A fractal model of reinforcement of elastoplastic nanocomposites

Within the framework of fractal analysis and percolation theory, an alternative model of reinforcement of filled polymers is offered. Practically, this model can be used only to describe the reinforcement of nanocomposites, because, according to the treatment considered, a pronounced reinforcement can be reached only at ratios of filler particle diameter to the statistical segment length of about 10 and less. A theoretical calculation showed a good qualitative and quantitative agreement with experiments. The type of reinforcement mechanism of composites is determined by the type of the space (fractal or Euclidean) in which the structure of the polymeric matrix is formed. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 6, pp. 797–802, November–Decem ber, 2006.     

Mossbauer investigations of corrosion environment influence on Fe valence states in oxide films of zirconium alloys

Mössbauer investigations about iron atom redistribution in oxide films of zirconium alloys subjected to corrosion at 500°C in pure oxygen and water pair have been analysed. The alloys were also subjected to autoclave conditions at a pressure of 10.0 MPa and autoclave conditions at 350°C and at a pressure of 16.8 MPa, using distilled water and water with additives of lithium and fluorine. It is shown that, depending on the corrosion environment, various compounds of iron, such as α-Fe₂O₃, Fe₃O₄, and FeO, as solid solutions of iron in ZrO₂ are formed in oxide films.     

Action learning versus strategy learning

This article seeks to ascertain whether the strategy‐learning model of Hanaki, Sethi, Erev, and Peterhansl (2003) better accounts for observed behavior than do the various action‐learning models. It does so by measuring the goodness‐of‐fit of the models' predictions against published experimental results for such games as Coordination, Prisoner's Dilemma, and Chicken. The fit is measured via the mean squared deviation (MSD) between the observed behavior and the one predicted by the model. The results show that, for Chicken, the strategy‐learning model fits the observed data much better than do the action‐learning models. The best action‐learning model, on the other hand, fits the observed data well in Coordination. Overall, the strength of the strategy‐learning model is best shown in games where alternations between the two stage‐game Nash equilibria are often observed in the laboratory experiments. © 2004 Wiley Periodicals, Inc. Complexity 9: 41–50, 2004     

Application of a Near-Optimal Reinforcement Learning Controller to a Robotics Problem in Manufacturing: A Hybrid Approach

Optimization theory provides a framework for determining the best decisions or actions with respect to some mathematical model of a process. This paper focuses on learning to act in a near-optimal manner through reinforcement learning for problems that either have no model or the model is too complex. One approach to solving this class of problems is via approximate dynamic programming. The application of these methods are established primarily for the case of discrete state and action spaces. In this paper we develop efficient methods of learning which act in complex systems with continuous state and action spaces. Monte-Carlo approaches are employed to estimate function values in an iterative, incremental procedure. Derivative-free line search methods are used to obtain a near-optimal action in the continuous action space for a discrete subset of the state space. This near-optimal control policy is then extended to the entire continuous state space via a fuzzy additive model. To compensate for approximation errors, a modified procedure for perturbing the generated control policy is developed. Convergence results under moderate assumptions and stopping criteria are established.     

The origin of the formation of cavities in galvanized coatings

The role of water‐soluble corrosion products on galvanized wires was examined. The samples used were industrial hot‐dip galvanized wires, which were exposed to the open air under all weather conditions for a relatively short time (6 and 12 months), in an urban environment close to the sea. The samples were studied by different methods, i.e. scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and optical microscopy (OM). Several phases were detected because of the galvanization procedure and the steel substrate. Furthermore, phases which were formed as a result of the reaction of zinc with the atmosphere were also detected. These were oxides like ZnO, carbonates like ZnCO₃ and hydrated Zn and Fe sulfates. Their presence influences the corrosion resistance of the wires, which finally, strongly depends on the solubility of the wires in water. The SO₄^2? compounds especially are very soluble and consequently are easily removed from the coating surface, leading to its degradation by the formation of cavities. In any case, their presence, even after a short period of exposure, implies that the coating is highly affected by the atmosphere of the modern city. Copyright © 2006 John Wiley & Sons, Ltd.     

Surface-enhanced Raman scattering study of polymer on metals. III. Chemisorbed polybenzimidazole and its corrosion-inhibiting properties at high temperature

Chemisorption of polybenzimidazole on silver and copper etched with nitric acid has been observed by surface-enhanced Raman scattering (SERS). The polymer is found to react chemically with silver, forming a complexed film on the surface. The SERS spectra show that polybenzimidazole film inhibits oxidation of the metal at high temperature, unlike chemisorbed benzimidazole, benzotriazole, and poly(4-vinyl pyridine). © 1992 John Wiley & Sons, Inc.     

Hydrogel‐like elastic membrane consisting of semi‐interpenetrating polymer networks based on a phosphorylcholine polymer and a segmented polyurethane

To obtain a hydrogel‐like elastic membrane, we prepared semi‐interpenetrating polymer networks (IPNs) by the radical polymerization of methacrylates such as 2‐methacryloyloxyethyl phosphorylcholine (MPC), 2‐hydroxyethylmethacrylate, and triethyleneglycol dimethacrylate diffused into segmented polyurethane (SPU) membranes swollen with a monomer mixture. The values of Young's modulus for the hydrated semi‐IPN membranes were less than that for an SPU membrane because of higher hydration, but they were much higher than that for a hydrated MPC polymer gel (non‐SPU). According to a thermal analysis, the MPC polymer influenced the segment association of SPU. The diffusion coefficient of 8‐anilino‐1‐naphthalenesulfonic acid sodium salt from the semi‐IPN membrane could be controlled with different MPC unit concentrations in the membrane, and it was about 7 × 10² times higher than that of the SPU membrane. Fibroblast cell adhesion on the semi‐IPN membrane was effectively reduced by the MPC units. We concluded that semi‐IPNs composed of the MPC polymer and SPU may be novel polymer materials possessing attractive mechanical, diffusive‐release, and nonbiofouling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 68–75, 2003     

稀土及杂质元素对ZA27合金晶间腐蚀的影响

为了从本质上了解杂质与稀土元素对锌铝合金晶间腐蚀的影响 ,探索抑制合金晶间腐蚀的有效途径 ,依据晶界的大角度重位点阵理论编制出相应计算机软件 ,建立含稀土、杂质及 η相颗粒的α相大角度晶界原子集团模型 ,采用递归法计算了α相晶界间的电荷转移 ,由此讨论了杂质 (Pb、Sn、Cd)及稀土元素 (La、Y)对Zn、Al电极电位的影响 .结果表明 ,杂质Pb、Sn、Cd增大原子间的电荷转移量 ,提高Zn、Al电极电位差 ,加速合金的腐蚀 ,稀土元素减小原子间的电荷转移量 ,降低Zn、Al电极电位差 ,具有抑制晶间腐蚀的作用 .     

丹麦生物质发电的现状和研究发展趋势

丹麦是世界上利用秸秆生物质燃烧发电技术开发、运行最好的国家，其经验值得中国借鉴。根据作者在丹麦对生物质燃烧发电的研究经历，系统地介绍了丹麦在秸秆生物质发电的经验、遇到的问题及相应的研究和今后的发展方向。     

化学复合镀Ni-P-PTFE镀层的组成分析

近年来化学复合镀技术在工业中应用日益广泛 ,本文运用ＳＥＭ、ＡＥＳ和ＸＰＳ等手段对用化学复合镀制得的Ｎｉ Ｐ ＰＴＦＥ镀层的结构和组分进行了分析 ,并就其耐腐蚀性能与前期得到的Ｎｉ Ｓｎ Ｐ[1 ] 、Ｃｕ Ｓｎ Ｐ[2 ] 、Ｎｉ Ｐ ＣｅＯ2 [3] 、Ｎｉ Ｐ ＳｉＯ2 [4] 镀层进行了比较 ,结果表明 :含量一定的ＰＴＦＥ(聚四氟乙烯 )的共存增强镀层的耐腐蚀性及镀层表面的润滑性。1　实验部分1 1　仪器日产Ｄ/ＭＡＸⅢＡ型Ｘ 射线衍射仪 ,铜靶 ,管压 2 5ｋＶ ,电流 1 0ｍＡ。国产ＪＪＣ 1型润滑湿角测量仪。美国ＰＥＲＫＩＮ ＥＬＭＥＲＰ…