An alternative work measurement method and its application to a manufacturing industry

Difficulties in determining the standard time justify the need to develop alternative methods to direct measurement procedures. The indirect methods which are comparison and prediction, standard data and formulation, predefined movement-time systems have several deficiencies in time measurement procedures. In this study, an alternative indirect work measurement method based on artificial neural networks (ANNs) is presented which is simple and inexpensive. For the application of the proposed method, the products that have similar production processes are selected among the whole product family produced in a manufacturing company. The standard times of the sampled products that are previously measured are used and the standard times of the remaining several products and semi-products are predicted by the proposed method. The model results show that the proposed method can be applied accurately in companies which produce similar products.     

Charging versus exclusion: Choice between recreation management tools

Overuse of recreation sites seems to justify regulation, and the principal tools for this are fee charging or physical exclusion. Both seem equally costly to administer. Both involve equal costs to consumers if recreationists visit from one origin, but if they come from different origins, costs may be greater and consumers' surplus less under either tool, depending on the shape of the demand curve. Which is the more equitable tool depends on the relative representation of rich and poor participants from near and distant origins. Potentially beneficial use of site revenues is an advantage of charging. Neither availability of substitutes nor variation in daily demand seems likely to change these results substantially, but a system of booking admissions before the trip outset might neutralize the advantages of charging. The optimal level of use varies with the regulatory tool chosen. The optimal admissions under exclusion could be fewer than or more than under charging, or may even be equal to unregulated use.     

降低铁路原油卸车蒸汽消耗的有效途径

针对卸油过程中单位油品蒸汽消耗量大的问题，制定出有效的解决措施，降低卸油消耗量。     

河流水质时间序列分析的自组织预测方法及应用

应用前苏联学者伊万年科基于生物控制论中的自组织原理提出的一种数据组合处理方法，有效地解决复杂非线性系统预测。以汾河某段的水污染时间序列监测数据为基础，建立了一个河流水质污染预测的自组织模型，其建模样本的拟合值和检验样本的预测值相对误差分别在３．１％和５．３％以内。结果表明，自组织模型能较好地描述水污染时间序列数据之间的非线性关系，适合复杂水环境污染系统的预测工作。     

“十五”期间沈阳市煤炭消费与大气污染相关性分析

通过对沈阳市“十五”期间经济发展所引起的煤炭消费量与大气污染之间的关系进行分析后可知,“十五”期间沈阳市煤炭消耗量与大气污染物排放量、大气环境质量均呈现为“负相关性”,经解析,“十五”期间由于沈阳市采取了煤炭管制、推行集中供热提高煤炭使用效率等手段,使得煤炭消费在增长的情况下大气污染物排放量降低、环境空气质量逐步改善,呈现为“负相关性”。     

沈阳市地铁一号线项目施工期环境影响及对策研究

通过对沈阳地铁一号钱施工期产生的环境影响综合分析,研究该项目在建设中产生的噪声、振动、废水、废气及固体废弃物等污染物产生的规律和发生量,并提出缓解和控制环境影响的措施。     

Time budgets and foraging in a Malagasy primate: do sex differences reflect reproductive condition and female dominance?

Female mammals commonly employ behavioral tactics of modulating activity levels and foraging behavior to counter the energetic burden of reproduction; these behavioral changes are reflected as intersexual differences. Traditional views of Malagasy primates posit that high reproductive costs select for female dominance which guarantees to energetically stressed females priority of resource access. I tested predictions regarding reproductive influences on sex differences in time budgets and foraging behavior using two groups of Milne-Edwards' sifaka (Propithecus diadema edwardsi) in southeastern Madagascar. Compared to males, females increased neither feeding nor resting time during gestation or lactation. Sex differences were essentially absent in all foraging time variables examined (time, duration, rate). In contrast, dietary composition diverged between the sexes in some months. The possibility that females selected particular food items to boost nutrient and energetic intake to meet increased requirements during reproduction must be further clarified with nutritional analyses. Sex differences in plant part choices coincided with lactation in one of the two study groups. Thus, the timing of sex differences in feeding patterns of P. d. edwardsi only partially supports the prediction that sex differences are most pronounced during the period of greatest female energetic demand. A comparative review indicated no tight association between female dominance and sex differences in foraging among Malagasy primates. Traditional female dominance theory falls short of explaining the observed patterns. The results of my study coupled with recent evidence suggest that non-behavioral tactics involving energy conservation and storage require further attention as mechanisms by which female lemurs cope with reproductive costs. Received: 12 June 1998 / Accepted after revision: 10 October 1998