A new calculation method of feedback controller gain for bilinear paper-making process with disturbance

This paper presents a new method to calculate the feedback control gain for a class of multivariable bilinear system, and also applied this method on the control of two sections of paper-making process with disturbance. The robust H∞ control problem is to design a state feedback controller such that the robust stability and a prescribed H∞ performance of the resulting closed-loop system are ensured. The controller turns out to be robust with respect to the disturbance in the plant. Utilizing the Schur complement and some variable transformations, the stability conditions of the multivariable bilinear systems are formulated in terms of Lyapunov function via the form of linear matrix inequality (LMI). The gain of controller will be calculated via LMI. Finally, the application examples of a headbox section and a dryer section of paper-making process are used to illustrate the applicability of the proposed method.     

环氧丙烷生产工艺进展

综述了近年来环氧丙烷合成工艺的新进展,包括对现有环氧丙烷生产工艺的革新、直接氧化法、光催化环氧化等方法,并对各种方法的特点和发展前景进行了讨论.     

一种降压型开关电源芯片电路的研究与设计

设计了一款PWM控制模式降压式（buck）直流一直流转换器芯片。该芯片为电压反馈控制模式,内部补偿使得反馈控制有很好的线性和很快的负载响应而无需通过外部设计。芯片采用CMSC0．5μm BCD工艺实现。PSPICE仿真结果表明,输出电压只有大约50mY的纹波,静态电流为3mA左右。输出电压在低于0．5V时,芯片具有短路降频功能,工作频率由81KHz降到23KHz左右,输出负载由0．2A跳变到2A时具有很好的负载调整率,大约为0．2％,转换效率可以达到85％以上。     

磁悬浮系统的控制方法研究

对于电磁吸浮型磁浮列车,悬浮控制是其关键部分,由于该系统的非线性和不稳定性,需要通过主动控制使其稳定悬浮。建立了磁悬浮列车悬浮系统模型,针对模型的非线性问题,采用精确反馈线性化将悬浮系统的非线性模型线性化,然后用闭环增益成形算法设计出非线性鲁棒控制器。用MATLAB的Simulink对具有扰动的非线性模型进行仿真,仿真结果表明控制效果没有静差和超调,调节时间快。     

核电厂小型承压容器泄漏率直读的可行性分析

对比气体泄漏率的精确计算值与直读值的差异,分析误差的成因并找出切实可行的缩小误差的方法,使得直读法在小型承压容器的大批量泄漏率检测中发挥了重要的作用。     

熔体直纺129dtex/144f涤纶细旦POY的生产工艺

介绍了在直接纺丝设备上,通过工艺调整与设备改进,成功开发129dtex/144f涤纶细旦POY的经验。     

Decomposition of nitric oxide over perovskite oxide catalysts: effect of CO2, H2O and CH4

Direct nitric oxide decomposition over perovskites is fairly slow and complex, its mechanism changing dramatically with temperature. Previous kinetic study for three representative compositions (La_0.87Sr_0.13Mn_0.2Ni_0.8O_3−δ, La_0.66Sr_0.34Ni_0.3Co_0.7O_3−δ and La_0.8Sr_0.2Cu_0.15Fe_0.85O_3−δ) has shown that depending on the temperature range, the inhibition effect of oxygen either increases or decreases with temperature. This paper deals with the effect of CO₂, H₂O and CH₄ on the nitric oxide decomposition over the same perovskites studied at a steady-state in a plug-flow reactor with 1 g catalyst and total flowrates of 50 or 100 ml/min of 2 or 5% NO. The effect of carbon dioxide (0.5–10%) was evaluated between 873 and 923 K, whereas that of H₂O vapor (1.6 or 2.5%) from 723 to 923 K. Both CO₂ and H₂O inhibit the NO decomposition, but inhibition by CO₂ is considerably stronger. For all three catalysts, these effects increase with temperature. Kinetic parameters for the inhibiting effects of CO₂ and H₂O over the three perovskites were determined. Addition of methane to the feed (NO/CH₄=4) increases conversion of NO to N₂ about two to four times, depending on the initial NO concentration and on temperature. This, however, is still much too low for practical applications. Furthermore, the rates of methane oxidation by nitric oxide over perovskites are substantially slower than those of methane oxidation by oxygen. Thus, perovskites do not seem to be suitable for catalytic selective NO reduction with methane.     

Dynamic output feedback control of a flexible air-breathing hypersonic vehicle via T–S fuzzy approach

By utilising Takagi–Sugeno (T–S) fuzzy set approach, this paper addresses the robust H_∞ dynamic output feedback control for the non-linear longitudinal model of flexible air-breathing hypersonic vehicles (FAHVs). The flight control of FAHVs is highly challenging due to the unique dynamic characteristics, and the intricate couplings between the engine and fight dynamics and external disturbance. Because of the dynamics’ enormous complexity, currently, only the longitudinal dynamics models of FAHVs have been used for controller design. In this work, T–S fuzzy modelling technique is utilised to approach the non-linear dynamics of FAHVs, then a fuzzy model is developed for the output tracking problem of FAHVs. The fuzzy model contains parameter uncertainties and disturbance, which can approach the non-linear dynamics of FAHVs more exactly. The flexible models of FAHVs are difficult to measure because of the complex dynamics and the strong couplings, thus a full-order dynamic output feedback controller is designed for the fuzzy model. A robust H_∞ controller is designed for the obtained closed-loop system. By utilising the Lyapunov functional approach, sufficient solvability conditions for such controllers are established in terms of linear matrix inequalities. Finally, the effectiveness of the proposed T–S fuzzy dynamic output feedback control method is demonstrated by numerical simulations.     

Feedback nonlinear discrete-time systems

In this paper, we design an adaptive iterative learning control method for a class of high-order nonlinear output feedback discrete-time systems with random initial conditions and iteration-varying desired trajectories. An n-step ahead predictor approach is employed to estimate future outputs. The discrete Nussbaum gain method is incorporated into the control design to deal with unknown control directions. The proposed control algorithm ensures that the tracking error converges to zero asymptotically along the iterative learning axis except for the beginning outputs affected by random initial conditions. A numerical simulation is carried out to demonstrate the efficacy of the presented control laws.