Ano (172)
Použitá omezení
(2)
Počet nalezených dokumentů:
172
Publikováno od
do
A New Concept of PTP Vector Network Analyzer
Závodný, Vadim; Hoffmann, Karel; Škvor, Zbyněk
2004 -
A new concept for vector network analyzers design based on a perturbation two-port (PTP) is presented. The approach uses redundant states of the PTP. The best states of the PTP for a certain place in Smith chart and frequency are chosen to determine a reflection coefficient with minimum uncertainty. Four criteria for the selection are designed. The criteria were tested on measured parameters of different states of the PTP. Significant improvements in PTP bandwidth and uncertainty of measured data were achieved.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
A New Concept of PTP Vector Network Analyzer
A new concept for vector network analyzers design based on a perturbation two-port (PTP) is presented. The approach uses redundant states of the PTP. The best states of the PTP for a certain place in ...
High-Dimensional Mutual Information Estimation For Image Registration
Kybic, Jan
2004 -
We present a new algorithm for mutual information estimation for image registration based on the nearest neighbor entropy estimator of Kozachenko and Leonenko. We modify the algorithm to be numerically robust and computationally efficient, with optimal asymptotic complexity O(Npixelsddim). We propose two MI-based criteria exploiting the high-dimensionality of the feature space and show their effectiveness in determining the correct alignment even in difficult cases when classical criteria fail.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
High-Dimensional Mutual Information Estimation For Image Registration
We present a new algorithm for mutual information estimation for image registration based on the nearest neighbor entropy estimator of Kozachenko and Leonenko. We modify the algorithm to be ...
Radial Radon Transform dedicated to Micro-object Localization from Radio Frequency Ultrasound Signal
Barva, Martin; Kybic, Jan; Mari, Jean-Martial; Cachard, Christian
2004 -
In this paper we describe a method for automatic electrode localization in soft tissue from a radiofrequency signal. The method exploits a property of the Radon transform (RT) that allows us to localize a line-segment in 3D data. The method directly processes the radiofrequency (RF) signal provided by the ultrasound (US) probe. Thus, there is no need for ultrasound image reconstruction. The method is able to detect line-segments that are discontinuous. The low computational cost allows us to process data in real-time. The algorithm was tested on a radiofrequency signal acquired by scanning a phantom containing a thin metal electrode of 150 μm in diameter. The experiments show that the developed technique is capable of reliably finding an arbitrarily positioned line-segment in a 3D image.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Radial Radon Transform dedicated to Micro-object Localization from Radio Frequency Ultrasound Signal
In this paper we describe a method for automatic electrode localization in soft tissue from a radiofrequency signal. The method exploits a property of the Radon transform (RT) that allows us to ...
Inter-stage Feature Propagation in Cascade Building with AdaBoost
Šochman, Jan; Matas, Jiří
2004 -
A modification of the cascaded detector with the Ada-Boost trained stage classifiers is proposed and brought to bear on the face detection problem. The cascaded detector is a sequential classifier with the ability of early rejection of easy samples. Each decision in the sequence is made by a separately trained classifier, a stage classifier. In proposed modification the features from one stage of training are propagated to the next stage classifier. The proposed intra-stage feature propagation is shown to be greedily optimal, does not increase computational complexity of the stage classifier and leads to shorter stage classifiers and accordingly to faster detectors. A cascaded face detector is built with the intra-stage feature propagation and is compared with the Viola and Jones approach. The same detection and false positive rates are achieved with a detector that is 25% faster and consists of only two thirds of the weak classifiers needed for a cascade trained by the Viola and Jones approach. The latter property facilitates hardware implementation, the former opens scope for the increase in the search space, e.g., the range of scales at which faces are sought.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Inter-stage Feature Propagation in Cascade Building with AdaBoost
A modification of the cascaded detector with the Ada-Boost trained stage classifiers is proposed and brought to bear on the face detection problem. The cascaded detector is a sequential classifier ...
Epipolar Geometry Estimation via RANSAC Benefits from the Oriented Epipolar Constraint
Chum, Ondřej; Werner, Tomáš; Matas, Jiří
2004 -
The efficiency of epipolar geometry estimation by RANSAC is improved by exploiting the oriented epipolar constraint. Performance evaluation shows that the enhancement brings up to a two-fold speed-up. The orientation test is simple to implement, is universally applicable and takes negligible fraction of time compared with epipolar geometry computation.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Epipolar Geometry Estimation via RANSAC Benefits from the Oriented Epipolar Constraint
The efficiency of epipolar geometry estimation by RANSAC is improved by exploiting the oriented epipolar constraint. Performance evaluation shows that the enhancement brings up to a two-fold speed-up. ...
Dispersion Characteristics of the Dominant Mode on a Completely Shielded Conductor-Backed Slotline
Zehentner, Ján; Macháč, Jan; Mrkvica, Jan
2004 -
This paper presents an analysis of a completely shielded conductor-backed slotline using the spectral domain technique. Attention is paid to dominant and higher order modes with even symmetry of the transversal electric field component in the slot parallel to the dielectric interface. The dependence of the phase constant and the characteristic impedance of the line on cross-sectional size, permittivities and frequency are given. It has turned out that the line is suitable for circuit design when the dominant requirement is for low characteristic impedance. Numerical examples highlight particular aspects of the mode propagation over the line. The consequence of setting ε0 in the whole cross-section of the line is a waveguide containing a partition in the H plane with a longitudinal slot. An analysis of this guide by the spectral domain method is presented and typical frequency dependent phase constant and characteristic impedance patterns are shown.
Klíčová slova:
dominant mode; planar transmission line; shielded conductor-backed slotline; waveguide slotted partition
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Dispersion Characteristics of the Dominant Mode on a Completely Shielded Conductor-Backed Slotline
This paper presents an analysis of a completely shielded conductor-backed slotline using the spectral domain technique. Attention is paid to dominant and higher order modes with even symmetry of the ...
AdaBoost with Totally Corrective Updates for Fast Face Detection
Šochman, Jan; Matas, Jiří
2004 -
An extension of the AdaBoost learning algorithm is proposed and brought to bear on the face detection problem. In each weak classifier selection cycle, the novel totally corrective algorithm reduces aggressively the upper bound on the training error by correcting coefficients of all weak classifiers. The correction steps are proven to lower the upper bound on the error without increasing computational complexity of the resulting detector. We show experimentally that for the face detection problem, where large training sets are available, the technique does not overfit. A cascaded face detector of the Viola-Jones type is built using AdaBoost with the totally corrective update. The same detection and false positive rates are achieved with a detector that is 20% faster and consists of only a quarter of the weak classifiers needed for a classifier trained by standard AdaBoost. The latter property facilitates hardware implementation, the former opens scope for the increease in the search space, e.g the range of scales at which faces are sought.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
AdaBoost with Totally Corrective Updates for Fast Face Detection
An extension of the AdaBoost learning algorithm is proposed and brought to bear on the face detection problem. In each weak classifier selection cycle, the novel totally corrective algorithm reduces ...
Testing of Normality of Data Files for Application of SPC Tools
Mach, Pavel; Hochlová, Hana
2004 -
Different types of statistical tests have been used for evaluation of the normality of selected data files. The files have been simulated to be on the border of normality. The results of the tests have been compared. It has been found that some files have been, using some type of a test, marked as normal, but using another type of a test, marked as non-normal. It is possible to find similar results by normality testing of data files obtained from production. Therefore, complementary tools for assessment of normality of the files under test have to be used. This paper compares results of normality testing of some simulated files by three basic tests of normality: test of elective skewness and kurtosis, Anderson-Darling test, and Kolmogorov-Smirnov test. It gives also directions indicating which other tools of exploratory analysis have to be used for verification of results obtained by different tests of normality.
Klíčová slova:
normality test; test of elective skewness and kurtosis; Anderson-Darling test; Kolmogorov-Smirnov test; exploratory analysis; SPC
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Testing of Normality of Data Files for Application of SPC Tools
Different types of statistical tests have been used for evaluation of the normality of selected data files. The files have been simulated to be on the border of normality. The results of the tests ...
Visualization of leaky waves on planar transmission lines
Macháč, Jan; Zehentner, Ján; Mrkvica, Jan
2004 -
This paper presents a visualization of leaky waves excited by delta-gap sources on planar transmission lines, namely the 2nd surface and space leaky modes on the slotline, and the dominant and surface leaky modes on the conductor-backed slotline. The field is modeled by numerical calculation in the time domain. The simulations show the character of the leaky waves excited by delta-gap sources and are a useful tool for the investigation of leaky waves.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Visualization of leaky waves on planar transmission lines
This paper presents a visualization of leaky waves excited by delta-gap sources on planar transmission lines, namely the 2nd surface and space leaky modes on the slotline, and the dominant and surface ...
Influence of trimming of resistive thick films on nonlinearity of their current vs. voltage characteristics
Mach, Pavel; Svasta, Pavel
2004 -
Investigation of changes of nonlinearity of thick resistive films, trimmed by laser and by grinding, has been carried out. Laser trimming has been realized by an Ar laser, mechanical trimming by grinding of the layer by a milling machine using a diamond miller. The simplest method of trimming has been used - the resistors have been trimmed by realization of a groove, approximately in the middle of their length, perpendicularly to the axes of the resistors. The length of the trimming groove has been from 10% to 80% of the width of the resistor. All measured values of nonlinearity after trimming have been recalculated for starting values of the resistors. Nonlinearity has been examined for constant current density at the narrowest cross section of the resistive layer. It has been found that changes of nonlinearity caused by trimming depend on the ratio of the width and the length of the resistors. The changes have been very similar for resistors trimmed by the laser and for resistors trimmed mechanically.
Klíčová slova:
thick film resistors; nonlinearity of I-V characteristic; laser trimming; mechanical trimming
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Influence of trimming of resistive thick films on nonlinearity of their current vs. voltage characteristics
Investigation of changes of nonlinearity of thick resistive films, trimmed by laser and by grinding, has been carried out. Laser trimming has been realized by an Ar laser, mechanical trimming by ...
NUŠL poskytuje centrální přístup k informacím o šedé literatuře vznikající v ČR v oblastech vědy, výzkumu a vzdělávání. Více informací o šedé literatuře a NUŠL najdete na webu služby.
Vaše náměty a připomínky posílejte na email nusl@techlib.cz
Provozovatel
Zahraniční báze