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71.
SONET (Synchronous Optical NETworks) add-drop multiplexers (ADMs) are the dominant cost factor in the WDM(Wavelength Division Multiplexing)/SONET rings. The number of SONET ADMs required by a set of traffic streams is determined by the routing and wavelength assignment of the traffic streams. Previous works took as input the traffic streams with routings given a priori and developed various heuristics for wavelength assignment to minimize the SONET ADM costs. However, little was known about the performance guarantees of these heuristics. This paper contributes mainly in two aspects. First, in addition to the traffic streams with pre-specified routing, this paper also studies minimizing the ADM requirement by traffic streams without given routings, a problem which is shown to be NP-hard. Several heuristics for integrated routing and wavelength assignment are proposed to minimize the SONET ADM costs. Second, the approximation ratios of those heuristics for wavelength assignment only and those heuristics for integrated routing and wavelength assignment are analyzed. The new Preprocessed Iterative Matching heuristic has the best approximation ratio: at most 3/2. 相似文献
72.
In Sweden, government-mandated paid parental leave has been available to both mothers and fathers since 1974. By 2006, each parent had two non-transferable leave months and nine additional months to share. From the beginning, parental leave was presented as a policy designed to promote gender equality, with women and men having equal opportunities and responsibilities to contribute economically to the family and care for children. Sweden thus provides a unique setting to explore whether social policy can be an important instrument for changing the gender contract. Analysing survey data from 356 fathers working in large private companies, we found that the amount of parental leave days taken had positive effects on several aspects of fathers’ participation in childcare and on their satisfaction with contact with children, controlling for other factors contributing to fathers’ participation in childcare. Our findings suggest that the full potential of Sweden's parental leave policy for degendering the division of labour for childcare will not likely be met until fathers are strongly encouraged by social policy to take a more equal portion of parental leave. 相似文献
73.
科技传播研究:“普及范式”和“创新范式” 总被引:2,自引:0,他引:2
国内科技传播研究在近几年渐见繁荣之势。为了促进科技传播研究在国内更好地发展,文章讨论了已得到一定发展的“普及范式”和正在发展中的“创新范式”,认为面向未来知识经济的发展,需要推进“创新范式”的科技传播研究。 相似文献
74.
Ranked set sampling is a sampling approach that leads to improved statistical inference in situations where the units to be sampled can be ranked relative to each other prior to formal measurement. This ranking may be done either by subjective judgment or according to an auxiliary variable, and it need not be completely accurate. In fact, results in the literature have shown that no matter how poor the quality of the ranking, procedures based on ranked set sampling tend to be at least as efficient as procedures based on simple random sampling. However, efforts to quantify the gains in efficiency for ranked set sampling procedures have been hampered by a shortage of available models for imperfect rankings. In this paper, we introduce a new class of models for imperfect rankings, and we provide a rigorous proof that essentially any reasonable model for imperfect rankings is a limit of models in this class. We then describe a specific, easily applied method for selecting an appropriate imperfect rankings model from the class. 相似文献
75.
《发展和完善南宁市新型农村合作医疗制度研究》课题组 《创新》2008,2(3)
近年来,党和政府一直把发展和完善新型农村合作医疗制度作为改善民生的一项重要工作。南宁市新型农村合作医疗尽管有了较大的发展,但与同为西部省会城市的西安、昆明、成都相比还存在不少差距。这就需要结合地方实际,从运行机制、资金监管、信息化管理、人才建设等软、硬件方面破解新型农村合作医疗制度发展和完善的难题。 相似文献
76.
77.
文章对人力资源系统与公司绩效关系实证研究中影响其效应大小的围绕项目、时间和评定者测量信度的随机误差和系统误差进行评述与分析,介绍基于构思水平理解评定者间信度的思路,较好解决了实证中的数据来源问题.并提出对管理感知这一新的系统误差的研究.总结改善信度的方法和探索,讨论了人力资源系统测量中需要改进的地方和进一步的研究方向. 相似文献
78.
通过分析宜昌市自然地理和人文地理环境,对宜昌城市形象进行了定位,提出了建设具有“山水园林特色的水电旅游城市”的理念,探讨了宜昌城市规划合理利用地理环境的方略与措施。 相似文献
79.
我国是目前国际上遭受反倾销调查最多的国家,国外反倾销给我国出口贸易造成了巨大损失。会计是反倾销诉讼中的一个关键因素。文章针对会计在我国企业应对反倾销中的作用和我国企业应对反倾销中存在的会计问题进行了分析,在此基础上提出了我国企业从会计角度应对反倾销的对策与建议。 相似文献
80.
James P. McDermott G. Jogesh Babu John C. Liechty Dennis K. J. Lin 《Statistics and Computing》2007,17(4):311-321
We consider the problem of density estimation when the data is in the form of a continuous stream with no fixed length. In
this setting, implementations of the usual methods of density estimation such as kernel density estimation are problematic.
We propose a method of density estimation for massive datasets that is based upon taking the derivative of a smooth curve
that has been fit through a set of quantile estimates. To achieve this, a low-storage, single-pass, sequential method is proposed
for simultaneous estimation of multiple quantiles for massive datasets that form the basis of this method of density estimation.
For comparison, we also consider a sequential kernel density estimator. The proposed methods are shown through simulation
study to perform well and to have several distinct advantages over existing methods. 相似文献