Observer design for nonlinear discrete‐time systems: Immersion and dynamic observer error linearization techniques

This paper focuses on the observer design for nonlinear discrete‐time systems by means of nonlinear observer canonical form. At first, sufficient and necessary conditions are obtained for a class of autonomous nonlinear discrete‐time systems to be immersible into higher dimensional observer canonical form. Then a method called dynamic observer error linearization is developed. By introducing a dynamic auxiliary system, the augmented system is shown to be locally equivalent to the generalized observer form, whose nonlinear terms contain auxiliary states and output of the system. A constructive algorithm is also provided to obtain the state coordinate transformation. These results are an extension of their counterparts of nonlinear continuous‐time systems to nonlinear discrete‐time systems (Syst. Control Lett. 1986; 7 :133–142; SIAM. J. Control Optim. 2003; 41 :1756–1778; Int. J. Control 2004; 77 :723–734; Automatica 2006; 42 :321–328; IEEE Trans. Automat. Control 2007; 52 :83–88; IEEE Trans. Automat. Control 2004; 49 :1746–1750; Automatica 2006; 42 :2195–2200; IEEE Trans. Automat. Control 1996; 41 :598–603; Syst. Control Lett. 1997; 31 :115–128). Copyright © 2009 John Wiley & Sons, Ltd.     

多版本技术中相同操作的处理策略

意愿保证是协同编辑系统中的关键问题之一,其研究具有挑战性.多版本技术通过对象复制策略有效地解决实时协同图形编辑系统中的冲突操作的意愿保证问题.本文分析了编辑中一类重要操作--相同操作在多版本技术及其对象标识中存在的问题,提出了一个对象版本标识解决方案和相关的策略,并讨论了相同操作对操作历史日志的维护的影响和改进.实验表明,本文提出的方法有效地完善了多版本技术中对不同操作的处理.     

Separation results for the stabilization of nonlinear systems using different high-gain observer designs

High-gain observers have been used in the design of output feedback controllers due to their ability to robustly estimate the unmeasured states while asymptotically attenuating disturbances. The available techniques for the design of high-gain observers can be classified into three groups: pole-placement algorithms, Riccati equation-based algorithms, and Lyapunov equation-based algorithms. In [1], we presented separation results for globally bounded stabilizing state feedback controllers when the high-gain observer is designed using pole-placement so as to create a closed-loop system with two-time-scale structure. In this paper, we show that the separation results of [1] hold for the other observer designs.     

Recursive nonlinear observer design: beyond the uniform observability

We propose a recursive design scheme of a state observer for multiple-input-multiple-output, partly lower triangular nonlinear systems. The design begins from the subdynamics far from the output and propagates to the subdynamics close to the output, recalling the backstepping scheme for nonlinear control. The proposed class of systems is fairly general since it includes nonuniformly observable and/or detectable multioutput systems. Error convergence to zero is proved assuming boundedness of inputs a posteriori (i.e., after the design), which is preferable whereas most results in the literature assume the boundedness; a priori (i.e., before the design). A global observer is proposed with the global Lipschitz condition of the system, but without any restriction on the size of Lipschitz coefficient. The Lipschitz condition can be removed when a semiglobal observer is of interest.     

Computational observer design techniques for linear systems withunknown inputs using the concept of transmission zeros

Computational observer design techniques for linear systems subject to unknown inputs are presented. Complete and intuitive geometric conditions for the solution of the problem which result in design matrix equations are provided. These design equations are solved in a computationally efficient way. The synthesis of the reduced-order observer takes full advantage of the concept of transmission zeros. In particular, the necessary and sufficient conditions obtained are given in terms of the transmission zeros of the triple (A,D, C)     

FPGA-based architecture to estimate the input glucose in a dark fermenter using a super-twisting observer

This article presents a digital architecture design for a Super-Twisting Observer (STO) implemented in a Field-Programmable Gate Array (FPGA). The STO is robust in the presence of uncertainties, which makes it suitable to estimate unknown inputs present in biological systems and applications based on sensorless control accurately. The proposed STO is used to estimate the glucose concentration in the inflow of a hydrogen production bioreactor (e.g., dark fermenter). The dark fermenter is not generally recognized as a swift process. Therefore, the observer digital architecture design criteria aim to optimize hardware resources and reduce power consumption through an iterative approach to perform internal arithmetic operations efficiently. Besides, an analysis of the errors produced by internal operations, observer discretization, and fixed-point data representation is presented and discussed. Numerical results showed that embedding the super-twisting observer into the FPGA is a reliable, low-power consumption, and efficient alternative to estimate the input glucose in a dark fermenter.     

Q-Automata: Modelling the Resource Usage of Concurrent Components

Q–automata are introduced to model quality aspects of component-based software. We propose Q-algebras as a general framework that allows us to combine and choose between quality values. Such values are added to the transitions of automata, which represent components or channels. These automata can be composed by a product construction yielding a more complex Q-automaton labelled with the combined costs of its components. Thus we establish compositionality of quality of service based on an algebra of quality attributes associated with processes represented by automata.     

Rendezvous facilities: Concurrent C and the Ada language

The concurrent programming facilities in both Concurrent C and the Ada language are based on the rendezvous concept. Although these facilities are similar, there are substantial differences. Facilities in Concurrent C were designed keeping in perspective the concurrent programming facilities in the Ada language and their limitations. Concurrent C facilities have also been modified as a result of experience with its initial implementations. The authors compare the concurrent programming facilities in Concurrent C and Ada and show that it is easier to write a variety of concurrent programs in Concurrent C than in Ada     

Implementing design patterns as parametric aspects using ParaAJ: The case of the singleton,observer, and decorator design patterns

Implementation of a design pattern can take many forms according to the programming language being used. Most of the literature presents design patterns in their conventional object-oriented implementations. Several other studies show the implementation in aspect-oriented languages such as AspectJ, EOS, and Caesar. In this work, we compare the implementation of three design patterns: singleton, observer, and decorator design patterns in these languages and also discuss the possibility of implementing them in ParaAJ: an extension to the AspectJ language that implements the idea of parametric aspects. We found that ParaAJ helps in making the implementation of the singleton and observer patterns reusable but it fails to help in the decorator case. The problem with the decorator pattern exists because of the current translation mechanism of ParaAJ׳s aspects to normal AspectJ׳s aspects. This opens the door for further work in ParaAJ to better support the idea of parametric aspects.     

Concurrent engineering: The manufacturing philosophy for the 90''s

Concurrent Engineering (CE) has recently been recognized as a more integrated approach to develope high quality products and bringing them to highly competitive global market at lower price and in significantly less time. In the past few years, an increasing effort has been made to understand and implement the principles of CE. However, there has been insufficient attempt to document these principles systematically. This paper examines the subject of CE and the ongoing studies which emphasize its various functions. A summary is presented and the projection of possible future research is discussed.     

Telepresence, soundscapes and technological expectation: putting the observer into the equation

In an experiment exploring the impact of sound on sensations of telepresence, 126 participants watched a video clip using either headphones or speakers. The results illustrate that sound is an important factor in stimulating telepresence responses in audiences. Interactions between soundscape and screen size were also revealed. A traverse interaction between aural/visual congruency and soundscapes was evident. A second data set of 102 participants was collected to illuminate the effect of technological expectation that emerged in the first study. Expectations had been mentioned in other studies, and the data support the notion that people have an expectation of the technological quality of a presentation. The results suggest that examining expectations could assist in future conceptualizations of telepresence.     

Concurrent programming in the Ada® language: The polling bias

The rendezvous is an important concept in concurrent programming—two processes need to synchronize, i.e. rendezvous, to exchange information. The Ada programming language is the first programming language to use the rendezvous as the basis of its concurrent programming facilities. Our experience with rendezvous facilities in the Ada language shows that these facilities lead to and encourage the design of programs that poll. Polling is generally, but not always, undesirable because it is wasteful of system resources. We illustrate and examine the reasons for polling bias in the Ada language. We give suggestions on how to avoid polling programs, and suggest changes to the rendezvous facilities to eliminate the polling bias. The ramifications of these changes to the implementation of the Ada language are also discussed. Although we have focused on the rendezvous facilities in the Ada language our analysis is also applicable to other languages. A polling bias can occur in any concurrent programming language based on the rendezvous mechanism if it does not provide appropriate facilities.     

Forward Observer system for radar data workflows: Big data management in the field

There are unique challenges in managing data collection and management from instruments in the field in general. These issues become extreme when “in the field” means “in a plane over the Antarctic”. In this paper we present the design and function of the Forward Observer a computer cluster and data analysis system that flies in a plane in the Arctic and Antarctic to collect, analyze in real time, and store Synthetic Aperture Radar (SAR) data. SAR is used to analyze the thickness and structure of polar ice sheets. We also discuss the processing of data once it is returned to the continental US and made available via data grids. The needs for in-flight data analysis and storage in the Antarctic and Arctic are highly unusual, and we have developed a novel system to meet those needs.We describe the constraints and requirements that led to the creation of this system and the general functionality which it applies to any instrument. We discuss the main means for handling replication and creating checksum information to ensure that data collected in polar regions are returned safely to mainland US for analysis. So far, not a single byte of data collected in the field has failed to make it home to the US for analysis (although many particular data storage devices have failed or been damaged due to the challenges of the extreme environments in which this system is used).While the Forward Observer system is developed for the extreme situation of data management in the field in the Antarctic, the technology and solutions we have developed are applicable and potentially usable in many situations where researchers wish to do real time data management in the field in areas that are constrained in terms of electrical supply.     

On the Barbalat lemma extension for the generalized conformable fractional integrals: Application to adaptive observer design

The Barbalat-type lemma for the generalized conformable fractional-order derivative is examined in this work. An adaptive observer design is presented as an application to validate such proposed theory.     

用ASP.NET实现Web与数据库连接的技术分析

ASP.NET是一种能结合HTML网页、ASP指令和ActiveX控件建立动态的、交互的、高效的Web服务器应用程序的技术.ASP.NET通过ADO.NET实现Web与数据库的连接.实现Web与多种数据库连接的方法.     

Rainfall estimation from infrared data using an improved version of the Auto-Estimator Technique

In order to apply a suitable procedure for now-casting application in the case of heavy precipitation events, we discuss possible improvements to the Auto-Estimator Technique (AET). The AET rain estimation technique identifies precipitating clouds by comparing two successive infrared satellite images. If the pixel in the second image is colder, then upward motion is assumed and the convective system is considered to be a precipitating cloud. If the pixel in the second image is warmer, then the convective system is likely to be in a weakening phase and no precipitation is assigned. In the case of horizontal movement of the convective system, for instance approaching and weakening, the pixel in the second image can be colder without any upward motion or rain. We propose an improvement of AET (IAET) that determines the cloud top temperature variation and the corresponding rain rate estimation, taking into account the effect of horizontal motion of clouds, obtained by optical flow techniques. Precipitation events over Sardinia during November 1999, May 2000 and June 2000 were analysed. Three-hour cumulated precipitation on one pixel size area were determined by infrared Meteosat data, using both AET and IAET. A comparison between satellite estimation and 49 corresponding ground data stations was made. Contingency tables and relative statistical indices (Bias, False Alarm Ratio, Probability of Detection, Hit Rate, Critical Success Index), and errors on 3 h precipitation (mean absolute error (MAE) and Bias) were computed. When no horizontal motion of the convective system is present, AET and IAET have the same performances. In the events of May 2000, with fast movement of the precipitation system, AET significantly overestimates the rain rate while IAET gives much better performances.