Adaptive intelligence learning for nonlinear chaotic systems

In this paper, a reinforcement learning algorithm is proposed for a class of nonlinear differential chaotic systems. The nonlinear function of the chaotic systems is assumed to be bounded but the bounds are unknown. The unknown bounds need to be on-line adjusted. An adaptive optimal (or near optimal) control input with the reinforcement signal can be obtained compared with the current adaptive control for chaotic systems. The reinforcement signal is approximated by the neural networks. Based on Lyapunov analysis theory and by using Young’s inequalities, the closed-loop system is guaranteed to be stable. Finally, the simulation results are given to illustrate the effectiveness of the approach.     

Fuzzy adaptive dynamic surface control for a single-link flexible-joint robot

In this paper, a fuzzy adaptive controller is proposed for a single-link flexible-joint robot. Fuzzy logic systems are used to approximate unknown nonlinearities, and then a fuzzy state observer is designed to estimate the immeasurable states. By combining the adaptive backstepping design with dynamic surface control (DSC) technique, a fuzzy adaptive output-feedback backstepping control approach is developed. It is proved that all the signals of the resulting closed-loop system are semiglobally uniformly ultimately bounded (SGUUB), and both the observer and tracking errors converge to a small neighborhood of the origin by appropriate choosing the design parameters. The simulation results are provided to demonstrate the effectiveness of the proposed controller. Two key advantages of our scheme are that (i)?the proposed control method does not require that the link velocity and actuator velocity of single-link flexible-joint robot be measured directly, and (ii)?the problem of ??explosion of complexity?? is avoided.     

茚三酮为显色剂分光光度法测定氨苄西林钠

采用分光光度法研究了氨苄西林钠与茚三酮间的显色反应。 确定了反应条件,建立了一种快速、简便测定氨苄西林钠的分光光度法。 实验表明,氨苄西林钠与茚三酮在pH=5.4的水溶液中,沸水浴1 h可以反应完全,产物在λmax=564 nm下,表观摩尔吸光系数为3.72×103 L/(mol·cm)。 氨苄西林钠质量浓度在10~90 mg/L范围内服从比耳定律, 相关系数为0.9981,当氨苄西林钠浓度为40 mg/L时,测定结果的相对标准偏差为1.5%(n=6),回收率在99.0%以上。     

五氧化二钒/铈改性二氧化钛催化甲醇高选择性氧化制备二甲氧基甲烷

通过溶剂热法制备Ce掺杂的TiO₂,利用等体积浸渍法制得一系列V₂O₅/Ce-TiO₂催化剂,并用于甲醇选择性氧化制二甲氧基甲烷(DMM)。 采用XRD、UV-Vis、 H₂-TPR、NH₃-TPD等技术手段对催化剂进行了表征。 结果表明,Ce掺杂改性后的TiO₂负载V₂O₅更有利于催化剂表面钒氧物种的分散,且钒氧物种主要以孤立的和聚合态的形式存在,没有形成V₂O₅晶相结构。 Ce掺杂改性后,改变了TiO₂载体与钒氧物种间的作用力,Ce掺杂量越大,钒氧物种的还原温度逐渐向高温移动,使得催化剂的氧化还原能力减弱。 Ce改性的TiO₂负载V₂O₅,Ce的改性量对催化剂的酸性质几乎没有影响,但是催化剂的酸性却随着V₂O₅负载量的增大而逐渐减弱。 当Ce和Ti的摩尔比为0.01,V₂O₅的负载量为10%所得催化剂10V/1Ce-TiO₂具有较为适宜的氧化还原性和酸性,在反应温度160 ℃时,甲醇的转化率为39.6%,DMM的选择性高达99.9%。     

碳限额与碳交易约束下制造商生产-库存控制策略

针对制造商订货、储存、生产过程中的碳排放问题,探讨了碳限额与碳交易约束下制造商生产-库存控制策略,在对碳限额与碳交易进行数学度量的基础上构建了碳限额与碳交易约束下制造商生产-库存成本模型,并通过模型分析得出有碳约束且成本最优生产量及原材料最大订货倍数以及碳限额与碳交易约束下制造商最优生产-库存策略。计算实验与算例分析表明:相比于无碳约束情形,碳限额与碳交易约束下制造商订货数量更高,而订货频率及生产批量更低,并得出三种交易价格之下,决策变量的变化趋势。     

点火条件对密闭管道内预混氢气/空气燃爆特性的影响

基于流体动力学软件Fluent,开展数值模拟,研究点火位置（距管左端壁面100、200和500 mm）、点火温度（1 000、1 500和2 000 K）和点火面积（管左端壁面处半径为50、35和20 mm的点火域）等点火条件对1 000 mm密闭管道中预混氢气/空气（H₂/air）燃爆特性的影响。研究表明:点火位置距管左端壁面越远,中间节点处温度越高,温升越快;不同点火温度下管内最高温升速率基本同步,且提高点火温度,使得燃烧反应更剧烈,能提高管内气体温升速率,但却降低管内的压力峰值;点火面积越小,预混H₂/air燃烧前期温升越快。当采用半径为35 mm的点火域和点火位置距管左端壁面100 mm的点火方式时,预混H₂/air燃爆的各项参数相对较高。不同点火条件对密闭管内气体的动能和内能的影响规律类似于其对管内气体的流速和温度的影响规律,而对涡量的影响不明显。     

Robust lag synchronization between two different chaotic systems via dual-stage impulsive control

In this paper, an improved impulsive lag synchronization scheme for different chaotic systems with parametric uncertainties is proposed. Based on the new definition of synchronization with error bound and a novel impulsive control scheme (the so-called dual-stage impulsive control), some new and less conservative sufficient conditions are established to guarantee that the error dynamics can converge to a predetermined level, which is more reasonable and rigorous than the existing results. In particular, some simpler and more convenient conditions are derived by taking the same impulsive distances and control gains. Finally, some numerical simulations for the Lorenz system and the Chen system are given to demonstrate the effectiveness and feasibility of the proposed method.     

An improved impulsive control approach to nonlinear systems with time-varying delays

A scheme for the impulsive control of nonlinear systems with time-varying delays is investigated in this paper. Based on the Lyapunov-like stability theorem for impulsive functional differential equations (FDEs), some sufficient conditions are presented to guarantee the uniform asymptotic stability of impulsively controlled nonlinear systems with time-varying delays. These conditions are more effective and less conservative than those obtained. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed method.     

A mesoscopic approach on stability and phase transition between different traffic flow states

It is understood that congestion in traffic can be interpreted in terms of the instability of the equation of dynamic motion. The evolution of a traffic system from an unstable or metastable state to a globally stable state bears a strong resemblance to the phase transition in thermodynamics. In this work, we explore the underlying physics of the traffic system, by examining closely the physical properties and mathematical constraints of the phase transitions therein. By using a mesoscopic approach, one entitles the catastrophe model the same physical content as in the Landau's theory, and uncovers its close connections to the instability of the equation of motion and to the transition between different traffic states. In addition to the one-dimensional configuration space, we generalize our discussions to the higher-dimensional case, where the observed temporal oscillation in traffic flow data is attributed to the curl of a vector field. We exhibit that our model can reproduce the main features of the observed fundamental diagram including the inverse-λ shape and the wide scattering of congested traffic data. When properly parameterized, the main feature of the data can be reproduced reasonably well either in terms of the oscillating congested traffic or in terms of the synchronized flow.     

Pd催化交叉偶联P-C键形成反应

近30年来,Pd催化交叉偶联形成P-C键的反应在药物、催化剂配体、阻燃剂和高分子材料等领域受到普遍重视。本文介绍了Pd催化交叉偶联反应形成P-C键的方法,以及利用该法制备有机膦化合物的研究进展。作为反应底物的磷亲核试剂包括亚磷酸二烷基酯、亚膦酸酯、次膦酸酯、氧化膦、伯或仲膦、三芳基膦、亚磷酸三烷基酯、膦-硅(锡)化合物和膦-硼烷复合物等,参与偶联反应的亲电试剂包括卤代烯烃、卤代芳烃、三氟甲磺酸烯基酯、三氟甲磺酸芳基酯、乙烯基硼酸酯等,并对反应机理、反应条件和反应的影响因素进行了探讨。