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item: Thesis-Abstract
An advanced trajectory planner for industrial robot manipulators
(2014-08-22) Munasinghe, SR
This thesis focuses on trajectory planning for industrial robot manipulators. It describes the existing problem of trajectory planning and proposes an appropriate solution. The proposed solution has been devised, implemented and verified for effective functionality. Trajectory planning in this context is the process of planning time-based joint position trajectories for a desired end-effector motion. It needs to consider all relevant constraints of the manipulator and given task specifications; because the final end-effector performance totally depends on the way the joint trajectories are planned. However, most trajectory planners in industrial robotics, even today, have adapted the technique of direct sampling of the desired end-effector motion, and transform such Cartesian positions to joint space using inverse kinematics. Then, the planned joint trajectories are simulated to check if they are realizable within the constraints. It is also inspected if the given task specifications are fulfilled sufficiently. Planned end-effector trajectory is iteratively adjusted by trial-and-error, until an optimum trajectory is obtained. This process has many demerits and it is therefore necessary to develop an appropriate trajectory planning algorithm which has provisions to consider constraints and task specifications in planning end-effector trajectories. It should also be generally applicable to industrial manipulators. Through constant collaboration with Yaskawa Robotics Inc., the major considerations of trajectory planning were identified as being : 1. trajectory allowance, 2. sharp corners, 3. joint acceleration limit, 4. assigned end-effector velocity, 5. Jerk reduction, and 6. delay dynamics. They were considered one-by-one, and techniques were developed to incorporate them into a single trajectory planner. Usually, desired end-effector trajectory is not the optimal trajectory. Therefore, the trajectory planner plans a realizable trajectory with the mentioned considerations above. Realizable trajectory is the optimal trajectory within the given trajectory allowance. At sharp corners, a circular arc is introduced within the trajectory allowance. Joint acceleration limit refers to the power amplifier current rating of the servo controller, and assigned end-effector velocity is the speed specification. End-effector trajectory can be planned using maximum joint acceleration as long as the end-effector remains below the assigned velocity. However, as the end-effector reaches assigned velocity, joint accelerations should be reduced and the speed should be uniformly maintained. Jerk can be reduced by fitting a spline approximation to the planned joint trajectories. Delay dynamics can be compensated by way of pole placement techniques and optimizing the pole by considering servo control input. The proposed trajectory planner was devised and implemented to control an industrial robot manipulator (Performer MK3s) so that a significant improvement of end-effector performance could be demonstrated. The same trajectory planner was rearranged into an autonomous module and incorporated with real-time control. This new implementation was proposed and implemented for supervisory controlled telerobotics applications. It was also applied for welfare robotics applications. Proposed trajectory planner is an off-line process, and it does not require hardware alterations. Thus, it could be conveniently implemented with existing robot manipulator systems.
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
An Urban environment analysis system based on an integrated land- use and transport model
Sathyaprasad IMS
During last several decades the world population continued to grow at an exponential rate, supported mainly by the improved health care facilities all over the world. But most of this growth was confined to relatively fewer number of urban centres. This trend was more obvious in the metropolitan areas of developing countries, where already high natural population increases were backed by increasing migration from rural areas. These intolerably high population growths, however, were not paralleled by the infrastructure provision, and the inevitable outcome was the numerous land-use, transport and environment related problems. The magnitude and the complexity of urban problems in metropolitan areas of developing countries reveal the extent to which these sectors of the metropolis are interrelated. The interrelationships between these sectors are so significant that the roots of the problems in one sector lie in the other sectors as well, and hence should be handled with an integrated approach. Unfortunately, the current institutional set up or the practice of urban planning does not facilitate policy formulation and implementation with such integrated approach. One of the pre-requisites for this much-needed co-ordinated institutional set up and policy planning and implementation practice is an analysis tool that covers all these sectors and the interrelationships among them. An analysis system for integrated policies of land-use, transport and the environment has the objective of providing such an analysis tool. This research focuses mainly on the development of an urban environment analysis system based on an integrated land-use and transport model. This study deals especially with developing metropolises, and those in the Southeast Asia in particular. The objectives of the study are; understanding the present situation and issues of the developing metropolitan areas; the theoretical development of an integrated land-use and transport model; the development of an estimation system of land-use and the environment; and development of a personal computer based analysis system for integrated policies of land-use, transport and the environment. In the beginning, investigation is made on the present situations of developing metropolises with regard to land-use, transport and the environment, in an attempt to understand the issues and their interrelationships, and to decide on the kind of integration between land-use, transport and the environment that best suits the urban areas under discussion. The ways of modelling interactions between land-use and transport are formed considering the dynamics of land-use change and trip characteristics. Land-use and transport interaction is represented in two ways in the contemporary urban models; interaction type where land-use and transport are represented hierarchically connected separate modules, and integrated type where land-use and transport are represented in an organically connected single model framework. The two kinds of integration are discussed and compared. Some urban environmental issues pertinent to the developing metropolises, which have some significance at finer spatial levels than the whole metropolis, are identified and discussed in detail. Most of these issues can be identified as externalities of land-use and transport. The environmental estimation is therefore based on the land-use and transport forecast from the integrated land use and transport model. The interaction between transport and the environment have been the subject of many researches and at present there are many good environment estimation models to forecast transport externalities. But little research has been conducted on the environmental impacts of land-use. Although the environmental impacts of transport are very important, impacts of land-use, such as solid waste and waste water problem, are not at all insignificant, especially in developing metropolises. In the development of the environment estimation system here, interactions between land-use and the environment are discussed. Because the environment estimation model is intended to be used together with an integrated land-use and transport model (which itself is based on an improved version of the RURBAN (Random Utility Rent-Bidding ANalysis) land-use model), it is considered to be necessary to use predicted land-use and transport conditions as inputs, and environment qualities that form explanatory variables for land-use forecast as some of the outputs. In the development of the estimation system of urban land-use and the environment, environmental impacts of land-use are classified into those depend on the change of land-cover and those depend on the intensity of land-use activities. Land cover dependent environmental impacts can be estimated if the land-cover change is known., whereas for other impacts the land-use activity intensity should be known. The basic assumption behind the land cover and emission estimation is that both the land cover and the emission rate of pollutants are related to the land price of the area, which is an output from the land-use model. Land price is used here to represent the intensity of urban activities taking place in a given zone. Out of the zone characteristics predicted by the land-use simulation model, land price represents the intensity of activities most. Since the environmental estimation system is developed to be used together with a land-use simulation model, land price is selected as an index of activity intensity. Land cover does not mean the land-use of an area but the 'spatial composition of land according to the land cover types, such as vegetation, water bodies or built-up areas, as defined in the remote-sensing information'. Whereas emission rates are defined as 'the amount of pollutant emission in a given time from a unit of locator group'. The relationships that relate land cover compositions and emission rates with the land price are developed empirically using base year data of sampled zones. The empirical relationships developed using sampled data are used to forecast the land cover compositions and emission rates of a zone with a known land price. Land cover and emission rates for the forecast year, are used together with land use activity data, derived from the locator composition, and other topographic data, in the environmental simulation model to estimate environmental indicators for different zones. An empirical study is carried out to investigate to what extent is valid the assumption that the emission rates, which represent the intensity of activities in a zone, are related to the land price. Ward-wise solid waste emission data during 1987 and 1990 in the city of Yokohama for residential land-use agree with the assumption. The emission rates and the land price are related with correlation coefficient (R2) of between 0.32 and 0.57. These low correlations are, however, found to be due to the high land prices in two of the wards, which actually have more relationship with the Tokyo metropolis than with Yokohama. The exclusion of these two wards increase the correlation coefficient to 0.95. However, it is found that the per capita pollutant emission relates better with the land price, than the pollutant emission per household, in the case of residential land-use. Example emission equations are derived to estimate solid waste generation from the residential land-use. Another empirical study is carried out to examine the relationship between the land cover composition and the land price. Aerial photographic information and land prices of 1990 in the City of Yokohama are used. Land blocks with varying land prices and belong to different land-uses are used in the analysis. Land cover types are identified visually from the aerial photographs. These land cover compositions correlate with the land price, with correlation coefficients (R2) varying between 0.5 and 0.8. An example set of share curves, which represent the relationships between land price and the composition of land covers, are developed using the data, for different land-use categories. A personal computer based analysis system for integrated policies of land-use, transport and the environment is developed based on the integrated land-use and transport model and the urban environment analysis system mentioned above. The latter part of the study discusses the development of this analysis system on MS-Windows 3.1 environment using Visual BASIC 3.0 as the user interface and FORTRAN language for simulation programs. A brief explanation about the basic features, the facilities available, and the kind of visual output presentation available in the system is also given.
item: Thesis-Full-text
Consolidation analysis of Sri Lankan peaty clay using elasto-viscoplastic theory
(7/16/2011) Karunawardena, WA; Kulathilaka, SAS
is necessary to take these properties into account in order to obtain better predictions from peat consolidation analyses. In the present study, the consolidation behavior of peaty clay found in Sri Lanka is extensively studied using a model based on the elasto-viscoplastic theory. The model can describe the prominent creep behavior of peaty soil as a continuous process. In addition, the model can accommodate the effect of structural degradation on the consolidation process. The analysis takes into account all the main features involved in the peat consolidation process, namely, finite strain, variable permeability, and the effect of secondary compression. Also, it considers the variable compressibility for stage constructed embankments which exert high levels of pressure on the peaty subsoil. The constitutive equations used in the model and the procedure adapted to account for the above-mentioned features of the analysis are described. The constitutive model is based on Perzyna's type viscoplastic theory and the Cambridge elasto-plastic theory combined with empirical evidence. In the finite element formulations, which are based on the finite deformation theory, an updated Lagrangian method is adopted. A description of the material parameters used in the model and the procedures applied to evaluate them, with standard laboratory and field tests, are explained. In addition,. a performance of the model incorporating the original and the modified Cam-clay theory is evaluated by simulating triaxial test results. A comparison shows that with the present definition of the parameters, the original model yields more representative results than the model based on the modified Cam-clay theory. Initially, the capability of the constitutive model to capture the consolidation behavior is verified using the consolidation model test data on peaty clay found in Sri Lanka. It is confirmed that the constitutive model is able to predict the observed creep characteristics and the effect of sample thickness on settlement predictions for the material under consideration. The performance of the model in predicting the consolidation behavior under field conditions is studied using field data on instrumented earth fill constructed on peaty clay. One-dimensional compression is assumed for the peaty clay due to the large plane area of the fill. Separate analyses are carried out by the model considering the infinitesimal strain theory, the finite strain theory, and the finite strain theory together with the effect of structural degradation in order to explore how these features describe the observed field behavior. Analyses reveal that it is necessary to consider finite deformation together with the effect of structural degradation in order to successfully simulate the resultant large strain and the stagnated pore water pressure observed in the field. The construction of road embankments over peat deposits is quite problematic, and thus, it is often done after first improving the properties of the peaty soil through the utilization of appropriate ground-improvement techniques. Understanding the field response of peaty clay during this improvement process is naturally of great importance. A constitutive model is applied to predict the field performance of embankments constructed on peaty clay using different ground-improvement techniques. The back analysis of embankments constructed with the preloading method indicates that the model can be successfully applied to predict both the deformation and the stability of structures constructed on peaty clays. The stability of the embankment during and after construction is verified by investigating the stress-strain characteristics of the subsoil. The model applications used to predict the consolidation behavior of embankments constructed by the preloading method, combined with other ground-improvement techniques, are then discussed. Embankments constructed with prefabricated vertical drains (PVDs) and sand compaction piles (SCPs) are considered, and finite element analyses are carried out in all cases by converting the actual three-dimensional conditions that exist around the drains into simplified two-dimensional plane strain conditions. The field behavior when PVDs are installed in the peaty clay is simulated using the equivalent vertical permeability for the PVD-improved subsoil. In the case of SCPs, a conversion scheme is used to transform the axisymmetric nature of sand columns into equivalent plane strain conditions. A comparison of the predicted results with the field observations shows a reasonable agreement. An analysis of the PVD-improved foundation indicates that the installation of PVDs not only accelerates the rate of consolidation, but influences the deformation pattern of the subsoil due to embankment loading. The analysis also shows that the use of PVDs can significantly increase embankment stability. The model prediction for the SCP-improved foundation reveals that the stiffness and the area replacement ratio used in the conversion scheme play vital roles in predicting the behavior of SCP-improved soft grounds. The observed improvements in the bearing capacity of the subsoil and in the stability of the embankment, brought about by the installation of SCPs, can be simulated by the model.
item: Thesis-Abstract
Cross-bonded cables and analysis of non-linearities
(1972) Lucas JR
The present work investigates the problem of determining transient overvoltages in cross-bonded cable systems, the efficiency of computation by determining short-cut methods and by organising the inverse Fourier transform in a more efficient manner. It also investigates the effect of assuming zero earthing resistances at the major bonding points wherein the analysis is simplified considerably. It improves This work also presents the difficulties encountered in representing non-linear voltage limiting devices when Fourier analysis is used and investigates an alternative method of analysis involving Duhamel's integral.
item: Thesis-Abstract
Degenerating Orr-Sommerfeld Eigenmodes and Development of Three-dimensional Perturbations
(5/24/2011) Shanthini, R
Degeneracies of temporally damped Orr-Sommerfeld eigenmodes are studied primarily for plane Poiseuille flow. The discrete spectrum of the eigenmodes is shown to possess infinitely much degeneracy, each appearing at a certain combination of k (the modulus of resultant wavenumber) and αR (the streamwise wavenumber times the Reynolds number). The streamwise phase velocities of the degeneracies are close to about 2/3of the centreline velocity, and their damping rates decrease with increasing Reynolds number. Interestingly, several degeneracies are operative even at sub-transitional Reynolds number. Degeneracies are found also in water table flow and some of these degeneracies are shown to have the same characteristics and modal structures as those in plane Poiseuille flow. The responses of the degeneracies in plane Poiseuille flow are investigated through the initial-value problem. The initial perturbation field is chosen to be free of normal vorticity, and its velocity component normal to the walls is described by the generalized Orr-Sommerfeld eigenfunction in the normal direction. The subsequent temporal development of this normal velocity is shown to be that of monotonical decay, in the linear regime. Notable initial growth is exhibited by the streamwise velocity of the two-dimensional perturbation flow in case of the least damped degeneracy. Nevertheless, in all cases of the degeneracies investigated, the two-dimensional perturbation flow looses its kinetic energy with increasing time. In the case of a three-dimensional perturbation flow, the span wise variations in the normal velocity induce normal vorticity. The amplitude of the induced vorticity and, hence, that of the streamwise perturbation velocity are shown to grow to significant peak values, before the exponential decay predicted by the linear theory sets in. The amplitude of the induced vorticity is shown to increase also with increasing Reynolds number. The presence of normal vorticity causes the perturbation flow to gain kinetic energy from the basic Poiseuille flow. This gain is so great in cases of the least damped symmetric and anti symmetric degeneracies, that the perturbation flow overcomes its energy loss due to viscous dissipation and exhibits significant initial growth of its kinetic energy, at crucial Reynolds numbers such as the transitional one. These growths, according to the linear theory, do not influence the normal velocity that is monotonically decaying with time. It is shown, however, that these growths are to be followed by nonlinear equations at about the transitional Reynolds number. It is also shown that describing the solution of the nonlinear system as waves travelling in one single oblique direction does not change the monotonous behaviour of the normal velocity. Key words: degeneracy, double eigenvalue, Orr-Sornmerfeld equation, direct resonance, stability, plane Poiseuille flow, water table flow, initial-value problem, three-dimensionality, vortex stretching, induced vorticity, nonlinearity, Reynolds stress, perturbation energy.
item: Thesis-Abstract
The Development of a structure for the design of hazard audits
(2014-07-07) Dester, WS
Hazard auditing, which is a formal, systematic, critical examination of a situation or set of circumstances to identify hazards, is fundamental to hazard management. Auditing is facilitated by "an audit" that details activities, procedures, systems and artefacts, where hazards might be identified. This thesis describes the development of a structure, in the form of a hierarchy, that can be used in the design of hazard audits. An examination of systems such as manufacturing and process plants, for hazards, is usually undertaken by examining the subsystems, (i.e. activities, systems, and procedures). Existing audits therefore, tend to be specific, as for example, audits of unsafe acts, unsafe conditions, technical functioning of materials and machinery, management. This type of audit restricts the examination to a closed system within observable and well described physical and organisational boundaries. It is argued in this thesis that examinations for hazards should go beyond this closed system and also look for hazards within the larger systems of society and industry. An examination of hazards can be seen as a search for evidence of proneness to failure. The hierarchy developed in this research focuses on hazard auditing for a construction project. Construction, which is associated with the construction industry, is only one phase in a larger system, the project, which encompasses development, use, and withdrawal from use. It is argued that evidence of proneness to failure of a construction project may be found in these systems, (project and industry), in the larger system of a social environment, and in the subsystems that are part of a construction project. These hazards are described in terms cf concepts, and presented in the form of a hierarchy that indicates inter-dependencies between concepts. This hierarchy is a basic structure to be used in the design of hazard audits. The concepts incorporated into the hierarchy are discussed and described in terms of their potential to provide evidence of proneness to failure. Sections of hierarchy are built up and presented at appropriate positions in the thesis. It is proposed that this approach to hazard auditing will allow for flexibility in dealing with specific situations, yet provide for the identification of hazards that can exist and develop outside of those situations. It is suggested that such an approach should be regarded as a specialist activity of hazard management. Further, it is argued that the activity of hazard engineering should be recognized as a separate discipline within its own right.
item: Thesis-Abstract
Digital library of statistical information for science and technology personnel in Sri Lanka
(2014-08-07) Gamage, RCG
Digital Library is a popular concept in the West. It is considered as an efficient tool for improving access to information. This study has made an attempt to justify the need for a digital library on Statistical Information for Science and Technology Personnel in Sri Lanka. The possibility for a Digital Library of Statistical Information to be sustainable was justified with the data on availability of infrastructure and enthusiasm of prospective patrons. At the same time, actual user needs and preferred presentation formats were identified. The research tool was a survey. Seventy five per cent of the sample think statistical information is very significant in their routine work. But they believe that such information is difficult to find. It was revealed that Internet is 387 times efficient in retrieving information than Books. This demonstrates the possibility of building up an Internet based information source. Seventy nine per cent of the sample had access to Internet at office. Therefore having access to an Internet based Digital Library is not a problem for Science and Technology Personnel in Sri Lanka. More information related to agriculture should be included. The first level of data should be presented as abstracts. Science and Technology Personnel in Sri Lanka think of Digital Libraries positively. They are even willing to pay for information. Thus, a Digital Library Project would find its audience in Sri Lanka.
item: Thesis-Abstract
Factors affecting query formulation in Web information search
(2014-06-13) Kumara, ADB
The World Wide Web, which is exponentially growing daily, is also known to be the richest source of information. The Web is universally adopted by university academic communities as a part of their information seeking motivated by a wide variety of needs including academic, professional, personal or entertainment etc. The ability to search and retrieve information from the Web effectively and efficiently is a challenge as current search tools retrieve too many documents of which only a small fraction is relevant to the user query. Studies have revealed that well formulated queries are one of best solutions for this challenge. This study is an attempt to find out the factors affecting query formulation on Web information searching of university academic community. The study is compiled with data gathered from questionnaires of 255 undergraduate students, 107 postgraduate students, 40 NDT students and 30 teaching faculty members. The total response rate is 98.63%. The results indicate Web experience, topic familiarity and search strategies as the identified factors affecting query formulation. The average number of stop words per query decreases when Web used experience increases and the time spent to formulate a query increases when the Web used experience increases. Also, the time spent per query decreases with a familiar topic and he/she desire to use synonyms. Recommendations were made to conduct training programs on available Web information sources/resources and Web searching strategies.
item: Thesis-Abstract
A Framework for providing a lifelong social security system for the operational workforce in the construction Industry in Sri Lanka
Wijewickreme, SP; Ekanayaka, LL; Pathirage, CP; Egbu, C
Construction is a projectised industry. One of the important resource requirements for construction projects is the availability of an operational workforce for its physical production. Hence, the operational workforce is a critical deciding factor in the success and failure of construction projects. The construction sector in Sri Lanka is suffering from a shortage of a required operational workforce for its physical operations even though the unemployment rate in Sri Lanka is about 5.2%. Research has further highlighted that “work” and “pay” are only the surface factors, hiding underneath them (similar to an iceberg) are a multitude of different problems and the psychological needs of the workers. In addition to the shortage, there is a lack of an organised structure for human resources, which delivers time, cost and quality related behavioural constraints within the construction industry of Sri Lanka since circa the 1980’s. The aim of the research is to develop a sustainable framework for a lifelong social security system for the operational workforce of the construction industry in Sri Lanka without increasing the prevailing construction costs. The hypothesis is the minimising of resource wastages and behavioural impacts of current practices and the introduction a secured future life through a new system of lifelong social security [PR/SS] for the operational workforce. It is anticipated that the finances required for providing a social security system can be salvaged from the recovery values of material and time wastages and the demand and supply impacts generated as repercussions from the behavioural practices of the current operational workforce. The research instruments used for gathering primary and secondary data for evaluating the financial impacts of behavioural constraints were a questionnaire survey and audited financial statements. About 400 questionnaires (That were premeditated to calculate the monetary impacts of the social behaviors of the construction operatives via ‘degree of importance’ and ‘relative important index’) were distributed to higher management of contracting organisations in Sri Lanka. A further request was made to the contracting organisations to provide audited statements for the past five years. From the research, it was identified that the unavailability of a human resources structure is a major constraint for the construction industry in Sri Lanka. Salvaged finances that could derive from the removal of the transitional layers of risk multiplication and the removal of the behavioural constraints of the construction operatives are sufficient to finance a lifelong social security system for themselves. Based on the research findings, framework for the Building Forces of Sri Lanka [BFSL] was developed to overcome from the interim thinking pattern of the current construction operatives. In the current system, contracting organisations are not capable of providing the required training for the operatives. With the implementation of BFSL alongside the strong intervention from statutory organisations, a trained operational workforce can be developed to face any situation within the construction arena in Sri Lanka.
item: Thesis-Abstract
The growth of buddhist monastic institutions in Sri Lanka from Brahmi inscriptions :
(2001) Dias M; Reynolds CHB
The propagation of Buddhism in Sri Lanka in the third century B.C. as witnessed by the lithic records and the chronicles was due to the efforts of the Buddhist monks who spread Theravada or the orthodox tradition of the religion in the first few centuries. Its spread went parallel wtith the growth of monastic institutions in the island. At first the patronage extended by the kings and the people towards the Buddhist monks was to safe-guard the religion. They were endowed with dwellings and requisites for their maintenance. To make them self-sufficient the monks were endowed with permanent and valuable gifts consisting of land, tanks, revenue from taxes and so forth. When these endowments were made, the monks became landholders and gained a role of leadership in society. On the one hand, the relationship with the masses made thc Saitgha an institution which dominated society in its own way. On the other, it became a major factor to check the royal power. The monks generally regarded themselves as having a two-fold task; striving for their own salvation and preaching the Dhamma to lead others to find their salvation. It was the scholar and the preacher in them that were useful to society. Buddhism was flourishing in.the entire island by the second century A.D. Even before that dissensions among members of the Sattgha were visible in the premiere establishments such as Mahavihara and Abhayagirivihara. Some individuals struggled for power and tried to gain favours from the kings. By about the third century A.D. new trends of thought in Buddhism, coming from the subcontinent of India, were making headway in the island. By contact with these new movements, the monks of the Abhayagirivihara were becoming liberal in their views. The new schools of thought such as Vaitulyavada, described as heresies in the chronicles, divided them into sects. These schools of new thought had the backing of some kings though the Mahavihara vehemently opposed them. By about the fourth century, there were three fraternities, namely, Mahavihara, Abhayagiri and Jetavana. The inscriptions and the chronicles bear clear evidence to the manifestation of Mahayana ideals such as the Bodhisattva worship. The sixth and seventh century inscriptions attach great importance to the merit-making rituals that accompanied them. Here we find the Safigha in the role of the priest invoking blessings on the masses and becoming an indispensable figure in society.
item: Report-Full-text
Guidelines to office system in the university
Sadique, ALJ
There is no guidelines available in the Universities to perform the office administration effectively and efficiently. Methodology adopted in the past in a University differs from the other and depends on the administrator who administer. This report provides ways and means to streamline the above past practice. This report describes the basic understanding of principals of office system and the relevance to efficient and effective University administration. The aims of this report are to provide basic skills and techniques in the office system for achieving better performance and to make aware of various practice of office system in the University to enable University administrators and clerical staffs to develop a brodened perspective of their role in the University administration.
item: Thesis-Abstract
Health aspects of traditional housing in Bali
(1977) Cabot, GM
Man is made in the image of his creator, and in his turn becomes the creator of his immediate environment, again in his own image. Thus do the Balinese view their own existence and their role in shaping the tiny morsel of the physical world allotted to their care. Their success as caretakers will affect their crops, their families1 safety and well-being, wealth, happiness, state of mind, and their physical health. The guidelines and consequences of alternative methods in manipulation of the living environment are detailed in ancient texts in the classical Xtiwi language, which have been preserved and recopied from the times of the Hindu Javanese Kingdoms until the present. These texts allow us to see the insights which the Balinese have into the interrelationships between themselves as physical and spiritual beings, their surroundings, and the physiology of the perceivable universe.
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
Hyperbolic paraboloid shell roofs
(2014-04-10) Mathai, AC
Of recent years,hyperbolic paraboloid doubly curved surface, has been used extensively in construction. It makes efficient ur.e of materials by relying on form or shape for strength rather than on mass. The simplicity of its structural action and its inherent beauty make it possible to achieve aesthetically pleasing structures of imposing proportions. One of the features of the hyperbolic paraboloid form, which appeals to the architect, is the many ways in which this warped surface can be combined to achieve completely dissimilar striking effects. The groined vault, the inverted umbrella and the saddle shape vault are all popular examples of the different appearances which can be achieved with basically the same
item: Thesis-Abstract
Internet and its Impact on University Libraries: A Case Study at University of Moratuwa
(2014-08-19) Seneviratne, TM
The Internet, networks of networks, has revolutionized the way one can access the information and provide numerous opportunities to the field of library and information science in providing information services easily, timely and appropriately to the users. Therefore the Internet has an impact on library and information services. This case study was carried out at University of Moratuwa to find out the impact of Internet on university libraries. The study aimed to analyze trends in Internet usage in terms of major user categories, Internet usage patterns, Internet information resources, services, Internet tools and technologies and their impact on university library. The focus of this study was based on three hypotheses; 1) Since Internet is regarded as an information resource and academic staff and students of the university can freely access it, Internet has significantly reduced the university library usage. 2) As an information resource; Internet users had more favourable attitude towards the characteristics and features of the Internet than the university library. 3) Majority of the Internet users, irrespective of the user category view, University of Moratuwa, Library web site in fulfilling their information needs. The research sample of the study consisted of 50% of the population of academic staff members, 25% of the postgraduate students, 10% of the undergraduate students and 10% of National Diploma in Technology students and amounted to 518. The study received 83.4% response rate. According to the results, two hypotheses found to be true. And it was revealed that the Internet has been recognized as source of information by all the user categories of University of Moratuwa, Library and some or other way Internet has reduced the university library usage. To add up, all user categories had favourable attitudes towards the Internet as a resource of information than the university library. But Internet tools, technologies and services are not optimally used by all the user categories. Even the facilities and features of University of Moratuwa, Library web site has not been utilized as expected. Therefore, university libraries have to taken an advantage of Internet as a source of information and must play a pro-active role in utilizing its tools, technologies and services to enhance access to the information with respect teaching, learning and research activities of the university without diminishing its status in the academic
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
An Investigation of the needs and needs satisfaction of the aged in institutional care
(2014-08-07) Senarath, DCH; ELDERLY-Institutional care; ELDERLY-Sri Lanka
The issues associated with an increasing population of the aged have received much attention in recent years in Sri Lanka as well as in many other countries. The importance of these issues has been highlighted by setting up an International Elders Day, which is 01st of October, and an International Elders' Year from 01s l October 1998 to 30I h September 1999. A major part of the investigation described in this dissertation was carried out during the International Elders' Year. In the Sri Lankan context, several factors of comparatively recent origin have contributed to the magnitude of the problem that exists today. The technological and scientific advances particularly in the context of preventive and curative medicine have resulted in enhanced longevity. Successes in education in reproductive health and family planning have resulted in decreased birth rates. These two factors in combination have given rise to a larger proportion of the aged. The competitiveness of society as a result of the diminishing of natural resources and the longing for comfortable life styles have resulted in diminishing of the ability of family members to care for the aged within the family. This situation causes increasingly heavy burdens on society in caring for the aged. In this context, it is very pertinent to examine- the problems of the aged from many angles. The present study focuses on the needs of the aged and the extent to which they are satisfied in Sri Lanka.
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Long waves on water of variable depth
(5/24/2011) Gunasekara, MM
This dissertation is mainly a review of some of the work done by various authors on the long wave (shallow water) approximation and its applications to different problems. Shallow water wave equations are derived which are identical with Stoker's equations but the method of derivation is slightly different. The method of characteristics is used in solving the differential equations governing the shallow water wave theory. The climbing and breaking of waves on sloping beaches is discussed. After the derivation of the transport equations for the discontinuities that can exist across a characteristic an equation is obtained for the time and hence the distance of breaking. A simple explanation of the formation of a bore in a sloping stream is given here. The climb of a bore on a beach of uniform and non-uniform slope is also discussed briefly because of its close resemblance to non-uniform shock propagation in gas dynamics. The notion of tsunami waves and the use of shallow water wave theory in the study of the numerical simulation of realistic tsunamis is also discussed briefly.
item: Thesis-Abstract
Long waves on water of variable depth
(6/21/2011) Gunasekara, MM
This dissertation is mainly a review of some of the work done .by various authors on the long wave (shallow water) approximation and its applications to different problems. Shallow water wave equations are derived which are identical with Stoker's equations but the method of derivation is slightly different. The method of characteristics is used in solving the differential equations governing the shallow water wave theory. The climbing and breaking of waves on sloping beaches is discussed. After the derivation of the transport equations for the discontinuities that can exist across a characteristic an equation is obtained for the time and hence the distance of breaking. A simple explanation of the formation of a bore in a sloping stream is given here. The climb of a bore on a beach of uniform and non-uniform slope is also discussed briefly because of its close resemblance to non-uniform shock propagation in gas dynamics. The notion of tsunami waves and the use of shallow water wave theory in the study of the numerical simulation of realistic tsunamis is also discussed briefly.

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