大倾角煤层俯伪斜工作面液压支架设计系统实用性分析

为解决大倾角煤层液压支架设计过程中多维受载特征被忽略、建模过程繁琐、设计周期长等问题,结合大倾角伪俯斜工作面液压支架受载特性,研发大倾角液压支架设计系统。采用运动仿真、强度测试、物理实验等综合研究方法,以ZY5000/15.5/38型大倾角煤层液压支架设计为例,根据大倾角伪俯斜采场液压支架多维受力特征建立力学模型,分析大倾角液压支架的空间受载特性,建立伪俯斜工作面液压支架顶梁、掩护梁力学线性矩阵,利用VB.NET为开发语言结合线性矩阵和SOLIDWORKS二次开发建模软件搭建液压支架设计系统,开发出良好的人机交互用户界面。研究分析表明:该系统生成下的模型液压支架顶梁前端运动轨迹范围48 mm左右,支架顶梁前端运动轨迹曲线满足双扭线特性;模型支架最大应力为146.7 MPa,远小于材料屈服的等效应力,最大变形位移也不超过0.531 mm;研制相似比为1∶5物理模型液压支架工作阻力在38 kN左右,在不同条件下测试支架顶梁、掩护梁受载特性,实验中模型支架的力学数据与系统生成的力学数据基本相符,且实验在初撑、增阻、恒阻及卸压各阶段均满足支架的运动要求及承载特性。研究结果体现了该设计系统下模型液压支架较好的适应性,对丰富大倾角煤层液压支架设计理论和指导液压支架设计生产具有一定的科学和实践意义。

风电NACA63418翼型参数化建模及优化

风力发电机的风轮气动效率与优良翼型的气动性能密切相关。以风力机传统翼型为研究对象,结合翼型参数化建模及自适应遗传算法,寻优搜索得到高性能优化翼型。比较了CST法和改进的Hicks-Henne型函数法对于NACA63418传统翼型的拟合精度,进而选用Hicks-Henne型函数法对NACA63418翼型进行参数化建模。通过自适应遗传算法和XFOIL软件耦合实现翼型气动特性的自动计算,提高翼形的设计效率,为翼型的理论设计拓宽了思路。

基于SimAM注意力机制的轴承故障迁移诊断模型

针对轴承故障在跨工况迁移诊断时,其域不变特征难以提取,易出现模型过拟合这一问题,提出了一种基于无参数注意力模块(SimAM)的轴承故障迁移诊断方法。首先,以一维卷积神经网络作为基本框架,利用自适应批量归一化(AdaBN)对各输出层进行了归一化处理,经两层卷积层和两层池化层后,对输出特征进行了随机节点失活操作;然后,利用改进后的参数化修正线性单元(PReLU)激活函数自适应提取负值输入权值系数,分别以交叉熵损失函数监督训练有标签的源域数据,以均方对数误差(MSLE)作为损失函数训练无标签的目标数据;最后,利用自制实验台数据和凯斯西储轴承公开数据对模型进行了验证,分别以不同的单一工况作为源域,其余工况作为目标域进行了迁移诊断任务研究。研究结果表明:基于SimAM的轴承故障迁移诊断方具有较好的域不变特征提取的性能,且所提特征具有较好的聚类效果;自制实验台中的平均迁移精度在89.1%以上,最高均值可达97.85%,CWRU数据集中的平均迁移精度达98.68%。该成果可为后续轴承故障由实验向工业现场的迁移诊断奠定基础。

Adaptive Backstepping Tracking Control of a 6-DOF Unmanned Helicopter

This paper presents an adaptive backstepping control design for a class of unmanned helicopters with parametric uncertainties. The control objective is to let the helicopter track some pre-defined position and yaw trajectories. In order to facilitate the control design, we divide the helicopter s dynamic model into three subsystems. The proposed controller combines the backstepping method with online parameter update laws to achieve the control objective. The global asymptotical stability(GAS) of the closed-loop system is proved by a Lyapunov based stability analysis. Numerical simulations demonstrate that the controller can achieve good tracking performance in the presence of parametric uncertainties.

An Adaptive Fuzzy Controller for Trajectory Tracking of Robot Manipulator

In this paper, an adaptive fuzzy control algorithm is proposed for trajectory tracking of an n-DOF robot manipulator subjected to parametric uncertainty and it is advantageous compared to the conventional nonlinear saturation controller. The asymptotic stability of the proposed controller has been derived based on Lyapunaov energy function. The design procedure is straightforward due to its simple fuzzy rules and control strategies. The simulation results show that the present control strategy effectively reduces the control effort with negligible chattering in control torque signals in comparison to the existing nonlinear saturation controller.

A parameter estimation based adaptive actuator failure compensation control scheme

An adaptive actuator failure compensation control scheme is developed using an indirect adaptive control method,by calculating the controller parameters from adaptive estimates of system parameters and actuator failure parameters.A key technical issue is how to deal with the actuator failure uncertainties such as failure pattern,time and values.A complete parametrization covering all possible failures is used to solve this issue for adaptive parameter estimation.A simultaneous mapping from the estimated system/failure parameters to the controller parameters is employed to make the control system capable of ensuring the desired system performance under failures,which is verified by simulation results.

Adaptive Internal Model Control of a DC Motor Drive System Using Dynamic Neural Network

This work concerns the study of problems relating to the adaptive internal model control of DC motor in both cases conventional and neural. The most important aspects of design building blocks of adaptive internal model control are the choice of architectures, learning algorithms, and examples of learning. The choice of parametric adaptation algorithm for updating elements of the conventional adaptive internal model control shows limitations. To overcome these limitations, we chose the architectures of neural networks deduced from the conventional models and the Levenberg-marquardt during the adjustment of system parameters of the adaptive neural internal model control. The results of this latest control showed compensation for disturbance, good trajectory tracking performance and system stability.

一种基于自适应屈曲装置的减隔震支座研究

为实现桥梁的抗震韧性,提出一种以往复弹塑性变形耗散地震能量的自适应屈曲装置。采用有限元法分析该装置的抗震机理及影响参数;将该装置应用于减隔震支座中,通过算例验证该类支座的抗震性能。结果表明:自适应屈曲装置的抗侧刚度随着荷载增加逐渐退化,整体柔性增强,可有效延长结构自振周期,其荷载~位移曲线呈三阶段特性,符合抗震韧性设计要求;屈曲装置的抗侧刚度随着斜杆水平倾角的增大而降低,随着斜杆截面半径的增大而增大,随着斜杆数量的增多,装置的刚度退化曲线更为平滑。基于自适应屈曲装置的减隔震支座较传统延性抗震设计更能延长结构自振周期,在多级地震作用下,该装置可自适应多级性能目标,其屈服位移谱小于水平塑性位移,装置始终处于弹性阶段,具有良好的抗震韧性及自复位能力。

混杂系统鲁棒故障诊断

在混杂系统的参数性故障诊断中,由于参数的不确定性,会导致元件标称值发生偏移,错误报警频发导致常规自适应阈值的残差评估方法鲁棒性较差。针对上述问题,引入一种在故障检测阶段增强残差决策性能的方法。基于键合图(BG)理论,使用全局解析冗余关系在并网逆变器中进行故障检测与隔离,搭建BG的线性分式变换的混合诊断键图进行参数性故障诊断,可从模型中解耦出不确定部分,减少残差评估时上述错误报警现象且与增量键合图方法进行鲁棒性对比。在20-sim软件以中点钳位型逆变器为例验证了该策略的有效性。

气候适应视角下的参数化设计研究——以城市综合体参数化建筑设计为例

人、气候环境、建筑三者之间的关系历来被人们所探讨。随着地球气候环境变化及生态资源匮乏的现象不断浮现,建筑设计如何适应气候也变得尤为重要。文章系统地对建筑气候适应性机制理论进行了探讨,在此基础上以城市综合体为例分析参数化建筑在气候适应视角下的设计步骤。首先介绍参数化建筑设计的发展及优缺点,接着通过对比气候适应性在生物和建筑中的共同点,阐述建筑的气候适应性机制,最后对气候适应视角下的参数化建筑设计的本质、意义、过程进行探讨,并结合具体案例归纳出气候适应性建筑的设计路线。

Adaptive estimation and nonlinear variable gain compensation of the contouring error for precise parametric curve following

Contour following is one of the most important issues faced by many computer-numerical-control(CNC) machine tools to achieve high machining precision. This paper presents a new real-time error compensation method aiming at reducing the contouring error caused by facts such as servo lag and dynamics mismatch in parametric curved contour-following tasks. Due to the lack of high-precision contouring-error estimation method for free-form parametric curved toolpath, the error can hardly be compensated effectively. Therefore, an adaptive accurate contouring-error estimation algorithm is proposed first, where a tangential-error backstepping method based on Taylor's expansion is developed to rapidly find the closest point on the parametric curve to the actual motion position. On this foundation, the contouring error is compensated using a proposed nonlinear variable-gain compensation method, where the compensation gain is obtained according to not only the contouring-error magnitude but also its direction variation. The stability of the system after compensation is analyzed afterwards according to the Jury stability criterion.By design of the compensator in accordance with the presented contouring-error compensation method as well as the stability analyzation result, the balance between the response speed and the contour control stability can be effectively made. Experimental tests demonstrate the feasibility of the presented methods in both contouring-error estimation and contour-accuracy improvement.Contributions of this research are significant for enhancing the contour-following performance of the CNC machine tools.

Parametric study on power capture performance of an adaptive bistable point absorber wave energy converter in irregular waves

The power capture performance of an adaptive bistable point absorber wave energy converter(WEC)in irregular waves is investigated in this paper.Based on the linear potential flow theory and Cummins equations,the equation of motion for the WEC is established in time domain.Then a parametric study is performed on the power capture performance of the WEC by considering the influences of different wave and system parameters such as the spring combination parameter,the stiffness of auxiliary springs and main springs,the original length value of the main spring,damping coefficient of the PTO systems and the significant wave height.The results show that in an irregular wave,each parameter will have a certain impact on the performance of the device.Appropriate device parameters need to be selected according to actual environmental parameters to ensure that the adaptive bistable WEC has better power capture performance than its linear and conventional bistable counterparts.

基于室内热舒适目标为导向的气候适应性可变建筑表皮生成研究——以成都地区为例

气候适应性是生物学领域概念,能够适应不断变化的气候的建筑表皮被称为智能建筑表皮,也被称为气候适应性建筑表皮。同时,通过表皮构件的动态变化,研究适应复杂气候变化的可变建筑表皮,在探索改善室内居住环境,特别是在降低建筑能耗提供新的思路和方法。本文采用Ladybug Tools工具,对成都市典型气候特征进行分析,根据气象数据制定气候适应性策略,降低公共建筑室内制冷能耗并提高夏季室内环境的舒适度。

寒地气膜体育馆天然采光性能参数化模拟研究

气膜体育馆是全民健身事业高速发展背景下逐渐兴起的新型健身场地设施。由于膜材的透光性比传统建筑围护材料强,气膜体育馆的室内光环境更容易受到外界气候条件的影响,造成使用者视觉上的不舒适,同时寒地漫长、寒冷的冬季使室内需要更多的天然光,因此探索寒地气膜体育馆的天然采光设计对改善室内空间品质具有重要意义。本文从膜材透光率、透光膜面积比、布局形式三方面对典型模型进行采光模拟分析,为后续创新研究提供参考。

一种频率信号的自适应测量法

提出了一种频率信号测量的自适应算法。采用梯度下降法构建算法模型,依据李亚普诺夫稳定性定理对该算法在待测信号非稳定条件下的渐近稳定性进行证明。分析算法中参数因子取值大小对算法性能的影响,采用动态调节策略修正参数因子,以确保该算法在输入信号稳定条件下能准确收敛到待测频率分量,有效抑制其他频率分量及噪声的干扰;在输入信号非稳定条件下,该算法能快速做出反应,迅速收敛到待测频率分量的新状态。理论分析和仿真结果均证实了该算法的正确性和有效性。

基于参数方程的小波基自适应选择

研究了小波基的参数表达问题,得到包含不同参数的小波基的两个参数方程,提出通过对参数方程中参数的搜索来实现信号的自适应小波基分解。从不同应用角度定义了评价小波基分解效果的两个适应度函数,针对适应度与参数的非线性关系,提出了一种改进的遗传算法对小波基参数方程中的参数进行搜索,同时利用适应度函数对搜索到的小波的分析效果进行评价,当适应度达到最大值时就可得到最佳小波基。利用这一算法实现了一个铣削力信号的自适应小波基分解,并与Daubechies小波的分解结果进行了对比,结果表明自适应小波基能够更充分地分离出信号中的有用信息。

板材多点成形过程的非参数模型及自适应控制

研究了三维板类件的多点成形复杂的非线性过程。将影响成形精度的诸多因素看作系统扰动,成形过程简化为离散的单输入单输出系统,得到其非参数模型。在满足一定假设条件的前提下,多点成形过程可线性化为一个带有单参数的线性时变系统;通过对系统的分析,得到了多点成形过程的闭环递推自适应控制算法。仿真结果表明,在自适应算法的逐次控制下,工件形状以较快的速度收敛到设计的目标形状,实现了对板类件多点成形这一复杂过程的有效控制。

连续时间混沌系统的参数自适应控制

研究了连续时间混沌系统的参数自适应控制，提出了关于多重参数混沌非线性系统的参数自适应控制的新方法．考虑系统参数是线性形式的自适应控制，利用Ｌｙａｐｕｎｏｖ方法证明了参数控制方程是全局渐近稳定的．

逆变器并联的自适应滑模全局鲁棒电压控制方法

针对孤岛微电网非线性负载产生的谐波电流扰动和逆变器滤波参数摄动,使得经典的比例–积分–微分电压控制器难以实现对逆变器满足精度的控制,文中设计一种自适应滑模全局鲁棒电压控制器。该控制器对逆变系统负载电流扰动和滤波参数摄动采取自适应预测,使得控制系统具备全局鲁棒性。另外,负载电流扰动的自适应预测,在保证控制系统稳定性前提下,能够实时调节输入电压控制信号的切换增益,从而限制了输出电压的抖振。仿真和实验结果表明:该策略降低了逆变系统输出电压的抖振、谐波畸变率、稳态跟踪误差以及并联逆变器之间的环流,提高了逆变系统输出电压的动态调节能力及抵御滤波参数摄动的能力。