摊铺机螺旋布料器控制系统的改进

<正>摊铺机2个螺旋布料器的作用是将混合料向左、右两侧横向摊开,然后由熨平板将混合料摊铺在地面上。螺旋布料器横向布料时,必须使熨平板前面的混合料饱满、均匀、连续、稳定,方能保证摊铺路面的平整度和密实度。本文介绍摊铺机螺旋布料器的控制原理、存在问题及改进方法。1.控制原理摊铺宽度为9.5m的摊铺机,其螺旋布料器通常采用电控液压驱动,左、右2个螺旋布料器控制原理相同。     

一种快速分光光度计光栅参数的选择

介绍了快速分光光度计的组成 ,简述了光栅单色器的能量分布及其主要指标——色散 ,根据单色器光栅能量分布和该分光光度计的光谱范围进行光栅参数选择。使用这种方法选择的光栅完全满足快速分光光度计性能指标要求。     

可见光谱区声光快速分光光度术的实验研究

提出了一种全电子调谐快速分光的可见分光光度测量方法,以硫酸铜溶液为例,进行了实验测试和分析,结果表明声光滤光器可用作分光光度测量中的分光元件,为快速分光光度测量提供了一种新方法.     

一种快速测色分光光度计

分光光度计一般用于反射样品或透射样品的光谱测量，广泛用于化学、生物学、医疗、药检、纺织、油漆、印刷、遥感等民用工业和国防工业，获得的光谱信息在现代科技中有十分重要的价值。北京理工大学研制的测色分光光度计ＣＳＬ－１０００的组成和传统的分光光度计有所不同，它无须复杂的机械光栅扫描运动机构，省去了出射狭缝。主要由光源（闪光灯）、光耦合系统、入射狭缝、分光器、光电二极管阵列探测器、电子学系统和相应的软件组     

光谱仪器及其应用的发展和展望

本文以使用最多、覆盖面最广的常规光谱仪器(紫外可见分光光度计-UVS、原子吸收分光光度计-AAS)为代表,综述了光谱仪器及其应用的发展概况;指出了常规光谱仪器的发展方向;提出了光谱仪器发展中应该打破误区、注重可靠性等重要问题。     

中子衍射应力谱仪垂直聚焦单色器的优化设计

为提高应力谱仪样品处的中子注量率,对垂直聚焦单色器进行了优化设计.应用蒙特卡罗模拟程序MCSTAS对中子衍射应力谱仪的垂直聚焦Ge(511)单色器进行优化计算,得到了垂直聚焦单色器的高度与单晶片之间的倾角等参数的最佳值.然后,对比分析了在垂直聚焦单色器与平板单色器两种情况下样品处的中子注量率.最后,讨论了单色器起飞角对谱仪分辨率的影响.计算结果表明:单色器尺寸为50 mm×150 mm;垂直单色器在样品台中心位置的中子注入量是平板单色器的4.99倍,表明利用垂直单色器可以显著提高应力谱仪样品处的中子注量率.     

北京地质仪器厂研制成功两种原子吸收分光光度计

由北京地质仪器厂研制成功的GGX-4型和GGX-5型原子吸收分光光度计,1986年9月在北京通过鉴定。GGX-4型原子吸收分光光度计采用永久磁铁塞曼效应背景校正器及石墨炉原子化器,为无火焰式结构。整机在微型计算机控     

721型分光光度计故障检修

７２１型分光光度计故障检修１．故障现象（１）调节波长ｋ时，旋转波长调节钮有时轻松、有时紧。（２）波长调节失灵，表针指示无变化。２．分析判断该机波长的调节是靠彼长钮上的橡皮轮与波长刻度盘的摩擦作用，从而带动单色器内部的凸轮连杆机构而使色散棱镜转动来实现...     

原子吸收分光光度计中石墨炉自动进样器的自动排气泡装置

本文介绍了原子吸收分光光度计的石墨炉自动进样器自动排气泡装置。该装置利用了自动进样器内部玻璃注射器结构的改变而使其中的气泡(空气)自动地被排除，从而提高了样品进样体积的精密度和准确度。     

72型分光光度计的使用和维修

上海第三分析器厂生产的721型分光光度计,是一种常用的可见分光光度计。它具有取样少、分析快、灵敏度高和结构紧凑等特点,因而许多工矿企业、医院以及科研单位用该仪器作定量比色分析。721型分光光度计由光源、单色器、狭缝调节、比色皿座、稳压电源和电子放大器等部件组成,仪器方框原理图如图1所示。     

Adaptive finite element analysis of steel girder deck pavement

This paper shows a more exact and practical finite element model of the steel girder deck pavement. Based on Mindlin thick plate theory, a 12-node solid thick plate element was constituted to analyze the pavement. The computation result was compared with that by traditional 4-node and 8-node thick plate finite element, and is satisfactory. A combined plate beam element method is presented to investigate the stiffened plate. A 6-node solid thin plate element was constituted to analyze the top plate based on Kirchhoff thin plate theory. The stiffeners acting as the vertical supporting function mainly are taken as Euler beam elements. A method of using the linear interpolation to realize the longitudinal displacement and the cubic Hermite interpolation to the vertical displacement is presented to analyze the stiffeners. In addition, it is essential to consider the displacement coordination between the top plate and stiffeners. A node-to-node contact scheme, which is applicable for three-dimensional contact analyses involving large deformations, was used to treat the contact problem between pavement and stiffened plate by Lagrange multiplier methods.     

Vibration analysis of rectangular Mindlin plates with internal line supports using static Timoshenko beam functions

In this paper, the vibration characteristics of rectangular Mindlin plates with internal line supports in one or two directions are studied by using the Rayleigh–Ritz method. The static Timoshenko beam functions are employed as admissible functions, which are composed of a set of transverse deflection functions and a set of rotation-angle functions due to bending. The static Timoshenko beam functions are derived from a point-supported strip of unit width taken from the particular plate under consideration in a direction parallel to the edge of the plate and acted upon by a series of static sinusoidal loads distributed along the length of the strip. It can be seen that the suggested approach is very simple mathematically, and each of the beam functions is only a sine or cosine function plus a polynomial function of not more than the third order. A unified program can be easily prepared, because the changes in boundary conditions, number and locations of internal line supports and thickness ratio of the plate will result in a corresponding change of only the coefficients of the polynomials. Both high accuracy and low computational cost have been verified by convergence and comparison studies. In addition, it can be seen that the admissible functions presented in this paper can also properly describe the discontinuity conditions of the shear forces at the line supports. Therefore, accurate results can be expected for the analysis of dynamic response and internal force distribution of the plate.     

Strength calculation for forged straight bevel gear teeth having a linking web

When bevel gears are forged, a thin web results on the back of the teeth. This web, which results from the clearance between the dies, gives an additional strength not accounted for when the Lewis design criteria is used. To account for this extra strength a plate model is developed. The solution for this plate model can be obtained by assuming a polynomial deflection function. Using the Galerkin variational method the constants in this assumed deflection function can be calculated. The plate model is compared with a finite element model, using a general purpose program and also with experimental strain measurements. This proposed plate solution indicates an increase in strength of more than 25% in excess of that suggested by the cantilever beam model of Lewis when compared with the finite element results.     

Structural health monitoring using shaped sensors

This paper is concerned with distributed sensors to measure the response of beam and plate structures. The design of modal sensors for beam structures is well established. The design for plate structures with constant thickness sensors may be achieved by optimizing the shape of the sensor boundary, or by optimizing the effectiveness of the electrode. Most applications consider vibration control, but this paper is concerned with structural health monitoring, where the sensor output is made sensitive to changes in key stiffness parameters, for example in joints. The procedure is based on finite element models of the structures, and thus distributed transducers may be designed for arbitrary beam and plate structures. Simulated examples of a beam and a plate excited by a rotating machine are used to demonstrate the approach.     

筋板结构动力学特性边界元法解析研究

研究加筋薄板结构动力学特性多域合成的边界元建模解析方法。将矩形板沿梁划分为若干个区域,同时把梁的约束等效为作用在薄板区域上的反力,基于板、梁元件的动态基本解,由边界元法推导出带约束反力的梁和薄板的兰量控制方程,并依据耦合边界上的连续条件,运用多域合成的解析方法快速地建立筋板结构的动力学方程。数值算例表明,文中方法不但节省了计算量,而且具有良好的计算精度。     

More general expression for the torsional warping of a thin-walled open-section beam

In this study, an analytical formulation for the torsional warping function of a thin-walled open-section beam is built based on the combination of the Vlasov assumption and the Kirchhoff assumption of plate/shell theory, essentially due to Goodier and Gjelsvik. Vlasov, Timoshenko and many authors (follow Vlasov) only consider the contour warping function as the real warping function. Goodier and Gjelsvik (follow Goodier) not only consider the contour warping but also the thickness warping. For some cross-sectional constants related to the warping function such as the torsional constant, the adoption of the warping function based on Vlasov's theory or Timoshenko's theory may cause them incorrectness. On the other hand, the torsional constant based on the Goodier's theory is consistent with the one based on the membrane analogy. Thus, Goodier's theory is a good approximation for the torsional warping of a thin-walled open-section beam. To the authors’ limited knowledge, the analytical expression for the complete torsional warping of a thin-walled open-section beam has not been found in the literature. In this study, a more general expression for the torsional warping of a thin-walled open-section beam is presented. The position formulas to determine the twist center are also given.     

Fundamental study on electron beam weld sections and strengths using AA6061-T6 aluminum alloy plate

This study was carried out to establish an electron beam welding process for a nuclear fuel plate assembly fabrication. A preliminary investigation for plate fuel fabrication was conducted with a consideration of weld performance using AA6061-T6 aluminum alloy made by the electron beam welding process. The optimum welding parameters for the fuel plate assembly were obtained in terms of the accelerating voltage, beam current and welding time. The soundness of the weld region between the side plate and the end fitting for the fuel plate assembly was proven by the intact of the weld metal on the fractured surfaces. The integrity of the welds by the electron beam welding process was also confirmed by the results of the tensile test, an examination of the cross sections and the fracture surfaces of the welded specimens.     

一种钢板预弯机夹紧梁的新型液压夹紧装置

针对钢板预弯机夹紧梁快速动作时回程缸活塞杆被拉断,以及弯边时夹紧梁不能可靠夹紧钢板,提出了一种新型夹紧梁液压夹紧装置。该装置配有由蓄能器与高压小流量液压泵组成的节能型液压系统,以及能够使下夹紧梁跟随下模梁完成快速上升和快速回程的下模导向架。装置试验结果表明,两个夹紧缸同步运动误差在1 mm之内,夹紧力满足设计要求,夹紧梁运行稳定、可靠。     

Vibrational energy flow analysis of penetration beam-plate coupled structures

This study concerns the transmission of vibrational energy through beam-plate junctions by energy flow analysis, which is an analytic tool for predicting the frequency averaged vibration response of built-up structures in the medium to high frequency ranges. A semi-infinite beam perpendicularly connected to an infinite plate is studied using the wave transmission approach. To calculate the power transmission and the reflection coefficients of the beam-plate junction, compatibility and equilibrium conditions are applied when each wave component is incident on the beam and plate, respectively. Power coefficients are calculated and plotted against frequencies for different dimensions and the directivity pattern of the scattered waves in the plate show close agreement with that of the rigid inclusion as the frequency increases. The results obtained are applied to the finite beam and the circular plate coupled structure, and the energy densities obtained from energy flow analysis show better agreement with analytic solution results as frequencies are increased.     

基于ADAMS弹性浮动研磨机的动力学仿真

基于金刚石弹性浮动研磨的原理,运用Pro／E软件完成弹性研磨机的三维实体建模,并将该模型导人到多体动力学分析软件ADAMS中,利用它白带的AUTOFLEX模块将弹性梁、弹性垫转化为柔性体的模态中性文件,从而得到刚柔混合模型。仿真分析结果表明．丁件的跳动量将直接影响金刚石表面研磨质量,分析了弹性梁的长度、研磨压力及研磨盘的不平整度对工件跳动量的动力学分析。