DSpace Collection:http://theses.ncl.ac.uk/jspui/handle/10443/882024-02-08T04:02:41Z2024-02-08T04:02:41ZModelling and simulation of organic Rankine cycle waste heat recovery system with the operational profile of a shipNg, Chun Weehttp://theses.ncl.ac.uk/jspui/handle/10443/58702023-11-01T09:11:57Z2022-01-01T00:00:00ZTitle: Modelling and simulation of organic Rankine cycle waste heat recovery system with the operational profile of a ship
Authors: Ng, Chun Wee
Abstract: Organic Rankine cycle (ORC) is a promising new technology to improve the energy
efficiency of ships by recovering energy from the diesel engine’s waste heat. Unlike land-based
applications of ORC in geothermal or biomass power plants, the temperature and flow of the
waste heat source onboard a ship vary with its operational profile and environmental conditions
as it sails around the world. In addition, the design of the ORC also involves multiple design
options starting from the selection of cycle configuration, working fluid, components and
control strategy that are peculiar to ship operations. All these make it difficult to compare
different options objectively and efficiently.
A system modelling and simulation approach that requires minimal data input to assess
the feasibility of ORC onboard ships is proposed using a commercial-off-the-shelf software
tool, Amesim. A novel waste heat source model is developed based on the generic operational
profile for a ship and a fit-for-purpose diesel engine waste heat model. This is followed by a
detailed analysis of the various ORC design options for marine applications that will provide a
foundation on which advanced thermoeconomic optimisation can be performed to find the
optimum solution. The results from the models are verified with other studies and also validated
with experiments where available. The case study on the offshore service vessel demonstrated
how the feasibility of different ORC can be affected by changing the generic operational profile.
The proposed methodology has contributed to the research field by providing a holistic
and systematic way for the shipowners to justify their investment decision on adopting ORC on
their ships based on its thermal, economic and environmental performance taking into account
the ship’s operational profile. Waste heat recovery improves the overall energy efficiency of
their shipboard energy systems and will help in the overall strategy of decarbonising the
maritime industry.
Description: PhD Thesis2022-01-01T00:00:00ZSocio-ecological indicators for sustainable management of global marine biodiversity conservation using sharks as a model speciesRobinson, Daniellehttp://theses.ncl.ac.uk/jspui/handle/10443/57102023-02-10T16:26:02Z2022-01-01T00:00:00ZTitle: Socio-ecological indicators for sustainable management of global marine biodiversity conservation using sharks as a model species
Authors: Robinson, Danielle
Abstract: Global biodiversity is disappearing at an unprecedented rate; sharks are currently among the most threatened vertebrate groups with widespread overexploitation leaving 31% of all species at risk of extinction. Since 2009, 17 coastal nations have adopted a precautionary approach banning all commercial shark fishing. However, evaluating effectiveness of these ‘shark sanctuaries’ is impeded by a lack of robust data. Evidence-based conservation urgently requires data against which socio-ecological change can be measured to assess efficacy of policy and management interventions. This thesis takes an interdisciplinary approach to advance understanding of the complexities of shark conservation within one of the world’s principal shark sanctuaries - the Maldives. Historical abundance trends derived from fisher Local Ecological Knowledge (LEK, 87 interviews) showed substantial declines in shark population abundance (>65%) and distribution (>60%) between 1970-2019. Validation of contemporary spatial LEK using Baited Remote Underwater Videos (BRUVs, 50 hours of footage) highlighted the potential of LEK to provide fine-scale distribution data for shark populations in data poor regions. Analysis of BRUVs (464 hours of footage) and citizen science data (2,024 dives) over a 5-year period (2016-2020) revealed historical population declines have now been halted and suggests species abundances are stable following sanctuary implementation. However, positive correlations between prey and reef shark abundance raises uncertainty over the long-term efficacy of sanctuaries, which still permit exploitation of prey species. Interviews with fishers (n = 103) identified correlations between fisher characteristics, perceptions, and support for the Maldives shark sanctuary. Findings identified several management actions that could increase support: increasing stakeholder participation and representation (voice to capture local knowledge); mitigation of the costs associated with fisher-shark interactions and increasing transparency in management decision making. The potential severity and inequity in livelihood costs associated with shark sanctuaries was also highlighted revealing that small-scale reef fishers were disproportionally impacted compared to pelagic tuna fishers. This thesis highlights the importance of integrating human and ecological dimensions into shark conservation to tailor measures more likely to be effective in specific contexts and suggests that low support for sanctuary regulations, fisher-shark conflict and overexploitation of reef resources, could hinder long-term population recovery. Findings outline rapid, cost-effective approaches towards generating priority data to provide a basis for evidence-based management that will help define future efforts to enhance shark conservation in the context of achieving the UN Sustainable Development Goal (SDG) 14.
Description: Ph. D. Thesis2022-01-01T00:00:00ZMethodology for managing shipbuilding projectby integrated optimalityIslam, MD Tariqulhttp://theses.ncl.ac.uk/jspui/handle/10443/56802023-02-09T15:16:10Z2022-01-01T00:00:00ZTitle: Methodology for managing shipbuilding projectby integrated optimality
Authors: Islam, MD Tariqul
Abstract: Small to medium shipyards in developing shipbuilding countries face a
persistent challenge to contain project cost and deadline due mainly to the
ongoing development in facility and assorted product types. A methodology
has been proposed to optimize project activities at the global level of project
planning based on strength of dependencies between activities and
subsequent production units at the local level. To achieve an optimal
performance for enhanced competitiveness, both the global and local level of
shipbuilding processes must be addressed. This integrated optimization
model first uses Dependency Structure Matrix (DSM) to derive an optimal
sequence of project activities based on Triangularization algorithm. Once
optimality of project activities in the global level is realized then further
optimization is applied to the local levels, which are the corresponding
production processes of already optimized project activities. A robust
optimization tool, Response Surface Method (RSM), is applied to ascertain
optimum setting of various factors and resources at the production activities.
Data from a South Asian shipyard has been applied to validate the fitness of
the proposed method. Project data and computer simulated data are
combined to carry out experiments according to the suggested layout of
Design of Experiments (DOE). With the application of this model, it is possible
to study the bottleneck dynamics of the production process. An optimum
output of the yard, thus, may be achieved by the integrated optimization of
project activities and corresponding production processes with respect to
resource allocation. Therefore, this research may have a useful significance
towards the improvement in shipbuilding project management.
Description: PhD Thesis2022-01-01T00:00:00ZToxicity of engineered nanoparticles to marine bivavle molluscsButt, Sana Akramhttp://theses.ncl.ac.uk/jspui/handle/10443/43302019-05-24T14:39:43Z2018-01-01T00:00:00ZTitle: Toxicity of engineered nanoparticles to marine bivavle molluscs
Authors: Butt, Sana Akram
Abstract: Engineered nanoparticles (ENPs) are increasingly used in manufacturing and consumer products. Their environmental release is a concern given their toxicological effects, which may include interference with cellular electron transport, reactive oxygen species generation, nucleic acid damage, protein oxidation, and cell membrane disruption. This thesis evaluated ENP effects on two tropical filter feeding bivalves (Amiantis umbonella and Asaphis violascens). Nano-silver and nano-titanium dioxide were evaluated over acute (48 hour; concentration 0.05, 0.2, 1, 2 mg/l) and chronic (4-weeks; concentration 0.05 mg/l) exposures. Chronic exposures were also conducted with nano- and bulk-copper and zinc oxides. Bivalve functional activity was measured as particle (microalgae) clearance rate. Simultaneously, a multi-biomarker approach (lipid peroxidation, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase, and metallothionein) was used, supported by histopathology, to determine potential metabolic and cellular effects in gill and digestive gland tissues. Responses varied with nanoparticle type, concentration, exposure period, and species. Acute exposure triggered concentration dependent changes as clearance rate reduced with increasing concentration and exposure duration. Gills and digestive glands revealed oxidative injury; however, the respondent antioxidant defence biomarkers varied. Antioxidant enzyme levels were generally lower in the digestive gland with effects more evident at 0.05 mg/l. Bivalves, particularly A. umbonella, ceased filtering at higher concentrations but still registered oxidative injury. Acute exposure at lower concentrations enhanced antioxidant defence; however, cellular damage occurred. Chronically exposed animals were capable of ameliorating some of the damage. Membrane lipid peroxidation by nano-copper and zinc oxide was higher than their bulk states. Histopathology revealed morphological alterations in gills and digestive glands, particularly over longer exposures. Protein expression was examined (SDS-PAGE) in chronically exposed tissues with some changes common to all nanoparticles whereas others were nanoparticle specific. The present study indicates oxidative injury in marine bivalves exposed to ENPs with the gills and digestive gland as target organs.
Description: PhD Thesis2018-01-01T00:00:00Z