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101.
In the workload control literature, the Load-Oriented Order Release (LOOR) approach has been neglected since its robustness was questioned at the end of the 1990s. This paper revisits LOOR and evaluates whether its performance can be improved in two ways. First, an intermediate pull release mechanism is added to avoid starvation between periodic release events. This mechanism was recently shown to be effective at improving the performance of a state-of-the-art release method known as LUMS COR. Second, an integer linear programming model is used to manage the trade-off between the timing and load balancing functions of order release. The two refinements are assessed using simulations of different shop configurations, which allow us to evaluate robustness. Results demonstrate that the refinements contribute to improving the performance of LOOR such that it can even outperform LUMS COR. Perhaps counter-intuitively, putting more emphasis on load balancing than on the urgency of individual orders is shown to lead to a lower percentage of tardy orders. Overall, the improvements mean that concerns about LOOR’s robustness are no longer valid – it now appears suitable for a wide range of shops found in practice.  相似文献   
102.
为了消除小片距、复杂片型高效表冷器在湿工况下运行时产生的“水塞”问题和进一步提高这类表冷器的热工性能,本文从凝结方式的理论分析出发,介绍了在表冷器上制作亲水性膜的方法,从理论上分析了这种亲水性膜的结构与亲水性的关系,从实践上给出了这种亲水性膜对表冷器的热工性能的新贡献,为研制高效紧凑式表冷器提供了可喜的前景。  相似文献   
103.
The present research examined whether the observation of emotional expressions rapidly induces congruent emotional experiences and facial responses in observers under strong test conditions. Specifically, participants rated their emotional reactions after (a) single, brief exposures of (b) a range of human emotional facial expressions that included (c) a neutral face comparison using a procedure designed to (d) minimize potential experimental demand. Even with these strong test conditions in place, participants reported discrete expression-congruent changes in emotional experience. Participants’ Corrugator supercilii facial muscle activity immediately following the presentation of an emotional expression appeared to reflect expressive congruence with the observed expression and a response indicative of the amount of cognitive load necessary to interpret the observed expression. The complexity of the C. supercilii response suggests caution in using facial muscle activity as a nonverbal measure of emotional contagion.
David H. ZaldEmail:
  相似文献   
104.
This paper analyzes factors that affect net migration rates in counties in the U.S. Great Plains between 1930 and 1990, emphasizing the roles of weather (especially drought), environmental amenities, employment, and population, making use of a rich county-level data set. Using a pooled time series model the paper shows that environment is important in population processes, with weather and agricultural change more important in the 1930s and 1940s, and environmental amenities more important in later time periods. The paper provides important insights into how environmental impacts on migration might change over time, and how those changes might be measured.  相似文献   
105.
杨帆  颜晖 《城市观察》2011,12(2):179-185
城市化对于城市环境的一个重要影响是热岛效应。为了研究上海市2007年来城市化进程对热岛效应的影响,采用遥感与GIS相结合的方法来定量的分析城市热环境的时空变化。根据2007年的LandsatTM影像提取了研究区的土地覆盖以及亮温信息,在此基础上通过统计分析和GIS的缓冲区分析对上海地区的热岛空间变化及其与土地覆盖变化的关系进行了深入研究。分析结果表明,城市热岛与城区的空间分布之间存在明显的一致性。  相似文献   
106.
Data were collected from a stratified sample of district nurses in the greater Stockholm area on four occasions during one year using questionnaire techniques (to assess psychosocial working conditions and social networks, and self-reported health sums); as well as physiological measurement techniques. Three groups of district nurses were compared: group A, those working independently in the 'traditional' role but outside primary health care centres; group B, those working independently in the 'traditional' role but in primary health care centres; and group C, those working in the model role as part of primary health care teams. The study focused on the effects of these different work environments on the district nurse's psychological and somatic health, and their physiological state.

The data suggested that district nurses in the primary care teams (group C) had a lower objective work load than those working in the more traditional role. Despite this, they reported a less favourable balance (ratio) of work demands to decision latitude. They reported more 'problems' and 'conflicts' at work than did the other district nurses. However, such 'problems' were diminishing during the study period, which could mean that successive adaptation to the 'new' situation was occurring. The 'conflicts', on the other hand, remained. This may indicate that despite this adaptation, the district nurses in the primary care teams were struggling with their new work roles. It points to the need for organizational support during this important change process. The district nurses in group B (traditional role but in a primary health care centre) had the highest objective work load and showed physiological reactions in terms of elevated plasma cortisol levels in the morning, high systolic blood pressure and sleep disturbances.  相似文献   
107.
对余热利用项目的评价,应是综合性的多目标评价。本文运用模糊集合论,井综合运用系统工程、计算机科学等领域的理论和技术,提出一套余热利用综合评价指标体系,建立了模糊综合评价数学模型和相应的计算机评价软件。在对实际的余热利用项目的应用中,收到了良好的效果。  相似文献   
108.
本文将含有电力的市场视为电力无法交易的不完全市场,利用Davis不完全市场定价理论给出了欧式热率相关期权的定价公式。在特殊电力价格模型下,得到了期权价格的解析解。  相似文献   
109.
Integrated assessment of operational and environmental performance of the production system requires mapping of all the processes and activities in the form of their resource utilisation efficiency. Prior research indicates that most lean assessment tools and techniques have studied operational dimensions ignoring environmental aspect as a part of the assessment tool. Moreover, movement towards the greener production system has become a key strategic consideration for organisations to maintain a competitive edge and to remain as market winners. Continuous assessment in both, lean and green, dimensions is crucial in improving the overall performance through efficient utilisation of the available resources. In lean environment, value stream mapping (VSM) allows assessment of operational performance through identification of non-value adding activities in time units but fails to integrate inefficiencies related to material and energy utilisation. The tool-like material flow cost accounting (MFCA) is able to assess the environmental performance through physical and monetary evaluation of material flow within the production system. This paper presents, a novel tool, value–value load diagram (VVLD), for modelling and evaluating the operational (lean) and environmental (green) performance of the production system. VVLD graphically represents resource consumption, value addition and performance improvement opportunities within the production system by integrating VSM, MFCA and pinch analysis methodology. VVLD permits evaluation of the lean–green performance in terms of the eco-leanness index and also exposes the improvement opportunities by pinch point location. Some common generic scenarios for improvement in the eco-leanness index are demonstrated using VVLD. Application of VVLD along with the developed computer-based support system (CBSS) is demonstrated for a manufacturing SME in India, allowing the managers to evaluate and tune their processes for improved resource utilisation efficiency.  相似文献   
110.
用线性摄动法给出了铸件在表面形状呈正弦变化的有限厚度铸型上凝固的三维热传导问题的数学模型,结合自变量变换法与有限差分法求解了热传导方程的数值解,给出了相变面随时间的变化过程和铸件的温度场分布情况.  相似文献   
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