Doctor of Philosophy (Ph.D.)

Permanent URI for this collectionhttp://192.248.9.226/handle/123/8871

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item: Thesis-Abstract
An Approach to conceptualizing the environmental image of an urban locality for planning
Munasinghe, JN
Recent trends in local level planning have emphasized the importance of enhancing place images. Hence, conceptualizing the form of a locality's image has become a need in urban planning. Having noted the limitations in available approaches, and the knowledge gaps for such conceptualizing through a literature review, this study was undertaken to evolve a conceptual model of the structure of a locality's image. For this purpose the results of an empirical investigation of the inhabitants' cognition were interpreted in the light of theoretical positions established by previous studies. The research was designed on the premises that the 'spatial extent' of the environment constitutes the substantial domain of urban planning and the planners aspire to work in its 'public realm'. Hence, the focus was on the shared spatial references in inhabitants' cognition. The empirical work included a questionnaire survey, a field reconnaissance and a cartographic survey. Referring to the 'invariant' and the 'context specific' characteristics of the findings, it was suggested that the environmental image of a place was a 'unitary' concept and its structure was configured of the 'reference points' both 'collectively' and 'individually' held by the inhabitants. Therefore, the model evolved here was named the unitary image of the place. Its 'collective' domain was shown as the potential area for the urban planners to intervene to work about a locality's image and thereby, to integrate inhabitants' cognition with the planning process. Keywords: Environmental Image, Cognition, Place, Locality, Inhabitants, Spatial Elements.
item: Thesis-Abstract
High-density high-rise vertical living : an approprate housing solution for low-income people in Colombo, Sri Lanka?
Samarathunga, TC; O’Hear, D
A house is a basic and fundamental human need. In a literal sense, a house provides warmth, shelter and security. Beyond its physical nature, the concept of ‘house5 is deeply ingrained in human civilisation as the space where the institution of family is nurtured. It is a place that reflects a person’s identity, living condition, human values, aspirations, future expectations and one’s social and cultural identity. However, despite the global recognition of its importance, many millions of people in the world live either without safe habitable housing or without any housing at all. This situation is common in developing counties, especially in urban areas. The thesis is motivated by a sincere effort to practically address the problems of housing in the city of Colombo, in particular the scarcity ofsustainable habitable housing for low-income people. The Colombo City Development Plan (UDA 2008) revealed that there were 66,000 households within the city of Colombo living in under-served settlements considered unfit for human habitation. This figure represents 51 per cent of the city’s population (UDA 2008). Since gaining independence in 1948, the Sri Lankan Government has devoted much attention to finding a solution to this situation and has introduced a number of policies, programs and projects to address the issue of under-served settlements with varying degrees ofsuccess. High-rise housing for low-income people is one option that has been chosen by the current Sri Lankan government in the hope of re-housing those who currently live in under-served settlements in Colombo in sustainable, safe and affordable housing. At the time of writing this thesis (2012), the construction of nearly 12,000 high rise housing units has commenced with the aim of constructing 35,000 high rise dwellings within the next three years (UDA 2011). However, the appropriateness of high-rise housing for low-income people is a very controversial topic. Some countries have rejected high-rises as an option for low-income housing due to significant failures in the past while other countries have been very successful IV using high-rise housing for low-income people as a way to upgrade the living conditions of the people who live in slums and shanties. Very little research has been done in this sector, especially in Sri Lanka, and this thesis attempts to fill the knowledge gap about the lowincome housing sector in Colombo, discussing the research contribution of the theory, the contribution to the Sri Lankan research and the contribution to the profession. A qualitative research approach was chosen as the most appropriate method for investigating the research problem in depth. This research uses both secondary and primary data collection methods to enhance the quality of the research. Literature review, documentary research, Internet references, case study analysis, observation and key informant interviews are the main data collection strategies which have been used throughout the research. Twelve key informant interviews were conducted with officials in various government ministries, private-sector investors and professionals who are engaged in the housing sector in Colombo city. All participants are senior critical decision-makers and well-known government and private sector experts in the housing field in Sri Lanka. The data and information collected from the key informant interviews, case studies and other sources were scrutinised, edited, coded and analysed using qualitative data-analysing methods. The quality standards of this study take into account construct validity, internal validity, external validity and the study’s reliability. Finally, this research makes recommendations to the professionals and policy-makers who work with high-rise low-income housing on how to minimise the risk associated with highrise low-income housing in Colombo and open a way ofthinking about high-rise low-income housing.
item: Thesis-Abstract
An Investigation of some factors influencing the use of colliery discards as a fill material for reinforced earth construction
(2014-06-06) Fernando, DA
This thesis is concerned with an investigation of some factors influencing the use of coarse colliery discards as a fill material for reinforced earth construction. The work carried out in this study is primarily a laboratory study, investigating the properties of the fill materials, reinforcements and the soil-reinforcement interaction coefficients. Test were carried out on Cardown colliery discards to establish the geotecnical properties and to establish weather the discards satisfied the criteria set out by BE3/78(revised) and the DTp specification for Highway works(1986). Instruments ranging fro free field strain coils were used to measure strains in the soils. All methods utilised are reported. But, the success of the methods considered varied due to the nature of the fill materials.A through investigation was carried out to establish the shear strength envelope. The shear strength envelopes were established, they are as follows: i0 Particle sizes pertaining to the whole grading curve; ii)Specific particles size ranges; These tests indicate that the envelope can e segregated into two sections, one for the low stress region and another for the high stress region. The results of the former indicate tht the shear strength is stress dependent and can be accurately fitted by curvilinear regression analyses. The interaction tests carried out in this study and the data reviewed fro the other sources when represented non-dimentionally indicates that the RMS strips and the Tenser SR2 grinds yield the highest alpha values and hence the coefficients of friction. The result of shales tested with RMS strips yeild the highest coefficients of interaction. Envelopes have been formulated, subsequent to the collection of data for all the materials considered in this study. The results indicates that the alpha values as presented in BE3/78(re viced) are conservative, in the case of the RMS strips. The pull-out tests carried out in this study indicates that the RMS strips are the most efficient of all the conventional strips. The grid tests yielded the highest pull-out forces and they were most efficient of all the reinforcements tested. The field pull-out test data as reported by we indicated that the friction coefficients were lower with respect to the laboratory Data. This can be attributed to the difference in compaction. Comparison of the coefficient of friction indicates that the skin friction tests as measured in the shearbox are lower with respect to the pull-out test data. An equation was formulated using the results of the established Mohr envelopes with respect to particle size, skin friction tests and the spacing of the ribs in a RMS strip. The predicted values are accurate to within 10% of the measured values. The assessments of the cost benefits of using collier discards as the fill materials indicate that the benefit of colliery discard utilization is dependent on the cost of the fill and the haulage costs. With the benefits being over 30% with respect to conventional structures. The results of this study indicate that colliery discards when carefully selected and tested can be used as a fill material in reinforced earth constructions.
item: Thesis-Abstract
Optical properties of likely constituents of interstellar dust
(2014-07-01) Dayawansa, IJ
Optical properties of polyoxymethelene (POM) at room temperature have been measured from the near ultra-violet to infra-red as an initial stage of a line between interstellar dust and organic matter, and we report our results which are particularly relevant to interstellar extinction. There is a strong possibility of a more complex organic component which could significantly contribute to the interstellar extinction. Measurements have also been made of the effect of fast neutron bombardment on the optical properties of quartz (SiO). At a high total flux of neutrons the crystalline quartz will change to its amorphous form which has extinction properties that resemble the interstellar extinction. Extinction due to small particles of several forms of SiO.2 have been measured and among them the hydrated mineral, opal, behaved like an amorphous silica. Neutron irradiated olivine showed a stronger and a broader lOym band in addition to weaker bands towards the longer wavelengths which indicated that atomic damage has been produced. At high fluxes more atomic damage is expected to change the crystalline structure and there by cause changes in the infra-red absorption properties. Extinction measurements were also made for smoke particles of MgO in the infra-red. When the measurements Were made with the particles deposited on substrates, in addition to a very broad surface mode absorption feature around 20ym an extinction maximum was observed typical of the bulk mode at 25ym. Extinction measurements for MgO smoke particles in air also showed similar results. However when the particles were dispersed in a non-absorbing medium, the bulk absorption mode was not observed. This implies that the appearance of the bulk mode is due to clumping. It was also observed that the width of the band reduced significantly with decreasing powder density f in the medium. Hence it is concluded that considerable broadening is due to interactions which is not properly accounted for in the single particle theory.

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