Search results for "oceanic"
showing 10 items of 642 documents
Scattered Radiation in the Atmosphere and the Natural Aerosol
1964
Publisher Summary This chapter deals with problems of scattered atmospheric radiation, with regard to the haze in the atmosphere. The impressive phenomenon of the tint of the sky, which varies with the time of day and with the weather situation, has long stimulated the investigation of the radiation of the sky. As it is known that the sky radiation is in part, strongly polarized and that the degree of polarization is subjected to characteristic variations, these facts are included in the investigation. The atmospheric transparency for radiation and especially the radiation effects as related to aerosols of certain sizes are of fundamental importance. Reflected and scattered radiations are e…
Atmospheric turbidity and its spectral extinction
1955
The indices of the wavelength dependency of the haze extinction which were currently determined from measurements of solar radiation and visibility at Mainz, show pronounced seasonal variations. The summer values are in general definitely higher than in winter. There is no connection with the scatter light types of the sky-light or with the meteorological situation.
Interesting dematiaceous Hyphomycetes on Lodoiceamaldivica dead fragments
2013
Two new species, Virgariella lodoicea and Cacumisporium oceanicum and a new record of Diplocladiella scalaroides from Seychelles islands are proposed. A species of Helicosporium which could not be determined is also described.
A heuristic model-based approach for compensating wind effects in ski jumping.
2021
Wind influences the jump length in ski jumping, which raises questions about the fairness. To counteract the wind problem, the International Ski Federation has introduced a wind compensation system in 2009: time-averaged wind velocity components tangential to the landing slope are obtained from several sites along the landing slope, and these data are used in a linear statistical model for estimating the jump length effect of wind. This is considered in the total score of the ski jump. However, it has been shown that the jump length effect estimates can be inaccurate and misleading. The present manuscript introduces an alternative mathematical wind compensation approach that is based on an …
Simulations of an inhomogeneous stellar wind interacting with a pulsar wind in a binary system
2014
Binary systems containing a massive star and a non-accreting pulsar present strong interaction between the stellar and the pulsar winds. The properties of this interaction, which largely determine the non-thermal radiation in these systems, strongly depend on the structure of the stellar wind, which can be clumpy or strongly anisotropic, as in Be stars. We study numerically the influence of inhomogeneities in the stellar wind on the structure of the two-wind interaction region. We carried out for the first time axisymmetric, relativistic hydrodynamical simulations, with Lorentz factors of ~6 and accounting for the impact of instabilities, to study the impact in the two-wind interaction stru…
Assessment of synthetic winds through spectral modeling and validation using FAST
2016
In this paper, we analyse the simulated and measured wind data with respect to their spectral characteristics and their effect on wind turbine loads. The synthetic data is generated from a stochastic full-field turbulent wind simulator - TurbSim for neutral stability conditions. We first investigate a model for velocity spectra and, a coherence model, by comparing the model results with the measurements. In the second part we analyse the synthetic data via spectra and coherence for two cases; without and with adding coherent events. Finally, we compare wind turbine loads calculated by using FAST simulation of 5 MW reference wind turbine on the basis of simulated and measured data for the gi…
Wind- and tide-induced currents in the Stagnone Lagoon (Sicily)
2011
The hydrodynamic circulation is analyzed in the coastal lagoon of Stagnone di Marsala, a natural reserve located in the north-western part of Sicily, using both experimental measurements and numerical simulations. Field measurements of velocities and water levels, carried out using an ultrasound sensor (3D), are used to validate the numerical model. A 3D finite-volume model is used to solve the Reynolds-averaged momentum and mass balance differential equations on a curvilinear structured grid, employing the k– $${\varepsilon}$$ turbulence model for the Reynolds stresses. The numerical analysis allows to identify the relative contribution of the forces affecting the hydrodynamic circulation …
A laboratory and theoretical study on the uptake of sulfur dioxide gas by small water drops containing hydrogen peroxide under laminar and turbulent …
2000
Abstract Laboratory experiments are described where the uptake of SO2 gas by water drops containing H2O2 is investigated where the taken up S(IV) is quickly converted to S(VI). During the gas uptake the drops were freely suspended at their terminal velocity by means of the Mainz vertical wind tunnel. Two series of experiments were carried out, one with a laminar air flow in the wind tunnel, one with a turbulent air flow in the wind tunnel. Afterwards, the experimental results were compared against model computations using the so-called fully mixed convective diffusion model. The experimental results for laminar flow conditions showed that the fully mixed convective diffusion model for the u…
New stage-discharge relationships for radial gates
2013
Calibration of gates under free and submerged flow regimes is a classical hydraulic problem. In this paper dimensional analysis was applied to investigate both free and submerged flow conditions through a radial gate. The original Ferro’s method for submerged flow regime was modified by introducing the maximum allowable tail water depth permitting free flow. Based on Buckingham theorem and applying the Incomplete Self Similarity (ISS) concept different forms of the dimensional equations were proposed. According to the current available experimental data the most accurate dimensionless formula was proposed. The proposed dimensional equation not only is more accurate than the original Ferro’s…
Flow resistance ofPosidonia oceanicain shallow water
2006
Management of coastal waters and lagoons by mathematical circulation models requires determination of the hydraulic resistance of submerged vegetation. A plant typical of sandy coastal bottoms in the Mediterranean Sea is Posidonia oceanica, which is constituted by very thin and flexible ribbon-like leaves, about 1 cm wide and up to 1.5 m long, and usually covers the bottom with a density of 500-1000 plants/ m2. From the hydraulic viewpoint, P. oceanica constitutes a particular roughness, because, as the velocity increases, the leaves bend more and more until they lie down on the bottom. Although P. oceanica is widespread, in the technical literature it is difficult to find indications about…