基于载荷谱传动箱箱体动载系数分布研究

针对某特种车辆综合传动箱体强度过剩,质量过重的现状,需要对箱体进行进一步优化。而在优化过程中,传统方法基于转速转矩的经验公式计算一个较大的动载系数,减少了后续优化空间。基于载荷谱对平稳传动过程中的动载系数进行研究,首先对该箱体进行台架试验,测得危险部位的载荷谱,其次针对这些载荷谱进行处理获得一段平稳时间历程中的动载系数。运用极大似然法和拟合优度AD值对这些动载系数进行分布识别以及检验,最终获得99百分位的动载系数,并将其与经验公式计算动载系数进行对比,结果表明在平稳传动条件下,经验公式计算动载系数偏大,结构设计偏于保守,而99百分位动载系数较为合理,有助于轻量化设计的充分实现。     

圆柱齿轮动载系数的计算问题

分析了有关动载系数各种计算的方法的原理与特点，列举五个齿轮传动实例，依据美，英，ＩＳＯ等计算法进行动载系数计算，并对其计算结果进行了分析与总结。     

动载滑动轴承润滑设计计算的研究进展

本文对动载滑动轴承润滑设计计算的研究进展进行了综述和分析，并提出了未来动载滑动轴承研究所要解决的问题。     

变频调速工况下起重机起升机构动载荷分析

通过建立变频调速工况下的起重机起升机构数学模型,对该系统进行启动动载荷理论分析,并利用Matlab对影响动载系数的各参数进行了数值仿真。计算结果表明变频调速技术可有效降低电动机的启动动载系数,使起重机加减速更加平稳,也有利于提高整机使用寿命,对起重机起升机构的设计计算和动载系数的选择起到理论指导作用。     

油膜轴承传动轴系动载系数计算方法

针对传动轴系动载荷变化难以准确用数学函数描述的问题,基于刚体动力学理论,综合考虑轴系刚性与弹性振动特性,提出近似求解动载荷的分析方法,建立轴系动载荷分析模型。通过分析现有油膜轴承试验装置中传动轴系的机械结构组成,推导传动轴系在启制动工况突变时的动载系数计算公式;根据传动轴系的结构参数,确定动载系数取值范围;同时给出该动载系数模型在工程应用中的典型形式。计算表明：轴系在启制动之前,相比没有静压润滑的情况,使用静压润滑的油膜轴承的动载系数相对较小,振动对其油膜稳定性的影响较小。     

高速重载齿轮传动动载系数计算方法

从动力学的角度研究齿轮传动的动载荷和动载系数,首次定量考虑到冲击激励对动态特性的影响,提出一个新的动载系数计算公式。通过算例与ISO标准的动载系数计算B法进行比较分析,二者结果十分吻合,证明该法的正确性和可靠性。     

轮胎集装箱门式起重机起升动载系数的有限元计算

起重机起升动载系数的大小,对起重机的设计、整机重量、安全性和经济性等都有较大的影响。建立了轮胎集装箱门式起重机有限元模型,计算得出不同位置处起升动载系数值,并与实际测试结果进行对比。验证了有限元计算的准确性,研究结果具有较强的实用价值。     

基于VB和Matlab的光杆起升系统的动力学仿真

本文建立了光杆起升系统的动力学模型,并对其进行仿真计算。给出了起升系统的各阶固有频率及相应的主振型,给出了开始起升工况下起升系统各部件的载荷曲线、最大动载和动载系数,分析了各输入参数对动载系数的影响。以上理论分析,能为光杆起升系统的优化设计提供一定的理论依据。     

基于BP神经网络的齿轮计算应力修正系数计算研究

由于动载系数和齿形系数计算繁复 ,给齿轮计算应力的求解带来不便。本文提出了使用 BP神经网络映射齿轮动载系数和复合齿形系数的近似算法 ,以便减少其计算规模 ,提高齿轮计算应力的求解效率。其映射结果表明使用该方法求出的动载系数和复合齿形系数是可行的和高效的     

永磁直驱式起重机起升动载效应分析

以永磁直驱通用桥式起重机为研究对象,建立了起重机起升机构多自由度力学模型,利用MATLAB中的Simulink软件进行了动载效应仿真计算,计算结果显示起升动载系数受滑轮组倍率的影响较大,受主梁刚度的影响较小。     

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...     

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。     

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.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.     

Fractional order nonsingular terminal sliding mode control for flexible spacecraft attitude tracking

This paper investigates a fractional terminal sliding mode control for flexible spacecraft attitude tracking in the presence of inertia uncertainties and extern...     

奥氏体不锈钢表面双辉等离子渗锆的动力学

利用双辉等离子渗金属技术在0Cr18Ni9Ti奥氏体不锈钢表面制备了一层均匀、致密、呈良好冶金结合的渗锆合金层,并对1 060℃下的渗锆动力学进行了研究。结果表明:随着距锆合金层表面距离的增加,锆元素的含量呈梯度递减,扩散系数逐渐减小,而扩散激活能逐步增大;在1 060℃采用双辉等离子技术渗锆时,渗锆合金层表层的空位密度为2.945×(1012~1013)cm-2,与相同温度下采用常规渗金属工艺相比,提高了1~2个数量级。     

气化炉三维扫描测量与数据处理

以德士古气化炉耐火砖的内壁蚀损检测设备为基础,对采集到的点云数据做了进一步处理.通过对数据的筛选和剔除,实现了数据点的平滑降噪细化和精简.然后利用点云对整、网格划分和分色显示等方法,最终完成了内壁腐蚀情况的三维建模.重点讨论了点云数据的预处理及后处理的方法,并根据内壁耐火砖的腐蚀阈值,提出了一种气化炉内壁腐蚀区域的识别与分割方法.对耐火砖的腐蚀分析、气化炉的生产与维修提供了可靠依据,并在工程应用中获得了一致认可.