景深公式的推导

详细说明了立体物能成平面像的原因，界定了景深近界限和景深远界限的概念，导出了景深公式。     

重点在于促进

《民办教育促进法》重点应在“促进”上，应提出强有力的促进民办教育发展的措施。其不完善处期待出台“实施条例”加以弥补。     

加工中心无报警故障诊断检修

本文阐述了加工中心参考点的检测、减速开关故障的诊断及维修步骤.修复后符合原机床的精度,可获得显著的效益.     

VLAN技术在校园网中的应用

根据校园网应用中存在的问题，提出用VLAN技术解决问题的方法，接着介绍VLAN的定义和特点，最后详细介绍VLAN技术在校园网的应用。     

Soft Switched Synchronous Rectifier with Phase-Shifted Full Bridge Converter and Its Small-Signal Analysis

BY USING THE OUTPUT INDUCTORS AND BODY CAPACITANCES WITHOUT ADDING ANY COMPONENT COMPARED WITH HARD SWITCHING SYNCHRONOUS RECTIFIER,THE TOPOLOGY OF A SOFT SWITCHED SYNCHRONOUS RECTIFIER WITH PHASE-SHIFTED FULL BRIDGE ZERO VOLTAGE SWITCHING DC/DC CONVERTER IS PROPOSED. THE CONVERTER EFFICIENCY IS MAXIMIZED DUE TO SOFT SWITCHING OF THE FULL BRIDGE MOSFETS AND THE SYNCHRONOUS MOS-FETS, AND ALSO THE LOW CONDUCTION LOSS OF SYNCHRONOUS MOSFET. THE OPERATION PRINCIPLES OF THE CIRCUIT ARE ANALYZED IN DETAIL AND THE SMALL-SIGNAL MODEL IS DERIVED, ALSO THE CONVERTER DYNAMIC CHARACTERISTICS ARE ANALYZED. FREQUENCY RESPONSES OF TRANSFER FUNCTIONS UNDER DIFFERENT VALUES OF TRANSFORMER PRIMARY LEAKAGE INDUCTANCE ARE DISCUSSED. THE EXPERIMENTAL RESULTS WERE OBTAINED FROM A 400 V INPUT AND 100 A/12 V OUTPUT DC/DC CONVERTER OPERATING AT 100 KHZ. THE RESULTS SHOW THAT THE CONVERTER EFFICIENCY IS 2% HIGHER IN RATED POWER THAN TRADITIONAL DIODE RECTIFIER.     

《从先学前班到8年级的课程焦点:追求连贯性》报告述评

在美国数学课程改革过程中,学生在国际数学测试中排名下降,教师授课存在困难.为了国家教育政策的需要,美国全国数学教师理事会公布了《课程焦点》报告.该报告列出了从幼儿园到8年级每个年级具体的数学课程焦点,是美国建构主义数学课程改革回归基础的适当转向.     

Fragility of disconnect switch subjected to random earthquake ground motions

A fragility calculation scheme is estabtished in this paper for porcelain-type equipments subjected to random earthquake ground motions. All steps of the method are illustrated by the seismic damage analysis of GW4-110 disconnect switch. The model of the equipment is built applying the finite element method with flexible joints, and the seismic response of the equipment is analyzed using elastic time history method. On the base, according to the strength damage index and Monte-Carlo Method, the seismic dama...     

LED光源在薄透镜焦距测定实验中的应用

在薄透镜焦距测定实验中,使用改装后的超亮LED(发光二极管)灯作为新的实验用光源,不仅实验效果明显优于原有白炽灯光源,而且符合节能、环保,低碳经济的要求。     

以太网交换机原理实验设计

介绍了以太网交换机的工作原理,并设计了具体的实验方案,来演示交换机维护、使用其MAC地址与端口对应表的方法。在交换机上使用displaymac-address命令,或利用交换机网管功能观察交换机中MAC地址表信息,并通过自己开发的交换机MAC地址攻击工具,演示交换机MAC地址表溢出时非法侦听的实施,以及交换机对此类攻击行为的防范措施。     

基于星型网络的片上光互连系统设计方案

提出了一种基于星型网络的片上光互连系统设计方案,并给出了16×16中心节点互连开关模型。系统以光电混合设计方式,采用SOPC技术实现中央节点对各路数据通道的互连功能。该系统具有16路双向互连通道,每通道的数据传输速率可达10 Gb/s;16路互连通道可同时独立工作,系统总的数据并行传输速率可达到160 Gb/s,可有效解决当前长距离电互连中的速率瓶颈问题。