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Wyniki wyszukiwania dla: DIFFERENCE-IN-DIFFERENCES
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Evolution of chemotaxis in single-cell artificial organisms
PublikacjaThe model of a liquid two-dimensional environment, which is based on physics of diffusion, allows us to simulate the diffusion of morphogenes. Artificial organisms move using a chemotaxis reacting to concentration difference. Organisms are controlled by a gene regulatory network coded in a linear genome and reproduce by division. We made a lot of experiments presenting organisms’ behaviour in various environment conditions. We...
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Water uptake analysis of acceptor-doped lanthanum orthoniobates
PublikacjaIn this work, lanthanum orthoniobates doped with either antimony, calcium, or both have been synthesized and studied. The water uptake of the investigated materials has been analyzed by means of thermogravimetric studies. The results show the difference between the thermodynamics of hydration between the lanthanum orthoniobate system and other proton conducting ceramics. The relation between the water uptake and effective acceptor...
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Analysis of Floodplain Inundation Using 2D Nonlinear Diffusive Wave Equation Solved with Splitting Technique
PublikacjaIn the paper a solution of two-dimensional (2D) nonlinear diffusive wave equation in a partially dry and wet domain is considered. The splitting technique which allows to reduce 2D problem into the sequence of one-dimensional (1D) problems is applied. The obtained 1D equations with regard to x and y are spatially discretized using the modified finite element method with the linear shape functions. The applied modification referring...
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A high-accuracy method of computation of x-ray waves propagation through an optical system consisting of many lenses
PublikacjaThe propagation of X-ray waves through an optical system consisting of many X-ray refractive lenses is considered. Two differential equations are contemplated for solving the problem for electromagnetic wave propagation: first – an equation for the electric field, second – an equation derived for a complex phase of an electric field. Both equations are solved by the use of a finite-difference method. The simulation error is estimated...
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Coherent-wave Monte Carlo method for simulating light propagation in tissue
PublikacjaSimulating propagation and scattering of coherent light in turbid media, such as biological tissues, is a complex problem. Numerical methods for solving Helmholtz or wave equation (e.g. finite-difference or finite-element methods) require large amount of computer memory and long computation time. This makes them impractical for simulating laser beam propagation into deep layers of tissue. Other group of methods, based on radiative...
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Detecting coupling directions with transcript mutual information: A comparative study
PublikacjaCausal relationships are important to understand the dynamics of coupled processes and, moreover, to influence or control the effects by acting on the causes. Among the different approaches to determine cause-effect relationships and, in particular, coupling directions in interacting random or deterministic processes, we focus in this paper on information-theoretic measures. So, we study in the theoretical part the difference between...
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ASYNCHRONICZNY MULTILATERACYJNY SYSTEM DOZOROWANIA OBSZAROWEGO
PublikacjaW artykule przedstawiono nową metodę lokalizowania samolotów w multilateracyjnych systemach dozorowania obszarowego WAM (Wide Area Multilateration). Metoda ta, nazwana AWAM (Asynchronous Wide Area Multilateration), umożliwia estymację położenia samolotu bez znajomości różnicy w rytmie pracy RTD (Relative Time Difference) pomiędzy stacjami naziemnymi (sensorami). Metoda AWAM znacząco upraszcza proces lokalizowania samolotów w rzeczywistych...
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Excitation of the Secondary Modes by the Broad Spectrum Sound in a Liquid with Relaxation Losses
PublikacjaFeatures of nonlinear phenomena and, in particular, acoustic excitation of the entropy and relaxation modes in a liquid electrolyte with a chemical reaction are examined. The total range of frequencies of an exciter is considered, and the instantaneous dynamic equations are derived which govern perturbations in the secondary modes. The instantaneous leading-order acoustic forces of the secondary modes are evaluated. Examples of harmonic...
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Resonance Frequency Calculation of Spherical Microstrip Structure Using Hybrid Technique
PublikacjaIn this paper the spherical microstrip structure is considered. The structure is composed of a metallic patch with an arbitrary shape placed on a dielectric coated metallic sphere. In the analysis the hybrid technique is utilized. In this approach the finite-difference technique is applied in a cavity model to determine the current basis functions on the patch. Next, using method of moments, the resonance frequency of the structure...
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Labyrynths generators, their properties and practical application in computer games
Publikacjathis paper presents three basic algorithms for generation of mazes, and many of their modifications and examples showing their practical application in creating random structures that resembles those from the real world. the paper highlights the difference in the labyrinths classes generated by listed algorithms and describes a specific and highly likely to occur shapes that occur in generated mazes. particular attention was paid...
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Towards an efficient multi-stage Riemann solver for nuclear physics simulations
PublikacjaRelativistic numerical hydrodynamics is an important tool in high energy nuclear science. However, such simulations are extremely demanding in terms of computing power. This paper focuses on improving the speed of solving the Riemann problem with the MUSTA-FORCE algorithm by employing the CUDA parallel programming model. We also propose a new approach to 3D finite difference algorithms, which employ a GPU that uses surface memory....
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On the convergence of a finite-difference discretization à la Mickens of the generalized Burgers–Huxley equation
PublikacjaIn this note, we establish the property of convergence for a finite-difference discretization of a diffusive partial differential equation with generalized Burgers convective law and generalized Hodgkin–Huxley reaction. The numerical method was previously investigated in the literature and, amongst other features of interest, it is a fast and nonlinear technique that is capable of preserving positivity, boundedness and monotonicity....
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Numerical FDM modelling of wave propagation in concrete structure
PublikacjaThe article presents application of finite difference method to damage detection and its size evaluation in concrete structure by elastic wave propagation method. The simulations of wave propagation in concrete structure were performed for six different damage scenarios. Damages were modelled as areas with changed material properties. Investigation focused on the influence of damage size on the energy of wave reflection. Presented...
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Silent Sonar with matched filtration
PublikacjaRadars with continuous wave frequency (CW FM sonars) are used in radiolocation as 'silent sonars'. They determine the distance to target by measuring the difference between the frequency of the sounding signal and echo signal. The article presents the principle of operation and parameters of silent CW FM sonars. Target distance determined by these sonars is based on the signal at the output of the matched filter. The Doppler effect...
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ZEUS Concept and Its Wider European Application
PublikacjaThe objectives of the ZEUS project and the resulting concept of an integrated system of transport safety are recapitulated in the article. The context for transport safety management that has evolved since this became a concern of the European Union under the Treaty of Union in 1993 is outlined, and some issues related to applying the ZEUS concept across Europe are discussed. It is concluded that there is scope for exploring ways...
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Filtracja danych TDOA w filtrze UKF w systemie multilateracyjnym
PublikacjaW artykule przedstawiono implementację metody filtracji danych pomiarowych w systemie MLAT(Multilateration), która ma na celu zwiększenie dokładności estymacji położenia poruszającego się statku powietrznego poprzez kompensację błędów pomiarowych. Opisano sposób implementacji algorytmu bezśladowego filtru Kalmana dla danych pomiarowych TDOA (Time Difference of Arrival), a następnie na podstawie zarejestrowanych rzeczywistych tras...
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Estymacja położenia węzłów ruchomych w sieci UWB synchronizowanej emisją z węzła nieruchomego
PublikacjaW referacie przedstawiono wyniki testów możliwości wykorzystania modemów IR UWB (Impulse Radio Ultra-Wide Band) typu DWM1000 do budowy sieci radiolokalizacyjnej, w której położenie węzłów ruchomych jest estymowane na podstawie pomiarów różnic odległości metodą TDOA (Time Difference of Arrival). Opisana została struktura sieci i sposób synchronizacji pomiarów czasów w nieruchomych węzłach referencyjnych przez cykliczny odbiór sygnałów...
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The Economic Legacy of Mega Sporting Events. The Impact of Hosting European Olympic Games on GDP Growth Through Infrastructure Development
PublikacjaIntroduction. The positive legacy of the Olympics is often cited by the International Olympic Committee and national or-ganizers. Some scholars, however, question an uncritical approach to an exclusively positive economic legacy. The aim of this study is to evaluate the impact of hosting the Olympics on infrastructure development, with a potential impact on economic growth in the form of Gross Domestic Product (GDP) in three phases...
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Identification of Parameters Influencing the Accuracy of the Solution of the Nonlinear Muskingum Equation
PublikacjaTwo nonlinear versions of the Muskingum equation are considered. The difference between both equations relates to the exponent parameter. In the first version, commonly used in hydrology, this parameter is considered as free, while in the second version, it takes a value resulting from the kinematic wave theory. Consequently, the first version of the equation is dimensionally inconsistent, whereas the proposed second one is consistent. It...
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Simulation of unsteady flow over floodplain using the diffusive wave equation and the modified finite element method
PublikacjaWe consider solution of 2D nonlinear diffusive wave equation in a domain temporarily covered by a layer of water. A modified finite element method with triangular elements and linear shape functions is used for spatial discretization. The proposed modification refers to the procedure of spatial integration and leads to a more general algorithm involving a weighting parameter. The standard finite element method and the finite difference...
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High-Resolution, Broad-Range Detection Setup for Polarimetric Optical Fiber Sensors
PublikacjaA common-path polarization interferometer using a Wollaston prism and an area detector for the measurement of retardation or optical path difference is presented. Employing a moderate-resolution 1280 by 1024 pixel monochrome camera, it offers a measurement range of approximately 780 radians at 830 nm and 1350 radians at 515 nm while maintaining a high measurement resolution. Retardation introduced by a zero-order waveplate or a...
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Experimental analysis of the behaviour of different types of joints in the steel structure model subjected to earthquake loading
PublikacjaThe present paper reports the results of the experimental study performed to investigate the behaviour of two different types of joints (destroyed and welded ones) in the model of the steel structure under seismic excitations. The structure was subjected to three earthquakes, namely Kobe, Loma Prieta and Northridge, using the shaking table investigation. The results obtained from the study...
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Modal analysis of a fish-belly flap type of steel water gate
PublikacjaABSTRACT: The results of a modal analysis of the fish-belly flap type of steel water gate are presented in the paper. The analysis was conducted for a detailed numerical model of the structure using four-node quadrilateral shell elements. The study was focused on the examination of the influence of positioning of the flap gate and hydrostatic pressure of water on the eigenvalues and eigenmodes of the structure. The results of the study...
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Numerical Analysis of Steady Gradually Varied Flow in Open Channel Networks with Hydraulic Structures
PublikacjaIn this paper, a method for numerical analysis of steady gradually varied fl ow in channel networks with hydraulic structures is considered. For this purpose, a boundary problem for the system of ordinary differential equations consisting of energy equation and mass conservation equations is formulated. The boundary problem is solved using fi nite difference technique which leads to the system of non-linear algebraic equations....
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Magnetic field microsensor based on GaAs MESFET
PublikacjaA novel concept of the drain separation design in a horizontally-split-drain GaAs MAGFET sensor, based on epitaxial layer growth, was developed. Proper choice of GaAs/AlAs/GaAs epitaxial layer sequence provided good electrical isolation between the drain regions. The measured leakage current between the drain regions was in the range of nA for up to 2V drain voltage bias difference. Performed analytical and numerical calculations...
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Method of lines for Hamilton-Jacobi functional differential equations.
PublikacjaInitial boundary value problems for nonlinear first order partial functional differential equations are transformed by discretization in space variables into systems of ordinary functional differential equations. A method of quasi linearization is adopted. Suffcient conditions for the convergence of the method of lines and error estimates for approximate solutions are presented. The proof of the stability of the diffrential difference...
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A New Expression for the 3-D Dyadic FDTD-Compatible Green's Function Based on Multidimensional Z-Transform
PublikacjaIn this letter, a new analytic expression for the time-domain discrete Green's function (DGF) is derived for the 3-D finite-difference time-domain (FDTD) grid. The derivation employs the multidimensional Z-transform and the impulse response of the discretized scalar wave equation (i.e., scalar DGF). The derived DGF expression involves elementary functions only and requires the implementation of a single function in the multiple-precision...
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Impact of radio wave polarisation on off-body communications in indoor environments
PublikacjaThis paper describes the measurements and the analysis of the impact of radio wave polarisation on off-body communications in Body Area Networks in indoor environments. Measurements on polarisation impact are briefly described. Five investigated scenarios with different body postures and different antenna placements are characterised. The difference between the vertical and horizontal components of the received radio signal are...
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Feature Weighted Attention-Bidirectional Long Short Term Memory Model for Change Detection in Remote Sensing Images
PublikacjaIn remote sensing images, change detection (CD) is required in many applications, such as: resource management, urban expansion research, land management, and disaster assessment. Various deep learning-based methods were applied to satellite image analysis for change detection, yet many of them have limitations, including the overfitting problem. This research proposes the Feature Weighted Attention (FWA) in Bidirectional Long...
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The influence of combination of binding agents on fatigue properties of deep cold in-place recycled mixtures in Indirect Tensile Fatigue Test (ITFT)
PublikacjaThe publication presents fatigue properties of cold recycled mixtures for eight combinations of binding agents (cement and bituminous emulsion). Cold recycled mixtures were evaluated in Indirect Tensile Fatigue Test (ITFT) at the temperature of 20 C in controlled stress mode. As a function of horizontal stress, fatigue life is strongly influenced by combination of the binding agents. When fatigue life is analyzed as a function...
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Dynamic analysis of lightweight structure of the Viaduct Millau in France subjected to the wind fluctuations described by Karman’s and Davenport’s spectrum
PublikacjaThe article presents numerical simulations for wind impact modelling on the Millau Viaduct structure in France performed with two independent spectrum generation methods. The viaduct's construction in affected by strong forces, as it is situated in the Tarn river's valley. Thus, the loading coming from the wind cannot be modelled, the way it is in case of simple structures as static loading, but as a loading in a form of a spectrum...
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Approximate solution for Euler equations of stratified water via numerical solution of coupled KdV system
PublikacjaWe consider Euler equations with stratified background state that is valid for internal water waves. The solution of the initial-boundary problem for Boussinesq approximation in the waveguide mode is presented in terms of the stream function. The orthogonal eigenfunctions describe a vertical shape of the internal wave modes and satisfy a Sturm-Liouville problem. The horizontal profile is defined by a coupled KdV system which is...
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The accuracy of pulse rate estimation from the sequence of face images
PublikacjaThe goal of this paper is to analyze the accuracy of pulse rate estimation from the sequence of face images. Simulated and real signals were used to evaluate two pulse rate estimators; one for frequency domain and the second one for time domain using the autocorrelation function. The results show that the mean difference between the reference measurements and estimated pulse rate values are about 2bpm. In the analysis of short...
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Numerical simulation of hardening of concrete plate
PublikacjaThe paper presents a theoretical formulation of concrete curing in order to predict temperature evolution and strength development. The model of heat flow is based on a well-known Fourier equation. The numerical solution is implemented by means of the Finite Difference Method. In order to verify the model, the in situ temperature measurements at the top plate of a road bridge were carried out. A high agreement between numerical...
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GPU based implementation of Temperature-Vegetation Dryness Index for AVHRR3 Satellite Data
PublikacjaPaper presents an implementation of TVDI (Temperature-Vegetation-Dryness Index) algorithm on GPU (Graphics Processing Unit). Calculation of this index is based on LST (Land Surface Temperature) and NDVI (Normalized Difference Vegetation Index). Discussed results are based on multi-spectral imagery retrieved from AVHRR3 sensors for area of Poland. All phases of TVDI implementation on GPU are modified in respect to CUDA platform....
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Improvement of time difference of arrival measurements resolution by using fractional delay filters in a direct sequence-code division multiple access radionavigation system
PublikacjaThis study presents a method of improving time measurements resolution in a direct sequence-code division multiple access receiver by using a fine code tracking loop based on fractional delay filtering of a despreading sequence. It briefly describes the structure of a generic digital code tracking loop and the proposed modification which allows to measure time difference of arrival values with the subsample resolution, together...
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ASYNCHRONICZNA METODA TDOA
PublikacjaPrzedstawiono nową metodę lokalizowania terminali ruchomych MT (Mobile Terminal) w sieciach radiowych, w których stacje bazowe BS (Base Station) pracują asynchronicznie względem siebie. Metoda ta, nazwana ATDOA (Asynchronous Time Difference of Arrival), umożliwia estymację położenia MT na podstawie pomiarów różnicy czasów propagacji sygnałów radiowych pomiędzy terminalem ruchomym będącym w ruchu, a pojedynczą stacją bazową w różnych...
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GPR simulations for diagnostics of a reinforced concrete beam
PublikacjaThe most popular technique for modelling of an electromagnetic field, the finite difference time domain (FDTD) method, has recently become a popular technique as an interpretation tool for ground penetrating radar (GPR) measurements. The aim of this study is to detect the size and the position of damage in a reinforced concrete beam using GPR maps. Numerical simulations were carried out using the finite differ-ence time domain...
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Image simulation and annotation for color blinded
PublikacjaIn this paper methods for image simulation as seen by a color blinded and a method for constructing images of perceived color difference are presented. The work is also focused on the interactive color description of an image contents. As a result, the individuals having problems with color discrimination can identify colors in an image.W artykule prezentowane są metody symulacji kolorów w obrazach postrzeganych przez osoby ze...
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Performance of a new commercial high-definition 3D patient specific quality assurance system for CyberKnife robotic radiotherapy and radiosurgery
PublikacjaConventional two dimensional and low-definition measurement techniques for dosimetric verification of radiotherapy treatment deliveries are no longer adequate in the era of hypofractionation and extremely high dose gradients. New quality assurance (QA) tools with 3D capability and high definition are urgently needed. The purpose of this study was to evaluate the performance of one of the first such commercial systems as applied...
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An effective method for studying intermolecular interactions in binary liquids with hydrogen bonds: FTIR spectra and ab initio calculations in the N-methylformamide - methanol system
PublikacjaMolecular complexes in methanol (MeOH)−N-methylformamide (NMF) mixtures were studied based on their FTIR-ATR spectra, to which two methods of analysis were applied: factor analysis and a quantitative version of the difference-spectra method. The mean composition of a complex between NMF and MeOH molecules over the whole range of mixture compositions was determined. Absorbing species differentiated with regard to the interaction...
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Comparative analysis of numerical with optical soliton solutions of stochastic Gross–Pitaevskii equation in dispersive media
PublikacjaThis article deals with the stochastic Gross–Pitaevskii equation (SGPE) perturbed with multiplicative time noise. The numerical solutions of the governing model are carried out with the proposed stochastic non-standard finite difference (SNSFD) scheme. The stability of the scheme is proved by using the Von-Neumann criteria and the consistency is shown in the mean square sense. To seek exact solutions, we applied the Sardar subequation...
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COMPUTER ANALYSIS OF HYDRAULIC CONDITIONS IN A SANITARY CHAMBER
PublikacjaThis paper presents analysis of hydraulic conditions of sewage flow down the slipway (ramp) in the collecting sanitary chamber connecting 3 collectors on the inlet: ⌀600, ⌀800 and ⌀1400 and one on the outlet ⌀1600 mm, with a maximum difference of elevation 5 m. The mathematical model has been made and hydraulic calculations were carried out in steady flow conditions. Then wastewater surface elevation, energy grade line elevation,...
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Analiza efektywności metod estymacji położenia terminala ruchomego w środowisku propagacji wielodrogowej
PublikacjaW referacie została zaprezentowana analiza efektywności metod estymacji położenia terminala ruchomego w systemie WCDMA/FDD (Wideband Code Division Multiple Access / Frequency Division Duplex) w warunkach propagacji wielodrogowej. Analizie poddano cztery, najczęściej spotykane w literaturze przedmiotu, metody: Chan'a, Foy'a, Fang'a oraz Friedlander'a. Metody te umożliwiają wyznaczanie położenia geograficznego termi-nala ruchomego...
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Efektywne metody lokalizowania terminala ruchomego w systemie WCDMA/FDD
PublikacjaZaproponowano, poddano analizie i zbadano na drodze symulacyjnej dwie nowe, efektywne metody lokalizowania terminala ruchomego w systemie WCDMA/FDD (Wideband Code Division Multiple Access/Frequency Division Duplex). Metody te umożliwiają estymację położenia terminala ruchomego bez konieczności znajomości różnicy czasów w synchronizacji stacji bazowych RTD (Relative Time Difference). Eliminacja różnicy czasów RTD znacząco upraszcza...
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Lax-Wendroff and McCormack Schemes for Numerical Simulation of Unsteady Gradually and Rapidly Varied Open Channel Flow
PublikacjaTwo explicit schemes of the finite difference method are presented and analyzed in the paper. The applicability of the Lax-Wendroff and McCormack schemes for modeling unsteady rapidly and gradually varied open channel flow is investigated. For simulation of the transcritical flow the original and improved McCormack scheme is used. The schemes are used for numerical solution of one dimensional Saint-Venant equations describing free...
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T1 RELAXATION TIME CALLIBRATION IN MAGNETIC RESONANCE IMAGING USING NANODIAMOND PHANTOMS
PublikacjaMRI is increasingly used in radiation treatment planning because of the excellent soft tissue contrast in the obtained images. It allows more precise definition of the boundaries between healthy tissues and those affected by cancerous lesions. To obtain good image quality, the difference in signal between two types of tissue must be significant despite the noise so it must be properly calibrated. This calibration includes...
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Implementation of TVDI calculation for coastal zone
PublikacjaPaper will show an implementation of TVDI (Temperature-Vegetation-Dryness Index) algorithm on GPU (Graphics Processing Unit). Calculation of this index is based on LST (Land Surface Temperature) and NDVI (Normalized Difference Vegetation Index). Discussed results are based on multi-spectral imagery retrieved from AVHRR3 sensors for area of Poland, especially from region of Gdańsk coastal zone. All phases of TVDI implementation...
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Methods of determination of C coefficient for period of rolling vessel in calm water for example of pax cargo ship
PublikacjaThis article presents a different approach to calculate the C coefficient needed to determine the period of own rolling vessel in calm water. The C coefficient is usually adopted as the approximate value from the available literature, usually depending on the type of vessel, and less dependent on the loading condition. In experimental studies of marine properties (seakeeping) often have a problem with the selection of the correct...
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Determination of the uncertainty of mass flow measurement using the orifice for different values of the Reynolds number
PublikacjaStandard orifice flowmeters are widely used in the chemical and energy industry. Therefore, it is essential to know how accurate the measurements made with these instruments are. The paper presents an estimation of measurement uncertainty of a liquid mass flow using the orifice plate. The authors will present the influence of ranges of the Reynolds number on the estimated uncertainty, obtained on the basis of simulation and laboratory...