纳米CaCO3/PVC增塑糊体系触变性能研究

研究了纳米CaCO3/PVC增塑糊体系的触变性能,并在分析纳米CaCO3/PVC增塑糊体系中作用力、增塑糊中物CaCO3粒子分布状态的基础上建立了纳米CaCO3/PVC增塑糊体系的微观结构模型,依据该模型提出了纳米物CaCO3/PVC增塑糊体系的触变性行为机理。结果表明,从触变性能出发,纳米CaCO3的填充量存在一个最佳范围;随着剪切力的增大,CaCO3粒子间拟网络结构的平衡状态逐渐被破坏,体系的微观结构形态发生变化,粒子间的距离被拉开,颗粒间的作用力由排斥转变为吸引。在外部剪切力消除后,布朗运动和团聚体颗粒间的吸引力使得体系又恢复到静止状态的拟网络结构,但恢复过程需要一定时间,从而使体系体现出触变性行为。     

The role of research for the social shaping of new technologies: Designing a research strategy

With increasing flexibility of technology and a shift towards competence being the core of competitive edge in worklife, the need for new organizational concepts or models which givejoint optimization across human and technological dimensions has been acknowledged in leading, innovative enterprises. National crossdisciplinary research based productivity programmes are appearing in several countries. Due to internationalization and the general shortcomings of bureaucratic organizational forms, regional networks of enterprises in cooperation with public R&D institutions seem to provide answers to needs of regions to remain competitive. The paper discusses the possible role of social science in a multilevel, participative strategy for developing new, democratic and productive organizational forms in worklife. Aspects of national productivity programmes in Scandinavia, Germany and Australia are discussed in connection with the situation in Italy as analyzed through some recent research projects.     

Mechanical stresses on products during air cargo transportation

A field study was conducted on board a Boeing 747 Combi (freight and passenger) aircraft on the route Stockholm (Arlanda) via Oslo (Gardermoen) to New York (John F. Kennedy Airport) and return to Stockholm (Arlanda). Shock and vibration, acting on the cargo, during air transportation were measured and analysed. The study encompassed all phases of the flight, including taxiing, climb, cruise during both calm and turbulent conditions, descent and approach, landing including touchdown and taxiing to apron. The field data were analysed by conventional frequency analysis and modelling techniques. In order to generalize the results, flight recorder data from the field trial and from other flights are included. Guide-lines for the development of realistic, simulation test programs for product and package design are included.     

Effect of polypropylene as the backbone of MIM feedstock on the micro-structural phase constituents,mechanical and rheological properties of 4605 low alloy steel compacts

ABSTRACT

In this study, the effect of polypropylene (PP) as the backbone polymer of Metal injection moulding (MIM) feedstock has been investigated on the micro-structural phase constituents, mechanical and rheological properties of 4605 low alloy steel compacts. For this purpose three binders systems consisting of paraffin wax (PW), stearic acid (SA) and carnauba wax (CW) having different contents of PP (20, 24 and 28 mass %) were compounded. The sintered samples were then tested for mechanical (tensile and hardness), micro-structural (X-ray diffraction (XRD) and scanning electron microscope (SEM)), density and rheological (viscosity) properties. The results show that an increase in the PP percentage results into the improvement of mechanical and physical properties while decreasing the rheological properties. From the microstructure point of view it was observed that the amount of PP, is directly related to the residual carbon content of the sample which affects the grain size, total porosity and phase constituents.     

Influence of sharp microstructural gradients on the fatigue crack growth resistance of α+β and near-α titanium alloys

The present study focuses on the effect of microstructural gradients on the fatigue crack growth resistance of Ti‐6Al‐4V and Ti‐6242 titanium alloys. Sharp microstructural gradients from fine‐grained bimodal to coarse‐grained lamellar microstructures were obtained by heat treating only a portion of fine‐grained plates in the β single‐phase field using a high‐frequency induction coil. For fatigue crack growth from a bimodal into a lamellar microstructure, it was found that the initial crack extension past the microstructural transition within the lamellar microstructure shows the same crack growth resistance as the reference bimodal microstructure. Similarly, for fatigue crack growth from a lamellar into a bimodal microstructure, the initial crack extension past the microstructural transition within the bimodal microstructure shows same crack growth resistance as the reference lamellar microstructure. Based on detailed crack front profile investigations using optical light and scanning electron microscopy as well as heat tinting procedures, these findings can be mainly attributed to the effect of the crack front geometry.     

V-5Cr-5Ti合金的内耗特征研究

研究了不同处理状态下V-5Cr-5Ti合金的内耗特征,并结合微观缺陷的作用机制对内耗峰进行分析。利用倒扭摆仪和多功能内耗测试仪进行内耗测试,采用X射线衍射(XRD)分析相结构,扫描电镜(SEM)观察微观组织。研究结果表明,V-5Cr-5Ti合金制备过程中无法完全消除C、O、N等杂质元素,这些元素会以间隙原子或沉淀相颗粒形式存在,进而影响合金的微观组织缺陷。在不同的处理状态下,杂质元素的不同存在形式会使合金的内耗会产生不同的变化特征。根据内耗机制,所有的内耗峰均可以由应力作用下微观缺陷的运动来揭示,比如点缺陷、位错、晶界等。     

Leakage Control in a Universally Metered Distribution System: Pinetown Water's Experience

As a result of water losses reaching a high point of 16% in 1973, combined with a relatively high and increasing retail tariff, the Pinetown Regional Water Services Corporation embarked upon a programme to reduce losses to an acceptable level of about 10%. The programme involved: (i) the establishment of district metering throughout the distribution system; (ii) the replacement of certain retail meters; and (iii) the metering of new fire connections (other than those serving sprinkler installations). Further steps were taken to improve the situation and included: (a) the monitoring of minimum night flows, (b) regular sounding of distribution mains; (c) the establishment of a full-time waste detection gang; and (d) with improved control valves becoming available, more effective pressure control of the system. The Corporation's computer was called upon to determine: (i) the monthly losses from each of the hundred or so districts; (ii) the life history, in graphical form, of retail meters under review; and (iii) a record of expenditure on leakage control. The paper describes the development of the methods used in leakage control, costing less than half a cent per cubic metre of water purchased, and outlines the practical experience gained in reducing losses from 16% to less than 5% over a period of 14 years.     

贯通测量方案的选择与误差预计

编制贯通测量设计书的主要任务是选择合理的测量方案和测量方法,以保证巷道正确贯通。要选择贯通测量方案及误差预计的一般方法,了解情况,收集资料,初步确定贯通测量方案,选择合适的测量方法进行贯通误差预计,贯通测量方案和测量方法的最终确定。     

Training graduate students to be clinical supervisors: A survey of Canadian professional psychology programmes.

Recognising the need for training in clinical supervision, the Canadian Psychological Association (CPA) requires that accredited professional psychology programmes offer graduate students training in supervision. To fill a gap in the existing supervision literature, we surveyed training directors (or designates) of CPA accredited clinical and counselling programmes to understand how this training standard is currently being met in the area of clinical supervision. Responses were obtained from 20 of 28 programmes (71.4% response rate). Approximately 50% of respondents indicated that their programmes required some coursework related to clinical supervision, with wide variability, however, in the number of hours of coursework provided to students (range 3 to 39). Most courses included lectures and group discussion, but also often provided students with practical experience in clinical supervision provision. Only 25% of programmes required a practicum in which students gained experience in clinically supervising other students, although an additional 40% of programmes offered an elective practicum in which students gained some training in clinical supervision. Most programmes (~71%) identified strategies for improving training in clinical supervision (e.g., improving course work, requiring practical experience), but also identified challenges to offering clinical supervision training (e.g., availability of skilled supervisors, insufficient time to devote to supervision, student competency). Based on the findings, we offer some recommendations for how training in clinical supervision could be improved in Canadian professional psychology programmes as well as describe some important directions for future research in this area. (PsycINFO Database Record (c) 2010 APA, all rights reserved)