Ano (172)
Použitá omezení
(2)
Počet nalezených dokumentů:
172
Publikováno od
do
Transformation of Data for Statistical Processing
Mach, Pavel; Thuring, Josef; Šámal, David
2006 -
The use of many statistical tools depends on normality of processed data. There are different methods for transformation of non-normally distributed data sets toward to normally distributed ones. The goal of the work has been to investigate usability of four types of transformations (Box-Cox, exponential, power and logarithmic) for transformation of data sets with four non-normal distributions (logarithmic-normal, exponential, gamma, and Weibull) toward to normally distributed data. The usability and efficiency of individual transformation functions for transformation of data sets with different types of distributions have been found.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Transformation of Data for Statistical Processing
The use of many statistical tools depends on normality of processed data. There are different methods for transformation of non-normally distributed data sets toward to normally distributed ones. The ...
Modeling of Evaporation of Thin Films Using DOE
Mach, Pavel; Kocián, Miroslav
2006 -
Evaporation of thin films is widely spread technology. The goal of the work has been to optimize a process of fabrication of thin resistive Ni films. Mathematical models for calculation of thickness and resistance of the films have been created. A method of design of experiments has been used for design of the models. Three types of models have been designed and tested: a linear model, a combined one and a short combined one. First the models have been verified using an F-test. It has been found that a linear model is not satisfactory, therefore it has been rejected. Subsequently remaining two models have been verified by complementary experiments, when calculated values and values measured on newly fabricated films have been compared. It has been found an excellent conformity among calculated and measured values (plusmn 3%). Then the optimum fabrication conditions have been found by optimization of the models.
Klíčová slova:
evaporation; thin film; DOE; statistical testing
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Modeling of Evaporation of Thin Films Using DOE
Evaporation of thin films is widely spread technology. The goal of the work has been to optimize a process of fabrication of thin resistive Ni films. Mathematical models for calculation of thickness ...
Diagnostic Tools for Evaluation of the Quality of the Anisotropic Conductive Adhesive Joints
Duraj, Aleš; Mach, Pavel
2006 -
Isotropic and anisotropic electrically conductive adhesives (ICAs and AC As) are materials for special applications in electronic assembly. Quality of these adhesive joints is evaluated according of their electrical and mechanical properties. This paper is focused on evaluation of quality of Anisotropic Conductive Adhesives. Especially dependence of electrical resistance, noise and nonlinearity on bonding pressure is the main purpose of this research. Effect of curing (bonding) pressure ofACA was also analyzed with scanning electron microscope (SEM). Also influence of three different types of surface finishes (Cu, Cu+Sn, Cu+Ni/Au) of printed circuit boards has been examined and then evaluated effects on measured parameters.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Diagnostic Tools for Evaluation of the Quality of the Anisotropic Conductive Adhesive Joints
Isotropic and anisotropic electrically conductive adhesives (ICAs and AC As) are materials for special applications in electronic assembly. Quality of these adhesive joints is evaluated according of ...
Equipment for measurement of nonlinearity of nominally linear components
Mach, Pavel; Papež, Václav; Bušek, David; Duraj, Aleš
2006 -
Nonlinearity of a nominally linear component is a significant parameter, which informs about the difference of and investigated component from an ideal one. The higher is quality of the nominally linear component; the lower is level of its nonlinearity. Nonlinearity is caused by inhomogenities and unstable barriers in the component, which can, after some time, cause failure of the component. Nonlinearity is also a significant technical parameter of components, which work with more signals of different levels. Nonlinearity contributes here to generation of intermodulation distortion of current signals. It has been necessary, for our research, to investigate nonlinearity of adhesive joints. Because there is not equipment for measurement of nonlinearity of low-impedance components on the market, it has been necessary to construct it. Equipment is based on evaluation of intermodulation distortion, which is generated by the nonlinear component, when two sinusoidal signals are fed into it. Equipment makes a measurement of nonlinearity of 2. to 5. order possible. Measured level of nonlinearity is -170 dB with respect to the actuating signal. Maximum power of the actuating signal is 2 VA, the sensitivity of an indicator 50 nV. Some examples of measurements of nonlinearity of adhesive joints are shown.
Klíčová slova:
evaporation; thin film; DOE; statistical testing
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Equipment for measurement of nonlinearity of nominally linear components
Nonlinearity of a nominally linear component is a significant parameter, which informs about the difference of and investigated component from an ideal one. The higher is quality of the nominally ...
Reflection from a Gold Sputtered Thin Layer
Buchar, Pavel; Macháč, Jan; Zehentner, Ján; Slepička, Petr; Švorčík, Václav
2006 -
This paper presents the results of an investigation of a thin layer of gold sputtered on a dielectric foil. This layer is modeled by nanometer-scale spherical particles that are separated at short deposition times and later touch each other, forming a continuous layer. Four ways of analyzing the structure are introduced. The first method describes the spheres by their electric dipole moment, while the second, newly proposed method, takes into account the capacity between adjacent spheres, and the third method assumes the layer as homogeneous and considers its reduced conductivity due to the behavior of electrons in thin films. The CST microwave studio model, which takes into account the random distribution of particles, offers the reflection coefficient that best fits measured data.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Reflection from a Gold Sputtered Thin Layer
This paper presents the results of an investigation of a thin layer of gold sputtered on a dielectric foil. This layer is modeled by nanometer-scale spherical particles that are separated at short ...
Epipolar Geometry from Two Correspondences
Perd’och, Michal; Matas, Jiří; Chum, Ondřej
2006 -
A novel algorithm for robust RANSAC-like estimation of epipolar geometry (of uncalibrated camera pair) from two correspondences of local affine frames (LAFs) is presented. Each LAF is constructed from three points independently detected on a maximally stable extremal region. The algorithm assumes that a sufficiently accurate approximation of the fundamental matrix is obtained from two LAF correspondences by the 6-point algorithm of Stewenius et al. The so-far-the-best hypotheses are further processed by so-called local optimization to estimate the epipolar geometry. Special attention is paid to planar sample degeneracy, since the probability of drawing two coplanar LAF correspondences is not negligible. Combining the 6-point solver, local optimization, and the degeneracy test enables RANSAC to draw samples of only two LAFs to generate hypotheses and thus to reduce the number of samples drawn. We experimentally show that using the 6-point algorithm (approximating the real camera by camera with unit aspect ratio, zero skew, principal point in the center of image, and a common unknown focal length) generates hypotheses that are sufficient for EG estimation in LO-RANSAC framework.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Epipolar Geometry from Two Correspondences
A novel algorithm for robust RANSAC-like estimation of epipolar geometry (of uncalibrated camera pair) from two correspondences of local affine frames (LAFs) is presented. Each LAF is constructed from ...
Randomized RANSAC with Sequential Probability Ratio Test
Matas, Jiří; Chum, Ondřej
2005 -
A randomized model verification strategy for RANSAC is presented. The proposed method finds, like RANSAC, a solution that is optimal with user-controllable probability n. A provably optimal model verification strategy is designed for the situation when the contamination of data by outliers is known, i.e. the algorithm is the fastest possible (on average) of all randomized RANSAC algorithms guaranteeing 1 - n confidence in the solution. The derivation of the optimality property is based on Wald's theory of sequential decision making. The R-RANSAC with SPRT which does not require the a priori knowledge of the fraction of outliers and has results close to the optimal strategy is introduced. We show experimentally that on standard test data the method is 2 to 10 times faster than the standard RANSAC and up to 4 times faster than previously published methods.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Randomized RANSAC with Sequential Probability Ratio Test
A randomized model verification strategy for RANSAC is presented. The proposed method finds, like RANSAC, a solution that is optimal with user-controllable probability n. A provably optimal model ...
Coplanar Waveguide Transmitting a Left-Handed Wave
Macháč, Jan; Hudlička, Martin; Zehentner, Ján; Spiliotis, Nikolaos G.; Omar, Abbas S.
2005 -
This paper presents a new version of a coplanar waveguide that transmits a left-handed wave. The equivalent circuit of the line unit cell has been derived from the shape of the layout. The values of its elements were determined by fitting the dispersion characteristic of the equivalent circuit to the dispersion characteristic of the first left-handed mode of the line calculated by the CST Microwave Studio. This dispersion characteristic was checked by an experiment. The measured frequency dependences of S11 and S21 fit well the data predicted by simulation. The line is uniplanar and does not contain any lumped elements or vias.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Coplanar Waveguide Transmitting a Left-Handed Wave
This paper presents a new version of a coplanar waveguide that transmits a left-handed wave. The equivalent circuit of the line unit cell has been derived from the shape of the layout. The values of ...
New Bulk Metamaterial
Macháč, Jan; Buchar, Pavel; Zehentner, Ján; Omar, Abbas S.
2005 -
The design, analysis, fabrication and measurement of a new bulk metamaterial is reported in this paper. The structure of the new medium is made up of left-handed parallel strips. The series capacitors are realized by short circuited parallel strip stubs, and the conducting shunt pins represent parallel inductors. This metamaterial allows the propagation of a left-handed wave in the frequency band from 4.75 to 5.65 GHz, much wider than the frequency band achievable by split-ring resonators. The simple equivalent circuit of the metamaterial is derived. Additional modification of the media structure is proposed.
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
New Bulk Metamaterial
The design, analysis, fabrication and measurement of a new bulk metamaterial is reported in this paper. The structure of the new medium is made up of left-handed parallel strips. The series capacitors ...
Planar Transmission Lines in MW and MMW Circuits
Zehentner, Ján; Macháč, Jan; Mrkvica, Jan
2005 -
The analysis of open, particularly slotted planar transmission lines in a wide frequency range is presented in this paper. The full wave approach by the spectral domain method is applied. Theoretical findings and their practical consequences are reported. Some outputs from the CST microwave studio and from our analysis of planar transmission Lines package are shown.
Klíčová slova:
planar transmission lines; spectral domain method; dispersion characteristics; bound waves; leaky waves
Plné texty jsou dostupné v digitálním repozitáři ČVUT.
Planar Transmission Lines in MW and MMW Circuits
The analysis of open, particularly slotted planar transmission lines in a wide frequency range is presented in this paper. The full wave approach by the spectral domain method is applied. Theoretical ...
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