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Wyświetlanie 1-15 z 64
Tytuł:
A nonlinear model of a turbine blade by asymptotic analysis
Autorzy:
Rodriguez, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/907896.pdf
Data publikacji:
2002
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
matematyka
asymptotic analysis
nonlinear elasticity
junctions
shallow shells
multistructures
Opis:
In this paper we obtain a limit model for a turbine blade fixed to a 3D solid. This model is a three-dimensional linear elasticity problem in the 3D part of the piece (the rotor) and a two-dimensional problem (the nonlinear shallow shell equations) in the 2D part (the turbine blade), with junction conditions in the part of the turbine blade fixed to the rotor. To obtain this model, we perform an asymptotic analysis, starting with the nonlinear three-dimensional elasticity equations on all the pieces and taking as a small parameter the thickness of the blade.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2002, 12, 1; 101-113
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An algebraic derivative associated to the operator $D^δ$
Autorzy:
Almeida, V.
Castro, N.
Rodríguez, J.
Powiązania:
https://bibliotekanauki.pl/articles/1207615.pdf
Data publikacji:
2000
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Opis:
In this paper we get an algebraic derivative relative to the convolution $(f*g)(t)=∫_0^ti f(t-ψ)g(ψ)dψ$ associated to the operator $D^δ$, which is used, together with the corresponding operational calculus, to solve an integral-differential equation. Moreover we show a certain convolution property for the solution of that equation
Źródło:
Banach Center Publications; 2000, 53, 1; 71-78
0137-6934
Pojawia się w:
Banach Center Publications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bio-methanization of organic fraction from municipal solid waste: temperature effects
Autorzy:
Fernández-Rodríguez, J.
Pérez, M.
Romero, L. I.
Powiązania:
https://bibliotekanauki.pl/articles/779264.pdf
Data publikacji:
2013
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
anaerobic digestion
OFMSW
mesophilic
thermophilic
methane
Opis:
The main objective of this study was to analyse the development of dry anaerobic digestion process of OFMSW in batch reactors under two temperature ranges, thermophilic (55°C) and mesophilic (35°C). The experimental results lead to the conclusion that the thermophilic range has a greater rate of hydrolysis and is therefore more effective to degrade wastes, shortening the overall operating time. For example, the hydrolytic step in the thermophilic (T) process lasted an average of 8 days versus 14 days in the mesophilic (M) range. The methanogenic phase lasted for 18 and 29 days in the T and M processes, respectively. The mesophilic range showed higher removal of the organic effluent but with greater uptime requirements. Moreover, the thermophilic range showed greater productivities than the mesophilic range, and the productivities were approximately doubled in terms of the produced biogas from a given amount of consumed organic matter.
Źródło:
Polish Journal of Chemical Technology; 2013, 15, 2; 99-106
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical model of so2 scrubbing with seawater applied to marine engines
Autorzy:
Lamas, M. I.
Rodríguez, C. G.
Rodríguez, J. D.
Telmo, J.
Powiązania:
https://bibliotekanauki.pl/articles/258856.pdf
Data publikacji:
2016
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
sulphur dioxide
SO2
scrubbers
CFD
Opis:
The present paper proposes a CFD model to study sulphur dioxide (SO2) absorption in seawater. The focus is on the treatment of marine diesel engine exhaust gas. Both seawater and distilled water were compared to analyze the effect of seawater alkalinity. The results indicate that seawater is more appropriate than distilled water due to its alkalinity, obtaining almost 100% cleaning efficiency for the conditions analyzed. This SO2 reduction meets the limits of SOx emission control areas (SECA) when operating on heavy fuel oil. These numerical simulations were satisfactory validated with experimental tests. Such data are essential in designing seawater scrubbers and judging the operating cost of seawater scrubbing compared to alternative fuels.
Źródło:
Polish Maritime Research; 2016, 2; 42-47
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis of the pre-injection system of a marine diesel engine through multiple-criteria decision-making and artificial neural networks
Autorzy:
Rodriguez, C. G.
Lamas, M. I.
Rodriguez, J. D.
Abbas, A.
Powiązania:
https://bibliotekanauki.pl/articles/2033205.pdf
Data publikacji:
2021
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
marine engine
emissions
consumption
artificial neural networks
multi-criteria decision making
computational fluid dynamics
Opis:
The present work proposes several pre-injection patterns to reduce nitrogen oxides in the Wartsila 6L 46 marine engine. A numerical model was carried out to characterise the emissions and consumption of the engine. Several pre-injection quantities, durations, and starting instants were analysed. It was found that oxides of nitrogen can be noticeably reduced but at the expense of increasing consumption as well as other emissions such as carbon monoxide and hydrocarbons. According to this, a multiple-criteria decision-making (MCDM) model was established to select the most appropriate parameters. Besides, an artificial neural network (ANN) was developed to complement the results and analyse a huge quantity of alternatives. This hybrid MCDM-ANN methodology proposed in the present work constitutes a useful tool to design new marine engines.
Źródło:
Polish Maritime Research; 2021, 4; 88-96
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of ancient forging devices: 3D modelling and analysis using current computer methods
Autorzy:
Rojas-Sola, J. I.
Bouza-Rodríguez, J. B.
Comesaña-Campos, A.
Powiązania:
https://bibliotekanauki.pl/articles/200411.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
forging device
hydraulic trompe
3D modelling
computational fluid dynamics
finite element analysis
urządzenie do kucia
modelowanie 3D
analiza elementów skończonych
Opis:
An ancient forging device in Spain has been studied, namely the forge with a waterwheel and air-blowing tube or hydraulic trompe, found near the village of Santa Eulalia de Oscos (province of Asturias, Spain). Three procedures using ad hoc methods were applied: 3D modelling, finite element analysis (FEA), and computational-fluid dynamics (CFD). The CFD results indicated the proper functioning of the trompe, which is a peculiar device based on the Venturi effect to take in air. The maximum air volume flow rate supplied to the forge by the trompe was shown to be 0.091 m3/s, and certain parameters of relevance in the trompe design presented optimal values, i.e. offering maximum air-flow supply. Furthermore, the distribution of stress over the motion-transmission system revealed that the stress was concentrated most intensely in the cogs of the transmission shaft (a kind of camshaft), registering values of up to 7.50 MPa, although this value remained below half of the maximum admissible work stress. Therefore, it was confirmed that the oak wood from which the motion system and the trompe were made functioned properly, as these systems never exceeded the maximum admissible working stress, demonstrating the effectiveness of the materials used in that period.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2019, 67, 2; 377-390
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical analysis of emissions from marine engines using alternative fuels
Autorzy:
Lamas, M. I.
Rodriguez, C. G.
Telmo, J.
Rodriguez, J. D.
Powiązania:
https://bibliotekanauki.pl/articles/260425.pdf
Data publikacji:
2015
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
fuel
natural gas
hydrogen
marine engine
emissions
Opis:
The current restrictions on emissions from marine engines, particularly sulphur oxides (SOx ), nitrogen oxides (NOx ) and carbon dioxide (CO2 ), are compelling the shipping industry to a change of tendency. In the recent years, many primary and secondary reduction techniques have been proposed and employed in marine engines. Nevertheless, the increasingly restrictive legislation makes it very difficult to continue developing efficient reduction procedures at competitive prices. According to this, the paper presents the possibility to employ alternative fuels. A numerical model was developed to analyze the combustion process and emissions using oil fuel, natural gas and hydrogen. A commercial marine engine was studied, the Wartsila 6L 46. It was found, that hydrogen is the cleanest fuel regarding CO2 , hydrocarbons (HC) and carbon monoxide (CO). Nevertheless, it is very expensive for marine applications. Natural gas is cheaper and cleaner than fuel oil regarding CO2 and CO emissions. Still, natural gas emits more NOx and HC than oil fuel. SOx depends basically on the sulphur content of each particular fuel.
Źródło:
Polish Maritime Research; 2015, 4; 48-52
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-dimensional cfd analysis to study the thrust and efficiency of a biologicallyinspired marine propulsor
Autorzy:
Lamas, M. I.
Rodríguez, J. D.
Rodríguez, C. G.
González, P. B.
Powiązania:
https://bibliotekanauki.pl/articles/259319.pdf
Data publikacji:
2011
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
fish swimming
marine propulsion
undulating fin
biomimetic
computational fluid dynamics (CFD)
CFD
Opis:
Aquatic animals, which are the result of many millions of years of evolutionary optimization, are very quick, efficient, robust, and versatile. Accordingly, biologically-inspired mechanisms which emulate the movement of animals have recently become very popular. For the efficient design of a propulsion system it is very important to analyze the fluid flow in detail. CFD (Computational Fluid Dynamics) has become a powerful technique to understand the phenomena because it gives extensive information about the fluid flow characteristics. In the present work, a propulsion system consisting of an undulating fin which emulates the fish swimming was built. In order to optimize the mechanism, several undulating configurations were studied using a 3D turbulent CFD model. The thrust, drag, efficiency and hydrodynamic characteristics were analyzed. Furthermore, it was shown that the efficiency and thrust depend strongly on the oscillation frequency, amplitude and wavelength. In order to validate this CFD model, the numerically obtained thrust was successfully compared with experimental results from the laboratory mechanism.
Źródło:
Polish Maritime Research; 2011, 1; 10-16
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Annual cycle of phytoplankton community through the water column: Study applied to the implementation of bivalve offshore aquaculture in the Southeastern Bay of Biscay
Autorzy:
Muniz, O.
Revilla, M.
Rodriguez, J.G.
Laza-Martinez, A.
Fontan, A.
Powiązania:
https://bibliotekanauki.pl/articles/47941.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
phytoplankton community
water column
open water
bivalve
biomass
chlorophyll a
nutrient
hydrographic condition
environmental variability
Biscay Bay
Źródło:
Oceanologia; 2019, 61, 1
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Performance analysis of an InAs/GaSb superlattice barrier photodetector covering the full LWIR spectral domain
Autorzy:
Alchaar, R.
Rodriguez, J.-B.
Höglund, L.
Naureen, S.
Costard, E.
Christol, P.
Powiązania:
https://bibliotekanauki.pl/articles/1818247.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
barrier photodetector
InAs/GaSb type-2 superlattice
long wavelength infrared
performance analysis
Opis:
In this paper, we present the electrical and electro-optical characterizations of an InAs/GaSb type-2 superlattice barrier photodetector operating in the full longwave infrared spectral domain. The fabricated detectors exhibited a 50% cut-off wavelength around 14 μm at 80 K and a quantum efficiency slightly above 20%. The dark current density was of 4.6×10⁻² A/cm² at 80 K and a minority carrier lateral diffusion was evaluated through dark current measurements on different detector sizes. In addition, detector spectral response, its dark current-voltage characteristics and capacitance-voltage curve accompanied by electric field simulations were analyzed in order to determine the operating bias and the dark current regimes at different biases. Finally, dark current simulations were also performed to estimate a minority carrier lifetime by comparing experimental curves with simulated ones.
Źródło:
Opto-Electronics Review; 2020, 28, 3; 164--170
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Assessment of a sheltered euhaline area of the Southeastern Bay of Biscay to sustain bivalve production in terms of phytoplankton community composition
Autorzy:
Bilbao, J.
Muniz, O.
Rodriguez, J.G.
Revilla, M.
Laza-Matinez, A.
Seoane, S.
Powiązania:
https://bibliotekanauki.pl/articles/2078991.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
phytoplankton community
phytoplankton composition
biomass
physicochemical variation
aquaculture
mussel
Biscay Bay
Opis:
This study describes the phytoplankton community in sheltered euhaline waters of the Basque coast (southeastern Bay of Biscay). Phytoplankton composition, cell size, abundance, biomass and the presence of potentially toxic taxa, together with chlorophyll a, nutrients and hydrographic and optical conditions were measured, from August 2016 to August 2017, in the Mutriku port, with the main aim of assessing the suitability of the phytoplankton community as a food resource for bivalves. The water column in Mutriku showed the typical environmental conditions of Basque marine waters, with no significant nutrient enrichment caused by anthropogenic pressures. Haptophytes represented the greatest contribution to cell abundance (31—47%), and diatoms were the dominant group in terms of biomass (52—79%), which could favour mussel growth due to their high fatty acid content. In addition, the size structure of the phytoplankton community was suitable for mussel ingestion, since the predominant cell size was 2—20 μm. Regarding toxic phytoplankton, the genera that pose a risk for human health and those that affect negatively mussel physiology and survival were considered. Altogether, ten toxic phytoplankton taxa were identified, contributing in less than 5% to the total cell abundance of Mutriku. However, median chlorophyll a concentration was low (0.5 μg L−1), reflecting the oligotrophic conditions of the area. Therefore, even if the composition of the phytoplankton community could be favourable for bivalve aquaculture, biomass values are low compared to other zones of bivalve production.
Źródło:
Oceanologia; 2021, 63, 1; 12-26
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inhomogeneity detection in phytoplankton time series using multivariate analyses
Autorzy:
Muniz, O.
Rodriguez, J.G.
Revilla, M.
Laza-Martinez, A.
Seoane, S.
Franco, J.
Powiązania:
https://bibliotekanauki.pl/articles/2079181.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
phytoplankton community
monitoring programme
uncertainty
multivariate analysis
inhomogeneity
Opis:
Phytoplankton communities have long been used as water quality indicators within environmental policies. This has fostered the development of national and international phytoplankton monitoring programs, but these networks are subject to sources of uncertainty due to laboratory issues. Nevertheless, studies regarding the interference associated with these aspects are not well-documented. Hence, a long time series (2003–2015) from the Basque continental shelf (southeastern Bay of Biscay) was analyzed to evaluate the uncertainty given by laboratory strategies when studying phytoplankton variability. Variability in phytoplankton communities was explained not only by environmental conditions but also by changes in fixatives (glutaraldehyde and acidic Lugol's solution) and laboratory staff. Based on Bray-Curtis distances, phytoplankton assemblages were found to be significantly dissimilar according to the effect of changes in the specialist handling the sample and the employed fixative. The pair-wise permutational multivariate analysis of variance (PERMANOVA) showed significant differences between the two fixatives utilized and also between the three taxonomists involved. Thus, laboratory-related effects should be considered in the study of phytoplankton time series.
Źródło:
Oceanologia; 2020, 62, 3; 243-254
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Eocene and not Cretaceous origin of spider wasps: fossil evidence from amber
Autorzy:
Rodriguez, J.
Waichert, C.
Von Dohlen, C.D.
Poinar,Jr., G.
Pitts, J.P.
Powiązania:
https://bibliotekanauki.pl/articles/20131.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Eocene
Cretaceous
spider wasp
pompilid wasp zob.spider wasp
fossil evidence
amber
Hymenoptera
Pompilidae
Opis:
Spider wasps had long been proposed to originate in the Late Cretaceous based on the Burmese amber fossil Bryopompilus interfector. We performed a morphological examination of this fossil and determined that it does not belong to Pompilidae or any other described hymenopteran family. Instead, we place it in the new family Bryopompilidae. The oldest verifiable member of the Pompilidae is from Baltic amber, which suggests that the crown group of the family probably originated in the Eocene, not in the Late Cretaceous as previously proposed. The origin of spider wasps appears to be correlated with an increase in spider familial diversity in the Cenozoic. We also add two genera to the extinct pompilid fauna: Tainopompilus Rodriguez and Pitts gen. nov. and Paleogenia Waichert and Pitts gen. nov., and describe three new species of fossil spider wasps: Anoplius planeta Rodriguez and Pitts sp. nov., from Dominican amber (Burdigalian to Langhian); Paleogenia wahisi Waichert and Pitts sp. nov., from Baltic amber (Lutetian to Priabonian); and Tainopompilus argentum Rodriguez and Pitts sp. nov., from Dominican amber (Chattian to Langhian).
Źródło:
Acta Palaeontologica Polonica; 2016, 61, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Kelvin-Helmholtz instabilities in the Colorado River Delta, Gulf of California
Autorzy:
Carbajal, N.
Vargas, J.T.
Rodriguez, J.H.G.
Montano Ley, Y.
Salas de Leon, D.A.
Powiązania:
https://bibliotekanauki.pl/articles/2078904.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Kelvin-Helmholtz instability
Colorado River Delta
tidal current
bottom sediment
bathymetry
suspended sediment
satellite image
Opis:
In the Colorado River Delta, the interaction of tidal currents and sea-bottom sediment formed, in geological times, large-scale seabed patterns known as sandbanks. These patterns are oriented along the delta, almost parallel to the dominant tidal flow, with the bathymetry having an undulating character across the delta. Calculations and analysis showed that the interaction of tidal currents with the bathymetry causes velocity shears, faster flowing over the ridges than in the troughs. Kelvin-Helmholtz instabilities emerge from the velocity shear, and a large amount of suspended sediment makes the instabilities visible in satellite images. The physical and dynamic conditions allowed us to find an explanation for the existence of these Kelvin-Helmholtz instabilities. Since sandbanks have been observed in different seas such as the North Sea, The Gulf of Korea, the Gulf of Khambhat in India, the Jiangsu coast in China, the Persian Gulf, and Moreton Bay in Australia, the results suggest the existence of instabilities in these areas. Satellite images, intense tidal currents, undulating topography, and suspended sediment made it possible to explain the generation and identification of KelvinHelmholtz instabilities.
Źródło:
Oceanologia; 2021, 63, 3; 321-328
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Relation between strain hardening of steel and critical impact velocity in tension
Zależność między umocnieniem odkształceniowym stali a krytyczną prędkością uderzenia przy rozciąganiu
Autorzy:
Rodriguez-Martinez, J. A.
Rusinek, A.
Arias, A.
Powiązania:
https://bibliotekanauki.pl/articles/279460.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
critical impact velocity
RK model
dynamic tension
Opis:
In the present paper, a numerical study on the influence of strain hardening on the Critical Impact Velocity (CIV) in tension is conducted. Finite element code ABAQUS/Explicit is used to carry out numerical simulations of dynamic tension tests in a wide range of impact velocities up to that corresponding to the CIV. The constitutive relation due to Rusinek and Klepaczko (2001) has been used to define the material behaviour. Strain hardening parameters of the RK model were varied during the simulations. Numerical results are compared with those obtained from the analytical description of CIV proposed by Klepaczko (2005). Satisfactory agreement is found between numerical and analytical approaches. The analysis allows for a better understanding of the causes responsible of the CIV appearance.
Praca przedstawia numeryczną analizę wpływu umocnienia odkształceniowego na krytyczną prędkość uderzenia (CIV) przy rozciąganiu. W symulacjach zastosowano oprogramowanie ABAQUS/Explicit oparte na metodzie elementów skończonych. Obliczeń dokonano dla dynamicznych obciążeń rozciągających w szerokim zakresie prędkości uderzenia aż do osiągnięcia wartości krytycznej (CIV). Do opisu materiału próbki użyto równań konstytutywnych modeli Rusinka-Klepaczki. Podczas analizy zmieniano parametry umocnienia odkształceniowego opisanego tym modelem. Wyniki symulacji numerycznych porównano z analitycznym opisem CIV zaproponowanym przez Klepaczkę (2005). Uzyskano zadawalającą zgodność pomiędzy symulacją a teorią. Przedstawiona analiza przyczynia się do lepszego zrozumienia zjawisk odpowiedzialnych za powstawanie krytycznej prędkości uderzenia (CIV).
Źródło:
Journal of Theoretical and Applied Mechanics; 2009, 47, 3; 645-665
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 64

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