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1.
This article is the first of two consecutive reviews on the major empirical studies which have been carried out in an attempt to estimate the prevalence of child sexual abuse among females. The research is structured in terms of three sample categories: (a) probability and non-probability samples of the general population; (b) college student samples; and (c) clinical inpatient and outpatient samples. This part of the review deals with (a) and (b) and highlights a number of unresolved methodological issues which may contribute to the variance in reported prevalence rates. These include a myriad of definitions of child sexual abuse and different methods of eliciting information on possible histories of abuse. Despite these problems. taken as a whole the prevalence studies indicate the significant numbers of people who have experienced abuse and who are willing to disclose aspects of these abusive experiences. 相似文献
2.
建立了有柔性路径的FMS动态调度问题的模型.采用离线重调度的方法,提出一种结合离线重调度两种生成调度方式的方法来阐述FMS的有柔性路径动态调度问题.最后给出了该问题的遗传算法解决方法和计算示例. 相似文献
3.
In this paper we develop a study on several types of parallel genetic algorithms (PGAs). Our motivation is to bring some uniformity to the proposal, comparison, and knowledge exchange among the traditionally opposite kinds of serial and parallel GAs. We comparatively analyze the properties of steady-state, generational, and cellular genetic algorithms. Afterwards, this study is extended to consider a distributed model consisting in a ring of GA islands. The analyzed features are the time complexity, selection pressure, schema processing rates, efficacy in finding an optimum, efficiency, speedup, and resistance to scalability. Besides that, we briefly discuss how the migration policy affects the search. Also, some of the search properties of cellular GAs are investigated. The selected benchmark is a representative subset of problems containing real world difficulties. We often conclude that parallel GAs are numerically better and faster than equivalent sequential GAs. Our aim is to shed some light on the advantages and drawbacks of various sequential and parallel GAs to help researchers using them in the very diverse application fields of the evolutionary computation. 相似文献
4.
霍兰在复杂性系统科学方面提出复杂自适应系统(CAS)理论.他提出的涌现性理论对创新研究具有重要意义.对霍兰的科学思想渊源关系、遗传算法、CAS理论、涌现性方面的奠基性工作加以详细研究和评述,进而确立了霍兰在遗传算法、复杂性系统科学上的奠基性地位. 相似文献
5.
Jason P. Fine David V. Glidden Kristine E. Lee 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(1):317-329
Summary. We propose a simple estimation procedure for a proportional hazards frailty regression model for clustered survival data in which the dependence is generated by a positive stable distribution. Inferences for the frailty parameter can be obtained by using output from Cox regression analyses. The computational burden is substantially less than that of the other approaches to estimation. The large sample behaviour of the estimator is studied and simulations show that the approximations are appropriate for use with realistic sample sizes. The methods are motivated by studies of familial associations in the natural history of diseases. Their practical utility is illustrated with sib pair data from Beaver Dam, Wisconsin. 相似文献
6.
The epidemiology of schizophrenia among Caribbean-born and first- and second-generation migrants in Britain 总被引:1,自引:0,他引:1
Delroy M. Louden 《Journal of Social Distress and the Homeless》1995,4(3):237-253
The study of migrants in their new environments is often a useful means of investigating environmental influences on health. Migrants have been found to develop higher rates of mental illness compared to their counterparts who remain at home. These deleterious effects of migration have been attributed to selection factors and stressful life experiences. Migration from an agricultural and traditional society to an urban industrial society where value systems can be demanding, often leads to role strain and role conflict. These kinds of incongruities are the beginning of a series of stressful experiences that contribute to poor health/mental health status. The extent to which one experiences stress is dependent on a number of factors. First, it depends on the perceived difference between home and the new environment. Second, it depends on the cultural homogeneity of the new environment, that is, the extent to which the migrant is readily assimilated into the new culture or is able to maintain a traditional lifestyle by living in an ethnic enclave, and the psychological resources available to successfully access services in the new environment. This paper examines the rates, incidence, and prevalence of schizophrenia found in Caribbean-born immigrants to Britain, and first- and second-generation people of Caribbean background born in Britain. It is argued that Afro-Caribbean people in England are overrepresented in the diagnosis of schizophrenia. Factors that may contribute to this finding range from unemployment, social disadvantage status, social adversity, racism in the health and criminal justice systems, and misdiagnosis.This paper was completed when the author served as Distinguished Visiting Professor-William Patterson College, Wayne, New Jersey. 相似文献
7.
发生认识论的哲学来源 总被引:3,自引:0,他引:3
吴琳 《武汉理工大学学报(社会科学版)》2005,18(1):76-79
皮亚杰的发生认识论并不是一个纯粹的发展心理学理论,而是一个关于认知的结构及其发生与发展的理论。发生认识论的建立有其深厚的哲学根源:它是在批判传统认识论中的经验主义和理性主义的基础上建立起来的。皮亚杰看到,无论是经验主义方法,还是理性主义方法对于认知的结构及其发生与发展的解释都是片面的,因为前者忽视了结构,后者假设了结构而没有注意到结构发展的自然进程。皮亚杰在对两者辨证综合的基础上,提出“发生学的结构主义”,指出认识的发生与发展是因为我们作为生物先天地就包含着这样的结构,而且是因为我们作为生物对结构进行主动建构的结果。 相似文献
8.
柴水英 《浙江树人大学学报》2005,5(2):119-122
阐述了将两类技术组合的一种方法:用L-systems和遗传算法CA获取一种改写表达式描述树叶模型。L-systems用于构造给定改写表达式,而GA用于改写表达式的适应参数。介绍了用目标函数实现真值参数替换方法,研究结果表明,提出的方法能产生可以接受的输出效果。 相似文献
9.
本文分析了传统FAGM(1,1)模型建模过程中存在的误差,提出了一种基于Simpson公式改进的FAGM(1,1)模型。首先,基于分数阶累加生成算子和分数阶累减生成算子建立分数阶FAGM(1,1)模型。其次,利用Simpson积分公式对FAGM(1,1)模型的背景值进行改进,建立SFAGM(1,1)模型。进一步,应用遗传算法确定SFAGM(1,1)模型的最优阶数以提高模型的预测精度。最后,以中国人均GDP为例,对比分析GM(1,1)模型、Simpson改进的GM(1,1)模型(SGM(1,1))、FAGM(1,1)模型、SFAGM(1,1)模型的模拟结果,并对"十三五"时期的人均GDP进行预测,其结果表明SFAGM(1,1)模型比GM(1,1)、SGM(1,1)、FAGM(1,1)在人均GDP的预测方面有更高的精度,"十三五"期间人均GDP年平均增长率为10.64%,到2020年达到83146.97元,是2010年人均GDP的2.69倍,以2010年的人均GDP为基准,到2020年将能够实现翻一番的目标。 相似文献
10.
考虑多种安全设置策略的物流网络的选址-库存问题,不仅是选址、订货、运输和库存的集成优化,还需要考虑多种不同的安全库存设置和转运策略。因此,本文深入讨论了二级物流网络中的六种安全库存设置策略,构建了六种考虑不同安全库存设置的选址-库存模型。在考虑集中设置安全库存时,集中安全库存需要通过转载运输实现,因此需要将转载运输成本引入选址-库存模型之中,使新的选址-库存模型更加科学合理。另外,针对六种新的选址-库存模型,提出了基于个体成本差异分配的遗传算法,迭代搜索选址、分配、库存设置策略的优化组合。最后,通过数据实验验证了模型的有效性:(1)安全库存与转载运输之间存在此消彼长的背反关系;(2)安全库存设置和转载运输策略对总成本的影响取决于两种费率权重情况。本文的研究可以为二级物流网络的选址、订货和安全库存策略集成优化决策提供参考依据。 相似文献