内模原理在转台波动力矩抑制中的应用

为了消除系统存在的周期性扰动特别是干扰力矩对系统速率平稳性能的影响,本文对基于内模原理的自适应周期性扰动抑制方法进行了研究,利用该控制策略能够较好的抑制含单一频率、多种频率和时变频率的周期性扰动.并且对扰动频率变化较快时频率估计中出现的波动现象进行了分析.该方法在测试转台模型上进行了仿真,仿真结果显示出了良好的扰动频率辨识能力和对扰动的抑制能力.     

整合营销传播理论与新广告主义革命

整合营销传播（IMC）理论在广告业界的导入并未完成中国广告传播理念的根本性转移。中国广告尚期待一场深层意义上的实践性变革,即实现从集＂销售主义＂大成的＂整合营销传播（IMC）＂到＂人文关怀与社会关怀＂相融汇的新广告范式建构,亦即本文所论及的＂新广告主义革命＂,以此完成广告传播的观念重建,最终实现从以物为本到以人为本的根本性变革。     

锅炉过热蒸汽压力控制系统设计与实现

针对工业过程中具有大惯性、大滞后和模型参数时变等特性的蒸汽出口压力系统,采用常规PID控制方法,往往无法得到满意的控制效果.为此,提出采用三自由度内模控制-模糊自适应PID算法,通过最小二乘原理辨识主蒸汽压力对象的内部模型,实现对蒸汽出口压力系统的串级控制.该控制系统融合了模糊控制、内模控制、PID控制3种方法的特点,程序设计简单,便于工业应用.通过仿真和PCS7实验表明,该方案增强了系统抗干扰能力和鲁棒性能,改善了系统的控制品质.     

Intuitive robust stability metric for PID control of self-regulating processes

Published methods establish how plant-model mismatch in the process gain and dead time impacts closed-loop stability. However, these methods assume no plant-model mismatch in the process time constant. The work presented here proposes the robust stability factor metric, RSF, to examine the effect of plant-model mismatch in the process gain, dead time, and time constant. The RSF is presented in two forms: an equation form and a visual form displayed on robustness plots derived from the Bode and Nyquist stability criteria. This understanding of robust stability is reinforced through visual examples of how closed-loop performance changes with various levels of plant-model mismatch. One example shows how plant-model mismatch in the time constant can impact closed-loop stability as much as plant-model mismatch in the gain and/or dead time. Theoretical discussion shows that the impact is greater for small dead time to time constant ratios. As the closed-loop time constant used in Internal Model Control (IMC) tuning decreases, the impact becomes significant for a larger range of dead time to time constant ratios. To complete the presentation, the RSF is used to compare the robust stability of IMC-PI tuning to other PI, PID, and PID with Filter tuning correlations.     

The setpoint overshoot method: A simple and fast closed-loop approach for PID tuning

A simple method has been developed for PID controller tuning of an unidentified process using closed-loop experiments. The proposed method requires one closed-loop step setpoint response experiment using a proportional only controller, and it mainly uses information about the first peak (overshoot) which is very easy to identify. The setpoint experiment is similar to the classical Ziegler–Nichols (1942) experiment, but the controller gain is typically about one half, so the system is not at the stability limit with sustained oscillations. Based on simulations for a range of first-order with delay processes, simple correlations have been derived to give PI controller settings similar to those of the SIMC tuning rules (Skogestad (2003) [6]). The recommended controller gain change is a function of the height of the first peak (overshoot), whereas the controller integral time is mainly a function of the time to reach the peak. The method includes a detuning factor that allows the user to adjust the final closed-loop response time and robustness. The proposed tuning method, originally derived for first-order with delay processes, has been tested on a wide range of other processes typical for process control applications and the results are comparable with the SIMC tunings using the open-loop model.     

A new control method for MIMO first order time delay non-square systems

This paper proposes a new method using internal model control (IMC) to design Smith delay compensation decoupling controller for multivariable non-square systems with transfer function elements consisting of first order + time delay. This proposed method is applied to a shell control problem in multiple-input-multiple-output (MIMO) first order plus dead time non-square systems in which the number of input variables exceeds the number of output variables, with input and output variables being 3 and 2 respectively. This method does not only dynamically compensate for shortcoming caused by static decoupling but also overcomes the impact of model error on system performance caused by model approximation and uncertainty. In other words, the design method proposed in this paper is capable of significantly improving dynamic quality and robustness of the control system as can be seen from the simulation results. Moreover, this new method is simple and easy to implement. Integral of squared error (ISE) performance criterion is employed to quantitatively evaluate the design method.     

Multivariable disturbance observer-based H2 analytical decoupling control design for multivariable systems

In this paper, an H₂ analytical decoupling control scheme with multivariable disturbance observer for both stable and unstable multi-input/multi-output (MIMO) systems with multiple time delays is proposed. Compared with conventional control strategies, the main merit is that the proposed control scheme can improve the system performances effectively when the MIMO processes with severe model mismatches and strong external disturbances. Besides, the design method has three additional advantages. First, the derived controller and observer are given in analytical forms, the design procedure is simple. Second, the orders of the designed controller and observer are low, they can be implemented easily in practice. Finally, the performance and robustness can be adjusted easily by tuning the parameters in the designed controller and observer. It is useful for practical application. Simulations are provided to illustrate the effectiveness of the proposed control scheme.     

Tuning PI controllers for stable processes with specifications on gain and phase margins

In industrial practice, controller designs are performed based on an approximate model of the actual process. It is essential to design a control system which will exhibit a robust performance because the physical systems can vary with operating conditions and time. Gain and phase margins are well known parameters for evaluating the robustness of a control system. This paper presents a tuning algorithm to design and tune PI controllers for stable processes with a small dead time while meeting specified gain and phase margins. Simulation examples are given to demonstrate that the proposed design method can result, in a closed-loop system, in better performances than existing design methods which are also based on user-specified gain and phase margins.     

Extension of IMC tuning correlations for non-self regulating (integrating) processes

The filter term of a PID with Filter controller reduces the impact of measurement noise on the derivative action of the controller. This impact is quantified by the controller output travel defined as the total movement of the controller output per unit time. Decreasing controller output travel is important to reduce wear in the final control element. Internal Model Control (IMC) tuning correlations are widely published for PI, PID, and PID with Filter controllers for self regulating processes. For non-self regulating (or integrating) processes, IMC tuning correlations are published for PI and PID controllers but not for PID with Filter controllers. The important contribution of this work is that it completes the set of IMC tuning correlations with an extension to the PID with Filter controller for non-self regulating processes. Other published correlations (not based upon the IMC framework) for PID with Filter controllers fix the filter time constant at one-tenth the derivative time regardless of the model of the process. In contrast, the novel IMC correlations presented in this paper calculate a filter time constant based upon the model of the process and the user's choice for the closed-loop time constant. The set point tracking and disturbance rejection performance of the proposed IMC tunings is demonstrated using simulation studies and a bench-scale experimental system. The proposed IMC tunings are shown to perform as well as various PID correlations (with and without a filter term) while requiring considerably less controller action.     

键合界面金属间化合物对可靠性影响的研究现状

在微电子封装过程中,键合丝被广泛应用,而键合可靠性对于产品的应用性能有着极大的影响,受到人们的广泛关注。键合丝与常用的铝焊盘之间是异质材料,在应用和服役的过程中会在界面上产生金属间化合物(IMC),对器件可靠性产生影响,同时,键合强度也与键合丝和焊盘之间的界面反应联系密切,因此了解键合丝与铝焊盘之间金属间化合物的形成与演变对键合可靠性的影响是有必要的。本文综述了Au/Al、Ag/Al和Cu/Al三种键合界面上金属间化合物的形成与演变的研究现状,并根据目前的应用状况,展望了未来的应用发展前景。