Design and analysis of a two-dimensional vibration control mechanism based on vibro-impact damping

The robotic drilling always generates the axial vibration along the drill bit and the torsional vibration around the drill bit,which will adversely affect the drilling precision.A vibration control mechanism fixed between the end-effector and the robot is proposed,which can suppress the axial and torsional vibrations based on the principle of vibro-impact(VI)damping.The energy dissipation of the system by vibro-impact damping is analyzed.Then,the influence of the structure parameters on the vibration attenuation effect is studied,and a semi-active vibration control method of variable collision clearance is presented.The simulation results show that the control method has effective vibration control performance.

Design and Analysis of Integrated Predictive Iterative Learning Control for Batch Process Based on Two-dimensional System Theory

Based on the two-dimensional （2D） system theory, an integrated predictive iterative learning control （2D-IPILC） strategy for batch processes is presented. First, the output response and the error transition model predictions along the batch index can be calculated analytically due to the 2D Roesser model of the batch process. Then, an integrated framework of combining iterative learning control （ILC） and model predictive control （MPC） is formed reasonably. The output of feedforward ILC is estimated on the basis of the predefined process 2D model. By min- imizing a quadratic objective function, the feedback MPC is introduced to obtain better control performance for tracking problem of batch processes. Simulations on a typical batch reactor demonstrate that the satisfactory tracking performance as well as faster convergence speed can be achieved than traditional proportion type （P- t-we） ILC despite the model error and disturbances.

Design of Discrete-time Repetitive Control System Based on Two-dimensional Model

This paper presents a novel design method for discrete-time repetitive control systems （RCS） based on two-dimensional （2D） discrete-time model. Firstly, the 2D model of an RCS is established by considering both the control action and the learning action in RCS. Then, through constructing a 2D state feedback controller, the design problem of the RCS is converted to the design problem of a 2D system. Then, using 2D system theory and linear matrix inequality （LMI） method, stability criterion is derived for the system without and with uncertainties, respectively. Parameters of the system can be determined by solving the LMI of the stability criterion. Finally, numerical simulations validate the effectiveness of the proposed method.

Proportional integral derivative controller design using Legendre orthogonal functions

The Legendre orthogonal functions are employed to design the family of PID controllers for a variety of plants. In the proposed method, the PID controller and the plant model are represented with their corresponding Legendre series. Matching the first three terms of the Legendre series of the loop gain with the desired one gives the PID controller parameters. The closed loop system stability conditions in terms of the Legendre basis function pole(λ) for a wide range of systems including the first order, second order, double integrator, first order plus dead time, and first order unstable plants are obtained. For first order and double integrator plants, the closed loop system stability is preserved for all values of λ and for the other plants, an appropriate range in terms of λ is obtained. The optimum value of λ to attain a minimum integral square error performance index in the presence of the control signal constraints is achieved. The numerical simulations demonstrate the benefits of the Legendre based PID controller.

Stability analysis and control synthesis of uncertain Roesser-type discrete-time two-dimensional systems

We study the stability analysis and control synthesis of uncertain discrete-time two-dimensional（2D） systems.The mathematical model of the discrete-time 2D system is established upon the well-known Roesser model,and the uncertainty phenomenon,which appears typically in practical environments,is modeled by a convex bounded（polytope type） uncertain domain.The stability analysis and control synthesis of uncertain discrete-time 2D systems are then developed by applying the Lyapunov stability theory.In the processes of stability analysis and control synthesis,the obtained stability/stabilzaition conditions become less conservative by applying some novel relaxed techniques.Moreover,the obtained results are formulated in the form of linear matrix inequalities,which can be easily solved via standard numerical software.Finally,numerical examples are given to demonstrate the effectiveness of the obtained results.

Maximum two-dimensional (u×v,4,1,3)-OOCs

Let Ф（u ×v, k, Aa, Ac） be the largest possible number of codewords among all two- dimensional （u ×v, k, λa, λc） optical orthogonal codes. A 2-D （u× v, k, λa, λ）-OOC with Ф（u× v, k, λa, λc） codewords is said to be maximum. In this paper, the number of codewords of a maximum 2-D （u × v, 4, 1, 3）-OOC has been determined.

Analysis of the regional spectral properties in northwestern South China Sea based on an empirical orthogonal function

This study presents an analysis of the spectral characteristics of remote sensing reflectance(Rrs)in northwestern South China Sea based on the in situ optical and water quality data for August 2018.Rrswas initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole Rrs were characterized using the empirical orthogonal function(EOF)analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95%of the variances of Rrs are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of Rrs(A-D Rrs-EOF1)significantly contributed to the total variances of each Rrs class.In addition,the correlation coefficients between the amplitude factors of class A-D Rrs-EOF1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class ARrs-EOF1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B Rrs-EOF1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(ag(λ)),whereas the spectral shape of class C Rrs-EOF1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D Rrs-EOF1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.

Generation of transient chaos from two-dimensional systems via a switching approach

A new approach of generating transient chaos from two-dimensional（2D） continuous autonomous systems within finite time is presented.Based on an absolute-value switching law,the phenomenon of transient chaos takes place by switching between three 2D systems.Basic dynamic behavior of the systems is investigated.Numerical examples illustrate the validity of the results.

Numerical solutions of two-dimensional nonlinear integral equations via Laguerre Wavelet method with convergence analysis

In this paper,the approximate solutions for two different type of two-dimensional nonlinear integral equations:two-dimensional nonlinear Volterra-Fredholm integral equations and the nonlinear mixed Volterra-Fredholm integral equations are obtained using the Laguerre wavelet method.To do this,these two-dimensional nonlinear integral equations are transformed into a system of nonlinear algebraic equations in matrix form.By solving these systems,unknown coefficients are obtained.Also,some theorems are proved for convergence analysis.Some numerical examples are presented and results are compared with the analytical solution to demonstrate the validity and applicability of the proposed method.

Infrared Image Small Target Detection Based on Bi-orthogonal Wavelet and Morphology

An image multi-scale edge detection method based on anti-symmetrical bi-orthogonal wavelet is given in theory. Convolution operation property and function as a differential operator are analyzed,which anti-symmetrical bi-orthogonal wavelet transform have. An algorithm for wavelet reconstruction in which multi-scale edge can be detected is put forward. Based on it, a detection method for small target in infrared image with sea or sky background based on the anti-symmetrical bi-orthogonal wavelet and morphology is proposed. The small target detection is considered as a process in which structural background is removed, correlative background is suppressed, and noise is restrained. In this approach, the multi-scale edge is extracted by means of the anti-symmetrical bi-orthogonal wavelet decomposition. Then, module maximum chains formed by complicated background of clouds, sea wave and sea-sky-line are removed, and the image background becomes smoother. Finally, the morphology based edge detection method is used to get small target and restrain undulate background and noise. Experiment results show that the approach can suppress clutter background and detect the small target effectively.

基于高频正交方波注入法的永磁同步电机控制研究

针对传统高频注入法解调过程复杂和观测精度受非理想因素时延影响的不足,提出一种基于高频正交方波注入法的零低速位置估计方法。首先,考虑估计旋转轴系注入的低可靠性,选择将高频信号注入静止轴系,采用简单代数运算提取出高频响应电流,通过解调正向虚拟高频响应电流初步估计转子位置;然后,针对主要非理想因素进行影响分析,在此基础上,通过解调负向虚拟高频响应电流提取出相位滞后角,完成补偿;最后,为避免启动阶段位置收敛错误,通过获取电感变化趋势判断出磁极极性。实验结果表明,所提算法在各类工况均能稳定收敛,且最大平均误差不超过1°,说明了算法的抗扰性以及准确性。

单组分电炉镍渣基地聚物修补材料制备与性能调控

为利用具有潜在活性的固体废弃物电炉镍渣,制备单组分电炉镍渣基地聚物修补砂浆.基于正交实验和极差分析,通过掺入掺合料并改变碱模数和碱当量等关键影响因素,对地聚物砂浆各项修补性能进行调控,获取满足修补性能的最优配合比,确定各因素对修补性能的影响主次.结果表明,最优配比是矿渣掺量为30%,粉煤灰掺量为30%,碱模数为1.2,碱当量为6.5%,其28 d抗压、抗折强度分别为90.29、9.23 MPa,干燥收缩率为0.56×10-3,14 d拉伸粘结强度为3.64 MPa,满足修补砂浆规范要求.经比较,矿渣掺量对修补砂浆性能调控影响最为显著.

烟标二维码等级影响因素及其质量控制研究

目的解决烟草包装上二维码质量控制的问题,为二维码的质量控制提供技术支持。方法设计正交实验,利用方差分析法确定影响二维码质量等级的关键生产参数,并使用多元线性回归算法建模二维码质量。结果发现在生产中二维码的符号反差、固有图形污损、调制比的评级最不稳定,是质量控制的关键;不同基底表面能对墨滴扩散产生影响,建立了调制比和固有图形污损的质量预测模型。结论强调评级参数及其影响因素对质量控制的重要性,利用建模算法实现二维码质量控制,并指出质量预测模型对支持二维码的质量控制具有重要意义。

多因素影响下巷道围岩稳定性分析及优化设计研究

针对深部煤层巷道矿压显现剧烈且巷道变形难以控制的问题,基于Kastner公式对巷道高宽比、侧压系数、埋深、断面形状、围岩强度5种影响巷道围岩稳定性的因素展开正交数值模拟实验,通过方差和直观分析图法研究了各因素对巷道变形破坏的敏感性。采用平面弹性复变函数理论分析了不同侧压系数与巷道高宽比下椭圆和矩形巷道围岩的应力分布规律,对椭圆形和矩形巷道宽高比和形状进行了优化设计。研究结果表明:围岩强度与侧压系数是影响巷道围岩稳定性的主要因素,埋深、断面形状、巷道高宽比为次要因素;椭圆形巷道在等轴应力比下围岩应力差值最小;矩形巷道宽度为5 m、高宽比为0.6左右时,应力集中程度较小;针对矩形巷道应力快速增高区,在考虑承压特性和断面利用率的基础上设计了圆角矩形优化巷道,确立了圆角半径的计算公式,通过数值模拟验证了其良好的性能。

面向主动探测式保护的变流器正交控制策略

为避免主动探测式保护的变流器附加控制策略与原有基础控制策略之间相互干扰,提出了一种正交控制的方法。首先分析了新型电力系统中变流器的基础控制策略,针对空间矢量脉宽调制采用正序分量计算空间矢量的特点,设计了基于负序分量的附加控制策略,保证基础控制系统、附加控制系统相互解耦。其次利用基础和附加控制策略处理后的不同信号频带,引入前置滤波环节,给出了常规应用场景下的正交控制策略;然后研究了脉冲信号的生成方式,分析了附加控制策略的适用场景;最后分析了探测信号生成对一次系统和传统保护的影响。

C/C复合材料超声辅助磨削孔加工质量控制研究

为提高C/C复合材料孔加工出口边缘表面质量,以孔出口损伤因子S_(d)值(孔出口端面损伤面积与加工后理想孔面积之比)作为孔出口质量评价指标,利用单因素及正交试验方法优化磨削工艺参数,分析孔出口边缘磨削机理并提出孔出口损伤抑制策略。结果表明,当主轴转速为12000~14000 r/min,进给速度为5~7 mm/min,超声波振幅为8~9μm时,可将S_(d)值控制在4.723×10^(-3)以内。采用孔损伤抑制策略后,S_(d)值可进一步降低61.6%。此外,C/C复合材料在超声辅助磨削加工下的S_(d)值随主轴转速和超声波振幅的增加先减小后增大,随进给速度的增加逐渐增大;在保证进给速度最优时,适当提高主轴转速及超声波振幅有助于改善孔出口表面质量,并可提高加工效率。采用在临近孔出口时降低进给速度、使用刀具侧壁对孔出口进行光磨及在工件下方加设辅助支撑的策略可进一步降低孔出口损伤。

高时空分辨率自动站温度观测资料自主质量控制研究

中国地面自动站观测系统的建设日趋完善,目前已建成六万多个自动气象观测站点。严格的质量控制是自动站资料有效应用的前提条件,然而如何分辨高分辨率自动站资料中的局地小尺度天气信息和错误资料导致的局地变化特征一直是自动站质量控制的难点。本研究在分析地面温度空间尺度特征和误差分布特征的基础上,建立了仅依赖观测资料的EOF(Empirical Orthogonal Function)地面温度观测质量控制方法。研究利用2022年1月和5月的地面自动站温度观测资料,进行了质量控制试验,并对比了质量控制前后自动站观测资料和CRA40(CMA's global atmospheric Re-Analysis)资料中的地面气温差异特征。结果表明:建立的观测资料自主质量控制方法可以有效地识别错误观测资料,很好地避免了背景场误差、陡峭地形和局部天气变化对质量控制的影响,质量控制后的自动站温度与CRA40资料的地面温度差异明显减小,空间相关性也有明显提高,证明质量控制能够有效剔除错误资料并提高自动站资料的空间连续性。

航天器姿态受限的协同势函数族设计方法

提出一种考虑航天器姿态约束的协同势函数设计方法,在姿态全局收敛的同时,保证姿态在机动过程中始终满足姿态约束.首先,建立航天器姿态指向约束模型,并针对每一个指向约束设计软约束区域;然后,基于“角度扰动”方法设计协同势函数族;接着,通过设计协同势函数族内函数切换规律,在软约束区域内构建满足姿态约束的势函数,并给出区域内势函数临界点分布的调整方法;最后,将所得的势函数用于航天器的避障控制,以比例-微分控制为例,通过数值仿真,验证该方法的有效性.

马鞍形蒙皮拉形工艺参数仿真优化与试验验证

对某马鞍形蒙皮零件在拉形过程中的起皱和破裂现象进行了研究,以得到消除缺陷的方法。采用作图法,对该蒙皮零件进行了工艺性分析,确定了工艺参数的范围,用正交试验方法设计了数值模拟方案,利用AI-FORM软件拉形模块进行了模拟仿真,并对仿真结果进行了评估,确定了一种最优的方案,并再次进行了有限元仿真验证,最后在拉形机上进行了拉形试验。发现试验结果与有限元仿真结果吻合很好,消除了起皱和破裂等缺陷,提高了零件的成形质量。结果表明,对此蒙皮零件,拉形轨迹前部分采用较大伸长率,拉伸到4.9%,后部分采用较小伸长率,最终拉伸到7%,有利于避免起皱和破裂。另外,相较于FormCAM,AI-FORM在起皱模拟方面具有明显优势。

基于正交试验的锂渣基可控低强度材料配合比研究

本文以锂渣为主要原料,制备可控低强度材料(CLSM)。以单因素试验为基础,通过正交试验探索了水泥掺量、水胶比和减水剂掺量三个因素对锂渣基CLSM的抗折强度、抗压强度、流动度和泌水率的影响。研究表明,在大掺量锂渣的CLSM体系中,水胶比和减水剂掺量对材料流动性和泌水率具有显著影响,水泥掺量对泌水率几乎没有影响,提高水泥掺量会显著增加CLSM的抗压强度和抗折强度。对比各个因素对CLSM的影响,满足CLSM性能指标要求的胶凝材料适宜配合比为水泥掺量12%(质量分数,下同)、锂渣掺量88%、水胶比0.57、减水剂掺量0.20%。此时CLSM的流动度为231 mm,泌水率为1.49,28 d抗折强度可达1.74 MPa, 28 d抗压强度为4.90 MPa,各项指标优良。