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Inverse modelling and optimisation in numerical groundwater flow models using proportional orthogonal decompositionWise, John Nathaniel 03 1900 (has links)
Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Numerical simulations are widely used for predicting and optimising the
exploitation of aquifers. They are also used to determine certain physical parameters,
for example soil conductivity, by inverse calculations, where the model
parameters are changed until the model results correspond optimally to measurements
taken on site. The Richards’ equation describes the movement of an
unsaturated fluid through porous media, and is characterised as a non-linear
partial differential equation. The equation is subject to a number of parameters
and is typically computationally expensive to solve. To determine the parameters
in the Richards’ equation, inverse modelling studies often need to be undertaken.
In these studies, the parameters of a numerical model are varied until
the numerical response matches a measured response. Inverse modelling studies
typically require 100’s of simulations, which implies that parameter optimisation
in unsaturated case studies is common only in small or 1D problems in the
literature.
As a solution to overcome the computational expense incurred in inverse
modelling, the use of Proper Orthogonal Decomposition (POD) as a Reduced
Order Modelling (ROM) method is proposed in this thesis to speed-up individual
simulations. An explanation of the Finite Element Method (FEM) is given using
the Galerkin method, followed by a detailed explanation of the Galerkin POD
approach. In the development of the Galerkin POD approach, the method of
reducing matrices and vectors is shown, and the treatment of Neumann and
Dirichlet boundary values is explained.
The Galerkin POD method is applied to two case studies. The first case study
is the Kogelberg site in the Table Mountain Group near Cape Town in South Africa.
The response of the site is modelled at one well over the period of 2 years, and is
assumed to be governed by saturated flow, making it a linear problem. The site
is modelled as a 3D transient, homogeneous site, using 15 layers and ≈ 20000
nodes, using the FEM implemented on the open-source software FreeFem++.
The model takes the evapotranspiration of the fynbos vegetation at the site into
consideration, allowing the calculation of annual recharge into the aquifer. The
ROM is created from high-fidelity responses taken over time at different parameter
points, and speed-up times of ≈ 500 are achieved, corresponding to speed-up
times found in the literature for linear problems. The purpose of the saturated
groundwater model is to demonstrate that a POD-based ROM can approximate the
full model response over the entire parameter domain, highlighting the excellent
interpolation qualities and speed-up times of the Galerkin POD approach, when
applied to linear problems.
A second case study is undertaken on a synthetic unsaturated case study,
using the Richards’ equation to describe the water movement. The model is a 2D
transient model consisting of ≈ 5000 nodes, and is also created using FreeFem++.
The Galerkin POD method is applied to the case study in order to replicate the
high-fidelity response. This did not yield in any speed-up times, since the full
matrices of non-linear problems need to be recreated at each time step in the
transient simulation.
Subsequently, a method is proposed in this thesis that adapts the Galerkin POD
method by linearising the non-linear terms in the Richards’ equation, in a method
named the Linearised Galerkin POD (LGP) method. This method is applied to
the same 2D synthetic problem, and results in speed-up times in the range of
10 to 100. The adaptation, notably, does not use any interpolation techniques,
favouring a code intrusive, but physics-based, approach. While the use of an
intrusively linearised POD approach adds to the complexity of the ROM, it avoids
the problem of finding kernel parameters typically present in interpolative POD
approaches.
Furthermore, the interpolation and possible extrapolation properties inherent
to intrusive POD-based ROM’s are explored. The good extrapolation properties,
within predetermined bounds, of intrusive POD’s allows for the development of
an optimisation approach requiring a very small Design of Experiments (DOE)
sets (e.g. with improved Latin Hypercube sampling). The optimisation method
creates locally accurate models within the parameter space using Support Vector
Classification (SVC). The region inside of the parameter space in which the
optimiser is allowed to move is called the confidence region. This confidence
region is chosen as the parameter region in which the ROM meets certain accuracy
conditions. With the proposed optimisation technique, advantage is taken of the
good extrapolation characteristics of the intrusive POD-based ROM’s. A further
advantage of this optimisation approach is that the ROM is built on a set of
high-fidelity responses obtained prior to the inverse modelling study, avoiding
the need for full simulations during the inverse modelling study.
In the methodologies and case studies presented in this thesis, initially infeasible
inverse modelling problems are made possible by the use of the POD-based
ROM’s. The speed up times and extrapolation properties of POD-based ROM’s
are also shown to be favourable.
In this research, the use of POD as a groundwater management tool for saturated and unsaturated sites is evident, and allows for the quick evaluation of
different scenarios that would otherwise not be possible. It is proposed that a form
of POD be implemented in conventional groundwater software to significantly
reduce the time required for inverse modelling studies, thereby allowing for more
effective groundwater management. / AFRIKAANSE OPSOMMING: Die Richards vergelyking beskryf die beweging van ’n vloeistof deur ’n onversadigde
poreuse media, en word gekenmerk as ’n nie-lineêre parsiële differensiaalvergelyking.
Die vergelyking is onderhewig aan ’n aantal parameters en
is tipies berekeningsintensief om op te los. Om die parameters in die Richards
vergelyking te bepaal, moet parameter optimering studies dikwels onderneem
word. In hierdie studies, word die parameters van ’n numeriese model verander
totdat die numeriese resultate die gemete resultate pas. Parameter optimering
studies vereis in die orde van honderde simulasies, wat beteken dat studies wat
gebruik maak van die Richards vergelyking net algemeen is in 1D probleme in
die literatuur.
As ’n oplossing vir die berekingskoste wat vereis word in parameter optimering
studies, is die gebruik van Eie Ortogonale Ontbinding (POD) as ’n Verminderde
Orde Model (ROM) in hierdie tesis voorgestel om individuele simulasies te versnel
in die optimering konteks. Die Galerkin POD benadering is aanvanklik ondersoek
en toegepas op die Richards vergelyking, en daarna is die tegniek getoets op
verskeie gevallestudies.
Die Galerkin POD metode word gedemonstreer op ’n hipotetiese gevallestudie
waarin water beweging deur die Richards-vergelyking beskryf word. As gevolg
van die nie-lineêre aard van die Richards vergelyking, het die Galerkin POD
metode nie gelei tot beduidende vermindering in die berekeningskoste per simulasie
nie. ’n Verdere gevallestudie word gedoen op ’n ware grootskaalse terrein in
die Tafelberg Groep naby Kaapstad, Suid-Afrika, waar die grondwater beweging
as versadig beskou word. Weens die lineêre aard van die vergelyking wat die
beweging van versadigde water beskryf, is merkwaardige versnellings van > 500
in die ROM waargeneem in hierdie gevallestudie.
Daarna was die die Galerkin POD metode aangepas deur die nie-lineêre terme
in die Richards vergelyking te lineariseer. Die tegniek word die geLineariserde
Galerkin POD (LGP) tegniek genoem. Die aanpassing het goeie resultate getoon,
met versnellings groter as 50 keer wanneer die ROM met die oorspronklike simulasie
vergelyk word. Al maak die tegniek gebruik van verder lineariseering, is
die metode nogsteeds ’n fisika-gebaseerde benadering, en maak nie gebruik van
interpolasie tegnieke nie. Die gebruik van ’n fisika-gebaseerde POD benaderings
dra by tot die kompleksiteit van ’n volledige numeriese model, maar die
kompleksiteit is geregverdig deur die merkwaardige versnellings in parameter
optimerings studies.
Verder word die interpolasie eienskappe, en moontlike ekstrapolasie eienskappe,
inherent aan fisika-gebaseerde POD ROM tegnieke ondersoek in die
navorsing. In die navorsing word ’n tegniek voorgestel waarin hierdie inherente
eienskappe gebruik word om plaaslik akkurate modelle binne die parameter
ruimte te skep. Die voorgestelde tegniek maak gebruik van ondersteunende vektor
klassifikasie. Die grense van die plaaslik akkurate model word ’n vertrouens
gebeid genoem. Hierdie vertrouens gebied is gekies as die parameter ruimte
waarin die ROM voldoen aan vooraf uitgekiesde akkuraatheidsvereistes. Die
optimeeringsbenadering vermy ook die uitvoer van volledige simulasies tydens
die parameter optimering, deur gebruik te maak van ’n ROM wat gebaseer is op
die resultate van ’n stel volledige simulasies, voordat die parameter optimering
studie gedoen word. Die volledige simulasies word tipies uitgevoer op parameter
punte wat gekies word deur ’n proses wat genoem word die ontwerp van
eksperimente.
Verdere hipotetiese grondwater gevallestudies is onderneem om die LGP en
die plaaslik akkurate tegnieke te toets. In hierdie gevallestudies is die grondwater
beweging weereens beskryf deur die Richards vergelyking. In die gevalle studie
word komplekse en tyd-rowende modellerings probleme vervang deur ’n POD
gebaseerde ROM, waarin individuele simulasies merkwaardig vinniger is. Die
spoed en interpolasie/ekstrapolasie eienskappe blyk baie gunstig te wees.
In hierdie navorsing is die gebruik van verminderde orde modelle as ’n grondwaterbestuursinstrument
duidelik getoon, waarin voorsiening geskep word vir
die vinnige evaluering van verskillende modellering situasies, wat andersins
nie moontlik is nie. Daar word voorgestel dat ’n vorm van POD in konvensionele
grondwater sagteware geïmplementeer word om aansienlike versnellings
in parameter studies moontlik te maak, wat na meer effektiewe bestuur van
grondwater sal lei.
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The commercial and recreational marine skiboat linefisheries in Richards Bay, KwaZulu-Natal.January 2005 (has links)
In order to assess and improve their management, a survey of the commercial and recreational marine linefisheries in Richards Bay was conducted from June 2002 to July 2004. The ultimate aim of this survey was to develop a sound management framework for the commercial and recreational marine Iinefisheries in Richards Bay. Skippers on both commercial and recreational skiboats were all white males in their mid-40s whom were fairly experienced. There were twice as many crew on commercial than recreational skiboats. The crew on commercial skiboats were mostly black males while on recreational skiboats, crew were mostly white males. Slinger was the most important species caught by commercial fishermen off Richards Bay, accounting for the vast majority of catches by number and mass. The total contribution by sparids to commercial catches amounts to approximately 93 % by number and 81 % by mass. Recreational catches comprised a greater variety of species (73 recreational species versus 54 commercial species), signifying a less focussed targeting approach compared to commercial skiboat fishermen. Although slinger also numerically dominated recreational linefish catches, catface rockcod were most important by mass. Although there were five times more recreational outings during the study, total catch by commercial skiboat fishermen was five times higher than that of recreational fishermen. This was expected, as the average duration of each commercial outing is more than twice that of recreational outings and the crew numbers are higher. Commercial skiboat fishermen in Richards Bay are also more effective, as the average number of fish caught per man per hour on commercial skiboats was approximately 4 times greater than that on recreational skiboats. Total estimated catch for the commercial sector was 28 tonnes and 173 tonnes for the recreational sector. Comparison of data between this survey and commercial data available on NMLS showed similar species composition, although the dominance of slinger was 20 % higher in this survey compared to data. Similarly, within the recreational sector, there was a close similarity in catch composition between this survey and that catch inspections. The profit (excluding the costs of fixed assets) that each commercial fisherman earns per month was estimated to be in the region ofR8 500. However, if one examines the value of the commercial linefishery as a whole, it appears that there is a net loss of R90 000 per year, excluding the costs of fixed assets. The discrepancy stems from the disparity between the recorded number of launches and the number reported by skippers. Most of the commercially caught fish are not sold in Richards Bay, but are exported to Gauteng. The average monthly Iinefish catch by commercial fishermen was less than half the average estimated consumption of Iinefish in Richards Bay, and the difference appears to be made up from recreational catches, with many consumers indicating that they either caught their own fish or were given it. Knowledge of and compliance with fishing regulations by commercial and recreational skiboat fishermen in Richards Bay was reasonably good. The main recommendations emanating from this study include continuous monitoring of the Richards Bay commercial and recreational line fishery in order to determine the efficacy of the new regulations, the development of area-based commercial linefishing permits and the possible introduction of restrictions on the sale of fish outside of the Richards Bay area. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.
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Christian education and leadership development in India implications from the theological writing of Lawrence O. Richards /Reddy, Indira J. Richards, Larry, January 1992 (has links)
Thesis (M.A.)--Trinity Evangelical Divinity School, 1992. / Abstract. Includes bibliographical references (leaves 83-96).
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The critical theories of T.S. Eliot and I.A. Richards a study of two efforts to resolve the dichotomy between thought and feeling in modern poetry /Graham, James Clark, January 1940 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1940. / Typescript. Includes abstract and vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 237-240).
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Christian education and leadership development in India implications from the theological writing of Lawrence O. Richards /Reddy, Indira J. Richards, Larry, January 1992 (has links) (PDF)
Thesis (M.A.)--Trinity Evangelical Divinity School, 1992. / Abstract. Includes bibliographical references (leaves 83-96).
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Christian education and leadership development in India implications from the theological writing of Lawrence O. Richards /Reddy, Indira J. Richards, Larry, January 1992 (has links)
Thesis (M.A.)--Trinity Evangelical Divinity School, 1992. / Abstract. Includes bibliographical references (leaves 83-96).
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Studies on dune rehabilitation techniques for mined areas at Richards Bay, NatalMoll, John Bingham January 1993 (has links)
Rehabilitation is a dynamic process influenced by factors related to more than one field of ecology. It is therefore necessary to consider all these components when assessing the rehabilitation, although in the initial stages the successful revegetation of the disturbed areas is the most important criterion. Richards Bay Minerals, on whose mining site this project was carried out, is dredge mining heavy minerals on the north coast of Natal, where they have rehabilitated mined areas since 1978. This project has been carried out to establish: 1) The success of their dune forest rehabilitation using quantitative techniques. 2) The available seed bank in their rehabilitation stands. 3) The similarities in the succession taking place in rehabilitation stands compared to the revegetated stands in the vicinity of Richards Bay. 4) The best methods for creating alternative vegetation communities, especially grasslands, with a high species diversity on the mined tailings. This study reviews only the success of rehabilitation of the natural vegetation but other studies focusing on the insect, reptile, mammal and bird populations are also being undertaken by other researchers. No particular method of determining the success of vegetation rehabilitation has been chosen by restoration ecologists. Therefore in this study a broad range of quantitative techniques were used to show whether successional changes are occurring in the vegetation and physical environment. The results obtained from sampling the rehabilitated vegetation have shown that both the species richness and diversity are increasing as the returned vegetation matures. Levels of soil properties such as Sodium, Phosphate, Calcium and percentage organic matter have also risen with increasing stand age. Community complexity is also increasing with stand age, and TWINSPAN and DECORANA plots have separated out the differently aged stands based on their differences. A "pilot" study was done on the seed bank present in the rehabilitation stands. This has shown the presence of large amounts of early successional, mostly herbaceous species. Seeds of later successional and woody species were scarce which may be a result of the sampling intensity used. However seeds of late successional ground cover species were found in the older stands. Comparisons between the natural revegetation of disturbed areas in the vicinity of Richards Bay and the rehabilitation stands revealed similarities in both species composition and complexity. Species richness and diversity values are comparatively similar for the younger revegetated and older rehabilitation stands, and lWlNSPAN and DECORANA analysis techniques clustered the samples recorded from these areas in close proximity on their relative plots. The oldest revegetated sites contain a number of species found in the rehabilitated vegetation but as Acacia karroo has thinned-out in these stands many of these other species are now mature individuals. Attempts at rehabilitating an area of grassland at Richards Bay Minerals has not produced satisfactory species diversity and experimental manipulations were used to try and increase the diversity of the existing Eragrostis curvula dominated community. Of the several treatments used for the manipulation, a combination of burning and further topsoiling was the most successful in reducing Eragrostis importance and in increasing the species richness. Grassland topsoil spread directly onto the bare tailings produced an extensive vegetation covering over a short period but species richness was not significantly greater than for the existing Eragrostis dominated grassland, and further treatments and management needs to continue if this technique is to be employed. Only a limited amount of alien infestation of the rehabilitated areas was evident from the sampling undertaken during this research. As the removal of alien plants is an ongoing process and the rehabilitation stands are continuously monitored to identify any new invaders, this is not expected to become a problem. From the results of work done overseas and the rehabilitation carried out in South Africa it appears that it is possible to return natural vegetation communities on mined areas. That this is a lengthy process is to be expected but by manipulating the vegetation and continuously monitoring the process it may be possible to speed up development. Areas in need of further research have been identified based on the findings of this project. This will help to reinforce the undertaking of management proposals that will enhance the vegetation recovery and the success of the rehabilitation programme.
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The status of tourism skills development practices for the previously disadvantaged communities around Richards Bay & townshipsCembi, Phumza Happiness January 2011 (has links)
A dissertation submitted to the Faculty of Arts in
partial fulfilment of the requirements for Master's degree in
Recreation and Tourism, in the Department of Recreation and
Tourism at the University of Zululand, South Africa, 2011. / The South African tourism industry has largely been designated as the playing
grounds for the previously advantaged communities [PACs] where they acquire
many benefits, and not in favour of the previously disadvantaged communities
[PDCs]. Various tourism-related government policies and strategies have been
put in place so as to improve the status and access of the previously
disadvantaged communities into the tourism industry. On the one hand, the
tourism policies and strategies are viewed as reverse discrimination by some
previously advantaged individuals [PAIs], while on the other hand, they are
viewed as an outstanding opportunity and justice for many previously
disadvantaged individuals [PDIs]. This is more specifically when the policy of
skills development, among others, is designed to improve the living status and
employment opportunities of the previously disadvantaged communities
[PDCs].
This research study has the intention of investigation the status of tourism skills
development practices for the previously disadvantaged communities around
Richards Bay á Townships. The study also sought to establish whether there
are any emerging opportunities of improving the lot of the black people within
the areas where they stay. In other words, this study views the tourism policies
and strategies as critical for establishing a demographic representation in the
tourism industry. Furthermore, the study believes that in order for these policies
and strategies to succeed they must adopt principles of skills development
practice that are acceptable and well-regarded among the previously
disadvantaged communities in the industry.
The main objectives of this study seek to reveal the status of tourism skills
development practices for the previously disadvantaged communities, in the
study area. This goal may be achieved through objective such as: how
stakeholders understand the importance of tourism skills development practices;
respondents' access to the tourism skills development opportunities; how the
Richards Bay tourism authorities facilitate tourism skills development;
respondents' perceptions of the implementation of the tourism skills
development policies and practices; and establishing whether there are any
tourism skills development practice-benefits for the PDCs in the study area.
The methodology of this study deals with the selection of the sample, instrument
for data collection in 3 Richard Bay Townships and the analysis and
interpretation of data. The form of research approach that was used in this
research was the survey method. The face-to-face interviews were used where
questionnaires were used to collect data from a sample of stakeholders in
Townships. The sample size selected was 132 respondents which are not
necessarily representatives of the entire population of Richards Bay and
Townships. The sample size was categorised into the following stakeholders:
tourism officials [15], service providers [20], and local community [97]. The
sampling technique selected was the stratified random sampling techniques.
In conclusion the study established that, on the whole, the respondents fully
understood the meaning and importance of tourism skills development practices.
The respondents also felt that the skills development opportunities were
inaccessibility in the study area. The findings also indicated that the
respondents felt that the provision of tourism skills development practices and
policies in the area were not adequate. The respondents were seen to perceive
the implementation of the tourism skills development policies and practices as
not up to the required standard. Finally, the respondents felt that the tourism
skills development practice-benefits were not adequate in the study area.
The research study concludes by offering recommendations, which proposed
that all the authorities ranging from tourism, labour, education and municipality
must investment significantly in skills training and development practices.
Finally, the community must be encouraged to learn more about the benefits of
tourism.
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Land use analysis using GIS : a case study of Richards Bay Minerals' Zulti South mining lease area.Oellermann, Carl Gunter. January 2001 (has links)
The past centuries have been marked with massive land conversions from one land use category, usually natural vegetation, to another. The forces that drive these land use changes are complex and poorly understood. However, the study of land has been revolutionised by the introduction of spatial tools such as remote sensing and GIS that automate these complex issues and assist in the solutions of these geographic problems. Land use identification and classification techniques were used in conjunction with GIS to consistently and accurately extract and incorporate land use data from a series of remotely sensed images of Richards Bay Mineral's Zulti South Mineral lease. Eight land use types from Zulti South were identified and mapped from six different remotely sensed images taken at different time periods between the 21 st of September 1990 and the 1st of June 2001. This mapping technique was shown to have an accuracy of 87.6%. The data collated from this study enabled the monitoring and representation of the temporal and spatial differences in land use within a GIS. From the analysis carried in the GIS the land use dynamics within the lease could be quantified and modelled. The time series of the land use datasets indicated how much of the landscape is changing, what changes have occurred and where these changes are taking place. Accurate and timely mapping of land use provides vital information on the state of the mineral lease area and its environment, and facilitates the development of spatial trends from which predictions of land use and land use change can be made. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.
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Assessment of the waste management practices at Transnet National Ports Authority, Port of Richards BayNaidoo, Neal Craig 05 1900 (has links)
Based on literature review, statistics of waste management at ports in South Africa is hard to come by. The research critically assessed the current waste management practices at Transnet National Ports Authority. Transnet National Ports Authority, Port of Richards Bay (TNPA RCB) was used as a case study to examine the different types and quantities of waste produced, analysing the current waste management model as well as determining TNPA RCB compliance to pertinent waste legislation.
A 10 day waste audit was conducted to obtain quantitative data and to identify the different types of waste generated. The baseline data resulting from the waste audit conducted for the first time since the establishment of the TNPA RCB, found 402 kg of general waste generated, 74 kg of this total is segregated for recycling and the remaining 328 kg is landfilled. The overall conclusion gained during compliance audit was that the TNPA RCB was partly compliant with pertinent waste legislation and obligations.
Furthermore, questionnaires about waste were sent to staff members working in offices to get an overview of how they deal with current waste management. A number of barriers to sustainable waste management were identified, including: lack of knowledge and awareness; constraints on facilities and human resources; culture that resists change and contamination. To overcome these, there needs to be education, as well as co-operation between top management, staff and waste service providers to help implement new strategies. The primary conclusions from this dissertation are that there are opportunities to divert waste streams from landfill and to attain a sustainable waste management system at TNPA RCB. / Environmental Sciences / M. Sc. (Environmental Management)
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