Filtry
wszystkich: 1728
wybranych: 1255
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: EARTH CURRENT,HIGH FREQUENCY,TRIPPING TEST,RCDS
-
Design of a SiC based triple active bridge ceil for a multi-megawatt DC-DC converter
PublikacjaThe paper describes the design methodology of a novel Triple Active Bridge cell used as the building block for modular DC-DC converters. The intended application is for Medium Voltage Direct Current grids, such as the DC collector for offshore wind farms. The latest generation of SiC MOSFET semiconductors is utilized to operate in the medium frequency range while optimizing the efficiency. The dimensioning of the main cell components,...
-
Current based Normalized Triple Covariance as a bearings diagnostic feature in induction motor
PublikacjaDiagnosis of induction motors, conducted remotely by measuring and analyzing the supply current is attractive with the lack of access to the engine. So far there is no solution, based on analysis of current, the credibility of which allow use in industry. Statistics of IM bearing failures of induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is so important. The article provides...
-
Current-based higher-order spectral covariance as a bearing diagnostic feature for induction motors
PublikacjaConducting the diagnosis of induction motors remotely by analyzing the supply current is an attractive prospect with the lack of access to the engine. Currently, there is no solution, based on analysis of the current, the credibility of which would allow its use in industry. The statistics of bearing failures in induction motors indicate that they constitute more than 40% of induction motor damage, therefore, bearing diagnosis...
-
Induction Motor Bearings Diagnostic Using MCSA and Normalized Tripple Covariance
PublikacjaDiagnosis of induction motors, conducted remotely by measuring and analyzing the supply current is attractive with the lack of access to the engine. So far there is no solution, based on analysis of current, the credibility of which allow use in industry. Statistics of IM bearing failures of induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is so important. The article provides...
-
Evaluation of Low Temperature Properties of Rubberized Asphalt Mixtures
PublikacjaThe paper presents low-temperature test results of asphalt mixtures designed with use of bitumen modified by crumb rubber and also SBS polymer. Laboratory tests were conducted on two types of asphalt mixtures for wearing course – stone matrix asphalt (SMA 8) and porous asphalt (PA 8). This paper presents results of the following laboratory tests at low temperatures: TSRST test, three point bending creep test, fracture toughness...
-
Review and evaluation of cold recycling with bitumen emulsion and cement for rehabilitation of old pavements
PublikacjaThe article presents Polish experience with cold recycling of asphalt pavements with theusage of bituminous emulsion and cement. In the 1990s numerous roads in Polandrequired immediate reinforcement due to their significant degradation. Implementation ofthe cold recycling technology was one of the solutions to this problem. Cold recycledmixtures containebeside the recycled asphalt pavement and aggregateetwo differenttypes of binding...
-
Activated Tungsten Inert Gas Weld Characteristics of P91 Joint for Advanced Ultra Supercritical Power Plant Applications
PublikacjaActivated Tungsten Inert Gas (A-TIG) welding, a variant of tungsten inert gas (TIG) welding, was used for welding P91. In Generation IV power plants, P91 welds are prone to premature failure due to the presence and formation of brittle phases and creep at high temperatures. When performing A-TIG welding, the flux composition plays a role in the reversal of the Marangoni flow in the weld pool, which ultimately determines the level...
-
Mapping of Flood-Prone Areas Utilizing GIS Techniques and Remote Sensing: A Case Study of Duhok, Kurdistan Region of Iraq
PublikacjaOne of the most common types of natural disaster, floods can happen anywhere on Earth, except in the polar regions. The severity of the damage caused by flooding can be reduced by putting proper management and protocols into place. Using remote sensing and a geospatial methodology, this study attempts to identify flood-vulnerable areas of the central district of Duhok, Iraq. The analytical hierarchy process (AHP) technique was...
-
Hysteresis modelling of a medium frequency single-phase transformer
PublikacjaThe article describes a feedback Preisach hysteresis model equivalent circuit implementation of a medium frequency single-phase transformer being a part of a high power and high efficiency DC-DC converter. The macroscopic models of magnetic hysteresis are introduced and the feedback Preisach model is selected for further analysis. The hysteresis model is developed for a prototype transformer and the hysteresis loops are compared...
-
Measurements of flicker noise in supercapacitor cells
PublikacjaFlicker noise (1/f-like noise) is often used to assess the quality of various materials and devices. This phenomenon has been observed in different electrochemical devices or reactions (e.g., smart windows, pitting corrosion events). In our exploratory studies we consider how to measure and utilize 1/f noise for the quality assessment of supercapacitors. This task requires special attention because of enormous capacitance of the...
-
Analysis of the Usefulness of Cheap Audio Recorders for Spectral Measurement of Environmental Noise
PublikacjaEnvironmental noise pollution is nowadays one of the most serious health threats. The impact of noise on the human body depends not only on the sound level but also on its spectral distribution. Reliable measurements of the environmental noise spectrum are often hampered by the very high price of top quality measuring devices. This paper explores the possibility of using much cheaper audio recorders for the frequency analysis....
-
Dynamic mass measurement in checkweighers using a discrete time-variant low-pass filter
PublikacjaConveyor belt type checkweighers are complex mechanical systems consisting of a weighing sensor (strain gauge load cell, electrodynamically compensated load cell), packages (of different shapes, made of different materials) and a transport system (motors, gears, rollers). Disturbances generated by the vibrating parts of such a system are reflected in the signal power spectra in a form of strong spectral peaks, located usually in...
-
Simulation of the Remanence Influence on the Transient States of the Single-Phase Transformer Including Feedback Preisach Model
PublikacjaThis paper presents the results of the experimental and simulation investigation concerning the influence of remanence in the core of a single-phase transformer at the no-load transient state. Experimental studies consisted of the discharge of the capacitor through the primary winding at several different values of the residual magnetic flux. The paper presents a model of the transformer test system, taking into account the magnetic...
-
Structural phase transitions in multicomponent La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) oxides
PublikacjaIn this work, the influence of compositional complexity on the structural and thermal properties of multicomponent rare-earth ortho-niobates from the La0.2Nd0.2Sm0.2Gd0.2RE50.2NbO4 (RE5 = Ho, Y, Tb, Eu, Pr) series have been investigated. Based on X-ray powder diffraction studies using synchrotron radiation, it was found that all tested materials were pure single-phase compositions and showed stability in the monoclinic I2/c crystal...
-
APPLICATION OF SATELLITE IMAGERY AND GIS TOOLS FOR LAND SURFACE TEMPERATURE ESTIMATION AND VERIFICATION
PublikacjaLand surface temperature (LST) plays an important role in many land-surface processes on regional as well on global scales. It is also a good indicator of energy flux phenomena and is used as a parameter in various Earth observation related studies. However, LST estimation based on processing and utilisation of satellite derived data constitutes several problems in terms of time limitations, accessibility, atmospheric influence...
-
Ancient settlements-atavistic solutions for present water supply and drainage problems engendered by urbanism
PublikacjaWater is the most valuable resource available on earth. Although it is present in abundance, its usable volume is very scarce. This is the reason behind the existence of both floods and droughts around the world. However, human settlements face water scarcity issues that are primarily engendered by improper town planning measures. To create a balance between the available fractions of water, it is therefore imperative to have proper...
-
Improving the accuracy of subgridding scheme in finite differences method based on Legendre polynomials expansion
PublikacjaIn this article the Legendre polynomials have been used to interpolate the field at the boundary of the meshes of different densities. The numerical verification of the proposed technique has been carried out in frequency domain. It has been shown that the accuracy of the presented method is very high and stable - the error monotonically decreases as a function of the refinement factor.
-
Napęd z silnikiem indukcyjnym i 4-gałęziowym falownikiem SiC do turbosprężarek powietrza ogniw paliwowych dużej mocy
PublikacjaWysoka cena ogniw paliwowych utrudnia ich szerokie zastosowanie w transporcie i przemyśle. Należy szukać możliwości obniżenia ich kosztu również poprzez obniżenie kosztu i zwiększenie wydajności urządzeń pomocniczych ogniwa paliwowego (Balance of the Plant). Autorzy proponują aby w napędzie sprężarki powietrza, zastosować wysokoobrotowy silnik indukcyjny, który jest tańszy od stosowanych obecnie silników PMSM. W referacie zaproponowano...
-
Polymer based thick films - material quality and interface resistance evaluation
PublikacjaThe properties of polymer based thick film layers mede using different resistive pastes and dipping silvers have been studied. The composite of carbon and graphite (C/Gr) conducting particles suspended in different polymer vehicles were used for preparation resistive layers. Interface resistance Rc created between dipping silver (DiAg) contact layer and resistive layer was determined from the surface potential distribution measurements...
-
Multifaceted Analyses of Four Different Prototype Lightweight Photovoltaic Modules of Novel Structure
PublikacjaDynamic growth of photovoltaic capacity in Poland encourages many entities to invest in photovoltaic systems. However, in the case of buildings with low roof-bearing capacity it can be problematic or even impossible to mount conventional PV modules due to their relatively high weight. Hence, the use of lightweight PV modules is a potential solution. In this paper four different prototype silicon lightweight modules of novel structure...
-
Novel Structure and EM-Driven Design of Small UWB Monopole Antenna
PublikacjaA novel structure of a small UWB monopole antenna is presented. In our approach, a compact size is achieved by means of a meander line for current path enlargement as well as the two parameterized slits that introduce additional degrees of freedom helping to ensure good impedance matching. The antenna design is carried out using surrogate-based optimization involving variable-fidelity EM simulations. This allows us to simultaneously...
-
A Concept and Design Optimization of Compact Planar UWB Monopole Antenna
PublikacjaA novel structure concept of a compact UWB monopole antenna is introduced together with a low-cost design optimization procedure. Reduced footprint is achieved by introduction of a protruded ground plane for current path increase and a matching transformer to ensure wideband impedance matching. All geometrical parameters of the structure are optimized simultaneously by means of surrogate based optimization involving variable-fidelity...
-
Effect of electrode resistance on admittance spectra of planar organic device carrying SCLC and on charge carrier mobility extracted from susceptance
PublikacjaThe work presents small signal admittance spectra of a sandwich system with thin organic layer carrying a space charge limited current. The effect of series resistance of electrodes on the spectra is discussed. Spectra of small signal capacitance are added to get more detailed insight. The analysis performed shows that the series resistance can affect both parts of small signal response within a whole range of frequency. Moreover,...
-
Calculation of Resonance in Planar and Cylindrical Microstrip Structures Using a Hybrid Technique
PublikacjaA hybrid technique was employed for the analysis of the resonance frequency of thin planar and cylindrical microstrip structures with the patches of arbitrary geometry. The proposed technique utilizes a combination of Galerkin’s moment method and a finite-element method (FEM). In this approach, an FEM is adopted to calculate the patch surface current densities, and a method of moments is utilized to calculate the resonance frequencies...
-
Resonance microstrip structure with patch of arbitrary convex geometry with the use of field matching technique
PublikacjaAn analysis of the resonance frequency problem of planar microstrip structure with patch of arbitrary convex geometry is presented. A full-wave analysis is employed utilizing a combination of Galerkin’s moment method and field matching technique. In this approach, a field matching technique is adopted to calculate the patch surface current densities, and next the method of moments is utilized to calculate resonance frequencies...
-
The Possibility of Phase Change Materials (PCM) Usage to Increase Efficiency of the Photovoltaic Modules
PublikacjaSolar energy is widely available, free and inexhaustible. Furthermore this source of energy is the most friendly to the environment. For direct conversion of solar energy into useful forms like of electricity and thermal energy, respectively photovoltaic cells and solar collectors are being used. Forecast indicate that the first one solution will soon have a significant part in meeting the global energy demand. Therefore it is...
-
Contact with coupled adhesion and friction: Computational framework, applications, and new insights
PublikacjaContact involving soft materials often combines dry adhesion, sliding friction, and large deformations. At the local level, these three aspects are rarely captured simultaneously, but included in the theoretical models by Mergel et al., (2019). We here develop a corresponding finite element framework that captures 3D finite-strain contact of two deformable bodies. This framework is suitable to investigate sliding friction even...
-
Rapid Microwave Design Optimization in Frequency Domain Using Adaptive Response Scaling
PublikacjaIn this paper, a novel methodology for cost-efficient microwave design optimization in the frequency domain is proposed. Our technique, referred to as adaptive response scaling (ARS), has been developed for constructing a fast replacement model (surrogate) of the high-fidelity electromagnetic-simulated model of the microwave structure under design using its equivalent circuit (low-fidelity model). The basic principle of ARS is...
-
Improving listeners' experience for movie playback through enhancing dialogue clarity in soundtracks
PublikacjaThis paper presents a method for improving users' quality of experience through processing of movie soundtracks. The dialogue clarity enhancement algorithms were introduced for detecting dialogue in movie soundtrack mixes and then for amplifying the dialogue components. The front channel signals (left, right, center) are analyzed in the frequency domain. The selected partials in the center channel signal, which yield high disparity...
-
EXAMINING INFLUENCE OF VIDEO FRAMERATE AND AUDIO/VIDEO SYNCHRONIZATION ON AUDIO-VISUAL SPEECH RECOGNITION ACCURACY
PublikacjaThe problem of video framerate and audio/video synchronization in audio-visual speech recogni-tion is considered. The visual features are added to the acoustic parameters in order to improve the accuracy of speech recognition in noisy conditions. The Mel-Frequency Cepstral Coefficients are used on the acoustic side whereas Active Appearance Model features are extracted from the image. The feature fusion approach is employed. The...
-
EXAMINING INFLUENCE OF VIDEO FRAMERATE AND AUDIO/VIDEO SYNCHRONIZATION ON AUDIO-VISUAL SPEECH RECOGNITION ACCURACY
PublikacjaThe problem of video framerate and audio/video synchronization in audio-visual speech recognition is considered. The visual features are added to the acoustic parameters in order to improve the accuracy of speech recognition in noisy conditions. The Mel-Frequency Cepstral Coefficients are used on the acoustic side whereas Active Appearance Model features are extracted from the image. The feature fusion approach is employed. The...
-
Effect of solar radiation on current-carrying capacity of PVC-insulated power cables – the numerical point of view
PublikacjaPower cables are usually buried in the soil, which results in their relatively high current-carrying capacity. However, there are cases in which the starting/final section of a cable line runs along a pole of an overhead power line. Power cables can be directly exposed to solar radiation then, and this negatively influences their current-carrying capacity as well as estimated life of the cables’ insulation. An analysis of thermal...
-
Influence of electric, magnetic and electromagnetic fields on the circadian system – current stage of knowledge
PublikacjaOne of the side effects of each electrical device work is the electromagnetic field generated near its workplace. All organisms, including humans, are exposed daily to the influence of different types of this field, characterized by various physical parameters. Therefore, it is important to accurately determine the effects of an electromagnetic field on the physiological and pathological processes occurring in cells, tissues and...
-
Model and laboratory simulation of a induction motor for diagnostic purposes
PublikacjaStatistics say that bearings are this part of induction motors which is most susceptible to damage. The equipment employed for bearing diagnostics usually makes use of vibrations as the criterion for technical condition of the bearings. A faulty bearing results in additional motor vibrations. They are reflected in the harmonic content of stator currents. In certain operating conditions the current signal is the sole source of information...
-
Evaluation of possibilities in identification and susceptibility testing for Candida glabrata clinical isolates with the Integral System Yeast Plus (ISYP)
PublikacjaThe aim of this study was to evaluate possibilities of correct identification and susceptibility testing of C. glabrata clinical isolates with Integral System Yeast Plus (ISYP). For species identification, as the reference method, API Candida test and species-specific PCR reactions were used. The potential of antifungal susceptibility testing by the ISYP test was compared with the Sensititre Yeast One. Whilst the reference methods...
-
MCSA with Normalized Triple Covariance as a bearings diagnostic indicator in an induction motor
PublikacjaStatistics of bearing failures in induction motors indicate, that they constitute more than 40% of IM damage, therefore bearing diagnosis is very important. Vibration methods for bearing diagnostics have one major disadvantage - they require the availability of the machine for sensors installation. This is the reason for seeking new methods based on motor supply current analysis. Diagnosis of induction motors, conducted remotely...
-
Stress Detection of Children With ASD Using Physiological Signals
PublikacjaThis paper proposes a physiological signal-based stress detection approach for children with autism spectrum disorder (ASD) to be used in social and assistive robot inter- vention. Electrodermal activity (EDA) and blood volume pulse (BVP) signals are collected with an E4 smart wristband from children with ASD in different countries. The peak count and signal amplitude features are derived from EDA signal and used in order to detect...
-
Study of oxygen electrode reactions on symmetrical porous SrTi0.30Fe0.70O3-δ electrodes on Ce0.8Gd0.2O1.9 electrolyte at 800 °C–500 °C
PublikacjaIron doped strontium titanates (SrTi1-xFexO3-δ) are an interesting mixed ionic-electronic conductor model used to study basic oxygen reduction/oxidation reactions. In this work, we performed an impedance spectroscopy study on symmetrical porous SrTi0.30Fe0.70O3-δ (STF70) electrodes on a ceriabased electrolyte. The sample was measured in varying oxygen concentration: from 0.3% to 100% in 800 °C - 500 °C temperature range. Low polarisation...
-
Analysis of thoracic regional impedance changes using PCA approach
PublikacjaA multichannel impedance and one lead electrocardiographic recording system has been developed. The impedance measurement unit is built using a four-electrode technique. It consists of a sinusoidal, 40 kHz, current source and five measurement channels. Circumferential current electrodes have been located at a neck and an abdomen. Voltagemeasurement disk electrodes formed five two-electrode measurement ports. The impedance change...
-
Predykcyjne sterowanie równoległym filtrem aktywnym ze sprzężeniem od prądu zasilającego
PublikacjaArtykuł przedstawia nowatorską strategię predykcyjnego sterowania równoległym energetycznym filtrem aktywnym (EFA). Proponowane sterowanie zawiera sprzężenie zwrotne od prądu zasilającego i wiąże zalety sterowania w układzie otwartym oraz zamkniętym – szybkość reakcji na zmianę prądu odbioru i bardzo wysoką skuteczność kompensacji. Wysoka jakość prądu kompensacyjnego wynika również z zastosowania w sterowaniu algorytmów predykcyjnych,...
-
A Parallax Shift Effect Correction Based on Cloud Height for Geostationary Satellites and Radar Observations
PublikacjaThe effect of cloud parallax shift occurs in satellite imaging, particularly for high angles of satellite observations. This study demonstrates new methods of parallax effect correction for clouds observed by geostationary satellites. The analytical method that could be found in literature, namely the Vicente et al./Koenig method, is presented at the beginning. It approximates a cloud position using an ellipsoid with semi-axes...
-
Low-Cost Quasi-Global Optimization of Expensive Electromagnetic Simulation Models by Inverse Surrogates and Response Features
PublikacjaConceptual design of contemporary high-frequency structures is typically followed by a careful tuning of their parameters, predominantly the geometry ones. The process aims at improving the relevant performance figures, and may be quite expensive. The reason is that conventional design methods, e.g., based on analytical or equivalent network models, often only yield rough initial designs. This is especially the case for miniaturized...
-
MECHANICAL PROPERTIES OF BOTTOM ASH – DREDGED MATERIAL MIXTURES IN LABORATORY TESTS
PublikacjaBottom ash from EC Gdańsk and dredged material taken from the mouth of The Vistula were mixed to form an engineering material used for dike construction. Mixtures with different bottom ash content were tested in laboratory to determine its basic physical and mechanical properties. The optimum bottom ash–dredged material mixture, built in the corps of the test dike, contains 70% of ash. The optimum bottom ash content in the mixture...
-
Influence of Added Water Mass on Ship Structure Vibration Parameters in Virtual and Real Conditions
PublikacjaModelling of ship structures in a virtual environment is now standard practice. Unfortunately, many engineers forget to consideri the influence of added water on the frequency values and the amplitude of natural vibrations. The article presents the effect of water damping on the frequency values of the individual natural vibration modes. The tests were carried out in two stages. First, the mentioned values were determined using...
-
Numerical and experimental investigation of thermal convection near electric devices with vertical channels
PublikacjaThis paper presents the results of numerical and experimental investigation of thermal convection near heat emitting surfaces of an electric device. For the intensification of thermal convection, special vertical channels were formed near the heat emitting surfaces of the device. An experimental test has proved that there is an optimal length of the channels – thermal convection is the most intensive then. Air velocity vectors...
-
Behavioral state classification in epileptic brain using intracranial electrophysiology
PublikacjaOBJECTIVE: Automated behavioral state classification can benefit next generation implantable epilepsy devices. In this study we explored the feasibility of automated awake (AW) and slow wave sleep (SWS) classification using wide bandwidth intracranial EEG (iEEG) in patients undergoing evaluation for epilepsy surgery. APPROACH: Data from seven patients (age [Formula: see text], 4 women) who underwent intracranial depth electrode...
-
Forced vibrations in a dynamic system that is damped by a mechanism that trans-pass through its singular position
PublikacjaIn the paper, vibrations of a hybrid multibody-continuous system are investigated. For all the mechanical devices, effective damping methods are crucial in the design process. To obtain it, installation of viscous dampers or elasto-viscous elements is dominant. In the paper, an alternative method is investigated. It is based on modal disparity. To describe the method briefly, when structural damping is present in continuous systems,...
-
The Influence of the Radio Channel on Precision of Position Estimation of the User Terminal Using the NB-IoT Radio Interface
PublikacjaIn the article the method of user terminal position estimation using the broadcast signals transmitted in the downlink of the NB-IoT interface was presented, including the analysis of the radio channel influence on precision of position estimation as well as the eNodeB (Evolved Node B) synchronization. The practical ability to estimate the position in the test area has been verified in the laboratory conditions, using the reference...
-
Overheating of underground power cable line due to its partial exposition to solar radiation
PublikacjaCurrent-carrying capacity of underground power cable lines depends, among others, on thermal resistivity of the soil and cables layout: trefoil formation, flat formation with or without spacing. If conditions for heat transfer in the ground are favorable, the current-carrying capacity is relatively high. Therefore, it generates risk of the power cables overheating, if part of the cable line is located vertically in the air, to...
-
Electrical properties of hybrid planar diode based on palladium phthalocyanine and titanium dioxide
PublikacjaThis work details experimental studies of a planar diode made of indium tin oxide/titanium dioxide/palladium phthalocyanine/gold. The rectification ratio of current was 105 at 1.5 V. The analysis of the electrical properties of the system was based on small signal complex capacitance spectra measured in the frequency range of 25 Hz-1 MHz at different values of bias. No depletion region at the TiO2/PdPc interface was observed. Forward...