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Wyszukujesz frazę "Lewińska, J." wg kryterium: Autor

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    Wyświetlanie 1-12 z 12
    Tytuł:
    Transport Properties of Disordered Graphene Layers
    Autorzy:
    Gryglas-Borysiewicz, M.
    Jouault, B.
    Tworzydło, J.
    Lewińska, S.
    Strupiński, W.
    Baranowski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1791293.pdf
    Data publikacji:
    2009-11
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.21.Ac
    72.20.Fr
    73.43.Qt
    73.63.Bd
    Opis:
    Samples consisting of a few layers of graphene obtained by thermal decomposition of SiC were studied by means of transport experiments at 4 K and in a magnetic field up to 7 T. Transport data show that the samples have a two-dimensional character. Magnetoresistance has an approximately linear character at high magnetic fields, which has been previously observed in graphite samples, and a negative magnetoresistance, at low magnetic fields. The transverse resistivity $ρ_{xy}$ is nonlinear as a function of B, which can be described using a many-carrier model.
    Źródło:
    Acta Physica Polonica A; 2009, 116, 5; 838-840
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transport in GaAs/AlAs/GaAs [111] Tunnel Junctions
    Autorzy:
    Lewińska, S.
    Gryglas-Borysiewicz, M.
    Przybytek, J.
    Baj, M.
    Jouault, B.
    Gennser, U.
    Ouerghi, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2047930.pdf
    Data publikacji:
    2011-05
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    73.61.-r
    71.20.Nr
    73.23.Hk
    73.63.Hs
    72.10.Di
    85.30.Mn
    73.40.Gk
    Opis:
    Resonant tunneling in single-barrier GaAs/AlAs/GaAs junctions grown in [111] direction was studied for samples with different concentration of silicon δ-doping in AlAs. In the I(V) characteristics, measured at 4 K, two kinds of peaks were observed: related to resonant tunneling via donors states in the barrier, and through X-minimum quantum well subbands. The results are compared to those previously obtained for analogous samples grown along [001] direction. The investigations reveal different symmetry of donor states in both cases.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 5; 606-608
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The influence of fuel injection pump malfunctions of a marine 4-stroke diesel engine on composition of exhaust gases
    Autorzy:
    Lewińska, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/133162.pdf
    Data publikacji:
    2016
    Wydawca:
    Polskie Towarzystwo Naukowe Silników Spalinowych
    Tematy:
    marine diesel engine
    malfunctions
    fuel injection pump
    exhaust gas
    silnik okrętowy
    usterki
    pompa wtryskowa
    spaliny
    Opis:
    The article presents results of a laboratory study on exhaust gas emission level from a marine diesel engine. The object of the laboratory study was a four-stroke marine diesel engine type Al 25/30 Sulzer, operated at a constant speed. The examination on the engine was carried out according to regulations of the Annex VI to MARPOL 73/78 Convention. The laboratory study consisted of 3 observations: the engine assumed to be operating without malfunctions, delay of the fuel injection by 5° of crankshaft angle in the second engine cylinder, and the leakage of the fuel pump on the second engine cylinder. Additionally, parameters of fuel consumption and thermodynamic parameters of the marine engine were measured during the research. Simulated malfunctions caused changes in total weighed NOx, CO, and CO2 emissions for all considered engine loads. All simulated malfunctions caused a small change in measured thermodynamic parameters of the engine. The engine operation with the delayed fuel injection and the fuel leakage in the fuel pump in one cylinder caused a decrease of NOx and CO emission level. Fuel leakage in the fuel pump causes the CO2 emission to decrease only at low engine load. Calculations of the weighed specific fuel consumption present a 1-2% change in the engine efficiency.
    Źródło:
    Combustion Engines; 2016, 55, 4; 53-57
    2300-9896
    2658-1442
    Pojawia się w:
    Combustion Engines
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Characteristic of Sound Reflections from Curved Reflective Panels
    Autorzy:
    Szeląg, A.
    Kamisiński, T.
    Lewińska, M.
    Rubacha, J.
    Pilch, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/177712.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sound reflection
    reflective panels
    sound scattering
    Opis:
    The paper presents the verification of a solution to the narrow sound frequency range problem of flat reflective panels. The analytical, numerical and experimental studies concerned flat panels, panels with curved edges and also semicircular elements. There were compared the characteristics of sound reflected from the studied elements in order to verify which panel will provide effective sound reflection and also scattering in the required band of higher frequencies, i.e. above the upper limit frequency. Based on the conducted analyzes, it was found that among some presented solutions to narrow sound frequency range problem, the array composed of panels with curved edges is the most preferred one. Nevertheless, its reflection characteristic does not meet all of the requirements, therefore, it is necessary to search for another solution of canopy which is effective over a wide frequency range.
    Źródło:
    Archives of Acoustics; 2014, 39, 4; 549-558
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Structural and magnetic properties of MBE grown (Fe/Pt) (111) multilayers
    Autorzy:
    Marynowska, A.
    Dynowska, E.
    Lewińska, S.
    Seki, T.
    Takanashi, K.
    Kanak, J.
    Pietruczik, A.
    Aleszkiewicz, P.
    Wawro, A.
    Ślawska-Waniewska, A.
    Baczewski, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/1058152.pdf
    Data publikacji:
    2016-12
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    61.05.cp
    61.05.jh
    68.35.bd
    68.35.Ct
    68.37.Ef
    68.37.Ps
    68.65.Ac
    75.50.Bb
    75.70.Ak
    Opis:
    Series of Al₂O₃(0001)/Pt/(Fe/Pt)ₙ/Pt multilayers with variable number of bilayers n and thicknesses of individual layers were grown using molecular beam epitaxy to investigate influence of buffer layer structure, number of bilayers, and individual layer thickness on their structural and magnetic properties. Both columnar and monocrystalline 10 nm Pt (111) buffer layers were used in the experiment. Structure of Pt buffer layer determined the roughness of Fe/Pt interfaces and consequently magnetic properties of the multilayers. When multilayers were deposited on columnar Pt buffer layer, we observed increase of Fe/Pt interfaces roughness with increasing number of bilayers to values exceeding the nominal Fe/Pt bilayer thickness in the upper part of the sample volume, which resulted in the increment of coercivity in the sample with n=15 determined from hysteresis loops measured for perpendicular orientation of magnetic field. When Fe/Pt multilayers were deposited on monocrystalline Pt buffer layer, Fe/Pt interfaces were smooth regardless the number of bilayers. All samples, despite of the quality of buffer layer, number of bilayers, and individual layer thickness revealed easy magnetisation axis oriented in the sample plane.
    Źródło:
    Acta Physica Polonica A; 2016, 130, 6; 1363-1370
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Recent developments of non-direct methods of pipeline and leak detection
    Autorzy:
    Fąfara, Z.
    Lewandowska-Śmierzchalska, J.
    Matuła, R.
    Lewińska, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/298717.pdf
    Data publikacji:
    2018
    Wydawca:
    Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
    Tematy:
    non-direct methods
    pipelines
    leaks detection
    risk management
    Opis:
    Industrial pipelines are used as a low-cost method of transport of various types of substances. In the last decades the number of transmission and distribution pipelines increased considerably, leading to an increased number of failures and rising the need for better and more accurate non-destructive methods of their detection and prevention. Leakage in pipeline networks causes a loss of valuable resources in the form of oil and gas. Repairing the infrastructure requires significant additional financial resources. Therefore, any damage to the pipeline network must be detected and repaired as soon as possible. Indirect methods for leak detection and localization uncover the presents of leaks from outside the pipeline by visual observation or by using appropriate equipment. Pipelines are often underground installations or run for many kilometers in areas where there are no roads, and access is extremely difficult or impossible. The underground occurrence of pipelines makes regular inspection difficult. It is also not possible to examine all pipeline sections simultaneously. Pipeline preventive maintenance or replacement program should be conducted based on detailed assessment of its technical and environmental conditions. Thus, safe and non-destructive techniques are needed, which would allow for pipeline periodical inspection without disturbing their operation.
    Źródło:
    AGH Drilling, Oil, Gas; 2018, 35, 1; 173-180
    2299-4157
    2300-7052
    Pojawia się w:
    AGH Drilling, Oil, Gas
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of the marine 4-stroke diesel engine malfunctions of the air and exhaust duct on the composition of exhaust gas
    Autorzy:
    Lewińska, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/241541.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Opis:
    Malfunctions of an intake air duct and an exhaust gas duct have negative impact on the operation of a diesel engine. The article presents results of a laboratory study on nitric oxides (NOx), carbon monoxide (CO) and carbon dioxide (CO2) emission levels from a marine four-stroke diesel engine. CO and CO2 emission levels are connected with oxygen content and specific fuel consumption. For this reason, the results of the laboratory study present oxygen fraction in exhaust gas and specific fuel consumption. The object of the study was laboratory piston engine, operating at constant speed. The measured engine parameters were carried out according to the regulations of the Annex VI to MARPOL 73/78 Convention. The study consisted of tests during engine operation without malfunctions and engine operation with simulated malfunctions. The laboratory study consisted of 3 observations: the engine assumed as operated without malfunctions, throttling of the exhaust gas duct by rotational barrier about 56° and throttling of the air intake duct by reducing of its cross section area by 60%. The simulated malfunctions caused changes in the total weighted NOx and CO emissions in all considered engine loads. All simulated malfunctions resulted in a decrease of all mentioned emission levels in the composition of exhaust gases during the operation at low engine loads and an increase of the CO2 emission level at the maximum engine load operation. The oxygen fraction decrease was observed for throttling of the intake air duct. The calculations of the weighted specific fuel consumption present a 2-3% change in the engine efficiency.
    Źródło:
    Journal of KONES; 2015, 22, 3; 141-148
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Influence of the marine 4 - stroke diesel engine malfunctions on the nitric oxides emission
    Autorzy:
    Lewińska, J.
    Kowalski, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/247875.pdf
    Data publikacji:
    2013
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    emission
    malfunction
    piston engine
    marine engine
    nitric oxides
    Opis:
    The article presents the results of the laboratory study on nitric oxides (NOx) emission level from marine fourstroke diesel engine. The object of the study was laboratory piston engine, operating at constant speed. Measured engine parameters were necessary to determine the NOx emission in accordance of the requirements of the Annex VI to MARPOL 73/78 Convention. The study consisted of tests during the engine operation without malfunctions and engine operation with simulated malfunctions. Malfunctions of the charge gas exchange in the form of throttling of the air intake duct and the throttling of the exhaust gas duct were taken into account in the simulations. Measurements during the engine operation with simulated malfunctions of the fuel pump on one of the cylinders were also carried out. Mentioned malfunctions were delay of the fuel injection by 5° of the crankshaft angle position and the leakage of the fuel pump of the second engine cylinder. The simulated malfunctions decrease the total weighted NOx emission in all considered the engine loads. All simulated malfunctions resulted in an increase of the NOx emissions during engine operation at low the engine loads and a decrease of the mentioned emission at maximum the engine loads operation. The calculations of the weighted specific fuel consumption present a little change in engine efficiency which are within the range of measuring error of the used method.
    Źródło:
    Journal of KONES; 2013, 20, 1; 171-177
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the microstructure of the fuel spray atomized by marine injector
    Autorzy:
    Lewińska, J.
    Kapusta, Ł. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/133889.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Naukowe Silników Spalinowych
    Tematy:
    marine diesel engine
    marine injector
    microstructure spray parameters
    optical method
    LIF/Mie
    okrętowy silnik spalinowy
    wtryskiwacz
    metoda optyczna
    Opis:
    The process of the atomization and formation of the fuel spray can be described by macro- and microstructure parameters. Knowledge of these parameters may be a key information to conduct further optimization of the combustion process. This paper presents the research results of the microstructure parameters of the diesel oil spray atomized with marine engine injector. A measurement technique, named Laser Induced Fluorescence (LIF) in the combination with Mie scattering was used to determine LIF/Mie ratio across the spray. The fuel was injected into a constant volume vessel. LIF and Mie signals were recorded by two cameras at the same time. Nd:YAG pulsed laser was used to create light sheet for spray illumination. Wavelength of λ = 266 nm was used in this study.
    Źródło:
    Combustion Engines; 2017, 56, 2; 120-124
    2300-9896
    2658-1442
    Pojawia się w:
    Combustion Engines
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of measurement methods for fuel injection spray parameters from marine engine injector
    Autorzy:
    Lewińska, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/242247.pdf
    Data publikacji:
    2016
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    marine diesel engine
    spray characteristics
    optical methods
    Mie scattering
    shadowgraphy
    Opis:
    One of the main factors influencing on the optimal combustion process in a marine diesel engine’s cylinder is the fuel injection spray and the fuel atomization. The complexity of mentioned phenomena in the marine diesel engine’s cylinder may cause difficulties in their analysis. Measurement methods, allowing obtaining information about the process of fuel injection and evaporation in the diesel engine’s cylinder are qualified as optical visualization methods. It provides non-invasive measurement of parameters of fuel injection spray. The article presents the analysis of various aspects of optical measurement methods application that allow specifying parameters of fuel injection spray in the diesel engine’s cylinder. Initial studies were carried out using Mie scattering method. In addition, visualization obtained by shadowgraphy method was presented also. The constant volume chamber was used as a working area. The conventional light source was used in case of Mie scattering and a laser light source in shadowgraphy. For the lighting test was used a double-pulse Nd:YAG laser. The wavelength laser 532 nm was used. A course of the injection process was recorded by high-speed camera. The Mie scattering method allows analysing the fuel injection phenomena in macro scale. Specified geometric parameters. The shadowgraphy method allows to asses parameters of diesel fuel injection from marine diesel engine’s injector in the micro scale.
    Źródło:
    Journal of KONES; 2016, 23, 4; 275-282
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Accuracy of merging point clouds at the maximum range of a scanner with limited possibilities of target placement
    Dokładność łączenia chmur punktów dla pomiaru na odległościach zbliżonych do rzeczywistego zasięgu skanera przy ograniczonej możliwości usytuowania targetów
    Autorzy:
    Lenda, G.
    Lewińska, P.
    Siwiec, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/230268.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    skanowanie laserowe
    zasięg daleki
    cel
    dokładność rejestracji
    chmura punktów
    laser scanning
    long range
    target
    registration accuracy
    point cloud
    Opis:
    The research was aimed at analysing the factors that affect the accuracy of merging point clouds when scanning over longer distances. Research takes into account the limited possibilities of target placement occurring while scanning opposite benches of quarries or open-pit mines, embankments from opposite banks of rivers etc. In all these cases, there is an obstacle/void between the scanner and measured object that prevents the optimal location of targets and enlarging scanning distances. The accuracy factors for cloud merging are: the placement of targets relative to the scanner and measured object, the target type and instrument range. Tests demonstrated that for scanning of objects with lower accuracy requirements, over long distances, it is optimal to choose flat targets for registration. For objects with higher accuracy requirements, scanned from shorter distances, it is worth selecting spherical targets. Targets and scanned object should be on the same side of the void.
    Badania miały na celu przeanalizowanie czynników wpływających na dokładność łączenia chmur punktów przy pomiarze obiektów na większych odległościach, przy ograniczonej możliwości rozmieszczenia targetów. Sytuacje takie mogą występować np. podczas skaningu w kamieniołomach lub kopalniach odkrywkowych, kiedy pomiar odbywa się z przeciwległych teras wyrobiska. Mogą pojawić się również podczas skanowania obwałowań, umocnień brzegów czy innych elementów infrastruktury z przeciwległego brzegu rzek czy zbiorników wodnych. Podobna sytuacja może wystąpić podczas pomiarów rozmaitych wydłużonych obiektów i budowli położonych po drugiej stronie tras komunikacyjnych. We wszystkich tych przypadkach pomiędzy stanowiskami skanera a mierzonym obiektem pojawia się przeszkoda/pustka, uniemożliwiająca optymalne usytuowane targetów łączących chmury punktów i zwiększająca odległości, na których wykonywany jest skaning. Czynnikami wpływającymi na dokładność łączenia chmur są w takich przypadkach: rozmieszczenie targetów względem siebie, skanera i mierzonego obiektu, rodzaj targetów oraz zasięg instrumentów. Zostały one uwzględnione w przeprowadzonych badaniach, mających wyłonić optymalną konfigurację pomiarową.
    Źródło:
    Archives of Civil Engineering; 2019, 65, 4; 229-248
    1230-2945
    Pojawia się w:
    Archives of Civil Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-12 z 12

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