Master of Philosophy (M.Phil.)

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Browsing Master of Philosophy (M.Phil.) by Author "Karunadasa, JP"

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    item: Thesis-Abstract
    Parameter optimization of CNT production using Sri Lankan graphite by arc discharge methods
    (2014-08-12) Gunasekara, RMSJ; Karunadasa, JP; De Alwis, A; Samaranayake, L
    Since their discovery in 1991 by Iijima, carbon nanotubes have been of great interest. The key advantages of these structures are their electronic, mechanical, optical and chemical characteristics, which open a way to a variety of applications. These properties can even be measured on single nanotubes. For commercial application, large quantities of purified nanotubes are needed. Different types of carbon nanotubes can be produced in various ways. The most common techniques used nowadays are: arc discharge, laser ablation, chemical vapor deposition and flame synthesis. Fundamental and practical nanotube researches have shown possible applications in the fields of energy storage, molecular electronics, nano-mechanical devices, and composite materials. Real applications are still under development. This project is basically focused on arc discharge method of CNT production using Sri Lankan vein graphite. Sri Lankan graphite is unique due to its perfect crystalline structure and the higher as mined purity compared with that of commonly available flake graphite. This type of natural resource is found mainly in Sri Lanka. Detailed study on flake and vein graphite was carried out in this study as one of its objectives. Also SEM and TGA analysis of the multiwall carbon nanotubes are discussed. Special technique for comparing diameters of multiwall wall carbon nanotube was developed by using TGA. Further, the cross section analysis was carried out for the arc scoot to analyze the formation of the nanotubes on the cathode. Another objective here was to identify the optimum parameters for the production of CNT using the arc discharge method. Arcing time, current, chamber inert gas, chamber pressure and the type of the electrode were the variables. Arcing current around 100 A, pressure around 700~900Torr and arcing duration around 60s with helium as the inert gas were the optimize conditions. Key words: Vein Graphite, CNT, MWCNT, Arc discharge, Nanotube
  • Thumbnail Image
    item: Thesis-Abstract
    Parameter optimization of CNT production using Sri Lankan graphite by arc discharge methods
    (2014-08-04) Gunasekara, RMSJ; Karunadasa, JP; De lwis, A; Samaranayake, L
    Since their discovery in 1991 by Iijima, carbon nanotubes have been of great interest. The key advantages of these structures are their electronic, mechanical, optical and chemical characteristics, which open a way to a variety of applications. These properties can even be measured on single nanotubes. For commercial application, large quantities of purified nanotubes are needed. Different types of carbon nanotubes can be produced in various ways. The most common techniques used nowadays are: arc discharge, laser ablation, chemical vapor deposition and flame synthesis. Fundamental and practical nanotube researches have shown possible applications in the fields of energy storage, molecular electronics, nano-mechanical devices, and composite materials. Real applications are still under development. This project is basically focused on arc discharge method of CNT production using Sri Lankan vein graphite. Sri Lankan graphite is unique due to its perfect crystalline structure and the higher as mined purity compared with that of commonly available flake graphite. This type of natural resource is found mainly in Sri Lanka. Detailed study on flake and vein graphite was carried out in this study as one of its objectives. Also SEM and TGA analysis of the multiwall carbon nanotubes are discussed. Special technique for comparing diameters of multiwall wall carbon nanotube was developed by using TGA. Further, the cross section analysis was carried out for the arc scoot to analyze the formation of the nanotubes on the cathode. Another objective here was to identify the optimum parameters for the production of CNT using the arc discharge method. Arcing time, current, chamber inert gas, chamber pressure and the type of the electrode were the variables. Arcing current around 100 A, pressure around 700~900Torr and arcing duration around 60s with helium as the inert gas were the optimize conditions.
  • Thumbnail Image
    item: Thesis-Abstract
    Remote meter reading over power distribution lines
    Gamage, K; Karunadasa, JP; Dias, D; Ranaweera, A
    The thesis presents the development of a simple technique for remote reading of utility meters using the low voltage power distribution network. Remotely reading electricity, gas and water meters have distinct advantages over traditional metering methods. Several communication technologies have been designed and implemented for this purpose using wireless techniques, telephone lines, power transmission and distribution lines. In this study, the last one has been selected as the basis for the development of a remote meter reading system applicable to Sri Lanka. Power line communication over low voltage distribution lines is a cost effective method for data transmission. But it is complex due to large number of branches, tapings, transformers, different line configurations etc., that are present in the distribution network. The main task of this research is to develop suitable techniques for transfer of data over this network. The basic concept of data transmission in this application is the change of voltage and current wave at the supply end and the load end respectively of the power system. A series of current pulses are generated representing the data to be transmitted from the consumer end. Similarly, a series of voltage pulses are generated at the supply end to represent the commands to be sent to the consumer. These current and voltage pulses are superimposed with the line current and the line voltage at the load end and the supply end respectively on the power line signal. The prototype system presented in this thesis shows simulation as well as experimental results relating to the data transmitter, and the software design for the communication subsystem interfacing the meter to the distribution lines. A series of measurements are also carried out to find a suitable time of the day tor the data transmission. Associated problems such as harmonics generated due to the insertion of data and the effects of load changes in the distribution network are also discussed.