Wyszukiwarka
prof. dr hab. inż. Krzysztof Tesch
Zatrudnienie
- Profesor w Instytut Energii
Publikacje
Filtry
wszystkich: 52
Katalog Publikacji
Rok 2024
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Effect of Vascular Lumen Reduction on the Performance and Energy Consumption of an Innovative Implantable LVAD
PublikacjaThis paper presents the results of a study on the effect of vascular lumen reduction on the performance of an innovative implantable LVAD (left ventricular assist device). It details the pressures in the individual cardiac chambers as a function of device frequency. In addition, mass flow rates and energy consumption of the device are examined, varying with lumen reduction and operating frequency. While the lumen reduction of the...
Rok 2023
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Experimental Investigation of the Performance of an Innovative Implantable Left Ventricular Assist Device—Proof of Concept
PublikacjaThis paper presents the results of experimental performance of an innovative left ventricular assist device working on a specially designed test stand. The introduced invention is mainly applied for supporting the heart in patients with end-stage heart failure accompanied by mitral valve regurgitation and pulmonary hypertension. Moreover, the developed device has the form of a flexible balloon forming an intracardiac inert gas-filled...
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Innovative Implantable Left Ventricular Assist Device—Performance under Various Resistances and Operating Frequency Conditions
PublikacjaThis paper presents the operation of an innovative left ventricular assist device under various resistances and operating frequencies. The operating principle of the device is based on pulsatile blood flow, which is forced by a suction–discharge device pumping helium into a set of intra-cardiac balloons. In this way, the ejection fraction of the left ventricle is increased, and the mitral valve is additionally occluded. What is...
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Numerical analysis of the ostiomeatal complex aeration using the CFD method
PublikacjaWe aimed to analyse ostiomeatal complex (OMC) aeration using the computational fluid dynamics (CFD) method of simulation based on human craniofacial computed tomography (CT) scans. The analysis was based on CT images of 2 patients: one with normal nose anatomy and one with nasal septal deviation (NSD). The Reynolds-Average Simulation approach and turbulence model based on linear eddy viscosity supplemented with the two-equation...
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Optimization of the distance between the vertical plates in the convective air heat exchanger
PublikacjaThis paper examines the influence of the distance between vertical plates on the intensity of free convective heat transfer along with the optimization of this distance. Experimental tests were carried out for one model channel of such an heat exchanger with widths , 0.085 and 0.18 m. This channel, open at the top and sides, was formed by two isothermal symmetrically heated parallel vertical plates of dimensions m and m. The influence...
Rok 2022
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Maxillary sinus aeration analysis using computational fluid dynamics
PublikacjaThe maxillary sinus aeration using the computational fluid dynamics (CFD) method based on individual adult patients’ computed tomography (CT) scans were analyzed. The analysis was based on CT images of 4 patients: one with normal nose anatomy and three with nasal septal deviation (NSD) and concha bullosa (CB). The CFD simulation was performed using the Reynolds-Average Simulation approach and turbulence closure based on linear...
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Method of reconstructing two-dimensional velocity fields on the basis of temperature field values measured with a thermal imaging camera
PublikacjaThis paper describes a novel numerical reconstruction procedure (NRP) of the velocity field during natural convective heat transfer from a two-sided, isothermal, heated vertical plate based only on the known temperature field obtained, e.g. with a thermal imaging camera. It has been demonstrated that with a knowledge of temperature distributions, the NRP enables the reconstruction of velocity fields by solving the Navier-Stokes...
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Verification of the method of reconstructing convective velocity fields on the basis of temperature fields in vertical, differential and equally heated, open and closed channels
PublikacjaThis paper describes a method of reconstructing velocity fields, i.e. a numerical reconstruction procedure (NRP) that involves the numerical processing of experimentally measured temperature distributions in free convection heat transfer. The NRP consists in solving only the continuity and Navier–Stokes equations with an additional source term. This term is proportional to a known temperature (e.g. from a thermal imaging camera)...
Rok 2021
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Mitigation effect of face shield to reduce SARS-CoV-2 airborne transmission risk: Preliminary simulations based on computed tomography
PublikacjaWe aimed to develop a model to quantitatively assess the potential effectiveness of face shield (visor) in reducing airborne transmission risk of the novel coronavirus SARS-CoV-2 during the current COVID-19 pandemic using the computational fluid dynamics (CFD) method. The studies with and without face shield in both an infected and healthy person have been considered in indoor environment simulation. In addition to the influence...
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Mitigation effect of face shield to reduce SARS-CoV-2 airborne transmission risk: Preliminary simulations based on computed tomography
PublikacjaWe aimed to develop a model to quantitatively assess the potential effectiveness of face shield (visor) in reducing airborne transmission risk of the novel coronavirus SARS-CoV-2 during the current COVID-19 pandemic using the computational fluid dynamics (CFD) method. The studies with and without face shield in both an infected and healthy person have been considered in indoor environment simulation. In addition to the influence...
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Numeryczna mechanika płynów
PublikacjaNumeryczna mechanika płynów
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The use of thermal imaging camera to estimate velocity profiles based on temperature distribution in a free convection boundary layer
PublikacjaThis work describes an attempt to assess whether the temperature field from a thermal imaging camera can be converted into a velocity field with an accuracy sufficient for qualitative conducting or describing the phenomenon, i.e. when the Navier-Stokes, Fourier-Kirchhoff and continuity equations are mutually coupled. The consequence of this link between temperature fields and velocity is the possibility to formulate the hypothesis...
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Three-dimensional modeling and automatic analysis of the human nasal cavity and paranasal sinuses using the computational fluid dynamics method
PublikacjaPurpose The goal of this study was to develop a complete workflow allowing for conducting computational fluid dynam- ics (CFD) simulation of airflow through the upper airways based on computed tomography (CT) and cone-beam computed tomography (CBCT) studies of individual adult patients. Methods This study is based on CT images of 16 patients. Image processing and model generation of the human nasal cavity and paranasal sinuses...
Rok 2019
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The Discrete-Continuous, Global Optimisation of an Axial Flow Blood Pump
PublikacjaThis paper presents the results of the discrete-continuous optimisation of an axial flow blood pump. Differential evolution (DE) is used as a global optimisation method in order to localise the optimal solution in a relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump are performed by means of the Reynolds-Average Navier-Stokes...
Rok 2018
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Discrete-continuous optimisation of an axial flow blood pump
PublikacjaThis paper presents results of discrete-continuous optimisation of an axial flow blood pump. Evolution Strategies (ES) are used as a global optimisation method in order to localise the optimal solution in relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump is performed by means of the Reynolds-Average Navier-Stokes...
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EXPERIMENTAL AND NUMERICAL VALIDATION OF THE IMPROVED VORTEX METHOD APPLIED TO CP745 MARINE PROPELLER MODEL
PublikacjaThe article presents a numerical analysis of the CP745 marine propeller model by means of the improved vortex method and CFD simulations. Both numerical approaches are validated experimentally by comparing with open water characteristics of the propeller. The introduced modification of the vortex method couples the lifting surface approach for the propeller blades and the boundary element method for the hub. What is more, a...
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Pre-swirl energy saving device in marine application
PublikacjaThis paper covers topics of energy saving device (ESD) with application to marine propulsors. The form of ESD, considered in this paper, consists of fixed lifting foils mounted in front of the screw propeller (the pre-swirl stator/guide vanes). An algorithm for designing propulsion systems, consisting of guide vanes and screw propeller, is presented. The proposed method relies on hybrid lifting line (guide vanes)-lifting surface...
Rok 2017
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A SHORT REVIEW OF BLOOD FLOW MODELLING METHODS: FROM MACRO- TO MICROSCALES
PublikacjaThe aim of this paper it to review various scale approaches to the blood flow modelling. Blood motion may be described by three types of mathematical models according to the observed scales or resolutions, namely microscopic, mesoscopic and macroscopic descriptions. The above approaches are discussed together with their advantages and disadvantages. Several results of mesoscopic simulations are presented with particular attention...
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Extended duration running and impulse loading characteristics of an acoustic bearing with enhanced geometry
PublikacjaThis paper presents performance during prolonged running of the acoustic bearing when PZTs are switched off and when they are switched on. The effect of active PZT on shaft’s displacements in X and Y directions is clearly demonstrated. Performance of the acoustic bearing was also assessed when an impulse force was applied to the running shaft at speed. Once again the benefits of having PZTs active are beyond doubt. The instability...
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Minimum drag shape bodies moving in inviscid fluid - revisited
PublikacjaThis paper presents the classic approach to minimum drag shape body problem, moving at hypersonic speeds, leading to famous power law shapes with value of the exponent of 3/4. Two- and three-dimensional cases are considered. Furthermore, an exact pseudo solution is given and its uselessness is discussed. Two new solutions are introduced, namely an approximate solution due to form of the functional and solution by means of optimisation...
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Turbomachinery - Background
PublikacjaThe "Turbomachinery - Background" is the first part of a series of monographs devoted to different aspects of rotating machines. The book presents the main fundamentals which are necessary for the different problems of steam, gas, wind and water turbines as well as pumps, compressors and propellers which will discussed in detail in the subsequent parts of the series.
Rok 2016
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Acoustic journal bearing – Performance under various load and speed conditions speed conditions
PublikacjaThe paper presents results of experimental testing aiming at finding out what effect system of piezo-electric actuators (PZTs)attached to an aerodynamic journal bearing has on the magnitude of shaft's motion within the bearing operating at specified speed and load. The results clearly demonstrate effectiveness of PZTs in mitigating the shaft's motion thus contributing to the increased stability of the bearing. This stabilizing...
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AN EXPERIMENTAL AND NUMERICAL STUDY ON THE PERFORMANCE OF AN INNOVATIVE VERTICAL-AXIS WIND TURBINE
PublikacjaThis paper introduces the innovative modification of the Savonius wind turbine being able to significantly increase efficiency in comparison with the classic design. This innovative design is equipped with a stator directing the flow. The presence of the stator increases the active surface area and generates higher torques acting on a shaft. Additionally, it makes it possible to take better advantage of wind energy and compensate...
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Arterial cannula shape optimization by means of the rotational firefly algorithm
PublikacjaThe article presents global optimization results of arterial cannula shapes by means of the newly modified firefly algorithm. The search for the optimal arterial cannula shape is necessary in order to minimize losses and prepare the flow that leaves the circulatory support system of a ventricle (i.e. blood pump) before it reaches the heart. A modification of the standard firefly algorithm, the so-called rotational firefly algorithm,...
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Continuous Optimisation Algorithms
PublikacjaKsiążka poświęcona jest zagadnieniom optymalizacji ciągłej. Oprócz klasycznych algorytmów gradientowych omawiane są w współczesne algorytmy bezgradientowe, które stosowane są z powodzeniem w optymalizacji globalnej. Większość prezentowanych algorytmów określona może być mianem metaheurystycznych. Zaliczyć do nich można metody optymalizacji inspirowane procesami zachodzącymi w przyrodzie, które dalej można dzielić na inspirowane...
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Laboratorium Mechaniki Płynów
PublikacjaKsiążka poświęcona jest zagadnieniom pomiarowym w mechanice płynów. Zawiera opis szeregu ćwiczeń laboratoryjnych związanych z przepływami. Książka przeznaczona jest dla studentów wydziałów mechanicznych i pokrewnych.
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Modelling of blood flow: from macro to microscales
PublikacjaThe aim of this paper it to review various scale approaches to blood flow modelling. Blood motion may be described by three types of mathematical models according to the observed scales or resolutions, namely microscopic, mesoscopic and macroscopic description. The above approaches are discussed together with their advantages and disadvantages. Several results of mesoscopic simulations are presented.
Rok 2015
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Acoustic journal bearing - A search for adequate configuration
PublikacjaClassical non-contact bearings are already used in a number of specialist applications but there are somespecialist areas where they cannot be used for variety of reasons and acoustic sliding bearings could be an alternative. The paper presents the quest for a configuration of an acoustic journal bearing and shows that the overall shape of the bearing and its geometry are of a vital importance for the load capacity oft he bearing....
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Investigation of the Aerodynamics of an Innovative Vertical-Axis Wind Turbine
PublikacjaThe paper presents the results of an experimental investigation and a three dimensional numerical analysis of the transient aerodynamic phenomena occurring in the innovative modification of classic Savonius wind turbine. An attempt to explain the increased efficiency of the innovative design a comparison with the traditional solution is undertaken. A vorticity measure based on the integral of the velocity gradient tensor second...
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On various modelling approaches to real-time visualisation of blood flow
PublikacjaThis paper reviews various modelling approaches to real-time visualisation of blood flow. These include classic, macroscale approach based on the momentum conservation equation together with a proper constitutive equation. Moreover, modern micro- and mesoscale approaches, such as molecular dynamics and dissipative particle dynamics, are discussed. Advantages and disadvantages of the discussed methods are highlighted with particular...
Rok 2014
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Investigation of the aerodynamics of an innovative verticalaxis wind turbine
PublikacjaThis paper presents a preliminary three dimensional analysis of the transient aerodynamic phenomena occurring in the innovative modification of classic Savonius wind turbine. An attempt to explain the increased efficiency of the innovative design in comparison with the traditional solution is undertaken. Several vorticity measures such as enstrophy, absolute helicity and the integral of the velocity gradient tensor second invariant...
Rok 2013
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On Invariants of Fluid Mechanics Tensors
PublikacjaThis paper presents physical interpretations of the first and second invariants of tensors of fluid mechanics. Some examples of elementary applications and meanings are also given.
Rok 2012
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GENERALISED HERSCHEL MODEL APPLIED TO BLOOD FLOW MODELLING
PublikacjaThis paper introduces a new rheological model of blood as a certain generalisation of the standard Herschel-Bulkley model. This model is a rheological constitutive equation and belongs to the group of the so-called generalised Newtonian fluids. Experimental data is compared with results, obtained from the new model, to demonstrate that it allows for the best agreement together with Luo-Kuang model. The new model may be easily implemented...
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Numerical prediction of steady and unsteady tip vortex cavitation on hydrofoils
PublikacjaArtykuł przedstawia metodę numeryczną do wyznaczania kawitujących wirów wierzchołkowych powstających za płatami nośnymi. Metoda ta jest oparta na rozwiązywanie dwufazowego turbulentnego przepływu cieczy lepkiej. Pozwala ona wyznaczyć geometrię kawitującego wiru dla różnych geometrii płata nośnego i dla różnych parametrów przepływu. Pokazano porównanie wyników obliczeń z pomiarami i rejestracjami wykonanymi na modelu płata w tunelu...
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Wybrane zagadnienia modelowania przepływów krwi i mikroklimatu w kombinezonach ochronnych
PublikacjaMonografia dotyczy wybranych zagadnień przepływu krwi w naczyniach krwionośnych i przepływów powietrza w tzw. mikroklimacie. Przytoczono równania zachowania opisujące ruch krwi w skali makro wraz z reologicznymi równaniami konstytutywnymi. Poświęcono szczególną uwagę warunkom brzegowym z uwzględnieniem warunków zgodności. Przedstawiono funkcje i cechy krwi, które są istotne przy konstruowaniu równań konstytutywnych, które opisują...
Rok 2011
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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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An Experimental and Numerical Study of Tip Vortex Cavitation
PublikacjaArtykuł przedstawia eksperymentalne i numeryczne badanie kawitujacych wirów wierzchołkowych. Eksperymenty przeprowadzono w tunelu kawitacyjnym na modelu płata nośnego, wykonując pomiary pola prędkości wokół wiru przy pomocy metody Particle Image Velocimetry (PIV). Równolegle przeprowadzono numeryczne symulacje kawitującego wiru wierzchołkowego dla różnych parametrów przepływu. Symulacje wykonano programami Fluent i CFX, stosując...
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Experimental Validation of Numerical Model within a Flow Configuration of the Model Kaplan Turbine
PublikacjaThis paper investigates validation of flow within a model Kaplan turbine. This includes comparison of various turbulence models and their influence on torque and power generated by the turbine. Numerical results were compared with experimental data.
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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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On a Method of Efficiency Increasing in Kaplan Turbine
PublikacjaThis paper presents a method of increasing efficiency in Kaplan-type turbine. The method is based on blade profile optimisation together with modelling the interaction between rotor and stator blades. Loss coefficient was chosen as the optimisation criterion, which is related directly to efficiency. Global optimum was found by means of Genetic Algorithms, and Artificial Neural Networks were utilised for approximations to reduce...
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Variational Method of Finding Streamlines in Ring Cascades for Creeping Flows
PublikacjaThis paper presents a new, analytical method of finding streamlinesfor creeping flows inside a ring cascade which is composed of an infinite number of infinitely thin blades. An analytical solution has been obtained through minimisation of a dissipation functional by means of variational calculus method. The necessary condition for optimum of a functional gives the Stokes equation if some additional assumptions are introduced....
Rok 2010
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1D Model Callibration on the Basis on 3D calculations for Tesla Turbine
PublikacjaThe paper presents the system of equations for axisymmetriclaminar flow, after averaging, through the width of interdisk slit ofTesla turbine. Coefficients were introduced, as a result ofaveraging, that improve the efficiency of 1D model. The minimalnumber of such coefficients was determined. The 1D modelmakes it possible to attain analytical solutions to an accuracylimited by these coefficients. Calibration of 1D model depends...
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On some extensions of Murray's Law
PublikacjaThis paper cites the original Murray's law about optimal radii.Extensions to some class of non-newtonian flows that aredescribedby Ostwalda-de Waele model and newtonian flows foreliptical crosssections. A generalisation of Murray's law formultiobjectiveformulation is also given. It is shown that theoriginal formulation of optimal condition is a particular case ofmultiobjective formulation.
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Rotor Blade Geometry Optimisation in Kaplan Turbine
PublikacjaThe paper presents the description of method and results of rotor blade shape optimisation. The rotor blading constitutes a part ofturbine flow path. Optimisation consists in selection of the shape that minimises ratio of polytrophic loss. Shape of the blade isdefined by the mean camber line and thickness of the airfoil. Thickness is distributed around the camber line based on the ratio ofdistribution. Global optimisation was done...
Rok 2009
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Design optimisation of air-fed full pressurised suits
PublikacjaOpisano szczegóły złożoności zjawisk cieplno-przepływowych pomiędzy wewnętrzną powierzchnią kombinezonu ochronnego i zewnętrznego ubioru. Komplikacja polega na jednoczesnym rozważaniu wymiany masy i ciepła wraz z realistycznymi, trójwymiarowymi geometriami. Dodatkowo rozważany jest ludzki metabolizm. Zrozumienie tych zjawisk i umiejętnośćich symulacji jest konieczna w celu właściwych prac projektowych nad nowymi typami kombinezonów...
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Determining heat transfer coefficients using evolutionary alogrithms
PublikacjaPokazano sposób kalibracji współczynnika wymiany ciepła za pomocą algorytmów ewolucyjnych. Wykorzystano tu minimalizację błędu między pomiarami a obliczeniami. Pokazano dwie metody optymalizacji: wielokryterialną i jednokryterialną.
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Heat and mass transfer in air-fed pressurised suits
PublikacjaOpisano konieczność modelowania transportu masy i ciepła w kombinezonach ochronnych. Omówiono różne sposoby modelowania wymiany ciepła, łącznie ze sprzężoną wymianą ciepła. Uwzględniono również ludzki metabolizm i turbulentne mechanizmy wymiany masy i ciepła. Publikacja opisuje również sposób modelowanie turbulentnych przepływów wieloskładnikowych. Pokazano również porównanie obliczeń z eksperymentem.
Rok 2008
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Heat and mass transfer in air-fed pressurised suits
PublikacjaOpisano konieczność modelowania transportu masy i ciepła w kombinezonach ochronnych. Omówiono różne sposoby modelowania wymiany ciepła, łącznie ze sprzężoną wymianą ciepła. Uwzględniono również ludzki metabolizm i turbulentne mechanizmy wymiany masy i ciepła. Publikacja opisuje również sposób modelowanie turbulentnych przepływów wieloskładnikowych. Pokazano również porównanie obliczeń z eksperymentem.
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Thermo-fluid Transport Phenomena in Air-fed Pressurised Protective Clothing
PublikacjaPublikacja opisuje sposób modelowania turbulentnych przepływów dwuskładnikowych w ciśnieniowych kombinezonach ochronnych, które używane są w reaktorach fuzyjnych. Rozważane są różne modele turbulencji. Przepływy modelowane są w realistycznych geometriach, które odtwarzane są metodą fotogrametrii. Pokazano również sposób modelowania kondensacji pary wodnej na wewnętrznych powierzchniach kombinezonów.
Rok 2005
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Statistical and fractal analysis of human heart dynamics.
PublikacjaPrzedstawiono sposób obliczania podstawowych i bardziej zaawansowanych (dyskrepancja) wielkości statystycznych do analizy dynamiki ludzkiego serca. Oprócz analizy statystycznej pokazano elementy analizy fraktalnej (wykresy Poincare). Przedstawiona analiza umożliwia wykrywanie patologicznych sytuacji i jest pomocna lekarzom w diagnostyce.
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