The role of the power law exponent in wind energy assessment: A global analysis

Quantitative estimates on the ozone production efficiency (OPE) per a molecular of NOx (=NO+NO2), ΔP, and ozone production rate, PQ, are derived for the region of Central Siberia based on near surface observations of O3, NO, and NO2) at Zotino Tall Tower Observatory in 2007-2015. Experimental data follow are a power law dependencies on NOx abundance: PQ χ [NOx]-n+1, ΔP χ [NOx]-n, n = 0,82±0,06 (coefficient of determination R2 = 0,66), with the power law exponent corresponding to a NOx-limiting regime of ozone production in a weakly polluted air mass. During summer, the value of ΔP ranges from 30,0-43,7 [mol.O3/mol.NOx] which agrees well with the corresponding estimate of 39,8 [mol.O3/mol.NOx] derived from GEOS‑chem CTM model simulations. The derived estimates provide an observation based conclusion on the important role of regional anthropogenic emissions of NOx in summertime ozone photochemistry in the remote areas of Siberia.

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Wind Energy Assessment during High-Impact Winter Storms in Southwestern Europe

Atmosphere ◽

10.3390/atmos12040509 ◽

2021 ◽

Vol 12 (4) ◽

pp. 509

Author(s):

Ana Gonçalves ◽

Margarida L. R. Liberato ◽

Raquel Nieto

Keyword(s):

Wind Energy ◽

Power Law ◽

Energy Production ◽

Weather Conditions ◽

High Impact ◽

Energy Potential ◽

Energy Assessment ◽

Logarithmic Law ◽

Strong Winds ◽

Wind Resource

The electricity produced through renewable resources is dependent on the variability of weather conditions and, thus, on the availability of the resource, as is the case with wind energy. This study aims to assess the wind resource available and the wind energy potential (WEP) during the December months for the three years 2017, 2018, and 2019, in southwestern Europe, when several high-impact storms affected the region. Additionally, a comparison of Prandtl’s logarithmic law and Power-law equations for extrapolation of the vertical wind profile is performed for onshore conditions, to evaluate the differences in terms of energy production, with the use of different equations. To assess the effect of the strong winds associated with the storms, 10 m wind components are used, with a 6-hourly temporal resolution, for the December months over the southwestern Europe region (30° N–65° N; 40° W–25° E). Results are compared to the climatology (1981–2010) and show an increase of wind intensity of 1.86 m·s−1 in southwestern Europe during December 2019, and a decrease up to 2.72 m·s−1 in December 2018. WEP is calculated for the selected wind turbine, 4 MW E-126 EP3—ENERCON, as well as the values following the wind resource record, that is, (i) higher values in December 2019 in the offshore and onshore regions, reaching 35 MWh and 20 MWh per day, respectively, and (ii) lower values in December 2018, with 35 MWh and 15 MWh per day for offshore and onshore. Differences in WEP when using the two equations for extrapolation of wind vertical profile reached 60% (40%) in offshore (onshore) regions, except for the Alps, where differences of up to 80% were reached. An additional analysis was made to understand the influence of the coefficients of soil roughness and friction used in each equation (Prandtl’s logarithmic law and Power-law), for the different conditions of onshore and offshore. Finally, it is notable that the highest values of wind energy production occurred on the stormy days affecting southwestern Europe. Therefore, we conclude that these high-impact storms had a positive effect on the wind energy production in this region.

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The role of air density in wind energy assessment – A case study from Germany

Energy ◽

10.1016/j.energy.2019.01.041 ◽

2019 ◽

Vol 171 ◽

pp. 385-392 ◽

Cited By ~ 14

Author(s):

Christopher Jung ◽

Dirk Schindler

Keyword(s):

Wind Energy ◽

Energy Assessment ◽

Air Density

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Unravelling the Role of Socioeconomic Forces in the Early Stage of COVID-19 Pandemic: A Global Analysis

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18126340 ◽

2021 ◽

Vol 18 (12) ◽

pp. 6340

Author(s):

Kostas Rontos ◽

Maria-Eleni Syrmali ◽

Luca Salvati

Keyword(s):

Early Stage ◽

Global Analysis ◽

Healthcare Services ◽

Large Set ◽

Health Crisis ◽

Transmission Mechanisms ◽

Virus Dissemination ◽

Sustainable Health ◽

Background Context

The COVID-19 pandemic has rapidly evolved into an acute health crisis with extensive socioeconomic and demographic consequences. The severity of the COVID-19 pandemic requires a refined (and more comprehensive) understanding of virus dissemination over space, transmission mechanisms, clinical features, and risk factors. In line with this assumption, the present study illustrates a comparative, empirical analysis of the role of socioeconomic and demographic dimensions in the early stages of the COVID-19 pandemic grounded on a large set of indicators comparing the background context across a global sample of countries. Results indicate that—in addition to epidemiological factors—basic socioeconomic forces significantly shaped contagions as well as hospitalization and death rates across countries. As a response to the global crisis driven by the COVID-19 pandemic, all-embracing access to healthcare services should be strengthened along with the development of sustainable health systems supported by appropriate resources and skills. The empirical findings of this study have direct implications for the coordination of on-going, global efforts aimed at containing COVID-19 (and other, future) pandemics.

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Regional variation of recession flow power-law exponent

Hydrological Processes ◽

10.1002/hyp.11441 ◽

2018 ◽

Vol 32 (7) ◽

pp. 866-872 ◽

Cited By ~ 9

Author(s):

Swagat Patnaik ◽

Basudev Biswal ◽

Dasika Nagesh Kumar ◽

Bellie Sivakumar

Keyword(s):

Power Law ◽

Regional Variation ◽

Power Law Exponent ◽

Flow Power

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Growth Rate Exponents of Richtmyer-Meshkov Mixing Layers

Journal of Applied Mechanics ◽

10.1115/1.2164510 ◽

2005 ◽

Vol 73 (3) ◽

pp. 461-468 ◽

Cited By ~ 10

Author(s):

Timothy T. Clark ◽

Ye Zhou

Keyword(s):

Flow Field ◽

Power Law ◽

Mixing Layer ◽

Power Laws ◽

Mixing Layers ◽

Spatial Gradients ◽

Power Law Exponent ◽

Virtual Time ◽

Time Origin ◽

Density Ratios

The Richtmyer-Meshkov mixing layer is initiated by the passing of a shock over an interface between fluid of differing densities. The energy deposited during the shock passage undergoes a relaxation process during which the fluctuational energy in the flow field decays and the spatial gradients of the flow field decrease in time. This late stage of Richtmyer-Meshkov mixing layers is studied from the viewpoint of self-similarity. Analogies with weakly anisotropic turbulence suggest that both the bubble-side and spike-side widths of the mixing layer should evolve as power-laws in time, with the same power-law exponent and virtual time origin for both sides. The analogy also bounds the power-law exponent between 2∕7 and 1∕2. It is then shown that the assumption of identical power-law exponents for bubbles and spikes yields fits that are in good agreement with experiment at modest density ratios.

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Free Convective MHD Flow Past a Vertical Cone with Variable Heat and Mass Flux

Journal of Fluids ◽

10.1155/2013/405985 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

J. Prakash ◽

S. Gouse Mohiddin ◽

S. Vijaya Kumar Varma

Keyword(s):

Boundary Layer ◽

Power Law ◽

Mass Flux ◽

Numerical Study ◽

Convection Boundary Layer ◽

Vertical Cone ◽

Local Skin ◽

Surface Mass ◽

Flow Past ◽

Power Law Exponent

A numerical study of buoyancy-driven unsteady natural convection boundary layer flow past a vertical cone embedded in a non-Darcian isotropic porous regime with transverse magnetic field applied normal to the surface is considered. The heat and mass flux at the surface of the cone is modeled as a power law according to qwx=xm and qw*(x)=xm, respectively, where x denotes the coordinate along the slant face of the cone. Both Darcian drag and Forchheimer quadratic porous impedance are incorporated into the two-dimensional viscous flow model. The transient boundary layer equations are then nondimensionalized and solved by the Crank-Nicolson implicit difference method. The velocity, temperature, and concentration fields have been studied for the effect of Grashof number, Darcy number, Forchheimer number, Prandtl number, surface heat flux power-law exponent (m), surface mass flux power-law exponent (n), Schmidt number, buoyancy ratio parameter, and semivertical angle of the cone. Present results for selected variables for the purely fluid regime are compared with the published results and are found to be in excellent agreement. The local skin friction, Nusselt number, and Sherwood number are also analyzed graphically. The study finds important applications in geophysical heat transfer, industrial manufacturing processes, and hybrid solar energy systems.

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