含时变滞后的不确定系统的时滞相关型鲁棒控制设计

研究含时变滞后的不确定系统的控制综合问题. 基于Lyapunov方法提出了一种含滞后补偿的鲁棒控制设计方法. 闭环稳定性条件由一组线性矩阵不等式表示. 在这些条件中给出了稳定性和滞后以及其导数之间的关系. 实例显示, 利用提供的方法所给出的结果比以往文献给出的结果保守性小.     

Performance improvement using time delays in multivariable controller design

A new controller for linear multivariable ordinary systems is suggested in which distributed delays are included in the feedback loop. A general design approach to obtain this type of controller is suggested. It is shown that the resulting closed-loop system is asymptotically stable under some sufficient conditions. Sufficient conditions are derived under which the disturbance attenuation, the robustness against parameter variations, and the time-delay stability margins are improved by the proposed controller. The state feedback tracking controller and the dual-state observer are obtained by modification of the proposed controller.     

Decolorization of alkaline TNT hydrolysis effluents using UV/H(2)O(2)

Effects of H(2)O(2) dosage (0, 10, 50, 100 and 300 mg/l), reaction pH (11.9, 6.5 and 2.5) and initial color intensity (85, 80 and 60 color unit) on decolorization of alkaline 2,4,6-trinitrotoluene (TNT) hydrolysis effluents were investigated at a fixed UV strength (40 W/m(2)). Results indicated that UV/H(2)O(2) oxidation could efficiently achieve decolorization and further mineralization. Pseudo first-order decolorization rate constants, k, ranged between 2.9 and 5.4 h(-1) with higher values for lower H(2)O(2) dosage (i.e., 10 mg/l H(2)O(2)) when the decolorization occurred at the reaction pH of 11.9, whereas a faster decolorization was achieved with increase in H(2)O(2) dosage at both pH 6.5 and 2.5, resulting in the values of k as fast as 15.4 and 26.6 h(-1) with 300 mg/l H(2)O(2) at pH 6.5 and 2.5, respectively. Difference in decolorization rates was attributed to the reaction pH rather than to the initial color intensity, resulting from the scavenging of hydroxyl radical by carbonate ion. About 40% of spontaneous mineralization was achieved with addition of 10 mg/l H(2)O(2) at pH 6.5. Efficient decolorization and extension of H(2)O(2) longevity were observed at pH 6.5 conditions. It is recommended that the colored effluents from alkaline TNT hydrolysis be neutralized prior to a decolorization step.     

Delay-Dependent Robust Stability of Stochastic Uncertain Systems with Time Delay and Markovian Jump Parameters

This paper is concerned with the delay-dependent stability for a class of stochastic uncertain systems with time delay and Markovian jump parameters. The uncertainties considered in this paper are norm-bounded and governed by the Markov process. Un like the topics in the existing literature, the stability criterion is expressed in terms of linear matrix inequalities, which can be efficiently solved by using a convex-optimization algorithm. Finally, a numerical example is given to illustrate the effectiveness of the proposed method.     

亚临界和超临界状态下甲苯-多环芳香烃体系的气液相平衡

The phase behaviors of toluene/polycyclic aromatic hydrocarbon mixture systems were investigated with a continuous-flow type apparatus at 573.2,598.2.623.2 and 648.2K,while the pressure changed from 1 tp 5 MPa,The pseudo-binary phase behaviors were predicted with the Peng-Robinson equation of state with interaction parameters between toluene and pseudo-components considered.The phase diagrams of the system have been classified following the category of phase boundary diagram models.The extraction selectivity and efficiency of toluene as a solvent was discussed by comparing with that of hexane .The prediction model for selectivity was also suggested.     

Surimi-Starch Interactions Based on Mixture Design and Regression Models

Interaction effects of starch mixtures within surimi gels were investigated by modified distance-based design and analyzed by linear and nonlinear backward regression models. Nonlinear regression model showed highly significant interaction terms of starch-surimi, starch-water, and starchstarch. The response trace plot revealed that shear stress and shear strain were quite sensitive to changes in amounts of starch components. Optimum solution with combinations of various starches, surimi, and water was provided using linear and nonlinear programming.     

Remediation of RDX-Contaminated Water Using Alkaline Hydrolysis

The objective of this study was to assess the effectiveness of alkaline hydrolysis as an alternative ex situ technology for remediating groundwater contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). Treatment in both batch reactor and continuous stirred tank reactor (CSTR) was investigated. RDX reactivity was strongly dependent on the reaction pH investigated (11–13). The batch system achieved pseudo-first-order RDX reaction rates in the range of (0.8–27.7)×10?3?min?1, corresponding to half-life periods of 17.9?to?0.5?h, respectively. In the CSTR system operated at the initial RDX concentration of 4.5×10?3?mM, 99% RDX removal was achieved with the hydraulic retention time of 2?days and the reaction pH of 11.9. Formate and nitrite were produced as the major hydrolysates in the CSTR system, indicating a simultaneous reaction mechanism involving RDX ring cleavage and elimination of the ring nitrogen. The net OH? demand used only for RDX removal in the CSTR was found to be 1.5, 390, and 130?M OH?/M RDXremoved at pH values of 11.9, 11.5, and 11.0, respectively. A conceptual cost analysis indicated that the expense of alkaline treatment may be comparable to the expense of granular activated carbon treatment for long treatment periods (30?years or more), due to the potentially lower annual operational cost of alkali treatment.     

Effect of preheating on the mechanical properties of tough pitch copper made from copper scraps

When hot rolled tough pitch copper is made from copper scraps, lead is intentionally or unintentionally added to the melt. The major role of this lead seems to be the removal of metallic tin by the formation of PbO–SnO₂. A continuously cast and hot rolled copper rod was preheated at temperatures between 673–1173 K for 1 h prior to cold drawing. The maximum diameter of the PbO–SnO₂, of 1–2 μm, was obtained by preheating at 873 K. This preheating temperature also produced the maximum decrease in the recrystallization temperature and the maximum electrical conductivity of the 89.4% cold drawn wire within the investigated experimental range. This can be attributed to a decrease in the dissolved impurity concentration due to the growth of PbO–SnO₂ particles at that temperature. The decrease in recrystallization temperature enhanced the room temperature multiple upset weldability. When preheated at 1173 K, Zn₂SnO₄ particles were formed, but the recrystallization temperature increased and the electrical conductivity decreased due to the dissolution of PbO–SnO₂. This revised version was published online in November 2006 with corrections to the Cover Date.