Results of the ASTM field test of tristimulus weighting functions

In 1993, the American Society for Testing and Materials carried out a field test of newly calculated tristimulus weighting factors. These weighting factors had been calculated by a method proposed by Venable. the test also included a method of correction for bandpass dependence put forth by Stearns. the purpose of the trial was to assess the possible reduction in bandpass dependence introduced by each of these sets of weights. A large number of sets of spectral data were gathered from the cooperators in the field test. Results of integration by the various sets of tristimulus weighting factors were calculated. A total of 15 120 color differences were calculated and statistics were derived to test the probable error resulting from each method of correction. Errors attributable to bandpass dependence were on the order of a few tenths to as much as one CIELAB unit when uncorrected weight sets were used. These errors could be reduced to a few hundreths of a CIELAB unit, and in some cases to a few thousandths of a unit, by employing one correcting strategy or the other. an overall mix of strategies was ultimately chosen to minimize the bandpass dependence over the entire range of weight sets. Utilizing this mixed strategy, the median error introduced into 10-nm integration by bandpass dependence was only 0.004 CIELAB units. © 1995 John Wiley & Sons, Inc.     

Influence of depth-thickness ratio of mining on the stability of a bedding slope with its sliding surface in concave deformation

In order to study the influence of depth-thickness ratio on bedding slope stability, whose sliding surface is flexural concave in shape under mining conditions, this paper aims to study the characteristics of deformation and damage of bedding sliding with depth-thickness ratios of 200:1, 150:1, 120:1, 100:1 and 50:1by adopting numerical simulation analysis software combined with laboratory-made ‘‘under the influence of mining variable sliding surface slope similar simulation test bed", and to propose identification methods for slope stability under the influence of mining. The results show that mining activities under the slope reduce slope stability. With a decrease in the mining depth ratio, the influence of mining on the slope increases gradually, and the damage to the slope gradually expands, the stability of the slope gradually reduces, fracture occurs on the slope toe and the central fissure gradually develops to the surface,and reaches slide threshold when the depth-thickness ratio is 50:1.     

中国传统性伦理思想对大学生性教育的影响

性伦理思想对我国当代大学生性教育具有十分重要的意义,通过对中国传统性伦理思想的研究分析,探索其对大学生性教育产生的主要影响,为进一步推进当代大学生的性教育提供合理性依据。     

Limit load and shakedown analysis of plastic structures under stochastic uncertainty

Problems from plastic analysis are based on the convex, linear or linearised yield/strength condition and the linear equilibrium equation for the stress (state) vector. In practice one has to take into account stochastic variations of several model parameters. Hence, in order to get robust maximum load factors, the structural analysis problem with random parameters must be replaced by an appropriate deterministic substitute problem. A direct approach is proposed based on the primary costs for missing carrying capacity and the recourse costs (e.g. costs for repair, compensation for weakness within the structure, damage, failure, etc.). Based on the mechanical survival conditions of plasticity theory, a quadratic error/loss criterion is developed. The minimum recourse costs can be determined then by solving an optimisation problem having a quadratic objective function and linear constraints. For each vector a(·) of model parameters and each design vector x, one obtains then an explicit representation of the “best” internal load distribution F^∗. Moreover, also the expected recourse costs can be determined explicitly. Consequently, an explicit stochastic nonlinear program results for finding a robust maximal load factor μ^∗. The analytical properties and possible solution procedures are discussed.     

浅析金鸡拦河闸重建工程的环境保护与防治控制

论述了泉州市金鸡拦河闸重建工程的意义,分析了重建工程对河道上下游水生态环境的影响,提出了环境保护与污染防治措施。     

Does the ‘forbidden zone’ for sleep onset influence morning shift sleep duration?

Shiftwork researchers have concentrated on the problems on the night shift, and have tended to neglect the truncation of sleep that can occur before morning, or ‘early’, shifts. We examined the sleep timing and duration between morning shifts of shiftworkers on a variety of shift systems. The extent of morning shift sleep truncation depended very largely on the time at which individuals had to leave home. Further, there was some suggestive evidence that the failure of individuals to compensate by going to sleep earlier was not simply due to social pressures to stay up. Rather it would appear to have depended, at least in part, on the biological clock determined ‘forbidden zone’ for sleep that occurs shortly before habitual sleep onset.     

纤维缠绕外压容器稳定性最佳铺层分析

在纤维缠绕压力容器设计中，纤维缠绕的方向及各方向纤维用量配比是关键问题。过去的研究中，这一问题一直没能得到很好地解决，特别是各方向纤维用量问题。本文在文献［１～４］的基础上，以加权因子和铺设角为参量给出了对称多层正交各向异性外压容器筒体失稳的最佳铺层理论值。得出了加权因子ｓ取最佳值的范围为０＜ｓ＜０．２５的结论。文中算例表明，按最佳取值给出的临界压力较其它情况有较大幅度的提高。     

Mitigation of Damages to Electric Utilities Due to High Winds

Extreme winds, hurricanes, and tornadoes produce significant damage to electrical transmission and distribution line structures. The damage produces loss of power to the affected communities for a variable length of time, depending on severity of damage. Most institutions whose operations would be life threatening in the event of power failure have emergency power. However, loss of power to both residences and businesses can have economic impact on the community in the form of temporary housing shortages and loss of business. Utility companies seem to cope with wind damage fairly well, following risk management procedures in designing for wind and in providing alternate routing for distribution lines. However, continuing research and developments are needed to keep abreast of the problem.     

喷射式凝汽器传热性能影响因素分析

空冷机组是解决富煤贫水地区电力工业发展问题的有效措施,近年来在国内外发展迅速。作为海勒式间接空冷系统的关键设备,喷射式凝汽器的性能与整个空冷机组的性能直接相关。介绍了国内外喷射式凝汽器的研究现状,分析了影响喷射式凝汽器传热性能的主要因素。     

热处理工艺对SCM822H钢的组织及性能的影响

对Cr-Mo系列有代表性钢种SCM822H的临界点、连续冷却曲线进行了测试,探讨了不同热处理状态对其晶粒度、组织和性能的影响,为进一步优化和完善该钢的生产工艺提供了理论依据。