四杆直线导向机构综合新方法的研究

提出了四杆直线导向机构综合的数值比较法,运用鲍尔点附近的连杆曲线以３阶精度逼近给定的直线,建立起了连杆曲线中具有直线段的四杆机构数据库。将给定的直线段条件与数据库中的参数进行比较,即可得到一系列满意的四杆直线导向机构。该数值比较法解决了四杆直线导向机构综合的难题。应用该方法编制了一套四杆直线导向机构综合的设计软件,对单、双直线导向机构进行了综合与仿真,实现了导路上无摩擦、磨损的四杆直线导向机构综合的自动化与可视化,大大缩短了设计周期。     

平面四杆机构刚体导引综合的小波特征参数法

针对傅里叶级数理论不能进行非整周期刚体导引综合的问题,提出了基于Haar小波级数的解决方法,将早期提出的解决平面四杆机构轨迹综合问题的方法扩展到平面四杆机构的刚体导引综合中。通过对刚体转角和其对应基本尺寸型的连杆转角小波系数进行分析,发现了二者的内在联系。在此基础上建立了101 408组基本尺寸型的平面四杆机构刚体导引输出特征参数数据库。将位置输出问题转化为平面四杆机构轨迹综合问题,并给出了计算平面四杆机构实际尺寸和机构安装位置参数的理论公式。利用建立的数据库和理论公式,实现了平面四杆机构非整周期刚体导引综合。以生产线上的输送工件的铰链四杆机构为例,证明了本文方法的有效性和可行性。     

用快速傅里叶变换进行球面四杆机构连杆轨迹综合

根据给出的球面四杆机构连杆轨迹的数学模型,借助傅里叶级数这一数学工具,对连杆轨迹的谐波成分进行理论分析,发现连杆轨迹的谐波成分与其相应转角函数谐波特征参数和机构尺寸参数的内在联系。确定球面四杆机构的基本尺寸型,在此基础上建立包含600余万组机构基本尺寸型的球面四杆机构连杆轨迹的谐波特征参数数值图谱库。利用傅里叶级数理论建立球面四杆机构处于空间任意位置时连杆曲线的数学方程,推导出计算机构的实际安装尺寸、连杆上点的位置和机构安装尺寸参数的理论计算公式。利用建立的谐波特征参数数值图谱和推导的理论公式解决了球面四杆机构的轨迹综合问题,最后给出算例证明本方法的可行性。     

Fourier变换在空间连杆机构轨迹综合中的应用

从空间连杆机构连杆曲线的Fourier级数表达式入手,解决了空间连杆机构连杆曲线的数学描述问题.通过分析找到了连杆曲线谐波特征参数与连杆转角算子谐波特征参数之间的内在联系,在此基础上给出了轨迹综合的步骤,为解决空间连杆机构的轨迹综合问题提供了一个新的思路.最后通过解决球面四杆机构轨迹综合问题,证明了本方法的有效性.     

平面连杆机构轨迹综合的自相关法

提出了利用连杆轨迹曲线的自相关变换进行平面连杆机构轨迹综合的计算机方法。用该方法建立了已知连杆机构的轨迹曲线的特征参数数据库，从而可以在已建立的数据库中快速地查找出能够实现给定轨迹的连杆机构，以达到近似实现多点轨迹曲线的机构综合．     

基于小波特征参数的平面四杆机构轨迹综合方法

小波分解可以在不同尺度下对函数曲线的特征进行提取,基于该理论,首先,对平面四杆机构连杆轨迹曲线进行小波分解,利用归一化处理方法提取轨迹曲线的小波特征参数,给出了平面四杆机构连杆轨迹曲线的小波特征参数近似描述方法。进而结合数值图谱法,将11维非整周期轨迹综合问题转换为6维机构尺寸型检索问题,同时建立包含3 004 281 900组平面四杆机构的机构尺寸型数据库。根据轨迹曲线小波特征参数的特点,利用多维搜索树,将各相对转动区间内的机构尺寸型进行分区,建立索引关键字数据库。从而通过比较给定轨迹曲线小波特征参数与索引关键字,查找并提取目标机构所在叶子结点中机构尺寸型的小波特征参数,建立自适应图谱库。在此基础上,根据给定设计要求的小波特征参数与自适应图谱库中的小波特征参数的相似程度,检索出满足设计要求的机构尺寸型。再根据理论公式计算目标机构的实际尺寸及安装位置,实现平面四杆机构非预定相对转动区间轨迹综合问题的求解。最后,利用小波特征参数法对滚压包边设备的滚轮进给机构进行设计,验证本方法实用性和有效性的同时,为传统滚压包边提供新的思路。     

平面四杆机构综合数值比较法的研究

提出了平面四杆机构综合（包括函数综合、轨迹综合和导引综合等三类基本问题）的数值比较法。在研究了四杆机构的连杆转角曲线和主从动连架杆转角曲线的基本特征后,根据当今计算机的强大的计算、存储、比较、检索与图形能力,对四杆机构综合的三类基本问题提出了相应的转化方法,均可以求出一系列基本满足给定要求的解,而后再根据每类问题提出的约束条件进行优化,得到满意解。利用该软件开发的软件可实现连杆机构综合的自动化与可视化。     

带有预定时标平面四杆刚体导引机构尺度综合的研究

提出并解决了利用连杆转角函数谐波成分“数值图谱”进行带有预定时标刚体导引机构尺度综合的计算机方法。在分析了刚体导引位置转角函数与连杆转角函数之间的内在联系及解决了用理论计算方法确定机构实际尺寸、连杆上标线的位置及机构安装尺寸参数关键问题的基础上, 以曲柄摇杆机构为例, 用该方法建立了一个含有２０３５０ 组机构基本尺寸型连杆转角函数的谐波成分数据库。从而可以通过模糊识别方法在已建立的数据库中快速寻找出能够实现给定带有预定时标刚体导引的多个机构, 达到近似实现带有预定时标要求刚体导引机构的尺度综合。给出的算例充分说明了本方法的有效性与优点。     

利用数值图谱法进行多杆直线导向机构的轨迹综合

给出了类四杆五杆机构的几何约束条件,讨论了类四杆五杆机构连杆轨迹与连杆转角算子之间的关系,建立了包含137052组机构基本尺寸型的特征参数数值图谱库,实现了对带有预定时标多杆直线导向机构的轨迹综合,文中最后给出了算例对其进行验证。     

用连杆转角曲线法实现四杆机构轨迹综合及其多解评价的研究——平面连杆机构综合可视化方法之二

本文利用连杆转角曲线法进行平面四杆轨迹综合，在对任意轨迹曲线的“无穷多点”实现了多解后，提出一种基于神经网络的多解排序方法，训练了一个前馈型神经网络在规定的条件下对多解进行评价、排序。在整个求解过程中实现了可视化，对设计中求得的机构还可以进行运动仿真，软件的界面设计合理，人机交互十分方便。     

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.