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61.
Two studies examined the effects of cross-group friendships on heterosexuals' attitudes toward gay men. In Study 1, the authors tested the effects of cross-group friendships with gay men on out-group attitudes, meta-attitudinal strength, and attitude accessibility. The authors simultaneously explored mediational effects of intergroup anxiety. Path analysis showed that cross-group friendships were associated with meta-attitudinally stronger and more accessible out-group attitudes, and the effects on all 3 criterion variables were mediated by intergroup anxiety. In Study 2, the authors sought to replicate the basic results of Study 1, while additionally exploring mediational effects of closeness of cross-group friendship and moderational effects of perceived group typicality. Structural equation modeling showed that cross-group friendships were associated with meta-attitudinally stronger and more accessible out-group attitudes; friendships had indirect effects on all 3 criterion variables, via closeness of friendship and intergroup anxiety. Closeness of friendship only predicted lower intergroup anxiety, however, when the out-group friend was perceived as highly typical. The authors emphasize the importance of considering the nature of out-group attitudes more completely when evaluating the effectiveness of intergroup contact in reducing prejudice. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
62.
The forces, chip thickness, and natural tool–chip contact length in machining with a double-rake-angled tool are predicted in Part II of the present study. It is revealed that in comparison with a single-rake-angled tool, a double-rake-angled tool increases the forces, especially the thrust force. However, the increase in chip thickness and tool–chip contact length is not significant under the input conditions specified in the present study. The effect of seven input variables of the proposed model is quantitatively investigated. The predicted variations of forces, chip thickness, and natural tool–chip contact length are in good agreement with theoretical and experimental results obtained by other researchers. The interrelationships among the resultant force, the chip thickness, and the natural tool–chip contact length are established, which provides a new and promising method to estimate the tool–chip contact length by employing the resultant force. It is demonstrated that the model can also be extended to study the problem of machining with a groove-type chip breaker tool. 相似文献
63.
R. Gnanamoorthy N. Rajiv K. Gopinath Y. Miyahsita Y. Mutoh 《Journal of Failure Analysis and Prevention》2002,2(4):71-75
Powder-metal-processed bearings and gears are finding increasing application because of their economical and technical advantages.
The residual pores from the sintering operatives act as lubricant pockets and dampen sound and vibration. However, porosity
also decreases the mechanical strength and reduces the life of components fabricated by powder processing relative to similar
wrought components. The rolling contact fatigue behavior of sintered and heat treated steel rollers was investigated using
a fatigue test machine designed and fabricated for that purpose. The powder-metal-processed and the wrought steel rollers
that were tested had similar composition and hardness and were mated against wrought steel rollers of high hardness. The contact
stress versus number of cycles to failure data showed that the wrought steel had a very high endurance limit under rolling
contact fatigue compared to the sintered steels investigated. Rolling contact fatigue behavior was found to depend on the
porosity present in the material. Large surface peeling failures and pitting type fatigue failures were observed in the sintered
and hardened steels, while only pitting type failures were observed in the wrought steels 相似文献
64.
65.
The axisymmetric Laplace equation is solved numerically to extract contact-angle data for a flat liquid/vapor interface contacting a submerged hemispherical solid. The liquid/vapor interface is treated as a membrane, with a membrane tension equal to the surface energy of the liquid. By measuring the vertical displacement of the membrane and the projected contact area the membrane makes with the hemisphere, the contact angle and correspondingly the driving force for motion of the contact line can be measured. We show that characteristic receding and advancing contact angles can be obtained by measuring the contact radii formed upon initial contact between the interface and hemisphere and final contact just prior to detachment of the interface, respectively. Use of the technique is illustrated with a model experiment involving the contact of an air/water interface with a poly(methyl methacrylate) surface. 相似文献
66.
M. Muhr S. Pack S. Jaufer H. Lugschitz 《e & i Elektrotechnik und Informationstechnik》2006,123(12):537-543
New developments in diagnostic tools and systems are necessary for a reliable and economic evaluation of the condition of
equipment in power systems. In a research project a tool for the condition of contacts of centre break disconnector, which
is used under normal operation by the aid of a thermography measurement system, has been developed. In this paper, an overview
about the laboratory investigation of the temperature load behaviour and the environmental influence on-site for new and aged
disconnector contacts are given. A condition evaluation tool for contacts, which was the aim of the project, has been created.
The basic method for the evaluation is presented, and also two additional easements for a fast identification of suspect contacts
are presented. With this evaluation tool and the usage of a thermography based measuring system, a condition based maintenance
strategy can be applied, whereby an early detection of damages is possible and so power quality and reliability increase.
相似文献
67.
The grafting of acrylic acid onto electron beam‐irradiated polypropylene was carried out using preirradiation method. The stability of peroxy radicals was investigated by electron spin resonance. It was found that the decay of peroxy radicals is much faster at 70°C than at 40°C and ambient temperature. The grafting has been observed to be strongly dependent on the monomer dilution in the reaction medium. The grafting was ascertained by attenuated total reflectance (ATR). The distribution of grafts across the samples was monitored by infrared microscopy. It was found that the graft management is considerably influenced by composition of the grafting medium. The grafting involving pure monomer leads to the surface enrichment with the polyacrylic acid chains. The samples grafted in pure monomer led to much lower contact angles as compared to the diluted monomer solution. The swelling of the grafted samples also showed a trend that was governed by the graft management. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 546–553, 2006 相似文献
68.
硬粒子对聚合物材料表面的冲击摩擦研究 总被引:3,自引:3,他引:0
冲击摩擦为接触面切向与法向冲量之比。用聚合物材料试件与弹簧钢片组成振动测试系统 ,硬粒子以一定入射角冲击试件水平面引起系统振动 ,接触冲量通过振幅反映出来 ,记录初始振幅值而计算出一个冲击过程的冲击摩擦因数。结果表明 ,当入射角α在 2 5°-60°变化时 ,冲击摩擦因数f从 0 .5降至 0 .2左右。文章同时分析讨论了摩擦对聚合物表面接触强度的影响。 相似文献
69.
共聚物水凝胶的合成及其溶胀性能研究 总被引:3,自引:1,他引:2
以过氧化二苯甲酰(BPO)为引发剂,合成了N-乙烯基吡咯烷酮(NVP)-甲基丙烯酸肛羟乙酯(HEMA)-甲基丙烯酸丁酯(BMA)共聚物水凝胶,可作为软性角膜接触镜材料。探讨了不同比例的NVP、HEMA、BMA对材料溶胀性能的影响。 相似文献
70.
This paper presents some results from a totally new and powerful fusion between automated, digital photoelastic techniques and mathematical analysis of a crack experiencing closure. In essence, real-time photoelastic stress field data is acquired and fitted to a Muskhelishvili complex potential model of a loaded crack experiencing closure. The fit entails optimisation of multiple variables via a memetic algorithm, which combines a genetic algorithm and a local search. From observations made in this work, it is proposed that the plastic enclave around a crack tip will shield the crack from the full influence of the applied stress field. Furthermore, the effects of this ‘back stress’ are overcome by the applied tensile load in a way that, often, cannot be readily correlated with crack contact length, wake contact force, or with compliance. 相似文献