Analysis and design of networked control systems using the additive noise model methodology

Networked Control has emerged in recent years as a new and exciting area in systems science. The topic has many potential applications in diverse areas ranging from control of microrobots to biological and economic systems. The supporting theory is very rich and combines aspects of control, signal processing, telecommunications, and information theory. In this paper, we give a partial overview of recent developments in Networked Control with an emphasis on the additive noise model methodology. We also point to several open problems in this emerging area. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

双侧延伸端板半刚性组合节点的抗震性能(1):试验研究

与钢结构相比,相同延性下,组合结构具有较高的刚度及较好的抗火性能。因此,在地震高发区大量采用组合结构。研究了双侧延伸端板半刚性组合节点的抗震性能,对节点进行单调、循环、准静力试验,以描述这种节点的抗震性能。试验包括内节点和外节点,并提供了关于节点延性、能量耗散、退化影响的实用数据。采用这些数据构建和校验基于构件的节点模型。节点由双向弹簧组成,其中一个代表剪切板的性能,另一个代表连接的性能。模型能精确模拟节点的性能及在循环荷载下的破坏形式。     

CONTINUITY BETWEEN DISORDER AND ORDER IN THE SEQUENTIAL DEPOSITION OF PARTICLES

In previous work we pointed out that clusters of particles built through sequential quenching show increasing degrees of order as the temperature is lowered. In the low-temperature limit, a two-dimensional model system with a nondegenerate ground state would result in a perfect crystal. The opposite, high-temperature, limit corresponds to the case of random sequential addition (RSA). In the present work we study the continuous evolution from disorder to order at intermediate states using a triangular well potential to represent particle interactions. We investigate radial and bond-orientation correlation functions and the bond order parameter as measures of the degree of crystallinity of the structures up to a reduced number density of 0.65, which is close to the jamming limit of RSA.     

Regional disparities and determinants of growth in Mexico

Developing countries such as Mexico, in which profound processes of economic liberalization have taken place over the last few decades, offer fertile terrain for studies of regional disparities. Mexico has experienced a history of polarization between regions, the industrialized north and the underdeveloped south, which have seen their differences widen, exacerbated through recurrent crises and liberalization processes. This paper looks at the convergence process among regions, examining which factors might affect regional growth, tracking the evolution of single units and identifying winners and losers. The evidence shows that northern states, bordering the USA, moved from a condition that might be described as `falling-behind' prior to liberalization to that of a `winner' after that process, while southern states went from the position of `catching-up' to that of `loser'. Regional disparities in human capital would appear to be playing a decisive role in the existence of differences. The author acknowledges comments from Gilles Duranton, Henry Overman, Andrés Rodríguez-Pose, two anonymous referees, and participants in seminars in The London School of Economics and the European University Institute.     

Variable Formulation Search for the Cutwidth Minimization Problem

Many optimization problems are formulated as min–max problems where the objective function consist of minimizing a maximum value. In this case, it is usual that many solutions of the problem has associated the same value of the objective function. When this happens it is difficult to determine which solution is more promising to continue the search. In this paper we propose a new variant of the Variable Neighbourhood Search methodology to tackle this kind of problems. The new variant, named Variable Formulation Search, makes use of alternative formulations of the problem to determine which solution is more promising when they have the same value of the objective function in the original formulation. We do that in shaking, local search and neighbourhood change steps of the basic Variable Neighbourhood Search. We apply the new methodology to the Cutwidth Minimization Problem. Computational results show that our proposal outperforms previous algorithms in the state of the art in terms of quality and computing time.     

Gain scheduled controllers for dynamic systems using sector nonlinearities

In this work we explore the use of gain scheduling for the control of nonlinear systems. The nonlinear system is represented locally by uncertain linear models using sector nonlinearities representation. The uncertain linear models are then used to design a family of robust controllers. We propose a gain scheduling procedure for the problem of guaranteed transition from an actual operating condition to a desired one by constructing a pre-specified path in the state space for the system operating points. As far as we know this problem has not been addressed before. The gain scheduling control procedure given is illustrated in the context of the regulator problem with state feedback.     

Procedural solid-space techniques for modeling and animating waves

This paper presents empirical image-synthesis techniques to define, animate and visualize scenes that simulate the behavior of the open-sea surface. Wave texture, defined by noise functions is applied by means of a solid-space animation technique to generate surface animation. Wave modeling is obtained by means of the bump-mapping technique. An implementation based on the Phong model is used to determine diffuse and specular reflections. As a result of the synthesis process, a set of frames is obtained, and is then used to compose the animation.     

Communication Response Time in P-NET Networks: Worst-Case Analysis Considering the Actual Token Utilization

Fieldbus networks aim at the interconnection of field devices such as sensors, actuators and small controllers. Therefore, they are an effective technology upon which distributed computer-controlled systems (DCCS) can be built. DCCS impose strict timeliness requirements to the communication network. In essence, by timeliness requirements we mean that traffic must be sent and received within a bounded interval, otherwise a timing fault is said to occur. P-NET is a multi-master fieldbus standard based on a virtual token passing scheme. In P-NET each master is allowed to transmit only one message per token visit, which means that in the worst-case the communication response time could be derived considering that the token is fully utilized by all stations. However, such analysis can be proved to be quite pessimistic. In this paper, we propose a more sophisticated P-NET timing analysis model, which considers the actual token utilization by different masters. The major contribution of this model is to provide a less pessimistic, and thus more accurate, analysis for the evaluation of the worst-case communication response time in P-NET fieldbus networks.     

Insights into the selective sensing mechanism of a luminescent Cd(II)-based MOF chemosensor toward NACs: roles of the host–guest interactions and PET processes

Journal of Materials Science - The structural and photophysical properties of the [Cd2(H2L)2(H2O)5].5H2O (where H4L is the ligand 5,5'-((thiophene-2,5-dicarbonyl)bis(azanediyl))diisophthalic...     

Optimizing the search directions of a mixed DDM applied on cracks

Optimization and Engineering - Domain Decomposition Methods (DDM) are a set of numerical techniques that efficiently implement parallel computing for the structural analysis of large domains. This...