OIML R 107-1-2007非连续累计自动衡器(累计料斗秤)

<正>附录A(规范性附录)非连续累计自动衡器的测试程序(接上期)A.7.4.5电磁场抗扰度A.7.4.5.1射频电磁场辐射抗扰度射频、无线电频率、电磁场辐射抗扰度试验按照IEC61000-4-3[23]和表15进行。试验信号的未调制载波调整到指示的试验值。为了试验载波应按规定另外调制。A.7.4.5.2射频场感应的传导骚扰抗扰度     

小型漂浮式天线姿态的自抗扰解耦控制

研究了小型漂浮式天线姿态跟踪的自抗扰解耦控制。分析了4级风以下的海洋环境对天线姿态的影响,设计了三轴伺服执行机构校正天线指向目标卫星的姿态偏差,研究证实三轴伺服系统是一种复杂的耦合性较强的非线性系统;设计了由横滚伺服自抗扰控制器、俯仰伺服自抗扰控制器和方位自抗扰控制器组成的天线姿态自抗扰解耦控制器用于天线姿态控制;通过MATLAB仿真研究验证了自抗扰解耦控制器的性能优于PID控制器,可以较好地估计和补偿天线的内部和外部扰动,实现天线姿态的解耦控制;通过半实物仿真研究证实了自抗扰解耦控制器可以实现天线与卫星间的高质量通信。     

基于混沌鲸鱼算法的自抗扰永磁同步电机控制

针对永磁同步电机由于强耦合、非线性的特点,导致任何不确定性扰动都会直接影响控制系统性能的问题,设计了一种改进鲸鱼算法优化的二阶自抗扰控制器。通过采用混沌初始化策略改进鲸鱼算法优化自抗扰控制器参数。经过优化的自抗扰控制器的控制其性能有明显提高。仿真结果表明,该自抗扰控制器响应速度快,稳态误差小且无超调,对负载扰动具有良好的鲁棒性。     

交流永磁伺服系统自抗扰控制技术研究

随着电机设计以及电力电子技术发展,交流永磁伺服系统驱动技术得到了更多完善机会,确保其控制精度的进一步发展。本文对交流永磁伺服系统控制技术关键问题进行总结,并从电流环自抗扰控制器设计、电流环性能分析、转速环自抗扰控制器设计、转速环自抗扰控制器性能分析四方面,论述了自抗扰控制技术在交流永磁伺服系统中的应用。     

基于自适应遗传算法分步优化设计智能桁架结构自抗扰振动控制器

智能桁架结构作为一种控制结构一体化的新型空间结构,具有几何、物理可自调性,但这类结构同时具有柔性大、阻尼小、低频模态密集、模态耦合程度高以及存在多种不确定性和耦合等特点,给振动控制带来很大挑战。基于此,研究不依赖于模型的自抗扰控制技术在智能桁架结构振动主动控制中的应用,建立自抗扰振动控制器的一般框架。就自抗扰振动控制器参数较多,手工整定比较繁琐这一问题,提出基于自适应遗传算法对其进行分步优化设计的思想。最后,对区间参数102杆三棱柱智能桁架结构进行自抗扰主动振动控制仿真研究。结果表明,基于分步优化设计思想优化设计的自抗扰振动控制器首先保证了扩张状态观测器具有优秀的观测性能,从而最终保证了自抗扰振动控制器的"自抗扰"能力;优化设计的自抗扰振动控制器对结构参数的不确定性和不确定外扰都具有很强的鲁棒性,适合于空间智能桁架结构的主动振动控制。     

改进自抗扰控制谐波式电动舵机伺服系统

针对电动舵机系统的非线性、快时变等特点,提出了改进的自抗扰控制器以改善系统的位置跟踪性能。首先,给出电动舵机的系统模型及控制策略,分析了系统中非线性因素的影响;设计了改进自抗扰控制器,并利用现代控制理论给出了控制器参数的选择方法。然后,在舵机系统中进行仿真分析,验证了该控制器的可行性。最后,基于谐波式电动舵机对改进的自抗扰控制器与常规自抗扰控制器及PI控制器进行对比实验。实验结果表明:跟踪10sin(5πt)正弦信号时,改进自抗扰控制器能够消除位置平顶和速度死区,相位滞后为0.087 22rad;跟踪±1°~±15°角位置时,上升时间为9~18ms,超调量为0~7.25%,稳态均方差为0.007 60~0.010 83,性能明显优于常规自抗扰控制器和PI控制器。得到的数据显示该控制器减少了设计参数,位置跟踪超调量小,响应时间快,稳态均方差小,改善了舵机系统的动态和稳态性能。     

自适应线性自抗扰控制器的设计

自抗扰控制器对于抑制不确定的扰动有良好的效果,但其控制器参数较多且整定困难。为了实现自适应的线性自抗扰控制器,对线性自抗扰控制器的参数整定策略展开了研究。首先,设计了基于观测误差的线性扩张观测器参数自适应整定算法。接着,设计了自抗扰控制器线性反馈环节的参数的自适应整定算法。最后,利用李雅普诺夫方法,证明上述自适应整定算法得到的参数可以保证扩张状态观测器的观测误差和被控系统最终输出误差都收敛至零。实验结果表明:精密气浮运动平台低速工况下,自适应线性自抗扰控制器的参数在0.8s内即可迅速完成整定计算;线性扩张观测器观测误差绝对值小于2nm;被控精密气浮运动平台的速度波动不大于5%。自适应线性自抗扰控制器实现了控制器参数在线整定,控制器的性能表现满足要求。     

非线性自抗扰控制对偶然测量误差的抑制作用

金刚石超精密切削是加工微结构表面的有效方法,其关键技术是快速刀具伺服系统(FTS),控制器性能是FTS的一个重要性能指标。针对电磁驱动原理的快速刀具伺服系统,建立执行机构简化的传递函数模型,引入自抗扰控制器作为快速刀具伺服系统的控制器并介绍自抗扰控制器参数的整定。最后采用非线性自抗扰控制技术,并利用MATLAB仿真非线性自抗扰控制(NLADRC)和线性自抗扰控制(LADRC)对偶然测量误差的抑制作用,得出结论为非线性自抗扰控制相比线性自抗扰控制可以更好的抑制偶然测量误差造成的不利影响。     

光电望远镜伺服系统速度环的自抗扰控制

针对大口径光电望远镜惯量大、存在摩擦非线性的特点,设计了自抗扰控制器以改善伺服系统的速度响应特性.介绍了自抗扰控制器的工作原理和基本结构,给出了控制器参数的选择依据,并仿真分析了各个参数的作用效果.最后,在实际望远镜转台上和常规PID控制器进行了对比实验.结果表明,采用自抗扰控制器,既可以实现大速度阶跃响应快速无超调,...     

基于小生境粒子群优化的挖掘机器人自抗扰视觉伺服控制

为提高挖掘机器人的自主挖掘能力,设计一种基于图像的自抗扰视觉伺服控制器,对挖掘机器人的动臂、斗杆、铲斗组成的3节机械臂末端位置和姿态在x-z平面进行控制,实现自主挖掘目标任务。针对自抗扰控制器需要整定的参数较多,参数间相互影响,整定困难的特点,引入粒子群算法对控制器参数进行优化。由于原始粒子群算法存在后期易陷入局部最优的缺欠,采用小生境粒子群算法对自抗扰控制器参数进行整定优化。对粒子群及小生境粒子群算法的优化性能进行比较研究的基础上,设计了适合挖掘机器人的自抗扰视觉伺服控制器,采用小生境粒子群算法得到自抗扰控制器整定参数。搭建xPCTarget主机—目标机环境进行试验及仿真,表明小生境粒子群优化的自抗扰视觉伺服控制器控制精度高、鲁棒性强。     

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.     

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.