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。     

双输出脉冲发生器等价机构的综合原理和方法

为了双输出脉冲发生器的输出摇杆在工作行程中工作区间上的起始点和终止点处的瞬时传动比相等，且等于脉动无级变速器的平均传动比，提出了Stephenson型Ⅲ级双输出脉冲发生器等价四杆机构综合方法，研究了面向基本性能指标要求的单级四杆脉冲发生机构的综合原理，建立了其数学模型，并用实例说明了该原理和方法。     

基于小波变换的平面四杆机构函数尺度综合研究

提出并解决了利用小波变换通过模糊识别进行平面四杆机构函数尺度综合的计算和方法。首先应用小波变换将给定函数转化为基准小波特征参数,然后将设计机构类型的尺寸型的输出函数转化为小波特征参数,通过模糊识别选择机构的尺寸并算出对应的结构误差,以此确定在给定区间内近似实现给定函数的四杆机构。给出的算例说明了该方法的有效性与优点。     

实现变传动比成组轨迹的混合驱动机构的综合

改变混合驱动五杆机构的尺寸参数和运动参数，可以得到不同的连杆曲线；因此可以采用混合驱动五杆机构实现具有不同传动比要求的、成组的连杆曲线。本文建立了实现成组轨迹的混合驱动机构的综合模型，实现了具有不同传动比要求的成组连杆曲线综合。     

闭环联动机构的创新设计及应用

闭环联动机构(Looped-Synchronous Mechanism,LSM)是一种特殊的单自由度闭式传动机构,具有许多相似的单元,可以产生给定传动比规律的输出.LSM构件和运动副需要满足特定的约束,其构型综合与尺度设计需要相应的方法.首先,提出基于空间Assur杆组的构型方法,基于自由度计算找出空间杆组运动副的所有...     

从动杆作近似等速运动的铰链四杆机构的线图法综合

从动杆作近似等速运动的铰链四杆机构,是指除了平行四边形机构外,从动杆在某一区间内近似地实现定传动比的铰链四杆机构。它在工业自动化仪表和机械制造中有着广泛的应用。利用本文提供的线     

齿轮五杆机构齿轮链的研究

对齿轮五杆机构建立了数学模型,运用Matlab/fsolve函数,分析了传动比及初相角对齿轮五杆机构轨迹曲线的影响,并得出了轨迹曲线的变化周期及周期表达式。利用判别法,结合实例,分析了齿轮五杆机构分支点、分支、子分支及完全旋转性识别过程。研究了传动比及初相角对机构可动性的影响,提出了在机构设计和综合过程中将无分支点作为完全旋转性约束条件,来避免运动缺陷和运动不连续。针对不具有完全旋转性的齿轮五杆机构,提出通过改变传动比及初相角的值来纠正分支,并通过实例进行了验证。该研究结果对齿轮五杆机构的设计或轨迹综合提供了理论依据和参考。     

多任务可调四杆机构刚体导引综合的符号解

提出了一种实现多任务刚体导引综合的可调平面四杆机构综合方法,导出了可调机构的刚体导引综合方程。通过调节连架杆的长度,可以实现不同任务的刚体导引综合。针对实现多个任务的可调平面四杆机构,采用数学机械法并结合计算机符号处理技术得到二杆组的全部实数解,从中任意选取两组解即可组成满足给定要求的平面铰链四杆机构。     

输电线路除冰机器人竖直摆臂机构研究

研制除冰机器人代替人工方法进行导线除冰具有重要的应用前景。分析了除冰机器人前(后)臂运动特点,得到竖直摆臂机构的设计要求。根据竖直摆臂机构设计要求,采用四杆机构实现竖直摆臂运动。基于四杆机构的封闭性,应用解析法进行了四杆机构的机构综合,并用实例说明其应用。除冰机器人实验样机验证了四杆机构综合方法是正确的,四杆机构式竖直摆臂机构满足机器人的运动所有要求。     

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。     

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...     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

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.     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

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.