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Search results for: FREE BOUNDARY PROBLEM
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Experimental and comparative study on the two-phase pressure drop of air-water mixture in U-bend and straight pipe annuli
PublicationIn this paper, the experimental and theoretical analysis of pressure drop in singlephase and two phase-flow were presented for straight and U-bend smooth tube annulus and tube annulus with wire coil insert. Experiments for various boundary conditions were performed. In case of U-tube and straight tube with and without turbulator, tests were made for the water-water and air-water systems. The study covered a wide measuring range,...
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Analytical Steady-State Model of the Pipeline Flow Process
PublicationThe paper addresses the issue of modeling the flow process in transmission pipelines. A base model used for numerical simulation is introduced. Under certain assumptions concerning steady state analysis, the differential equations describing the process are solved analytically for two cases: zero and nonzero inclination angle α. These equations describe a constant flow rate and a corresponding distribution of the pressure along...
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Optimized Hydrodynamic Vortex Separator
PublicationThe invention discloses an optimized hydrodynamic vortex separator which comprises an outer cylinder (1), an inner cylinder (2), a sludge hopper (3), an inlet (4), an outlet (5) and a conical structure (7), wherein the outer cylinder (1) is the boundary of the outer wall of the separator; wherein the inner cylinder (2) is arranged in an inner cavity of the outer cylinder (1); the sludge hopper (3)is taken as the bottom of the...
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Flexomagneticity in buckled shear deformable hard-magnetic soft structures
PublicationThis research work performs the first time exploring and addressing the flexomagnetic property in a shear deformable piezomagnetic structure. The strain gradient reveals flexomagneticity in a magnetization phenomenon of structures regardless of their atomic lattice is symmetrical or asymmetrical. It is assumed that a synchronous converse magnetization couples both piezomagnetic and flexomagnetic features into the material structure....
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Thermal buckling of functionally graded piezomagnetic micro- and nanobeams presenting the flexomagnetic effect
PublicationGalerkin weighted residual method (GWRM) is applied and implemented to address the axial stability and bifurcation point of a functionally graded piezomagnetic structure containing flexomagneticity in a thermal environment. The continuum specimen involves an exponential mass distributed in a heterogeneous media with a constant square cross section. The physical neutral plane is investigated to postulate functionally graded material...
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Selected problems of decision making modelling in power engineering
PublicationThe paper presents the selected problems of decision making modelling in power engineering specially investment risk evaluation methods. The proposed model can be used in the range programming the development and investing process in power engineering. Decision making problems in power engineering and the evaluation of investment effectiveness in particular are closely related to modelling which relatively accurately reflects...
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Free-air anomaly grid on the Gulf of Gdańsk
Open Research DataWe present an attempt to determine the accuracy of shipborne gravimetry for the needs of geoid determination. The shipborne gravity campaign, is the beginning of a series of gravimetry measurements in the Polish Exclusive Economy Zone. The campaign was conducted in the area where the accuracy of geoid determination is crucial for the safety of navigation...
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The complexity of the L(p,q)-labeling problem for bipartite planar graphs of small degree
PublicationW pracy pokazano, że problem L(p,q)-kolorowania przy użyciu ''t'' kolorów jest NP-zupełny nawet w wersji ograniczonej do grafów planarnych dwudzielnych małego stopnia, nawet dla stosunkowo niewielkich wartości ''t''. Jako wniosek z uzyskanych wyników stwierdzono, że problem L(2,1)-kolorowania grafów planarnych przy użyciu 4 kolorów jest NP-zupełny, a także że problem L(p,q)-kolorowania grafów o maksymalnym stopniu 4 jest NP-zupełny...
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Nonlinear free and forced vibrations of a dielectric elastomer-based microcantilever for atomic force microscopy
PublicationThe majority of atomic force microcode (AFM) probes work based on piezoelectric actuation. However, some undesirable phenomena such as creep and hysteresis may appear in the piezoelectric actuators that limit their applications. This paper proposes a novel AFM probe based on dielectric elastomer actuators (DEAs). The DE is modeled via the use of a hyperelastic Cosserat model. Size effects and geometric nonlinearity are included...
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ENGINEERING ANALYSIS WITH BOUNDARY ELEMENTS
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Między konsumpcjonizmem a ascetyzmem ekologicznym: problem ekologicznej jakości ekologicznego stylu życia.
PublicationW pracy podjęty jest problem ekologicznej redefinicji pojęcia ''jakość życia''. Jako drogą poszukiwań wskazuje się orientację na kształtowanie nowego paradygmatu socjo-ekonomicznego i nowego socjokulturowego wzorca potrzeb budowanego na nowych, proekologicznych motywacjach.
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Joanna Raczek dr inż.
PeopleEmployment 2003 -- 2019: Faculty of Applied Physics and Mathematics, Gdańsk University of Technology. 2019 - present: Faculty of Electronic, Informatics and Telecominications, Gdańsk University of Technology. Education May 2007: Doctor of Philosophy in Mathematics, University of Gdańsk. Doctoral dissertation: "Paired domination and doubly domination in graphs". Supervisor: dr hab. Jerzy Topp. 2000 -- 2004 Bachelor of Science...
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Offshore surface waters of Antarctica are free of microplastics, as revealed by a circum-Antarctic study
PublicationIn 2018, during a circum navigation of Antarctica below 62° S by the sailing boat Katharsis II, the presence of plastics was investigated with surface sampling nets at ten evenly spaced locations (every 36° of longitude). Although fibres that appeared to be plastic (particles up to 2 cm) were found in numbers ranging from 1 particle (0.002 particles per m3) to 171 particles (1.366 particles per m3) per station, a Fourier-transform...
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Quasilinear elliptic problem in anisotropic Orlicz–Sobolev space on unbounded domain
PublicationWe study a quasilinear elliptic problem $-\text{div} (\nabla \Phi(\nabla u))+V(x)N'(u)=f(u)$ with anisotropic convex function $\Phi$ on the whole $\R^n$. To prove existence of a nontrivial weak solution we use the mountain pass theorem for a functional defined on anisotropic Orlicz-Sobolev space $\WLPhispace(\R^n)$. As the domain is unbounded we need to use Lions type lemma formulated for Young functions. Our assumptions broaden...
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Free vibration of truncated-cone columns
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POLFEL - Free Electron Laser in Poland
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Survivability analysis of scale-free networks
PublicationPraca dotyczy aspektów złośliwej kompromitacji stacji sieciowych poprzez epidemie wirusów komputerowych oraz ataki hackerskie. Opisano nowy autorski model analizy przeżywalności atakowanych sieci bezskalowych i ocenę metod zabezpieczeń. Pokazano wyniki modelowania efektywności środków powstrzymujących epidemie wirusów, polityk filtracji w ścianach ogniowych, efektywności blokowania adresów. Wszystkie wyniki są oryginalne i publikowane...
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Covariance approach to the free photon field
PublicationWprowadziliśmy teorię fotonu poprzez tą samą zasadę, co dla pojedynczej czą-stki w kwantowej mechanice używając C*-algebraicznego podejścia kowariantychukładów.
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Short-range order structure and free volume distribution in liquid bismuth: X-ray diffraction and computer simulations studies
PublicationThe structure of liquid bismuth was studied by X-ray diffraction and computer simulation methods. The contraction of the atomic structure within the first coordination sphere in the temperature interval of 575- 1225 K is reported. The temperature dependencies of the coordination numbers and of the free volume are analysed. On the basis of the temperature dependencies of the free volume, the temperature dependencies of viscosity...
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Dziennikarz jako specjalista public relations - problem tożsamości czy nadużycie etyczne?
PublicationArtykuł analizuje często występujące w Polsce zjawisko łączenia zawodu dziennikarza i specjalisty public relations. Czyni to rozpatrując problem z p punktu widzenia etyki dziennikarskiej, rzetelności pracy specjalisty public relations i opinii publicznej, jej prawa do rzetelnej informacji.
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THE PROBLEM OF THE CALCULATION OF THE FREQUENCY OF DIAGNOSTIC EXAMINATIONS BASED ON DEVICE’S PROPER OPERATION TIME
PublicationThe paper presents the proposal to apply the normal distribution to solve the problem of the frequency of diagnostic tests. Particular emphasis is placed on simplicity of the method. This method may be useful for the average user technical system. The method reduces the number of assumptions to a minimum. The results do not raise of serious doubts but they require verification of course.
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Grafo-mania, czyli rzecz o grafach i algorytmach. Problem 8 hetmanów
PublicationW eseju spojrzano na problem 8 hetmanów na szachownicy z punktu widzenia teorii grafów
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Experimental Investigation of Free Convection Heat Transfer from Horizontal Cylinder to Nanofluids
PublicationThe results of free convection heat transfer investigation from a horizontal, uniformly heated tube immersed in a nanofluid are presented. Experiments were performed with five base fluids, i.e., ethylene glycol (EG), distilled water (W) and the mixtures of EG and water with the ratios of 60/40, 50/50, 40/60 by volume, so the Rayleigh (Ra) number range was 3 104 Ra 1.3 106 and the Prandtl (Pr) number varied from 4.4 to 176....
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Problem reakcji krzyżowych w immunodiagnostyce na przykładzie neosporozy i toksoplazmozy
PublicationW niniejszej pracy przedstawiono problem reakcji krzyżowych występujących w immunodiagnostyce chorób zakaźnych. Zagadnienie opisano szerzej na przykładzie dwóch blisko spokrewnionych pasożytów należących do typu Apicomplexa - Neospora caninum i Toxoplasma gondii. Zaprezentowano także, sposoby ulepszania testów wykorzystywanych w diagnostyce neosporozy i toksoplazmozy u zwierząt.
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Solving the Problem of Dynamic Adaptability of Artificial Intelligence Systems that Control Dynamic Technical Objects
PublicationThis paper investigates the increase in the response speed and stability of artificial intelligence systems that control dynamic technical objects. The problem of calculating the optimal time of switching an artificial intelligence system between software classes by the criterion of the rigidity degree of the model of a control object is considered. The solution of this problem is proposed for the general case of the control object...
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Adenosine triphosphate in the marine boundary layer in the southern Baltic Sea
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Modelling of Edge Insulation Depending on Boundary Conditions for the Ground Level
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Four-point boundary-value problems for differential-algebraic systems
PublicationBadane są czteropunktowe problemy brzegowe dla układów równań różniczkowo-algebraicznych. Stosując metodę iteracji monotonicznych, podano warunki dostateczne na istnienie rozwiązań (jednego lub ekstremalnych) takich problemów. Podano przykład ilustrujacy otrzymane wyniki teoretyczne.
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Quadratic approximation of solutions for differential equations with nonlinear boundary conditions.
PublicationZastosowano metodę kwazilinearyzacji i sformułowano warunki dostateczne przy których iteracje monotoniczne są kwadratowo zbieżne do jedynego rozwiązania wymienionego w tytule zagadnienia różniczkowego. Uzyskane wyniki uogólniają niektóre wcześniej publikowane rezultaty gdy warunek brzegowy był liniowy.
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Waveform relaxation and comparison methods for multistep boundary value problems
PublicationStosując metody o których mowa w tytule pracy, podano warunki dostateczne na istnienie i jednoznaczność rozwiązania układów równań różniczkowo-funkcyjnych z warunkami brzegowymi. Pokazano zbieżność tych metod do rozwiązania problemu. Otrzymane wyniki zilustrowano przykładami.
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Ordinary differential equations with nonlinear boundary conditions of antiperiodic type.
PublicationZastosowano metodę kwazilinearyzacji do równań różniczkowych zwyczajnych z nieliniowymi warunkami brzegowymi typu antyokresowego. Podano warunki dostateczne przy których iteracje monotoniczne są zbieżne do jedynego rozwiązania naszego problemu i jest to zbieżność kwadratowa. Iteracje te są rozwiązaniami odpowiednich równań liniowych z liniowymi warunkami brzegowymi.
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Linear boundary problems for ordinary differential equations with deviated arguments
PublicationPraca dotyczy istnienia i jednoznaczności rozwiązań dla problemów brzegowych w tym również i problemów z wielopunktowymi warunkami brzegowymi.
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Extensions of Quasilinearization Method for Differential Equations with Integral Boundary Conditions
PublicationPraca dotyczy równań różniczkowych z warunkami brzegowymi typu całkowego. Podano warunki dostateczne na istnienie jedynego rozwiązania takiego zagadnienia i pokazano, że odpowiednio konstruowane ciągi monotoniczne są zbieżne do tego rozwiązania i jest to zbieżność kwadratowa. Te monotoniczne ciągi są przybliżonymi rozwiązaniami problemu wyjściowego i obustronnie szacują szukane rozwiązanie.
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Effect of boundary conditions in shear testers on properties of bulk solids.
PublicationPrzedstawiono wpływ warunków brzegowych w dwóch różnych aparatach ścinania na wielkość odkształceń i naprężeń. Obliczenia wykonano przy zastosowaniu metody elementów skończonych i mikropolarnego prawa hipoplastycznego.
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Multiple sound sources localization in free field using acoustic vector sensor
PublicationMethod and preliminary results of multiple sound sources localization in free field using the acoustic vector sensor were presented in this study. Direction of arrival (DOA) for considered source was determined based on sound intensity method supported by Fourier analysis. Obtained spectrum components for considered signal allowed to determine the DOA value for the particular frequency independently. The accuracy of the developed...
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Measurements and Visualization of Sound Intensity Around the Human Head in Free Field Using Acoustic Vector Sensor
PublicationThis paper presents measurements and visualization of sound intensity around the human head simulator in a free field. A Cartesian robot, applied for precise positioning of the acoustic vector sensor, was used to measure sound intensity. Measurements were performed in a free field using a head and torso simulator and the setup consisting of four different loudspeaker configurations. The acoustic vector sensor was positioned around...
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Equivalent Single Layer Models in Free Vibration Analysis of Laminated Multi-Layered Plates
PublicationThe performance of selected equivalent single-layer (ESL) models is evaluated within several classical benchmark tests for small amplitude free vibration analysis of multi-layered plates. The authors elaborated their own Finite Element software based on the first-order shear deformation (FOSD) theory with some modifications incorporated including a correction of the transverse shear stiffness and an application of zigzag type functions....
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A FPTAS for minimizing total completion time in a single machine time-dependent scheduling problem
PublicationIn this paper a single machine time-dependent scheduling problem with total completion time criterion is considered. There are given n jobs J1,…,Jn and the processing time pi of the ith job is given by pi=a+bisi, where si is the starting time of the ith job (i=1,…,n),bi is its deterioration rate and a is the common base processing time. If all jobs have deterioration rates different and not smaller than a certain constant u>0,...
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Trailing-Edge Separation Control of a NACA 0015 Airfoil Using Dielectric-Barrier-Discharge Plasma Actuators
PublicationThis paper presents a part of the works conducted in the Plasmaero European project (task 3.1), where the trailing-edge flow separation of a NACA 0015 airfoil has been controlled using four different dielectric barrier discharge (DBD) actuator types at three institutions across Europe. The results show that it is possible to enhance the aerodynamic performance of aircraft at speeds up to 40 m/s. Dielectric-barrier-discharge vortex...
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COMPARISON OF HEAT TRANSFER CHARACTERISTICS IN SURFACE COOLING WITH BOILING MICROJETS OF WATER, ETHANOL AND HFE7100
PublicationThe basis of microjet technology is to produce laminar jets which when impinging the surface have a very high kinetic energy at the stagnation point. Boundary layer is not formed in those conditions, while the area of film cooling has a very high turbulence resulting from a very high heat transfer coefficient. Applied technology of jet production can result with the size of jets ranging from 20 to 500μm in breadth and 20 to 100μm...
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Investigations On Water Circulation in Animal Sea-Water Basins – On the Example of Seals′ Breeding Pools
PublicationThis paper presents general comments concerning investigations on water circulation in animal breeding pools containing sea water. As an example are given results of computer simulation of water circulation in seals’ breeding pools situated in Marine Station at Hel, belonging to Oceanographic Institute, Gdansk University. A mathematical model of three main pools was prepared with taking into account their inflow and outflow water...
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Surface sliding in human abdominal wall numerical models: Comparison of single-surface and multi-surface composites
PublicationDetermining mechanical properties of abdominal soft tissues requires a coupled experimental-numerical study, but first an appropriate numerical model needs to be built. Precise modeling of human abdominal wall mechanics is difficult because of its complicated multi-layer composition and large variation between specimens. There are several approaches concerning simplification of numerical models, but it is unclear how far one could...
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Modular Approach for Modelling Warming Up Process in Water Installations with Flow-Regulating Elements
PublicationThe paper presents a new method for modelling the warming up process of a water system with elements regulating the flow in a stochastic manner. The paper presents the basic equations describing the work of typical elements which the water installation is composed of. In the proposed method, a new computational algorithm was used in the form of an iterative procedure enabling the use of boundary conditions that can be stochastically...
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A study on diagnosing both isotropic and orthotropic, intentionally damaged laminates
PublicationBeing the most detrimental mode in laminated structures, delamination initially degrades local structural strength, and lastly causes global structural failure, thus necessitating delamination identification at its incipient stages. For identification purposes, a comprehensive numerical and experimental study on delamination within both the laminated isotropic acrylic-glass and orthotropic epoxyglass plates is presented. As the...
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Influence of addition of carbon nanotubes on rheological properties of selected liquid lubricants - a computer simulation study
PublicationThis work is motivated by the improvement of anti-friction properties of lubricants by addition of CNTs proved experimentally in literature. In particular, a methodology is developed to compute the shear viscosity of liquid lubricants (Propylene Glycol) based on Molecular Dynamics simulation. Non-Equilibrium molecular dynamics (NEMD) approach is used with a reactive force field ReaxFF implemented in LAMMPS. The simulations are...
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Persistences: analysis of the image of Gdańsk and its cultural identity through survey processes and digital architectural representation
PublicationThe aim of the research was to analyse the historical legacy/heritage of the city of Gdańsk in order to characterise the narrative tools which can be used to promote the cultural identity of the urban landscape. The main focus was on the city's defence system - a cultural route that is spatially limited to a relatively small area, but temporally spanning almost a millennium. The fortifications demarcate a spatial boundary, limiting...
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Effect of Ion and Binding Site on the Conformation of Chosen Glycosaminoglycans at the Albumin Surface
PublicationAlbumin is one of the major components of synovial fluid. Due to its negative surface charge, it plays an essential role in many physiological processes, including the ability to form molecular complexes. In addition, glycosaminoglycans such as hyaluronic acid and chondroitin sulfate are crucial components of synovial fluid involved in the boundary lubrication regime. This study presents the influence of Na+, Mg2+ and Ca2+ ions...
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Dynamic modeling of non-cylindrical curved viscoelastic single-walled carbon nanotubes based on the second gradient theory
PublicationThis paper is devoted to the theoretical study of the dynamic response of non-cylindrical curved viscoelastic single-walled carbon nanotubes (SWCNTs). The curved nanotubes are largely used in many engineering applications, but it is challenging in understanding mechanically the dynamic response of these curved SWCNTs when considering the influences of the material viscosity. The viscoelastic damping effect on the dynamic response...
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Study on the Coastline Evolution in Sopot (2008–2018) Based on Landsat Satellite Imagery
PublicationThe coastline is the boundary between the water surface in a reservoir or watercourse and the land, which is characterised by high instability and functional diversity. For these reasons, research on coastal monitoring has been conducted for several decades. Currently, satellite images performed with synthetic aperture radars (SARs) are used to determine its course and variability together with high-resolution multispectral imagery...
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Electrochemical performance of thin free-standing boron-doped diamond nanosheet electrodes
PublicationIn the following work we describe preparation and the electrochemical performance of thin and free-standing heavy boron-doped diamond (BDD) nanosheets. The investigated foils were deposited on Ta substrate using microwave plasma-enhanced chemical vapor deposition technique (MPECVD). Foils of two B-dopant densities were investigated, obtained on the base of 10 k and 20 k ppm [B]/[C] ratio in the gas admixture. The obtained foils...