Stress Analysis of the Double-Torsion Specimen

The double-torsion specimen was analyzed with a 3-dimensional elastic finite-element stress analysis. A crack-front configuration where the stress intensity is constant over ≅ 1/2 of the specimen thickness was determined. That value of the stress intensity is nearly equal to the "strength-of-materials" value. The stress intensity is nearly constant for crack lengths > 0.55 × specimen width ( W ) and ligament lengths > 0.65W.     

Kinetic and Thermodynamic Considerations Regarding Interphase Formation in Thermosetting Composite Systems

Thermodynamic and kinetic treatments are employed to analyze the role of preferential adsorption and diffusion in the formation of interphase regions in thermosetting composities. The thermodynamic analyses show that a driving force exists for the preferential adsorption of amines onto carbon fiber surfaces in amine-epoxy systems. Scaling analyses, based on kinetic considerations, lead to the identification of reaction-diffusion time regimes that control interphase formation in sized and unsized fiber systems. These considerations provide guidelines for the selection of material formulations and processing conditions that may be used to tailor behavior of the interphase region in thermosetting composites.     

Kinetic and Thermodynamic Considerations Regarding Interphase Formation in Thermosetting Composite Systems

Thermodynamic and kinetic treatments are employed to analyze the role of preferential adsorption and diffusion in the formation of interphase regions in thermosetting composities. The thermodynamic analyses show that a driving force exists for the preferential adsorption of amines onto carbon fiber surfaces in amine-epoxy systems. Scaling analyses, based on kinetic considerations, lead to the identification of reaction-diffusion time regimes that control interphase formation in sized and unsized fiber systems. These considerations provide guidelines for the selection of material formulations and processing conditions that may be used to tailor behavior of the interphase region in thermosetting composites.     

Practical Considerations in Kinetic Resolution Reactions

This review provides a critical analysis of catalytic kinetic resolution reactions from a practical perspective, asking the question of when, if ever, is kinetic resolution the best option for the synthesis of an optically active target. A series of crucial conditions are identified, and it is postulated that if all of them are met, then indeed kinetic resolution can be highly practical. A variety of catalytic kinetic resolution processes are evaluated in the context of these criteria, with particular emphasis on catalyst availability, substrate scope, availability of the racemic substrate and of alternative methods for accessing enantiopure substrate or product, and key experimental considerations. It is found that several catalytic systems have been developed that offer almost unbeatable methods for the preparation of useful chiral building blocks.     

Realistic Finite-Element Model for the Double-Torsion Loading Configuration

The analytical approach to the double-torsion, constant-displacement-configuration technique has forced a strong oversimplification of the specimen model, and, therefore, of the strain field in classical applications. For the present study, accurate three-dimensional finite-element analysis was performed on a realistic specimen; that is, one with finite thickness, a groove, and an initial notch. The influence on the strain-energy release rate of the specimen width and length, the fracture length, the presence and shape of the side groove, the presence of an initial notch, and the curved shape of the fracture front was estimated from this analysis. Significant deviations from the classical analytical solution were found. The present results should reduce the discrepancies found among measurements made in various laboratories and that traditionally have prevented the development of effectively applicable fracture models.     

关于中国能源形势的思考

分析了近年来中国能源消费增长的形势,指出我国能源消费将长期以煤为主,我国石油供应必须依靠国内和国外两种资源。     

关于高分子材料成型技术的相关思考

在经济发展、社会进步和人们生产、生活对有机物高分子物质材料应用越来越广泛的进程中,科研人员和生产企业不断提高科技创新、自主创新能力,在有机高分子材料物质成型技术的研究方面不断有新的突破。就高分子材料物质成型技术问题进行了研究探讨。     

Some Considerations of Nonideal Transformation-Zone Profile

The nonideal transformation-zone profile, in which the volume fraction of transformed particles decreases with the increase in the lateral distance from crack surfaces, is considered for the stress-induced phase transformation in ceramics containing zirconia. It is shown that one source of this nonideal transformation-zone profile can be the size distribution of the transforming particles/grains. Then, an equation for toughening due to the existence of such a nonideal transformationzone profile is derived. In calculating the toughness, it is shown that the uncertainty in determining the transformationzone size, which can occur by attempts to fit it to an ideal zone profile, can be avoided by using the present approach.     

关于中国能源战略的思考

分析了在能源问题上人类面临的主要挑战以及中国能源消费存在的主要问题和不足,深入剖析了构建中国能源安全保障体系的重要性,提出了关于中国能源战略的几点思考。     

对我国能源前景的一些思考

概略分析了我国能源形势，并与国际能源状况做若干对比，对我国GDP翻两番时的能源消费及生产的框架提出看法。     

中国水泥工业发展的思考

今年国家将以更加严厉的财政政策和货币政策进行宏观调控,在这种形势下,国家有关部委公布了《国家重点支持水泥工业结构调整大型企业(集团)名单》,这是促进水泥工业结构调整和落实水泥行业一系列     

构建和谐油区的思考

阐述了油田与员工、生态环境及地方之间和谐发展的关系,指出了油田可持续发展面临的问题,提出了油田可持续发展的对策。     

Kinetic Study of the Ozonation of Some Industrial Wastewaters

Kinetic studies of the ozonation of two wastewaters released by distillery and tomato processing plants have been carried out. Once it has been assumed that an irreversible gas-liquid reaction is developed between ozone and the matter present in the water, the film theory concept was applied to this system for kinetic determinations. The evolution of the organic and inorganic matter with ozonation time has been followed by the chemical oxygen demand. The procedure allows the determination of the rate coefficients of ozone with the wastewaters treated. According to the results obtained, ozone is consumed through fast reactions which take place near the water-gas interface during an initial period. This period is used to determine the rate coefficients. Then, at more advanced ozonation times, the reactions become slower and hence they take place in the bulk of the water, articularly for the case of tomato wastewaters. Values of the rate coefficient allow us to establish both the kinetic regime of absorption and to compare the reactivity of ozone with the wastewaters and single compounds.     

水平井地质导向管理思考

针对目前陆上水平井地质导向存在随钻测井资料项目少、资料品质差、组织结构不合理、服务价格低下等问题,提出了组建专门水平井技术服务公司实现导向、定向、测量、录井一体化,增加方位伽玛测井,制定措施提高随钻测井资料品质,开发远程地质导向决策系统,确定合理的服务价格等手段提高水平井地质导向水平,降低水平井导向风险的对策。     

Verification of the Double-Torsion Equation by Using Different Thickness Samples of a Machinable Glass-Ceramic

The double-torsion technique is commonly used to measure fracture toughness. A finite thickness of samples is used for the measurement; however, for samples of varying thickness, a correction factor is introduced in the double-torsion equation. This was verified by using machinable glass ceramic samples differing in thickness.     

对重组石油企业整合问题的几点思考

以中国石化西南地区油气勘探开发企业为例，论述了重组石油企业在进行战略整合、管理整合及队伍整合时的方法及建议。     

关于我国石油装备技术发展的思考

评述了二十多年来我国发展石油装备技术取得的成就,分析了未来世界石油装备技术发展趋势,以及我国石油装备技术发展面临的任务和挑战,提出了我国石油装备技术实现跨越式发展应采取的措施。     

关于界面物理化学讲解的几个实例

在物理化学教学中注重扩展课堂知识“外延”、拓宽学生的知识视野,培养较高层次学生理论联系实际的能力;注重“内涵”的知识联系,强化基础知识框架中的多通路知识网络,提高学生解决问题的能力。本文以界面物理化学教学为例对此进行探讨。