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Wyszukujesz frazę "current velocity" wg kryterium: Wszystkie pola


Wyświetlanie 1-12 z 12
Tytuł:
Influence of ship motion on waterway. Backward current velocity
Autorzy:
Kulczyk, J.
Werszko, R.
Powiązania:
https://bibliotekanauki.pl/articles/260512.pdf
Data publikacji:
2006
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
waterway
bow form
backward current
Opis:
In this work was presented an influence of bow form of inland waterways ship and waterway limitations on values of backward current velocity. The analysis was performed on the basis of results of calculations with the use of numerical modeling the flow around ship hull. The applied HPSDK computation system (a computer software developed by these authors) is based on using surface distribution of vorticity to analyze the velocity field and pressure distribution around ship hull. It was proved that the generated backward current velocity exceeded its permissible non-scouring values.
Źródło:
Polish Maritime Research; 2006, S 2; 23-28
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Variability of currents over the southern slope of the Gulf of Finland
Autorzy:
Suhhova, I.
Pavelson, J.
Lagemaa, P.
Powiązania:
https://bibliotekanauki.pl/articles/48946.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
stratification
upwelling
downwelling
Finland Gulf
coastal sea water
seasonal thermocline
current velocity
Źródło:
Oceanologia; 2015, 57, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Phenotypic responses to water flow and wave exposure in aquatic plants
Autorzy:
Szmeja, J
Galka, A.
Powiązania:
https://bibliotekanauki.pl/articles/57001.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Botaniczne
Tematy:
water flow
aquatic plant
Polska
river
clonal growth
wave exposure
allocation
botany
current velocity
phenotypic variation
lake
Opis:
Plastic responses of 10 aquatic plant species from 5 rivers and 5 lakes in NW Poland were examined. Chara fragilis, C. delicatula, Potamogeton pectinatus, P. perfoliatus, P. natans, Spirodela polyrhiza, Hydrocharis morsus-ranae, Salvinia natans, Nymphoides peltata and Juncus bulbosus were the subject of research. In the running water of rivers, rhizophytes were generally bigger and they allocated from 0.6% to 58.6% more biomass for anchoring in the substrate than in stagnant water (ox bow lakes). In both flow variants rhizophytes allocated a similar biomass fraction for generative reproduction. On the other hand, under the influence of water flow pleustophytes reduced the mass of an individual (Spirodela by 25%, Hydrocharis 67%, Salvinia 77%) and emergent structures (p<0.001), and the number of sporangia (p<0.001). In both flow variants the input of biomass to generative reproduction was the same (Salvinia), or it was greater in running water (Hydrocharis; an increase from 4.9±1.3% to 15.1±3.6%). Under the conditions of strong wave action, in comparison with the lack of this environmental factor, Chara delicatula was several times shorter (p<0.001). However, it was also stouter, and as a result it had similar mass. In the areas of wave action the plant allocated 88.8% of its mass for anchoring in the substrate, whereas when there were no waves, only 22.7%.
Źródło:
Acta Societatis Botanicorum Poloniae; 2008, 77, 1
0001-6977
2083-9480
Pojawia się w:
Acta Societatis Botanicorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Three-dimensional underwater path planning based on modified potential field algorithm in time-varying current
Autorzy:
Wang, Shasha
Feng, Guilin
Wang, Dan
Tuo, Yulong
Powiązania:
https://bibliotekanauki.pl/articles/32917893.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
AUV
3D underwater path planning
time-varying current
modified artificial potential field
velocity synthesis
Opis:
The article addresses the three-dimensional (3D) underwater path planning problem of an autonomous underwater vehicle (AUV) in a time-varying current. A modified artificial potential field algorithm combining the velocity vector synthesis method is proposed to search for the optimal path. The modified potential field (MPF) algorithm is designed to dynamically plan the non-collision path. Meanwhile, this modified method is also proved to be an effective solution to the goals not reachable with obstacles nearby (GNRON), U-shaped trap, and rotation unreachable problems. To offset the influence of time-varying current, the velocity synthesis approach is designed to adjust the AUV movement direction. Besides, considering path planning in the complex underwater environment, the multi-beam forward-looking sonar (FLS) model is used. Finally, simulation studies substantiate that the designed algorithm can implement the AUV path planning effectively and successfully in a 3D underwater environment.
Źródło:
Polish Maritime Research; 2023, 1; 33-42
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Current observations from a looking down vertical V-ADCP: interaction with winds and tide? The case of Giglio Island (Tyrrhenian Sea, Italy)
Autorzy:
Cutroneo, L.
Ferretti, G.
Scafidi, D.
Ardizzone, G.D.
Vagge, G.
Capello, M.
Powiązania:
https://bibliotekanauki.pl/articles/47976.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
wind
tide
interaction
sea level
normalized cross-correlation function
wind velocity
current measurement
Giglio Island
Tyrrhenian Sea
Italy
Opis:
In the context of the environmental monitoring of the Concordia wreck removal project, measurements of currents, winds and sea level height were made along the eastern coast of the Giglio Island, Tyrrhenian Sea (Italy), during 2012—2013. The aim of the study was to investigate the effect of atmospheric forcing and periodic sea-level changes on the coastal currents. Normalised Cross-Correlation Function analysis allowed us to correlate these observations. A marked inter-seasonal variability was found in both current and local wind velocity observations but a significant level of correlation between the data was only found during strong wind events. Current and wind directions appeared to be uncorrelated and current measurements showed a predominant NW—SE direction, presumably linked to the shape and orientation of Giglio Island itself. During strong winds from the SSE, current flow was towards the NNW but it suddenly switched from the NNW to the SE at the end of wind events. The results show that, at Giglio Island, currents are principally dominated by the general cyclonic Tyrrhenian circulation, and, secondly, by strong wind events. The sea level had no effects on the current regime.
Źródło:
Oceanologia; 2017, 59, 2
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of Time Warping Algorithms for Rail Vehicle Velocity Estimation in Low Speed Scenarios
Autorzy:
Hensel, S.
Marinov, M. B.
Powiązania:
https://bibliotekanauki.pl/articles/221440.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
velocity estimation
cross-correlation
dynamic programming
eddy current sensors
Opis:
Precise measurement of rail vehicle velocities is an essential prerequisite for the implementation of modern train control systems and the improvement of transportation capacity and logistics. Novel eddy current sensor systems make it possible to estimate velocity by using cross-correlation techniques, which show a decline in precision in areas of high accelerations. This is due to signal distortions within the correlation interval. We propose to overcome these problems by employing algorithms from the field of dynamic programming. In this paper we evaluate the application of correlation optimized warping, an enhanced version of dynamic time warping algorithms, and compare it with the classical algorithm for estimating rail vehicle velocities in areas of high accelerations and decelerations.
Źródło:
Metrology and Measurement Systems; 2017, 24, 1; 161-173
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
ADCP-referenced geostrophic velocity and transport in the West Spitsbergen current
Autorzy:
Osinski, R.
Wieczorek, P.
Beszczynska-Moller, A.
Goszczko, I.
Powiązania:
https://bibliotekanauki.pl/articles/48340.pdf
Data publikacji:
2003
Wydawca:
Polska Akademia Nauk. Instytut Oceanologii PAN
Tematy:
Arctic circulation
Atlantic water
acoustic Doppler current profiler
geostrophic flow
West Spitsbergen current
Źródło:
Oceanologia; 2003, 45, 3
0078-3234
Pojawia się w:
Oceanologia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical study on two dimensional distribution of streamwise velocity in open channel turbulent flows with secondary current effect
Autorzy:
Mohan, S.
Kundu, S.
Ghoshal, K.
Kumar, J.
Powiązania:
https://bibliotekanauki.pl/articles/38616700.pdf
Data publikacji:
2021
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
velocity distribution
open channel flow
turbulent flow
RANS equations
secondary current
finite difference method
Opis:
For studying mechanism of sediment transport in river flows, open channel flow is a prototype. Flow has always three components of velocity for all types of channel geometry and for a time independent uniform flow along streamwise or main flow direction, all the components of velocity are functions of lateral and vertical coordinates. The present study investigates the two dimensional distribution of streamwise (or longitudinal) velocity starting from the Reynolds averaged Navier–Stokes equation for a turbulent open channel flow which is steady and uniform along the main flow direction. Secondary flows both along the vertically upward direction and along the lateral direction are considered which are also taken as functions of lateral and vertical coordinates. Inclusion of the secondary current brings the effect of dip phenomenon in the model. The resulting second order partial differential equation is solved numerically. The model is validated for all the cross-sectional, transverse and centreline velocity distribution by comparing with existing relevant set of experimental data and also with an existing model. Comparison results show good agreement with data as well as with the previous model proving the efficiency of the model. It is found that the transverse velocity distribution depends on the formation of circular vortex in the cross-sectional plane and becomes periodic as the number of circular vortex increases for increasing aspect ratios.
Źródło:
Archives of Mechanics; 2021, 73, 2; 175-200
0373-2029
Pojawia się w:
Archives of Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surrogate synthesis of excitation systems for frame tangential eddy current probes
Autorzy:
Halchenko, Volodymir Yakovych
Trembovetska, Ruslana Volodymyrivna
Tychkov, Volodymir Volodymyrovych
Powiązania:
https://bibliotekanauki.pl/articles/1955174.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
additive neural network regression
eddy current probe
stochastic optimization algorithm
surrogate optimization
uniform eddy current density distribution
velocity effect
addytywna regresja sieci neuronowej
sonda prądów wirowych
algorytm optymalizacji stochastycznej
optymalizacja zastępcza
równomierny rozkład gęstości prądów wirowych
efekt prędkości
Opis:
Existing scientific studies devoted to the design of eddy-current probes with a priori given configuration of the electromagnetic excitation field, which provide a uniform eddy current density distribution, consider a wide class of such, but are limited to the case when the probe is stationary relative to the testing object. Therefore, the actual problem is the synthesis of moving tangential eddy current probes with a frame excitation system that provides a uniform eddy current density distribution in the testing object, the solution of which is proposed in this study. A mathematical method for nonlinear surrogate synthesis of excitation systems for frame moving tangential surface eddy current probes, which implements a uniform eddy current density distribution of the testing zone object, is proposed. A metamodel of the volumetric structure of the excitation system of the frame tangential eddy current probe, applied in the process of surrogate optimal parametric synthesis, has been created. The examples of nonlinear synthesis of excitation systems using modern metaheuristic stochastic algorithms for finding the global extremum are considered. The numerical results of the obtained solutions of the problems are presented. The efficiency of the synthesized structures of excitation systems in comparison with classical analogs is shown on the graphs of the eddy current density distribution on the object surface in the testing zone.
Źródło:
Archives of Electrical Engineering; 2021, 70, 4; 743-757
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sediment transport beyond the surf zone under waves and currents of the non-tidal sea: Lubiatowo (Poland) case study
Autorzy:
Ostrowski, R.
Stella, M.
Powiązania:
https://bibliotekanauki.pl/articles/241109.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Instytut Budownictwa Wodnego PAN
Tematy:
wave-induced nearbed oscillations
sea currents
wind-driven current
sand grain diameter
bed shear stress
friction velocity
sediment transport
Opis:
The paper deals with the sandy coastal zone at Lubiatowo in Poland (the south Baltic Sea). The study comprises experimental and theoretical investigations of hydrodynamic and lithodynamic processes in the coastal region located close to the seaward boundary of the surf zone and beyond the surf zone. The analysis is based on field data collected at the IBW PAN Coastal Research Station in Lubiatowo. The data consist of wind velocity reconstructed from the long-term wave climate, deep-water wave buoy records and sea bottom soil parameters. Nearbed flow velocities induced by waves and currents, as well as bed shear stresses are theoretically modelled for various conditions to determine sediment motion regimes in the considered area. The paper discusses the possibility of occasional intensive sediment transport and the occurrence of distinct sea bed changes at bigger water depths.
Źródło:
Archives of Hydro-Engineering and Environmental Mechanics; 2016, 63, 1; 63-77
1231-3726
Pojawia się w:
Archives of Hydro-Engineering and Environmental Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Structure and local parameters of self-compressed plasma streams in external magnetic field
Autorzy:
Volkova, Yuliia
Solyakov, Dmytro
Marchenko, Anna
Chebotarev, Volodymyr
Garkusha, Igor
Makhlai, Vadym
Ladygina, Maryna
Tetyana, Merenkova
Yeliseyev, Dmytro
Petrov, Yurii
Staltsov, Valerii
Powiązania:
https://bibliotekanauki.pl/articles/2202565.pdf
Data publikacji:
2023
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
current sheet
electric probe
electron temperature
drift velocity
pinching discharge
plasma accelerators
Opis:
The influence of the external axial magnetic field on pinching plasma flows generated by a magnetoplasma compressor (MPC) has been studied using magnetic and electric probes. In the presence of an external magnetic field, temperature measurements show two groups of electrons with different temperatures near the plasma stream core. The external magnetic field leads to a noticeable increase in the electric current in the plasma stream, electron temperature, and the formation of the current-sheet-like structure observed in the MPC for the first time.
Źródło:
Nukleonika; 2023, 68, 1; 3--9
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of residual doping on surface current of InGaAs/InP photodiode passivated with regrown InP
Autorzy:
Braga, Osvaldo M.
Delfino, Cristian A.
Kawabata, Rudy M. S.
Pinto, Luciana D.
Vieira, Gustavo S.
Pires, Mauricio P.
Souza, Patricia L.
Marega, Euclydes
Carlin, John A.
Krishna, Sanjay
Powiązania:
https://bibliotekanauki.pl/articles/2204208.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
simulation
residual doping
recombination velocity
surface passivation
regrowth
Opis:
The viability of epitaxial regrowth of non-intentionally doped InP to passivate lateral mesa surfaces of InGaAs photodiodes lattice-matched to InP is investigated, evaluating whether the residual doping of the regrown layer can be responsible for un unexpected increase of the surface current. The effect of residual doping is evaluated via numerical calculations of dark current, considering the range of doping concentrations expected for non-intentionally doped InP. The calculations show that the increase in dark current due to the residual doping of the regrown InP layer is not enough to justify the observed increase in surface current. On the other hand, the technique is still valid as a passivation method if the photodetector pixel is isolated by etching only the top contact layer.
Źródło:
Opto-Electronics Review; 2023, 31, Special Issue; art. no. e144562
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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