Wyniki wyszukiwania dla: SPAR PLATFORMS, HEAVE PLATES, DAMPING COEFFICIENT, ADDED MASS COEFFICIENT
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Application of Headspace Solid-phase Microextraction with Poly(1-vinyl-3- Hexylimidazolium Chloride) Polymeric Ionic Liquid Coating using GC - MS to Determine Volatile Fatty Acids in Dairy Wastewater
PublikacjaVolatile fatty acids were determined in this study using headspace solid-phase microextraction (HS-SPME) with a poly(1-vinyl-3-hexylimidazolium chloride) polymeric ionic liquid coated fiber followed by gas chromatography - mass spectrometry. Experimental parameters such as extraction time and temperature, sample volume as well as desorption time and temperature were optimized. Detection limits of the method were in the range of...
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Natural ventilation performance of family building in cold climate during windless time
PublikacjaIn this paper, the field measurements results are presented on the stack ventilation effect. The paper presents the results of performance (air change rate ACH) natural ventilation for building with inlet gap measured for the transitional season (between heating and summer season). The measurements were performed during a windless time. The house was located in northern Poland, in a cold climate region. The measurement system...
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Effect of pavement roughness and vehicle dynamic loads on decrease of fatigue life of flexible pavements
PublikacjaDue to the fact that pavement surfaces are not ideally even, dynamic loads of vehicle axles deviate from static loads. Higher dynamic loads contribute to faster pavement distress. The distribution of dynamic loads is similar to normal distribution and can be described by static load and factors DI (dynamic impact) and DLC (dynamic load coefficient). With the deterioration of pavement condition its evenness decreases as well and...
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Improvement of ships seakeeping performance by application of the Full-scale CFD simulations – case study
PublikacjaThe ship’s fuel economy is increasingly important. The paper presents the effect of redesigning a case study ship for increasing seakeeping performance. Selected wave parameters reflects very difficult operational con-ditions existing on the North Sea and the Baltic Sea. The analyzed variants of a case study ship represent the latest developments of modern hull forms. The concepts similar to V-shaped bulbous bow, X-bow, X-aft,...
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Wpływ kąta pochylenia koła na opór toczenia opon samochodowych
PublikacjaW pracy przedstawiono wpływ kąta pochylenia koła na opór toczenia opon do samochodów osobowych. Pomiary oporu toczenia kół toczących się z kątem pochylenia od -6º do +3º wykonano na bębnowej maszynie bieżnej metodą momentową. Wyniki pomiarów przedstawiono w formie zależności współczynnika oporu toczenia oraz przyrostu współczynnika oporu toczenia w funkcji kąta pochylenia badanego koła.
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Modified linear viscoelastic model of earthquake-induced structural pounding
PublikacjaIn recent times, earthquake-induced structural pounding has been intensively studied through the use of different impact force models. The numerical results obtained from the previous studies indicate that the linear viscoelastic model is relatively simple and accurate in modeling pounding-involved behavior of structures during earthquakes. The only shortcoming of the model is a negative value of the pounding force occurring just...
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Identification of ship’s hull mathematical model with numerical methods
PublikacjaThe modern maritime industry is moving toward the development of technology that will allow for full or partial autonomy of ship operation. This innovation places high demands on ship performance prediction techniques at the design stage. The researchwork presented in the article is related to the design stage of the ship and concerns methods for prognosis and evaluation of the specific operational condition of the ship, namely...
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Experimental investigation of forced convection of water/EGAl2O3 nanofluids inside horizontal tube
PublikacjaIn this paper, forced convection of water/EG-Al2O3 nanofluids inside horizontal stainless steel tube is studied experimentally. As base fluid served water/EG mixture of two ratios (60:50 and 50:50). Nanoparticle mass concentrations was 0.1% or and 1%. Transition and turbulent flow regimes were tested. Average heat transfer coefficient and pressure drop values were determined for nanofluids and compared to base fluids. Deterioration...
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Separation of C6 hydrocarbons on sodium dithionite reduced graphene oxide aerogels
PublikacjaThe ability of reduced graphene oxide aerogels (rGOAs) for challenging gas-phase separation was investigated with hexane isomers and benzene (C6 hydrocarbons) using inverse gas chromatography (IGC). For the first, rGOAs were synthesized with sodium dithionite (DTN) as a reductant. Experiments revealed that the most optimal DTN to graphene oxide mass ratio was 2:1, resulting in the highest specific surface area of 432.3 m2 g−1 and...
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Comparison of various flow maldistribution quantification methods in mini heat exchangers
PublikacjaThe aim of study is to compare various flow maldistribution quantification methods, using velocity, mass flow rate, pressure, and temperature. An experimentally validated numerical study has been prepared and a heat exchanger with 34 semi-circular channels with a diameter of 3.1 mm has been tested. The minichannels were heated from the bottom with a heat flux of 50, 60, 70, and 80 kW/m2. The cases for various inlet velocities of...
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The unstable thermoelectric effect in non-stoichiometric Cu2Se during the non-equilibrium phase transition
PublikacjaThe superionic α ↔ β phase transition in Cu1.96Se thermoelectric material is investigated by means of thermal analysis (DSC) and measurements of Seebeck coefficient and electrical conductivity. Results of the DSC measurements with 1–10 K/min heating and cooling rates show that the material is close to the equilibrium phase composition during the transformation. However, the kinetic limitation of the process exists, which is indicated...
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Comparative study of flow condensation in conventional and small diameter tubes
PublikacjaFlow boiling and flow condensation are often regarded as two opposite or symmetrical phenomena, however their description with a single correlation has yet to be suggested. In the case of flow boiling in minichannels there is mostly encountered the annular flow structure, where the bubble generation is not present. Similar picture holds for the case of inside tube condensation, where annular flow structure predominates. In such...
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A Method for Optimising the Blade Profile in Kaplan Turbine
PublikacjaThis paper introduces a method of blade profile optimisation for Kaplan-type turbines, based on modelling the interaction between rotor and stator blades. Rotor and stator blade geometry is described mathematically by means of a midline curve and thickness distribution. Genetic algorithms are then used to find a global optimum that minimises the loss coefficient. This allows for variety of possible blade shapes and configurations....
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The Impact Of The Selected Parameters Of Fdm Manufacturing Technology On Tribological Performance Of Abs–Steel Pair Under Dry Friction
PublikacjaThe paper presents the result of tribological test of ABS and steel samples sliding under dry friction. Polymeric samples were manufactured of ABS material using FDM technology. Testing was carried out in unidirectional sliding in a ring-on-flat contact in a PT-3 tribometer. The scope of tested parameters included volumetric and mass wear, the friction coefficient, and polymeric specimen temperature. Polymeric specimens used in...
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Experimental Study of Polish Sausage Drying Kinetics and Contraction by Image Data Analysis
PublikacjaThe goal of this paper has been to add an experimental data set for drying a meat product and provide a comparison with well-established thin-layer drying models. This article presented experimental investigations on the convective drying of Polish sausage slices at a temperature of 40°C. Slices have been in the thickness of 3 to 8mm. Measurements of mass loss and size change were performed. The data have been presented in the...
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Calculation method for flow boiling and flow condensation of R134a and R1234yf in conventional and small diameter channels
PublikacjaThe paper presents the results of calculations performed using the authors’ model to predict the heat transfer coefficient during flow boiling for two refrigerants R134a and R1234yf. The experimental data from various past studies have been collected and the calculations have been conducted for the full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in-house...
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EXPERIMENTAL VERIFICATION OF THE METHOD OF FLOW BOILING AND FLOW CONDENSATION HEAT TRANSFER PREDICTION FOR SELECTED FLUIDS
PublikacjaIn the paper presented are the results of calculations using authors own model to predict heat transfer coefficient during flow boiling of different refrigerants. The experimental data from various research studies from literature were collected. Calculations were conducted for a full range of quality variation and a wide range of mass velocity. The aim of the study was to test the sensitivity of the in- house developed model....
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Spinning Fluids Reactor: A new design of a gas – liquid contactor
PublikacjaCurrent trends in chemical reactor design are based on adapting these to the requirements of a particular chemical process. Processes involving reactions between the gas and liquid phase in particular require precise adjustment of all parameters. The common denominator for most modern design solutions is enhancement of the mass transfer area and the overall volumetric mass transfer coefficient. Gas – liquid contactors evolved from...
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A simplified energy dissipation based model of heat transfer for post-dryout flow boiling
Publikacjamodel for post dryout mist flow heat transfer is presented based on considerations of energy dissipation in the flow. The model is an extension of authors own model developed earlier for saturated and subcooled flow boiling. In the former version of the model the heat transfer coefficient for the liquid singlephase convection as a reference was used, due to the lack of the appropriate model for heat transfer coefficient for the...
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Does migration lead to economic convergence in an enlarged European market?
PublikacjaThis paper examines the relationship between migration and convergence for the enlarged internal market of the European Union (EU27) for the period 1990-2007. The impact of migration on growth is estimated in two ways: by including the migration rate in a growth regression and examining its impact on the convergence coefficient; and from the actual coefficient on migration, which can be interpreted as the effect of migration on...
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Mesh dependence study for numerical assessment of hydrodynamic characteristics of windsurfing fin
PublikacjaThe presented research aims to assess the drag coefficient and lift coefficient versus angle of attack curves for windsurfing fin. Special attention in the research was being paid to the evaluation of the stall angle value. The angle of incidence for which the stall occurs was searched, and the sensitivity of the solution for the mesh resolution was studied. The mesh resolution sensitivity analysis was done by systematically decreasing...
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Modelowanie procesu wrzenia i kondensacji w rozszerzonym zakresie ciśnień zredukowanych
PublikacjaNiniejsza rozprawa doktorska ma na celu pokazanie wpływu uwzględnienia ciśnienia zredukowanego w analizowanym modelu opisują-cym współczynnik przejmowania ciepła na zbieżność z danymi eksperymentalnymi.Przedmiotem analizy jest półempiryczny model Mikielewicza w zastosowaniu do danych eksperymentalnych w kanałach konwencjonalnych i o małej średnicy płynów uznanych za perspektywiczne.W ramach realizowanych prac badawczych pozyskano...
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Experimental Study on the Effectiveness of Polyurethane Flexible Adhesive in Reduction of Structural Vibrations
PublikacjaThe aim of the present study is to consider the idea of using polyurethane flexible adhesive in to reduce the vibrations in structures exposed to dynamic loads and evaluate their damping properties in relation to large deformations. Firstly, two aluminium cantilever beams, simulating structural elements (without and with polyurethane layer in the form of tape), were analysed, in order to check the damping of the unconstrained polymer...
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Killing kinetics analysis of C-1311 derivative with octaarginine (Compound 1-R8) against Candida albicans
Dane BadawczeThe datasets contain the results of killing kinetics analysis of imidazoacridinone derivative and fluconazole against C. albicans ATCC 10231. The suspensions of Candida albicans ATCC 10231 cells (500 µL) in RPMI 1640 at cell density of 104 cells /mL were added to 500 µL of RPMI 1640 medium with various concentrations of the compounds, corresponding...
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Economics of credit scoring management
PublikacjaCredit scoring models constitute an inevitable element of modern risk and profitability management in retail financial lending institutions. Quality,or separation power of a credit scoring model is usually assessed with the Gini coefficient. Generally, the higher Gini coefficient the better, as in this way a bank can increase number of good customers and/or reject more bad applicants. In...
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EFFECT OF NANOFLUID CONCENTRATION ON TWO-PHASE THERMOSYPHON HEAT EXCHANGER PERFORMANCE
PublikacjaAn approach – relaying on application of nanofluid as a working fluid, to improve performance of the two-phase thermosyphon heat exchanger (TPTHEx) has been proposed. The prototype heat exchanger consists of two horizontal cylindrical vessels connected by two risers and a downcomer. Tube bundles placed in the lower and upper cylinders work as an evaporator and a condenser, respectively. Distilled water and nanofluid water-Al2O3...
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Optimal Rotating Receiver Angles Estimation for Multicoil Dynamic Wireless Power Transfer
PublikacjaThis study proposed an approach to dynamic wireless charging that uses a rotating receiver coil. Our simulation study focused on the verification of a novel way of increasing the coupling coefficient and power transfer stability by following the flux of the transmitting coils. To obtain the highest possible coupling by means of the FEM analysis, we studied the optimization of the trajectory of the angular velocity of the rotating...
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Simplified saturation modelling in three-leg power transformer for the system stability analisys
PublikacjaThe paper presents a simplified method for modelling non-linearity of the magnetic circuit of the power transformer. The saturation effect is implemented by describing the self and mutual inductances as a function of the magnetic flux. The most important element of this function is the saturation coefficient which is calculated based on transient state during the unloaded transformer switch on. The transformer model is described...
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Structural optimization of microjet array cooling system
PublikacjaThe single phase heat transfer from an upward facing, horizontal copper surface to arrays of impinging water jets was experimentally investigated. Experimental configuration allows for a free-surface unconfined jets flow. Square nozzles 50 × 100 μm arranged in four different geometries were used. Additionally, for the set of two jets array geometry was varied by adjusting the nozzle to nozzle distance. The area averaged heat transfer...
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Measurement of mass flow of viscous liquid through a Cylindrical Orifice under laminar flow (CylOr)
Dane BadawczeThe data was obtained as part of the project "Measurement of mass flow of viscous liquid through a Cylindrical Orifice under laminar flow (CylOr)", in which flow tests of hydraulic oil through a cylindrical orifice with a thickness of l = 25 mm and a throat b = 0.5 (diameter pipes D = 50 mm, orifice diameter d = 25 mm) on the test stand at the Department...
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Applicability of arrays of microjets heat transfer correlations to design compact heat exchangers
PublikacjaThe article presents experimental studies on a compact heat exchanger with heat transfer intensification by means of impinging microjets. The pursuit to provide high performance of heat exchangers is a response to the demand both in economics and in the universal tendency to miniaturization of industrial equipment. This paper presents the design and tests of a prototype, microjet heat exchanger. The modular design of the heat exchanger...
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A simplified energy dissipation based model of heat transfer for subcooled flow boiling
PublikacjaIn the paper a model is presented based on energetic considerations for subcooled flow boiling heat transfer. The model is the extension of authors own model developed earlier for saturated flow boiling and condensation. In the former version of the model we used the heat transfer coefficient for the liquid single-phase as a reference level, due to the lack of the appropriate model for heat transfer coefficient for the subcooled...
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On Nonlinear Dynamic Theory of Thin Plates with Surface Stresses
PublikacjaWe discuss the modelling of dynamics of thin plates considering surface stresses according to Gurtin–Murdoch surface elasticity. Taking into account the surface mass density we derive the two-dimensional (2D) equations of motion. For the reduction of the three-dimensional (3D) motion equations to the 2D ones we use the trough-the-thickness integration procedure. As a result, the 2D dynamic parameters of the plate depend not only...
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Numerical simulation of cold flow and combustion in a swirl stabilized combustor
PublikacjaA numerical simulation model was developed to investigate the cold flow and combustion using Ansys FLUENT 2021R1. The governing equations were solved using the pressure-based method, and pressure–velocity coupling was performed using the SIMPLE method. To model the turbulent process, the RSM model was used. Non-premixed model is chosen to solve the chemical kinetics between fuel and oxigen. Radiation heat transfer was calculated...
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The experimental identification of the dynamic coefficients of two hydrodynamic journal bearings operating at constant rotational speed and under nonlinear conditions.
PublikacjaHydrodynamic bearings are commonly used in ship propulsion systems. Typically, they are calculated using numerical or experimental methods. This paper presents an experimental study through which it has been possible to estimate 24 dynamic coefficients of two hydrodynamic slide bearings operating under nonlinear conditions. During the investigation, bearing mass coefficients are identified by means of a newly developed algorithm....
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Experimental study of flow boiling pressure drop and heat transfer of R1233zd(E) at moderate and high saturation temperatures
PublikacjaThe paper presents the results of experimental study of flow boiling of R1233zd(E) in minichannel at moderate and high saturation temperatures. The heat transfer coefficient and pressure drop were measured for flow boiling in a stainless steel tube with 2 mm inside diameter and a length of 300 mm. Experiment has been conducted for saturation temperatures ranging from 83 to 145 °C which corresponds to values of reduced pressures...
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Subcritical bifurcation of free elastic shell of biological cluster
PublikacjaIn this paper we will investigate symmetry-breaking bifurcation of equilibrium forms of biological cluster. A biological cluster is a two-dimensional analogue of a gas balloon. The cluster boundary is connected with its kernel by elastic links. The inside part is filled with compressed gas or fluid. Equilibrium forms of biological cluster can be found as solutions of a certain second order ordinary functional-differential equation...
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AKUSTYCZNY ASPEKT ZASTOSOWANIA BLACHY KORTENOWEJ W EUROPEJSKIM CENTRUM SOLIDARNOŚCI W GDAŃSKU
PublikacjaArtykuł opisuje użycie blachy kortenowej jako dominującego materiału wykończeniowego na elewacjach i we wnętrzach budynku o przesłaniu symbolicznym. Przedstawiono architektoniczne przesłanki, uzasadniające jednorodność zastosowanego materiału. Na tym tle omówiono wpływ blachy kortenowej na akusty-kę pomieszczeń, wraz z podaniem kroków zaradczych redukujących nadmierną pogłosowość i zwiększających stopień rozproszenia dźwięku. Pozytywnym...
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Mitigation of the Flow Maldistribution in Minichannel and Minigap Heat Exchangers by Introducing Threshold in the Manifolds
PublikacjaIn the present paper, a detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel rectangular cross-section (1 mm depth and 1 mm width) minichannels and minigap section (1 mm depth and 99 mm width) with rectangular/trapezoidal manifolds in Z-type flow configuration. The author carried out numerical investigation with various mass flowrates, namely 0.05 kg/s, 0.1 kg/s and 0.2 kg/s which...
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Heat transfer in plate heat exchanger channels: experimental validation of selected correlation equations
PublikacjaThis study is focused on experimental investigation of selected type of brazed plate heat exchanger. The Wilson approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The...
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Straightened characteristics of McKendrick-von Foerster equation
PublikacjaWe study the McKendrick-von Foerster equation with renewal (that is the age-structured model, with total population dependent coefficient and nonlinearity). By using a change of variables, the model is then transformed to a standard age-structured model in which the total population dependent coefficient of the transport term reduces to a constant 1. We use this transformation to get existence, uniqueness of solutions of the problem...
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Heat transfer in plate heat exchanger channels: experimental validation of selected correlation equations
PublikacjaThis study is focused on experimental investigation of selected type of brazed plate heat exchanger. The Wilson approach was applied in order to estimate heat transfer coefficients for the PHEx passages. The main aim of the paper was to experimentally check ability of several correlations published in the literature to predict heat transfer coefficients by comparison experimentally obtained data with appropriate predictions. The...
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SFEM Analysis of Beams with Scaled Lengths including Spatially Varying and Cross-Correlated Concrete Properties
PublikacjaThis paper presents the results obtained for plain concrete beams under four-point bending with spatially varying material properties. Beams of increasing length but constant depth were analyzed using the stochastic finite element method. Spatial fluctuation of a uniaxial tensile strength, fracture energy and elastic modulus was defined within cross-correlated random fields. The symmetrical Gauss probability distribution function...
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Manoeuvring forces on azimuthing podded propulsor model
PublikacjaThis paper presents the preliminary part of comprehensive manoeuvring open- water tests of a gas carrier model. The paper focuses on open water experiments with an azimuthing podded propulsor. The test program was carried out in the cavitation tunnel and the large towing tank of Ship Hydromechanics Division, Ship Design and Research Centre, Gdańsk. The pod was tested as a pushing unit with a 161.3 mm diameter propeller. Steering...
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Nanoparticle-free tissue-mimicking phantoms with intrinsic scattering
PublikacjaWe present an alternative to the conventional approach, phantoms without scattering nanoparticles, where scattering is achieved by the material itself: spherical cavities trapped in a silicone matrix. We describe the properties and fabrication of novel optical phantoms based on a silicone elastomer polydimethylsiloxane (PDMS) and glycerol mixture. Optical properties (absorption coefficient µa, reduced scattering coefficient µs',...
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Multistage generalized adaptive notch filter with improved accuracy
PublikacjaGeneralized adaptive notch filters (GANFs) are estimators of coefficients of quasi-periodically time-varying systems. Current state of the art GANFs can deliver highly accurate estimates of system variations’ frequency, but underperform in terms of accuracy of the coefficient estimates. The paper proposes a novel multistage GANF with accuracy improved in this aspect. The processing pipeline consists of three stages. The preliminary...
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Microstructure and Electrical Properties of Fe,Cu Substituted (Co,Mn)3O4 Thin Films
PublikacjaIn this work, thin films (~1000 nm) of a pure MnCo2O4 spinel together with its partially substituted derivatives (MnCo1.6Cu0.2Fe0.2O4, MnCo1.6Cu0.4O4, MnCo1.6Fe0.4O4) were prepared by spray pyrolysis and were evaluated for electrical conductivity. Doping by Cu increases the electrical conductivity, whereas doping by Fe decreases the conductivity. For Cu containing samples, rapid grain growth occurs and these samples develop cracks...
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Mechanical properties of sisal fiber-reinforced soybean oil-based polyurethane biocomposites
PublikacjaIn this paper the results of the mechanical properties of polyurethane biocomposites reinforced with short sisal fibers are presented. The fillers were added in different amount: 5, 10 and 15% by mass. Tensile test, hardness, abrasion resistance, elasticity were determined according to the standards.
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Experimental investigation on straight and u-bend double tube heat exchanger with active and passive enhancement methods
PublikacjaAuthors in this work want to demonstrate the possibility to increase the heat transfer efficiency by using simple wire coil inserts to create turbulent flow in the boundary layer as well as air blowing into the annulus of the pipe. In the study, Wilson plot approach was applied in order to estimate heat transfer coefficients for all heat exchanger (HX) configurations. The study focuses on experimental values of heat transfer coefficient...
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In Vitro Studies on the Relationship Between the Antioxidant Activities of Some Berry Extracts and Their Binding Properties to Serum Albumin
PublikacjaThe aim of this study was to investigate the possibility to use the bioactive components from cape gooseberry (Physalis peruviana), blueberry (Vaccinium corymbosum), and cranberry (Vaccinium macrocarpon) extracts as a novel source against oxidation in food supplementation. The quantitative analysis of bioactive compounds (polyphenols, flavonoids, flavanols, carotenoids, and chlorophyll) was based on radical scavenging spectrophometric assays...