Tadeusz Dobrowiecki

Tadeusz Dobrowiecki
Budapest University of Technology and Economics · Department of Measurement and Information Systems

Associate Professor

About

60
Publications
4,089
Reads
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1,231
Citations
Additional affiliations
January 1981 - present
Budapest University of Technology and Economics

Publications

Publications (60)
Article
In the overview paper on nonlinear system identification Schoukens and Ljung (2019), it was indicated that reliable expressions to calculate the variance of an estimated nonlinear model are lacking, especially if the disturbing noise is entering the nonlinear regressors. In this study, we provide a better view on the driving mechanisms of the varia...
Conference Paper
We present the architecture of a flexible natural language based interface to robots involved in tasks in a mixed-initiative human-robot environment. The designed interface uses a bidirectional natural language communication pertinent to the user, the robot and the tasks at hand. Tasks are executed via agents that can communicate and engage in conv...
Conference Paper
Full-text available
The interface between humans and computers is an ever critical issue due to the increased complexity of computerized systems and the wide variety of problems they solve. Controlled natural languages might prove a promising medium between humans and computers, however, they are not easy to design, and humans need time to adapt to them. Authors propo...
Article
In many engineering applications, linear models are preferred, even if it is known that the system is nonlinear. A large class of nonlinear systems can be represented as Y = G <sub>BLA</sub> U + YS , with G <sub>BLA</sub> being the best linear approximation and YS being a nonlinear noise source that represents that part of the output that is not ca...
Article
Full-text available
In many engineering applications, linear models are preferred, even if it is known that the system is disturbed by nonlinear distortions. A large class of nonlinear systems, which are excited with a ldquoGaussianrdquo random excitation, can be represented as a linear system G <sub>BLA</sub> plus a nonlinear noise source Y <sub>S</sub> . The nonline...
Article
In many engineering applications, linear models are preferred, even if it is known that the system is nonlinear. A large class of nonlinear systems, excited with random excitations, can be represented as Y = GBLAU + YS, with GBLA the best linear approximation, and YS a nonlinear noise source that represents that part of the output that is not captu...
Conference Paper
Full-text available
Interface agents help users to deal with the complexity of today's computer systems. It is commonly required that these agents should employ natural language to communicate with humans. Natural language processing is, however, a complex and difficult task for agent designers. Authors propose a new framework that significantly reduces the complexity...
Conference Paper
Full-text available
In this paper we present a novel agent-based simulation model for the natural selection of replicating agents whose survival depends on their programs for selecting their strategy to interact with each other. Game theoretic models describe this kind of interaction. The simulator can be used both for analysis, design and verification of autonomous s...
Conference Paper
In this paper we present two new algorithms to solve non-linearly separable classification problems. First we propose a modification of a multiclass support vector machine, which for binary classification tasks can always find a convex polytope that includes the points of one class and excludes the others, if possible. Next we present a generalizat...
Article
The paper addresses the problem of preserving the same LTI approximation of a nonlinear MIMO (multiple-input multiple-output) system. It is shown that when a nonlinear MIMO system is modeled by a multidimensional Volterra series, periodic noise and random multisines are equivalent excitations to the classical Gaussian noise, in a sense that they yi...
Article
Full-text available
The authors present a novel adaptive framework that enables efficient development of applications demanding complex document analysis. In processing natural language documents the task is to transform them into application specific structured form. Such transformation has to be designed taking into account various abstraction levels and granularity...
Article
In this paper it is shown that a nonlinear MIMO system can be replaced by a linear system plus a nonlinear noise source. The optimized measurement strategy is proposed to measure the nonparametric FRF.
Conference Paper
Cascaded nonlinear multiple-input multiple-output (MIMO) systems make it possible to study the influence of a non-ideal generator on the measurements of the nonparametric frequency-response function. The first system in the cascade represents the (non)linear interaction between the generator and the load. The study shows that the measurements of th...
Conference Paper
Full-text available
Autonomous web information systems frequently have to answer queries by extracting information written in non-constrained natural language. This task is modeled as a planning problem. Elementary document processing modules are organized into query dependent information-processing graphs that are the tools of scheduling and controlling the execution...
Conference Paper
Full-text available
Many different measurement setups can be chosen for the nonparametric frequency response function measurements of a linear MIMO system. In the presence of output noise they will result in different SNR of the frequency response function measurements. In the paper, these effects are analyzed and compared for some classes of multisine excitations
Article
This paper studies the impact of nonlinear distortions on linear system identification. It collects a number of previously published methods in a fully integrated approach to measure and model these systems from experimental data. First a theoretical framework is proposed that extends the linear system description to include the impact of nonlinear...
Article
A criterion to verify experimentally the stability of a nonlinear system, captured in a feedback loop, is proposed. The basic idea is to split the output power in coherent (linearly related to the input) and noncoherent power (the remaining power). A nonlinear power gain, measuring the sensitivity of the noncoherent output power to input variations...
Article
In this paper the impact of nonlinear distortions on the linear system identification framework is studied. In the first part the nonlinear system is replaced by a linear model plus a nonlinear noise source. The properties of this representation are studied. Next a method to detect, qualify and quantify the nonlinear distortions is presented. In th...
Conference Paper
We present the goals and the first results of the IKF-H EUREKA project. The main goal of the project is to analyse, design and implement a new intelligent knowledge warehousing environment, allowing for advanced knowledge management and business intelligence, targeted towards specific financial application domain. We describe a general architecture...
Conference Paper
Full-text available
Authors describe a general architecture and a prototype application for the concise storage and presentation of the information retrieved from a wide spectrum of information sources. The proposed architecture was influenced by particular challenges of knowledge intensive domain, mining the knowledge content of primarily unstructured textual informa...
Article
In this paper, we set up a framework to deal with nonlinear distortions in a linear modeling framework. The nonlinear system is replaced by a linear system plus a noise source. The properties of this representation are given and a measurement technique to extract the linear model and the noise variance is developed. Eventually, the different aspect...
Article
The increasing amount and variety of domain knowledge and the availability of increasingly large quantities of electronic literature requires new types of support for the development of complex knowledge models. In previous publications we proposed the application of so called Annotated Bayesian Networks (ABN), textually enriched probabilistic doma...
Conference Paper
The increasing amount and variety of domain knowledge and the availability of increasingly large quantities of electronic literature requires new types of support for the development of complex knowledge models. P. Antal et al. (2001) proposed the application of so-called annotated Bayesian networks (ABNs), which are textually-enriched probabilisti...
Article
In this paper authors present a system for information and knowledge fusion that provides an integrated management of information in a particular task domain. The proposed system uses structured (database and XML-based) and unstructured (information retrieval) data acquisition techniques, various knowledge representation schemes to integrate retrie...
Article
Full-text available
: In the paper we present a design of a decision support system for the fully automated controlled retrieval of fiscal information, which is being continuously collected from a variety of sources, mainly from the global computer network. This system extends the idea of data mining to the notion of knowledge retrieval. The collected information is p...
Article
Multisine excitation signals are designed which will be used to detect and qualify the nonlinear distortions on frequency response function (FRF) measurements, and this without making additional experiments. The main idea in this method is to apply well chosen periodic excitations where not all harmonics are excited. The nonexcited frequency lines...
Conference Paper
Full-text available
In this paper authors present a system for information and knowledge fusion that provides an integrated management of information in a particular task domain. The proposed system uses structured (database and XML-based) and unstructured (information retrieval) data acquisition techniques, various knowledge representation schemes to integrate retrie...
Article
In this paper, we deal with the measurement of the frequency response function (FRF) of linear dynamic systems in the presence of nonlinear distortions. It is shown that it is possible to detect, qualify and quantify the nonlinear distortions during a broadband frequency response measurement. Advises are formulated how to get the best measurements...
Conference Paper
In this paper we present a procedure to generate nonparametric bounds on the model errors of a measured frequency response function that are due to nonlinear distortions. In a first step the nonlinear system is represented by a linear system (the best linear approximation) plus a noise source that accounts for the unmodelled nonlinear effects. In a...
Conference Paper
In this paper we set up a framework to deal with nonlinear distortions in a linear modelling framework. The nonlinear system is replaced by a linear system plus a noise source. The properties of this representation are given, and a measurement technique to extract the linear model and the noise variance is developed. Eventually the different aspect...
Article
The frequency Responce Function (FRF) of the best linear approximation to a nonlinear system is usually measured by averaging system responces to a normally distributed, filtered and clipped random excitation (Gaussian noise). This signal is compared to the multisine signal with random phases. It is shown that a random phase multisine signal define...
Conference Paper
Full-text available
Artificial intelligence planning methods haven't been used until rec ently to address the problem of computer-aided process planning (CAPP) in manufacturing in its entirety. They were simply not developed enough to tackle real-world problems of that complexity. In the paper we show that with so-called Hierarchical Task Networks, a recently matured...
Conference Paper
Full-text available
We have previously (2000) reported on the development of Bayesian network models for the pre-operative discrimination between malignant and benign ovarian masses. The models incorporated both medical background knowledge and patient data, which required the traceability of the incorporated prior medical knowledge. For this purpose, we followed a pa...
Article
In this paper we deal with the measurement of the frequency response function (FRF) of linear dynamic systems in the presence of nonlinear distortions. It is shown that it is possible to detect, qualify and quantify the nonlinear distortions during a broadband frequency response measurement. Advises are formulated how to get the best measurements u...
Article
The paper presents a review of so called agent systems. Agent is a new paradigm of an intelligent system embedded in the environment of the global computer network. Considering that the fusion of the measurement and the global computer networks became already a reality and that measurement is a knowledge intensive, systems which can realize complic...
Article
Full-text available
It is widely accepted that the introduction of emotions means necessarily an upgrading of the cognitive abilities of an agent system [2, 10, 11, 16]. Although everybody is aware that there is an essential gap between the artificial nature of an agent system and the human character of implemented emotions, this problem lacked a closer look, and some...
Conference Paper
This paper presents a method to design broadband excitation signals with a user imposed power spectrum and amplitude distribution. If necessary, the crest factor can also be reduced by setting a don't care region at the tails of the desired amplitude density function
Article
Authors investigate how distributed artificial intelligence (DAI) techniques can contribute to the today's complex and distributed measuring systems. The blackboard architecture suits well to the measurement design, where several aspects of the same problem should be considered simultaneously. On the other hand, intelligent agents can help to explo...
Article
to put together signal processing schemes [14]. AI entered the picture when the increasing complexity of problems brought into focus qualitative aspects of measurable objects. Knowledge representation, symbolic signal processing, nonanalytic means of modeling measurement uncertainty, and many other issues received deserved attention and, in certain...
Article
This paper studies the asymptotic behavior of nonparametric and parametric frequency domain identification methods to model linear dynamic systems in the presence of nonlinear distortions under some general conditions for random multisine excitations. In the first part, a related linear dynamic system (RLDS) approximation to the nonlinear system (N...
Article
Introduction With the spread of computers and the revolutionary development of network facilities highly distributed systems evolved. Such systems make it possible to reconsider the idea of fault tolerance at a higher level of abstraction. Distributed architecture leads directly to distributed diagnosis, and generally speaking, it has much more pot...
Article
this article a new modelling method is proposed with the following important potential advantages, which distinguish it from previous solutions for achieving fault tolerance:
Conference Paper
For pt. I see ibid., p. 1216-21 (1995). This paper concerns the asymptotic behaviour of parametric frequency-domain identification methods to model linear dynamic systems in the presence of nonlinear distortions, using random multisine excitations. Consistency is shown with respect to the general conditions. A function of dependency is defined to d...
Conference Paper
This paper concerns the asymptotic behaviour of nonparametric frequency-domain identification methods to model linear dynamic systems in the presence of nonlinear distortions, using random multisine excitations. The nonparametric behavior of the transfer function measurement is studied. A related dynamic system (RLDS) is defined and linked to the c...
Conference Paper
Traditional solutions for achieving fault-tolerance are intended for use at design time and they generally capture system information at a very low (hardware or machine instruction) level. Increasing reliability of complex information systems containing many (perhaps many thousands) of autonomous components requires different solutions. This articl...
Conference Paper
The analytic approach to signal processing performs well if there is adequate understanding of the characteristics of the signal source. In more complicated cases, syntactic signal-processing tools used to be a working alternative; however, these share the common algorithmic background with the numerical methods. On the other hand, the filed area o...
Conference Paper
The authors have developed a real-time signal analyzer, which, by monitoring EEG signals, can provide the optimal control of the parameters of the EEG recorder. The signal processing scheme and the implementation issues of the analyzer are described, with emphasis on the knowledge-based subsystem. The first phase of the signal processing is a featu...
Article
Real-time monitoring systems are to provide information within a limited response time about the operation of a time variant system that has a complex model. For the sake of preventing the information overload in the operators' room a need for selective, feature extracted information displaying, monitoring, alarming system has arised, A straightfor...
Article
Full-text available
Autonomous information systems, which answer complex queries by extracting information from electronic sources written in natural language, must be designed for maximum flexibility and adaptivity. This paper proposes an approach that is based upon the library of elementary document processing modules organized adaptively from query to query into an...
Article
Full-text available
Various document parsing methods are required in applications that per-form complex information extraction. The development of such parsing schemes can be simplified by decomposing the complex extraction process into simple steps that can be realized by elementary parser modules. Authors present a general framework for the development of IE applica...
Article
In this paper we deal with the measurement of the frequency response function (FRF) of linear dynamic systems in the presence of non-linear distortions. The aim of this paper is to provide the reader insight in the impact of non-linear distortions on FRF measurements. It is shown how to measure the best linear approximation; how to detect, qualify...

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