Interface characteristics and mechanical properties of carbon fibre reinforced copper composites

Interface characteristics of carbon fibre reinforced copper matrix composites materials with various interface states and their effect on the flexural strength of composites have been studied. Interfacial states are mechanical bonding, dissolution bonding and reaction bonding. To a certain extent, raising the interfacial strength enables an increase in the flexural strength due to prevention of carbon fibre being pulled out under low stress during fracture process of composites. Raising the interfacial bondage strength, causes the brittleness of composites to increase; the fracture surface of composites is converted from a fibre pull-out model to a fibre even model. While strengthening the interface bondage, the extent of chemical reaction and dissolution at the interface must be controlled to avoid degrading the carbon fibre.     

磁场对泡沫钻井液电导率的影响研究

磁处理技术是利用磁场对非铁磁性流体作用．使被作用物的性质产生某些期望的变化，从而改善生产效果和使用效益。磁处理对常规钻井液流变性能的影响研究结果表明，磁化能明显改善钻井液性能。通过研究磁化后泡沫钻井液的性质．测定与控制钻井液的电导率，以便从电测曲线上取得更好的地层特性评价。泡沫钻井液的电导率与密度基本呈线性关系，电导率随密度的升高而变大；磁处理后泡沫钻井液的性质发生明显改变．泡沫钻井液的电导率有不同程度的下降，在磁场强度为100mT、蜂数为2的磁场条件下泡沫钻井液的电导率变化率降低最大，电导率平均下降16％左右。     

可持续发展战略指导下的轨道交通规划与评价

提出了轨道交通规划与评价在实施可持续发展战略过程中需要研究的问题，研究重点是轨道交通规划与评价方法体系和环境对策，研究了轨道交通规划目标的变化、轨道交通规划优化决策理论与方法、轨道交通规划中的环境影响评价、城市轨道交通网络的合理规划、城际轨道交通——客运专线/高速铁路线路基本走向的规划、轨道交通规划可持续发展的评价指标体系概念框架、轨道交通系统可持续发展的能力建设问题等，并通过实例验证了所建立的理论方法体系和模型体系；不仅进行了有关理论和方法的探讨，而且以面向实际应用为目标，开发了相应的软件系统，为轨道交     

Object-oriented DBMS requirements

The requirements on an object-oriented DBMS for management of information in a large, complex enterprise are presented. These requirements aid in the achievement of an environment characterized by data sharing, open architectures, application and data portability, and assurance of data integrity. They were defined from the point of view of a user of the DBMS; therefore they describe the expected functionality of the DBMS and do not specify the method of implementation to achieve this functionality. They encompass requirements on the data model, query and data manipulation languages, the system architecure, interfaces to the system, change management, and transaction management.     

Specification methods for material-handling control algorithms in flexible manufacturing systems

Good methods are needed to specify, test, and debug material-handling control logic. This article surveys a number of representative methods for defining and describing control algorithms for programmable material-handling equipment used in flexible manufacturing systems. The methods are evaluated with regard to their suitability for communication between people and as bases for interfaces to automatic program generators. It is concluded that no single method is entirely satisfactory. Three methods (position diagrams, function block diagrams, and operation networks) have potential to be combined into an effective hybrid approach that minimizes the need for the user to switch between various conceptual models.     

The relativistic charged particles identification method based on the goodness-of-fit ωn-criterion

The statistical method of identification of relativistic charged particles by measurements of ionization losses or time-of-flights simultaneously in some detectors of an experimental plant on the basis of the new goodness-of-fit ω_n³-criterion is considered. The method proposed has been used for the secondary particles identification from the high energy -particles fragmentation on target nuclei. The efficiency of the method is excellently illustrated by reliable separation of events (rare events as well), connected with the appearence of 1- and 2-charged particles. The comparison of the ω_n³-method with the traditional methods and with the method based on the ω_n²-criterion shows that the new method outperforms the ω_n²-method and most of the traditional ones in efficiency, but compares unfavourably with the likelihood method in power, however, the former has a number of advantages as compared with the latter.     

Slow eroding biodegradable multiblock poloxamer copolymers

Biodegradable multiblock poloxamers (BMPs) with gel duration of 8 h to several weeks were prepared by varying their molecular weights from 4000 to 40 000 g mol^?1. The molecular weight of the BMP was controlled by changing the poloxamer to coupling agent ratio. Assuming a micelle packing model of the BMP gel, as in the case of a poloxamer gel, the micelle properties and critical gel concentration of BMPs were investigated on the basis of the scaling concept. The findings suggest that the control of molecular weight by hydrolyzable groups can be a facile approach to optimize the gel properties for biomedical applications. Copyright © 2005 Society of Chemical Industry     

Implementing total quality management at the U.S. Department of Defense

This paper examines Total Quality Management (TQM) as defined by Dr. W. Edwards Deming including Deming's fourteen points and explains how the United States' Department of Defense (DOD) defines TQM and why TQM is necessary. It also covers how the DOD is planning on implementing TQM and the policy that has been established as guidance in the implementation process.     

A micromechanical model for cleavage-crack reinitiation

A crack-tip screening analysis of cleavage fracture of steel is developed. The analysis incorporates evidence that reinitiation of an arrested cleavage crack requires less stress intensity than cleavage initiation from a fatigue precrack. Fractographic evidence as well as metallographic sectioning of arrested cracks have previously shown that the mechanism of rapid crack propagation by cleavage is affected strongly by partial crack-plane deflection which leaves unbroken ligaments in its wake. The tearing of these ligaments by dimple rupture is the dominant energy-absorbing mechanism. Earlier etch-pit experiments using an Fe-Si alloy showed that the crack-tip stress intensity based on plastic zone size is extremely low. These observations are incorporated into a model in which cleavage crack reinitiation is analyzed using a sharp crack that is shielded by a distribution of pinching forces along its faces. During reloading of the arrested crack, the ligaments restrict crack-tip blunting, leading to higher local stresses. As a result, lower stress intensities are needed for reinitiation than for initiation from a fatigue precrack.