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Triple Wire Medium for Use in Isotropic Metamaterials
Hudlička, Martin; Macháč, Jan
2007 -
In this paper a triple wire medium is described as an isotropic negative permittivity medium. A numerical experiment was performed to validate the propagation of electromagnetic waves inside the wire lattice below the plasma frequency, where the effective medium permittivity is negative. For a practical realization, a form of the triple wire medium using a planar technology is proposed.
Available in digital repository of ČVUT.
Triple Wire Medium for Use in Isotropic Metamaterials
In this paper a triple wire medium is described as an isotropic negative permittivity medium. A numerical experiment was performed to validate the propagation of electromagnetic waves inside the wire ...
Improving Descriptors for Fast Tree Matching by Optimal Linear Projection
Mikolajczyk, Krystian; Matas, Jiří
2007 -
In this paper we propose to transform an image descriptor so that nearest neighbor (NN) search for correspondences becomes the optimal matching strategy under the assumption that inter-image deviations of corresponding descriptors have Gaussian distribution. The Euclidean NN in the transformed domain corresponds to the NN according to a truncated Mahalanobis metric in the original descriptor space. We provide theoretical justification for the proposed approach and show experimentally that the transformation allows a significant dimensionality reduction and improves matching performance of a state-of-the art SIFT descriptor. We observe consistent improvement in precision-recall and speed of fast matching in tree structures at the expense of little overhead for projecting the descriptors into transformed space. In the context of SIFT vs. transformed M- SIFT comparison, tree search structures are evaluated according to different criteria and query types. All search tree experiments confirm that transformed M-SIFTperforms better than the original SIFT.
Available in digital repository of ČVUT.
Improving Descriptors for Fast Tree Matching by Optimal Linear Projection
In this paper we propose to transform an image descriptor so that nearest neighbor (NN) search for correspondences becomes the optimal matching strategy under the assumption that inter-image ...
Linear Predictors for Fast Simultaneous Modeling and Tracking
Ellis, Liam; Dowson, Nicholas; Matas, Jiří; Bowden, Richard
2007 -
An approach for fast tracking of arbitrary image features with no prior model and no offline learning stage is presented. Fast tracking is achieved using banks of linear displacement predictors learnt online. A multi-modal appearance model is also learnt on-the-fly that facilitates the selection of subsets of predictors suitable for prediction in the next frame. The approach is demonstrated in real-time on a number of challenging video sequences and experimentally compared to other simultaneous modeling and tracking approaches with favourable results.
Available in digital repository of ČVUT.
Linear Predictors for Fast Simultaneous Modeling and Tracking
An approach for fast tracking of arbitrary image features with no prior model and no offline learning stage is presented. Fast tracking is achieved using banks of linear displacement predictors learnt ...
Isotropic Epsilon-Negative Particles
Macháč, Jan; Protiva, Pavel; Zehentner, Ján
2007 -
This paper presents two particles with negative permittivity in some frequency band. The response of a single dipole loaded by an inductance is strongly anisotropic. The response of a spider dipole does not depend on the orientation of the electric field of a wave being incident perpendicular to the particle substrate. These two particles are used in designing an isotropic epsilon-negative metamaterial. A unit cell of the metamaterial consists of a cube bearing the proposed particles on its faces, located with specific orientations. The experiments showed that only the single inductively loaded dipole is suitable for manufacturing of an isotropic epsilon-negative metamaterial. The isotropy of the new particles was checked by measurements.
Keywords:
ENG particle; isotropic metamaterial; negative permittivity
Available in digital repository of ČVUT.
Isotropic Epsilon-Negative Particles
This paper presents two particles with negative permittivity in some frequency band. The response of a single dipole loaded by an inductance is strongly anisotropic. The response of a spider dipole ...
Wetting Force Measurement of the Different Types of Solders and Testing Materials
Dušek, Karel; Urbánek, Jan; Mach, Pavel; Drápala, Jaromír
2007 -
We have used one of the most commonly used wetability evaluation methods -wetting balance (meniscograph) method to measure the wetting force. We have made a modification of the measuring equipment to measure a less quantity of the solder. We have measured a combination of different types of the lead and lead-free solders and different types of the testing materials. The measurement was carried out on nine different types of solders (Sn63Pb37, Sn95Sb5, Sn95Sb3,5Cul,5, Sn96Ag4, Sn95,5Ag3,8Cu0,7, Sn97Bi2Cul, Sn97Cu3, Sn99Cul, Sn99,75), three types of testing materials (copper, nickel and brass) and three types of fluxes. All measurements nine solders ware measured in ambient atmosphere and two lead-free solders were (Sn96Ag4, Sn95,5Ag3,8CuO,7) measured in inert atmosphere. The results of measurements we classified into the table according to he shape of wetting curve and according to the visual control.
Available in digital repository of ČVUT.
Wetting Force Measurement of the Different Types of Solders and Testing Materials
We have used one of the most commonly used wetability evaluation methods -wetting balance (meniscograph) method to measure the wetting force. We have made a modification of the measuring equipment to ...
Can Conductive Adhesives With Nanoparticles Beat Commonly Used Electrically Conductive Adhesives Without Nanoparticles
Bušek, David; Radev, Radoslav; Mach, Pavel
2007 -
This paper deals with electrically conductive adhesives (ECA's) with isotropic properties (ICA's) and describes the way of improving the quality parameters of such electrically conductive joint. This paper discusses the advantages and disadvantages of nanoparticle addition into commonly fabricated electrically conductive adhesive. Electrical parameters of ICA joints before and after mechanical, humid and humid-heat stress is applied, are observed. Standard controlling and evaluating principles for ECAs are based on resistance measurement of a joint; this paper shows that nonlinearity evaluation is more sensitive. For some applications, linearity might have crucial importance and an absolute size of resistance might not be so crucial. Our previous work proves that nonlinearity might not just be more sensitive but that it also does not have to progress in the same way as the resistivity (Busek, D. and Mach, P.).
Available in digital repository of ČVUT.
Can Conductive Adhesives With Nanoparticles Beat Commonly Used Electrically Conductive Adhesives Without Nanoparticles
This paper deals with electrically conductive adhesives (ECA's) with isotropic properties (ICA's) and describes the way of improving the quality parameters of such electrically conductive joint. This ...
Statistical Inspection of a Workplace for Adhesive Assembly
Mach, Pavel; Duraj, Aleš
2007 -
Quality of a workplace for adhesive assembly has been examined using acceptance sampling. The goal of the work has been to find our whether dispensing of electrically conductive adhesive makes forming of adhesive joints with sufficient reliability and repeatability possible. Adhesive joints have been fabricated by adhesive assembly of jumpers. Four types of adhesives, one of an acrylate type and three of an epoxy type with Ag filler have been used for testing. Joints resistances have been measured by a four-point method. Acceptance sampling by attributes has been used for statistical inspection. Acceptance plan has been calculated. It has been found that the workplace does not give results with sufficient quality.
Available in digital repository of ČVUT.
Statistical Inspection of a Workplace for Adhesive Assembly
Quality of a workplace for adhesive assembly has been examined using acceptance sampling. The goal of the work has been to find our whether dispensing of electrically conductive adhesive makes forming ...
Measurement of Nonlinearity as a Diagnostic Tool for Quality Determination of Lead-Free Solder Joints
Duraj, Aleš; Bušek, David; Mlích, Andrej
2007 -
At present there are directions RoHS-WEEE in European Union which restrict the use of certain hazardous substances in new electric and electronic products. Therefore mass usage of lead-free soldering in electronic production started. A typical alloy for lead-free soldering is based on Sn, Ag and Cu (SAC). For the most of types of lead-free solders is necessary to use technological process of soldering in reduced oxygen concentration atmosphere for improvement of wettability of soldered surfaces. Quality of these soldered joints is evaluated according of their electrical and mechanical properties. This paper is focused on measurement of nonlinearity, electrical resistance and mechanical strength. Especially evaluation of nonlinearity as a diagnostic tool for the prediction of solder joints reliability has been tested. Also effect of different surface finish of PCBs and influence of reduced oxygen concentration on quality of joints has been examined.
Available in digital repository of ČVUT.
Measurement of Nonlinearity as a Diagnostic Tool for Quality Determination of Lead-Free Solder Joints
At present there are directions RoHS-WEEE in European Union which restrict the use of certain hazardous substances in new electric and electronic products. Therefore mass usage of lead-free soldering ...
Electrically Loaded Adhesive Bonds Formed on Different Surfaces
Mach, Pavel; Radev, Radoslav
2007 -
Bonds of three types of electrically conductive adhesives with isotropic electrical conductivity have been formed on three types of surfaces - Cu; immerse Au and Sn (HAL). Epoxy resin types of adhesives with Ag flakes have been used. The bonds have been fabricated by assembly of jumpers. Two types of electrical load have been applied: DC current 1A and rectangular current pulses with the frequency of 500 Hz, mark-space ratio 1:1 and amplitude of 1A. The resistances, nonlinearity and noise of the bonds have been measured. It has been found that quality of the bonds on Sn surface finish is unacceptable through instability and level of measured parameters. The resistances and nonlinearity of the bonds formed on Au surface finish have been higher in comparison with those measured on Cu pads; noise have been comparable. Both types of the current load have caused low changes of all parameters tested.
Available in digital repository of ČVUT.
Electrically Loaded Adhesive Bonds Formed on Different Surfaces
Bonds of three types of electrically conductive adhesives with isotropic electrical conductivity have been formed on three types of surfaces - Cu; immerse Au and Sn (HAL). Epoxy resin types of ...
Wald’s Sequential Analysis for Time-constrained Vision Problems
Matas, Jiří; Šochman, Jan
2007 -
In detection and matching problems in computer vision, both classification errors and time to decision characterize the quality of an algorithmic solution. We show how to formalize such problems in the framework of sequential decisionmaking and derive quasi-optimal time-constrained solutions for three vision problems. The methodology is applied to face and interest point detection and to the RANSAC robust estimator. Error rates of the face detector proposed algorithm are comparable to the state-of-the-art methods. In the interest point application, the output of the Hessian-Laplace detector [9] is approximated by a sequential WaldBoost classifier which is about five times faster than the original with comparable repeatability. A sequential strategy based on Wald’s SPRT for evaluation of model quality in RANSAC leads to significant speed-up in geometric matching problems.
Available in digital repository of ČVUT.
Wald’s Sequential Analysis for Time-constrained Vision Problems
In detection and matching problems in computer vision, both classification errors and time to decision characterize the quality of an algorithmic solution. We show how to formalize such problems in ...
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