链传动运动特性精确模拟分析的实现

铰四杆机构的运动分析方法可用于链传动运动特性的精确分析，采用ＷＩＮＤＯＷＳ编程对链传动的运动过程进行了模拟，并对链传动瞬时传动比作出了曲线，实现了链传动运动特性的计算机模拟分析。     

考虑多运动副间隙的多杆机构运动学分析

采用二状态模型来模拟间隙状态，通过非线性连续接触碰撞力的混合模型来描述接触构件之间的碰撞特性。以此模型研究含间隙的多杆机构，通过ADAMS进行仿真分析多运动副间隙对多杆机构运动特性的影响，得到不同位置和不同间隙大小对机构产生的不同影响。结果表明：在与固定杆相连的间隙位置以及中间杆的间隙位置取较小值，可令机构有较好的运动特性。为多杆机构或者高精度杆系机构的分析、设计与寿命预测奠定理论基础；同时，也有利于多杆机构的实际运用。     

六独立轮驱动管内检测牵引机器人

研制了一种用于海底管道内检测系统的无缆自治型轮式牵引机器人模拟样机。介绍了机构组成及工作原理,并分析了动态行走特性。机器人采用内置电动机及传动机构的全主动轮杆式结构,包括六只驱动臂杆和机架杆。每只驱动臂杆的首端直接安装一对主动轮,由其内的一台电动机单独控制。六只驱动臂杆周向60°等间距排列在机架的外层空间,且首尾交替、轴向交错布置,形成六独立轮双截面驱动方式。位于内层中心的机架杆,两端布置力封闭可调机构,产生驱动轮与管壁的主动预紧或解锁。该机器人具有体积小、结构紧凑、牵引力大的特点。试验证明,适合作小直径管道检测系统的理想牵引装置。     

声发射传播特性及传导方式的研究综述

介绍了声发射在各种介质和波导杆中的传播特性,叙述了已存在的传导方式,综述了在检测过程中,选择合适的传感器和波导杆以及传感器的安装位置,为检测精度的提高打下基础。     

基于三独立平台模拟喷杆装置研究

大型喷杆式植保机械在田间作业时,喷杆运动严重影响了喷雾分布。悬架系统是控制喷杆动力学行为的关键装置,既要隔离来自车体的高频扰动,又要使喷杆跟踪低频的地面坡度变化,时刻保持与植株冠面层平行。为了研究悬架减振系统对喷杆动力学行为影响机理,综合考虑车体运动耦合作用、地形坡度变化、摩擦等因素,构建了三独立运动平台,通过复合运动的叠加,真实的仿真模拟大型喷雾机喷杆动力学行为,从而为建立科学的数学模型提供了理论基础,为研究大型喷杆悬架参数优化配置提供理论依据与试验平台,有利于大型喷杆动力学特性试验方法、检测标准的完善。     

三叉杆滑移式万向联轴器滑动销杆运动分析

三叉杆滑移式万向联轴器因为可以传递更大的转矩而被广泛应用于前驱汽车的驱动桥中。其中,滑动销杆是三叉杆滑移式联轴器的重要传动部件。对滑动销杆进行运动学分析,简化几何模型并建立分析坐标系,运用方向余弦矩阵对滑动销杆的运动进行分析。通过MATLAB软件进行数值模拟并在Pro/E软件中进行运动学仿真,研究联轴器输入轴与中间轴夹角和转动频率分别对滑动销杆在三叉杆套筒孔中的运动的影响。结果表明滑动销杆运动的最大位移和最大速度都会随着输入轴和中间轴夹角的增大而增大。最大位移即振幅不受联轴器转动频率变化的影响,而最大速度则与转动频率成正比。滑动销杆的运动分析是三叉杆滑移式万向联轴器运动特性的重要组成部分,并为进一步研究其动力学特性和润滑特性提供了基础。     

一种新型二维速度和加速度测量方法研究

速度和加速度的实时测量在机械工程和土木工程中都有十分重要的意义。本文对一种新型的速度和加速度测量方法进行了研究。该方法可以实现二维速度和加速度的多点实时测量。该方法的主要原理是设计一种平面坐标检测杆,检测杆可以实时测量出杆上各点的坐标。坐标对时间数值差分可以计算出速度和加速度。将坐标检测杆精确牢固附在被测构件上进行测量。在编写了基于本方法实时计算并直观显示速度和加速度的程序后,本文以一个示例演示该方法。比较了理论解数据与该方法模拟测量数据,两者较为吻合。     

中空钢疲劳寿命试验参数研究

如何选择合理的参数在高频疲劳试验机上对中空钢的质量进行模拟检测,对评估中空钢质量至关重要。本文通过采用应力分析及应力波形分析相结合,研究得到锥形连接钎杆成品的疲劳试验参数,结果表明,采用上述试验参数,在高频试验机上对中空钢进行疲劳试验能够很好的模拟钎杆的寿命状况。     

用于功率超声磨削声学系统的阶梯型变幅杆节点位置研究

通过理论推导及有限元仿真模拟,分析找出了阶梯型变幅杆节点实际位置与传统理论位置的差别,同时分析指出超声波在变幅杆中传播时将引起材料的横向变形,泊松比的存在使纵向弹性变形会引起材料的横向变形。分析了阶梯型变幅杆振动特性,指出节点向细端移动可以减小节盘的振动。通过阶梯型变幅杆节点位置实验,验证了以上分析结论。     

结构热变形对机床进给系统热误差的影响分析

以某企业生产的T-500B高速钻铣加工中心为研究对象,利用有限元仿真软件对机床实际工况下丝杆进给系统的热特性进行模拟分析,寻找出进给系统与结构铸件间的整体热变形规律,同时还根据丝杆的热变形规律,分别通过考虑结构铸件变形与否这两种不同情况,建立起机床进给系统相应的热误差模型并进行模拟验证分析,最终得出了两种情况下丝杆在有效行程范围内的热误差曲线,提高了热误差模型的准确性,对机床热误差预测模型的构建具有一定的参考价值。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.