On-line determination of supersaturation of a kcl-nacl aqueous solution based on density measurement

A method is developed for the calculation of the saturation temperature of a KCI-NaCI aqueous solution, based on the measurement of the density and temperature of a sample solution, and prior knowledge of the NaCl concentration. Experimental density and solubility data for solutions saturated with KCI in the temperature range of 299 to 321 K with concentrations of NaCl greater than 0.200 kg/kg H₂O were used to develop the empirical correlation allowing the calculation of the solution saturation level. The method is applicable in the on-line determination of the level of supersaturation in a KCI crystallizer in which the NaCl concentration is known. Knowledge of the prevailing supersaturation is necessary for the control of crystal purity and crystal size distribution in industrial potash crystallizers.     

Mixed H2/H∞ robust model predictive control with saturated inputs

In this paper, we investigate the mixed H₂/H_∞ robust model predictive control (RMPC) for polytopic uncertain systems, which refers to the infinite horizon optimal guaranteed cost control (OGCC). To fully use the capability of actuators, we adopt a saturating feedback control law as the control strategy of RMPC. As the saturating feedback control law can be effectively represented by the convex hull of a group of auxiliary linear feedback laws, the auxiliary feedback laws allow us to design the actual feedback control law without consideration of the input constraints directly to achieve the improved performance. Moreover, we suggest the relative weights on the actual and auxiliary feedback laws to the RMPC, which in turn improves the closed-loop system performance. Furthermore, an off-line design of the proposed RMPC is also developed to make it more practical. Numerical studies demonstrate the effectiveness of the proposed algorithm.     

Development of soft sensor by incorporating the delayed infrequent and irregular measurements

Originated from challenging industrial applications, this paper addresses a soft sensor development problem for linear systems with two types of measurements. One is fast, regular and delay-free measurements. The other is infrequent, irregular measurements with time-varying delays. The approach to be taken is based on the Kalman filter and data fusion technique, avoiding running the full augmented state Kalman filter, and leading to a considerably lower implementation cost. Although it is suboptimal, the loss in performance is minor compared to the optimal filter. Two simulation examples demonstrate the advantages of the proposed approach. An industrial soft sensor application example is also used to demonstrate its practicality.     

A multi-fluid nonrandom lattice fluid model: General derivation and application to pure fluids

A multi-fluid nonrandom lattice fluid model with no temperature dependence of close packed volumes of a mer, segment numbers and energy parameters of pure systems is presented. The multi-fluid nonrandom lattice fluid (MF-NLF) model with the local composition concept was capable of describing properties for complex systems. However, the MF-NLF model has strong temperature dependence of energy parameters and segment numbers of pure systems; thus empirical correlations as functions of temperature were represented for reliable and convenient use in engineering practices. The MF-NLF model without temperature dependence of pure parameters could not predict thermodynamic properties accurately. It was found that the present model with three parameters describes quantitatively the vapor pressure and the saturated density for the pure fluid.     

输入受限线性系统鲁棒抗饱和控制

针对抗饱和控制的鲁棒性问题,将研究扩展到对输入饱和非线性、时变参数和动态不确定性具有结构摄动的鲁棒性框架内,给出了一种线性时不变系统鲁棒抗饱和控制算法.鉴于积分二次型约束具有刻画结构不确定性的能力,选择在积分二次型约束框架下解决问题.以定标的线性矩阵不等式形式给出了系统分析和控制综合条件.飞行控制仿真结果说明此算法不仅可以成功克服饱和非线性,且对时变参数和动态不确定性具有良好的鲁棒性.     

钕掺杂钛酸钡陶瓷材料的制备及电阻-温度依存性的研究

讨论了稀土元素钕(Nd)对钛酸钡陶瓷材料的微观结构和介电性能的影响,以BaCO3、Nd2O3和TiO2为原材料采用固相法贮备了掺杂钕的BaCO3、TiO2纳米粉体,并经高温烧结后得到(Ba1-xNdx)Ti1-x/4O3基片,并对其进行测试,研究了钕掺杂对钛酸钡陶瓷电阻-温度依存性.     

积极引导新社会阶层有序参政议政的思考

改革开放30年来中国社会结构发生的最大变化是新社会阶层的形成。随着社会主义市场经济体制的初步建立,新社会阶层的队伍不断壮大,使中国经济、社会的影响力也越来越大,并在政治舞台上渐渐有了一席之地。人们参政愿望的强烈、自身素质的提高以及参政过程中存在的不同程度的问题,为新社会阶层有序参政提供了可能性和必要性,而执政党的积极引导则成为新社会阶层有序参政议政的领路航标。     

启发式探索的协议测试序列生成

为避免可达性分析方法生成协议测试序列状态过程中爆炸问题的出现,提出了一种启发式探索协议状态格局空间的可执行测试序列生成算法. 该算法采用权值扩展有限状态机建模被测协议,以启发式状态格局探索策略替代传统的宽度优先搜索方式生成可执行协议测试序列;把协议可执行测试序列生成转化为在协议状态格局空间中探寻最小权值路径的问题. 实验数据表明,与宽度优先可达性分析方法相比,新算法具有较好的时空特性.     

带有检测迟延的燃料-汽压系统状态观测器设计

由于时延现象的大量存在,时延系统的状态估计问题得到了广泛的研究和重视.针对输出含有时间延迟的燃料-汽压系统,进行了时间延迟补偿观测器的设计.针对不同的时间延迟进行了仿真,实验结果表明,观测器在一定的时间内能够很好地跟踪输出时延系统的状态.