The available power from placing tidal stream turbines in the Pentland Firth

This paper assesses an upper bound for the tidal stream power resource of the Pentland Firth. A depthaveraged numerical model of the tidal dynamics in the region is set-up and validated against field measurements. Actuator disc theory is used to model the effect of turbines on the flow, and to estimate the power available for generation after accounting for losses owing to mixing downstream of the turbines. It is found that three rows of turbines extending across the entire width of the Pentland Firth and blocking a large fraction of the channel can theoretically generate 1.9GW, averaged over the spring-neap cycle. However, generation of significantlymore power than this is unlikely to be feasible as the available power per additional swept area of turbine is too small to be viable. Our results differ from those obtained using simplified tidal channelmodels of the type used commonly in the literature.We also use our numerical model to investigate the available power from rows of turbines placed across various subchannels within the Pentland Firth, together with practical considerations such as the variation in power over the spring-neap tidal cycle and the changes to natural tidal flows which result from power extraction. © 2013 The Author(s) Published by the Royal Society. All rights reserved

Resource Characterization of Sites in the Vicinity of an Island near a Landmass

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Renewable energy technologies are undergoing rapid development, the global aim being to achieve energy security and lower carbon emissions. Of marine renewable energy sources, tidal power has inherent predictability and large theoretical potential, estimated to exceed 8000 (TW h)a−1 in coastal basins. Coastal sites in the vicinity of an island near a landmass are prime candidates for tidal stream power exploitation by arrays of turbines. This paper characterizes numerically the upper limit to power extraction of turbines installed at such sites. It is demonstrated that the maximum power extracted from the strait is generally not well approximated by either the power dissipated naturally at the seabed or the undisturbed kinetic power of flow in the strait. An analytical channel model [C. Garrett and P. Cummins, “The power potential of tidal currents in channels,” Proc. R. Soc. A Math. Phys. Eng. Sci., vol. 461, no. 2060, pp. 2563–2572, Aug. 2005] provides lower predictions than the present numerical model of available power in the strait due to the analytical model not accounting for changes to the driving head resulting from power extraction and flow diversion offshore of the island. For geometrically long islands extending parallel to the landmass, the numerically predicted extracted power is satisfactorily approximated by the power naturally dissipated at the seabed, and there is reasonable agreement with the estimate by the channel analytical model. It is found that the results are sensitive to choice of boundary conditions used for the coastlines, the eddy viscosity, and bed friction. Increased offshore depth and lower blockage both reduce the maximum power extracted from the strait. The results indicate that power extracted from the site can be maximum if extraction is implemented both in the strait and offshore of the island. Presence of the landmass and increasing island dimensions both enhance power extraction.This work was supported by General Electric Renewable Energy with funding from the ETI and the EPSRC through the Industrial Doctoral Centre for Offshore Renewable Energy (EP/J500847/1). The authors would like to thank the Applied Modelling and Computation Group at Imperial College of London for free access to the software Fluidity and their support

Modelling 3D hydrodynamics governing island-associated sandbanks in a proposed tidal stream energy site

© 2017 The Authors A 3D numerical modelling study to investigate the existing hydrodynamic regime of the Pentland Firth Inner Sound Channel, Scotland, UK is presented. Hydrodynamics that govern some sensitive sedimentary deposits in the Inner Sound Channel are discussed. A 3D hydrodynamic model Delft3D is set up for Pentland Firth, located between Orkney Islands and mainland Scotland and a full sensitivity analysis of the numerical model is carried out. The current model set up sufficiently captures the existing hydrodynamics during a full spring-neap tidal cycle inside Pentland Firth. Using model results, the 3D structure of the dynamics of the tidal flows in the Inner Sound Channel is investigated. The temporal variability of tidal flows, the residual tidal flows in the channel and local flow interactions with the Island of Stroma are described. It is proved that the tidally dominant flows drive the sediment transport gradient model to explain the principle maintenance mechanisms of two island-associated sandbanks present in the Inner Sound. The present study provides detailed information on the physics of the tidal regime in the Inner Sound and explains the presence of sandbanks in an area of high tidal flows. Due to extremely high tidal flows, Inner Sound is considered as one of the most favourable sites for tidal energy extraction in the UK. The findings of this study will be very useful in assessing the significance of impacts of future tidal energy extraction on natural hydrodynamics and sediment dynamics of the area

Unstructured grid modelling of offshore wind farm impacts on seasonally stratified shelf seas

Shelf seas comprise approximately 7% of the world’s oceans and host enormous economic activity. Development of energy installations (e.g. Offshore Wind Farms (OWFs), tidal turbines) in response to increased demand for renewable energy requires a careful analysis of potential impacts. Recent remote sensing observations have identified kilometrescale impacts from OWFs. Existing modelling evaluating monopile impacts has fallen into two camps: small-scale models with individually resolved turbines looking at local effects; and large-scale analyses but with sub-grid scale turbine parameterisations. This work straddles both scales through a 3D unstructured grid model (FVCOM): wind turbine monopiles in the eastern Irish Sea are explicitly described in the grid whilst the overall grid domain covers the south-western UK shelf. Localised regions of decreased velocity extend up to 250 times the monopile diameter away from the monopile. Shelf-wide, the amplitude of the M2 tidal constituent increases by up to 7%. The turbines enhance localised vertical mixing which decreases seasonal stratification. The spatial extent of this extends well beyond the turbines into the surrounding seas. With significant expansion of OWFs on continental shelves, this work highlights the importance of how OWFs may impact coastal (e.g. increased flooding risk) and offshore (e.g. stratification and nutrient cycling) areas

Yapay sinir ağlarının teknik analizde kullanımı ve bir uygulama

ARTIFICIAL NEURAL NETWORKS IN TECHNICAL ANALYSIS AND APPLICATION With the recent improvements in science and technology new tools in decision making have emerged. Artificial neural networks are one of them. The areas in which we can use artificial neural networks vary from financial forecasting to speech recognition. The employment of artificial neural networks in technical analysis in order to make some buy or sell decision about the selected stock is one of these areas. The purpose of this study is to examine the potentiality of artificial neural networks in stock trading. In order to examine this issue, first we will give some introductory information about the artificial neural networks and then try to make an application. APLICATION In the application 3 stocks from IMKB 30 list were randomly selected and 2 month's data from each of the stock were gathered. The intention is to foresee the possible price movements for the next session by using the past data belong to the previous session. Input values are the lowest, the highest, and the closing price of the stock, 7 session moving average value and finally the percentage value of the number of the stocks, which have higher closing price figure. For the training of the model, data from the 10 sessions are used. At the end of the 11th session the new input values are introduced to the model to make some predictions about the 12th session. The results of the model can be seen in both tabular and graphic form at the end of the thesis. Decision rules can also be seen in tabular form in the "conclusion" section. YAPAY SİNİR AĞLARININ TEKNİK ANALİZDE KULLANIMI VE BİR UYGULAMA Özellikle son zamanlarda bilimin her alanında ve özellikle bilgisayar teknolojisi alnındaki gelişmeler yeni karar verme tekniklerini insan oğlunun hizmetine sunmaktadır. Yapay sinir ağları bu tip yeni karar verme tekniklerinden biridir. Yapay sinir ağları birçok alanda karar verme sürecine yardımcı araç olarak kullanılabilmektedir. Hisse senedine ait alım, satım ve elde tutma kararlarının verilmesi yapay sinir ağlarının kullanılabileceği bu tip alanlardan biridir. Bu çalışmanın amacı yapay sinir ağlarının borsada alım-satım veya bekleme kararlarının verilmesinde ne şekilde kullanılabileceğinin incelenmesinden ibarettir. Bu amaçla öncelikle yapay sinir ağlarının tanımı, çalışma prensipleri, tipleri, üstün ve zayıf yönleri incelendikten sonra konu ile ilgili bir uygulama yapılmaya çalışılacaktır. UYGULAMA Tezin uygulama kısmında IMKB 30'a kayıtlı olan 3 senet rastgele olarak belirlenmiş ve bu senetlere ait iki aylık verileri kapsayan bir uygulama yapılmıştır. Uygulamada oluşturulan çok kademeli bir sinir ağı ile hisselere ait muhtemel fiyat değişiklikleri bir sonraki seans için öngörülmeye çalışılacaktır. Kullanılan sinir ağının eğitimi için "gözetmenli öğrenme" algoritması seçilmiştir. Girdi değişkenleri olarak hisseye ait seanslık fiyat değişim değerleri, 7 seanslık basit haraketli ortalama ile ilgili seansta yükselen hisse sayısının yüzdesini gösteren değer kullanılacaktır. Sinir ağı 10 seansa ait eğitim kümesi ile eğitilmektedir. Uygulama sonuçları "excel" programı kullanılarak tablolaştırılmıştır. Bu tablolarda bilgisayar programına ait hesaplanan değerler ile alım-satım veya elde tutma kararları gösterilmektedir. Ayrıca model tarafından üretilen kararların daha iyi görülebilmesi ve model performansının görsel olarak daha iyi ölçülebilmesi amacıyla mevcut kararlar belirlenen süreyi kapsayacak şekilde her bir senet için hazırlanan fiyat grafikleri üzerinde işaretlenmeye çalışılmıştır

The sensitivity of tidal resonance in the Bristol Channel

The energy resource in the Bristol Channel is of national strategic significance to meet the future demand for low carbon energy, and is the single largest resource area for tidal energy in the UK. However, the complex tidal dynamics of the Bristol Channel are not yet fully understood, in particular the sensitivity of the tidal dynamics to changes such as those caused by energy extraction. This is the motivation for the development of a simplified two-dimensional model to simulate the tidal flows in Bristol Channel. The tidal resonance in Bristol Channel has been investigated by exciting the model with a single tidal component and a series of sensitivity tests have been carried out on tuneable model parameters

The sensitivity of tidal resonance in the Bristol Channel

The energy resource in the Bristol Channel is of national strategic significance to meet the future demand for low carbon energy, and is the single largest resource area for tidal energy in the UK. However, the complex tidal dynamics of the Bristol Channel are not yet fully understood, in particular the sensitivity of the tidal dynamics to changes such as those caused by energy extraction. This is the motivation for the development of a simplified two-dimensional model to simulate the tidal flows in Bristol Channel. The tidal resonance in Bristol Channel has been investigated by exciting the model with a single tidal component and a series of sensitivity tests have been carried out on tuneable model parameters