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Found 5152 publications

3D model estimation from multiple images

András Rövid P. Várlaki A. 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

Characterization of the temporal pattern of cerebral blood flow oscillations

Gábor Lenzsér Balázs Benyó B. Paláncz

Publication Name: IEEE International Conference on Neural Networks Conference Proceedings

Publication Date: 2004-12-01

Volume: 3

Issue: Unknown

Page Range: 2467-2470

Description:

Oscillation of the cerebral blood flow (CBF) is a common feature in several physiological or pathophysiological states of the brain. It is a promising opportunity to identify the state of the brain based on the classification of CBF signals. In order to carry out classification of the time signals, a feature vector has been extracted to characterize the signals. Unsupervised classification showed that the extracted feature vector is an acceptable representation of the time signals. It also turned out that the difference between normal signal and a signal indicating drug injection effect is significant, and much more dominant than the difference between signals of the right and left brain sides. For the signal classification an Artificial Neural Network (ANN) model based on supervised backpropagation network has been developed and successfully applied.

Open Access: Yes

DOI: 10.1109/IJCNN.2004.1381016

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

Tamás Dusek

Publication Name: Cybergeo

Publication Date: 2004-12-01

Volume: 2004

Issue: Unknown

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: Yes

DOI: DOI not available

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

Slewing of rubber-sprung wheels with railway vechiles

László Kiss Laszlo Bozoky 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

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

Design of B-spline neural networks using a bacterial programming approach

C. Cabrita J. Botzheim A. E. Ruano L. T. Koczy

Publication Name: IEEE International Conference on Neural Networks Conference Proceedings

Publication Date: 2004-12-01

Volume: 3

Issue: Unknown

Page Range: 2313-2318

Description:

The design phase of B-spline neural networks represents a very high computational task. For this purpose, heuristics have been developed, but have been shown to be dependent on the initial conditions employed. In this paper a new technique, Bacterial Programming, is proposed, whose principles are based on the replication of the microbial evolution phenomenon. The performance of this approach is illustrated and compared with existing alternatives.

Open Access: Yes

DOI: 10.1109/IJCNN.2004.1380987

Geometric construction of carbon nanotube junctions

I. Zsoldos T. Reti A. Szasz Gy Kakuk

Publication Name: Modelling and Simulation in Materials Science and Engineering

Publication Date: 2004-11-01

Volume: 12

Issue: 6

Page Range: 1251-1266

Description:

In this work we demonstrate that carbon nanotube junctions with an optional number, type (zigzag and/or armchair) and diameter of tubes can exist. We show a method for geometric construction of their models.

Open Access: Yes

DOI: 10.1088/0965-0393/12/6/017

Boundary interpolation vs boundary elements: Theory and some applications

Csaba Gáspár

Publication Name: International Series on Advances in Boundary Elements

Publication Date: 2004-10-11

Volume: 19

Issue: Unknown

Page Range: 143-152

Description:

Domain and boundary type meshless methods based on the Direct Multi-Elliptic Interpolation Method are presented. The approach is equivalent to a special RBF-method but completely avoids the solution of large, full and ill-conditioned systems, thus, the computational cost is significantly reduced. The method is illustrated through the example of the usual Poisson problem. Both Dirichlet and Neumann boundary conditions are investigated. The domain version of the method results in particular solutions, while the boundary version can be applied to solve homogeneous problems. Along Neumann boundaries, either off-boundary points can be introduced or a boundary reconstruction technique based on boundary interpolation can be applied. Some further possible applications are also outlined.

Open Access: Yes

DOI: DOI not available