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Found 6515 publications

Spatially aggregated data and variables in empirical analysis and model building for economics

No authors available

Publication Name: CyberGeo

Publication Date: 2004-12-01

Volume: 2004

Issue:

Page Range: Unknown

Description:

A short review of the importance of spatial aggregation problem in general and specially in economics is followed by a typology of spatial analysis and statistical data from spatial aggregation viewpoint. The modifiable areal unit problem is divided into two parts. There are the scale and the zoning system effects, which are illustrated using Hungarian data. Spatial data aggregation creates the need for investigating the connection between the theory and data as well as the micro-macro dualism.

Open Access: No

DOI: DOI not available

Estimating fuzzy membership functions parameters by the levenberg-marquardt algorithm

János Botzheim Cristiano L. Cabrita António E. Ruano Laszlo T. Koczy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2004-12-01

Volume: 3

Issue: Unknown

Page Range: 1667-1672

Description:

In previous papers from the authors fuzzy model identification methods were discussed. The bacterial algorithm for extracting fuzzy rule base from a training set was presented. The Levenberg-Marquardt algorithm was also proposed for determining membership functions in fuzzy systems. In this paper the Levenberg-Marquardt technique is improved to optimise the membership functions in the fuzzy rules without Ruspini-partition. The class of membership functions investigated is the trapezoidal one as it is general enough and widely used. The method can be easily extended to arbitrary piecewise linear functions as well.

Open Access: Yes

DOI: 10.1109/FUZZY.2004.1375431

Logic testing of CMOS structures

Jozsef Sziray

Publication Name: Iccc 2004 Second IEEE International Conference on Computational Cybernetics Proceedings

Publication Date: 2004-12-01

Volume: Unknown

Issue: Unknown

Page Range: 59-64

Description:

The paper presents a test calculation principle which serves for producing tests of switch-level logic faults in CMOS digital circuits. The considered fault model includes stuck-at-0/1 logic faults on the connecting lines, as well as switch faults in the transistors. Both single and multiple faults are included. The transistor faults manifest themselves in stuck open (open circuit) and stuck short (short circuit) behavior. In this paper only combinational logic circuits are taken into consideration. The calculation principle is comparatively simple. It is based only on successive line-value justification, and it yields an opportunity to be realized by an efficient computer program. ©2004 IEEE.

Open Access: Yes

DOI: DOI not available

Construction of fuzzy signature from data: An example of S ARS pre-clinical diagnosis system

Tamás D. Gedeon Laszlo T. Koczy Kok Wai Wong

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2004-12-01

Volume: 3

Issue: Unknown

Page Range: 1649-1654

Description:

There are many areas where objects with very complex and sometimes interdependent features are to be classified; similarities and dissimilarities are to be evaluated. This makes a complex decision model difficult to construct effectively. Fuzzy signatures are introduced to handle complex structured data and interdependent feature problems. Fuzzy signatures can also used in cases where data is missing. This paper presents the concept of a fuzzy signature and how its flexibility can be used to quickly construct a medical pre-clinical diagnosis system. A Severe Acute Respiratory Syndrome (SARS) pre-clinical diagnosis system using fuzzy signatures is constructed as an example to show many advantages of the fuzzy signature. With the use of this fuzzy signature structure, complex decision models in the medical field should be able to be constructed more effectively.

Open Access: Yes

DOI: 10.1109/FUZZY.2004.1375428

3D model estimation from multiple images

András Rövid Péter Várlaki Annamária R. Várkonyi-Kóczy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2004-12-01

Volume: 3

Issue: Unknown

Page Range: 1661-1666

Description:

3D reconstruction plays a very important role in computer vision. The determination of the 3D model from multiple images is of key importance. In this paper a 3D reconstruction algorithm is introduced, which is capable to determine the 3D model without any external intervention.

Open Access: Yes

DOI: 10.1109/FUZZY.2004.1375430

Application of interpolation-based fuzzy logic reasoning in behaviour-based control structures

Szilveszter Kovacs Laszlo T. Koczy

Publication Name: IEEE International Conference on Fuzzy Systems

Publication Date: 2004-12-01

Volume: 3

Issue: Unknown

Page Range: 1543-1548

Description:

Some difficulties emerging during the construction of fuzzy behaviour-based control structures are inherited from the type of the applied fuzzy reasoning. The fuzzy rule base requested for many classical reasoning methods needed to be complete. In case of fetching fuzzy rules directly from expert knowledge e.g. for the behaviour coordination module, the way of building a complete rule base is not always straightforward. One simple solution for overcoming the necessity of the complete rule base is the application of interpolation-based fuzzy reasoning methods, since interpolation-based fuzzy reasoning methods can serve usable (interpolated) conclusion even if none of the existing rules is hit by the observation. These methods can save the expert from dealing with derivable rules and help to concentrate on cardinal actions only. For demonstrating the applicability of the interpolation-based fuzzy reasoning methods in behaviour-based control structures a simple interpolation-based fuzzy reasoning method and its adaptation for behaviour-based control will be introduced briefly in this paper.

Open Access: Yes

DOI: 10.1109/FUZZY.2004.1375404

Filtering and contrast enhancement on subtracted direct digital angiograms

Balázs Benyó L. Nagy

Publication Name: Annual International Conference of the IEEE Engineering in Medicine and Biology Proceedings

Publication Date: 2004-12-01

Volume: 26 II

Issue: Unknown

Page Range: 1533-1536

Description:

This paper presents the results of a research related to medical image subtraction algorithms. The selected area is of direct digital X-Ray angiography, where subtraction algorithms are the basis of most acquisition and reviewing protocols. The goal of this research is to analyze the currently existing image subtraction algorithms and to propose a new approach based on the experienced limitations, respectively to develop a new imaging technique that allows both contrast agent and radiation dose reduction. The enhancement of the subtraction algorithms is targeted by two means: a) noise reduction on image frames, b) identification of contrast agent injected regions. Both aspects will be studied based on the analysis of the spatio-temporal signal variation that image pixel intensities represent, therefore the resulting algorithm can not be used real time during image acquisition, but as a post processing technique during review. The temporal variation of pixel intensities was then analyzed and a patter check was followed to identify pixels being part of a contrast agent injected region. This information was used to highlight regions of interest and to increase the contrast in poorly injected areas.

Open Access: Yes

DOI: DOI not available

On the positivity of matrix-vector products

Zoltán Horváth

Publication Name: Linear Algebra and Its Applications

Publication Date: 2004-12-01

Volume: 393

Issue: 1-3

Page Range: 253-258

Description:

In this paper we examine the positivity of Rv where R∈R N×N, v∈RN, v≥0 with R=r(τA), r is a given (rational) function, A∈RN×N and τ∈(0,∞). Here we mean by positivity the ordering w.r.t. an arbitrary order cone, which includes the classical entrywise positivity of vectors. Since the requirement R≥0 leads to very severe restrictions on r and τ we construct a positive cone ℘=℘(A) and determine τ*=τ*(r,℘) such that r(τA)℘⊂℘ for all τ∈[0,τ*]. Finally we give an example arising from applications to partial differential equations where our results explain actual computations much better than the general theory on R≥0. © 2004 Elsevier Inc. All rights reserved.

Open Access: Yes

DOI: 10.1016/j.laa.2004.03.012

Slewing of rubber-sprung wheels with railway vechiles

László Kiss László Bozóky Vince Nagy

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics Identification and Anomalies

Publication Date: 2004-12-01

Volume: Unknown

Issue: Unknown

Page Range: 171-175

Description:

The slewing of railway vehicle's rubber-spring wheel means that the wheel has an elastic and plastic change in angle relative to the wheel frame. This study has the objective to explore the evolution and the causes for these angle changes both in laboratory environment and also during the running of the vehicle.

Open Access: Yes

DOI: DOI not available