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Search results for: FORCED WAVES
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Modeling of Passive and Forced Convection Heat Transfer in Channels with Rib Turbulators
PublicationThe main goal of the research presented in this paper was the experimental and numerical analysis of heat enhancement and aerodynamic phenomena during air flow in a channel equipped with flow turbulators in the form of properly configured ribs. The use of ribs intensifies the heat transfer and at the same time increases not only the flow resistance but also the energy costs. Therefore, designing modern heat exchangers with optimal...
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CENTRAL-FORCE DECOMPOSITION OF THE TERSOFF POTENTIAL
PublicationCentral forces play important role in the analysis of results obtained with particle simulation methods, since they allow evaluating stress fields. In this work we derive expressions for a central-force decompositon of the Tersoff potential, which is often used to describe interatomic interactions in covalently bonded materials. We simplify the obtained expressions and discuss their properties.
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3D calculations of aerodynamic forces causing self-excited vibrations of turbine rotor systems. Part II: Pressure forces
PublicationPrzedstawiono wyniki badań numerycznych sił generowanych w uszczelnieniu nadbandażowym stopnia turbinowego przeprowadzone metodą Fluent. Uwzględniono niecentryczne położenie osi wirnika względem osi korpusu. Rozpatrzono bandaże o różnej geometrii. Niektóre wyniki zweryfikowano doświadczalnie.
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Electromagnetic forced vibrations of composite nanoplates using nonlocal strain gradient theory
PublicationThis article is intended to analyze forced vibrations of a piezoelectric-piezomagnetic ceramic nanoplate by a new refined shear deformation plate theory in conjunction with higher-order nonlocal strain gradient theory. As both stress nonlocality and strain gradient size-dependent effects are taken into account using the higher-order nonlocal strain gradient theory, the governing equations of the composite nanoplate are formulated....
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Experimental Investigations of Forced Convection of Nanofluids in Smooth, Horizontal, Round Tubes: A Review
PublicationA comprehensive review of published works dealing with experimental studies of forced convection heat transfer of nanofluids is presented. The survey is limited to straight, smooth, and round tubes. Moreover, only mono nanofluids exhibiting Newtonian behaviour are considered. Works on experimental research of forced convection in tubes are presented in a chronological order in the first part of the article. In this part, attention...
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Homoclinic orbits for an almost periodically forced singular Newtonian system in R^3
Publication. This work uses a variational approach to establish the existence of at least two homoclinic solutions for a family of singular Newtonian systems in R^3 which are subjected to almost periodic forcing in time variable
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Experimental investigation of forced convection of water-Al2O3 nanofluids inside horizontal tubes,
PublicationIn this paper, forced convection of water–Al2O3 nanofluids inside horizontal copper tube is studied experimentally. Experiments were conducted for three, i.e. 0.1%, 1% and 5% nanoparticle mass concentrations under transition and turbulent flow regimes. Average heat transfer coefficients and pressure drop values were determined and compared to distilled water. Enhancement of heat transfer for lower nanoparticle concentration and...
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Experimental investigation of forced convection of water/EGAl2O3 nanofluids inside horizontal tube
PublicationIn 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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Impact of Temperature and Nanoparticle Concentration on Turbulent Forced Convective Heat Transfer of Nanofluids
PublicationTheoretical analysis of the influence of nanoparticles and temperature on the average Nusselt (Nu) number and the average heat transfer coefficient (HTC) during the turbulent flow of nanofluid in a horizontal, round tube was carried out. The Nu number is a function of the Reynolds (Re) number and the Prandtl (Pr) number, which in turn are functions of the thermophysical properties of the liquid and the flow conditions. On the other...
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Tests for lapping of flat surfaces of ceramic elements with forced dosing of abrasive slurry
PublicationPrzedstawiono zagadnienia dotyczące systemu wymuszonego dawkowania zawiesiny ściernej w docieraniu jednotarczowym powierzchni płaskich. Opisano zalety takiego systemu dozowania płynnej zawiesiny ściernej. Omówiono wybrane wyniki badań docierania elementów z ceramiki technicznej. Analizowano wpływ podstawowych warunków dawkowania zawiesiny na ubytek liniowy próbek.
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Surface finite viscoelasticity and surface anti-plane waves
PublicationWe introduce the surface viscoelasticity under finite deformations. The theory is straightforward generalization of the Gurtin–Murdoch model to materials with fading memory. Surface viscoelasticity may reflect some surface related creep/stress relaxation phenomena observed at small scales. Discussed model could also describe thin inelastic coatings or thin interfacial layers. The constitutive equations for surface stresses are...
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Numerical investigations of the nonlinear waves generation in a bubble layer
PublicationRozważano zagadnienie propagacji fal różnych częstotliwości wewnątrz warstwy z pęcherzykami. Przedstawiono model matematyczny zjawiska oraz wyniki badań teoretycznych. Badano zmiany widma fali bieżącej i odbitej jak również zmiany amplitud wybranych harmonicznych ciśnienia tych fal w funkcji grubości warstwy i koncentracji pęcherzyków.
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Floe-size distributions in laboratory ice broken by waves
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Floe-size distributions in laboratory ice broken by waves
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Floe-size distributions in laboratory ice broken by waves
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Floe-size distributions in laboratory ice broken by waves
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A note on the vertical distribution of momentum transport in water waves
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Application of RMS for damage detection by guided elastic waves
PublicationThis paper presents certain results of an experimental study related with a damage detection in structural elements based on deviations in guided elastic wave propagation patterns.
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Modeling of the acoustic waves propagation in non-homogeneous medium
PublicationRozważano zagadnienie propagacji fal w ośrodku niejednorodnym. Przedstawiono model matematyczny i przykładowe wyniki badań numerycznych. Model matematyczny zbudowano w oparciu o równanie KZK. Do rozwiązania zagadnienia zastosowano metodę różnic skończonych. Badano zmiany ciśnienia i zmiany widma odpowiednio w ośrodku jednorodnym i niejednorodnym.
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Strongly anisotropic surface elasticity and antiplane surface waves
PublicationWithin the new model of surface elasticity, the propagation of anti-plane surface waves is discussed. For the proposed model, the surface strain energy depends on surface stretching and on changing of curvature along a preferred direction. From the continuum mechanics point of view, the model describes finite deformations of an elastic solid with an elastic membrane attached on its boundary reinforced by a family of aligned elastic...
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Tollmien- Shlichting and sound waves interaction: nonlinear resonances.
PublicationRozpatruje się oddziaływanie różnych typów modów hydrodynamicznych w warstwie lepkiej. Stwierdzono możliwość istnienia oddziaływania rezonansowego.Dokładne równania ewolucyjne kierujące dynamiką warstwy lepkiej zostały wypisane.
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Nonlinear waves in optical waveguides and soliton theory applications
PublicationRównania teorii solitonów zastosowano do propagacji impulsów światła w falo-wodach dielektrycznych.Wyprowadzono i zbadano rozwiazania równań oddziaływa-nia (z uwzględnieniem tłumienia) trzech fal Maxwella-Blocha.
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Propagation of elestic waves in beams including damping effects.
PublicationW pracy przedstawiono wyniki analizy propagacji fali sprężystej w belce z tłumieniem wiskotycznym.
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Ingoing and outgoing waves in the non-relativistic theory of photoionization
PublicationZastosowano rachunek zaburzeń zależny od czasu do wyprowadzenia wzoru na różniczkowy przekrój czynny na fotojonizację nierelatywistycznego kwantowego układu jednoelektronowego płaską monochromatyczną falą elektromagnetyczną. Pokazano,że pochodzenie oraz asymptotykę tzw. ''funkcji falowej stanu końcowego'', wchodzącej do tego wzoru, można wytłumaczyć bez odwoływania się do kontrowersyjnej argumentacji podanej przez Breita i Bethego.
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Methods of determining cutting forces during woodcutting
PublicationW artykule przedstawiono podstawowe metody określania sił przy przecinaniu drewna, które ulegały modyfikacjom wraz z postępem wynikającym z badań nad tym procesem. Przedstawione metody podzielono na dwie grupy: podejście klasyczne oraz nowatorskie podejście z zastosowaniem mechaniki pękania, które uwzględniają różne własności mające wpływ na proces przecinania. Podejście klasyczne reprezentują metody opierające się na właściwym...
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Isomerization and Decomposition of 2-Methylfuran with External Forces
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Reduction of pressure forces in turbine labyrinth seals
PublicationPrzedstawiono nową metodę zmniejszani sił samowzbudnych typu aerodynamicznego. zastosowano ją do różnych typów nadbandażowych uszczelnień labiryntowych. Efektywność rdukcji sił samowzbudnych wynosiła nawet ponad 60%. Potwierdzone rezultay obliczeniami i eksperymentalnie.
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Buckling analysis of cold formed steel column
PublicationW pracy przedstawiono analizę słupa zimnogiętego o przekroju otwartym. Przeprowadzono analizy statyczne liniowe i nieliniowe. Analizowano wpływ podłoża sprężystego oraz sztywność połączenia dwóch sąsiednich słupów.
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DEFORMATIONS OF INNOVATIVE COLD-FORMED GEB SECTIONS
PublicationPermanent urban growth of the world of today world implies demanding challenges for the steel construction industry. Nowadays, one of the most important issues is the cost optimization of steel structures. Since the weight of building materials is a major component of the total cost, engineers and designers try to reduce structural weight, without compromising durability and sustainability of a steel structure. Therefore, light...
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Buckling Analysis of Cold Formed Silo Column
PublicationThe paper is devoted to stability analysis of different models of steel cold formed silo column. The steel cylindrical silos are often composed of corrugated walls and vertical open-sectional columns uniformly placed along the silo circumference. Both the whole 3D silo, a simplified model consisting of one column with a part of the silo walls, and a single column resting on elastic foundation provided by the silo walls were analyzed....
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Stability of an Innovative Cold-Formed GEB Section
PublicationThis paper is focused on the numerical analysis and experimental test of stability of the cold-formed profile with an innovative GEB cross-section. For the shell model of the axially compressed member, the linear buckling analysis and the nonlinear static analysis were carried out. In the numerical research, the buckling load and the limit load for variable section heights were obtained. Some of the results were compared with the...
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On local buckling of cold-formed channel members
PublicationThe paper deals with local buckling of the compressed flanges of cold-formed thin-walled channel beams subjected to pure bending or axially compressed columns. Arbitrarily shaped flanges of open cross-sections and the web-flange interactions are taken into account. Buckling deformation of a beam flange is described by displacement related to torsion of the flange about the line of its connection with the web. Total potential energy...
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Manoeuvring forces on azimuthing podded propulsor model
PublicationThis 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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Influence of the shoe type on the ground reaction forces
PublicationThe aim of this work was to estimate a relationship between the type of the footwear and ground reactions. Differences in medio-lateral, anterior-posterior and vertical reactions are compared for different shoe-types for male and female volunteers. Each of the participants gait was recorded in case of different shoes and without them, also stabilograms were analyzed. Results revealed differences in ground reaction forces for different...
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On hydrodynamic forces acting on the ship in large motions.
PublicationPraca zapoznaje czytelnika ze współczesnym stanem dynamiki statku w nieliniowym ujęciu, ukierunkowanym na unikanie zbyt daleko idących komplikacji w rozwiązaniu. Nieliniowość dotyczy przede wszystkim sił Fronda-Kryłowa oraz sił tłumienia po wejściu pokładu do wody, czy też oporu stępek przechyłowych. Do pozostałych sił towarzyszących i dyfrakcyjnych stosuje się ekstrapolację podejścia liniowego.
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Extension of the Force Matching Method to Anisotropic Coarse-Grained Transferable Force Fields: Application to the Unres Model of Proteins
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Medical Journal Armed Forces India
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Pakistan Armed Forces Medical Journal
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The influence of rotor-stator axial gap on the aerodynamic forces generatedin the shroud clearance of a turbine stage. Part II: Forces and moments
PublicationPrzedstawiono wyniki badań doświadczalnych wpływu zmiany luzu osiowego na wymuszenia aerodynamiczne powstające w uszczelnieniu nadbandażowym stopnia powietrznej turbiny modelowej. Wykazano, że w przypadku uszczelnienia promieniowego zmiana luzu osiowego odgrywa niewielką rolę w generowaniu sił i momentów aerodynamicznych w szczelinie nadbandażowej w porównaniu ze zmianą mimośrodowości czy skośnego ustawienia osi wirnika względem...
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Determination of stepped plate thickness distribution using guided waves and compressed sensing approach
PublicationGuided waves recently have attracted significant interest as a very promising research area. The signals registered by a specially designed sensor network are processed to assess the state of the tested structure. Despite the constant development of novel damage detection algorithms employing guided waves, the phenomenon of wave propagation still needs detailed recognizing and understanding for the further progress of non-destructive...
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Simulations of wave propagation and attenuation in fields of colliding ice floes
Open Research DataThis dataset contains results of numerical smulations of sea ice-wave interactions, corresponding to laboratory experiments conducted at the Large Ice Model Basin (LIMB) at the Hamburg Ship Model Basin (HSVA) as part of the LS-WICE ("Loads on Structure and Waves in Ice"; https://zenodo.org/record/1067170#.XrLt_dhpxhE) project. THe simulations were conducted...
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Forced degradation studies of ivabradine and in silico toxicology predictions for its new designated impurities
PublicationAll activities should aim to eliminate genotoxic impurities and/or protect the API againstdegradation. There is a necessity to monitor impurities from all classification groups,hence ivabradine forced degradation studies were performed. Ivabradine was provedto be quite durable active substance, but still new and with insufficient stability data.Increased temperature, acid, base, oxidation reagents and...
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Multistage Coupling of Eight Mistuned Bladed Disk on a Solid Shaft, Forced Vibration Analysis
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Forced Degradation Studies of Ivabradine and In Silico Toxicology Predictions for Its New Designated Impurities
PublicationAll activities should aim to eliminate genotoxic impurities and/or protect the API against degradation. There is a necessity to monitor impurities from all classification groups, hence ivabradine forced degradation studies were performed. Ivabradine was proved to be quite durable active substance, but still new and with insufficient stability data. Increased temperature, acid, base, oxidation reagents and light were found to cause...
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Nonlinear Free and Forced Vibrations of a Hyperelastic Micro/Nanobeam Considering Strain Stiffening Effect
PublicationIn recent years, the static and dynamic response of micro/nanobeams made of hyperelasticity materials received great attention. In the majority of studies in this area, the strain-stiffing effect that plays a major role in many hyperelastic materials has not been investigated deeply. Moreover, the influence of the size effect and large rotation for such a beam that is important for the large deformation was not addressed. This...
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Homoclinics for singular strong force Lagrangian systems
PublicationWe study the existence of homoclinic solutions for a class of generalized Lagrangian systems in the plane, with a C1-smooth potential with a single well of infinite depth at a point ξ and a unique strict global maximum 0 at the origin.Under a strong force condition around the singular point ξ, via minimization of an action integral, we will prove the existence of at least two geometrically distinct homoclinic solutions.
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A Maximum-Likelihood Approach to Force-Field Calibration
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GUIDED WAVES IN SHIP STRUCTURAL HEALTH MONITORING – A FEASIBILITY STUDY
PublicationShips and offshore structures operate in a severe corrosion degradation environment and face difficulty in providing long- lasting corrosion protection. The Classification Societies recommend regular thickness measurements leading to structural component replacements, to ensure structural integrity during service life. The measurements are usually performed using ultrasonic thickness gauges and such an approach requires multiple...
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Pressure distribution for different types of the finite amplitude waves sources
PublicationPrzedstawiono model matematyczny i przykładowe wyniki badań numerycznych zjawiska oddziaływań fal o skończonej amplitudzie w wodzie. Model matematyczny zbudowano w oparciu o równanie KZK. Zagadnienie różniczkowe rozwiązano stosując metodę różnic skończonych. Rozważono różne rozkłady ciśnienia na źródle kołowym i bez osiowej symetrii.
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Application of guided waves in the evaluation of steel-concrete adhesive connection
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