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31.
基于维纳的经典控制模式,依照接入控制、过滤控制、编辑控制、分析控制四个流程,尝试建构了网络内容的技术控制模式。此模式着眼于复杂的网络传播环境,反映了多传播时代的多向反馈,体现了效果/批判的范式融合,综合了立体多元的控制手段。  相似文献   
32.
张和清 《社会》2010,30(2):20-44
本文借助“权力的文化网络”视角,深层再现云南省一个少数民族山区--蚌岚河槽(村庄)传统主族控制和毕摩操控的村落政治格局。作者认为,1949年以前槽区的社会政治局面是主族控制和毕摩操控,主族及其首领毕摩依靠乡村文化网络获得权威和认受性,他们在权力的文化网络中发挥着组织领导的作用,凭借对乡村文化网络(族群内部的宗族关系和宗教信仰以及族群关系等)的操控,主族及其首领毕摩有力地控制着乡村社会。  相似文献   
33.
In oncology, it may not always be possible to evaluate the efficacy of new medicines in placebo-controlled trials. Furthermore, while some newer, biologically targeted anti-cancer treatments may be expected to deliver therapeutic benefit in terms of better tolerability or improved symptom control, they may not always be expected to provide increased efficacy relative to existing therapies. This naturally leads to the use of active-control, non-inferiority trials to evaluate such treatments. In recent evaluations of anti-cancer treatments, the non-inferiority margin has often been defined in terms of demonstrating that at least 50% of the active control effect has been retained by the new drug using methods such as those described by Rothmann et al., Statistics in Medicine 2003; 22:239-264 and Wang and Hung Controlled Clinical Trials 2003; 24:147-155. However, this approach can lead to prohibitively large clinical trials and results in a tendency to dichotomize trial outcome as either 'success' or 'failure' and thus oversimplifies interpretation. With relatively modest modification, these methods can be used to define a stepwise approach to design and analysis. In the first design step, the trial is sized to show indirectly that the new drug would have beaten placebo; in the second analysis step, the probability that the new drug is superior to placebo is assessed and, if sufficiently high in the third and final step, the relative efficacy of the new drug to control is assessed on a continuum of effect retention via an 'effect retention likelihood plot'. This stepwise approach is likely to provide a more complete assessment of relative efficacy so that the value of new treatments can be better judged.  相似文献   
34.
一、引言(一)现实背景从2000年9月21日起,我国利率市场化改革进入实质性阶段,预计三年内完成。利率市场化是一场系统性的金融革命,必将对经济金融领域的方方面面产生重要影响。商业银行应积极采取措施,应对利率市场化将带来的一系列风险。近几年,我国发行了大量的国债和金融债,  相似文献   
35.
金融风险度量VaR与CVaR方法的比较研究及应用   总被引:1,自引:0,他引:1  
风险价值(VaR)是近年来受到国际金融界的广泛支持和认可的一种度量金融风险的工具。文章指出了风险价值(VaR)模型两个重大的缺陷,并对它和条件风险价值(CVaR)金融风险度量模型进行了详细的介绍和对比分析,给出了它们的共同点和CVaR在投资组合应用中的优势,结合中国金融市场的实际情况,指出CvaR在中国金融市场中应用应注意的问题,对其应用前景提出了新的思路。  相似文献   
36.
The use of complex sampling designs in population-based case–control studies is becoming more common, particularly for sampling the control population. This is prompted by all the usual cost and logistical benefits that are conferred by multistage sampling. Complex sampling has often been ignored in analysis but, with the advent of packages like SUDAAN, survey-weighted analyses that take account of the sample design can be carried out routinely. This paper explores this approach and more efficient alternatives, which can also be implemented by using readily available software.  相似文献   
37.
We discuss in the present paper the analysis of heteroscedastic regression models and their applications to off-line quality control problems. It is well known that the method of pseudo-likelihood is usually preferred to full maximum likelihood since estimators of the parameters in the regression function obtained are more robust to misspecification of the variance function. Despite its popularity, however, existing theoretical results are difficult to apply and are of limited use in many applications. Using more recent results in estimating equations, we obtain an efficient algorithm for computing the pseudo-likelihood estimator with desirable convergence properties and also derive simple, explicit and easy to apply asymptotic results. These results are used to look in detail at variance minimization in off-line quality control, yielding techniques of inferences for the optimized design parameter. In application of some existing approaches to off-line quality control, such as the dual response methodology, rigorous statistical inference techniques are scarce and difficult to obtain. An example of off-line quality control is presented to discuss the practical aspects involved in the application of the results obtained and to address issues such as data transformation, model building and the optimization of design parameters. The analysis shows very encouraging results, and is seen to be able to unveil some important information not found in previous analyses.  相似文献   
38.
The use of the np chart for monitoring fraction-defective is well-established, but there are a number of relatively simple alternatives based on run-lengths of conforming items. Here, the RL2 chart, based on the moving sum of two successive conforming run-lengths, is investigated in order to provide SPC practitioners with clear-cut guidance on the comparative performance of these competing charts. Both sampling inspection and 100% inspection are considered here, and it is shown that the RL2 chart can often be considerably more efficient than the np chart, but the comparative performance depends on the false-alarm rate used for the comparison. Graphs to aid parameter-choice for the RL2 chart are also provided.  相似文献   
39.
本文介绍了一种实用自适应PID控制器,它是以MCS-51系列单片微机为核心,采用PID控制规律结合参数辨识的控制算法,实现了PID参数完全在线自动整定。该控制器适用于被控制对象未知或慢时变的场合,既可替代常规PID控制器,也可作为分布式系统的低级智能控制器。  相似文献   
40.
本文讨论了电磁辐射、电源波动等干扰源,并分析这些干扰源怎样引起机器人控制系统、微机、微处理器的失灵和损坏。最后本文介绍了防止这些干扰的实用方法,它们包括有双层屏蔽、光电隔离、光纤传导等方法。  相似文献   
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