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51.
针对传统达里厄( Darrieus)直叶片垂直轴风力机在运行过程中出现叶片动转矩周期波动性大,动转矩系数曲线
震荡剧烈,造成对风轮旋转主轴的强烈冲击及风力机功率输出不稳定等问题,文章提出对Darrieus垂直轴风力机传统直
叶片进行螺旋扭曲变异设计,以改善风力机叶片的动转矩输出性能。结合SolidWorks和MATLAB完成风力机模型的三
维参数化建模,在流体仿真软件FLUENT中完成模型的数值模拟仿真计算。通过螺旋扭曲角的单因素试验验证了变异
设计叶片输出的动转矩性能周期波动性降低,平均动转矩得到提高,并确定螺旋扭曲角的优化区间。文章构建了风力机
系统模型建立与仿真体系,采取螺旋扭曲变异设计,改善了风力机叶片输出的动转矩性能,初步确定合理的螺旋扭曲角
分布范围为:70°~ ll0°。 相似文献
52.
53.
The monetary policy targets the short rates; however, during zero interest rate policy (ZIRP), the short end of the yield curve cannot serve as a policy instrument. Relying on the joint yields-macro latent factors model, this study empirically examines the effect of monetary policy stances on term structure and the possible feedback effect on the real sector using the Japanese experience of ZIRP. The analysis indicates that it is the entire term structure that transmits the policy shocks to the real economy rather than the yield spread only. The monetary policy signals pass through the yield curve level and slope factors to stimulate the economic activity. The curvature factor, besides reflecting the cyclical fluctuations of the economy, acts as a leading indicator for future inflation. In addition, policy influence tends to be low as the short end becomes segmented toward medium/long-term of the yield curve. Furthermore, volatility in bond markets is found to be asymmetrically affected by positive and negative shocks and long end tends to be less sensitive to stochastic shocks than the short maturities. The expectation hypothesis of the term structure does not hold during the ZIRP period. 相似文献
54.
航位推算系统非线性过程处理新方法研究 总被引:1,自引:0,他引:1
针对航位推算系统中利用扩展Kalman滤波方法解决非线性问题在算法复杂性上的缺陷和精度上的不稳定性,该文从数据预先处理的角度出发,合理规避线性化过程,提出一种充分利用现成Kalman滤波公式的方法,即数据进入滤波器之前就预先进行处理,获得每一组量测值,按照极坐标-笛卡儿坐标的转换方式转为相应的位置信息,再按照标准的Kalman滤波公式构建滤波器,进行状态的最优估计。计算机仿真结果证明该算法的有效性。 相似文献
55.
As the first quantitative examination of perceived public relations professional standards in China using an online survey, this study was designed based on the standards of professional standards inventory Cameron, Sallot, & Lariscy (1996) constructed and tested among practitioners in the U.S. The survey results suggest six dimensions of perceived standards of professional performance: (1) role and function in organizational strategic planning, (2) sufficiency in professional training and preparedness, (3) gender and racial equity, (4) situational constraints, (5) licensing and organizational support, and (6) participation in the organizational decision-making team. Four dimensions of public relations roles were also identified by the survey participants: (1) brand promotion facilitator, (2) public information specialist, (3) media relations counsel, and (4) conflict management expert. Primary practice area was found to affect how Chinese practitioners perceive the six clusters of professional standards and the four identified public relations roles. These findings provide insights for both practitioners and researchers on how Chinese public relations practitioners view public relations as a profession and how the profession currently holds its professional standards in China. 相似文献
56.
Alberto Luceño 《统计学通讯:模拟与计算》2013,42(1):235-245
A well-know process capability index is slightly modified in this article to provide a new measure of process capability which takes account of the process location and variability, and for which point estimator and confidence intervals do exist that are insensitive to departures from the assumption of normal variability. Two examples of applications based on real data are presented. 相似文献
57.
孙忻 《河南工业大学学报(社会科学版)》2012,8(4):10-15
实现主食产业化发展,实行产品的标准化是关键。以豪特林(Hotelling)线形选址模型和塞洛普(Salop)的圆周模型为基础,根据具体情况进行修改后建立一个三阶段的博弈模型讨论主食企业和政府的行为问题。 相似文献
58.
《Journal of Statistical Computation and Simulation》2012,82(12):1939-1969
Uncertainty and sensitivity analysis is an essential ingredient of model development and applications. For many uncertainty and sensitivity analysis techniques, sensitivity indices are calculated based on a relatively large sample to measure the importance of parameters in their contributions to uncertainties in model outputs. To statistically compare their importance, it is necessary that uncertainty and sensitivity analysis techniques provide standard errors of estimated sensitivity indices. In this paper, a delta method is used to analytically approximate standard errors of estimated sensitivity indices for a popular sensitivity analysis method, the Fourier amplitude sensitivity test (FAST). Standard errors estimated based on the delta method were compared with those estimated based on 20 sample replicates. We found that the delta method can provide a good approximation for the standard errors of both first-order and higher-order sensitivity indices. Finally, based on the standard error approximation, we also proposed a method to determine a minimum sample size to achieve the desired estimation precision for a specified sensitivity index. The standard error estimation method presented in this paper can make the FAST analysis computationally much more efficient for complex models. 相似文献
59.
伴随着国际体育运动商业化的进程,兴奋剂成为困扰国际体育领域的重大问题。为减轻兴奋剂处罚体系多重性给运动员造成的负担,在国际奥委会的推动下,国际社会正进行着兴奋剂处罚体系统一化的努力。在这一进程中,应关注对运动员正当程序利益的保护,发挥国际仲裁院对个案的裁决及评价作用,推动各体育组织间的配合,使兴奋剂处罚体系更趋合理及法律化。 相似文献
60.
储层非均质性研究是油田开发后期剩余油挖潜、提高采收率的关键。以河流沉积学理论为指导、以现代沉积、露头调查为依据,利用密井网条件下丰富的测井资料和储层建筑结构层次分析方法对孤岛油田馆陶组上段储层进行了研究。研究认为,孤岛油田馆陶组上段储层可划分为十个层次,并将储层精细解剖到第七层次,识别出主河道、废弃河道、决口水道等七种建筑结构要素。在储层精细对比的基础上,总结出以单一河道砂体追溯为核心建立单砂体建筑结构模型的方法,并探讨了这种地质结构模型对于油田开发挖潜的重要意义。 相似文献