等位面示教板

实验示教板将固定低频振荡器(约700赫)和低频放大器、喇叭、合装入一匣内,以便易于安装携带。做长探针一对,用三合板做示教板一块,面积一米见方。将绒布、两金属电极(内电极由圆形薄铜板做成,外电极由铝质环状薄     

夹心压电换能器的优化设计──分析各参数对换能器性能的影响

本文给出了夹心换能器各种性能参量的表达式，较全面地分析了夹心换能器的结构与材料参数对其性能的影响，提出了在不同应用中设计该种换能器的途径。     

投影横波演示仪

一、构造及制作方法:1.木箱:尺寸大小如图1所示。木箱质料用三合板或五合板都可,它既平整,而且又比较轻便。在木箱裹面可用较粗的木条撑牢,因为三合板不易钉牢,日子久了还会弯曲。木箱内部用墨汁涂黑。在木箱靠近前端装一块毛玻璃。在木箱后面的一块板的一边钉上铰链做成活动的,在这块板中央装上小电珠的灯座,旁边装上电键及通电流的接线柱。小电珠用6—8伏     

简讯

日本Sony(即)电器公司把阳极、阴极、引线、绝缘等都印刷在同一平板上,作成夹心式多位显示板,取名叫Planitron(取意平面管——译注)。它实际上是由一片玻璃底板和与之封接的另一玻璃板组成,底板上制备有厚膜集成线路。 把一块印刷线路板和另一块璃玻板叠封起来,本来不是常见电子管的样子,但是该公司却用这种结构来制造一种新型的多位辉光显示平面板。一般辉光显示管中,在数字迭层或笔     

矩形三合板的稳定问题

一.引言 矩形三合板的稳定问题为高速飞机结构设针中经常遇到的实验问题,本文根据[1]所得的一般方程配合边界条件以求解。文中处理在一个方向受有均匀分布载荷、四边简支的矩形板及两边简支两边自由的矩形板,在形变初起的情况下若仅求临界载荷以供设计用则方程可以考虑作为線性,因之可以藉双三角函     

不同厚度有耗左手材料板中的电磁波研究

 基于有损耗的Lorentz模型的时域有限差分（FDTD）方法，模拟了有耗左手材料（LHM）平板对波源的图像聚焦特性。分别计算了不同宽度的左手材料平板结构。通过比较说明电磁波在不同厚度左手材料板中传播方式相同。材料板越薄，其聚焦点的位置越往板边缘靠近。当左手材料板的厚度不满足聚焦尺寸时，该聚焦点将会消失。     

光学测试 材料光学性能测试与设备

TB96 2006065383一种简便的测量薄透明体折射率的方法=A simple meas- urement method of refractive index of thin transparent ma- terials[刊,中]/曾勃(电子科技大学物理电子学院,四川,成都(610054)),黄子强…//光电子技术与信息．—2006,19(3)．—34-37提出了一种比较巧而简便的测量薄透明体的折射率的方法,即利用同一个楔形盒装入两种样品,一为待测样品,另一为易测折射率的透明液体参照物,将楔形盒置于迈克尔逊干涉仪光路中。利用对比,可较大地简化步骤,减少烦杂计算,较快地得到良好结果。用此方法测量了某聚合物分散液晶的折射率,与用其他方法得到的结果相符。实验表明,该方法有便于操作、成本低、效率高等优点,对薄透明体或其他材料的折射率测量具有一定的参考实用价值。图2表1参17(严寒)     

向列型液晶的定向振荡

交流电场能产生向列型液晶的定向振荡。在薄的夹心屏中观察到这种振荡,它可能由于参数激励引起(不直接借助外加激励,而依靠本身某一参数的变化取得激励。——译注)。它与一种强电光效应有关,这种效应类似于动态散射,不过具有较快的下降时间(<5ms)。     

介绍两则用自制装置做的实验

介绍两则用自制装置做的实验蒲江（四川巴中市顶山中学６３５５０６）一、自制手拉七色板目的七色光按一定比例混合，可得白光．器材一块圆薄木板（纤维板或三合板均可）、少量红、橙、黄、绿、蓝、青、紫七种颜色的颜料（或纸），一根粗线．制作（１）将圆木板按照红４５...     

夹心复合PZT材料及其应用

本文主要描述致密-多孔-致密夹心复合PZT材料及其在窄脉冲超声换能器方面的应用。通过两类六种不同夹心复合材料的换能器实验表明,未充硅橡胶的夹心复合材料是一种制作窄脉冲超声换能器的新型换能材料。     

Vehicle-passenger-structure interaction of uniform bridges traversed by moving vehicles

An investigation into the dynamics of vehicle-occupant-structure-induced vibration of bridges traversed by moving vehicles is presented. The vehicle including the driver and passengers is modelled as a half-car planar model with six degrees-of-freedom, and the bridge is assumed to obey the Euler-Bernoulli beam theory with arbitrary conventional boundary conditions. Due to the continuously moving location of the variable loads on the bridge, the governing differential equations become rather complicated. The numerical simulations presented here are for the case of vehicle travelling at a constant speed on a uniform bridge with simply supported end conditions. The relationship between the bridge vibration characteristics and the vehicle speed is rendered, which yields into a search for a particular speed that determines the maximum values of the dynamic deflection and the bending moment of the bridge. Results at different vehicle speeds demonstrate that the maximum dynamic deflection occurs at the vicinity of the bridge mid-span, while the maximum bending moment occurs at ±20% of the mid-span point. It is shown that one can find a critical speed at which the maximum values of the bridge dynamic deflection and the bending moment attain their global maxima.     

Bending and springback theory of metal-polymer sandwich laminates

In this report an analysis is made of the behavior of sandwich beams in which the core polymer is laminated on both sides with surface metal sheets, each of which has a different thickness and mechanical properties when they are loaded with a uniform bending moment which is then released resulting in springback of the bent sandwich beam. It is assumed that the polymer behaves elastically because the bending strain in the core is small and its elastic limit is much larger than that of metals. Sandwich beams have various elastoplstic stess distributions when bent depending on the mutual relationships between their dimensions, the mechanical moduli, and the applied bending moment. Further, residual curvatures, shifting position of neutral axis, and residual stress distributions in sandwich beams variously elastoplastically stressed initially on the decrease of applied bending moment are analyzed.     

偏芯光纤弯曲特性分析

根据光纤传输理论建立了偏芯光纤理论计算模型.采用保角变换方法将偏芯光纤不对称的三层结构转换成同轴对称的三层结构,得到关于传播常量的特征方程,给出了偏芯光纤弯曲损耗公式.仿真分析了偏芯光纤弯曲损耗和弯曲半径之间的关系,结果表明当弯曲半径达到3mm时,弯曲损耗几乎为零,同时得到弯曲损耗随偏芯距离的变化关系.运用Rsoft软件中的BeamPROP模块建立偏芯光纤弯曲的光学模型,模拟仿真了弯曲的偏芯光纤中模场分布情况.仿真结果表明,偏芯光纤的弯曲方向与纤芯偏移中心轴线方向相同的弯曲损耗小于反方向的弯曲损耗.     

Free vibration analysis of continuous rectangular plates

Vibration characteristics of rectangular plates continuous over full range line supports or partial line supports have been studied by using a discrete method. Concentrated loads with Heaviside unit functions and Dirac delta functions are used to simulate the line supports. The fundamental differential equations are established for the bending problem of the continuous plate. By transforming these differential equations into integral equations and using the trapezoidal rule of the approximate numerical integration, the solution of these equations is obtained. Green function which is the solution of deflection of the bending problem of plate is used to obtain the characteristic equation of the free vibration. The effects of the line support, the variable thickness and aspect ratio on the frequencies and mode shapes are considered. By comparing the numerical results obtained by the present method with those previously published, the efficiency and accuracy of the present method are investigated.     

Static and Dynamic Analyses of Spliced Column

The analysis of spliced column has been carried out to detect optimum location of providing splices in the column. In the present work, static and dynamic (free vibration) analyses of spliced column have been done by randomising the location of splicing. A symmetrical four storey steel framed building has been modelled, analysed and designed for loads (dead, live and earthquake loads) recommended by Indian Codal provisions using Staad.Pro. The critical column at each floor level is identified based on axial force (AF), bending moment (BM) and shear force (SF). The total 16 models of spliced columns have been designed and then modelled in a 3D CAD Design tool (SOLIDWORKS) and then imported in the finite element tool (ANSYS Workbench 14.0) for detailed analysis. The variation of stress, strain and deflection of the spliced column are shown in the form of contour. Further, the modal analysis is performed to determine the natural frequencies. The results of static and dynamic analyses are compared for each modelled spliced column to obtain the optimum location for providing splices in the column. The dynamic analysis of spliced column is of utmost importance in the region where dynamic loadings like earthquake, cyclones etc. are more frequent, and mere static analysis does not account for the safety of the structure. This study will help the engineers to select directly the optimum size and location of the splices in the column of a steel framed building.     

一边平夾另一边受均布力矩作用的环形薄板大挠度问题

一.引言 作者曾在文献中指出,用摄动法来处理在均布边缘力矩作用之下的弹性圆薄板大挠度问题,不但远较用数字积分法来得简便,而且还提供了最大挠度以及应力的设计公式,使它们能直接应用到工程设计问题上去。本文则引申之,同样成功地处理了另一些具有实用价值但一直还未被研究过的问题,即外(内)边平夹,而沿内(外)边有均布边缘力矩作用的环形薄板大挠度问题。     

光纤光栅称重传感器研究

提出一种基于光纤光栅传感技术的称重系统.用特种粘贴剂将布喇格光纤光栅(FBG)粘贴于悬臂梁的自由端,当悬臂梁自由端受力发生微挠度弯曲时,光纤光栅将沿轴向发生形变,通过监测布喇格光纤光栅传感器反射波长漂移测量悬臂梁的微挠度变化.通过分析悬臂梁结构,建立悬臂梁受力与挠度的数学关系,进而测量出加载在悬臂梁自由端应力的数值.通过对系统结构理论分析和实验验证,该装置称重测量范围达到50千克力,测量灵敏度达到0.05千克力,线性拟合度达到0.9997.     

A SEMI-ANALYTICAL APPROACH TO THE NON-LINEAR DYNAMIC RESPONSE PROBLEM OF BEAMS AT LARGE VIBRATION AMPLITUDES, PART II: MULTIMODE APPROACH TO THE STEADY STATE FORCED PERIODIC RESPONSE

The semi-analytical approach to the non-linear dynamic response of beams based on multimode analysis has been presented in Part I of this series of papers (Azrar et al., 1999 Journal of Sound and Vibration224, 183-207 [1]). The mathematical formulation of the problem and single mode analysis have been studied. The objective of this paper is to take advantage of applying this semi-analytical approach to the large amplitude forced vibrations of beams. Various types of excitation forces such as harmonic distributed and concentrated loads are considered. The governing equation of motion is obtained and can be considered as a multi-dimensional form of the Duffing equation. Using the harmonic balance method, the equation of motion is converted into non-linear algebraic form. Techniques of solution based on iterative-incremental procedures are presented. The non-linear frequency and the non-linear modes are determined at large amplitudes of vibration. The basic function contribution coefficients to the displacement response for various beam boundary conditions are calculated. The percentage of participation for each mode in the response is presented in order to appraise the relation to higher modes contributing to the solution. Also, the percentage contributions of the higher modes to the bending moment near to the clamps are given, in order to determine accurately the error introduced in the non-linear bending stress estimated by different approximations. Solutions obtained in the jump phenomena region have been determined by a careful selection of the initial iteration at each frequency. The non-linear deflection shapes in various regions of the solution, the corresponding axial force ratios and the bending moments are presented in order to follow the behaviour of the beam at large vibration amplitudes. The numerical results obtained here for the non-linear forced response are compared with those from the linear theory, with available non-linear results, based on various approaches, and with the single mode analysis.     

光折变明孤子的自偏转演化特性

利用一维稳态光折变空间光孤子的统一理论，研究了负载电阻对屏蔽、光伏和屏蔽光伏明孤子自偏转特性的影响。结果表明，无论加载电阻与否，这三种类型的光折变明孤子具有类似的自偏转特性，即孤子波沿一个抛物线轨迹运动。调节负载电阻可以改变孤子的偏转幅度，其中屏蔽光伏明孤子的可调范围最大。     

Deflection in higher-order gravitational lensing

The deflection of light rays by rotating gravitational lens is considered in the framework of higher-order gravitational theory. The bending angle of light is derived. The effect of the massive scalar and tensor components of higher-order gravitational field as well as the gravito-magnetic on light deflection are discussed.