State estimation of dynamical systems with nonlinearities by using proportional-integral observer

In this paper the application of a PI observer technique to dynamical systems with nonlinearities is proposed. The PI observer has two feedback loops, a proportional loop and an integral loop of the estimation error. In this way the PI observer combines the structures of the practical orientated nonlinearity observer developed by the third author and the classical Luenberger observer. The structure and the estimation performance of the PI observer are discussed and analysed. The results show that the PI observer can estimate the states not only of linear systems, but also, more significantly, of systems with any arbitrary external input which appear as unknown input, nonlinearity or unmodelled dynamics. It is shown that the PI observer works with weak assumptions, which can be fulfilled by many classes of systems to be observed. Owing to the weak assumptions it can improve many observer-based technical solutions as diagnosis or control based on observers. In the paper the conditions are given and proved. The design method is declared and carried out with illustrative examples of a linear system and of a nonlinear system of a link manipulator with flexible joints. The results are good and they show the efficiency of the PI observer. In the case of nonlinear systems the advantages of ‘robustness’ and the model independency of the proposed observer scheme can be shown clearly.     

Multiband-scatterometer data analysis of forests

Abstract

The airborne multiband scatterometer DUTSCAT promises to become a useful tool for research in the field of active microwave remote sensing. The system can measure accurate σ ° values in six frequency bands simultaneously at a selected incidence angle and polarization. An evaluation of the use of this system for research in forestry, in particular the problems related with probing thick vegetation canopies, is given. The system can acquire information on the vertical distribution of backscattering. Through inversion of a multilevel model, σ ° of forests can be divided in contributions from a number of arbitrarily chosen layers ( three or four). A simple and accurate new approach for the computation of cc values for forests (or other thick vegetation covers) from scatterometer data is given and compared with the less accurate ‘ standard’ way of processing used for other types of targets.     

Controllability of linear time-invariant systems

In this paper it is shown that for any controllable linear time-invariant system, an arbitrary initial point can be driven to an arbitrary final point by means of an input, polynomial in t of degree 2k— I, with k the controllability index of the system. Also, the state trajectory is polynomial in time and of the same degree. The bound on the degree is an improvement with respect to similar results in the literature. The proof of this result is rather direct compared to the involved proof in the literature of a weaker theorem. An extension of this result considering sinusoidal inputs and state trajectories is provided.     

智能转换器可同时满足USB或插墙式电源供电需求

某OEM制造商找到我们，表示需要我们提供“智能化的”DC／DC转换器，这样他们正基于OMAP处理器以及TPS6501x电源管理器件开发的手持设备就能毫无问题地使用现有的配件、连接器和机壳了。下列介绍的解决方案采用低功耗DC／DC开关调节器解决了这一问题。通过添加某些外部组件，该部件能够解决电源连接问题，同时降低墙式电源适配器的电压，从而成功地为TPS6501x电源管理设备供电。     

Transient stability of a power system using a non-Luré-type Lyapunov function

A new viewpoint is offered on the construction of a non-Luré-type Lyapunov function for studying the dynamic behaviour of linear systems with a non-linear feedback of the ‘classical’ sector type. The approach makes it possible to show that a particular relation between the parameters defining the Lyapunov function must be satisfied in order to ensure an estimate of the attraction domain closest to the true stability boundary.     

SINGLE-MACHINE SCHEDULING WITH CONTROLLABLE PROCESSING TIMES AND EARLINESS,TARDINESS AND COMPLETION TIME PENALTIES

The paper considers the problem of scheduling nindependent and simultaneously available jobs on a single machine, where the job processing times are compressible as a linear cost function. The objective is to find an optimal permutation of the jobs, an optimal due date and the optimal processing times which jointly minimize a cost function consisting of the earliness, tardiness, completion time and compressing costs. It shows that the problem can be solved as an assignment problem.     

Comments on ‘Global stability of solutions of non-linear control systems’

It is shown here that stability results obtained in a recently published paper are not valid and where the proof of these results fails. Explicit counter-examples are discussed.     

现代等离子切割技术及其智能化

介绍了现代等离子切割发展过程,并根据实际应用对等离子切割进行分类.着重阐述等离子切割系统中使用的核心部件和他们各自的特点,包括等离子电源、CNC数控、等离子割枪枪体、以及自动调高技术.通过多年的技术革新,这些部件已经具备相当成熟的相互兼容整合的能力.在这些核心部件技术的支持下,在加工不同厚度的各种金属材料时,现代等离子切割系统都可以高效、高质地完成任务.