Browsing by Author "Ekanayake, T."

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    Fabrication of an Abrasive Wheel using Garnet Sand
    (Uva Wellassa University of Sri Lanka, 2013) Dayananda, P.S.C.; Ekanayake, T.; Cooray, J.T.
    Economic sand accumulations are found along Eastern and Southern coastal belts of Sri Lanka These mineral sand deposits consist of ilmenite, rutile, zircon, garnet, magnetite, monazite, sillimanite and quartz. Mineral sand separation plants separate minerals using their physical properties such as specific gravity, magnetic properties and conductivity. Garnet is produced as a by-product of this separation process and is removed as a tailing. Southern coastal areas of Sri Lanka such as Tangalle, Ussangoda and Kirinda are known for large scale garnet sand accumulations. Garnet is a mineral with relatively high hardness value. Therefore it can be used as an abrasive material for various applications such as tool sharpening, wood polishing, and metal polishing. Water jet cutting machines use garnet in fine powder form as the abrasive material. There are two types of abrasive materials, namely coated abrasives and bonded abrasives which can be made out of garnet sand. Bonded abrasives are used mainly in abrasive wheels where a suitable bonding material binds the abrasive. These abrasive wheels can be used for removing very fine quantities of material from the work piece. Grinding is a process of removal of particles and surface generation used to shape and finish components made of metals, wood and other materials. Grinding process needs an abrasive product usually a rotating wheel in contact with a work surface. The grinding wheel is composed of abrasive grains held together in a binder. These abrasive grains act as cutting tools and remove very small chips of material from the work piece. Bonded abrasives are used for this sort of applications. Various bonding materials such as vitrified bond, rubber bond, shellac bond, metal bond are used in abrasive wheels. This research was carried out to produce an abrasive wheel using Sri Lankan garnet sands and different types of bonding agents. Performance of each combination was tested.
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    Landmine contaminated area scanning robot
    (Uva Wellassa University of Sri Lanka, 2015) Senevirathne, M.M.G.T.L.; Ekanayake, T.; Wijesooriya, P.N.
    Landmines pose serious threats for post conflict countries like Sri Lanka. There are nearly 120 million landmines all over the world today. Unlike other weapons, landmines are long term killers and function long after a war is over. It kills and maims more than 20,000 civilians per year (World Vision. 2009. About Landmines. United States: World Vision). Clearing the burial mines by human is lethal. Though autonomous mine detecting machines are available, the cost is high and one shortage of the systems is not providing a map of the scanned area. Therefore the percent work aim to design a prototype of an economical autonomous robot which facilitates the mine detecting and map generating of buried places. Methodology The black color marks in a white background were considered as landmines and IR sensors were used as detectors. The complete design is consisting of detectors, carrying vehicle and controlling unit. There are three detectors which are placing in three sides of the robot and each detector consists of five IR sensors. The analog signals of the detector were converted in to digital by using the LM 339 comparator. The separate presets were used to adjust the reference voltage with the comparator. The LED bulbs were placed in front of the sensors to avoid the disturbance of infra-red rays of the sunlight. The detector of the moving side was only activated at a time and other two were deactivated in that time. The robot has to scan the total area and the moving pattern of the robot is the most important part and key feature of the design. It moving on straight lines and moving perpendicular direction without turning. The special wheel was used for this function and the wheels have cylindrical rollers to reduce the friction when it is moving in perpendicular direction. The robot is moving by using the two pairs of wheels. The two pairs wheels arranged in perpendicular direction and driven by gear motors. The L 293 motor drivers were used to control the motors. The 12V 6800mAh li-ion rechargeable battery was used as the power supply of the robot and the power transmission was done by using the L7805 regulators. The powers for the motors were supplied through the two 1000 micro farad capacitors. It avoids the restart of the processor because of the over consumption power of the motors. The regulated power was smooth further and given to the processor. All of the operation was processed by the Arduino Mega at mega 2560 microprocessor. The robot is moving 1m front while scanning the area and doing the serial communication. Then stay 1 second for stable the robot and moving 20cm perpendicular direction and after 1 second delay it is moving back. Then again do the perpendicular movement. The serial communication is occurring while these movements. This process is repeating 5 times again and again. The counter was used to control the repeating times of the cycle. The real time data communication was done by serial communication and data received by a serial terminal. The USB port was functioning as the virtual serial port. The communication port and the baud rate should be same. Baud rate can be set as the requirement. The predefined Matlab application generated the map.