液体中热晕的矩阵分析及有关新现象

对液体中热晕现象从新的角度，即矩阵光学的方法进行了处理，以热透镜为模型，建立了热晕效应的等效焦距形成发展过程的数学表达式。同时进行了部分实验以验证理论结果。成功地观察到了热晕形成发展的全部动态过程，得到了与理论计算基本一致的实验数据。在实验中，同时观测到了一些周期性的跳动现象，给出了定性的物理解释。     

Search for a majority element

A new short proof of a theorem of Saks and Werman is given about the number of weighings necessary and sufficient to determine a majority type coin among n coins of two possible weights by comparisons. A lower bound on the number of good algorithms is proved and further questions are posed about determining the majority in different weighing models.     

三维激光扫描仪在城市外立面采集成图中的应用

当前我国正进入城市化快速增长时期。如何进行旧城的更新改造和现代化建设,是当今城市化面临的重大课题,传统测绘手段在满足旧城改造设计方面体现诸多不足。本文以Trimble GX地面三维激光扫描仪为测量设备,开展城市外立面采集方面的应用,后期采用天正软件进行城市外立面图的绘制与编辑,分析并总结了采集与后处理过程中问题与误区。     

在基础梁板设计中应用塑性理论的探讨

在基础结构设计中存在误区,导致基础结构中钢筋实测应力较计算值低得多,从而浪费大量钢材．为此提出用塑性理论进行基础结构设计的观点,并对此应用作了一些分析．     

基于ANSYS的激光焊接温度场数值模拟与实验研究

为了探究钢铝2种金属材料的焊接性能,以B1500HS高强钢和6016铝合金为对象,基于ANSYS平台建立钢／铝激光平板搭接焊的三维有限元模型,进行焊接过程温度场数值模拟,采用热电偶同步测温方法测得焊接热循环曲线。将实测结果与数值模拟结果对比分析,表明吻合度较好。验证了模拟计算的准确性。     

大功率回旋管双阳极电子枪计算机辅助设计

根据回旋管对电子枪的要求,采用综合法和分析法设计了该双阳极磁控注入电子枪。编制了一套大型的计算程序;利用计算机辅助设计,给出了电极形状、电子轨迹与电子注参量。计算表明,这种电子枪具有速度零散小、层流性好、体积小等特点。该电子枪更能适应大电流工作情况,已经用于制管实验中。由热测实验表明,它具有明显的优点。     

应用激光透射信号随机波动特性求取颗粒尺寸及浓度

阐述了利用穿越介质后的激光信号的随机波动来测量颗粒尺寸和浓度的原理和方法,并在实验室条件下对标准颗粒进行了验证,实验结果表明,该方法在低颗粒浓度和较高浓度时都能得到的测量结果,建立在该原理上的测量仪器结构简单,对环境要求低,无需特殊的保护措施,这些特点为工业生产中的在线监测提供了一种有效的方法。     

李白与苏轼的创作个性之异

李白与苏轼的创作个性具有“旷放”与“旷达”的差异,前者倾向于外放热烈,后者倾向于内敛冷静。其原因在于李白是把自己摆放在繁华鼎盛的大唐帝国的横向历史背景之上来建构个人的理想,其豪侠的性格使建功立业的思想强烈伸张。苏轼更善于将自己摆放在宇宙人生的纵向历史中,着眼于调整自己与自然、与社会的关系,以求取内心的“和”与“安”的境界。     

Does age affect the efficacy and safety of GreenLight HPS™ laser photoselective vaporization prostatectomy?

Background: To evaluate the efficacy and safety of GreenLight HPS^? (High Performance System) laser photoselective vaporization prostatectomy (PVP) for the treatment of benign prostatic hyperplasia (BPH) in patients of different age groups. Methods: 164 consecutive patients were stratified into two groups: age <70 (group I, n?=?93) and age ≥70 (group II, n?=?71) years. Transurethral PVP was performed using a GreenLight HPS? side-firing laser system. Voiding parameters were measured preoperatively and at 1 and 4 weeks and 3, 6, 12, 18, 24 and 36 months postoperatively. Results: Among the preoperative parameters evaluated, there were significant differences (p?<?0.05) in prostate volume (I: 58.7; II: 73.6?mL) and serum prostate-specific antigen (I: 1.9; II: 2.9?ng/mL), while American Urological Association Symptom Score (AUASS), Quality of Life (QoL), maximum flow rate (Qmax), Sexual Health Inventory for Men (SHIM) and post void residual (PVR) were similar (p?>?0.05) between groups. No significant differences in laser utilization, energy usage and operating time were noted. Clinical outcomes (AUASS, QoL, Qmax, PVR) showed immediate and stable improvement from baseline (p?<?0.05) within each group, but no significant differences between the two groups were observed during the follow-up period. The incidence of adverse events was low and similar in both groups. Conclusions: The results suggest that age has little effect on the efficacy and safety of GreenLight HPS? laser PVP.     

W9Cr4V高速钢非光滑表面耐磨性正交设计试验研究

采用MG-2000高速高温摩擦磨损试验机,用正交设计试验方法研究凹坑形非光滑表面形态的耐磨性,选取温度、凹坑直径和凹坑间距作为试验因素,每个因素选取2个水平。试验结果表明,在本次试验条件下,温度对非光滑试样耐磨性影响最大,凹坑直径其次,凹坑间距最次,这为凹坑型非光滑表面尺寸和分布密度的选取提供了初步的试验数据。