A universal formula for stabilization with bounded controls

We provide a formula for stabilizing feedback law using a bounded control, under the assumption that an appropriate control-Lyapunov function is known. Such a feedback, smooth away from the origin and continuous everywhere, is known to exist via Artstein's Theorem. As in the unbounded-control case treated in a previous note, we provide an explicit and ‘universal’ formula given by an algebraic function of Lie derivatives. In particular, we extended to the bounded case the result that the feedback can be chosen analytic if the Lyapunov function and the vector fields defining the system are analytic.     

Asymptotic feedback stabilization: A sufficient condition for the existence of control Lyapunov functions

In this paper we study the feedback stabilization problem for a wide class of nonlinear systems that are affine in the control. We offer sufficient conditions for the existence of ‘Control Lyapunov functions’ that according to [3,23] and [28–30] guarantee stabilization at a specified equilibrium by means of a feedback law, which is smooth except possibly at the equilibrium. We note that the results of the paper present a local nature.     

Circularly orthogonal moments for geometrically robust image watermarking

Circularly orthogonal moments, such as Zernike moments (ZMs) and pseudo-Zernike moments (PZMs), have attracted attention due to their invariance properties. However, we find that for digital images, the invariance properties of some ZMs/PZMs are not perfectly valid. This is significant for applications of ZMs/PZMs. By distinguishing between the ‘good’ and ‘bad’ ZMs/PZMs in terms of their invariance properties, we design image watermarks with ‘good’ ZMs/PZMs to achieve watermark's robustness to geometric distortions, which has been considered a crucial and difficult issue in the research of digital watermarking. Simulation results show that the embedded information can be decoded at low error rates, robust against image rotation, scaling, flipping, as well as a variety of other common manipulations such as lossy compression, additive noise and lowpass filtering.     

Dynamic high-gain scaling: State and output feedback with application to systems with ISS appended dynamics driven by all States

We propose a dynamic high-gain scaling technique and solutions to coupled Lyapunov equations leading to results on state-feedback, output-feedback, and input-to-state stable (ISS) appended dynamics with nonzero gains from all states and input. The observer and controller designs have a dual architecture and utilize a single dynamic scaling. A novel procedure for designing the dynamics of the high-gain parameter is introduced based on choosing a Lyapunov function whose derivative is negative if either the high-gain parameter or its derivative is large enough (compared to functions of the states). The system is allowed to contain uncertain terms dependent on all states and uncertain appended ISS dynamics with nonlinear gains from all system states and input. In contrast, previous results require uncertainties to be bounded by a function of the output and require the appended dynamics to be ISS with respect to the output, i.e., require the gains from other states and the input to be zero. The generated control laws have an algebraically simple structure and the associated Lyapunov functions have a simple quadratic form with a scaling. The design is based on the solution of two pairs of coupled Lyapunov equations for which a constructive procedure is provided. The proposed observer/controller structure provides a globally asymptotically stabilizing output-feedback solution for the benchmark open problem proposed in our earlier work with the provision that a magnitude bound on the unknown parameter be given.     

The constituents of business interaction––generic layered patterns

In order to perform business modelling as apart of information systems development, there is a need for frameworks and methods. The paper proposes a framework for business interaction based on a language/action perspective. The framework is an architecture of five generic layers. The first layer concept is ‘business act’, which functions as the basic unit of analysis. The following four layer concepts are ‘action pair’, ‘exchange’, ‘business transaction’, and ‘transaction group’. The framework is inspired by a similar framework constructed by Weigand et al. The paper makes a critical examination of this framework as a basis for the proposed framework.     

The living in a lattice rule language

This paper presents a rule-based query language for an object-oriented database model. The database model supports complex objects, object identity, classes and types, and a class/type hierarchy. The instances are described by ‘object relations’ which are functions from a set of objects to value sets and other object sets. The rule language is based on object-terms which provide access to objects via the class hierarchy. Rules are divided into two classes: object-preserving rules manipulating existing objects (yielding a new ‘view’ on objects available in the object base) and object-generating rules creating new objects with properties derived from existing objects. The derived object sets are included in a class lattice. We give conditions for whether the instances of the ‘rules’ heads are ‘consistent’, i.e. represent object relations where the properties of the derived objects are functionally determined by the objects.     

A ‘No Panacea Theorem’ for classifier combination

We introduce the ‘No Panacea Theorem’ (NPT) for multiple classifier combination, previously proved only in the case of two classifiers and two classes. In this paper, we extend the NPT to cases of multiple classifiers and multiple classes. We prove that if the combination function is continuous and diverse, there exists a situation in which the combination algorithm will give very bad performance. The proof relies on constructing ‘pathological’ probability density distributions that have high densities in particular areas such that the combination functions give incorrect classification. Thus, there is no optimal combination algorithm that is suitable in all situations. It can be seen from this theorem that the probability density functions (pdfs) play an important role in the performance of combination algorithms, so studying the pdfs becomes the first step of finding a good combination algorithm. Although devised for classifier combination, the NPT is also relevant to all supervised classification problems.     

HCI ‘Intraface Model’ for System Design

We outline an alternative model of the interface in HCI, the ‘intraface’, in response to design issues arising from navigational and learning problems in hypertext domains. Ours is a model of general application to computer systems. It is composed of four key elements, identifiable within a dynamic interconnected context. These are the user; his/her interests; the tools employed and the ‘ensemble’ of representations brought to bear. In this paper we sketch the present shortcomings of HCI design before outlining the background for the model which draws upon two themes in contemporary psychology, conversational analysis and ‘affordance’ realist theories in perception. This framework allows for the development of principles of cooperation, user engagement and learning in HCI environments.     

Detailed design of reinforced concrete buildings using logic programming

A procedure is proposed leading to an optimal detailed design of reinforced concrete members. The general scheme followed is that of a multi-criterion design optimization. The method synthesizes the information from the cross-sectional level, to the member level and finally, to a group of members where the detailed design of the whole group is decided. At the cross-sectional level, the required reinforcement in cm² is converted into reinforcing bars of all possible diameters. At the member and/or group of members level, a number of lists that contain different design scenarios are generated. The method of objective weighting is applied to a multi-criterion objective function, which represents a compromise of the ‘minimum weight’, ‘maximum uniformity’ and ‘minimum number of reinforcing bars’ criteria. By varying the weighting factors, it is possible to generate the Pareto optimal set of the problem. The performance of the system is illustrated with a number of examples. The same building is designed using different weighting factors in the multi-criterion objective. The variation of the detailed designs is discussed and certain values for the weighting factors are recommended.     

An Abstract Böhm-normalization

We study normalization by neededness with respect to ‘infinite results’, such as Böhm-trees, in an abstract framework of Stable Deterministic Residual Structures. We formalize the concept of ‘infinite results’ for finite terms as suitable sets of infinite reductions, and prove an abstract infinitary normalization theorem with respect to such sets. We also give a sufficient and necessary condition for existence of minimal normalizing reductions.     

Canonical constraints for parameterized data types

This paper presents a comparatively general method for specifying a ‘data constraint’ on a parameterized data type (i.e., specifying just which category of algebras it is supposed to be defined or correct on), and shows that there is a simple canonical form for such constraint specifications. We also show how such constraints may be employed to give ‘loose’ specifications of data types.     

Decentralized Output Regulation of a New Class of Interconnected Uncertain Nonlinear Systems

In the current paper the decentralized output regulation problem of a new class of interconnected uncertain nonlinear systems is considered. A novel decentralized high-gain input driven filter is proposed such that the output feedback based control law can be designed. Moreover, a robust multi-input changing supply function technique is presented such that the stability analysis can be performed by the non-quadratic Lyapunov functions. Therefore, the assumptions on the interconnection terms can be removed. Finally the proposed decentralized control laws are applied to the interconnected mass-spring systems immersed in the liquid and the simulation results illustrate the effectiveness of the proposed control scheme.     

Getting to know each other—Artificial social intelligence for autonomous robots

This paper proposes a research direction to study the development of ‘artificial social intelligence’ of autonomous robots which should result in ‘individualized robot societies’. The approach is highly inspired by the ‘social intelligence hypothesis’, derived from the investigation of primate societies, suggesting that primate intelligence originally evolved to solve social problems and was only later extended to problems outside the social domain. We suggest that it might be a general principle in the evolution of intelligence, applicable to both natural and artificial systems. Arguments are presented why the investigation of social intelligence for artifacts is not only an interesting research issue for the study of biological principles, but may be a necessary prerequisite for those scenarios in which autonomous robots are integrated into human societies, interacting and communicating both with humans and with each other. As a starting point to study experimentally the development of robots' ‘social relationships’, the investigation of collection and use of body images by means of imitation is proposed. A specific experimental setup which we use to test the theoretical considerations is described. The paper outlines in what kind of applications and for what kind of robot group structures social intelligence might be advantageous.     

Minimum Projection Method for nonsmooth control Lyapunov function design on general manifolds

Asymptotic stabilization on noncontractible manifolds is known as a difficult control problem. On the other hand, an important fact is every control system that is globally asymptotically stabilizable at a desired equilibrium must have nonsmooth control Lyapunov functions.This paper considers the problem of construction of nonsmooth control Lyapunov functions on general manifolds, and we propose a nonsmooth control Lyapunov function design method called the ‘Minimum Projection Method’. The proposed method considers a simple-structured smooth manifold associated with the original manifold by a surjective immersion, and then a control Lyapunov function defined on the simple-structured manifold is projected to the original manifold. A function on the original manifold is thus obtained.In this paper, we prove that the control system on another manifold associated with a surjective immersion is determined uniquely, and the resulting function by the proposed method is a nonsmooth control Lyapunov function on the original manifold. The effectiveness of the proposed method is confirmed by examples.     

CIPP — a versatile analytical model for VBR traffic

Correlated interarrival time Poisson process (CIPP) has been proposed in Proceedings of the Fifth Biennial Conference on Signal Processing and Communications (SPCOM’99), IISc, Bangalore, July 1999, pp. 43–50; J. Indian Inst. Sci. 79 (3) (1999) 233–249] for modeling both the composite arrival process of packets in broadband networks and the individual video source modeling. The CIPP — a generalization of the Poisson process — is a stationary counting process and is parameterized by correlation parameter ‘ρ’, the degree of correlation in adjacent interarrivals and ‘λ’, the intensity of the process. In this paper, we develop the theory for CIPP/M/1 queue and undertake the performance modeling of statistical multiplexer with VBR video traffic in broadband networks using the CIPP/M/1 queue. We first derive the expressions for stationary distributions for queue length and waiting time in a CIPP/M/1 queue. Then, we derive the queuing performance measures of interest. For reasons of feasibility of theoretical performance modeling and realistic compulsions, we propose a deterministic smoothing with random (geometrically distributed) packet sizes. We simulate a queue with (thus smoothed) VBR video trace data as input to compare with the theoretical performance measures derived above. Experimental results show that the CIPP/M/1 queue models well the statistical multiplexer performance with the real-world MPEG-1 VBR video traffic input.     

Anthropometry of the Hong Kong male and the design of bus driver cabs

This study investigated the proposition that the crabs of buses imported into Hong Kong were not suited to the anthropometric characteristics of the local Chinese bus drivers. A ‘recommended’ cab design was derived from static anthropometric data; relationships between pedals, steering wheel and seat, and the range of seat adjustments were specified. Overall static anthropometric data were available but additional data had to be estimated by constructing manikins based on the available Hong Kong static data with joint positions derived from data for the US male population. Seven bus cab designs in current use were compared with the ‘ recommended’ design. None of them satisfied all the ‘recommended’ design specifications, the most serious deviations being the excessive height of the seat above the floor and pedals, and insufficient lateral separation between the pedals.     

Cheap control problem of a linear uniform rank system: Design by composite control

Cheap control problems where a small parameter μ² multiplies the control cost are considered. Due to the cheapness of control, a strong control action in the form of high-gain feedback forces the given system to have slow and fast, low and high amplitude variations. For a class of linear systems (uniform rank systems), a systematic procedure of amplitude scaling and time-scale decomposition which normalizes high and low amplitude variations and which separates slow and fast time scales is presented. The method permits the explicit characterization of all the limiting properties of the considered cheap control problem as μ → 0. Methods of calculating singular controls and how non-uniqueness can arise in them are discussed. Above all, several suboptimal composite control schemes are developed based on the decomposition of the given optimal design into two lower order subsystem designs.     

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.     

Defining a taxonomy of output modalities from an HCI perspective

The paper addresses an issue that must be resolved to produce a scientifically sound and practically useful reference model for intelligent multimedia presentation systems (IMP systems), namely that of providing, from the point of view of Human-Computer Interaction (HCI), a systematic understanding of the types of output information to be presented by IMP systems. The term ‘medium’, as it is used in the context of multimedia systems, is too coarse-grained for distinguishing between different types of output information. The paper introduces the notion of (representational) ‘modalities’ to enable sufficiently fine-grained distinctions to be made. For the term itself to be meaningful, ‘multimodal’ presentations must be composed of unimodal representations. In the approach presented, unimodal representations are defined from a small number of basic properties whose combinations specify the ‘generic’ level of a taxonomy of unimodal output modalities. Additional basic property distinctions serve to generate the more fine-grained ‘atomic’ and ‘sub-atomic’ levels in a hierarchical fashion. The taxonomy is set up with the aim of satisfying four basic requirements, viz. completeness, orthogonality, relevance and intuitiveness. A concluding discussion illustrates the practical use of the taxonomy.