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991.
Image capture and quantification has proven useful in a variety of scientific applications, for example, biology, medicine, geology, meteorology and forensics. The objective of this research was to utilize this technology to quantify clinical- and consumer-perceivable changes in facial attributes. A panel of expert assessors was trained, and, in a large consumer study, consumer facial attributes were identified and grading scales for each attribute were established. These experts then rated over 240 subjects on a total of 19 different facial attributes. Based on methodology developed by Perrett et al., facial averages or prototypes were computed from panelists rated high or low for each attribute. Prototypes were developed in a 3 step process: 1) selection of 224 predefined feature points; 2) calculation of average face shape; and 3) 'morphing' individual faces into that shape and blending the images together. Naive assessors could readily appreciate the differences in facial appearance of the prototypes. In addition, expert graders were able to identify the general class of attribute affected. This method provides a powerful tool for assessing the effects of skin care technologies.  相似文献   
992.
Off-flavor due to lipid degradation is an important factor in the shelf life of peanut products. The use of recently developed peanuts with high-oleic acid/linoleic acid (O/L) ratio has the potential to significantly extend the shelf life of roasted peanuts. To determine the full potential for shelf-life improvement of oil-roasted high-O/L peanuts, a study was conducted to examine the effects of roasting high-O/L peanuts (O/L=30) in high-O/L (O/L=23.2) or conventional (O/L=1.5) peanut oil. Peanuts were roasted at 177°C to Hunter L values of 49±1. Roasted peanuts were stored at 30°C for 20 wk. Samples were taken at regular intervals to determine PV, oxidative stability index (OSI), moisture content, and water activity. The O/L ratio of high-O/L roasted peanuts was 27.9 vs. 13.6 for the conventional oil-roasted peanuts. After 20 wk of storage, PV of conventional oil-roasted peanuts was 10.8 compared to 5.3 for the high-O/L-roasted peanuts. OSI values were 88.5 and 52.4 immediately after roasting for the high-O/L-roasted vs. conventional oil-roasted peanuts. OSI for both decreased, but differences remained similar throughout the storage period. Shelf life of high-O/L peanuts decreased when roasted in conventional O/L-peanut oil vs. high-O/L peanut oil.  相似文献   
993.
The effect of two slaughter methods (immersion in ice-water slurry and electrical stunning followed by ice slurry asphyxiation) on chemical and microbiological parameters of grass carp (Ctenopharyngodon idella) stored in ice for 20 days was evaluated. No differences in total volatile basic nitrogen (TVB-N), pH, carbohydrate or protein content of mucus were observed between the slaughter methods. Ice-slaughtered fish had lower bacteria counts at the beginning of storage, but higher counts than fish slaughtered by electricity at the end of storage (p < 0.05). However, no significant differences in the shelf life were observed between the slaughter methods evaluated (limit of acceptability – counts > 3 × 106 CFU g−1 – attained after 13–16 days). Results indicated that the chemical parameters evaluated have a limited applicability to assess the shelf life of grass carp stored in ice, since pH limit (6.8) was exceeded after 4 days, while TVB-N limit (30 mg%) was not attained after 20 days of storage.  相似文献   
994.
寿命分布类型的优选是产品可靠性分析的重要课题。在试验数据为小样本的情形下,仅仅利用试验数据来确定寿命分布类型存在着一定的困难。通过证据理论来综合利用小样本试验数据和专家经验来优选寿命分布类型是一个有效的解决途径。  相似文献   
995.
A life prediction model that was originally developed for the axial loading of unidirectional metal matrix composites (MMCs) undergoing combined thermal and mechanical loading is extended to the axial loading of cross-ply MMCs by adding an internally initiated matrix fatigue damage term. This new term accounts for the growth of cracks that initiate at the location where fibre–matrix separation occurs in the transversely-oriented plies. A comparison of the model predictions to experimental data on SCS-6/Timetal 21S shows that the model reasonably accounts for the dependence of applied stress, temperature and environment, as well as cyclic frequency. The dominant damage accumulation process for cross-ply MMCs with weak fibre–matrix bonds is described by this internally initiated matrix fatigue damage process for most stress–temperature cycle combinations. However, the fibre-dominated damage accumulation process operates under in-phase TMF when both stress and temperature are high. Environment-enhanced matrix fatigue is the dominant damage accumulation process under isothermal fatigue when stress is low and temperature is high.  相似文献   
996.
The small crack effect was investigated in two high-strength aluminium alloys: 7075-T6 bare and LC9cs clad alloy. Both experimental and analytical investigations were conducted to study crack initiation and growth of small cracks. In the experimental program, fatigue tests, small crack and large crack tests were conducted under constant amplitude and Mini-TWIST spectrum loading conditions. A pronounced small crack effect was observed in both materials, especially for the negative stress ratios. For all loading conditions, most of the fatigue life of the SENT specimens was shown to be crack propagation from initial material defects or from the cladding layer. In the analysis program, three-dimensional finite element and weight function methods were used to determine stress intensity factors and to develop SIF equations for surface and corner cracks at the notch in the SENT specimens. A plasticity-induced crack-closure model was used to correlate small and large crack data, and to make fatigue life predictions. Predicted crack-growth rates and fatigue lives agreed well with experiments. A total fatigue life prediction method for the aluminium alloys was developed and demonstrated using the crack-closure model.  相似文献   
997.
苏晓维  朱世杰 《钢铁》1995,30(2):52-57
分别从蠕变裂纹扩展的控制参数,临界裂纹长度剩余寿命三方面对HK40转化管进行了结构完整性研究。研究表明:能量率积分(C)是蠕变裂纹扩展的控制参数;用损伤分数的概念确定了构件的临界裂纹长度;并分别采用实验数据与能量率积分关联法和Webster模型法对服役81000h的HK40转化管进行了剩余寿命估算,结果表明Webster模型法是一种简单可靠的剩余寿命评价方法。  相似文献   
998.
The propagation of fatigue cracks in framed metal structures, usually described by Linear Elastic Fracture Mechanics, is analysed here and described by a numerical method based on classical beam theory. A procedure to be used in practice for the evaluation of stiffness degradation and energy release rate is presented. The procedure uses formulae which are explicitly given for statistically determinate beam structures that are being progressively damaged. If implemented into any beam-oriented finite element code as shown here, the proposed approach allows one to deal also with redundant structures.  相似文献   
999.
王亚枫  杨明家 《鞍钢技术》1998,(11):50-53,F004
本钢5号高炉于1996年4月1日停炉中修,介绍了5号高炉中修前的生产操作情况及存在的问题,总结了炉皮,耐火砖衬,冷却壁的破损情况,分析了破损原因,并提出了改进意见及延长高炉使用寿命的措施。  相似文献   
1000.
攀钢转炉采用溅渣护炉提高炉龄已经取得了很好的成绩。本文主要报告V.Ti氧化物对炉渣熔点,粘度和MgO饱和溶解度影响的研究结果,并提出了有关溅渣护炉渣系参数的建议。  相似文献   
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