利用半导体自动测试设备测定负载板继电器性能

本文对半导体自动测试设备以及负载板继电器的特点和应用进行了阐述,在此基础上提出利用半导体自动测试设备测定负载板继电器各项性能的设计思想。半导体自动测试设备采用Teradyne公司的FLEX系列机型,设计出能够适应多种继电器的测试负载版电路,测试程序界面采用Teradyne公司的Teradyne IG-XL V5.10.55_flx版本,通过编写VBT测试程序实现负载板开关继电器响应时间、温度等参数测试。

利用半导体自动测试设备测定负载板继电器性能

本文对半导体自动测试设备的相关概念做出了简要的阐释,并论述了负载板继电器的性能和特点,并在现有的对半导体自动测试设备及负载板和继电器的研究的基础上,提出了全新的有关半导体自动测试设备测定过程的设计理念。利用半导体自动测试设备,设计出的测试负载版电路及测试程序界面对各类继电器均有一定的适应性,通过编写一定的测试程序来对负载板开关继电器的反应时间、工作功率、温度等相关参数进行实验和测试。

两侧有固体层负载时板中Lamb波的传播

本文研究了薄板二面有固体层负载时板中Lamb波的传播。从弹性波理论出发并结合相应的边界条件，导出了板中Lamb波的色散方程。数值计算表示，不管作为自由状态时板中Lamb波相速（板厚取定时）是大于或小于外层固体的声表面波波速，板中对称及反对称模式的Lamb波相速都随着外层固体层厚度增加而变化并且渐近于外层固体的声表面波波速。数值计算又表明，对很薄的板，板中对称及反对称模式的相速均随负载板的厚度呈线性变化。这二种模式都可以供传感器制作的选择。

基于虚拟仪器技术的固定电话用户板测试系统

介绍一种用于ATLCD/ATLCE板的自动化测试系统。该测试系统由电话局交换设备、用户板、负载板、NationalInstruments公司的PXI 10 42机箱、PXI 8174控制器、PXI5 411信号发生器、PXI 40 70数字万用表、PXI 65 0 8多路数字输入输出卡、PXI 65 3 4高速数字输入输出卡、基于虚拟仪器 (LabVIEW )的人机界面组成。该测试系统能在很短的时间内完成大量测试项目的自动化测试 ,测试结果的精确度和稳定性很高 ,操作界面友好 。

舰船配电网络拓扑表达新方法

传统的基于邻接矩阵和支路-节点关联矩阵的电网拓扑表达方法在解决舰船配电网结构的规划问题时存在着局限性。本文定义了配电板关联矩阵和负载-配电板关联矩阵用于舰船配电网络的拓扑表达,建立了舰船配电网辐射状结构约束的数学模型,给出了舰船配电网属性的计算方法。算例结果验证了该拓扑表达方法及约束条件数学模型的准确性。

Analysis of stability of support and surrounding rock in mining top coa of inclined coal seam

The study analyzes the characteristics of roof movement in mining top coal of inclined coal seam,and establishes the mechanical model of support and surrounding-rock stability in inclined coal seam.Besides,this study carries out the numerical calculation and field observation of roof movement and support stability,and provides the critical control measures.The results show that the fracture firstly appears in middle-upper roof and extends upwards in top coal caving in inclined coal seam;regular and irregular caving zones appear in middle-upper stress concentration region,and the asymmetric caving arch is finally formed.Support load of middle-upper working face is larger than that of the middle-lower face;dynamic load coefficient of upper support is large,and the load on the front of support is larger than that on the rear of it,which leads to poor support stability.Stability of support and surrounding-rock system depends mainly on upper-support stability.

Research on hydraulic-powered roof supports test problems

The load-bearing characters of hydraulic-powered roof support with dual telescopic legs were analyzed. With a specific type hydraulic-powered roof support with dual telescopic legs for research object, the inside load test problems in factories was analyzed, and the correct test methods were given, which can enhance the test efficiency and make the factories away from the error design of hydraulic-powered roof supports and legs.

Membrane action in lateral restraint reinforced concrete slabs

Based on the assumption of additional three-hinge arching action,an analytical method was proposed to predict the additional load of lateral restraint reinforced concrete (RC) slab under compressive membrane action (CMA),and its ultimate load could be obtained by adding pure bending load. The experiment of twelve one-way RC slabs supported by shear-walls was carried out,and the calculations of this proposed method provide good predictions for the experimental evidences. The influence of some design parameters on bearing capacity was also investigated. It is shown that the effect of vertical load on ending shear-wall on the ultimate load capacity can be generally neglected when the bending restraint is satisfied. The additional load capacity also decreases with the increase of the span-to-height ratio of central slab. When reducing the reinforcement area,the additional load capacity is increased,and this method can be used to save steel or enhance the ultimate load capacity of low steel ratio slab.

Cutting Behavior of Acrylic Thick Sheet Subjected to Squared Punch Shearing

This paper describes the cutting behavior ofa 1 mm thickness acrylic worksheet sheared by a squared punch/die apparatus. In the shearing experiment, a load cell and a high speed camera were used for investigating the shearing load response and the deformation behavior of the worksheet. It was found that the mechanical parameters, i.e., the punch-die clearance and the feed velocity of the punch, affected the shearing load response, the cracks initiation behavior and the separation capability of the worksheet. Additionally, a FEM （finite element method） analysis simulating a two dimensional shearing deformation was carried out in order to investigate the influence of punch-die clearance on the failure patterns. Through this simulation, it was revealed that the punch-die clearance remarkably affected the tensile state of stress concentrated in the sheared zone and the crack initiation behavior of the worksheet.

A Comparative Study on the Flexural Behaviour of Waffle and Solid Slab Models When Subjected to Point Load

The determinations of flexural behavior of some engineering structures are based on different theories and equations, but it has been observed that some of these equations may not give true representation. This work has looked into the difference that may occur between theoretical and experimental results. An experimental test carried out on models of waffle and solid slabs structures were described and results from twenty test samples are presented. Each specimen was subjected to an incremental axial loading of 1 kN interval after 28 days of casting. The flexural moments, deflections and crack width at failure were obtained. The experimental flexural crack and theoretical flexural cracks for both types of slabs were compared. The result for flexural moments for waffle was 5.526 kNm, while solid slab was 3.684 kNm. The deflections showed that waffle slabs has 3.64 mm while solid has 9.28 mm, hence waffle has a higher structural stiffness than solid slabs, but the flexural cracks did not give the same results especially for the estimated crack width. It was concluded that estimated results based on developed equations may not be accurate because it is based on ideal situation.

Analysis of structural hot-spot stress in orthotropic plates

On the basis of the actual steel deck structure of Taizhou Bridge, this paper carries out hot-spot stress analysis on some key spots by using the finite element model which simulates local structure of orthotropic steel bridge decks. A finite element model is established for local structure of orthotropic steel bridge decks, and in the analysis of linear elasticity of the structure, face load is employed to simulate the loads from vehicle wheels. Analysis results show that main stresses are relatively heavy at the joints between diaphragm plates, top plates and U-shaped ribs and the joints between diaphragm plates and U-shaped ribs. These joints shall be regarded as key points for hot-spot stress analysis. Different mesh densities are adopted in the finite element model and the main stresses at different hot spots are contrasted and linear extrapolation is carried out using extrapolation formulae. Results show that different mesh densities have different influences on the hot-spot stresses at the welded seams of U-shaped ribs. These influences shall be considered in calculation and analysis.

Solar-Powered Direct-Current Loads in Small Buildings

Traditional light bulbs （e.g., incandescent, fluorescent） use too much electricity, convert very little energy into light of sufficient quality and in their production use toxic contaminants. During the last few years, a new type of light source, LED （light emitting diode） bulb, has gained increasing popularity and its costs are set to plunge even further. LED bulbs offer many advantages over traditional sources, and they can be used as a direct replacement to existing lighting. This paper will use a spreadsheet-based analysis with hourly solar data supplied by Ecotect to show that, the efficiency of LED installations can be increased when used in conjunction with photovoltaic modules, as the two generate （and use） DC （direct-current） electricity, thereby eliminating intermediate-level losses in the electronic circuitry. If a storage battery is included, the solar panels generate electricity during the times when the occupants are not necessarily using the lighting, but the stored electricity can be used to power the lighting when the energy is required. The latest results demonstrate that, a slight reduction in the required floor area to be lit allows the solar-battery-LED system to be implemented in small buildings using a storage battery size that is within the range of present commercial devices.

Construction and evaluation of nitric oxide generating vascular graft material loaded with organoselenium catalyst via layer-by-layer self-assembly

A new biomimetic material for artificial blood vessel with in situ catalytic generation of nitric oxide(NO) was prepared in this study. Organoselenium immobilized polyethyleneimine as NO donor catalyst and sodium alginate were alternately loaded onto the surface of electrospun polycaprolactone matrix via electrostatic layer-by-layer self-assembly. This material revealed significant NO generation when contacting NO donor S-nitrosoglutathione(GSNO). Adhesion and spreading of smooth muscle cells were inhibited on this material in the presence of GSNO, while proliferation of endothelial cells was promoted. In vitro platelet adhesion and arteriovenous shunt experiments demonstrated good antithrombotic properties of this material, with inhibited platelet activation and aggregation, and prevention of acute thrombosis. This study may provide a new method of improving cellular function and antithrombotic property of vascular grafts.