Thesis (M.S.)--Naval Postgraduate School, 1995. / "September, 1995." Includes bibliographical references (p. 107-109).

Thesis (Ph. D.)--University of California, 1925. / Hilgardia, a journal of agricultural science, v. 2, no. 14. April, 1927, with a special thesis t.p. attached to the cover. "Literature cited": p. 527-528.

Thesis (Ph. D.)--University of Chicago, Department of Physics, December 2002. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.) - University of Queensland, 2003. / Includes bibliography.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1982. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 159-165).

Thesis (MScIng)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

Techn. University, Diss., 2004--Berlin.

Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 199-210). Available also in a digital version from Dissertation Abstracts.

First observed as early as redshift z = 7 and now thought to be found at the centre of every massive galaxy in the local Universe, the evolution history of supermassive black holes (SMBHs) spans over 13 billion years. In this thesis, the coevolution between SMBHs and their host galaxies is studied using a set of hydrodynamical simulations to isolate different components of the interaction between black holes and cosmic gas. The simulations range from black hole accretion in an idealised context to the impact of feedback in the cosmological simulations of the HORIZON suite. The origin of SMBHs during the first billion years of the Universe is a highly non-linear problem, where small-scale behaviour influences large- scale behaviour and vice versa. Gas fuelling a black hole flows from the cosmic web, through its host galaxy and into the black hole's gravitational potential, before eventually reaching its event horizon. Even discounting the complex physical processes at play, resolving the 19 orders of magni- tude in spatial scale involved is beyond the capabilities of current simula- tions. Some of the length scales therefore have to be covered by sub-grid algorithms which need to be able to handle a wide range of environments. Idealised accretion simulations presented in this thesis show that the Bondi-Hoyle-Lyttleton (BHL) accretion algorithm is sufficiently versatile. It automatically determines the accretion rate onto the black hole by the mass flux into its accretion region when the black hole's gravitational po- tential becomes resolved. The accretion rate onto the black hole therefore naturally converges to the correct solution once the size of the accretion region approaches the physical size of the black hole. A drag force algo- rithm that compensates for unresolved dynamical friction, on the other hand, produces a force on the black hole that can unphysically accelerate it relative to the bulk flow of the gas. It needs to be switched off when gas properties are measured within the black hole's gravitational potential. A study of black hole accretion within an isolated cooling halo confirms that the accretion algorithm is able to handle the flow configurations en- countered within an evolving galaxy. To ensure gas is always accreted within the black hole's gravitational potential, a refinement algorithm called "zoom-within-zoom" is introduced in this thesis. It allows the black hole environment to be resolved by orders of magnitude above that of its host galaxy. A low mass seed black hole with a strong drag force early on takes advantage of this extra information during the black hole's early evolution. In the longer term, resolving gas clouds in the black hole vicin- ity to sub-pc scales has a lasting impact on both the mass evolution and duty cycle of massive black holes. Sub-pc size clumps also play a deciding role in the first 200 Myr of evo- lution of a SMBH progenitor in a full cosmological context: 90% of its mass is gained through interactions with dense clumps, which fuel super- Eddington accretion bursts. Once the gas within the host galaxy settles into a rotationally supported disc, star formation and black hole accre- tion slow down. As both primarily occur within the central 30 pc of the compact host galaxy, star formation in proto-galaxies has a major impact on black hole accretion even in the absence of feedback. At low redshift, on the other hand, feedback becomes the crucial link between a SMBH and its host galaxy. A comparison of two simulations from the HORIZON suite, run with and without active galactic nuclei (AGN) feedback respectively, shows that AGN feedback is able to prevent as much as 90% of the stellar mass from forming in the most massive galaxies. Quenching proceeds via a combination of AGN driven outflows and reduced inflows and evolves with redshift as the M_SMBH - M_* relation flattens from z = 5 to z = 0. In conclusion, neither the evolution of galaxies nor that of black holes can be understood without the context of the other. At high redshift, the competition between star formation and black hole accretion inside the compact host galaxy intrinsically links the origin of SMBHs to the early evolution of galaxies. At low redshift, AGN feedback modulates the gas supply of the host galaxy, which has a lasting impact on star formation. The coevolution of black holes and galaxies therefore spans their entire history.

The focus of this research is the study of lagoon ecosystem interaction and adjustment of the lagoon floor morphologies, water dynamics and sequences of change involving the motion of sediment. The aim of the study is to implement a functional mechanism to evaluate and analyse changes in the Lagos Lagoon and its ecosystem, with the objectives: (i) to investigate the extent and impact of urban expansion on the Lagoon coastline and its ecosystem; (ii) to quantify changes in the spatial extent of mangroves by use of satellite images from 1984 to 2016; (iii) to investigate the spatial dynamics of the Lagoon water floor and estimate its flushing time, (iv) to investigate the behaviour and relationship pattern of the Lagoon hydrodynamic parameters;, (v) to collect sediment samples from the Lagoon, analyse their settling behaviour and particle size distribution (PSD) in order to study their spatial evolution and characterisation; and (vi) to initiate a model that can predict the influence of sea level rise on the Lagoon ecosystem. The existing problem of an overcrowded human population in Lagos, the incessant repository of industrial effluence into its Lagoon, and increased flooding from the immediate watershed generate the research questions for this thesis. Lack of studies in the areas of morphodynamics and hydrodynamics on the Lagoon is a gap in the body of coastal knowledge, especially the temporal and long term dynamics of a significant Lagoon like that of Lagos. Understanding the dynamics of the Lagoon will enhance efficient monitoring, sustainable management and hence reveal the great importance the Lagoon preserves for the coastal region. Landsat images (1984 – 2016) of the study area (Lagos Lagoon) and its ecosystem were obtained for some specific data derivations. Land Surface Temperature (LST), NDVI and delineated Lagoon coastline were derived from the images. An Environment for Visualizing Images (ENVI) and a Geographic Information System (GIS) were used to extract land classification information, likewise, the GIS was used to develop a model for investigating the Lagoon coastline changes. With the use of ENVI and GIS software, land classification types were derived with the percentage of the coverage area for each land use classification for the years of study. A novel empirical method was designed to collect in-situ hydrodynamic data for both the dry and wet seasons in 2014, this was correlated and analysed using a case study approach. Also, in-situ bathymetric data was collected in 2014 to join the 2008 available data for studying the changes in the Lagoon water bed morphology. Functional models were used to examine the interaction of the various hydrodynamic information that was studied on the Lagoon. Results and inferences from the study show that the wetland of the system is depleting rapidly with increase urbanisation. In both lateral and vertical directions, the morphological shape of the Lagoon is reducing both in size and depth. The result from the model that investigated the system coastline indicates that reclamation and recession are taking place on the Lagoon coast at an approximate ratio of 4 to 1 whereas, the total surface area has reduced to approximately 204.51km2 as opposed to its approximate area of 208km2 as at the year 2010. The results from the analysis of the Lagoon salinity implies a wide salinity variation between the dry and the wet season; this confirms the system as brackish water in the dry season and freshwater in the wet season. Other inferences reveal the critical point of well-mixed water mass, significant vertical mixing during the wet season and a stable state during the dry season. In overview, the ratio of the Lagoon stratification during the dry season to that of the wet season is approximately 1 to 7 and flushing time of approximately 26 days and 22 days respectively. Lastly, the Lagoon possesses a varying settling velocity that is uniquely related to the diameter of its particles at various spatial locations. This research has been able to provide baseline investigations concerning the morphology and hydrodynamic study of the Lagos Lagoon.