渐变折射率光波导模场分布的矢量FD-TD法分析

用二维矢量时域有限差分法分析了渐变折射率光波导中基模的模场分布情况，采用平面光波，球面光波，高斯光波等五种不同形态的光波激励同一波导，借助计算机进行数值求解，得到的光场分布图在光场传播达到稳定后完全相同，说明了波导的模式与光波形态无关，只与波导结构和光波波长有关，结果直观，精确，快速，并与解析法分析的结果相一致。     

Parametric empirical Bayes estimation of individual time-pressure reactivity

As the global workplace becomes increasingly industrialised and competitive, organisations are finding that it is crucial to manage their time more efficiently. An important topic in time management is the influence of time pressure under deadlines on individual performance. People often do less work when deadlines are far off; they then increase their work rate as deadlines approach. Although researchers have studied from various perspectives how individuals work towards deadlines, the measurement of individual differences in pacing styles has been based mostly on self-report questionnaire instruments or on frequentist estimation, which often relies on sparse data in practice. The purpose of this study is to estimate distributions of individuals’ time-pressure reactivity using a parametric empirical Bayesian estimation (PEB) approach, and to determine an adequate sample size to estimate posterior distributions. The use of PEB approach was motivated by the varied nature of sample sizes across individuals and task types. In this study, two data-sets were used, one from an online course and another from an Anti-Air Warfare Coordinator task. From these two different data-sets, we generated informative individualised posterior distributions for time-pressure activity, and the PEB approach was validated by showing the intervals of posterior distribution were smaller than the intervals of point estimates for time-pressure reactivity. In addition, we found that 18–40% of the actual number of samples was sufficient to estimate posterior distributions to within 10% error, and this finding is advantageous in cases in which collecting large sets of data may be time-consuming or expensive. This study demonstrates the effectiveness of Bayesian estimation in determining individual differences in time-pressure reactivity to deadlines using individualised posterior distributions rather than point estimates, which is beneficial for understanding differences in behaviour across a diverse population.     

Tables for a Treatments Versus Control Multiple Comparisons Sign Test

Tables are presented for a multiple comparisons sign test comparing each treatment with a control. An illustration of the test procedure is provided, and the tables are also used to construct non-parametric joint confidence intervals. It is also shown how t.o find the per-comparison error rate for a given experimentwise error rate and vice versa.     

Some Percentile Estimators for Weibull Parameters

A percentile estimator for the shape parameter of the Weibull distribution, based on the 17th and 97th sample percentiles, is proposed which is asymptotically about 66% efficient when compared with the MLE (maximum likelihood estimator). A two-observation percentile estimator, based on the 40th and 82nd sample percentiles, for the scale parameter when the shape parameter is unknown is asymptotically about 82y0 efficient when compared with the MLE. The 24th and 93rd sample percentiles yield asymptotically about 41ye jointly efficient percentile estimators for both the scale and shape parameters in a class of two-observation percentile estimators when compared with their MLEs. Some other simple percentile estimators for these parameters are also briefly discussed. Finally, asymptotic properties of these estimators are investigated and their application in statistical inference problems is mentioned.     

Univariate and multivariate process yield indices based on location-scale family of distributions

Several measures of process yield, defined on univariate and multivariate normal process characteristics, have been introduced and studied by several authors. These measures supplement several well-known Process Capacity Indices (PCI) used widely in assessing the quality of products before being released into the marketplace. In this paper, we generalise these yield indices to the location-scale family of distributions which includes the normal distribution as one of its member. One of the key contributions of this paper is to demonstrate that under appropriate conditions, these indices converge in distribution to a normal distribution. Several numerical examples will be used to illustrate our procedures and show how they can be applied to perform statistical inferences on process capability.     

Signal detection theory with finite mixture distributions: Theoretical developments with applications to recognition memory.

An extension of signal detection theory (SDT) that incorporates mixtures of the underlying distributions is presented. The mixtures can be motivated by the idea that a presentation of a signal shifts the location of an underlying distribution only if the observer is attending to the signal; otherwise, the distribution is not shifted or is only partially shifted. Thus, trials with a signal presentation consist of a mixture of 2 (or more) latent classes of trials. Mixture SDT provides a general theoretical framework that offers a new perspective on a number of findings. For example, mixture SDT offers an alternative to the unequal variance signal detection model; it can also account for nonlinear normal receiver operating characteristic curves, as found in recent research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temporal Control of Conditioned Responding in Goldfish.

The peak procedure was used to characterize response timing during acquisition and maintenance of conditioned responding in goldfish. Subjects received light-shock pairings with a 5- or 15-s interstimulus interval. On interspersed peak trials, the conditioned stimulus light was presented for 45 s and no shock was delivered. Peaks in the conditioned response, general activity, occurred at about the time of the expected unconditioned stimulus, and variability in the activity distribution was scalar. Modeling of the changes in the activity distributions over sessions revealed that the temporal features of the conditioned response changed very little during acquisition. The data suggest that times are learned early in training, and, contrary to I. P. Pavlov's (1927/1960) concept of "inhibition of delay," that timing is learning when to respond rather than learning when not to respond. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

太赫兹雷达直升机旋翼目标微动特性研究

直升机旋翼微动形成的微多普勒特征对于战场环境下直升机目标探测识别具有重要意义,掌握直升机旋翼的微动特性是雷达目标辨识的前提。太赫兹雷达波长短,多普勒效应显著,迫切需要掌握太赫兹频段旋翼目标微动特性。首先对偶数叶片和奇数叶片的螺旋桨目标进行建模,分别使用微波波段(3 GHz)与太赫兹波段(120 GHz,220 GHz)雷达对目标进行仿真分析,并从目标的回波信号特征出发提取多普勒频移信息,利用短时傅里叶变换进行时频分析,对比分析目标与雷达参数对其多普勒效应的影响及调制关系。仿真结果表明：在转速、视角以及直升机叶片长度均相同的情况下,太赫兹频段下的微多普勒效应比微波频段显著增强,多普勒曲线也更加清晰,叶片细节更加丰富。应用太赫兹雷达提取微多普勒信息能够为直升机目标识别提供重要特征。     

一种求解超越方程零极点分布的谐波不稳定分析方法

考虑线路分布参数模型是准确分析风电场谐波不稳定的必要条件,但模型的引入导致谐波不稳定分析面临系统超越方程零极点分布难以求解的问题。基于此,文中首先建立并验证考虑线路分布参数的风电场阻抗模型。其次,提出一种基于Pade近似的超越方程零极点分布求解方法,将指数函数近似为有理分式,仅须选择有理分式阶次,而无须拟合系数。然后,分析不同线路长度和电网强度下,不同线路模型对系统谐波不稳定影响。最后,通过仿真验证所提方法的有效性和准确性。结果表明：线路分布参数不可被忽略,否则将可能导致稳定性和高频谐波放大点分析不准确,甚至遗漏高频谐波放大点。文中所提方法不仅可准确评估系统的稳定性,还可分析系统的谐波放大点。