Energy Conversion OWC Devices With Additional Vertical Ducts

2008 ◽  
Author(s):  
Sergio M. Camporeale ◽  
Pasquale G. F. Filianoti
Keyword(s):  
Energy Conversion ◽  
Large Fraction ◽  
Scale Model ◽  
Small Scale ◽  
Wells Turbine ◽  
Small Opening ◽  
North East ◽  
The North ◽  
Pneumatic Power ◽  
Vertical Duct

In breakwaters embodying an OWC connected to the sea through a vertical duct or through a small opening, the oscillations of the water column are due to the wave pressure acting on the outer opening of the vertical duct or on the small opening. In fact, in neither of the two cases waves can enter the plant, like it happens in conventional OWCs. The additional vertical duct extends along the wave-beaten wall, giving the device the characteristic form of a U-conduit; for this reason they were also named U-OWC. Experiments on a small-scale breakwater embodying a U-OWC were carried out in the natural laboratory of Reggio Calabria. The plant is a 1:10 scale model of a breakwater suitable for the North-East Pacific coast. The paper describes new experiments on the U-OWC device connected to a monoplane Wells turbine. During an intensive measurement campaign, more than 260 sea states, 5 min long were recorded in order to characterize the energy conversion process. From the experiments, the analysis of the energy conversion shows that: 1) the system is able to absorb a share up 80% of the incident wave energy; this result is similar to that obtained in previous experiments carried out without the turbine; 2) a large fraction of the energy entering the U-OWC is converted in pneumatic power acting on the turbine, being head losses in the water flow limited; 3) the efficiency of conversion of the pneumatic power in turbine power is relatively low (about 36% of the pneumatic power) due to the small dimensions of the turbine that lead to low Reynolds number and large influence of secondary losses.

Excavations at Verulamium, 1961. Seventh and Final Interim Report

1962 ◽  
Vol 42 (2) ◽  
pp. 148-159 ◽  
Author(s):  
S. S. Frere
Keyword(s):  
Small Scale ◽  
Natural Soil ◽  
Masonry Building ◽  
Interim Report ◽  
The West ◽  
North East ◽  
The North

Two small-scale excavations were carried out at Verulamium during 1961. In January it became necessary to explore the site about to be occupied by the museum extension, and several trenches were cut on the north-east and south-east sides of the existing museum building. It was not possible in the time and with the resources available to excavate down to natural soil, but only to examine those layers due for removal by the builders. Considerable depths of deposit are known to exist here, possibly filling an early ditch. The site lies in the west corner of Insula XVIII: the earliest structure reached was a timber-framed building, burnt down possibly c. A.D. 155. This was succeeded by an Antonine masonry building with channel hypocausts. Possibly c. A.D. 300 this building was enlarged by encroachment on the street frontages. It clearly extends some way outside the area excavated both towards east and south. The character of the structure is domestic.

scholarly journals Transversely isotropic lower crust of Variscan central Europe imaged by ambient noise tomography of the Bohemian Massif

Solid Earth ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 1051-1074
Author(s):  
Jiří Kvapil ◽  
Jaroslava Plomerová ◽  
Hana Kampfová Exnerová ◽  
Vladislav Babuška ◽  
György Hetényi ◽  
...  
Keyword(s):  
Bohemian Massif ◽  
Lower Crust ◽  
Ambient Noise ◽  
Regional Scale ◽  
Crustal Thickening ◽  
Scale Model ◽  
Significant Feature ◽  
Ambient Noise Tomography ◽  
North East ◽  
The North

Abstract. The recent development of ambient noise tomography, in combination with the increasing number of permanent seismic stations and dense networks of temporary stations operated during passive seismic experiments, provides a unique opportunity to build the first high-resolution 3-D shear wave velocity (vS) model of the entire crust of the Bohemian Massif (BM). This paper provides a regional-scale model of velocity distribution in the BM crust. The velocity model with a cell size of 22 km is built using a conventional two-step inversion approach from Rayleigh wave group velocity dispersion curves measured at more than 400 stations. The shear velocities within the upper crust of the BM are ∼0.2 km s−1 higher than those in its surroundings. The highest crustal velocities appear in its southern part, the Moldanubian unit. The Cadomian part of the region has a thinner crust, whereas the crust assembled, or tectonically transformed in the Variscan period, is thicker. The sharp Moho discontinuity preserves traces of its dynamic development expressed in remnants of Variscan subductions imprinted in bands of crustal thickening. A significant feature of the presented model is the velocity-drop interface (VDI) modelled in the lower part of the crust. We explain this feature by the anisotropic fabric of the lower crust, which is characterised as vertical transverse isotropy with the low velocity being the symmetry axis. The VDI is often interrupted around the boundaries of the crustal units, usually above locally increased velocities in the lowermost crust. Due to the north-west–south-east shortening of the crust and the late-Variscan strike-slip movements along the north-east–south-west oriented sutures preserved in the BM lithosphere, the anisotropic fabric of the lower crust was partly or fully erased along the boundaries of original microplates. These weakened zones accompanied by a velocity increase above the Moho (which indicate an emplacement of mantle rocks into the lower crust) can represent channels through which portions of subducted and later molten rocks have percolated upwards providing magma to subsequently form granitoid plutons.

scholarly journals The Wave-to-Wire Energy Conversion Process for a Fixed U-OWC Device

Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 283 ◽  
Author(s):  
Luana Gurnari ◽  
Pasquale G. F. Filianoti ◽  
Marco Torresi ◽  
Sergio M. Camporeale
Keyword(s):  
Energy Conversion ◽  
Power Output ◽  
Fluid Dynamic ◽  
Conversion Process ◽  
Oscillating Flow ◽  
Wave Power ◽  
Wells Turbine ◽  
Air Chamber ◽  
Energy Conversion Process ◽  
Pneumatic Power

Oscillating water column (OWC) devices, either fixed or floating, are the most common wave energy converter (WEC) devices. In this work, the fluid dynamic interaction between waves and a U-shaped OWC breakwater embedding a Wells turbine has been investigated through unsteady Computational Fluid Dynamic (CFD) simulations. The full-scale plant installed in the harbor of Civitavecchia (Italy) was numerically modeled. A two-dimensional domain was adopted to simulate the unsteady flow, both outside and inside the U-OWC device, including the air chamber and the oscillating flow inside the conduit hosting the Wells turbine. For the numerical simulation of the damping effect induced by the Wells turbine connected to the air chamber, a porous medium was placed in the computational domain, representing the conduit hosting the turbine. Several simulations were carried out considering periodic waves with different periods and amplitudes, getting a deep insight into the energy conversion process from wave to the turbine power output. For this purpose, the three main steps of the overall energy conversion process have been examined. Firstly, from the wave power to the power of the water oscillating flow inside the U-duct. Secondly, from the power of the oscillating water flow to the air pneumatic power. Finally, from the air pneumatic power to the Wells turbine power output. Results show that the U-OWC can capture up to 66% of the incoming wave power, in the case of a wave period close to the eigenperiod of the plant. However, only two-thirds of the captured energy flux is available to the turbine, being partially dissipated due to the losses in the U-duct and the air chamber. Finally, the overall time-average turbine power output is evaluated showing that it is strongly influenced by a suitable choice of the turbine characteristics (mainly geometry and rotational speed).

scholarly journals "Scale oriented" embedded modeling of the North-Western Mediterranean in the frame of MFSTEP

Ocean Science ◽  
2009 ◽  
Vol 5 (2) ◽  
pp. 73-90 ◽  
Author(s):  
C. Estournel ◽  
F. Auclair ◽  
M. Lux ◽  
C. Nguyen ◽  
P. Marsaleix
Keyword(s):  
Weather Prediction ◽  
Regional Model ◽  
Western Mediterranean ◽  
Scale Model ◽  
Small Scale ◽  
Surface Model ◽  
Strong Wind ◽  
The North ◽  
Gulf Of Lion ◽  
North Western

Abstract. An embedded forecasting system was developed for the North-Western Mediterranean at 3-km resolution. The system is based on the Symphonie hydrodynamic free surface model and on the variational initialization and forcing platform VIFOP. The regional model is initialized and forced at its open lateral boundaries by the MFS GCM and forced at the surface by the ALADIN numerical weather prediction model. Once a week, a five-day forecast is produced after a hindcast of seven days. This pre-modeling period of 7 days before beginning the forecast allows the development of the small scale features associated to the high resolution. The relevance of the 5-day forecast strategy has been examined by comparing the forecasted fields to hindcast fields (forced by meteorological and oceanic analyses) considered as a reference. Mismatches remain at a very low level indicating a good quality of the forecasted forcing fields and also possibly to the strong wind conditions which prevailed during the period. The embedded forecasts have been compared to the MFS observing system (SST and MedArgo) during 6 forecast cycles between September 2004 and February 2005. It was basically found that in the North-Western Mediterranean, the MFS basin-scale model and thus the regional model forecasts are characterized by large negative biases of salinity in the first 100 m under the surface leading thus to too light subsurface waters. The underestimation of temperature by the regional model just below the surface and its overestimation at 30m deep can be attributed to an overestimation of the turbulent mixing. The regional model allows to represent a number of processes especially those induced by the wind as coastal upwelling under stratified conditions, dense water formation over the Gulf of Lion shelf, deep mixing in the convection zone or influence on the Northern Current penetration in the Gulf of Lion.

scholarly journals Economic Impact of Eliminating the Fuel Tax Exemption in the EU Fishing Fleet

2021 ◽  
Vol 13 (5) ◽  
pp. 2719
Author(s):  
Natacha Carvalho ◽  
Jordi Guillen
Keyword(s):  
Large Scale ◽  
Small Scale ◽  
Fuel Price ◽  
Socioeconomic Impacts ◽  
Fuel Tax ◽  
Fishing Fleet ◽  
North East ◽  
The North ◽  
Fishing Fleets ◽  
The Eu

The EU-27 fishing fleet consumed 2.02 billion liters of fuel to catch 4.48 million tons of fish, valued at €6.7 billion in 2018. The profitability of the EU fishing fleet shows an increasing trend, partly due to the improvements in the energy efficiency and recovery of fish stocks in the North-east Atlantic. Fuel is one of the main expenses fishing fleets have, and therefore, their economic performance remains highly dependent on the fuel price, even if they benefit from a fuel tax exemption. The adoption of the European Green Deal, the revision of the Energy Taxation Directive (ETD), the ongoing World Trade Organization (WTO) negotiation to prohibit harmful fisheries subsidies, and general public opinion are putting pressure to eliminate this tax exemption. This analysis investigates the impacts of the potential elimination of the fuel tax exemption across the different EU fishing fleets and it is discussed to what extent the small-scale, large-scale and distant-water fleets could be affected. This analysis is useful to inform policy-makers and stakeholders on the consequences of the potential elimination of the fuel tax exemption, as well as to discuss potential measures to mitigate the socioeconomic impacts arising from this eventual change in the current regulatory framework.

The Marlborough Mound, Wiltshire. A Further Neolithic Monumental Mound by the River Kennet

2013 ◽  
Vol 79 ◽  
pp. 137-163 ◽  
Author(s):  
Jim Leary ◽  
Matthew Canti ◽  
David Field ◽  
Peter Fowler ◽  
Peter Marshall ◽  
...  
Keyword(s):  
Future Research ◽  
Small Scale ◽  
Main Body ◽  
Soil Cores ◽  
Flood Events ◽  
The South ◽  
Late Neolithic ◽  
Radiocarbon Dates ◽  
North East ◽  
The North

Recent radiocarbon dates obtained from two soil cores taken through the Marlborough Castle mound, Wiltshire, show the main body of it to be a contemporaneous monument to Silbury Hill, dating to the second half of the 3rd millennium cal bc. In light of these dates, this paper considers the sequence identified within the cores, which includes two possible flood events early in the construction of the mound. It also describes four cores taken through the surrounding ditch, as well as small-scale work to the north-east of the mound. The topographic location of the mound in a low-lying area and close to rivers and springs is discussed, and the potential for Late Neolithic sites nearby is set out, with the land to the south of the mound identified as an area for future research. The paper ends with the prospect that other apparent mottes in Wiltshire and beyond may well also have prehistoric origins

scholarly journals Local Geographies of Digital Inequality

2017 ◽  
Vol 36 (1) ◽  
pp. 82-102 ◽  
Author(s):  
Grant Blank ◽  
Mark Graham ◽  
Claudio Calvino
Keyword(s):  
Internet Use ◽  
Policy Implications ◽  
Internet Survey ◽  
Sample Survey ◽  
Small Scale ◽  
Digital Inequality ◽  
North East ◽  
The North ◽  
Combining Data ◽  
Geographic Differences

Combining data from a sample survey, the 2013 Oxford Internet Survey, with the 2011 UK Census, we employ small area estimation to estimate Internet use in small geographies in Britain. This is the first attempt to estimate Internet use at any small-scale level. Doing so allows us to understand the local geographies of British Internet use, showing that the area with least use is in the North East, followed by central Wales. The highest Internet use is in London and southeastern England. The most interesting finding is that after controlling for demographic variables, geographic differences become nonsignificant. The apparent geographic differences appear to be due to differences in demographic characteristics. We conclude by considering the policy implications of this fact.

scholarly journals Atmospheric histories and emissions of chlorofluorocarbons CFC-13(CClF<sub>3</sub>), CFC-114 (C<sub>2</sub>Cl<sub>2</sub>F<sub>4</sub>), and CFC-115 (C<sub>2</sub>ClF<sub>5</sub>)

2017 ◽  
Author(s):  
Martin K. Vollmer ◽  
Dickon Young ◽  
Cathy M. Trudinger ◽  
Jens Mühle ◽  
Stephan Henne ◽  
...  
Keyword(s):  
Mole Fraction ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Global Analysis ◽  
Large Fraction ◽  
Ambient Air ◽  
North East ◽  
The North ◽  
High Level ◽  
Global Emissions

Abstract. Based on observations of three chlorofluorocarbons, CFC-13 (chlorotrifluoromethane), CFC-114 (dichlorotetrafluoroethane) and CFC-115 (chloropentafluoroethane) in atmospheric and firn samples, we reconstruct records of their tropospheric histories spanning nearly eight decades. These compounds were measured in polar firn air samples, in ambient air archived in canisters, and in-situ at the AGAGE (Advanced Global Atmospheric Gases Experiment) network and affiliated sites. Global emissions to the atmosphere are derived from these observations using an inversion based on a 12-box atmospheric transport model. For CFC-13, we provide the first comprehensive global analysis. This compound increased monotonically from its first appearance in the atmosphere in the late 1950s to a mean global abundance of 3.18 ppt (dry air mole fraction in parts-per-trillion, pmol mol−-1) in 2016. Its growth rate has decreased since the mid 1980s but has remained at a surprisingly high level of 0.02 ppt yr−1 since the late 2000s. CFC-114 increased from its appearance in the 1950s to a maximum of 16.6 ppt in the early 2000s, and has since slightly declined to 16.3 ppt in 2016. CFC-115 increased monotonically from its first appearance in the 1960s and reached a global mean mole fraction of 8.52 ppt in 2016. Growth rates of all three compounds over the past years are significantly larger than would be expected from zero emissions. Under the assumption of unaltered lifetimes and atmospheric transport patterns, we derive global emissions from our measurements, which have remained unexpectedly high in recent years: Mean yearly emissions for the last decade (2007–2016) of CFC-13 are at 0.48 ± 0.15 kt yr−1 (> 15 % of past peak emissions), of CFC-114 at 1.90 ± 0.84 kt yr−1 (~ 10 % of peak emissions), and of CFC-115 at 0.80 ± 0.50 kt yr−1 (> 5 % of peak emissions). Mean yearly emissions of CFC-115 for 2014–2016 are 1.08 ± 0.50 kt yr−1 and have more than doubled compared to 2009. Cumulative global emissions for CFC-114 derived from observations through 2016 exceed the global cumulative production derived from reported inventory data by > 10 % while those for CFC-115 agree well. We find CFC-13 emissions from aluminum smelters and impurities of CFC-115 in the refrigerant HFC-125 (CHF2CF3) but if extrapolated to global emissions neither of them can account for the lingering global emissions determined from the atmospheric observations. We also conduct regional inversions for the years 2012–2016 for the north-east Asian area using observations from the Korean Gosan AGAGE site and find significant emissions for CFC-114 and CFC-115, suggesting that a large fraction of their global emissions currently occur in north-eastern Asia and more specifically on the Chinese mainland.

Reinforced Ice and Ice Domes: Opportunities for the North*

1988 ◽  
Vol 3 (2) ◽  
pp. 84-102 ◽  
Author(s):  
P.G. Glockner
Keyword(s):  
Tensile Strength ◽  
Scale Model ◽  
Small Scale ◽  
Construction Technique ◽  
The North ◽  
Pull Out ◽  
Initiation And Propagation ◽  
University Of Calgary ◽  
The University ◽  
Small Scale Model

It is suggested that reinforced ice domes in spans up to 100–150 metres and constructed by spraying water onto a spherical inflatable membrane could be economic solutions for constructing temporary enclosures in cold regions. The feasibility and practicability of such a novel and economical erection/construction technique has been demonstrated at The University of Calgary by constructing small-scale model ice domes and testing them until failure. Details of this erection technique, properties of the reinforcement (spun fibreglass yarn) and the load-deflection-time behaviour of the model domes are described. The first part of the paper gives some results on the short-duration load and creep response of unreinforced and reinforced ice samples, including shear. pull-out/bond and tensile strength. The results indicate that such fibreglass yarn reinforcement does not enhance the shear strength of ice but does inhibit initiation and propagation of cracking and thereby increase the ultimate tensile strength of the composite.

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