Nd:GdYVO4与Nd:YVO4的激光倍频特性比较

在相同实验条件下,采用V型折叠腔对比了Nd:GdYVO4和Nd:YVO4两种晶体的腔内倍频特性。利用KTP腔内倍频,在泵浦功率为6.71W时分别获得了1.69W和1.46W的稳定倍频绿光输出,光-光转换效率分别达到25.2%和21.8%。比较得出,由于Nd:GdYVO4晶体良好的导热性,在大功率激光泵浦条件下,Nd:GdYVO4/KTP获得了更好的倍频激光输出。     

“五四”前后北京大学世界语传播概述

世界语(Esperanto)清末传入中国,但真正在中国得到推广却是在“五四”新文化运动时期。北京大学作为新文化运动及“五四”运动的摇篮,对于世界语这种外来语进行了不遗余力的宣传推广,并走出校园,到民众中进行宣传,从而为世界语运动在中国的开展奠定了基础。“五四”新知识分子的世界主义观念则是世界语在中国得以大力推广并形成社会运动的思想基础。     

大学英语四级统考效应浅析

大学英语四级考试是大学英语教学过程中的辅助手段，它会对大学英语教学起着积极有益的促进作用和消极有害的反拨作用。从四级考试效应分析中，我们发现考生的四级考试成绩与他们时真实水平不相符。我们要充分利用考试的积极效应来改进大学英语的教学方式、提高我们的大学英语教学水平。     

Gaussian models for degradation processes-part I: Methods for the analysis of biomarker data

We present two stochastic models that describe the relationship between biomarker process values at random time points, event times, and a vector of covariates. In both models the biomarker processes are degradation processes that represent the decay of systems over time. In the first model the biomarker process is a Wiener process whose drift is a function of the covariate vector. In the second model the biomarker process is taken to be the difference between a stationary Gaussian process and a time drift whose drift parameter is a function of the covariates. For both models we present statistical methods for estimation of the regression coefficients. The first model is useful for predicting the residual time from study entry to the time a critical boundary is reached while the second model is useful for predicting the latency time from the infection until the time the presence of the infection is detected. We present our methods principally in the context of conducting inference in a population of HIV infected individuals.     

五四时期马克思主义传播历史特点平议

五四时期马克思主义传播有三个突出特点 :不是没有真理性的强意识形态化 ,而是具有符合中国反帝反封建斗争需要的彻底革命性 ,是马克思主义作为真正揭示中国革命规律的思想武器被中国人民接受 ;不是对外排斥一切文化、对内拒绝自我更新 ,而是具有科学的开放性 ,对外积极吸收其他文化优秀成分 ,对内不断自我更新 ;不是排斥知识分子 ,也不是强迫知识分子向落后的农民认同 ,而是具有主体的大众性 ,以具有初步共产主义思想的知识分子为桥梁 ,迅速与工人运动相结合并影响农民运动 ,从而实现了以中国人民为实践主体。     

The Double Gaussian Approximation for High Frequency Data

Abstract High frequency data have become an important feature of many areas of research. They permit the creation of estimators in highly non‐parametric classes of continuous‐time models. In the context of continuous semi‐martingale models, we here provide a locally parametric ‘double Gaussian’ approximation, to facilitate the analysis of estimators. As in Mykland and Zhang (Econometrica, 77, 2009, p. 1403), the error in the approximation can be offset with a postasymptotic likelihood correction. The current approximation is valid in large neighbourhoods, permitting a sharp analysis of estimators that use local behaviour over asymptotically increasing numbers of observations.     

Multivariate τ-estimators for location and scatter

We discuss the robustness and asymptotic behaviour of τ-estimators for multivariate location and scatter. We show that τ-estimators correspond to multivariate M-estimators defined by a weighted average of redescending ψ-functions, where the weights are adaptive. We prove consistency and asymptotic normality under weak assumptions on the underlying distribution, show that τ-estimators have a high breakdown point, and obtain the influence function at general distributions. In the special case of a location-scatter family, τ-estimators are asymptotically equivalent to multivariate S-estimators defined by means of a weighted ψ-function. This enables us to combine a high breakdown point and bounded influence with good asymptotic efficiency for the location and covariance estimator.     

培养创造性的4Ps模式在市场营销教学中的应用

美国的市场营销信息系统专家 J.D.Couger和 T.M.Ambile等人提出了培养创造性的观念、方法和手段 ,可以设计为总体的 4Ps模式 ,包括对于创造性的理解和创造技法的运用。这一体系应用在市场营销专业的教学上收到了良好的效果 ,它可以进一步应用于管理培训     

基于MPEG-4的三维人脸动画

具有真实感的三维人脸动画是计算机图形学研究的一个重要分支,有着广泛的应用领域。如何在三维人脸模型上实时地模拟人脸的运动,产生具有真实感的人脸表情和动作,是其中的一个难点。该文在MPEG-4的三维人脸动画原理的基础上提出一种新的基于MPEG-4的、适宜于任意拓扑结构模型的三维人脸动画实现方法。该方法能够在FAP帧的驱动下实现真实感较强的三维人脸动画。     

加速发展我国4PL的对策建议

供应链物流的发展历程（传统自营物流→功能性外包物流→现代3PL→4PL）显然4PL物流已经来临。4PL在国内外的研究都仍处于起步阶段，本论文在阐述4PL的内涵及其优点的基础上，阐述了4PL在我国的应用现状，并结合我国的实际提出了