scholarly journals Influence of tidal parameters on SeaGen flicker performance

2013 ◽  
Vol 371 (1985) ◽  
pp. 20120247 ◽  
Author(s):  
Joseph MacEnri ◽  
Matthew Reed ◽  
Torbjörn Thiringer
Keyword(s):  
Water Depth ◽  
Strong Relationship ◽  
Tidal Energy ◽  
Graphical Analysis ◽  
Measured Data ◽  
Energy Converter ◽  
Testing Period ◽  
Set Up

This paper presents the analysis of the study of the flicker emitted from the 1.2 MW tidal energy converter (TEC), SeaGen, against varying tidal parameters. This paper outlines the main elements of the TEC itself, the environment it is located in and the measurement set up. In this paper, the flicker emitted by the TEC is compared with the different tidal parameters, including flood and ebb tides, tidal speed, water depth and turbulence strength and intensity. Flicker emissions have been calculated from measured data in over 90 measurement (10 min) periods, and all of the tidal parameters vary significantly over that testing period. This allows for a detailed statistical and graphical analysis of the variation of flicker with the variation of the tidal parameters outlined above. It is found, with the exception of tidal speed, that there is no strong relationship between flicker emissions and any other tidal parameter. As SeaGen is an asymmetrical TEC with full blade pitching for flood and ebb generation, it was also found that the expected difference of flicker emissions owing to the effect of the submersed crossbeam was not significant. The TEC harmonic performance versus tidal speed is also presented.

scholarly journals Attenuation of Wave Energy Due to Mangrove Vegetation off Mumbai, India

Energies ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 4286 ◽  
Author(s):  
Samiksha S. V. ◽  
P. Vethamony ◽  
Prasad K. Bhaskaran ◽  
P. Pednekar ◽  
M. Jishad ◽  
...  
Keyword(s):  
Climate Change ◽  
Drag Coefficient ◽  
Wave Energy ◽  
Measured Data ◽  
Stem Diameter ◽  
Coastal Hazards ◽  
Sensitivity Analyses ◽  
Vegetation Density ◽  
Mangrove Vegetation ◽  
Set Up

Coastal regions of India are prone to sea level rise, cyclones, storm surges, and human-induced activities, resulting in flood, erosion, and inundation, and some of these impacts could be attributed to climate change. Mangroves play a very protective role against some of these coastal hazards. The primary aim of the study was to estimate wave energy attenuation by mangrove vegetation using modeling, and to validate the model results with measurements conducted off Mumbai coast, where a mangrove forest is present. Wave measurements were carried out from 5–8 August 2015 at three locations in a transect normal to the coast using surface-mounted pressure-level sensors in spring tide conditions. The measured data presented wave height attenuation of the order of 52%. Model set-up and sensitivity analyses were conducted to understand the model performance with respect to vegetation parameters. It was observed that wave attenuation increases with an increase in drag coefficient, vegetation density, and stem diameter. For a typical set-up in the Mumbai coastal region having a vegetation density of 0.175 per m2, stem diameter of 0.3 m, and drag coefficient varying from 0.4 to 1.5, the model reproduced attenuation ranging from 49% to 55%, which matches reasonably well with the measured data. Spectral analysis performed for the cases with and without vegetation very clearly portrays energy dissipation in the vegetation area. This study also highlights the importance of climate change and mangrove vegetation.

Research on the Pollution Diffusion Regularity near Sewage Outlet Areas in Yuncheng Reach of the Fen River

2011 ◽  
Vol 383-390 ◽  
pp. 2430-2436
Author(s):  
Jian Hua Hou ◽  
Min Quan Feng ◽  
Xiao Peng Xing ◽  
Zhen Hua Hou
Keyword(s):  
Water Quality ◽  
Flow Field ◽  
Water Depth ◽  
Concentration Gradient ◽  
River Flow ◽  
Measured Data ◽  
Quality Model

The purpose of this paper is to find the pollution diffusion regularity near sewage outlet area of Yuncheng reach of the Fen River. A 2-D water hydrodynamic and quality model was used to simulate flow field, the water quality and contamination dispersion. The parameters of the model were calibrated with measured data of the water depth, flow and water quality in Yuncheng reach of the Fen River. According to the simulated result, the total area of pollution belt with 19 sewage outlets is 8.89km2 in normal year. And 3.89% of the reach has a worse water quality than V class in standard. The percentage of V and Ⅳ Class of water is 69.17% and 26.94%.In dry year, the total area of pollution belt with 19 sewage outlets is 8.89km2.The percentage of inferior V, V and Ⅳ Class of water is 27.80%, 69.46% and 2.74%. It was shown by the simulated results that the concentration gradient decreases with increasing distance to the outlets and the dilution and dispersion of pollutants was enhanced by a greater river flow.

scholarly journals Wave energy dissipation in the mangrove vegetation off Mumbai, India

2017 ◽  
Author(s):  
Samiksha S. Volvaiker ◽  
Ponnumony Vethamony ◽  
Prasad K. Bhaskaran ◽  
Premanand Pednekar ◽  
MHamsa Jishad ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Drag Coefficient ◽  
Wave Height ◽  
Wave Attenuation ◽  
Coastal Region ◽  
Measured Data ◽  
Vegetation Density ◽  
Mangrove Vegetation ◽  
Wave Height Attenuation ◽  
Set Up

Abstract. Coastal regions of India are prone to sea level rise, cyclones, storm surges and human induced activities, resulting in flood, erosion, and inundation. The primary aim of the study is to estimate wave attenuation by mangrove vegetation using SWAN model in standalone mode, as well as SWAN nested with WW3 model for the Mumbai coastal region. To substantiate the model results, wave measurements were carried out during 5–8 August 2015 at 3 locations in a transect normal to the coast using surface mounted pressure level sensors under spring tide conditions. The measured data presents wave height attenuation of the order of 52 %. The study shows a linear relationship between wave height attenuation and gradual changes in water level in the nearshore region, in phase with the tides. Model set-up and sensitivity analyses were conducted to understand the model performance to vegetation parameters. It was observed that wave attenuation increased with an increase in drag coefficient (Cd), vegetation density, and stem diameter. For a typical set-up for Mumbai coastal region having vegetation density of 0.175 per m2, stem diameter of 0.3 m and drag coefficient varying from 0.4 to 1.5, the model reproduced attenuation, ranging from 49 to 55 %, which matches well with the measured data. Spectral analysis performed for the cases with and without vegetation very clearly portrays energy dissipation in the vegetation area as well as spectral changes. This study has the potential of improving the quality of wave prediction in vegetation areas, especially during monsoon season and extreme weather events.

An Experimental Study of Shallow Water Wave Statistics on Mild Bed Slopes

2011 ◽  
Author(s):  
Vasiliki Katsardi ◽  
Chris Swan
Keyword(s):  
Water Depth ◽  
Measured Data ◽  
Intermediate Water ◽  
Statistical Distributions ◽  
Spectral Bandwidth ◽  
Peak Period ◽  
Wave Statistics ◽  
Wave Heights ◽  
Bed Slope ◽  
Water Depths

This paper describes a new series of laboratory observations, undertaken in a purpose built wave flume, in which a number of scaled simulations of realistic ocean spectra were allowed to evolve over a range of mild bed slopes. The purpose of the study was to examine the distribution of wave heights and its dependence on the local water depth, d, the local bed slope, m, and the nature of the input spectrum; the latter considering variations in the spectral peak period, Tp, the spectral bandwidth and the wave steepness. The results of the study show that for mild bed slopes the statistical distributions of wave heights are effectively independent of both the bed slope and the spectral bandwidth. However, the peak period plays a very significant role in the sense that it alters the effective water depth. Following detailed comparisons with the measured data, the statistical distributions for wave heights in relatively deep water are found to be in reasonable agreement with the Forristall [1] and Glukhovskii [2] distributions. For intermediate water depths, the Battjes & Groenendijk [3] distribution works very well. However, for the shallowest water depths none of the existing distributions provides good agreement with the measured data; all leading to an over-estimate of the largest wave heights.

scholarly journals DENSITY MANAGEMENT DIAGRAM FOR Eucalyptus grandis W. Hill. ex Maiden STANDS CONTROLLED BY DOMINANT HEIGHT

FLORESTA ◽  
2020 ◽  
Vol 51 (1) ◽  
pp. 240
Author(s):  
Gabriel Paes Marangon ◽  
Emanuel Arnoni Costa ◽  
César Augusto Guimarães Finger ◽  
Paulo Renato Schneider ◽  
Matheus Teixeira Martins
Keyword(s):  
Eucalyptus Grandis ◽  
Strong Relationship ◽  
Site Index ◽  
Graphical Analysis ◽  
Coefficient Of Determination ◽  
Permanent Plots ◽  
Volume Number ◽  
Dominant Height ◽  
Development Site ◽  
Relationship Of

Density management diagram for eucalyptus stands controlled by dominant height. The present study aimed to elaborate Density Management Diagrams (DMD) for Eucalyptus grandis W. Hill. ex Maiden stands including the dominant height. Data were obtained from permanent plots installed in the Centro Oriental Riograndense region and the Porto Alegre Metropolitan area, both located in the state of Rio Grande do Sul. The models to describe the relationships between average volume, number of trees per hectare, mean diameter, and dominant height were assessed by the statistical criteria of coefficient of determination (R²), standard error of the estimate in percentage (Syx%), and graphical analysis of residuals. The developed DMD allows for a better control of stocks in the management of stands due to the strong relationship of dominant height with stand development site and forest yield.Keywords: Growth, Site index, Forest regulation, Yield.

Coaction Analysis on Pile-Net-Cushion-Soil

2014 ◽  
Vol 580-583 ◽  
pp. 579-584
Author(s):  
Rui Fang Wang ◽  
Ke Yu Wang
Keyword(s):  
Finite Element ◽  
Literature Review ◽  
Measured Data ◽  
Composite Foundation ◽  
Analytic Calculation ◽  
Three Dimension ◽  
Interaction Coefficients ◽  
Flexibility Matrix ◽  
Analytic Methods ◽  
Set Up

In accordance of the principles of stress continuousness and displacement coordination, the interactions model of pile and pile, pile and soil are set up;Accoring to the symmetry of the models,1/4 of the models are extracted to set up three-dimension multipile composite foundation models.The flexibility matrix of the three reinforcements are modified to build a global flexibility matrix with the consideration of cushion's compression; Interaction coefficients of the analytic calculation are lower than those of the finite element when pile lengthen is diversity.The comparison between the on-site measured data from the literature review and results of the analytic calculation shows the settlements in the analytic calculation are smaller than those in the measured data, and the model measurements are very close to the curves from the analytic calculation. All these prove that the analytic methods proposed by this research are accurate and may function as a reference to engineering.

scholarly journals Risk Perception of COVID−19 Community Transmission among the Spanish Population

2020 ◽  
Vol 17 (23) ◽  
pp. 8967
Author(s):  
José Miguel Mansilla Domínguez ◽  
Isabel Font Jiménez ◽  
Angel Belzunegui Eraso ◽  
David Peña Otero ◽  
David Díaz Pérez ◽  
...  
Keyword(s):  
Risk Perception ◽  
Public Perception ◽  
Online Survey ◽  
Strong Relationship ◽  
Spanish Population ◽  
Prevention Measures ◽  
Perception Of Risk ◽  
Cross Sectional ◽  
Effective Prevention ◽  
Set Up

On 11 March 2020 the SARS-CoV−2 virus was officially declared a pandemic and measures were set up in various countries to avoid its spread among the population. This paper aims to analyse the perception of risk of COVID−19 infection in the Spanish population. A cross-sectional, descriptive observational study was conducted with a total of 16,372 Spanish participants. An online survey was used to gather data for 5 consecutive days over the compulsory lockdown period which was established after the state of emergency was declared. There is an association between socio-demographic variables and risk perception, and a very strong relationship between this perception and contact and direct experience with the virus in a family, social or professional setting. We also found that compared to working from home, working outside the home increased the perception of risk of infection and the perception of worsening health. Understanding the public perception of the risk of COVID−19 infection is fundamental for establishing effective prevention measures.

scholarly journals Performance and Wake Characterization of a Model Hydrokinetic Turbine: The Reference Model 1 (RM1) Dual Rotor Tidal Energy Converter

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 5145
Author(s):  
Craig Hill ◽  
Vincent S. Neary ◽  
Michele Guala ◽  
Fotis Sotiropoulos
Keyword(s):  
Reynolds Number ◽  
Reference Model ◽  
Angular Position ◽  
Tidal Energy ◽  
Wake Flow ◽  
Height Velocity ◽  
Scale Model ◽  
Speed Ratio ◽  
Power Performance ◽  
Energy Converter

The mechanical power and wake flow field of a 1:40 scale model of the US Department of Energy’s Reference Model 1 (RM1) dual rotor tidal energy converter are characterized in an open-channel flume to evaluate power performance and wake flow recovery. The NACA-63(4)-24 hydrofoil profile in the original RM1 design is replaced with a NACA-4415 profile to minimize the Reynolds dependency of lift and drag characteristics at the test chord Reynolds number. Precise blade angular position and torque measurements were synchronized with three acoustic Doppler velocimeters (ADV) aligned with each rotor centerline and the midpoint between the rotor axes. Flow conditions for each case were controlled to maintain a hub height velocity, uhub= 1.04 ms−1, a flow Reynolds number, ReD= 4.4 × 105, and a blade chord length Reynolds number, Rec= 3.1 × 105. Performance was measured for a range of tip-speed ratios by varying rotor angular velocity. Peak power coefficients, CP= 0.48 (right rotor) and CP= 0.43 (left rotor), were observed at a tip speed ratio, λ= 5.1. Vertical velocity profiles collected in the wake of each rotor between 1 and 10 rotor diameters are used to estimate the turbulent flow recovery in the wake, as well as the interaction of the counter-rotating rotor wakes. The observed performance characteristics of the dual rotor configuration in the present study are found to be similar to those for single rotor investigations in other studies. Similarities between dual and single rotor far-wake characteristics are also observed.

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