反力式制动试验台加载能力与检验结果真实性的分析

利用反力式制动试验台对前、后轮的加载能力进行了分析，并得出如下结论：（1）因存在系统的微观自激振动，致使滚筒对车轮的加载能力在一定范围内不停地波动；（2）加载能力一般不低于轴荷的60％，对于后轮行车制动力的检验，试验台加载能力的下限值可能低于60％；（3）为使后轮驻车制动力检验的加载能力不低于整车重力的20％，试验台应设置限制车辆后移的辅助设施，以提高驻车制动力的加载能力。

工程机械几种基于动力匹配引起的动力不足现象分析

介绍了几种比较有代表性的工程机械动力不足现象,并以发动机的转矩曲线与整车所需转矩曲线的匹配性进行分析,提出解决办法。包括装载机因调速弹簧变软,使其作用转速降低,导致装载机牵引力减小和液压装置动作变缓;发动机低速转矩不足使装载机铲装缓慢或无法进行铲装作业;发动机低速转矩小于挖掘机液压系统吸收转矩而导致熄火;发动机调速率过大使钻机调速严重;发动机怠速承载能力低使叉车易熄火等。故应根据具体机械的需求进行合理的动力匹配。

新型电动滚筒试验装置的改进与应用

针对现有电动滚筒试验装置部分功能不足的情况,结合实验室现场检验工作经验,对现有新型电动滚筒试验装置的功能进行改进与拓展,以满足大功率永磁电动滚筒的试验需求。由于增大了加载滚筒与输送带的包角,改进了张紧及调偏机构和加载方式,所以能够提升试验装置的加载能力和使用方便性,并能拓展其试验功能。

能量计

Coherent公司的LabMax能量计支持位置传感探测器并且与该公司目前和过去型号的传感器兼容。它有灵活的数据加载能力，可以选择设置批处理。LabMax能测量平均能量、脉冲能量、重复率和从190nm至12μm的脉冲和连续激光器的光束位置，覆盖的测量范围从1nW至30kW，从1nJ至30J，从单脉冲到10kHz。此仪器由Coherent软件和LabView驱动。

TCO′03 VS TCO′99

TCO(The Swedish Confederation of Professional Employees,瑞典劳工联盟)对大多数电脑爱好者来说并不是一个陌生的名词.由于办公设备人体工程学在国际上已经成为产品验证的一个重要项目,欧盟更要求所有用于办公的显示器必须符合人体工程学与产品安全的设计,因此,在显示器的左上角通常都能见到TCO认证的标志.

Solution to 1-D consolidation of non-homogeneous soft clay

In this work, semi-analytical methods were used to solve the problem of 1-D consolidation of non-homogeneous soft clay with spatially varying coefficients of permeability and compressibility. The semi-analytical solution was programmed and then verified by comparison with the obtained analytical solution of a special case. Based on the results of some computations and comparisons with the 1-D homogeneous consolidation (by Terzaghi) and the 1-D non-linear consolidation theory (by Davis et al.) of soft clay, some diagrams were prepared and the relevant consolidation behavior of non-homogeneous soils is discussed. It was shown that the result obtained differs greatly from Terzaghi’s theory and that of the non-linear consolidation theory when the coefficients of permeability and compressibility vary greatly.

Seismic stability of reinforced soil walls under bearing capacity failure by pseudo-dynamic method

In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by considering different parameters,such as horizontal and vertical seismic acceleration coefficients,ratio of reinforcement length to wall height,back fill friction angle,foundation soil friction angle,soil reinforcement interface friction angle and surcharge.The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25°to 45°,and increases by 2-fold when the soil reinforcement interface friction angle varies from 0 to 30°.That is to say,the bigger values the foundation soil and/or soil reinforcement interface friction angles have,the safer the reinforced soil walls become in the seismic design.The results were also compared with those obtained from pseudo-static method.It is found that there is a higher value of the safety factor by the present work.

Low cyclic fatigue performance of concrete-filled steel tube columns

Eight concrete-filled steel tubular(CFT) columns were tested subjected to cyclic loading under constant axial load. Experimental parameters included axial compression ratio, loading sequences, and strength of concrete and steel. The seismic performance of CFT columns and failure modes were analyzed. The test results show that different axial load ratios and loading sequences have effects on the load carrying capacity, ductility and energy dissipation capacity of CFT columns, as well as the failure modes of the CFT columns. The failure pattern can be categorized into two types: local buckling failure of steel tube in compression zone, and low cycle fatigue tearing rupture failure of steel tube. The seismic behavior was evaluated through the energy index obtained from each cycle.

Preparation of porous Ti35Nb alloy and its mechanical properties under monotonic and cyclic loading

The Ti-35%Nb(mass fraction) foams were prepared by a powder metallurgy method,and the microstructure and the mechanical properties of the foams under monotonic and cyclic loading were investigated.The microstructure of the foams mainly consists of β phase,and the foams exhibit the homogenous pore distribution with the average pore size of 252 μm.The foams with 66% porosity show a typical stress-strain curve of the open-cell foams,and the plateau stress is about 56 MPa.The fatigue strength of the foam is 15.12 MPa at 107 cycles.The fractographic analysis of the foams reveals that the cracks nucleate within the struts and grow in a fatigue mechanism,resulting in the acceleration of the fatigue damage of the foams.

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.

Research on bionic quadruped robot based on hydraulic driver

A prototype of hydraulically powered quadruped robot is presented. The aim of the research is to develop a versatile robot platform which could travel fleetly in outdoor terrain with long time of en- durance and high load carrying ability. The current version is 1. lm long and 0.48m wide, and weights about 150kg. Each leg has four rotational joints driven by hydraulic cylinders and one pas- sive translational joint with spring. The torso carries the control system and the power system. A no- vel control algorithm is developed based on a Spring-Loaded Inverted Pendulum model and the prin- ciple of joint function separation. The robot can not only cross a 150mm high obstacle in static gait and trot at 2.5km/h and l km/h on the level-ground and 10°sloped-terrain respectively, but also au- tomatically keep balanced under lateral disturbance. In this paper, the mechanical structure and control systems are also discussed. Simulations and experiments are carried out to validate the design and algorithms.

万吨级多功能试验系统的研制与应用

近年来,新型、复杂、巨型结构不断涌现,给设计和施工带来了巨大挑战,而现有试验设备的加载能力和加载空间均无法满足抗震试验的加载要求,尺寸效应问题突出。为此,从大吨位基座超高精度安装及控制技术、试件脆断安全保护技术、移动横梁大行程自动调整与锁紧技术、微摩擦平面静压轴承技术、超冗余并联驱动控制技术和瞬时大流量技术6方面进行攻关,研制出万吨级多功能试验系统,可实现巨型柱、巨型剪力墙等大型结构构件的六自由度加载和大型隔震支座的高速动态测试。基于研发设备,已顺利开展足尺加压成型钢管混凝土叠合柱轴压试验、钢管混凝土巨柱轴压及压剪试验、CAP1400三维隔震系统原型三向滞回加载等10余项大型试验,研究成果可为建筑、桥梁、核电能源等多个领域的关键技术提供数据支撑。

罗西V.S.舒马赫——试论摩托运动与汽车运动

2002年，罗西驾驶标致20B参加WRO英国拉力赛，但不幸翻车退出：2003年，罗西接到法拉利车队邀请并准备试驾F1．但最终不了了之。一些车迷或许会有这样的问题——摩托赛手能否顺利掌握汽车比赛驾驶技巧?这两项运动区别何在?