单立柱巷道式堆垛机有限元模态分析

针对堆垛机运行时振动、噪声大,严重影响其运行速度的问题,采用有限元方法建立单立柱堆垛机物理模型,对堆垛机结构进行模态分析,确定堆垛机结构的前几阶固有频率和振型,从而了解现有结构振动的不稳定因素,避免在动力载荷作用下发生共振。     

双立柱堆垛机立柱挠度模型及其参数优化

针对当前双立柱堆垛机立柱顶端挠度计算模型精度不高、立柱优化算法效率低等问题,以XHF-B系列1-5T双立柱堆垛机为例,提出了一种新的立柱顶端挠度计算模型和立柱参数优化方法。首先,基于微元法的思想,建立了新的立柱顶端挠度计算模型;然后,对立柱进行了影响参数分析,建立了立柱挠度优化模型,并在此基础上,采用粒子群算法(PSO)对其进行了求解;最后,采用ANSYS Workbench软件,对优化后的双立柱堆垛机进行了有限元分析,并结合有限元分析结果,对理论模型的正确性进行了验证。研究结果表明：堆垛机立柱参数优化后,立柱顶端挠度为8.619 9 mm,降低了74.8%,优化效果显著;有限元分析结果显示的立柱顶端挠度为9.159 7 mm,与理论计算吻合度为94.1%,验证了立柱挠度优化模型的正确性,可为堆垛机设计提供理论依据。     

堆垛机速度控制与立柱动态挠曲变形分析

采用多体动力学分析方法并应用欧拉-伯努利梁受载挠曲变形公式,利用叠加原理得到立柱动态挠曲变形公式,建立立柱振动微分方程,分析立柱变形影响因素。应用Simulink建立立柱变形与振动仿真分析模型并求解,得到立柱变形参数与堆垛机运行时间关系曲线,将模型分析结果同有限元分析结果进行比较。采用三种不同的速度控制曲线分析堆垛机速度控制方式对立柱变形产生的影响,揭示了堆垛机在运行过程中影响立柱变形的主要因素,从而确定较为优化合理的堆垛机速度控制方式。     

复合材料机翼试验-数值建模方法及气弹分析

针对机翼结构动力学建模中复合材料离散性引起的精度问题,以及求解速度对机翼气动弹性计算速率的影响,提出了结合模态试验和模态法建立动力学模型的方法。为了提高求解速度,基于模态贡献对机翼模态进行了截断;随后进行了全模态和模态截断的静载数值计算与试验验证。缩减模型的求解结果与全模态求解结果相比误差仅为0.25%左右,其相对于试验结果最大误差仅为6.0%,说明试验-数值建模方法能够准确描述复合材料机翼的动力学响应,并且基于模态贡献的模态截断能够缩减模型、大幅提高求解速度而不会影响求解精度;对机翼进行静、动气动弹性分析,结果表明气动弹性对机翼的动力学响应具有不可忽略的影响。     

高速堆垛机运行过程的动力学仿真

以轻型高速单立柱堆垛机为研究对象,利用建模软件建立其CAD实体模型。为了确保它在高速、高加速度工况下安全高效运行,先利用机械动力学基础知识对其振动摆幅进行理论计算,然后利用ADAMS软件对堆垛机的运行过程进行动力学仿真分析,结果显示堆垛机运行能满足设计要求,为控制堆垛机在运行过程中的振动提出优化措施。仿真分析得出的样机运动参数、振动优化等结论可为轻型高速单立柱堆垛机的运行控制提供借鉴,有利于优化堆垛机的运行过程。     

双立柱巷道堆垛机的动静态性能分析及结构改进

双立柱巷道式堆垛机是自动化立体仓库的重要组成部分,堆垛机运行效率的指标要求在不断提高。将堆垛机的运行加速度大幅提高,能有效提升堆垛机的运行效率,制约堆垛机运行效率的最主要因素是运行过程中机械结构的稳定性。本文运用ANSYS Workbench有限元分析软件对双立柱巷道式堆垛机进行仿真分析,得到堆垛机所受应力和结构变形情况,并通过预应力模态分析得到堆垛机的前6阶固有频率和振型,识别了堆垛机结构的薄软环节。在动静态分析的基础上,以堆垛机自重为衡量标准,对堆垛机提出三种结构改进方案,并通过对比分析,得到综合改进方案。满足了堆垛机强度、刚度及振动要求,提高了堆垛机运行过程的平稳性。     

单立柱堆垛机有限元振动分析

针对单立柱堆垛机运行过程中加减速对立柱产生的振动激励问题,以某单立柱堆垛机为研究对象进行有限元振动分析。建立该堆垛机的有限元仿真模型,基于不同加减速策略进行对比分析。分析结果表明,十五段S形加减速策略对单立柱堆垛机的振动激励最小,能够提高堆垛机的定位效率。     

堆垛机最佳爬行速度的确定

堆垛机的运行速度直接影响自动化仓库的生产效率，而爬行速度是满足停准精度的关键，通过计算其立柱柱端沿巷道纵向初挠度和运行时柱端的振动振幅与货架、货箱等相对位置的关系，推出确定爬行速度的计算式，并介绍了计算实例。     

基于模糊PID的堆垛机控制系统研究

自动化立体仓库中堆垛机的运行速率和定位精度是影响其出入库效率的关键因素。针对当前立体仓库堆垛机定位精度低、稳定性差的问题,设计了堆垛机的闭环控制系统结构。通过堆垛机立柱挠度与加速度变化关系的分析,验证了堆垛机速度控制的重要性,同时利用速度自适应参数模型优化堆垛机调速曲线。为了进一步改善堆垛机控制性能,设计了模糊PID控制器。采用模糊PID控制方法优化堆垛机控制参数,以西门子S7-300 PLC为研究平台,对堆垛机的速度控制进行动态研究及系统仿真建模。仿真结果表明,模糊PID控制将传统PID控制和模糊控制相结合,在一定程度上优化了堆垛机控制系统的性能,实现了堆垛机的精确定位。     

高速高加速堆垛机速度控制曲线研究与优化

将以高速高加速堆垛机作为研究对象,采用动力学分析并利用叠加原理得到立柱动态挠曲变形公式,分析影响立柱变形的因素。提出一种新型速度曲线优化控制方案,当进行长距离作业,堆垛机速度可以到达最大设计速度时选择S型速度控制曲线,当运行短距离作业,堆垛机速度无法达到最大设计速度即需减速制动时选择三角函数型速度控制曲线。此方案使堆垛机速度加速度变化连续平滑,抑制立柱变形而产生摆动,提高堆垛机稳定性。     

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.