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Search results for: CLUMPS OF DISCS
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Nanometer structural columns and frustration of magnetic ordering inNb12O29
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Separation of CO2 from biogas using absorption columns
PublicationBiogaz zawiera ok. 50-70% metanu, 30-40% di tlenku węgla oraz niewielkie ilości innych związków jak siarkowodór czy amoniaku. Dla uzyskania wysokokalorycznego gazu konieczne jest usunięcie ze strumienia di tlenku węgla. Praca opisuje potencjał użycia do tego celu kolumn absorpcyjnych oraz cieczy jonowych jako absorbenta
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Torsional Stability Assessment of Columns Using Photometry and FEM
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Corrosion mechanisms in columns for atmospheric distillation of crude oil
PublicationThe paper presents the most common corrosion processes occurring in the columns for atmospheric distillation of crude oil. It describes the mechanisms leading to formation of the chemical compounds, which contribute to corrosion phenomena. The main technological factors influencing corrosion processes have been indicated. The paper also presents the interactions between particular corrosion mechanisms resulting in acceleration...
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Ultrasonic Tomography of Brick Columns Based on FEM Calculations
PublicationUltrasonic tomography is one of the most developed method of non-destructive testing. Despite being used mainly in medicine, it is becoming more and more popular as a method for monitoring of structural elements. It allows to examine the internal structure and technical condition of the tested element. This paper investigates the influence of crosssectional geometry on an obtained tomographic image. Wave propagation signals were...
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Axial capacity of steel built-up battened columns
PublicationThis paper deals with the numerical investigation aimed to study the axial capacity of pin-ended steel built-up columns. Three methods of calculating forces in chords and batten, taking into account the material and geometric imperfections specified in the Eurocode 3 are considered. The aim of this study was to compare different methods allowing the calculation of the column load capacity and determine a simpler and faster method...
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Selected Stability Problems of Thin-Walled Columns and Beams
PublicationThe article reviews a number of papers in the light of buckling analy- sis of thin-walled columns and beams. Stability of thin-walled columns and beams are considered a vital engineering science issue in both historical and present-day approaches. The paper refers to the recent authors’ works of the 2012–2019 period, published in leading journals. Similar review of stability problems of thin-walled structures developed at Gdansk...
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On the paradox of torsional buckling of thin-walled I columns
PublicationAnaliza wyboczenia skrętnego pręta cienkościennego o dwuteowym przekroju poprzecznym ze zmienną, w pewnych granicach, szerokością półek wykazała, że siła krytyczna wyboczenia skrętnego może przekraczać granice wyznaczone przez siły odpowiadające prętom o stałych ekstremalnych szerokościach półek. Ten paradoksalny wynik uzyskano w ramach teorii prętów cienkościennch o przekroju nieodkształcalnym. Ponadto wykazano, że punkt bifurkacji...
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Nanometer structural columns and frustration of magnetic ordering in Nb12O29
PublicationDyskutowana jest synteza i właściwości magnetyczne tlenku niobu Nb12O29. Polimorfizm Nb12O29 przejawia się występowaniem dwóch faz: jednoskośnej i ortorombowej. Pomiar podatności magnetycznej pokazuje, że faza jednoskośna wykazuje antyferromagnetyczne przejście ok. 12K.
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Displacement control in PWK-type pumps
PublicationW referacie zaprezentowano konstrukcję mechanizmu sterowania wydajnością zastosowanego w pompach z rozrządem krzywkowym typu PWK. Przedstawiono wyniki wstępnych badań prototypu PWKZ-78 oraz komputerową analizę zjawisk zachodzących w komorze cylindrowej pompy.
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Displacement control in PWK-type pumps
PublicationThe most important, strategic goal however is creation of the variable displacement version of the new pump PWK. Thanks to full discharge of it's commutation mechanism from hydrostatic forces the variable pump can be directly controlled by low-energy actuator like proportional electromagnet or stepping motor. It means that costly and complicated hydraulic servomechanism (applied in all present variable displacement pumps) is no...
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Selection of drive engines for dredge pumps
PublicationThis paper presents the principles of selecting drive engines for dredge pumps, formulated by this author. In order to formulate them influence of drive engines on dredge pump characteristics and dredger effectiveness, have been analyzed. Also, an analysis of results of the author's operational investigations concerning energy consumption and parameters of excavated soil transport on board dredgers has been performed.
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New generation of the satellite hydraulic pumps
PublicationHydraulic satellite machines are known and produced in many versions, recognizable by the number of humps on their inner rotor and external gear, and therefore by the number of cooperating gears (satellites). All known shapes were however designed on the base of preliminary assumption that rotor’s and external gear’s pitch lines are formed by merging arcs, tangent to each other in the. This assumption makes calculations easier,...
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A Comparison of the Exergy Efficiencies of Various Heat-Integrated Distillation Columns
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Incorporating installation effects into the probability analysis of controlled modulus columns
PublicationThis technical report presents the probabilistic analysis which integrates the Monte Carlo simulation (MCS) with random field theory to model the load–displacement behavior of Controlled Modulus Columns (CMCs) in overconsolidated Poznań clay. Presented study focuses on the practical aspects of statistical analysis of geotechnical data, numerical model development, and results evaluation. Variability and spatial distribution of...
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Buckling of thin-walled columns accounting for initial geometrical imperfections
PublicationThe paper is devoted to the effect of some geometrical imperfections on the critical buckling load of axially compressed thin-walled I-columns. The analytical formulas for the critical torsional and flexural buckling loads accounting for the initial curvature of the column axis or the twist angle respectively are derived. The classical assumptions of theory of thin-walled beams with non-deformable cross-sections are adopted. The...
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Effect of initial imperfection on buckling of thin-walled I columns
PublicationEffects of initial geometrical imperfections on critical buckling loads of thin-walled I columns are investigated. Torsional and flexural buckling are taken into account. The column behaviour is described in accord to the theory of thin-walled beams with nondeformable cross-section. Some numerical examples and conclusions related to effects of imperfections on properties of the critical loads are presented.
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The experimental research on RC columns, loaded at sign-variable eccentricity
PublicationThe research focuses on testing the behaviour of the reinforced concrete columns compressed at a variable eccentricity. The fact of possible variable eccentricity in compressed columns is not considered in the current calculation procedures. The objective of the research was to examine whether indeed the load history has no impact and whether the reinforced concrete columns compressed at eccentric of variable sign could be analysed...
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Flexural buckling and post-buckling of columns made of aluminium alloy
PublicationThe paper concerns flexural buckling and initial post-buckling of axially compressed columns made of aluminium alloy described by the Ramberg-Osgood relationship. The non-linear differential equation of the problem is derived using the stationary total energy principle and the assumptions of classical beam theory within a finite range. The approximate analytical solution of the equation leading to the buckling loads and initial...
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Investigation of natural frequencies of axially loaded thin-walled columns
PublicationThe paper deals with correlation between natural frequencies of two steel thin-walled columns and the corresponding applied load. The structures are made of cold-formed lipped channel sections. The columns lengths were assumed to follow two buckling patterns – global flexural and flexural-torsional buckling. In the thicker structure two material models were considered – linearly-elastic and elastic-perfectly plastic. Numerical...
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Sensitivity analysis of flexural and torsional buckling loads of laminated columns
PublicationThe paper concerns first order sensitivity analysis of flexural and torsional bucklin g loads of axiallycompressed thin-walled columns with bisymmetric or axisymmetric cross-section made of unidirectional fibre-reinforcedlaminate. The first variation of critical loads versus some variations of the column material properties and cross-sectionaldimensions is derived. Numerical examples dealing with simply supported I-columns are...
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Torsional buckling and post-buckling of columns made of aluminium alloy
PublicationThe paper concerns torsional buckling and the initial post-buckling of axially compressed thin-walled aluminium alloy columns with bisymmetrical cross-section. It is assumed that the column material behaviour is described by the Ramberg–Osgood constitutive equation in non-linear elastic range. The stationary total energy principle is used to derive the governing non-linear differential equation. An approximate solution of the equation...
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Strengthening of thin-walled columns against flexuralbuckling at elevated temperatur.
PublicationZa pomocą analizy wrażliwości wyznaczono mmiejsca wzmocnienia słupa stalowego obciążonego działaniem wysokiej temperatury. Wyznaczono przybliżoną wartość siły krytycznej słupa przy zmiennej temperaturze. Zastosowano model stali zgodny z polską normą PN-90/B-03200.
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Stability analyses of a cylindrical steel silo with corrugated sheets and columns
PublicationW artykule przedstawiono wyniki obliczeń stateczności silosów z blachy falistej ze słupami. Wykonano analizy linowe i analizy nieliniowe stosując metody elementów skończonych. W obliczeniach uwzględniono model przestrzenny powłokowy oraz uproszczony model przestrzenny z blachy ortotropowej z belkami. Wyniki numeryczne porównano z Eurokodem.
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Diagnostics of commutation unit in satellite pumps and motors
PublicationThe article describes a part of the research on the development of satellite pumps and motors, conducted on Gdansk University of Technology as a part of grant "New elaborate of hydraulic satellite machines for drives with vegetable liquids and non-flammable liquids" (LIDER/35/102/L-2/10/NCBiR/2011) funded by the National Centre for Research and Development in Poland. The presented area includes the diagnostics of commutation units...
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Diagnostics of commutation unit in satellite pumps and motors
PublicationThe article describes a part of the research on the development of satellite pumps and motors, conducted on Gdansk University of Technology as a part of grant "New elaborate of hydraulic satellite machines for drives with vegetable liquids and non-flammable liquids" (LIDER/35/102/L-2/10/NCBiR/2011) funded by the National Centre for Research and Development in Poland. The presented area includes the diagnostics of commutation units...
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Axial piston pumps with camdriven commutation unit
PublicationPrzedstawiono wyniki badań prototypów pomp wielotłoczkowych osiowych wyposażonych w rozrząd krzywkowy oraz ich porównanie z rezultatami osiąganymi przez produkowane obecnie jednostki z rozrządem czołowym. Podano dane techniczne pomp nowego typu wchodzących do produkcji.
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Hygienic design of pumps, homogenisers and dampening devices.
PublicationPrzedstawiono wymagania dotyczące materiałów oraz ich przygotowania, a także dla powierzchni wewnętrznych i zewnętrznych urządzeń takich jak pompy, homogenizatory i nawilżacze oraz ich elementów, zwłaszcza wielu typów uszczelnień, ze względu na ich zastosowanie do produkcji żywności w warunkach sanitarno-higienicznych i maksymalne wyeliminowanie zagożeń dla jakości podczas jej wytwarzania w różnorodnych procesach technologicznych.
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Two dimensional inverse solution for diagonal pumps
PublicationW pracy przedstawiono rozwiązanie zadania odwrotnego dla wirnika i kierownicy pompy diagonalnej. Dla założonego kształtu powierzchni prądu wyznaczono kształt łopatek obu palisad. Geometria kanałów łopatkowych została wyznaczona w wyniku rozwiązania układu równań zapisanych w krzywoliniowym układzie współrzędnych. W pracy przedstawiono fotografie wirnika wykonanego techniką Rapid Prototyping.
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On some aspects of torsional buckling of thin-walled I-beam columns
PublicationW pracy podsumowano wyniki badań zjawiska wyboczenia skrętnego prętów o przekroju dwuteowym. Zbadano wpływ początkowego wygięcia giętnego na wartość siły krytycznej wyboczenia skrętnego. Z zasady stacjonarności energii potencjalnej wyprowadzono równania różniczkowe wyboczenia skrętnego. Wartość siły krytycznej wyznaczono stosując podejście perturbacyjne. Wyniki analityczne porównano z rezultatami otrzymanymi za pomocą 6-parametrowej...
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Modeling of chromatographic lipophilicity of food synthetic dyes estimated on different columns
PublicationBadano parametry retencyjne wybranych syntetycznych barwników żywności z wykorzystaniem techniki RP-HPLC z wykorzystaniem kolumn z chemicznie modyfikowanym wypełnieniem typu C-8, C-16, C-18 oraz CN.Uzyskane wyniki mogą być podstawą do stwierdzenia, że badane związki charakteryzują się podobnymi parametrami retencyjnymi w stosunku do kolumn z fazą stacjonarną typu C-8, C-16 oraz C-18.
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The use of GFRP tubes as load-bearing jackets in concrete-composite columns
PublicationThe paper presents the fields of applications of polymer composites in building structures. The use of composite glass fibre tubes is discussed in more detail. The laboratory methods used to test the mechanical properties of these pipes are presented. An original research program is presented, including six concrete-filled glass fibre tubes. The cylinders and columns made in this way were tested for their axial load capacity. Conclusions...
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Numerical analysis on axial capacity of steel built-up battened columns
PublicationThis paper deals with the numerical analysis aimed at study the bearing capacity of pinended steel built-up columns under axial compression. Finite element (FE) models were performed for the columns presented in the literature. The main problem discussed in the article is the shape and magnitude of geometric imperfections introduced into the numerical FE model, necessary to obtain the load capacity consistent with the experimental...
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Direct design of Controlled Modulus Columns (CMC) based on in-situ testing
PublicationIn this paper, the serviceability limit state and bearing capacity of tension screw displacement piles were analyzed using the results of static pile load tests, carried out on the test plot near the Elbląg city, and field, and laboratory tests. The paper presents the methodology of determining the pile load-settlement curve using different types of t-z transfer functions. The new method of constructing the pile load-settlement...
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Distortional buckling of thin-walled columns of closed quadratic cross-section
PublicationThe elastic stability of axially compressed column related to the cross-section distortion is investigated. Two kinds of closed quadratic cross-sections are taken into consideration with internal walls and without it. The governing differential equation is derived with aid of the principle of stationary total potential energy. The critical loads for the simply supported columns are found in an analytical form and compared with...
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COMPUTER-AIDED CONSTRUCTION AT DESIGNING REINFORCED CONCRETE COLUMNS AS PER EC
PublicationThe article presents the author’s computer program for designing and dimensioning columns in reinforced concrete structures taking into account phenomena affecting their behaviour and information referring to design as per EC. The computer program was developed with the use of C++ programming language. The program guides the user through particular dimensioning stages: from introducing basic data such as dimensions, concrete...
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Computer analysis of dynamic phenomena in PWK-type pumps
PublicationReferat przedstawia wstępne wyniki analizy CFD dynamicznych zmian ciśnienia zachodzących w komorze cylindrowej pompy z rozrządem krzywkowym PWKZ-95. Analizy prowadzono dla pompy wyposażonej w elastyczną komorę kompensacyjną oraz dla pompy bez kompensacji.
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Compensation of pressure peaks in pwk-type hydraulic pumps
Publicationhydraulic axial pumps equipped with cam-driven commutation unit (pwk pumps) proved their high efficiency up to 55 mpa and ability to work self-sucking, even at high speed. displacement of pwk pump may easily be changed by moving its control cam. full discharge from hydrostatic forces makes such control possible by direct action of a low-energy actuator like proportional electromagnet or stepping motor. that eliminates heavy and...
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HIGH TEMPERATURE HEAT PUMPS – PERSPECTIVE HEATING SYSTEMS?
PublicationIn the paper presented are authors own concepts of high temperature compressor heat pumps for the utilisation of medium and low temperature sources of heat. Working fluids for use in high temperature heat pumps are discussed, as well as the criteria for their selection. Analyses are presented for the production of in the upper steam source at 130 °C. One-stage systems and cascade systems were analyzed. An analysis of the coefficient...
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Determination of pharmaceutical residues in drinking water in Poland using a new SPE-GC-MS(SIM) method based on Speedisk extraction disks and DIMETRIS derivatization
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World Pumps
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Selected problems of stability of thin-walled columns with bisymmetric open cross-section
PublicationPraca dotyczy problemów stateczności osiowo ściskanych prętów o bisymetrycznym przekroju otwartym. Badano wpływ nieliniowości materiału pręta oraz wstępnego zakrzywienia osi na wyboczenie skrętne oraz początkową ścieżkę pokrytyczną. Na przykładach numerycznych wykazano, że w pewnych przypadkach stateczny, symetryczny punkt może zmienić się na symetryczny ale niestateczny, co oznacza możliwość redukcji siły krytycznej.
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Sensitivity analysis of buckling loads of bisymmetric I-section columns with bracing elements
PublicationWyznaczono pierwsza wariacje siły krytycznej wyboczenia słupa o przekroju bisymetrycznym otwartym przy wariacji sztywnosci i połozenia stezen. Przyjeto załozenia klasycznej teorii pretów cienkosciennych o nieodkształcalnym przekroju poprzecznym. Analizowano zarówno stezenia boczne jak i stezenia ograniczajacespaczenie oraz skrecenie przekroju poprzecznego. Stezenia modelowano jako podpory sprezyste. W przykładzie numerycznym zbadano...
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Experimental study on steel columns subjected to impact load under earthquake conditions
PublicationEarthquakes affecting urbanized regions cause exceptional loads to load bearing structural elements such as columns. Such a boost in the load conditions can lead to severe damages which, in a worst case scenario, can lead to a total collapse of a building. This boost is caused by the horizontal ground movement generating a rise in the internal forces due to considerable large displacement between the top and bottom support of columns....
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Simplified stability analysis of steel cylindrical silos with corrugated walls and vertical columns
PublicationIn the paper a simplified stability analysis of steel cylindrical silos composed of corru¬gated walls and vertical open-sectional columns was proposed. The whole 3D silo was modeled as a single column resting on elastic foundation provided by the silo walls. In proposed formula for the calculation of the foundation stiffness the curvature of the silo walls was taken into account. Three different analyses were carried out using...
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Investigation of buckling resistance of columns using non-linear static and dynamic analysis
PublicationThe aim of this paper is to investigate the stability process in an axially compressed column using a static and dynamic finite element analysis by taking both the geometric and material non-linearity into account. The perfect column and column with geometric imperfections were analysed. The linear buckling analyses were used to obtain the lowest buckling load and shapes of buckled forms that were taken into account as initial...
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Using different types of capillary columns as denudation traps: a comparision of sorption properties
PublicationOpisano badania odcinków kapilarnych kolumn chromatograficznych (WCOT, SCOT,PLOT) jako pułapek denudacyjnych do ilościowego zatrzymywania śladowych ilości lotnych związków organicznych ze strumienia powietrza. W trakcie badań modelowych (z wykorzystaniem gazowych mieszanin wzorcowych) określono wartości współczynników podziału benzenu, toluenu, etylobenzenu, o-ksylenu i chlorobenzenu (Kfs). Stwierdzono, że grubość filmu fazy stacjonarnej...
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FE-analysis of failure behaviour of reinforced concrete columns under eccentric compression
PublicationArtykuł omawia obliczanie słupów żelbetowych poddanych ściskaniu mimośrodowemu z uwzględnieniem lokalizacji odkształceń. Obliczenia wykonano przy zastosowaniu MES i sprężysto-plastycznego prawa konstytutywnego rozszerzonego o długość charakterystyczną mikrostruktury za pomocą teorii nielokalnej.
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The usfulness of the SLUMS test for diagnosis of mild cognitive impairment and dementia
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Axial piston pumps with cam driven commutation unit. z.
PublicationPrzedstawiono wyniki badań i podstawowe dane techniczne typowego szeregu pomp wielotłoczkowych osiowych wdrażanych do produkcji seryjnej.