传递路径分析方法用于农用车振动控制的研究

使用传递路径分析方法对农用车驾驶员座椅振动控制进行了研究。介绍了传递路径分析方法的基本原理,提出了一种精确的驾驶室振动系统传递函数测试方法,通过传递函数实验和工况实验建立了完整的TPA模型。采取了一种快速的方法计算激励力,然后计算出了各传递路径贡献量。通过将路径合成值与实测值的对比,验证了TPA模型的正确性。结合相位和幅值对驾驶员座椅的振动进行了传递路径贡献量分析及路径问题识别。找出了引起振动峰值的主要路径,并通过分析找出了这些路径贡献量大的原因,为该振动系统的后期优化提供了依据。     

圆柱壳体基础隔振系统导纳功率流特性

针对圆柱壳体基础上动力装置隔振问题,建立复杂振源激励、多弹性支承、柔性圆柱壳体多维耦合传递矩阵力学模型。基于经典薄壳理论和模态叠加原理,同时计及奇偶模态响应,给出两端剪力薄膜支撑各向同性圆柱壳体的点导纳解析表达式,以导纳矩阵形式表征不同激励组分与速度响应的交叉耦合关系。考虑弹性支承的多维波动效应,运用子结构导纳法推导整体系统的功率流传递方程。研究表明:振源垂向、横向激励力与倾倒力矩诱发的隔振器纵向及弯曲谐振是中高频域系统功率流提高的主要原因;力矩激励对于柔性壳体基础功率流传输具有重要影响;壳体基础的径向弯曲振动在整个系统能量传递中占据支配地位,与其相关的弯曲机械波是主要结构声源。所用建模分析方法具有模块化延拓性,旨在为系统结构参数优化及后续的主被动一体化控制策略确立理论依据。     

车内噪声传递路径分析方法探讨

为了指导汽车NVH工程师更好地进行故障诊断和声学设计,介绍了传递路径分析（TPA）方法的基本原理,详细分析传递函数和激励力的测量方法,并以某型汽车发动机振动噪声向车内传递为例,介绍TPA方法的应用。试验结果表明,应用TPA方法可有效、方便地进行噪声源识别和贡献分析。     

多旋翼无人机振动传递路径分析

为了确定多旋翼无人机每个振动传递路径对多旋翼无人机传感器振动的贡献量,运用振动传递路径分析方法,基于CAE技术建立了多旋翼无人机振动的结构传递路径有限元分析模型。通过Ansys的谐响分析,获得多旋翼无人机机身的振动响应以及振源对于响应点的频响函数,可以计算得到多旋翼无人机Z方向振动贡献最大。从传递路径的角度找出了对传感器振动起主导作用的环节,通过控制这些环节,有针对的采取减振措施,可以改观多旋翼无人机传感器的振动问题。     

新型传递路径分析OPAX方法研究

OPAX （Operational-X Transfer Path Analysis）法是一种新型的传递路径分析方法,利用已有的数据拟合出耦合点的激励力,计算出各路径对目标点的贡献量,从而可进行传递路径分析.它具有高效率、高精度的特点.以某中型客车为研究对象,利用OPAX法对其进行了结构传递路径分析,识别出主要贡献路径,然后采取相应措施对悬置进行改进,且取得了良好效果.     

Tikhonov正则化在运行工况传递路径分析的应用

针对传统运行工况传递路径分析(operational transfer path analysis,简称OTPA)存在的不足,通过理论和试验分析,提出基于Tikhonov正则化方法的OTPA反问题模型。首先,分析Tikhonov正则化方法的理论优势,给出Tikhonov正则化参数选择的依据,同时调节电机转速获得不同运行工况数据,利用奇异值分解方法研究壳体结构的振动传递路径,分析传统OTPA算法总贡献量误差及路径贡献量估计精度;其次,分析运行工况数据是否满足Picard条件,提出基于Tikhonov正则化方法的OTPA算法,并分析Tikhonov正则化参数对所提出算法的影响。分析结果表明,所提出的方法显著减小了总贡献量和路径贡献量误差以及路径误判现象。该研究可为振动噪声监控与减振降噪提供理论依据。     

齿轮箱类系统的结构声功率流传递特性

以齿轮箱类复杂耦合系统为背景,推导“柔性振源齿轮轴-多维柔性轴承连接路径-柔性能量接受箱壁”的子系统导纳矩阵关系式,建立了系统的结构声功率流传递模型。建模过程中充分考虑了振源的力／力矩多维激励、振动功率流传递路径的柔性以及多维耦合特征。研究了齿轮箱不同的功率流传递路径及各路径之间的耦合特征,并对传递路径的柔性和引起箱体壁横向振动的功率流进行了定量分析。研究结果显示,该模型可方便地分析各子系统性能参数对整个耦合系统功率流特性的影响。     

某商用车驾驶室振动问题的改进研究

针对某商用车驾驶室振动过大的问题,使用LMS振动测试系统进行测试.通过振动传递路径分析(TPA),发现板簧固有频率与激励源频率重叠是引起驾驶室振动过大的主要原因.通过减小板簧刚度从而降低板簧固有频率,改进后再次进行实车测试.数据分析表明,振动加速度显著减小,提高了乘坐舒适性,驾驶室振动过大问题得到解决,证明减小板簧刚度对降低驾驶室振动的有效性.     

齿轮箱类系统的结构声功率流传递特性

以齿轮箱类复杂耦合系统为背景,推导“柔性振源齿轮轴－多维柔性轴承连接路径－柔性能量接受箱壁”的子系统导纳矩阵关系式,建立了系统的结构声功率流传递模型。建模过程中充分考虑了振源的力/力矩多维激励、振动功率流传递路径的柔性以及多维耦合特征。研究了齿轮箱不同的功率流传递路径及各路径之间的耦合特征,并对传递路径的柔性和引起箱体壁横向振动的功率流进行了定量分析。研究结果显示,该模型可方便地分析各子系统性能参数对整个耦合系统功率流特性的影响。     

离心泵振动传递路径重合的解耦方法

振动传递路径分析是识别振动噪声源的重要手段,离心泵是船舶装备的核心部件之一,存在流体动力学噪声与机械结构振动辐射噪声的问题,传统路径方法无法准确识别振动源.针对以上存在的问题,提出一种适宜于离心泵的传递路径分析新方法.首先对离心泵的振动传递路径进行解耦,获得各个振动源处的激励力;其次,建立了离心泵的激励点-目标点、激励...     

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.     

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....     

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。     

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.