges. The increased inner resistance makes the NE curves almost bended to be a right angle, but not the PE curves. The cell＇s equivalent series resistance （ESR） is more dependent on the NE, and the capacitance is mainly determined by the rapid descent of the NE potential range. The capacitances of the NE are highly rate-dependent, decreasing from 121.3 to 53.1 F/g, by 56.2%, over the range of 5-25 mV/s. However, the PE appears to be weakly dependent and its capacitance is only dropped by 22.1%.     

Research on graphite powders used for HTR-PM fuel elements

Different batches of natural graphite powders and electrographite powders were characterized by impurity, degree of graphitization, particle size distribution, specific surface area, and shape characteristics. The graphite balls consist of proper mix-ratio of natural graphite, electrographite and phenolic resin were manufactured and characterized by thermal conductivity, anisotropy of thermal expansion, crush strength, and drop strength. Results show that some types of graphite powders possess very high purity, degree of graphitization, and sound size distribution and apparent density, which can serve for matrix graphite of HTR-PM. The graphite balls manufactured with reasonable mix-ratio of graphite powders and process method show very good properties. It is indicated that the properties of graphite balls can meet the design criterion of HTR-PM. We can provide a powerful candidate material for the future manufacture of HTR-PM fuel elements.     

铜金粉的颜色及其影响因素

利用分光光度计对国内外铜金粉的颜色进行了测试，研究了铜金粉的成分、微观状态对颜色的影响。结果表明：铜金粉颜色可以用色彩三要素进行描述，其中铜金粉的色相只与合金成分有关，而与铜金粉片的大小、形状及粒度分布无关；明度和纯度与铜金粉片在油墨层中定向排列状态、片的大小、形状及粒度分布有关，而与成分无关；合金成分的微小波动不会引起铜金粉色相的明显改变。     

ON THE HYDROGEN STORAGE BEHAVIOUR OF ALLOYS La_2Mg_(17) AND La_2Mg_(16)Ni

制备了La_2Mg_(17)和La_2Mg_(16)Ni合金,研究了其贮氢性能。给出了这两种合金的解吸等温线,并据此计算了相应的△H,△S值。解吸等温线的分析表明:La_2Mg_(16)Ni的解吸等温线有分别对应于Mg_2Ni-Mg_2NiH_4以及Mg-MgH_2的两个平台。通过X射线衍射物相分析和电子探针分析,总组成为La_2Mg_(16)Ni的合金实际上是La_2Mg_(17)型和Mg_2Ni型两相混合物。La_2Mg_(16)Ni的氢化产物是La的氢化物以及MgH_2和Mg_2NiH_4。对两种合金还作了常温低压吸氢及常压加热吸氢等应用试验。从研究结果看来,La_2Mg_(17)和La_2Mg_(16)Ni合金是性能较好的贮氢材料。     

可组合的描述符泄露类型检查

应用程序通过操作系统的系统调用对文件描述符进行操作并管理文件资源。如果应用程序对资源描述符的管理出现错误并发生描述符泄漏,会严重影响系统的可用性。据此,提出了一种检查程序是否会导致描述符泄漏的类型系统,给出了描述符操作方法的语义和类型约束,证明了类型系统的可靠性定理。此外,还初步讨论了该类型系统在并发程序下的扩展。     

Practical chosen-ciphertext secure Hierarchical Identity-Based Broadcast Encryption

We focus on practical Hierarchical Identity-Based Broadcast Encryption (HIBBE) with semantic security against adaptively chosen-ciphertext attacks (CCA2) in the standard model. We achieve this goal in two steps. First, we propose a new HIBBE scheme that is secure against chosen-plaintext attacks (CPA). Compared with the existing HIBBE scheme that is built from composite-order bilinear groups, our construction is based on prime-order bilinear groups. The much better efficiency of group operations in prime-order bilinear groups makes our proposed HIBBE scheme more practical. Then, we convert it into a CCA2-secure scheme at the cost of a one-time signature. Instead of extending one user hierarchy in the Canetti–Halevi–Katz approach from CPA-secure (\(l+1\))-Hierarchical Identity-Based Encryption [(\(l+1\))-HIBE] to CCA2-secure \(l\)-HIBE, our construction merely adds one on-the-fly dummy user in the basic scheme. We formally prove the security of these two schemes in the standard model. Comprehensive theoretical analyses and experimental results demonstrate that the proposed HIBBE schemes achieve desirable performance.     

矿山物联网服务承载平台与矿山购买服务

矿山综合自动化系统由于没有考虑容纳第三方的服务,逐步显露出系统封闭、标准不一、信息应用困难、对矿山技术人员要求高等问题,阻碍了其发展。明确了矿山物联网的本质为服务承载平台,矿山物联网应具有相应的公共服务能力,包括基于位置的服务、基于时间的服务、基于信息的服务、基于云的服务、基于大数据的服务、基于语义的服务等,重点论述了矿山物联网应具备的服务能力和矿山购买服务,指出这些服务能力会随着技术和需求的发展而不断充实与增加,使矿山物联网逐步向智慧矿山迈进。