交通事故现场三维摄影测量现场线性标定方法

照相机内外参数的标定是利用计算机视觉理论进行交通事故现场测量的基础。线性成像模型是照相机最简单、最基本的成像模型。根据交通现场的静态特点,可以对事故现场摄影时照相机的成像参数进行现场标定。为了提高测量速度,对标定参照物上的标定点进行交互式自动识别。本文提出的标定点设置方式和提取方法,可以克服阴影干扰。用基于误差统计的方法对标定点进行优选,可以确保对照相机线性成像模型的可靠标定。     

加筋地基承载力特性及破坏模式的试验研究

利用自制的模型试验设备,做了一系列加筋地基的模型试验,应用数字照相变形量测技术,结合地基土压力和基础的沉降的量测来研究加筋地基的加筋机理和变形破坏模式。基础荷载作用下的地基变形场用连续的数码相片记录,然后用数字照相变形量测技术分析得到地基的增量变形场和地基的破坏面。试验结果表明,无加筋地基的破坏模式和经典的地基破坏模式吻合较好,加筋地基的破坏模式会因为加筋体的存在而发生一定程度的改变。文中模型试验所揭示的加筋地基的变形破坏机理可作为加筋地基的极限分析的基础。     

Ability of youth operators to reach farm tractor controls

Farm tractor work is commonly assigned to young people on North American farms, where tractors account for the majority of deaths and major portions of non-fatal trauma to working youths. However, little is known about the potential mismatch between the anthropometric and physical characteristics of children and tractor characteristics. The purpose of this study was to evaluate the ability of children of varying ages and percentiles to reach major controls on 45 tractors in common use in the US. The main study finding was that many tractor controls, especially those that are hand-operated, may not be effectively reached by the majority of youth operators aged 12 to 16 years. The study raises further serious questions about the ability of children to safely operate tractors in common use on US farms and calls for reconsideration of age guidelines for the assignment of children to tractor work on farms. This study provides novel ergonomic evidence about the ability of children to reach controls inside agricultural tractor cabins. The approach could be applied in similar situations where youths may operate other vehicles or machines. Study findings support the establishment and refinement of policies and guidelines related to youth tractor operation.     

Characteristics of welding distortion/residual stress generated by fillet welding with laser beam and verification of generality of its highly accurate prediction

It was found that the characteristics of welding distortion and residual stress generated by laser beam welding (LBW) had the same tendency as those by arc welding but that the absolute value was small. Moreover, the process of LBW is quite different from that of arc welding, the validity and generality of the dominant factors to predict high accuracy welding distortion and residual stress generated by welding could be verified by the high accurate prediction of welding distortion and residual stress which had been proposed based on arc welding. Inherent force was proposed as a parameter which could indicate the magnitude of compressive residual stress, which might influence the load-carrying capacity. Although inherent forces with LBW were 40% that of arc welding, it was found that control of welding heat input was important so as to improve the load-carrying capacity.     

锻造操作机升降倾斜机构的设计

阐述了双平行四连杆机构钳架的工作原理,分析了其升降及倾斜机构的运动机理,并针对设计要求,计算出平行升降缸及倾斜缸的行程.投产情况表明此结构合理、运行安全可靠,为以后设计提供参考.     

组合在金属铆爪上具有自主适应功能定位挡块的设计

带有金属接头的橡胶软管总成产品是汽车十分重要,甚至是关键部件。为使该产品满足设计要求,有时就需对金属接头上铁套的铆合部位实行较为准确定位,同时还需解决因铁套在铆合过程中由于塑性伸长对定位挡块刚性破坏问题。为此,就需要一款能够自主适应铁套在铆合过程中的塑性伸长-组合在金属铆爪上的定位挡块,从而达到以铁套端面为定位基准铆合制作产品之目的。     

建筑爆破倒塌过程的近景摄影测量分析(Ⅲ)——测试分析系统

将近景摄影测量分析系统引入工程爆破领域,对建筑物爆破倒塌过程的运动轨迹进行摄影测量分析。本系统分为影像采集、影像解析和专业化的数据后处理三个步骤,最终实现定量分析各种爆破过程及爆破效果的评价参数。实践证明基于非量测用摄影机的建筑爆破倒塌过程的摄影测量分析系统是经济、可行、可靠的,能够满足工程分析的精度要求,有利于剖析机理、总结规律,进而指导工程实践。     

数字摄影量测在混凝土变形试验中的应用

利用数字摄影量测技术以及岩土工程数字摄影量测软件系统,采用MTS815实验机,对若干10 cm立方体混凝土试件进行了压缩变形观测试验,得出了试件表面的位移矢量、位移场和局部测点变形的发展演变过程;分析了混凝土裂缝的分布和发展规律,定量地测出了裂缝宽度。并且,利用数字摄影量测技术对混凝土弹性模量的动态变化规律及计算方法进行了研究,为混凝土力学性能的进一步研究提供了参考数据。     

微小型无人机全姿态增稳控制系统的设计与实现

针对传统微小型无人机在飞行过程中存在的稳定性问题,指出影响稳定的因素。提出一种基于三轴陀螺和倾角传感器构成全姿态增稳控制系统的设计方案,采用EWTS82三轴陀螺和SCA100T双轴传感器组成姿态增稳硬件控制,结合软件增稳控制,成功应用到某型微小型无人机上。大量的试飞结果表明,基于三轴陀螺和倾角传感器构成的姿态增稳控制系统优于传统的测量单元,有很好的应用价值。     

浅谈某工程预应力管桩质量问题的分析与处理方法

预应力管桩具有单桩承载力高、适用范围广、施工速度快等优点。但在复杂的地质情况下常常出现很多质量问题。该文着重分析了如何有效解决静压预应力高强度混凝土管桩(PHC)在施工中出现位移上升、管桩倾斜2个问题。