非晶态合金催化剂的研究进展

非晶态合金是一种新型的催化材料，对其制备，表征和催化性能方面自８０年代初期以来所取得的研究成果进行了综述，详细介绍了非晶态合金催化剂及其应用的进展。     

纳米晶材料的制备、结构性能及其进展

纳米晶材料（ｎａｎｏｓｔｒｕｃｔｕｒｅｄｍａｔｅｒｉａｌｓ）是近来发展起来的一种新型材料，其单个晶粒尺寸为纳米级，构成了一种与晶态和非晶态均不相同的新型结构，由此产生了许多独特的性能．本文综述了纳米晶材料的研究动态、介绍了纳米晶材料的制备、结构表征和性能研究的进展及纳米晶材料的发展动向。     

多元Gauss－Weierstrass算子的L_p－逼近

本文借助于Ｋ－度函和光滑模的等价关系，给出了多元Ｇａｕｓｓ－Ｗｅｉｅｒｓｔｒｓｓ算子的Ｌ－逼近的特征定理．     

主链改性聚醚聚氨酯电解质的合成与表征

用以氧亚甲基连接的聚氧乙烯([OCH_2(OCH_2CH_2)_9]_n,简称OM—PEO)与甲苯二异氰酸酯(简称TDI)反应,得到一种新的线型聚醚聚氨酯(简称OM—PEO—PU),产物分子量大于10~5,因而有望在不破坏OM—PEO优良导电率的前提下提高力学性能。     

Influence of electronic properties of Na2O/CaO catalysts on their catalytic characteristics for the oxidative coupling of methane

For Na₂O/CaO catalysts of different sodium content the adsorption of oxygen and their electrical properties were studied by transient experiments and measurements of contact potential differences (CPD) as well as electrical conductivity. CPD results show a change of the mechanism of oxygen activation with increasing sodium concentration due to changing the type of ionic conductivity from cationic to anionic. Anion vacancies are formed by incorporation of sodium into the CaO lattice. As CPDs show, the cation conductivity promotes an accumulation of oxygen species on the catalyst surface resulting in a decrease of C₂ product selectivity for the catalyzed oxidative coupling of methane. The anion conductivity favors a dissociation of molecular adsorbed oxygen and a subsequent incorporation into the oxide lattice, hereby, decreasing its concentration on the catalyst surface which favors in term selective formation of ethane and ethylene. This revised version was published online in July 2006 with corrections to the Cover Date.     

Discrete Events in Power Systems

The relevance of Discrete Event System theory (whether synthetic or analytic) to power system analysis and control is not clear. However, based on several characterizations of the domain of discrete systems set forth in the January 1989 Special Issue of the IEEE Proceedings, on Dynamics of discrete event systems (Ho, 1989), we attempt to delineate several power system control problems that may be amenable to analysis by DEDS methodologies. While the author is not qualified to judge whether the latter can speak to any of the examples, it may be relevant that in all cases the problems are non-trivial and in need of further contributions toward improved solutions, especially in view of the ongoing radical restructuring of the industry. The continuous process that is instantiated in the functioning of a power system is observed via three more or less diverse variables. Two of these, the scaler system frequency and the vector system voltage profile, are in principle mensurable physical phenomena; the third, system security, is a quality represented by a set membership conditioned on an inferred relationship between the two physical system variables and future realizations of one or more classes of autonomous stochastic phenomena. (These latter may be internal or external to the physical system, such as, e.g., respectively, equipment failure mechanisms and weather events.)     

The roles and electrochemical characterizations of activated carbon in zinc air battery cathodes

We prepared cathodes with various types of activated carbon and measured the cathodes’ electrochemical performance according to the kind of activated carbon. Activated carbon supplies airflow channels and reaction sites in the cathode of zinc air batteries. When we use activated carbon with a high specific surface area as the cathode's catalyst substrate, we expect high electrochemical performance because this type of carbon provides more air flow channels and reaction sites.We focused on investigating the relationship between the cathode's pore structure and its electrochemical characterizations. We also studied the effects of the various activated carbon materials on the zinc air batteries’ performance. Increasing the macropores or mesopores in the activated carbon resulted in achieving more power from the battery.     

椅子式基坑围护结构的应用

根据新建工程周边场地较小,邻近有建筑物的现状,地下室基坑难以用常规的围护结构,介绍了椅子式水泥搅拌桩墙围护结构方案,在有限宽度内,以高低桩结合满足其抗倾覆、抗滑移及整体稳定性要求成功的实例.     

深基坑内大直径反循环钻孔扩底桩设计与施工

深圳市广业大厦反循环钻孔扩底桩长20～35m，在深基坑内施工难度很大。为避免塌孔和确保质量，采取了提高水头，改善泥浆性能和超声波检测等手段。该法对地层适应能力强，钻孔直径，孔深可选范围大，振动小，噪声低，工期短，经检验各项指标均满足要求。     

Characterization of Structure and Transport in Porous Media by Pulsed Field Gradient (PFG) NMR Technique. Part I: Master Curve and Characteristic Inner Length

Systematic experimental studies focusing on the practical application of observation time dependent pulsed‐field‐gradient (PFG) NMR were performed. The objective was to provide engineering scientists with a reliable experimental tool for characterizing the structure and transport in fluid‐filled porous media. Observation time dependent self‐diffusion in glass bead packs as model systems was investigated, where the diffusing species (molecules of the solvent or dissolved particles) served as probes for the confining geometry in the porous medium. First, the basic question whether the obtainable structure information is independent of the actual mobility of the diffusing probe particles was examined experimentally. It could be demonstrated that plotting the normalized time‐dependent diffusion coefficient D(t)/D₀ versus the actual migration length l_D(t) during a given observation time t indeed yields a characteristic “master curve” that is independent of the mobility of the diffusing species, thus reflecting, as desired for a reliable method, solely the effects of the confining geometry of the porous system of interest. It was further shown that from the master curve a new quantity, i.e., a “characteristic inner length” or “correlation length” ξ_D can be derived that corresponds to a path length in the porous medium, after which particles in the pore fluid experience an averaged restricting geometry and diffuse with an effective diffusion coefficient D_eff. It turned out that ξ_D is surprisingly short, that is, in the order of the bead radius. Moreover, it was demonstrated that normalization of this migration length with the bead radius yields a common master curve for all monodisperse bead packs used and thus, it is obviously possible to derive and record master curves for different kinds of packs, beds or other porous media as references that can be used to characterize or certify the kind of the porous matrix of interest.