试论明清大运河上的行船次序

运河开凿与管理的主要目的在漕运,但在实际运行过程中,贡鲜船是运河上的特权船只,漕船次之,然后是官船和军民船,商贾船地位最低.运河行船次序反映了不同船只的政治地位,折射出漕河管理的诸多弊端.特权船只优先使用有限的交通资源,是皇权观念在河道管理中的缩影,不利于商品的顺畅流通与社会经济的健康发展.     

基于正交分析的双面组合连续箱梁剪力滞效应影响因素研究

考虑宽跨比、截面高度、翼缘板外伸长度、荷载类型等影响剪力滞效应的主要因素,采用正交分析方法对钢 混凝土双面组合连续箱梁进行试验设计,对设计工况进行数值仿真试验,并对计算结果进行正交分析。研究结果表明,荷载形式对双面组合箱梁剪力滞系数的影响最大,宽跨比的影响次之,而截面几何尺寸的因素如截面高度和翼缘板外伸长度在工程实用范围内的影响很小。通过统计回归,得到了弹性阶段钢 混凝土双面组合连续箱梁上翼缘有效宽度的无量纲计算公式。     

Optimal bayesian confidence interval of fixed width

We obtain the optimal fixed width Bayes confidence interval (optimal in the sense that the posterior probability of 8 being in the interval is maximum) for the parameter 6 , when the posterior distribution of ?^-1 , given the data is known to be a truncated gamma distribution.     

一类复子波的时-频局域化特征分析

介绍了一类新的复基子波??Y(母波,引进时间算子和频率算子分析了Y(母波的时间、频率和时－频局域化特征。理论和数值分析结果表明：Y(母波具有良好的时(频局域化特征;选择适当的参变量,可以构造出逼近“最优”时－频局域化特征窗函数的复母波。     

Empirical Bayes vs. fully Bayes variable selection

For the problem of variable selection for the normal linear model, fixed penalty selection criteria such as AIC, _Cp${\mathrm{C}}_p$, BIC and RIC correspond to the posterior modes of a hierarchical Bayes model for various fixed hyperparameter settings. Adaptive selection criteria obtained by empirical Bayes estimation of the hyperparameters have been shown by George and Foster [2000. Calibration and Empirical Bayes variable selection. Biometrika 87(4), 731–747] to improve on these fixed selection criteria. In this paper, we study the potential of alternative fully Bayes methods, which instead margin out the hyperparameters with respect to prior distributions. Several structured prior formulations are considered for which fully Bayes selection and estimation methods are obtained. Analytical and simulation comparisons with empirical Bayes counterparts are studied.     

Familles of confidence bands for the survival function under the general random censorship model and the Koziol-Green model

Familles of asymptotic 100(1 – α)% level confidence bands for the survival function under the general random right-censorship (GRC) model and the proportional-hazards model of random right-censorship, also known as the Koziol-Green (KG) model, are developed. The family of bands under the GRC model is based on the well-known product-limit estimator (PLE), and this family is rich in that it contains as special cases the bands of Hall and Wellner (1980) and Gillespie and Fisher (1979), and more generally, the GF-type and HW-type bands of Csörg? and Horváth (1986), as well as new bands not previously studied. The familles of bands under the KG model are based on the maximum-likelihood estimator of F under this particular model. We compare the PLE-based bands and the MLE-based bands under the KG model. This enables us to study the loss in efficiency of the former bands when used in a setting where they are not optimal. The notion of asymptotic relative width efficiency (ARWE), defined to be the limiting ratio of the sample sizes needed by the bands to achieve the same asymptotic widths, is employed to compare two bands. Through this efficiency measure it is shown that if the censoring parameter β is known, then the PLE-based bands are highly inefficient relative to the MLE-based bands when β is large. When β is not known, the MLE-based bands are asymptotically conservative. Despite their conservatism, they still dominate the PLE-based bands when β is not too small or equivalently when the degree of censoring is not too light. We also compare the various PLE-based bands under the GRC model. The resulting information is valuable for evaluating competing PLE-based bands. We illustrate the confidence bands by utilizing the well-known Channing House data.     

关于具有常数带宽的凸闭曲线的一个附注

本文举例说明具有常数带宽的凸闭曲线不一定是圆。     

浅论一维透射光栅的性能

本文对一维透射光栅话线的衍射角、强度、谱线宽度、色散率、分辩本领等方面的决定因素和性能特点进行了论证。     

平衡二元性与企业绩效关系再研究

探索和利用二元平衡是企业重要的战略选择.然而,理论界对平衡二元性与企业绩效关系的研究呈现出相悖的结论.文章尝试通过平衡二元性的维度细化和作用情境引入两条路径消除已有研究的悖论:一方面,通过区分高能平衡和低能平衡,发现高能平衡促进企业绩效而低能平衡对企业绩效存在负面影响;另一方面,引入种群生态理论“生态位选择”的观点,考察环境动荡性的情境调节效应,发现环境动荡程度(市场环境和技术环境)对平衡二元性与企业绩效关系存在显著的负向调节作用.研究结论说明低能平衡并不能带来绩效的显著提升,而且在高度动荡的环境中,二元平衡(通才策略)并不利于提高企业绩效,反而是偏才(专注于探索或利用)致胜.研究结论对于商业生态竞争趋势下的企业战略选择具有重要启示意义.     

脉宽调制（PWM）型300W开关稳压电源的研制

本文介绍笔者研制的脉宽调制（PWM）300W开关稳压电压的电路，原理及部分电路的设计、调度方法，该机具有输出电流大、成本低、实用性强的特点。