429 research outputs found
Replication Data for: 3D Shear‐wave Velocity and Density Modelling of the Northern Cascadia Subduction Zone
No full textDevelopment of 3D shear-wave velocity (Vs) and density models of southwest British Columbia and Washington State are accomplished as part of the Metro Vancouver Seismic Microzonation Project (MVSMMP) which aims to improve understanding of seismic hazards in the Georgia Basin.
The 3D Vs model is developed from ambient seismic noise and earthquake data recorded by temporary and permanent seismic stations in the last two decades. A 3D density model is also developed from a publicly available gravity dataset.
Here, we share a replication package that includes datasets (seismic and gravity), computer codes and scripts adopted and developed for this research work. The package also includes intermediate result files and final 3D models and GMT script used to plot each figure in the Ojo et al. (2025) JGR Solid Earth article. Our goal is to support research transparency and reproducibility of our work
Leading the African agenda or following the African consensus? South Africa's implementation of the African agenda in the United Nations Security Council
No full textReclaiming setbacks and open spaces for greening and sustainable landscape development in state capital cities: A case study of Ado-Ekiti, Nigeria.
No full textDoctoral degree. University of KwaZulu-Natal, Durban.The rapid rate of urbanization in developing countries generates various socio-economic and environmental challenges. In Nigerian urban centres, high rate of rural-urban drift aggravates population growth rate, and increasing space demand for land use and human activities put pressure on land resources. In Ado-Ekiti, Ekiti State capital, the study area, land is continuously fragmented, resulting to densely populated areas and inequitable use. This syndrome culminates in vegetal depletion, urban sprawl, environmental degradation and increasing poverty levels. Uncontrolled development, excessive hard landscaping and informal sector activities along transportation corridors, water bodies, utility lines, and the inner core areas deprive the city of adequate greenery. The research examines the city‘s spatial structure, socio-economic attributes of residents, setbacks and open space characteristics, pattern of encroachment, and the efficacy of development control legislations. The challenges posed by the inadequacy of greenery and excessive hard landscaping, government‘s effort in reclaiming lost spaces to create inclusive green areas for sustainable urban landscape were evaluated. The research methodology utilise relevant data from secondary sources to build literature and compliment socio-economic baseline data collected from primary sources by multi-stage technique across three morphological zones. Research findings expose devegetation, hardening, gross inadequacy and abuse of setbacks and air spaces, lack of organised open spaces and green areas. There is a disconnection between relatively high literacy level and contravention of development regulation laws. Informal development, mostly commercial, is rampant and driven by high poverty level and people‘s instinct to sustain their socio-economic needs. Ignorance of good quality environment, desire for economic benefits, and ineffective governmental control are other factors responsible for the disruption of public spaces. The study argued that the people engage in space contestation to survive, while the uncontrolled informal sector is neglected by government. Recommendations are hinged on the Strategic Urban Greening Intervention Model developed to encapsulate key systematic elements in the negative aspects, and how intervention strategies, tools and methods are deployed for positive transformation. Based on the Model, the proposed Ado-Ekiti Urban Greening Master Plan was prepared as policy directives and programmes for stakeholders‘ synergy to establish, monitor and maintain inclusive green areas in the city. Informal sector integration to strengthen livelihood strategy, inclusiveness and green economy is germane to
successful greening programme, failing which the people will return to the streets and continue to aggravate carbon footprints. Socio-economically, the research is guaranteed to diversify local economy, boost investment generation, and enhance living standards. Physical impacts include improved environmental quality, global warming abatement and climate change mitigation in the city. The Model developed out of this research and contribution promotes landscape sustainability in Ado-Ekiti and can be replicated in Africa cities
An exploration into the lower middle income housing market.
No full textThesis (M.Housing)-University of KwaZulu-Natal, Durban, 2009.The study explores the factors hampering the growth of a sustainable lower middle income (LMI) housing market. The LMI group includes members of the working class who earn between R3,500 and R7,000 per month. The motivation for the research followed an observation made in 2003, that the policies of both the Department of Housing and the traditional banking system excluded this income category from accessing housing assistance. However, during the course of the study, the state started extending subsidy assistance to this income group, through the Breaking New Ground (BNG) policy. The study employed oral and written data collection methods. The housing market participants was divided into three broad categories, namely, demand side participants, supply side participants and the housing market facilitators. Interviews were conducted with both supply side participants and facilitators. On the demand side a questionnaire survey was conducted to establish the experiences of households in respect of the home acquisition process. The research findings revealed that LMI households require a housing typology which is described as a two bedroom detached starter house, within close proximity to a public transport system, and other community facilities for ease of accessibility. The data showed that the LMI households required financial education before getting involved in the home acquisition transaction. In addition, it emerged that professional services offered by the estate agents were not being fully utilized by the LMI households simply because the households were not aware of the responsibility of the agents in the home acquisition transaction process. It is maintained that the LMI housing market is inundated with multi-faceted hurdles from both intrinsic and extrinsic sources. The intrinsic sources include household character, past experiences amongst others, while the extrinsic sources comprise housing stock availability, loan approval criteria, etc. These hurdles require both long and short term interventions addressing the convoluted home acquisition process which involves various facilitators and a costly immovable product. In conclusion, it is recommended that demand side home ownership education is necessary, whereby LMI households are prepared for the home acquisition process. On the supply side long and short term interventions are recommended towards creating enabling environments for the supply of starter houses located close to neighbourhood facilities particularly a reliable transport network
Parametric Curve Comparison for Modeling Floating Offshore Wind Turbine Substructures
No full textThe drive for the cost reduction of floating offshore wind turbine (FOWT) systems to the levels of fixed bottom foundation turbine systems can be achieved with creative design and analysis techniques of the platform with free-form curves to save numerical simulation time and minimize the mass of steel (cost of steel) required for design. This study aims to compare four parametric free-form curves (cubic spline, B-spline, Non-Uniform Rational B-Spline and cubic Hermite spline) within a design and optimization framework using the pattern search gradient free optimization algorithm to explore and select an optimal design from the design space. The best performance free-form curve within the framework is determined using the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). The TOPSIS technique shows the B-spline curve as the best performing free-form curve based on the selection criteria, amongst which are design and analysis computational time, estimated mass of platform and local shape control properties. This study shows that free-form curves like B-spline can be used to expedite the design, analysis and optimization of floating platforms and potentially advance the technology beyond the current level of fixed bottom foundations.Ship Design, Production and Operation
Geometric shape parameterization and optimization of floating offshore wind turbine substructure within an MDAO framework
No full textThe urgent need to reduce greenhouse gases to attain net zero emission and reverse climate change has put the world at a turning point to explore cleaner form of energy generation. This has spiked an increase in the offshore wind forms of energy generation and, most recently, a focus on the Floating Offshore Wind Turbine (FOWT) sector. However, despite the advantages of FOWT installations amongst which are; less environmental impact and accessibility to deeper waters for richer wind resources needed for significant power generation, the technology is presently still economically less viable in comparison to the fixed bottom foundation counterpart. Several research studies, aimed at ensuring the economic feasibility of FOWT have been performed, such as floating foundation upscaling, surrogate designs, and multidisciplinary design analysis and optimization (MDAO) approach. This research is exploring the use of parametric curves to alter the design shapes within an MDAO framework to improve design, reduce analysis’ computation time and ensure economic feasibility.
This thesis conducted a detailed literature review on shape parameterization techniques and MDAO framework for floating offshore substructures, highlighting research gaps related to their design. The focus of this thesis is to develop a conceptual platform for the design, analysis, and optimization of floating substructures for offshore wind turbine systems using shape parameterization techniques within an MDAO framework. This thesis utilized shape parameterization techniques like the Non-Uniform Rational B-Spline approximation curve characterized with local propagation shape control properties within Sesam GeniE and hydrodynamic analysis tools using the potential flow methodology (HydroD and Wave Analysis by Diffraction and Morisson theory - WADAM). Other shape parameterization techniques like the Cubic Spline, Cubic Hermite Spline and B-Spline approximation curve along with the Non-Uniform Rational B-Spline were assessed. The B-spline parameterization technique is the best performance curve using the Technique for Order of reference by Similarity to Ideal Solution (TOPSIS) to assess the curves given a set of criteria amongst which are computational time, curve continuity and propagation properties and minimizing the objective function. These tools are interfaced on a developed platform with glue codes using Python object-oriented programming language. The automated process within the interface platform includes generating panel model design geometry based on a set of design variables provided, modelling the ballast compartment, meshing the models in preparation for hydrodynamic assessment, evaluating mass distribution and buoyancy with the derivation of the ballast mass distribution and conducting a hydrostatic assessment. The developed platform is further integrated with the gradient-free pattern search optimization algorithm with specified objective functions and constraints to select the most feasible design concept.
The developed model, framework, and approaches in this thesis - especially the concept of shape parameterization within a multidisciplinary design analysis and optimization framework are of potentially high value for both research and the floating offshore wind industrial sector. The achievements of this thesis are summarized herein.
1.
This thesis introduces a simplified and innovative design approach by integrating parametric curves into a Multidisciplinary Design Analysis and Optimization (MDAO) framework. This integrated method allows for the exploration of an extensive design space, facilitating the selection of an optimal design within a significantly reduced computational time frame.
2.
The thesis evaluates the performance of a set of parametric curves—Cubic Spline, Cubic Hermite Spline, B-Spline, and Non-Uniform Rational B-Spline (NURBS)—within the MDAO framework. The evaluation, based on a set of performance criteria employing the multicriteria decision matrix approach of TOPSIS, identifies B-Spline as the top performer, followed by the Cubic Spline, NURBS, and Cubic Hermite Spline.
3.
The thesis demonstrates that optimizing the shape of a Spar platform using the NREL 5MW turbine in a 30MW configuration has the potential to reduce the levelized cost of energy by up to 8% compared to conventional designs. This finding underscores the economic viability and efficiency gains achievable through shape optimization approach.
This thesis provides valuable insights to diverse future applications, including enhanced design efficiency, reduced computational time for design and analysis, generation of unique design concepts for improved hydrodynamic performance, potential capital cost reduction, and lowered Levelized Cost of Energy (LCOE). Additionally, it paves the way for the advancement of advanced manufacturing techniques for unique shapes of floating foundations. These applications underscore the significance of the developed model framework, and approaches in advancing research, refining design practices, and fostering the development of economically viable and reliable support structures for floating offshore wind turbines.The urgent need to reduce greenhouse gases to attain net zero emission and reverse climate change has put the world at a turning point to explore cleaner form of energy generation. This has spiked an increase in the offshore wind forms of energy generation and, most recently, a focus on the Floating Offshore Wind Turbine (FOWT) sector. However, despite the advantages of FOWT installations amongst which are; less environmental impact and accessibility to deeper waters for richer wind resources needed for significant power generation, the technology is presently still economically less viable in comparison to the fixed bottom foundation counterpart. Several research studies, aimed at ensuring the economic feasibility of FOWT have been performed, such as floating foundation upscaling, surrogate designs, and multidisciplinary design analysis and optimization (MDAO) approach. This research is exploring the use of parametric curves to alter the design shapes within an MDAO framework to improve design, reduce analysis’ computation time and ensure economic feasibility.
This thesis conducted a detailed literature review on shape parameterization techniques and MDAO framework for floating offshore substructures, highlighting research gaps related to their design. The focus of this thesis is to develop a conceptual platform for the design, analysis, and optimization of floating substructures for offshore wind turbine systems using shape parameterization techniques within an MDAO framework. This thesis utilized shape parameterization techniques like the Non-Uniform Rational B-Spline approximation curve characterized with local propagation shape control properties within Sesam GeniE and hydrodynamic analysis tools using the potential flow methodology (HydroD and Wave Analysis by Diffraction and Morisson theory - WADAM). Other shape parameterization techniques like the Cubic Spline, Cubic Hermite Spline and B-Spline approximation curve along with the Non-Uniform Rational B-Spline were assessed. The B-spline parameterization technique is the best performance curve using the Technique for Order of reference by Similarity to Ideal Solution (TOPSIS) to assess the curves given a set of criteria amongst which are computational time, curve continuity and propagation properties and minimizing the objective function. These tools are interfaced on a developed platform with glue codes using Python object-oriented programming language. The automated process within the interface platform includes generating panel model design geometry based on a set of design variables provided, modelling the ballast compartment, meshing the models in preparation for hydrodynamic assessment, evaluating mass distribution and buoyancy with the derivation of the ballast mass distribution and conducting a hydrostatic assessment. The developed platform is further integrated with the gradient-free pattern search optimization algorithm with specified objective functions and constraints to select the most feasible design concept.
The developed model, framework, and approaches in this thesis - especially the concept of shape parameterization within a multidisciplinary design analysis and optimization framework are of potentially high value for both research and the floating offshore wind industrial sector. The achievements of this thesis are summarized herein.
1.
This thesis introduces a simplified and innovative design approach by integrating parametric curves into a Multidisciplinary Design Analysis and Optimization (MDAO) framework. This integrated method allows for the exploration of an extensive design space, facilitating the selection of an optimal design within a significantly reduced computational time frame.
2.
The thesis evaluates the performance of a set of parametric curves—Cubic Spline, Cubic Hermite Spline, B-Spline, and Non-Uniform Rational B-Spline (NURBS)—within the MDAO framework. The evaluation, based on a set of performance criteria employing the multicriteria decision matrix approach of TOPSIS, identifies B-Spline as the top performer, followed by the Cubic Spline, NURBS, and Cubic Hermite Spline.
3.
The thesis demonstrates that optimizing the shape of a Spar platform using the NREL 5MW turbine in a 30MW configuration has the potential to reduce the levelized cost of energy by up to 8% compared to conventional designs. This finding underscores the economic viability and efficiency gains achievable through shape optimization approach.
This thesis provides valuable insights to diverse future applications, including enhanced design efficiency, reduced computational time for design and analysis, generation of unique design concepts for improved hydrodynamic performance, potential capital cost reduction, and lowered Levelized Cost of Energy (LCOE). Additionally, it paves the way for the advancement of advanced manufacturing techniques for unique shapes of floating foundations. These applications underscore the significance of the developed model framework, and approaches in advancing research, refining design practices, and fostering the development of economically viable and reliable support structures for floating offshore wind turbines
Multidisciplinary design analysis and optimization of floating offshore wind turbine substructures : a review
No full textThe development of novel energy technologies to meet net zero carbon emission is essential in the provision of solutions to realize an increasing worldwide demand for renewable energy. Floating Offshore Wind Turbine (FOWT) is one of the emerging technologies to exploit the vast wind resources available in deep waters within the offshore wind sector. However, as a result of the complexity of a FOWT system, bringing FOWT technology up to speed requires a detailed understanding of the different disciplines within the system and the relationship between the FOWT system and the dynamics of the marine environment; hence, the need for Multidisciplinary Design Analysis and Optimization (MDAO) of the system. This paper reviews the MDAO of FOWT substructures / platforms proposed in the literature. This review covers an overview of floating offshore wind turbine substructures’ concepts, the design using geometric shape parameterization techniques and the analysis approaches (time and frequency domain) for response assessment of the FOWT system. It also provides a comprehensive review of MDAO frameworks for FOWT substructures. Regarding the optimization aspect, a review of some optimization algorithms used for floating offshore wind turbine substructure is provided, i.e., from the global search heuristic and meta-heuristics algorithms to the local search gradient-based optimization algorithms. This work further identifies the research gaps in MDAO for FOWT substructures. The main proposed future research areas to address these gaps are: increasing design space richness by adopting more advanced parametrization techniques to represent the platform geometry (and other characteristics), utilize surrogate/meta models to replace the most computationally expensive high-fidelity models needed for quick sensitivity studies before detailed analyses on selected models are conducted, and exploring the upscaling of the geometric design parameters of an optimal shape parameterized FOWT platforms derived from existing designs which can be coupled with new generation highly rated and heavier turbines
Parametrisation scheme for multidisciplinary design analysis and optimisation of a floating offshore wind turbine substructure – OC3 5MW case study
No full textAbstract: The development of novel energy technologies is considered imperative in the provision of solutions to meet an increasing global demand for clean energy. Floating Offshore Wind Turbine (FOWT) is one of the emerging technologies to exploit the vast wind resources available in deeper waters. To lower the levelized cost of energy (LCOE) or optimise the performance response associated with a FOWT system, a detailed understanding of the different disciplines (Aero-Hydro-Servo-Elastic) within the system and the relationship between the FOWT system and the dynamics of the marine environment is required. This requires an efficient Multidisciplinary Design, Analysis and Optimisation (MDAO) framework for FOWT systems to reduce the capital cost and increase dynamic performance. A key component of any MDAO framework is the shape parameterisation scheme, as it enables the modelling of a large array of platform designs with different geometric shapes using limited number of parameters. This work focuses on the B-Spline parameterisation modelling technique of OC3 spar-buoy and the use pattern search optimization algorithm to select the optimal design variants. The parametrisation technique is implemented in an analysis framework, where a B-spline library from Sesam GeniE is used to model each design representation, and a potential flow frequency domain analysis solver (HydroD/Wadam) is used for the hydrodynamic analysis. Validation of the selected designs within the design space is conducted with a benchmark NREL5MW spar-buoy hydrodynamic response results in literature with the hydrodynamic response of the frequency domain modelling approach using Sesam GeniE and HydroD/Wadam. This analysis process shows a high accuracy in response results between the OC3 spar-buoy in literature and the OC3 spar-buoy model design using B-Spline parametrization technique. Key performance metrics like the cost of materials and root mean square (RMS) of the nacelle acceleration also show improvement with the design variants compared to estimation from OC3 design in literature
STRATEGIES FOR THE PRESERVATION OF ELECTRONIC RECORDS IN UNIVERSITY LIBRARIES IN NIGERIA
No full textPage 1. 5th of October, 2018 ICERI2018 Local Organising Committee ABSTRACT ACCEPTANCE LETTER This is a confirmation that the abstract entitled: “STRATEGIES FOR THE PRESERVATION OF ELECTRONIC RECORDS IN UNIVERSITY LIBRARIES IN NIGERIA” Author(s): Promise Ilo, Michael Fagbohun, Jerome Idiegbeyan-Ose, Ugwunwa Esse, Nwanne Nwokeoma, Ifeakachuku Osinulu, Olajumoke Olawoyin, Oyeronke Adebayo has been accepted as ORAL presentation at ICERI2018. Name of event: ICERI2018 (11th annual International Conference of Education, Research and Innovation) Dates: 12th-14th of November, 2018 Place: Seville (Spain) Organising entity: IATED IATED Academy. email: [email protected] – Tel.: (+34) 96 344 62 37 – Fax: (+34) 96 206 59 18 iated.or
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