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    Wyświetlanie 1-10 z 10
    Tytuł:
    Studies on velocity fields around the cavitation vortices generated by the model of a rotating blade
    Autorzy:
    Suchecki, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/259200.pdf
    Data publikacji:
    2018
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    experimental techniques
    PIV
    cavitation
    rotary hydraulic machinery
    Opis:
    The elimination of hazards caused by cavitation phenomena is an important issue to be considered in the design of process equipment including flow machinery. These hazards are: cavitation erosion, efficiency decrease as well as vibration and noise. One of the most intensive and dangerous forms of cavitation is vortex cavitation that accompanies the operation of hydraulic machines in which components comprised of rotating blades are applied. Velocity fields around cavitation vortices generated by the model of a propeller blade were experimentally studied in a cavitation tunnel. Flow images were recorded using a high-speed camera and processed using particle image velocimetry (PIV) complemented with computer-aided techniques that had been developed for the purpose of this research. These techniques included the removal of image distortions on the basis of a calibration mask, determination of instantaneous velocity distributions and removal of air-bubble traces from flow images. Experimental studies result examples were presented in the form of velocity fields determined in the longitudinal plane as well as in three transverse planes remote from the blade. Instabilities of the cavitating vortex stream and of the local liquid-flow velocity in its surrounding were detected. The effect of the angle of attack of propeller blade on the instability of the vortex stream and the effect of the presence of the cavitating vortex kernel on the local velocities of the surrounding liquid, were determined.
    Źródło:
    Polish Maritime Research; 2018, 2; 66-70
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A method for the accurate numerical prediction of the tip vortices shed from hydrofoils
    Autorzy:
    Flaszyński, P.
    Szantyr, J. A.
    Dymarski, P.
    Kraskowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/259231.pdf
    Data publikacji:
    2010
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    marine propulsors
    vortex generation
    numerical methods
    experimental techniques
    Opis:
    The possibly accurate numerical prediction of the detailed structure of vortices shed from the tips of hydrofoils is an important element of the design process of marine propellers. The concentrated tip vortices are responsible for the propeller cavitation erosion and acoustic emission. The purpose of the project described in this paper was to develop the numerical method for prediction of the tip vortex structure. In the course of the project the numerical calculations were confronted with the results of experimental measurements. This led to creation of the specific method of construction of the computational grid and to selection of the optimum turbulence model. As a result the reliable method for the accurate numerical prediction of the concentrated tip vortices for different hydrofoil geometry and flow conditions has been developed and validated. This method enables elimination of the unfavourable phenomena related to the tip vortices in the course of the propeller design calculations.
    Źródło:
    Polish Maritime Research; 2010, 2; 10-17
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An experimental and numerical study of the vortices generated by hydrofoils
    Autorzy:
    Szantyr, J. A.
    Biernacki, R.
    Flaszyński, P.
    Dymarski, P.
    Kraskowski, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/258826.pdf
    Data publikacji:
    2009
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    marine propulsors
    vortex generation
    numerical methods
    experimental techniques
    Opis:
    The article presents the results of the research project concerning the process of formation of the tip vortices shed from hydrofoils of different geometry in different flow conditions. Three hydrofoils resembling the contemporary marine propeller blades have been selected for the study. The experimental part of the project consisted of the LDA measurements of the velocity field in three cross-sections of the vortex generated by the hydrofoils in the cavitation tunnel. The numerical part of the project consisted of calculations of the corresponding velocity field by means of three computer codes and several selected turbulence models. The comparative analysis of the experimental and numerical results, leading to the assessment of the accuracy of the numerical methods, is included.
    Źródło:
    Polish Maritime Research; 2009, 3; 11-17
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An Experimental and Numerical Study of Tip Vortex Cavitation
    Autorzy:
    Szantyr, J. A.
    Flaszyński, P.
    Suchecki, W.
    Alabrudziński, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/260059.pdf
    Data publikacji:
    2011
    Wydawca:
    Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
    Tematy:
    rotary hydraulic machinery
    cavitation
    numerical methods
    experimental techniques
    Opis:
    The article presents the results of the research project concerning tip vortex cavitation. This form of cavitation is very important in operation of many types of rotary hydraulic machines, including pumps, turbines and marine propellers. Tip vortex cavitation generates noise, vibration and erosion. It should be eliminated or significantly limited during the design of these types of machines. The objective of the project was to develop an accurate and reliable method for numerical prediction of tip vortex cavitation, which could serve this purpose. The project consisted of the laboratory experiments and numerical calculations. Inthe laboratory experiments tip vortex cavitation was generated behind a hydrofoil in the cavitation tunneland the velocity field around the cavitating kernel was measured using the Particle Image Velocimetry method. Measurements were conducted in three cross-sections of the cavitating tip vortex for a number ofangles of attack of the hydrofoil and for several values of the cavitation index. In the course of numerical calculations two commercial CFD codes were used: Fluent and CFX. Several available approaches to numerical modeling of tip vortex cavitation were applied and tested, attempting to reproduce the experimental conditions. The results of calculations were compared with the collected experimental data. The most promising computational approach was identified. Keywords:
    Źródło:
    Polish Maritime Research; 2011, 4; 14-22
    1233-2585
    Pojawia się w:
    Polish Maritime Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Droplet Impact in Icing Conditions – Experimental Study for WE 540
    Autorzy:
    Lizer, T.
    Remer, M.
    Sobieraj, G.
    Psarski, M.
    Pawlak, D.
    Celichowski, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/139654.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    droplet
    icing
    wetting
    hydrophobicity
    experimental techniques
    kropelka
    oblodzenie
    zwilżanie
    hydrofobowość
    techniki eksperymentalne
    Opis:
    The work presents investigation on the water droplet impingement at a substrate with three different surface coating. The experiments are carried out for two temperatures of the surface: 23 degrees centigrade (room temperature) and 10 degrees centigrade. The water droplet contact is recorded via ultra-fast camera and simultaneously via fast thermographic camera. The wetting properties are changing for subzero temperatures of substrates.
    Źródło:
    Archive of Mechanical Engineering; 2017, LXIV, 2; 165-175
    0004-0738
    Pojawia się w:
    Archive of Mechanical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Separation of isochromatics and isoclinics phasemaps for the photoelastic technique with use phase shifting and a large number of high precision images
    Autorzy:
    Magalhaes, C. A.
    Neto, P. S.
    Magalhaes Jr P. A., A.
    de Barcellos, C. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/220820.pdf
    Data publikacji:
    2013
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    photoelasticity
    metrology
    stress analysis
    strain measurement
    optical measurement systems
    optical interferometry
    experimental techniques
    Opis:
    Digital photoelasticity is an important optical metrology follow-up for stress and strain analysis using full-field digital photographic images. Advances in digital image processing, data acquisition, procedures for pattern recognition and storage capacity enable the use of the computer-aided technique in automation and facilitate improvement of the digital photoelastic technique. The objective of this research is to find new equations for a novel phase-shifting method in digital photoelasticity. Some innovations are proposed. In terms of phaseshifting, only the analyzer is rotated, and the other equations are deduced by applying a new numerical technique instead of the usual algebraic techniques. This approach can be used to calculate a larger sequence of images. Each image represents a pattern and a measurement of the stresses present in the object. A decrease in the mean errors was obtained by increasing the number of observations. A reduction in the difference between the theoretical and experimental values of stresses was obtained by increasing the number of images in the equations for calculating phase. Every photographic image has errors and random noise, but the uncertainties due to these effects can be reduced with a larger number of observations. The proposed method with many images and high accuracy is a good alternative to the photoelastic techniques.
    Źródło:
    Metrology and Measurement Systems; 2013, 20, 1; 127-138
    0860-8229
    Pojawia się w:
    Metrology and Measurement Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Metody badań zapraw historycznych – problematyka konserwatorska
    Mortar historical research methods – problems of restoration
    Autorzy:
    Klimek, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/391280.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
    Tematy:
    badania zapraw historycznych
    metody badań
    schemat postępowania
    experimental method
    evaluation of restoration materials
    lime plasters
    experimental techniques of materials
    Opis:
    Historyczne zaprawy są cennym źródłem informacji o technikach budowlanych stosowanych w przeszłości. Są one interesujące dla architektów, technologów i archeologów, którzy wykorzystują zaprawy jako dodatkowe kryterium dla ustalenia chronologii budowy muru w zabytkowych budynkach. Zgodnie z celem badań, stosowane są określone metody analityczne w zależności od wybranego programu badań i prac. Podstawowym problemem jest niewielki zasób opracowanych materiałów mogących służyć do porównań, drugi problem wynika z braku właściwej oceny materiałów stosowanych do napraw i konserwacji w przeszłości. Obecnie w praktyce dla prowadzonych prac badawczych przyjęte i mierzone parametry określane są indywidualnie dla obiektu, lub wynikają ze specyfiki badań prowadzonych przez architektów, archeologów, konserwatorów. Niestety przy braku określonego schematu postępowania uzyskanych wyników nie można porównać
    Depending on various factors like time, increasing air pollution due to technological improvements of the present era together with insufficiency of inspection leads to the formation of damages on these buildings which are part of our historical heritage. Conservation of such buildings which are as important as historical documents should be the first and foremost target of any project. Plaster used in former time are a valuable source of information of building techniques used in the past. They are of interest to technologists and archaeologists, who use plasters as an additional criterion for establishing the chronology of the construction of walling in historic buildings. In accordance with the purpose of the investigations, appropriate analytical methods of a defined precision and specially chosen program are applied. The first dimension of the current problem is the insufficiency of resources while the second dimension stems from the lack of proper evaluation of the material to be used in conservation and restoration. This study defines the importance of mortars and plasters along with their history and the reasons of deterioration. In addition, it sets up the information flow of mortar and plaster within a systematic decision making process. The necessary experimental methods for the production of new repair mortar or plaster that can be used in determining the character analysis of original mortar and deterioration morphology are also analyzed. The necessity has been emphasized for the introduction of investigation standards to be universally binding, which would make it possible to compare the results of investigations carried out in different laboratories. The practice has been for analytical programs adopted and parameters measured to be individually chosen by the particular investigators and cannot be compare.
    Źródło:
    Budownictwo i Architektura; 2015, 14, 2; 63-69
    1899-0665
    Pojawia się w:
    Budownictwo i Architektura
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Regulation of GMO field trials in the EU and new genomic techniques: will the planned reform facilitate experimenting with gene-edited plants?
    Autorzy:
    Zimny, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/16687398.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    GMO
    experimental release
    field trial
    new genomic techniques
    risk assessment
    Opis:
    This study presents the possible consequences of maintaining the current regulatory regime of the experimental release of genetically modified higher plants in the EU for the products of new genomic techniques (NGTs). Currently, the experimental release is a crucial stage before the authorization of a product for the market. By analyzing the data on the performance of field trials in the EU (numbers, sizes, dominating countries) and comparing the present regulatory provisions with those of selected third countries (including new provisions adopted in the UK), this study shows that the current framework of GMO (genetically modified organisms) field trials is ill-fitted for breeding activities. Due to strict limitations placed on the operator of a field trial in the EU, easing the regulatory burdens on the authorization of certain NGT products for the market may not provide researchers (especially, plant breeders) the competitive position they need if the present legal conditions for carrying out GMO field trials with certain NGT products (especially, those that are considered GMOs covered by the EU GMO legislation) are not going to change as well.
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2023, 104, 1; 75-83
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Product design techniques in automotive production
    Autorzy:
    Dúbravčík, M.
    Babjak, Š
    Kender, Š.
    Powiązania:
    https://bibliotekanauki.pl/articles/117740.pdf
    Data publikacji:
    2012
    Wydawca:
    Polskie Towarzystwo Promocji Wiedzy
    Tematy:
    automotive
    experimental car
    innovation techniques integration
    innovation tools
    product design
    prototyping
    Opis:
    In the present and medium term perspective in the future, the mechanical engineering and other industrial branches are facing advanced challenges arising from global changes in the technical, economic and social environment. Submitted article deals with the approach to Product design in automotive sector that is using benefits from the synergic effect of utilizing the innovative methods, techniques and tools, within the integrated model of complex product development. The suggested paradigm is demonstrated on the project of experimental car ICAR 2010 at the Faculty of Mechanical Engineering, Technical University of Kosice, Slovakia.
    Źródło:
    Applied Computer Science; 2012, 8, 1; 77-91
    1895-3735
    Pojawia się w:
    Applied Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of two management techniques applied to the reduction of Juncus maritimus (Lam.) abundance in a selected temporary wetland
    Wpływ dwóch technik gospodarowania stosowanych do ograniczenia obfitości Juncus maritimus (Lam.) w wybranych okresowych środowiskach podmokłych
    Autorzy:
    Sahib, Nargis
    Powiązania:
    https://bibliotekanauki.pl/articles/292447.pdf
    Data publikacji:
    2019
    Wydawca:
    Instytut Technologiczno-Przyrodniczy
    Tematy:
    conservation of temporary wetlands
    experimental approach
    Juncus maritimus (Lam.)
    rush
    seed bank
    techniques of management
    bank nasion
    ochrona okresowych środowisk podmokłych
    podejście doświadczalne
    sitowie
    techniki zarządzania
    Opis:
    Moderate management of temporary wetlands is one of the most proper methods for their restoration and conservation. The cessation of use may lead to high biomass domination by macrophytes as Juncus maritimus (Lam.) that changes plant community structure, threatens species biodiversity, and becomes a danger for their conservation. The experiment was carried out in Sidi Boughaba coastal reserve in Morocco. Two management techniques of wetlands were tested, cutting and uprooting of the rush. Four experimental plots (4.2 × 2.9 m) within the rush belt were set up, with intact plots as a control. Vegetation structure and water levels were monitored on 96 quadrats over two years. The six visits dates, three visits per year (February, April, June), were monitored over two years. The abundance and richness of species were studied, simultaneously with the density of the seed stock in each plot. Results showed that both techniques allowed the opening of the habitat with a significant increase of richness and abundance of species, particularly the restoration of characteristic species of the temporary wetland from the seed bank. The cut technique seems to have less of an effect on the seed stock, total seeds median value was 6.5 in cut plots versus 5 in uprooting plots, being regularly applied given the rapid encroachment of the rush.
    Umiarkowane zarządzanie okresowymi środowiskami podmokłymi jest jedną z najbardziej właściwych metod ich odtwarzania i ochrony. Zaniechanie użytkowania może prowadzić do znaczącej dominacji biomasy makrofitów, takich jak Juncus maritimus, która zmienia strukturę zespołu roślinnego, ogranicza różnorodność gatunkową i stanowi zagrożenie dla ochrony siedlisk. Eksperyment prowadzono w przybrzeżnym rezerwacie Sidi Boughaba w Maroku. Testowano dwie techniki gospodarowania – cięcie i wykorzenianie sitowia. Założono cztery poletka doświadczalne (4.2 × 2.9 m) w pasie sitowia, stosując poletka bez jakichkolwiek zabiegów jako kontrolę. Strukturę roślinności i poziom wody monitorowano sześciokrotnie na 96 kwadratach w ciągu dwóch lat, trzykrotnie w ciągu roku (w lutym, kwietniu i czerwcu). Badano obfiobfitość i bogactwo gatunkowe oraz zagęszczenie banku nasion w każdym poletku. Wyniki dowodzą, że obie techniki umożliwiają otwarcie siedlisk ze znaczącym wzrostem bogactwa i obfitości gatunków, szczególnie przywracanie z banku nasion gatunków charakterystycznych dla siedlisk podmokłych. Technika wycinania skutkuje, jak się wydaje, słabszym wpływem na bank nasion, stosowana regularnie ułatwia gwałtowny rozrost sitowia.
    Źródło:
    Journal of Water and Land Development; 2019, 41; 120-132
    1429-7426
    2083-4535
    Pojawia się w:
    Journal of Water and Land Development
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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