发电机组转子轴系扭振模化系统双重共振的概周期解

建立了发电机组转子轴系扭振模化系统的数学模型,此模型具有平方非线性,并受简谐激励作用,应用非缄性振动的改进平均法,求得了系统的固有频率与外激励频率存在以双重共振关系ω１＋ω２≈ω３,且Ω≈ω３时的一次近似解及以应的定常解,对定常解进行了理论分析和数值计算,指出系统在周期解,周期２的概周期运动,响应存在饱和,跳跃现象,在某些参数域上有多解共存现象。     

刚性剑杆的动力稳定性Ⅱ:稳定性分析

将多尺度法与Fourier级数展开相结合，分析了刚性剑杆的动力稳定性问题，导出了稳定性边界临界曲线的近似解析解。通过实例对一刚性剑杆进行了分析计算，着重求得了第一阶模态主参激共振情况下相应的稳定区域图。结果表明，增大阻尼比，可大大改善剑杆运动的高阶谐波分量对系统稳定性的影响，但对低阶谐波分量所产生的影响并不明显。所得理论可望为刚性剑杆织机的动态设计提供一定的理论指导。     

凸轮廓面特性自适应分析的共轭曲面离散解析原理

目前,凸轮ＣＡＤ／ＣＡＭ系统中廓面分析的数学模型是刚性的,这从根本上制约了凸轮ＣＡＤ／ＣＡＭ系统的柔性。本文将廓面分析建立在共轭曲面理论的基础上,提出了共轭曲面分析的离散解析原理。从共轭曲面的生成过程出发,认为轮廓曲面Σ１是从动曲面Σ２以及相对运动共同作用的结果,通过对从动曲面Σ２和相对运动的分析,获得轮廓曲面Σ１上相应点的特征。作者推导了由从动曲面Σ２及相对运动获得轮廓曲面Σ１特性的公式,从数学模型上将离散运算和共轭曲面解析处理结合起来。“离散解析原理”使得计算机智能化、自适应处理解析的共轭曲面问题成为可能。这为构建高柔性凸轮ＣＡＤ／ＣＡＭ系统奠定了坚实的理论基础,并提供了有效的实现方法。     

发动机气门的动力学计算

建立发动机气门振动的运动微分方程,该模型杆端作支承运动,考虑阻尼和较复杂的边界条件。支承运动根据凸轮轮廓曲线或实测数据拟合成富氏级数,以便进行简谐运动分析。考虑阻尼较小,用摄动方法求出气门运动的近似解析解。这项工作为工程计算提供一种便捷的实用方法。     

四圆盘扭振系统三重共振的理论与实验研究

建立了具有平方非线性并受简谐激励作用的发电机组转子轴系四圆盘扭振模化系统的模型,应用非线性振动的改进平均法,研究系统的固有频率双重内共振关系ω３≈２ω２,ω２≈２ω１且Ω≈ω１时的三重共振问题,求得系统三重共振的一次近似解及稳态响应曲线,并进行了实验验证,实验结果与理论结果相符。     

机械非线性动力学分析的A-算符方法

用Adomian分解算法的思想,把机械系统中最一般的动力学模型转化为一阶标准型微分方程组,以形式上的精确解的表达式为基础构造了求解机械系统非线性模型近似解析解的A-算符方法（AOM）;在所建立的AOM的基础上,首次提出了基于AOM的符号-数值方法（S-N方法）。最后,应用AOM得到了单自由度凸轮-从动件非线性系统模型近似解析解的表达式,分析了该算法的误差。对两自由度凸轮-从动件非线性系统应用基于AOM的S-N方法进行了数值研究,得到了系统的数值计算结果。算例表明,AOM是求解非线性方程的一种可行而有效的方法。     

一种新型机械式周向振动主轴激振驱动器的原理与结构

介绍了具有ω＝ω0 ωAsin(at)输出运动规律的两自由度凸轮连杆组合机构的原理与结构；解决了周向振动钻床主轴激振驱动器设计的技术关键，为Z向振动切削加工理论应用于孔类表面加工，提供了设备技术保证。     

含时滞半主动天棚悬架系统的解析研究

研究了含时滞的半主动天棚悬架系统的非线性动力学。首先,采用平均法求出了半主动悬架系统的近似解析解,并通过Matlab仿真得到了数值解,以位移传递率作为评判指标对二者进行了比较,发现近似解析解具有令人满意的精度;然后,利用Lyapunov理论对该系统进行了稳定性分析,发现无时滞时系统始终是稳定的,含时滞系统的稳定性是随着时滞大小周期变化的,且变化周期等于激励周期,说明时滞对半主动天棚悬架系统有着重要的影响。     

密频内共振对1／2亚谐共振的抑制作用

本文通过两自由度密频近线性系统１／２亚谐共振的分析，揭示出由于密频内共振的作用，发生１／２亚谐共振时，其自由振动项幅度受到有效的抑制。通过定常响应（非平凡解）的稳定性分析，可以看出定常响应的参数稳定区域受密频内共振的影响而呈现较复杂的情况。     

密顿内共振对1／2晋谐共振的抑制作用

本文通过两自由度密顿近线性系统１／２亚谐共振的分析，揭示出由于密频内共振的作用，发生１／２亚谐共振时，其自由振动项幅度受到有效的抑制。通过定常响应（非平凡解）的稳定性分析，可以看出定常响应的参数稳定区域受密顿内共振的影响而呈现较复杂的情况。     

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.