Progressive events in supervisory control and compositional verification

This paper investigates some limitations of the nonblocking property when used for supervisor synthesis in discrete event systems. It is shown that there are cases where synthesis with the nonblocking property gives undesired results. To address such cases, the paper introduces progressive events as a means to specify more precisely how a synthesised supervisor should complete its tasks. The nonblocking property is modified to take progressive events into account, and appropriate methods for verification and synthesis are proposed. Experiments show that progressive events can be used in the analysis of industrial-scale systems, and can expose issues that remain undetected by standard nonblocking verification.     

Distributed attitude synchronization using backstepping and sliding mode control

We consider the problem of attitude synchronization for systems of rigid body agents with directed topologies. Two different scenarios for the rotation matrices of the agents are considered. In the first scenario, the rotations are contained in a convex subset of SO(3), which is a ball of radius less than π/2, whereas in the second scenario the agents are contained in a subset of SO(3), which is a ball of radius less than π. Using a control law based on backstepping and sliding mode control, we provide distributed, semi-global, torque control laws for the agents so that the rotations asymptotically synchronize. The control laws for the agents in the first scenario only depend on the relative rotations between neighboring agents, whereas the control laws in the second scenario depend on rotations defined in a global coordinate frame. Illustrative examples are provided where the synchronization is shown for both scenarios.     

Introducing robustness in model predictive control with multiple modelsand switching

Model predictive control is model-based. Therefore, the procedure is inherently not robust to modelling uncertainties. Further, a crucial design parameter is the prediction horizon. Only offline procedures to estimate an upper bound of the optimal value of this parameter are available. These procedures are computationally intensive and model-based. Besides, a single choice of this horizon is perhaps not the best option at all time instants. This is especially true when the control objective is to track desired trajectories. In this paper, we resolve the issue by a time-varying horizon achieved by switching between multiple model-predictive controllers. The stability of the overall system is discussed. In addition, an introduction of multiple models to handle modelling uncertainties makes the overall system robust. The improvement in performance is demonstrated through several examples.     

压延的有限元解析

运用润滑近似简化了用以描述材料在压延机两辊筒间隙中的牛顿型和非牛顿型流动的一般方程。然后,用有限元法求解所得到的方程。结果跟既有的牛顿型流体的解析解具有良好的一致性。对于非牛顿型流体在对称压延和不对称压延(不同的辊径,不同的辊速)时的压力和速度分布以及压延厚度,还得到了新的结果。这一问题的解决,展示了用有限元法解决具有实用价值的流变学问题的巨大可能性,特别是对于那些具有复杂边界条件或自由表面的问题。     

强旋湍流气-固两相流动和煤粉燃烧数学模型及其在涡旋燃烧炉的应用(Ⅰ)——模型

结合新型燃煤涡旋燃烧炉的研制和冷、热态实验,建立并发展了二维强旋湍流气固两相流动和煤粉燃烧的数学模型,以此作为对涡旋燃烧炉内多相流动。传热和燃烧过程进行数值模拟和分析的基础。     

痕量工程

多年来,而且在越来越大的范围内,工程人员曾经和存在有很低浓度的物料的物系所产生的问题打交道。 有时候这些物料是污垢物,它们导致不合格的产品或危险的场面(例如,聚合物中的“鱼眼”,废气中的一氧化碳)。在别的场合,这些物料具有很高的实际价值,在经济上有理由把它们浓缩并回收(例如,从沙里回收金,重氢的生产)。     

在效果卓越的防晒及护肤产品中防晒保护的配方策略

在效果卓越的防晒及护肤产品中防晒保护的配方策略@Julian P.Hewitt @杜晶$有利凯玛亚太有限公司上海代表处!上海200030~~~~~~     

IR在胎面胶中的应用

具有高含量3，4-结构的IR能特别有效地提高高性能轮胎的湿抓着力。因此，可以通过调整炭黑和BR用量来提高轮胎的磨耗和滚动阻力性能，同时保持优异的湿抓着性能。     

电渗析流体动力学的试验研究

由于许多工业的电渗析膜是有柔性的,所以在膜与膜之间用各种型式的隔板,组成具有刚性的膜堆。但问题在于这些隔板网对流体的混和与电渗析作用有影响。若网选择得不适当,则液流有停滞区,那么就会减少液体的有效分散面积。本研究的目的是测定各种隔板对流体