UAV Parameter Estimation with Gaussian Process Approximations

Unmanned Aerial Vehicles (UAVs) provide an alternative to manned aircraft for risk associated missions and applications where sizing constraints require miniaturized flying platforms. UAVs are currently utilised in an array of applications ranging from civilian research to military battlegrounds. A part of the development process for UAVs includes constructing a flight model. This model can be used for modern flight controller design and to develop high fidelity flight simulators. Furthermore, it also has a role in analysing stability, control and handling qualities of the platform. Developing such a model involves estimating stability and control parameters from flight data. These map the platform's control inputs to its dynamic response. The modeling process is labor intensive and requires coarse approximations. Similarly, models constructed through flight tests are only applicable to a narrow flight envelope and classical system identification approaches require prior knowledge of the model structure, which, in some instances may only be partially known. This thesis attempts to find a solution to these problems by introducing a new system identification method based on dependent Gaussian processes. The new method would allow for high fidelity non-linear flight dynamic models to be constructed through experimental data. The work is divided into two main components. The first part entails the development of an algorithm that captures cross coupling between input parameters, and learns the system stability and control derivatives. The algorithm also captures any dependencies embodied in the outputs. The second part focuses on reducing the heavy computational cost, which is a deterrent to learning the model from large test flight data sets. In addition, it explores the capabilities of the model to capture any non-stationary behavior in the aerodynamic coefficients. A modeling technique was developed that uses an additive sparse model to combine global and local Gaussian processes to learn a multi-output system. Having a combined approximation makes the model suitable for all regions of the flight envelope. In an attempt to capture the global properties, a new sampling method is introduced to gather information about the output correlations. Local properties were captured using a non-stationary covariance function with KD-trees for neighbourhood selection. This makes the model scalable to learn from high dimensional large-scale data sets. The thesis provides both theoretical underpinnings and practical applications of this approach. The theory was tested in simulation on a highly coupled oblique wing aircraft and was demonstrated on a delta-wing UAV platform using real flight data. The results were compared against an alternative parametric model and demonstrated robustness, improved identification of coupling between flight modes, sound ability to provide uncertainty estimates, and potential to be applied to a broader flight envelope

Water scarcity and managing seasonal water crisis: lessons from the Kirindi Oya Project in Sri Lanka

Irrigation management / Water management / Irrigation programs / Irrigated farming / Rain / Crop production / Crop yield / Rice / Case studies / River basins / Catchment areas / Irrigation scheduling / Water allocation / Water use efficiency / Water scarcity / Water shortage / Water demand / Reservoirs / Flow / Farmer participation / Farmer-agency interactions / Farmers' associations / Seasonal variation / Water distribution / Sri Lanka / Kirindi Oya / Ellegala / Lunugamwehera Reservoir

Association Between Job Satisfactions upon the Dimensions of Organizational Citizenship Behaviour: Evidence from Administrative Staff of State Universities in Sri Lanka

Research on job satisfaction has focused on the effect of job satisfaction on organizational citizenship behaviour (OCB) in general. This study explore the association between job satisfaction and dimensions of OCB based on the administrative staff of Sri Lankan state universities in Sri Lanka. The focus of this study was to analyze the effect of job satisfaction on dimensions of organizational citizenship behaviour of administrative staff of 15 state universities in Sri Lanka.  Established questionnaires were used to collect data. A total of 168 questionnaires were used for the analysis. The data was analyzed by SPSS package.. it can be concluded that that job satisfaction predict all the five dimensions of OCB such as altruism, conscientiousness , sportsmanship, courtesy and civic virtue. Keywords: altruism, conscientiousness, courtesy, job satisfaction, organizational citizenship behavior, sportsmanship DOI: 10.7176/EJBM/13-3-03 Publication date: January 31st 202

Geospatial Analysis for Assessing the Socioeconomic Conditions in Resettlement Housing Schemes in Siribopura, Hambantota

This study based on GIS analysis is intended to provide an overview of socioeconomic conditions in the resettlement housing scheme established in Siribopura, Hambantota to rehabilitate displaced persons. Several variables such as monthly income, and house and land values were checked for this purpose. Data were gathered from primary and secondary sources. The primary methods were open discussion and questionnaire survey while secondary methods were relevant documentation and websites. Siribopura, which is located in the Hambantota District was the main resettlement area. Majority of people resettled here are those displaced by the tsunami and certain development projects. The variables were checked using discriminate analysis. As per the results, 62.5% or majority of people in the tsunami resettlement area experience a poor quality of life. In the resettlement area set aside for those displaced by the development projects, the majority (90.6%) lead a quality life. Good income generation is the main reason for that. This study makes an important contribution by comparing the socioeconomic lives of the different groups of people and making an assessment about the resettlement project for the benefit of policy makers. Keywords: Discriminate, Development, Rehabilitation, Resettlement, Housin

UAV Parameter Estimation with Gaussian Process Approximations

Unmanned Aerial Vehicles (UAVs) provide an alternative to manned aircraft for risk associated missions and applications where sizing constraints require miniaturized flying platforms. UAVs are currently utilised in an array of applications ranging from civilian research to military battlegrounds. A part of the development process for UAVs includes constructing a flight model. This model can be used for modern flight controller design and to develop high fidelity flight simulators. Furthermore, it also has a role in analysing stability, control and handling qualities of the platform. Developing such a model involves estimating stability and control parameters from flight data. These map the platform's control inputs to its dynamic response. The modeling process is labor intensive and requires coarse approximations. Similarly, models constructed through flight tests are only applicable to a narrow flight envelope and classical system identification approaches require prior knowledge of the model structure, which, in some instances may only be partially known. This thesis attempts to find a solution to these problems by introducing a new system identification method based on dependent Gaussian processes. The new method would allow for high fidelity non-linear flight dynamic models to be constructed through experimental data. The work is divided into two main components. The first part entails the development of an algorithm that captures cross coupling between input parameters, and learns the system stability and control derivatives. The algorithm also captures any dependencies embodied in the outputs. The second part focuses on reducing the heavy computational cost, which is a deterrent to learning the model from large test flight data sets. In addition, it explores the capabilities of the model to capture any non-stationary behavior in the aerodynamic coefficients. A modeling technique was developed that uses an additive sparse model to combine global and local Gaussian processes to learn a multi-output system. Having a combined approximation makes the model suitable for all regions of the flight envelope. In an attempt to capture the global properties, a new sampling method is introduced to gather information about the output correlations. Local properties were captured using a non-stationary covariance function with KD-trees for neighbourhood selection. This makes the model scalable to learn from high dimensional large-scale data sets. The thesis provides both theoretical underpinnings and practical applications of this approach. The theory was tested in simulation on a highly coupled oblique wing aircraft and was demonstrated on a delta-wing UAV platform using real flight data. The results were compared against an alternative parametric model and demonstrated robustness, improved identification of coupling between flight modes, sound ability to provide uncertainty estimates, and potential to be applied to a broader flight envelope

Optical properties of refractory metal based thin films

There is a growing interest in refractory metal thin films for a range of emerging nanophotonic applications including high temperature plasmonic structures and infrared superconducting single photon detectors. We present a detailed comparison of optical properties for key representative materials in this class (NbN, NbTiN, TiN and MoSi) with texture varying from crystalline to amorphous. NbN, NbTiN and MoSi have been grown in an ultra-high vacuum sputter deposition system. Two different techniques (sputtering and atomic layer deposition) have been employed to deposit TiN. We have carried out variable angle ellipsometric measurements of optical properties from ultraviolet to mid infrared wavelengths. We compare with high resolution transmission electron microscopy analysis of microstructure. Sputter deposited TiN and MoSi have shown the highest optical absorption in the infrared wavelengths relative to NbN, NbTiN or ALD deposited TiN. We have also modelled the performance of a semi-infinite metal air interface as a plasmonic structure with the above mentioned refractory metal based thin films as the plasmonic components. This study has implications in the design of next generation superconducting nanowire single photon detector or plasmonic nanostructure based devices

Effect of Motivation on Organizational Citizenship Behaviour Among Administrative Staff of State Universities in Sri Lanka

This research paper aims to examine the effect of employee motivation on organizational citizenship behaviour among administrative staff of state universities in Sri Lanka. It had been previously reported that motivation had a significant relationship with the organizational citizenship behaviour of employees in various business sectors and industries. In view of the importance of the state university sector as large public sector organizations in Sri Lanka, the focus of this study is to analyze the effect of motivation on organizational citizenship behaviour of administrative staff of 15 state universities in Sri Lanka. An established questionnaires with suitable modification was used to collect data. A total of 178 questionnaires were distributed among the respondents and 168 usable questionnaires were returned, yielding a response rate of 71%. The data was analyzed by SPSS package. The findings shows that both intrinsic motivation and extrinsic motivation have a significant positive effect on organizational citizenship behaviour. Further the study reveled that extrinsic motivation has a positive relationship with organizational citizenship behaviour and which is stronger than the relationship between intrinsic motivation and organizational citizenship relationship among the administrative staff of state universities in Sri Lanka. Keywords: Administrative staff, employee motivation, organizational citizenship behaviour, state universiti

A novel “in-situ” processed gate region on GaN MOS capacitors

This work reports a route to the realisation of GaN metal oxide semiconductor capacitors (MOSCAPs) where the GaN surface has not been exposed to atmosphere. This has been achieved by the deposition of a 5nm SiNx “capping” layer as the final part of the GaN on Si MOSCAP wafer growth to encapsulate the GaN surface, followed by its removal in a “cluster” plasma processing tool, which enables both etching of samples and subsequent dielectric and metal deposition without atmospheric exposure between process steps. Capacitance-voltage hysteresis, A Hysteresis, of 90mV and frequency dispersion, A dispersion, of 150mV were achieved from samples where the SiNx capping layer was etched and then transferred under vacuum prior to atomic layer deposition (ALD) of a 20 nm Al2O3 gate dielectric. These were lower than the previously reported values of 250mV and 350mV respectively for GaN-Al2O3 MOS capacitors where the GaN surface had been exposed to atmosphere. The effects of N2 and H2 plasma treatments after SiNx etch and prior to Al2O3 deposition were examined. Exposure to a 150W N2 plasma for 5 minutes produced a Hysteresis and a Dispersion of 200mV and 250mV respectively, both of which reduced to 60mVafter forming gas annealing (FGA) in 10% H2/90% N2 for 30 minutes at 430oC. The insertion of an ALD grown AlN interlayer between an air exposed GaN surface and the Al2O3 gate dielectric resulted in 50mV a Hysteresis and a Dispersion. However, when the process was transferred to samples that went through the SiNx etch and optimised N2 plasma pretreatment, both a Hysteresis and a Dispersion increased to 500mV. The effect of ALD deposition of a TiN gate metal after Al2O3 gate dielectric was also examined. SiNx capped samples were first etched in the cluster tool before transfer to the ALD chamber in which a 20nm Al2O3 gate dielectric was deposited. This was followed by atomic layer deposition of 20nm TiN gate metal. a Hysteresis and a Dispersion of 550mV and 400mV respectively were obtained. These samples had a capacitance-voltage slope which was 155% higher than otherwise comparable structures with Pt/Au gate metal. In conclusion the reductions in a Hysteresis and a Dispersion achieved in this work during in-situ etching and ALD are encouraging for the realisation of high power GaN devices

Spatial modelling of the householders' perception and assessment of the potentiality to improve the urban green coverage in residential areas: A case study from Issadeen Town Matara, Sri Lanka

Urban forestry has become an important concept in modern city planning for many reasons. Different forms of urban green spaces can be seen in towns as open spaces, tree belts, parks and home gardens. The main objective of this research was to assess the urban green spaces in Issadeen Town, a small residential area in Matara, Sri Lanka. A questionnaire survey was conducted in the study area covering a zone with 200 individual houses. The collected data were entered into a Geographical Information System (GIS) platform, taking one house as the unit of analysis. There was a marked difference between the numbers of trees growing in owner-occupied houses and rental houses. It was also assessed that 11% of the study area had good green cover while 8% of this area had medium level green cover that had the potential to rise to a higher category. The occupants of houses who were living in the high green cover areas stated that they had a positive perception about their environment, especially cooler temperatures. Therefore, they intended to maintain the trees in their housing plots. However, there were other occupants accounting 50.5% of the total, who were not interested or involved in the process of increasing the green cover. This is a matter that the authorities may have to address in future

Design and characterisation of titanium nitride sub-arrays of kinetic inductance detectors for passive terahertz imaging

We report on the investigation of titanium nitride (TiN) thin films deposited via atomic layer deposition (ALD) for microwave kinetic inductance detectors (MKID). Using our in-house ALD process, we have grown a sequence of TiN thin films (thickness 15, 30, 60 nm). The films have been characterised in terms of superconducting transition temperature Tc , sheet resistance Rs and microstructure. We have fabricated test resonator structures and characterised them at a temperature of 300 mK. At 350 GHz, we report an optical noise equivalent power NEPopt≈2.3×10−15 W/√Hz , which is promising for passive terahertz imaging applications