基于模糊自适应PID控制器的张力控制系统

针对常规PID控制在张力控制中,控制参数难以整定的问题,设计出一种基于模糊控制原理的自适应PID控制器,根据偏差和偏差变化率来实时调整Kp、Ki、Kd参数.仿真结果显示,这种模糊自适应PID控制器比常规PID控制器在张力控制中有更好的控制特性.     

纸纱复合制袋印刷一体机张力控制器设计

目的研究纸纱复合制袋印刷一体机纸张张力控制器。方法针对纸纱复合制袋印刷一体机的张力控制问题,结合模糊自适应PID与粒子群算法,设计基于余弦自适应调整惯性权重的粒子群优化算法的模糊自适应PID张力控制器。利用余弦自适应调整惯性权重的粒子群优化算法,搜索出一组最优的PID参数,来提高张力的控制精度。结果仿真结果表明,该张力控制方法的响应时间为0.25 s,最大超调量为2%,小于其他方法的响应时间和最大超调量。结论设计的控制器与传统的PID控制和模糊自适应PID控制相比,具有响应速度快、控制输出稳定、调节时间短等优点。     

新型悬浮包装中薄膜张力的模糊自适应PID控制

目的解决新型悬浮包装缓冲衬垫生产中薄膜张力难以控制的问题。方法建立非连续覆膜环节中张力系统的数学模型,提出以Lab VIEW为仿真软件,模糊自适应PID为控制算法的仿真策略。分析在不同卷径、不同加速度和加减速方式下,薄膜张力的变化情况和算法的控制效果。结果仿真结果表明,薄膜卷径越小张力波动越大,运行加速度越大薄膜张力波动越大。在不同工况下,模糊自适应PID较常规PID有更快的响应速度和更小的超调量。结论模糊自适应PID参数调整简单,适应性好,能满足非连续覆膜过程中薄膜张力稳定的控制要求。     

卷筒料印刷装备收卷张力系统解耦控制研究

目的 为了保证卷筒料印刷装备收卷张力系统的性能,提出一种适用于收卷张力系统的自抗扰（ADRC）解耦控制器。方法 在收卷张力系统数学模型基础上,结合卷筒料收卷系统的工作原理,基于ADRC控制技术设计收卷张力系统的ADRC解耦控制器,并利用Simulink软件对所提出的控制策略进行仿真研究。结果 在相同的阶跃输入下,研究结果表明,PID控制器调整时间为2.4 s,而ADRC解耦控制器调整时间为0.7 s;在PID控制下,收卷基材张力出现超调和震荡,而在ADRC解耦控制下,基材张力无超调和震荡现象;采用PID控制器,收卷牵引跨度张力变化引起收卷跨度张力波动,而采用ADRC控制器则没有波动。结论 提出的卷筒料印刷装备收卷张力系统ADRC解耦控制器实现了高精度张力控制,具有比传统PID控制器更好的控制性能。     

基于MATLAB的专家整定PID控制系统设计与仿真

针对在复杂系统中实现在线整定参数的PID控制问题 ,介绍了一种基于专家系统的自整定PID控制系统设计方案 ,同时利用MATLAB中的SIMULINK和控制系统工具箱进行了仿真研究 ,仿真结果表明 ,专家整定PID控制系统比常规PID控制器(控制参数固定 )控制效果好     

HTF58X2注塑机螺杆筒温度的模糊PID控制

分析了HTF58X2注塑机螺杆筒温控系统的特点与要求。考虑到传统PID控制器中的螺杆筒温控系统因具有非线性、纯滞后、时变性而难以取得满意的温控效果,提出了一种基于模糊策略的PID参数在线整定的自适应控制器。该控制器根据现场输入的温度偏差和偏差变化率,通过模糊推理对PID控制器参数进行在线调整,以适应不同工况下PID参数的最佳匹配。Matlab/Simulink仿真和实验测试的结果表明,模糊-PID控制器与固定参数的PID控制器相比,在调节速度、超调量和自适应能力等方面具有一定的优势。     

煤矿凿岩机器人模糊自适应PID控制策略研究

在现有PID控制器的基础上,利用模糊推理实现了对PID参数在线自整定模糊自适应控制,并且在Matlab仿真软件下将该控制器在机器人钻臂控制系统中的应用进行了仿真研究,仿真结果表明,参数自适应模糊PID控制器能使系统达到满意的控制效果,提高了钻臂的定位精度。     

卷筒纸印刷机纸带磁粉制动张力控制优化设计

目的 优化卷筒纸印刷机纸带磁粉制动张力控制系统,降低张力控制系统响应时间、超调量、调节时间,提高系统抗干扰能力,提高纸带张力控制效果.方法 在纸带张力常规PID控制器基础上,引入制动器滞后补偿环节,利用Simulink仿真软件,设计出补偿PID控制器,分别对常规PID控制器和补偿PID控制器开展仿真分析.结果 得到常规PID控制器单位阶跃响应参数,上升时间tr=0.75 s,超调量 σ=9.5％,调节时间ts=2.812s,稳态误差es=0.001.得到补偿PID控制器单位阶跃响应,上升时间tr=0.40 s,超调量σ=6.7％,调节时间ts=1.962 s,稳态误差es=0.仿真15,10 s时引入扰动信号后,常规PID控制器在3.04 s回归稳态;补偿PID控制器在1.21 s回归稳态.结论 通过仿真分析,对比阶跃响应参数和干扰后回归速度,可知补偿PID控制器的动态性能优于常规PID控制器,控制纸带纸力性能较好,为优化卷筒纸印刷机张力控制提供了理论指导.     

包装覆膜自适应恒张力控制方法研究

目的为解决悬浮包装生产过程中薄膜张力不稳定等问题,建立覆膜过程薄膜张力数学模型。方法针对传统PID控制在薄膜张力控制中的诸多不足,基于BP神经网络设计自适应PID薄膜张力控制方法。根据系统运行状态,调节PID控制器的参数。通过神经网络的自身学习来调整权系数,确保被控对象处于稳定工作状态。为进一步优化BP神经网络控制性能,利用鱼群寻优算法实现初始阈值和权值优化。最后,进行仿真和实验研究。结果仿真和实验结果表明,基于改进BP-PID控制算法进行张力控制时,系统响应速度较快,最大超调量较小。薄膜张力的最大相对误差只有0.5N,误差值都比较小。结论改进BP-PID算法具有较高的控制精度和稳定性,可满足包装覆膜要求。     

模糊自适应PID控制在张力控制中的应用

针对凹版印刷机张力控制系统是一个非线性、强藕合、时变的复杂系统,用普通的PID难以达到理想的控制效果,设计出一种基于模糊控制原理的自适应PID控制器,根据偏差和偏差变化率来实时调整KP、KI、KD的参数.仿真结果表明,这种模糊自适应PID比常规PID控制器在张力控制中具有更好的控制性能.     

Double Punch Test to control the energy dissipation in tension of FRC (Barcelona test)

Current testing methods used to measure tensile properties of Fiber Reinforced Concrete (FRC) are mainly based on bending test of beam specimens. They normally show a considerable scatter that makes difficult the quality control, as in particular when such properties are intended to estimate the strength of structural members. In order to improve the material assessment procedure, the Double Punch Test (DPT) has been recovered for the quality control of the tension behaviour of FRC. Former experimental research showed the feasibility of the test and a reduction of the scatter in the values of the tensile strength and of the toughness. This paper describes the results of an experimental program carried out using both DPT and bending test on FRC with different type of fibers, concretes and fiber contents. In addition, a correlation between both tests is proposed. Its application to steel and polyolefin FRC specimens shows very good results.     

卷筒包装材料的张力分析

以卷筒包装材料的收放卷过程为例，分析包装机械工作过程中柔性包装材料的张力。通过变质量构件的动力学分析，得出张力控制力矩随卷筒直径变化的计算公式。此外，由于张力还受张力还受许多不确定因素的影响，其变化是一个随机过程。当统计图上出现不正常变化时，调节控制力矩需加一个附加值。     

Simulation of crack propagation of fiber reinforced cementitious composite under direct tension

Mode I crack propagation in fiber reinforced cementitious composite is simulated based on fracture mechanics criteria. To analyze crack propagation, a superposition method is employed to calculate the stress intensity factor at the crack tip resulted from both the applied load and the crack bridging stress. Using the model, the effects of various material parameters on the tensile performance are investigated. The requirements for tensile strain-hardening and multiple cracking are analyzed and possible methods for material performance optimization are discussed. Finally, predicted behavior is verified by tensile and bending tests performed on two fiber reinforced cementitious composite beams.     

Inter-relation between true stress at the onset of necking and true uniform strain in steels – A manifestation of onset to plastic instability

A linear relation is observed between the true stress at the onset of necking and true uniform strain in type 316L(N) austenitic steel and P91 ferritic steel over wide range of test conditions. The observed linear relation between the true stress at the onset of necking and true uniform strain has been rationalised in terms of the onset to plastic instability. The strain regime, over which the alloy deforms by stable plastic flow, is directly proportional to the tensile strength.     

ASTM标准与我国金属拉伸试验标准中力学性能名称和定义对照

就美国ASTM标准与我国金属拉伸试验标准中的力学性能名称和定义进行了对照和解释。     

Thermal-conductivity and tensile-properties of BN, SiC and Ge nanotubes

Thermal-conductivity and axial tension of single-wall BN (Boron Nitride), SiC (Silicon Carbide) and Ge (Germanium) nanotubes are simulated through the MD (Molecular Dynamics) method, and the conductivity-temperature and loading-strain curves of the nanotubes are given. According to the obtained results, the differences of the nanotubes in thermal-conductivity and tensile-properties are investigated. The results show that the thermal-conductivity of all the tubes decreases with the increase of temperature and diameter; at the same temperature the BN tube has the best thermal-conductivity, whereas the SiC and Ge tubes have the comparable one; the Ge tube has both the worst anti-deformation and anti-loading capability, the BN tube the best anti-deformation one, and the BN and SiC tubes the comparable anti-loading one.     

ASTM金属材料拉伸试验方法介绍

介绍了ASTM E8(E8M)标准中的金属材料屈服强度、屈服点伸长率、均匀伸长率、抗拉强度、伸长率和断面收缩率的测量方法，并与我国相应的标准试验方法进行了比较。     

Tensile Elastic Behavior of a Zr-Cu-Ag-Al Bulk Metallic Glass

Tensile elastic behavior of bulk Zr46（Cu4.5/5.5Ag1/5.5）46Al8 metallic glass was experimentally investigated. It exhibited linear and non-linear time-independent elastic deformation with a demarcative stress of approximately 500 MPa within the timescale in the present work, and repeated loading-unloading before yielding did not alter stress-strain relationship. The pure linear elastic strain limit is 0.6%, significantly lower than 2% as generally reported, but still much higher than 0.1% observed for typical crystalline alloys. Deviation from linear elastic behavior at stresses higher than 500 MPa is explained here as a macroscopic manifestation of local fluctuations in elastic strain, which becomes pronounced at stresses higher than the critical value. The occurrence of non-linear elasticity is possibly also related to the sinusoidal relationship between shear stress and atomic displacement.     

Surface Tension,Phase Separation,and Solidification of Undercooled Cobalt–Copper Alloys

By using electromagnetic levitation, liquid Cu–Co alloys can be undercooled below their liquidus temperature into the metastable miscibility gap, leading to a phase separation into a cobalt‐rich L₁ phase and a cobalt‐poor L₂ phase. This paper reports on experimental and theoretical investigations into the properties of this system, including equilibrium shape, surface, and interfacial tension, phase separation, as well as solidification behavior. Solidification experiments were performed in microgravity in order to minimize the effect of convection on the resulting microstructure.     

镍-钛合金弹性模量的测定

采用静态拉伸法和纳米压入法对具有伪弹性行为的镍-钛合金的弹性模量进行了研究.结果表明,镍-钛合金的弹性模量随其相组成的变化而变化,母相状态时的弹性模量为24.5 GPa,而马氏体相状态时的弹性模量为11.6 GPa.多次重复拉伸使其弹性模量降低并呈现非线性的变化趋势.纳米压入法测量镍-钛合金的弹性模量同拉伸法测量结果有较大的偏差,其原因同纳米压入法未考虑伪弹性变形行为有关.