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1.
机械产品的设计一直注重于市场需求和产品功能的开发,随着科学和技术的发展,环境因素变得越来越重要。 提出一种基于功能一环境一结构分析( FESA)与TRIZ的机械产品创新设计方法,通过分析机械产品结构之间的功能要素 以及功能要素与环境要素的相互作用关系,确定机械产品中存在的问题。建立根原因模型图,寻找结构设计上的不足和 缺陷,利用TRIZ创新理论来实现机械产品的改进创新。通过污水处理系统的创新设计实例验证了该方法的可行性。  相似文献   
2.
A proper monitoring of stochastic systems is the control charts of statistical process control and drift in characteristics of output may be due to one or several assignable causes. Although much research has been done on the design of control charts, the economic statistical design of the T2 control chart under the Weibull shock model with multiple assignable causes has not yet been addressed. Therefore, we tried to deal with it in this paper and thus we developed a cost model based on the variable sampling interval. We also give an example to support the practical use of T2 chart under the Weibull shock model with multiple assignable causes. Based on the optimization of the average cost per unit of time and taking into account the different combination values of Weibull distribution parameters, optimal values of design parameters were derived and calculated. Then, the cost models under the influence of single assignable cause and multiple assignable causes under the same cost and time parameters were compared. Also, a sensitivity analysis was conducted in which the variability of loss cost and design parameters due to change of cost and time and Weibull distribution parameters were evaluated.  相似文献   
3.
We show that the Lagrange multiplier (LM) unit root test exhibits size distortions when a break in the innovation variance exists but is ignored. We develop a modified LM unit root test that is based on a generalized least-squares transformation of the original series. The asymptotic null distribution of the new modified LM unit root test is derived. Finite-sample simulation evidence shows that the modified LM unit root test maintains its size and has reasonable power against the trend stationary alternative.  相似文献   
4.
湖南实施乡村振兴战略面临的主要问题是:农村基础设施改善,但部分乡村旧貌未改;农田荒芜严重,土地流转不畅;种养收入低下,农产销售困难;农村二三产业发展迟缓,集体合作社模式短缺;文化设施缺乏,风俗习惯落后;老农依然辛劳,养老问题难解。带来这些问题的原因主要有:认识存在偏差,发展缺乏资金与人才,集体经济脆弱,干部责任意识不强,缺少产业支撑,乡风治理乏力。文章从实际出发,提出了一系列政策建议:转变思想观念,改变投资取向;改善乡村交通,加强基础设施;完善村居环境,实施“五改五化”;推动土地流转,培育二三产业;壮大集体经济,发展合作组织;强化党组织建设,重视选人用人。  相似文献   
5.
In this paper, we consider the linear autoregressive model with varying coefficients θn∈[0,1). When θn tending to the unit root, the moderate deviation principle for empirical covariance is discussed, and as statistical applications, we provide the moderate deviation estimates of the least square and the Yule–Walker estimators of the parameter θn.  相似文献   
6.
In this article three unit root tests that allow for a break in both the seasonal mean and linear trend of the data are proposed. The tests, which can be seen as small-sample corrected versions of already known asymptotic tests, are shown to perform very well in simulations, and much better than their asymptotic counterparts.  相似文献   
7.
Structural breaks in the level as well as in the volatility have often been exhibited in economic time series. In this paper, we propose new unit root tests when a time series has multiple shifts in its level and the corresponding volatility. The proposed tests are Lagrangian multiplier type tests based on the residual's marginal likelihood which is free from the nuisance mean parameters. The limiting null distributions of the proposed tests are the χ2distributions, and are affected not by the size and the location of breaks but only by the number of breaks.

We set the structural breaks under both the null and the alternative hypotheses to relieve a possible vagueness in interpreting test results in empirical work. The null hypothesis implies a unit root process with level shifts and the alternative connotes a stationary process with level shifts. The Monte Carlo simulation shows that our tests are locally more powerful than the OLSE-based tests, and that the powers of our tests, in a fixed time span, remain stable regardless the number of breaks. In our application, we employ the data which are analyzed by Perron (1990), and some results differ from those of Perron's (1990).  相似文献   

8.
公众科学知识素养的缺乏,社会功能的分工及科技民主价值观念的形成,决定了专家参与危机管理的必要性。中国危机管理面临着突出的专家信任失灵问题。公众对专家知识期望的理想化、专家自身知识的价值偏向、专家参与机制有效性无法保证、信息公开透明度不够等,从知识论层面与现实层面构成了信任失灵的根源。构建专家信息库、提高言论被“收买”的风险成本、完善良好的沟通机制是重获专家信任权威的有效策略。  相似文献   
9.
明朝末年李自成领导农民起义,经过15年的艰苦奋斗,推翻了腐败的明王朝,建立了"大顺"农民政权,但是仅仅42天就丢了江山。其中原因值得探究。马克思主义认为,内因决定事物的性质和发展方向。深层次地挖掘李自成起义失败的内因,有助于我们深刻地认识这场农民起义,并以此加深对农民阶级的阶级特征与阶级属性的认识,从而丰富农民起义史的研究。  相似文献   
10.
ABSTRACT

We consider the use of modern likelihood asymptotics in the construction of confidence intervals for the parameter which determines the skewness of the distribution of the maximum/minimum of an exchangeable bivariate normal random vector. Simulation studies were conducted to investigate the accuracy of the proposed methods and to compare them to available alternatives. Accuracy is evaluated in terms of both coverage probability and expected length of the interval. We furthermore illustrate the suitability of our proposals by means of two data sets, consisting of, respectively, measurements taken on the brains of 10 mono-zygotic twins and measurements of mineral content of bones in the dominant and non-dominant arms for 25 elderly women.  相似文献   
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