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A semi-empirical model for flow boiling heat transfer with account of the reduced pressure effect
PublikacjaIn the present study the attention was focused on the influence of reduced pressure on the predictions of heat transfer during flow boiling at the extensive range of pressures. The results of calculations were to test the sensitivity of the in-house flow boiling model with respect to the selection of the appropriate two-phase flow multiplier, which is one of the distinctive elements of that model. For this purpose a few two-phase...
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STRATEGIA DOBORU PROCESU PRODUKCYJNEGO WG. REAKCJI NA ZAMÓWIENIA KLIENTA
PublikacjaW opracowaniu poruszono zagadnienie doboru strategii wytwarzania w zakresie procesu produkcyjnego. W ramach tego zagadnienia dokonano podziału procesów produkcyjnych wg różnych kryteriów. Skupiano się na podziale procesów wg. reakcji na zamówienia klienta. Przedstawiono pokrótce najistotniejsze cechy charakteryzujące tego typu procesy. By móc określić strategię w zakresie procesu produkcyjnego zestawiono kryteria wyboru procesu...
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Residual current devices in installations with PV energy sources
PublikacjaThe paper presents the principles of residual current devices (RCDs) application in photovoltaic (PV) installations. Provisions of standards in this regard are commented on, in particular, attention is drawn to the lack of obligation to use of RCDs in PV installations. The issue of the shape of the earth fault current and the level of leakage currents in such installations are discussed. These factors influence the selection of...
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Sensorless predictive control of three-phase parallel active filter
PublikacjaThe paper presents the control system of parallel active power filter (APF) with predictive reference current calculation and model based predictive current control. The novel estimator and predictor of grid emf is proposed for AC voltage sensorless operation of APF, regardless of distortion of this voltage. Proposed control system provides control of APF current with high precision and dynamics limited only by filter circuit parameters....
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Space-mapping-based design flow of miniaturized broadband matching transformer with perforated metallization
PublikacjaA fast design procedure of unconventional passive components has been presented and experimentally validated on the basis of a wideband microstrip four-section matching transformer (50:6 OHm). A classic impedance matching circuit has been miniaturized by means of compact microstrip resonant cells (CMRCs) leading to a considerable length reduction (34%) together with minor degradation in its performance. The spacemapping-based design...
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Expedited Multi-Objective Design Optimization of Miniaturized Microwave Structures Using Physics-Based Surrogates
PublikacjaIn this paper, a methodology for fast multi-objective design optimization of compact microwave circuits is presented. Our approach exploits an equivalent circuit model of the structure under consideration, corrected through implicit and frequency space mapping, then optimized by a multi-objective evolutionary algorithm. The correction/optimization of the surrogate is iterated by design space confinement and segmentation based on...
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A High-Efficient Low-Voltage Rectifier for CMOS Technology
PublikacjaA new configuration of rectifier suiting CMOS technology is presented. The rectifier consists of only two nchannel MOS transistors, two capacitors and two resistors; for this reason it is very favourable in manufacturing in CMOS technology. With these features the rectifier is easy to design and cheap in production. Despite its simplicity, the rectifier has relatively good characteristics, the voltage and power efficiency, and...
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Left-handed propagation characteristics of a dielectric and metal-loaded periodic circular waveguide
PublikacjaIn this paper, a periodic dielectric/metallic rod is located in a circular waveguide to obtain left-handed operation. Two geometries of the dielectric/metallic rod are proposed and examined. The dispersion characteristics of the investigated waveguides are obtained using a surface impedance model. Moreover, equivalent circuit models are proposed allowing for calculation of the dispersion characteristics and scattering parameters...
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Model of noise sources in supercapacitors
PublikacjaThe paper presents detailed model of noise sources in supercapacitors. Noise phenomena observed in supercapacitors may be used as a diagnostic tool for assessment of supercapacitor quality or degradation mechanisms (e.g. corrosion of the electrodes or cloggin g up the pores) during ageing. Therefore, it is important to consider where noise is generated. The equivalent circuit of noise sources existing...
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Bias-Dependent Dynamics of Degradation and Recovery in Perovskite Solar Cells
PublikacjaDegradation of perovskite solar cells (PSCs) is often found to be partially or fully reversible when the cells are allowed to recover in the dark. Unlike the dynamics of degradation, knowledge about the dynamics of PSC cell recovery is very limited. Here, we demonstrate that the PSC recovery strongly depends on the electrical bias conditions during the light-induced degradation and that it can be manipulated by applying an external...
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Hybrid P3HT: PCBM/GaN nanowire/Si cascade heterojunction for photovoltaic application
PublikacjaPoly(3-hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) are commonly used for the fabrication of organic photovoltaics (OPV). Efficiency limitations of OPVs could be circumvented by incorporation of inorganic nanostructures into organic blends. Again, integration of organic solar cells with well-developed silicon photovoltaic technology is ultimately desirable. In present work, GaN nanowires with diameters...
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Low-Cost Automated Design of Compact Branch-Line Couplers
PublikacjaBranch-line couplers (BLCs) are important components of wireless communication systems. Conventional BLCs are often characterized by large footprints which make miniaturization an important prerequisite for their application in modern devices. State-of-the-art approaches to design of compact BLCs are largely based on the use of high-permittivity substrates and multi-layer topologies. Alternative methods involve replacement of transmission-line...
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Visual measurement system for chosen parameters of current collectors
PublikacjaA current collector is an element in a traction vehicle, used for movable, contact con-nection between the main circuit of this vehicle and the contact line. Bad technical condi-tion of these important elements in the main circuit of the vehicle result in its incorrect cooperation with contact line. Periodic control of technical condition of current collectors ensures infallible current collection. The pantograph diagnostics consists...
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Nonlinear secondary arc model use for evaluation of single pole auto-reclosing effectiveness
PublikacjaPurpose – The purpose of this paper is to discuss two evaluation methods of single pole autoreclosing process effectiveness in HV transmission lines. Secondary arc current and recovery voltage results obtained by load flow calculation are compared to the results obtained by the time domain simulations. Moreover, a nonlinear secondary arc implementation is presented. Design/methodology/approach – A computer simulation studies were...
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Study of Slip Effects in Reverse Roll Coating Process Using Non-Isothermal Couple Stress Fluid
PublikacjaThe non-isothermal couple stress fluid inside a reverse roll coating geometry is considered. The slip condition is considered at the surfaces of the rolls. To develop the flow equations, the mathematical modelling is performed using conservation of momentum, mass, and energy. The LAT (lubrication approximation theory) is employed to simplify the equations. The closed form solution for velocity, temperature, and pressure gradient...
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The Design of Cavity Resonators and Microwave Filters Applying Shape Deformation Techniques
PublikacjaThis article introduces shape deformation as a new approach to the computer-aided design (CAD) of high-frequency components. We show that geometry deformation opens up new design possibilities and offers additional degrees of freedom in the 3-D modeling of microwave structures. Such design flexibility is highly desirable if the full potential of additive manufacturing (AM) is to be exploited in the fabrication of RF and microwave...
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Accurate simulation-driven modeling and design optimization of compact microwave structures
PublikacjaCost efficient design optimization of microwave structures requires availability of fast yet reliable replacement models so that multiple evaluations of the structure at hand can be executed in reasonable timeframe. Direct utilization of full-wave electromagnetic (EM) simulations is often prohibitive. On the other hand, accurate data-driven modeling normally requires a very large number of training points and it is virtually infeasible...
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A Broadband Circularly Polarized Wide-Slot Antenna with a Miniaturized Footprint
PublikacjaThis letter presents a novel and simple feeding technique for exciting orthogonal components in a wide-slot antenna. In this technique, a rectangular bracket-shape parasitic strip is placed at the open end of the straight microstrip line to excite the fundamental horizontal and vertical components of the circular polarization (CP). The proposed technique—when employed in conjunction with the asymmetrical geometry of coplanar waveguide...
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Channel Blockage and Flow Maldistribution during Unsteady Flow in a Model Microchannel Plate heat Exchanger
PublikacjaThis paper describes the problem of channel blockage as a result of flow maldistribution between the channels of a model mini channel plate heat exchanger consisting of one pass on each leg. Each leg of the heat exchanger contains 51 parallel and rectangular minichannels of four hydraulic diameters namely 461 μm, 571 μm, 750 μm and 823 μm. In addition, a more complex geometry has been investigated where for the sake of breaking...
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Parallel immune system for graph coloring
PublikacjaThis paper presents a parallel artificial immune system designed forgraph coloring. The algorithm is based on the clonal selection principle. Each processor operates on its own pool of antibodies and amigration mechanism is used to allow processors to exchange information. Experimental results show that migration improves the performance of the algorithm. The experiments were performed using a high performance cluster on a set...
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Reply to Maarit Johnson's Letter to the Editor
PublikacjaWe wrote in response to the Letter to the Editor from Maarit Johnson regarding our article “Exploring the factor structure and the validity of the abbreviated Basic and Earning self-esteem Scales” (Dåderman & Basinska, 2013). We discussed two main issues: (a) the theory underlying the development of the longer (i.e., original) versions of the Basic and Earning SES, as well as the role of earning SE; and (b) the selection of items...
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Design and simulation of a new prototype of piezoelectric cantilever sensor/actuator for analysis of the soft tissues properties
PublikacjaThis paper is devoted to a new prototype of piezoelectric cantilever transducer dedicated for the characterization of the mechanical properties of soft tissues. General description of the actuator’s structure is presented including the basic principles of the measurement. The chosen geometry of the prototype is discussed and compared with the existing one. Constitutive equations are presented for the active and passive layer of...
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A new prototype of piezoelectric bending resonant transducer for analysis of soft tissues properties
PublikacjaThis paper is devoted to a new piezoelectric bending resonant transducer prototype dedicated to the characterization of the mechanical properties of soft tissue. A general description of the actuator’s structure is presented including the basic principles of the measurement. The chosen geometry of the prototype is discussed and compared with the existing version. Constitutive equations are presented for the active and passive layer...
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Badania wytrzymałościowe zgrzein łączących pręty zbrojeniowe o średnicy Ø30mm
PublikacjaZakres badań dotyczy oceny wytrzymałościowej zgrzein doczołowych, wykonanych metodą zwarciową. Elementami zgrzewanymi były pręty zbrojeniowe o średnicy Ø30mm. Badania związane są z okresową kontrolą stabilności parametrów zgrzewarki, szczególnie w odniesieniu do górnych, dopuszczalnych przez producenta zakresów parametrów zgrzewania oraz analizą wyników i porównaniu rezultatów prób wytrzymałościowych uzyskanych w 2019 i 2020 w...
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Syntetyczne wskaźniki oceny stanu toru
PublikacjaJakość geometryczna toru analizowana jest w różnych celach, a dane podlegają różnemu stopniowi agregacji. Pojedyncze nierówności toru analizowane są zazwyczaj z uwagi na bezpieczeństwo i służą do planowanie napraw w krótkich terminach. Natomiast agregacja pomierzonych parametrów pozwala na planowanie robót w terminach średniookresowych i budowę modeli predykcji. W artykule przedstawiono zagregowane wskaźniki jakości geometrycznej...
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DETEKCJA FAL UDERZENIOWYCH W UKŁADACH ŁOPATKOWYCH CZĘŚCI NISKOPRĘŻNYCH TURBIN PAROWYCH
PublikacjaW artykule przedstawiono wyniki numerycznych symulacji okołodźwiękowego przepływu pary przez ostatnie stopnie części niskoprężnej turbiny o mocy 50 MW. Celem przeprowadzonych symulacji była detekcja oraz lokalizacja fali uderzeniowej, występującej dla przyjętej geometrii układu łopatkowego. Przeanalizowano również wpływ zmiany wartości ciśnienia na wlocie do rozpatrywanych stopni turbiny na maksymalną wartość...
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Assessment of the Effective Variants Leading to Higher Efficiency for the Geothermal Doublet, Using Numerical Analysis‒Case Study from Poland (Szczecin Trough)
PublikacjaNumerical models of geothermal doublet allows us to reduce the high risk associated with the selection of the most eective location of a production well. Furthermore, modeling is a suitable tool to verify possible changes in operational geothermal parameters, which guarantees liveliness of the system. An appropriate selection of software as well as the methodology used to generate numerical models significantly aects the quality...
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KernelHive: a new workflow-based framework for multilevel high performance computing using clusters and workstations with CPUs and GPUs
PublikacjaThe paper presents a new open-source framework called KernelHive for multilevel parallelization of computations among various clusters, cluster nodes, and finally, among both CPUs and GPUs for a particular application. An application is modeled as an acyclic directed graph with a possibility to run nodes in parallel and automatic expansion of nodes (called node unrolling) depending on the number of computation units available....
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Comparison of predictive methods for flow boiling heat transfer in conventional channels and minichannels - the effect of reduced pressure
PublikacjaIn the paper are presented the results of follow on studies from [1]–[3] using authors own model to predict heat transfer coefficient during flow boiling. The model has been tested against a large selection of experimental data collected from various researchers to investigate the sensitivity of the in-house developed model. The collected experimental data came from various studies from literature and were conducted for the full...
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Noise measurements on low noise pavements - problems with inhomogeneity of wearing course
PublikacjaDuring the last several years, when performing numerous CPX noise measurements on low noise pavements,significant inhomogeneity of the wearing course was observed in numerous cases. Similar problems were almost not existing regarding to the dense pavements.In general three main reasons of inhomogeneity can be defined. The first one are imperfections in technology of production of a asphalt mix or/and errors made already during...
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Towards Contactless, Hand Gestures-Based Control of Devices
PublikacjaGesture-based intuitive interactions with electronic devices can be an important part of smart home systems. In this paper, we adapt the contactless linear gesture sensor for the navigation of smart lighting system. Set of handled gestures allow to propose two methods of active light source selection, continuous dimming, and turning on and off based on discrete gestures. The average gesture recognition accuracy was 97.58% in the...
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An Extended Control of the Input Angle for Matrix Converters Connected with the Non-Unity Power Factor Loads.
PublikacjaThis paper proposes a novel PWM modulation algorithm for Multiphase Conventional Matrix Converters (MCMC), with 3 inputs and k outputs, using the transfer function of the load angle. The proposed approach extends the range of power angle control at the input during the operation with a maximum voltage transfer ratio. The proposed concept is based on the Direct Analytic Voltage PWM (DAV--PWM) modulation with an elliptical trajectory...
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Impedance monitoring of corrosion degradation of plasma electrolytic oxidation coatings (PEO) on magnesium alloy
PublikacjaImpedance technique based on continuous multisinusoidal current perturbation was used to explain degradation process of plasma electrolytic oxidation coatings (PEO) on magnesium alloy. An obtained impedance spectrum was fitted by electrical equivalent circuit to describe properties of conversion layer on magnesium alloy. Additionally, galvanostatic mode maintained during experiment, with DC current equal to zero, allowed to achieve...
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Development of the sound field 3D intensity probe based on miniature microphones
PublikacjaThe engineered measuring probe uses three pairs of miniature microphones coupled. The signals from the microphones after an initial amplification are fed to differential circuits. Due to the required symmetry of the circuit it was necessary to select electronic components very carefully. Moreover, additional digital signal processing techniques were applied to avoid amplitude and phase mismatch. The view of the engineered probe...
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Resilient Routing in Communication Networks
PublikacjaThis important text/reference addresses the latest issues in end-to-end resilient routing in communication networks. The work highlights the main causes of failures of network nodes and links, and presents an overview of resilient routing mechanisms, covering issues related to the Future Internet (FI), wireless mesh networks (WMNs), and vehicular ad-hoc networks (VANETs). For each of these network architectures, a selection of...
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Piotr Płotka dr hab. inż.
OsobyPiotr Płotka otrzymał tytuł zawodowy magistra inżyniera w 1976 r., a stopień doktora w dyscyplinie elektronika w 1985 r. – nadane przez Wydział Elektroniki Telekomunikacji i Informatyki Politechniki Gdańskiej. W 2008 r. otrzymał stopień doktora habilitowanego, także w dyscyplinie elektronika, nadany przez Instytut Technologii Elektronowej w Warszawie. Od 1977 r. pracował w Akademii Techniczno-Rolniczej w Bydgoszczy, a od 1981...
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Trichloridobis(ethyldiphenylphosphine)-(tetrahydrofuran)molybdenum(III)
PublikacjaIn the mononuclear title compound, [MoCl3(C4H8O)(C14H15P)2], obtained by the reaction of trichlorotris(tetrahydrofuran)molybdenum(III) and ethyldiphenylphosphine in tetrahydrofuran (THF) solution, the MoIII atom is six-coordinated by one O atom of a THF molecule, two P atoms from two ethyldiphenylphosphine ligands and three Cl atoms in a distorted octahedral geometry. The C atoms of the THF molecule are disordered over two positions...
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Small Antenna Design Using Surrogate-Based Optimization
PublikacjaIn this work, design of small antennas using efficient numerical optimization is investigated. We exploit variable-fidelity electromagnetic (EM) simulations and the adaptively adjusted design specifications (AADS) technique. Combination of these methods allows us to simultaneously adjust multiple geometry parameters of the antenna structure of interest in a computationally feasible manner, leading to substantial reduction of the...
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Modelling of two-component turbulent mass and heat transfer in air-fed pressurised suits
PublikacjaIn this paper the modelling of an important industrial problem is addressed, which involves the two-component turbulent flow with heat transfer that takes place inside protective clothing. The geometry of the flow boundaries is reconstructed in a CAD system from photogrammetry scan data. The overall model is sufficiently realistic to allow, after validation, design improvements to be tested. Those presented here allow the reduction...
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Elektrolity stosowane w kondensatorach elektrochemicznych
PublikacjaPrzedstawiono trzy główne grupy elektrolitów ciekłych stosowanych w kondensatorach elektrochemicznych: elektrolity wodne, organiczne oraz ciecze jonowe. Przedstawiono ich właściwości, skład, problemy związane z użytkowaniem, a także najnowsze osiągnięcia w rozwoju poszczególnych grup elektrolitów ciekłych. Omówiono także dodatki do elektrolitów, ich rodzaje oraz wpływ na właściwości elektrolitu i pracę urządzenia.
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Effects of Noncontact Shoulder Tool Velocities on Friction Stir Joining of Polyamide 6 (PA6)
PublikacjaIn this study, the effects of the traverse and rotational velocities of the noncontact shoulder tool on the heat generation and heated flux during the friction stir joining of high-density polyamide 6 (PA6) polymer were investigated. The computational fluid dynamics (CFD) method was employed to simulate the thermomechanical phenomena during the friction stir joining (FSJ) process of PA6. A developed model was used to consider the...
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Retrievable strain measuring system in screw displacement piles - readings and results interpretation problems
PublikacjaStatic load tests on foundation piles are generally carried out in order to determine load – displacement characteristic of the pile. For more detailed information, e.g. force distribution along the shaft, load transfer mechanism and characteristics of soil-structure interaction (unit resistance curves t-z, q-z) additional pile instrumentation is required. Most popular techniques focus on direct concrete strain measurements and...
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Using the Fingerprinting Method to Customize RTLS Based on the AoA Ranging Technique
PublikacjaReal-time Locating Systems (RTLSs) have the ability to precisely locate the position of things and people in real time. They are needed for security and emergency applications, but also for healthcare and home care appliances. The research aims for developing an analytical method to customize RTLSs, in order to improve localization performance in terms of precision. The proposed method is based on Angle of Arrival (AoA), a ranging...
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Design of Structure of Tension Leg Platform for 6 MW Offshore Wind Turbine Based On Fem Analysis
PublikacjaThe article presents the calculation and design stages of the TLP platform serving as a supporting construction of a 6 MW offshore wind turbine. This platform is designed to anchor at sea at a depth of 60 m. The authors presented the method of parameterization and optimization of the hull geometry. For the two selected geometry variants, the load and motion calculations of the platform subjected to wind, wave and current under...
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Variable-fidelity response feature surrogates for accelerated statistical analysis and yield estimation of compact microwave components
PublikacjaAccounting for manufacturing tolerances is an essential part of a reliable microwave design process. Yet, quantification of geometry and/or material parameter uncertainties is challenging at the level of full-wave electromagnetic (EM) simulation models. This is due to inherently high cost of EM analysis and massive simulations necessary to conduct the statistical analysis. Here, a low-cost and accurate yield estimation procedure...
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The thermal effort during marine steam turbine flooding with water
PublikacjaThe work discussed an extreme case of cooling a steam turbine. The ship's steam turbine was used as an example. In marine transport units with low-speed engines dominate, however, there are also units with steam turbines. An example of analysed marine steam turbine is shown in Fig. 1. When considering the issue of cooling steam turbines, it is necessary to estimate the extreme conditions that may occur during operation of the turbine....
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The loop impedance measurement
Dane BadawczeThe loop impedance measurement
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Measuring pulse rate with a webcam — A non-contact method for evaluating cardiac activity
PublikacjaIn this paper the simple and robust method of measuring the pulse rate is presented. Elaborated algorithm allows for efficient pulse rate registration directly from face image captured from webcam. The desired signal was obtained by proper channel selection and principal component analysis. A developed non-contact method of heart rate monitoring is shown in the paper. The proposed technique may have a great value in monitoring...
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A Note on Knowledge Management Education: Towards Implementing Active Learning Methods
PublikacjaKnowledge Management as an area of education is still a big challenge for teachers and practitioners. Nevertheless, there are several useful teaching methods in active education, especially oriented towards courses where innovation and delivering dynamic knowledge are critical. The goal of the paper is to present and discuss criteria relevant in the selection of active educational methods supporting knowledge management courses....
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The impact of the shape of deep drilled well screen openings on the filtration process in full saturation conditions
PublikacjaThe authors propose a supplementary method of modelling seepage flow around the deep drilled well screen. The study applies 3D numerical modelling (FEM) in order to provide an in-depth analysis of the seepage process. The analysis of filtration parameters (flow distribution q(x,t) and pressure distribution p) was conducted using the ZSoil.PC software system. The analysis indicates that the shape of perforation is of secondary importance...