基于负反馈理论的半导体激光器驱动器的设计与仿真实验研究

本文设计出了一种实用的大功率半导体激光器驱动器,它可提供恒流和恒功率两种驱动方式,采用深度负反馈控制原理实现稳定控制。重点介绍了恒流驱动电路原理,并应用Multisim7进行软件仿真实验研究。在此基础上还设计了保护电路。     

C2C网上交易中信号机制的有效性分析

本文应用Berry等(1995)^[2]提出的离散选择需求模型和差异产品的伯川德竞争模型,并利用淘宝网上的交易数据,对声誉、消费者保障计划、保修服务及信息披露四种信号策略在网上交易中的作用进行了实证研究。需求估计结果表明消费者保障计划中的"7天无理由退换货"计划以及保修服务可以作为产品质量的信号;而在其他有效信号策略存在的情况下,消费者保障计划中的"先行赔付"计划以及卖家声誉作为质量信号的作用则被削弱。成本分析表明,信息披露虽然可以提高消费者购买的可能性,但是由于发出信号的成本太低,容易被低质量卖家所模仿,因此并不能作为有效的质量信号。本文首次从供给和需求两个方面分析了信号机制在信息不对称情况下的效应及其作用机制。     

Phase I monitoring and change point estimation of autocorrelated poisson regression profiles

The objective of this paper is to study the Phase I monitoring and change point estimation of autocorrelated Poisson profiles where the response values within each profile are autocorrelated. Two charts, the SLRT and the Hotelling's T², are proposed along with an algorithm for parameter estimation. The detecting power of the proposed charts is compared using simulations in terms of the signal probability criterion. The performance of the SLRT method in estimating the change point in the regression parameters is also evaluated. Moreover, a real data example is presented to illustrate the application of the methods.     

Evaluating Probabilistic Forecasts with Bayesian Signal Detection Models

We propose the use of signal detection theory (SDT) to evaluate the performance of both probabilistic forecasting systems and individual forecasters. The main advantage of SDT is that it provides a principled way to distinguish the response from system diagnosticity, which is defined as the ability to distinguish events that occur from those that do not. There are two challenges in applying SDT to probabilistic forecasts. First, the SDT model must handle judged probabilities rather than the conventional binary decisions. Second, the model must be able to operate in the presence of sparse data generated within the context of human forecasting systems. Our approach is to specify a model of how individual forecasts are generated from underlying representations and use Bayesian inference to estimate the underlying latent parameters. Given our estimate of the underlying representations, features of the classic SDT model, such as the receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC), follow immediately. We show how our approach allows ROC curves and AUCs to be applied to individuals within a group of forecasters, estimated as a function of time, and extended to measure differences in forecastability across different domains. Among the advantages of this method is that it depends only on the ordinal properties of the probabilistic forecasts. We conclude with a brief discussion of how this approach might facilitate decision making.     

电场作用下裂缝介质单相渗流数值模拟

1.China University of Petroleum:a.School of Physics Science and Technology,b.College of Petroleum Engineering,Dongying Shandong 257061,China；2.Luning Transmit Oil Section,Pipeline Storage & Transportation Company,SINOPEC,Zoucheng Shandong 273500,China)JOURNAL OF SOUTHWEST PETROLEUM UNIVERSITY(SCIENCE & TECHNOLOGY EDITION)，VOL.31，NO.6,85-88,2009（ISSN 1674-5086，in Chinese     

Assessing direct and indirect seasonal decomposition in state space

The problem of whether seasonal decomposition should be used prior to or after aggregation of time series is quite old. We tackle the problem by using a state-space representation and the variance/covariance structure of a simplified one-component model. The variances of the estimated components in a two-series system are compared for direct and indirect approaches and also to a multivariate method. The covariance structure between the two time series is important for the relative efficiency. Indirect estimation is always best when the series are independent, but when the series or the measurement errors are negatively correlated, direct estimation may be much better in the above sense. Some covariance structures indicate that direct estimation should be used while others indicate that an indirect approach is more efficient. Signal-to-noise ratios and relative variances are used for inference.     

冲旋钻头破岩机理仿真研究

介绍了冲旋钻井中冲旋钻头与岩石互作用有限元模型的建立过程，并对冲旋钻头在冲击旋转和单纯冲击载荷作用下的破岩过程进行了计算机仿真研究，描述了冲旋钻头破岩过程，求出了相应的钻头破碎岩石的深度、体积时程关系对比曲线，揭示了冲旋钻头的破岩机理——钻头在冲旋作用下破碎岩石的过程可分为4个阶段、钻头破碎岩石深度主要取决于冲击作用而与旋转作用关系不大、破岩体积在冲旋作用下比单纯冲击载荷作用下要大一倍左右，为冲旋钻头在石油工业中的进一步推广应用提供了理论依据。     

On the improvement of one-sided S control charts

The most common charting procedure used for monitoring the variance of the distribution of a quality characteristic is the S control chart. As a Shewhart-type control chart, it is relatively insensitive in the quick detection of small and moderate shifts in process variance. The performance of the S chart can be improved by supplementing it with runs rules or by varying the sample size and the sampling interval. In this work, we introduce and study one-sided adaptive S control charts, supplemented or not with one powerful runs rule, for detecting increases or decreases in process variation. The properties of the proposed control schemes are obtained by using a Markov chain approach. Furthermore, a practical guidance for the choice of the most suitable control scheme is also provided.     

BOOST－PFC电路反馈环节的优化设计

介绍了平均电流控制ＢＯＯＳＴ─ＰＦＣ电路的原理，建立了电流环和电压环的小信号简化模型，讨论了双环反馈环节的设计原则和方法，提出最优设计的思想和数学模型，并以一种ＢＯＯＳＴ─ＰＦＣ电路为例进行优化设计，计算模拟结果显示优化后有关指标好于优化前。     

构建铁路“车站信号自动控制“课程新体系思考

"车站信号自动控制"这一传统的铁路特色专业课程,其课程体系日显陈旧,在教学中存在的问题越来越突出。构建新的课程体系,要重组传统内容、加强新技术内容、拓宽应用。新体系实现途径是:提高理论层次,拓宽知识面,突出主干内容教学、改革教学手段和方法。