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71.
《圆圆曲》是吴伟业七言歌行的代表作之一。明末清初动荡的社会背景,陈圆圆风雨飘摇的身世遭际,引发了诗人的创作灵感,也赋予了该诗巨大的历史价值,故历来此法备受关注,研究成绩斐然。本文梳理了相关研究资料,试图从其历史真实性、创作时间、主题意旨、艺术手法,及与《长恨歌》等同类诗作的比较研究等方面,对近三十年来《圆圆曲》的研究现状做一综述,以期在总结中理清脉络,进而寻求新的学术研究空间。  相似文献   
72.
Recently, Akyildiz called for further work on non-Poisson models for communication arrivals in distributed networks such as cellular phone systems. The basic ‘random’ model for stochastic events is the Poisson process; for events on a line this resuits in an exponential disiribuuon of intervals between events. Network designers and managers need too monotor and quantify call clustering in order to optimize resaurce usage; the natural reference state from which to measure departures is that arising from a Poisson, process of calls. Here we consider gamma distributions, which contain exponential distributions as a special case. The surface representing gamma models has a natural Riemannian information metric and we obtain some geodesic sprays for this metric. The exponential distributions form a 1-dimensional subspace of the 2-dimensional space of all gamma distributions, so we have an isometric embedding of the random model as a subspace of the gamma models. This geometry may provide an appropriate structure on which to represent clustering as quantifiable departures from randomness and on which to impose dynamic control algorithms to optimize traffic at receiving nodes in distributed communication networks. In practice, we may expect correlation between call arrival times and call duration, reflecting for example peaks of different users of internet services. This would give rise to a twisted product of two surfaces with the twisting controlled by the correlation. Though bivariate gamma models do exist, such as Kibble's, none has tractabie information geometry nor sufficiently general marginal gammas,but a simulation method of approach is suggested.  相似文献   
73.
Grandparents’ regular care for children while parents work has been mostly studied from the parental perspective. This paper focuses on the grandparents. Using the Australian Bureau of Statistics Time Use Survey 2006 (N = 7672) we investigate regular-caring grandparents’ demographic characteristics, which childcare activities they undertake, and how regular childcare provision relates to their time in other activities, subjective time pressure and satisfaction. Results indicate the correlates and nature of regular care differ by gender. Regular and non-regular-caring grandmothers’ relative time allocation to different childcare tasks barely differs, while regular-caring grandfathers’ care includes a much higher proportion of active care and travel than non-regular-caring grandfathers’. Regular care provision is associated with less leisure than non-regular-caring counterparts for both genders, but with only grandmothers’ housework, personal care and sleep time. Providing regular care doubles the likelihood of grandmothers reporting high subjective time pressure compared to non-regular-caring grandmothers; there is no association between regular care and time pressure for grandfathers. We conclude that in taking on regular care, grandparents echo the gender patterns found among parents, namely that it is women who are disproportionately impacted by meeting family care needs.  相似文献   
74.
This paper studies the effects of non-normality and autocorrelation on the performances of various individuals control charts for monitoring the process mean and/or variance. The traditional Shewhart X chart and moving range (MR) chart are investigated as well as several types of exponentially weighted moving average (EWMA) charts and combinations of control charts involving these EWMA charts. It is shown that the combination of the X and MR charts will not detect small and moderate parameter shifts as fast as combinations involving the EWMA charts, and that the performana of the X and MR charts is very sensitive to the normality assumption. It is also shown that certain combinations of EWMA charts can be designed to be robust to non-normality and very effective at detecting small and moderate shifts in the process mean and/or variance. Although autocorrelation can have a significant effect on the in-control performances of these combinations of EWMA charts, their relative out-of-control performances under independence are generally maintained for low to moderate levels of autocorrelation.  相似文献   
75.
学习是人类社会永恒的主题。为了更好地利用过去的经验,增强学习效果,个人和组织进行学习迁移具有重要意义。学习迁移是指将在以往通过学习或解决问题所获得的经验,用于解决之后所遇到的问题。本文力图建立系统的学习迁移理论,研究人、问题、环境的因素对于学习迁移的影响。本文采用理论推导的研究方法,在前人研究的基础上,提出相应的理论模型。本文运用系统的观点,构建了学习迁移的PPEE理论模型,认为人的因素、问题的因素、人和问题的交互作用、以及环境的调节作用,会共同影响学习迁移的效果。本理论主要从五个方面论述学习迁移的机制。首先,将人的因素按照不同层面划分为后端基本能力、中端心理过程、前端知识结构,讨论了其各自对学习迁移效果的直接影响。其次,将问题的因素划分为形象相似性和抽象相似性,并根据这两个维度构建了四种问题间关系类型,并探究了其与学习迁移效果之间的关系。第三,同时考虑人的因素和问题的因素,研究了二者之间的互动对于学习迁移效果的影响。第四,将环境因素划分为时间紧迫性和空间重要性两个维度,探讨了人和环境,以及问题和环境之间的互动对学习迁移效果的影响。第五,基于系统整体的方面,研究人、问题、环境三者之间的互动对学习迁移效果的交互影响。本文还认为,该模型不仅适用于个人,也同样适用于团队、组织、地区、甚至国家和社会等各个层面,影响各个层面主体的学习迁移。本文最后总结了研究的理论和实践贡献,并提出了未来研究课题。本文对丰富学习理论、特别是学习迁移理论,以及推动教育和管理实践的发展进步具有重要的意义。  相似文献   
76.
In some situations, an appropriate quality measure uses three or more discrete levels to classify a product characteristic. For these situations, some control charts have been developed based on statistical criteria regardless of economic considerations. In this paper, we develop economic and economic statistical designs (ESD) for 3-level control charts. We apply the cost model proposed by Costa and Rahim.[Economic design of X charts with variable parameters: the Markov chain approach, J Appl Stat 28 (2001), 875–885] Furthermore, we assume that the length of time that the process remains in control is exponentially distributed which allows us to apply the Markov chain approach for developing the cost model. We apply a genetic algorithm to determine the optimal values of model parameters by minimizing the cost function. A numerical example is provided to illustrate the performance of the proposed models and to compare the cost of the pure economic and ESD for three-level control charts. A sensitivity analysis is also conducted in this numerical example.  相似文献   
77.
平稳性检验是时间序列回归分析的一个关键问题,已有的检验方法在处理海量时间序列数据时显得乏力,检验准确率有待提高。采用分类技术建立平稳性检验的新方法,可以有效地处理海量时间序列数据。首先计算时间序列自相关函数,构建一个充分非必要的判定准则;然后建立序列收敛的量化分析方法,研究收敛参数的最优取值,并提取平稳性特征向量;最后采用k-means聚类建立平稳性分类识别方法。采用一组模拟数据和股票数据进行分析,将ADF检验、PP检验、KPSS检验进行对比,实证结果表明新方法的准确率较高。  相似文献   
78.
通过建立包括陆地、湿地和海洋的碳承载力、碳超载率的计算模型,采用供需平衡法建立了区域碳锁定时间和趋势的判定模型。以有着“植物王国”和“基因宝库”之称以及水电资源相对丰富的云南省为例,对该省的碳锁定时间、趋势进行了实证研究。实证分析结果显示,云南省自2002年后开始出现了碳锁定现象且趋势越来越严重,若不进行强有力的外界干扰,这种趋势将一直延续下去。结合即使“十一·五”低碳目标的完成也没能减轻云南省碳锁定加剧的趋势,提出把减轻碳超载、控制能源消费总量、提升碳承载力纳入低碳经济发展的目标管理。  相似文献   
79.
The mean residual life measures the expected remaining life of a subject who has survived up to a particular time. When survival time distribution is highly skewed or heavy tailed, the restricted mean residual life must be considered. In this paper, we propose an additive–multiplicative restricted mean residual life model to study the association between the restricted mean residual life function and potential regression covariates in the presence of right censoring. This model extends the proportional mean residual life model using an additive model as its covariate dependent baseline. For the suggested model, some covariate effects are allowed to be time‐varying. To estimate the model parameters, martingale estimating equations are developed, and the large sample properties of the resulting estimators are established. In addition, to assess the adequacy of the model, we investigate a goodness of fit test that is asymptotically justified. The proposed methodology is evaluated via simulation studies and further applied to a kidney cancer data set collected from a clinical trial.  相似文献   
80.
《采蘩》为写召南贵族夫人采集白蒿以奉祭祀之作,《采蘋》为写将要出嫁的召南贵族少女采集浮萍、水藻后举行婚前教成祭祀仪式之作,二诗皆当作于周平王(前770年~前720年在位)初年;《甘棠》为召伯虎卒后故西周王畿遗民的悼亡怀念之作,当作于周平王元年至十二年(前770年~前759年)"二王并立"之时。  相似文献   
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