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Thesis--Economics--Florence--European university institute, 1994. / Notes bibliogr. en bas de page. Bibliogr. p. 608-633.

This thesis explores the relationship between community gardens in Portland, Oregon, and the refugee integration process. Using interviews and observations of a community garden in southeast Portland, the research explores the actors and organizations working with refugees in community gardens all over the city. The most prominent actors in the community garden networks are referred to as Community Cultivators. These individuals are refugees and also strongly tied to organizations and institutions in Portland. It is through these social networks that Community Cultivators are able to build bridges between their refugee communities and Portland-based organizations, fostering integration. This research also explores how integration happens in the community gardens in Portland and why community gardens are able to foster these relationships. The foundational framework used in this research is Alison Ager and Alistar Strang’s (2008) Indicators of Integration, which is adapted for the unique process of refugee integration through community gardens engagement.

AC or DC has been in the centre of debate since the early days of the electrical system. DC is already proven to be more economical than AC in transmission at elevated power and voltages. Thus, expanding the use of DC to the distribution grids seems promising as most of the distributed generation such as PV generates initial DC voltages and many of the modern loads are using internal DC buses. Still, in order to extend the use of DC to the distribution level a suitable DC distribution grid architecture and a suitable DC/DC converter to serve it should be explored, which is the focus of this Ph.D. A study based on the Libyan grid and loads was carried out to investigate the most suitable DC distribution grid layout. The results showed that DC grid arrangement utilising two port converters have lower total converter losses and smaller converter installed power when compared with arrangements using three ports converter. A multi-cell multi–snubbered three phase dual active bridge (DAB) converter was proposed to serve the chosen DC distribution grid layout. The modular multi-cell multi–snubbered 3 phase DAB converter offered low losses over a wide range of loading profiles. Furthermore, the converter performance can be easily modified to be able to serve a specific DC/DC grid loading profile by altering the snubbers attached to the cells and the power management’s algorithm between the cells while keeping the core cells the same. Extra cells can be added if higher power rating is required, reducing the total cost of expanding the proposed DC distribution system. This thesis is an ambition step on deciding the structure of the futuristic DC grid and the required DC/DC converters to link it is different voltage levels.

Collective or communal housing (Cohousing) is housing featuring joint facilities available to all residents, while the residents also maintain autonomous, self sufficient housing units. The communal spaces form a central characteristic of the housing complex and is not just an added amenity. The shared facilities should encourage and accommodate social interaction, group activities and the coordination and cooperation between residents to carry out common tasks. A distinct infill level in buildings is gradually emerging. This level contains all the equipment, non load-bearing partitions and a substantial amount of services. The infill level restores the building as provider of space and shelter and facilitates the specific needs and preferences of the inhabitants more directly. Traditional notions of the family is being challenged, placing increasing demand on homes to be flexible and responsive to changes in family structure. Since the long-range benefits of a stable community is jeopardised if residents have to move when their spatial requirements change, transformable interiors were used to reduce this risk. Flexibility is largely used in the housing units, relying on advanced computed aided manufacture that is able to fabricate components for easy assembly on site. For the purposes of this thesis an under utilised office building in the Pretoria central business district was chosen to illustrate a cohousing complex in an urban environment. Design energy was focused on designing the communal facilities and a sample housing unit, illustrating the support system and investigating the unit's versatility. / Dissertation (BInt)--University of Pretoria, 2004. / Architecture / unrestricted

In recent years, renewable and distributed generation (DG) systems have contributed towards an efficient and an economic way of transporting electricity to end-users as the generation sources are in general located nearer the loads. DG and renewable energy systems are modifying the old concept of distribution network by instigating a bi-directional power flow into the grid, facilitated through the use of power electronic grid-connected converters. A challenge associated with grid-connected converters arises when they are interacted with a grid that is not stiff, like weak micro grids. Small grid parameter variations in these systems can considerably affect the performance of the converter control and lead to higher values in current total harmonic distortion (THD) and loss of control and synchronization. Thus, the control of grid-connected power converters needs to be regularly updated with latest variation in grid parameters. Model Predictive Direct Power Control (MP-DPC) has been chosen as the control strategy for the work presented in this thesis due to its advantages over traditional control techniques such as multivariable control, no need of phase-locked loops (PLLs) for grid synchronization and avoidance of cascaded control loops. Two novel methods for estimating the grid impedance variation, and hence the grid voltage, are presented in this thesis along with a detailed literature review on control of grid-connected converters with special emphasis on impedance estimation techniques. The first proposed estimation method is based on the difference in grid voltage magnitudes at two consecutive sampling instants while the second method is based on a model-fitting algorithm similar to the concept of cost-function optimization in model predictive control. The proposed estimation methods in this thesis are integrated within the MP-DPC, therefore updating the MP-DPC in real-time with the latest variation in grid impedance. The proposed algorithms provide benefits such as: quick response to transient variations, operation under low values of short-circuit-ratio (SCR), robust MP-DPC control, good reference tracking to grid parameter variations and operation under unbalanced grid voltages. The thesis also presents the advantages and drawbacks of the proposed methods and areas where further improvement can be researched. The work presented has been tested on a three phase two-level grid-connected converter prototype, which is connected to a low voltage substation highly dominated by inductive component of grid impedance. It can be adapted and modified to be used for general grid impedance estimation, medium or high voltage applications, in case of multilevel grid-connected converter topologies or photo-voltaic (PV) grid-connected applications.

In recent years the growth of renewable energy has encouraged the development of HVDC grids. One challenge of building HVDC grids is the power converter response to DC side faults. The full-bridge Modular Multilevel Converter (MMC) is a desired power converter topology which is used in HVDC grids due to its scalability, modularity and capability of blocking DC side faults. Post fault operation of the full-bridge MMC requires the control of power flow, the energy of each sub-module capacitor and the elimination of circulating harmonic current to reduce power loss while DC line-to-ground or DC line-to-line faults exist. This thesis presents a post fault operation method for a full-bridge MMC in order to transmit partial power after a DC line-to-ground fault and provides reactive power after DC line-to-line fault. Simulated results are provide from a point-to-point HVDC system which consists of two eleven-level full-bridge MMC.

In indigenous African societies, cultural expectations compel women to restrict themselves from excelling in whatever they do as a way of conforming to prevailing customary expectations. This is because those women who are said to disregard cultural expectations by aspring to achieve more than their male conterparts face societal consequences. / Thesis (PhD)--University of Pretoria, 2020. / Andrew Mellon Foundation. / African Languages / PhD / Unrestricted

Zimbabwe is endowed with vast mineral resources which can make a significant contribution to the GDP of the country. Amongst the mineral resources found in the country are diamonds, gold and platinum and theses resources need to be properly managed for them to benefit the country through revenue and also creation of opportunities in the country. This means that the existence of vast mineral resources has numerous direct and indirect benefits which have to be utilised fully. The management of the extractives industry in the country requires proper administration and such administration is mandated to the President, in whom all minerals in the country are vested, the Minister of mines and mineral development, the Mining affairs Board and Mining Commissioner(s). The nature of mineral resources requires that all the parties involved in the administration thereof play their roles. Mineral resources are finite and cannot be left to be underground for extended periods as this can lead to sterility. Such a position has led to the government to consider implement the “use it or lose it” policy which in simple terms means that a holder of a mineral claim should exploit it or risk losing it. This study therefore sought to consider the implications of enforcing the policy in the country. This was done by firstly discussing how someone can obtain a limited real right to a mining location to exploit the minerals and this was achieved by looking at the pertinent provisions in the Mines and minerals Act dealing with the grant of licences. The writer thereafter discussed the provisions containing the “use it or lose it” policy to ascertain what the Act stipulates and how it can be enforced. Licences amount to a limited real right and expropriation, the effect of enforcing the policy leads to a violation of property rights which are sought to be protected by the Constitution of the country. A discussion of these provisions and the effect thereof proved that a holder of a right under the Act to exploit minerals would have his right prematurely terminated if he was not working the mining location or was not developing his location. An investigation would need to be done to ascertain the circumstances and the Board will make a recommendation to the President who makes a final decision on expropriation. Compensation following expropriation is not always guaranteed but the Act does not explain how this decision is made and an aggrieved party has recourse to the court system. The writer raised concerns on the violation of property rights in the process when the government is exercising its powers for the benefit of the public. The implementation of the policy is valid but issues of security of tenure are obviously raised and this does not paint a good picture on the government. One must always remember the violent land grab once implemented by the same government. Transparency together with equal and fair treatment was therefore recommended by the writer and a need to have shared responsibility in the decision making to avoid politicised decisions. The writer further recommended that the court system should not be influenced by the powers that be when a decision is being made pertaining the expropriation; the rule of law should therefore be protected. / Mini Dissertation (LLM)--University of Pretoria, 2019. / Public Law / LLM / Unrestricted

The National Cancer Institution reported over 80,000 diagnoses of bladder cancer (BCa) in the United States in 2018. Despite these numbers, minimal research toward developing new diagnostic techniques and treatment options are underway. Evidence suggests a significant increase in non-specific a-naphthyl acetateesterase levels in BCa patient’s urine. There has been little research focused on identification of the esterase present. It is also suggested that elevated oxidative stress resulting in production of reactive oxygen species (ROS) is common in tumorigenic bladder cells as a result of increased metabolic activity. Oxidized protein hydrolase (OPH) is an 80kD serine protease, previously found to be elevated in many other types of cancer. OPH degrades proteins damaged by ROS and also exhibits a highly specific esterase activity toward (AcApNA) N-acetyl-alanyl-p-nitroanilide and ANAA (α-naphthyl N-acetylalaninate) containing substrate. Investigation of OPH expression in BCa could result in development of new diagnostic techniques and possible application toward prodrugs targeting cells with elevated ROS and/or OPH. Due to lack of commercial OPH, a positive control for this protein is needed for testing. To do this E. coli(BL-21 DE-3) were cultured and inserted with pET-21a (+) plasmids containing a human OPH gene insert prior to a His7 tag. After being selectively grown on ampicillin media, the bacteria were induced by IPTG and digested using lysozyme. The soluble rOPH suspended in the supernatant was separated from the pellet by centrifugation and further purified using Ni-NTA resin chromatography columns specific for the His7 tag sequence. The UM-UC-3 bladder cancer cell line, commonly used in published research to screen efficiency of chemotherapeutics, were cultured in accordance to ATCC. These cells were then compared against none tumorigenic bladder cancer cells and rOPH in a series of tests. Sodium dodecylsulfate (SDS) polyacrylamide gel electrophoresis (SDS-PAGE) were transferred for western blot analysis using antibodies specific for human OPH to investigate the expression levels present in cells. Native-PAGE electrophoresis showed OPH esterase activity across these cells using S-ANAA substrate as a specific esterase colorimetric stain. With these results, possible treatment options can be investigated with use of novel prodrug chemotherapy specifically targeting OPH in BCa cells, ultimately leading to apoptosis in effected cells. These events may also lead to possible biomarkers used for easier and earlier diagnosis of BCa across various spectrums.