PURSE 1999
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- ItemDesign of the campus network for University of Peradeniya(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Ratnayake, K. B. N.The University of Peradeniya campus network is the largest fiber optic computer network to be established in the country. It is a hierarchical network design based on the multi-layer campus network model having three layers: access layer, distribution layer and the core layer. The technology used for the network is Fast Ethernet/Ethernet with provisions for future upgrades to Gigabit Ethernet. Network switches are used at the core and distribution layers while the access layer uses switches for about 95% of the nodes and shared hubs for the rest. Supported protocols on the network include IP and IPX. Fiber optic cables are used in the links at the core and distribution layers while fiber-optic and copper unshielded twisted pair (UTP) cables are used at the access layer. The access layer, which is at the bottom of the hierarchy consists of the department and building level networks at the various locations within the campus. Layer 2 switches and shared hubs located in the individual buildings and floors and UTP cabling is used to interconnect over 1500 network nodes. In multi-storied and large buildings where it is necessary to use more than one switch, the switches are interconnected using fiber-optic cable. All access layer switches are Ethernet (lOMbps) switches with Fast Ethernet (lOOMbps) uplinks. The distribution layer of the campus network includes the inter-building networks of the faculties of Engineering and Science, Main Library building and the Senate building. Layer 3 Fast Ethernet switches are used for the Engineering and Science faculty networks while Layer 2 Ethernet switches are used elsewhere. Fiber-optic cables are used for interconnections in this layer. The core layer of the campus network consists of a Layer 3 Fast Ethernet switch. The core switch interconnects the distribution layer networks at the faculties of Engineering, Science, Arts, Medicine, Agriculture and Veterinary Science, Dental Science as well as the Senate Building and the Main Library building. The core switch also has a separate link to the common campus network resources in the server farm physically located in the Faculty of Engineering. The server farm includes common campus network resources such as Electronic Mail servers, World Wide Web servers, network management stations, access router connecting the campus network link to the Internet via LEARN (Lanka Educational and Research Network), and the dial-in router which provides access to the campus network through telephone lines. The interconnection medium used in the core layer is fiber-optic cable. Combination cables of Single-mode and Multi-mode optical fiber is used for all locations. Although multi-mode fibers would be sufficient for Fast Ethernet connections to the faculties of Engineering, Science, Agriculture and Veterinary Medicine, Medicine and Dental Sciences, single-mode fibers will be used make future upgrades to Gigabit Ethernet possible. The use of network switches at all the three layers also make it possible to use the Virtual LAN (VLAN) technology to provide location-independent LANs, improved network security and manageability.
- ItemBilayer Actuators(Artificial Muscles) Based on Polypyrrole(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Vidanapathirana, K. P.; Careem, M. A.; Dissanayake, M. A. K. L.; Skaarup, Steen; West, KeldVarious conducting polymers, including polypyrrole (PPy), undergo significant dimensional changes upon electrochemical doping (oxidation) and dedoping (reduction). These changes are linked with the movement of ions and solvents in and out of the polymer during those processes. The conformational changes occurring here are reversible and it has been suggested that this behaviour can be applied in a range of devices such as electrochemically driven mechanical actuators (artificial muscles), micro-structures. These artificial muscles are termed as electrochemomechanical actuators since they work with electric pulse which generate the electrochemical reaction ultimately converted into mechanical energy. In this work, we report about the fabrication of a bilayer artificial muscle with conducting polymer as active layer and a non-conducting polymer as the passive layer. Force measurements were done using the bending beam method, which was used to study the volume changes in the conducting polymer phase in bilayers. Preparation of the artificial muscle was done by electrochemically polymerizing a pyrrole film on a 25µm thick polyimide film ( size 20 x 5 mm) which was coated with 250 Å gold layer to get electrical contacts. Polymerization of pyrrole was done in an aqueous solution containing 0.05 M pyrrole and 0.05 M sodium dodecylbenzenesulfonate (SDBS). Force measurements were done using a microbalance simultaneously with cyclic voltammetry in an aqueous electrolyte of 0.1 M NaCI04. To examine the effect of the film thickness and the polymerization current density on the force, films were prepared with different current densities and with various thicknesses. PPy films were electrochemically deposited on the quartz crystal microbalance electrode to understand the mass change during oxidation and reduction of these films. The force measurement results showed that the films made with higher current densities have larger forces than the films made with lower current densities. They also clearly demonstrated that with the increment of the PPy film thickness, the resultant force showed an increasing trend. When the force. measurements are compared with cyclic voltammetry, it is possible to conclude that the force changes are associated only with main peaks of the cyclic voltammogram. The other interesting feature is that most of the force changes occur in a narrow potential window, which is an advantage in the applications. The results obtained with quartz crystal microbalance showed that during oxidation and reduction 10-20 water molecules co-intercalated to PPy/DBS film with each cation move in and out.
- ItemA design of low cost working model of wind turbine for battery charging purpose(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Obeyesekara, B. R. K.The paper discusses that how to make a cost effective wind battery charger for rural community. Wind battery chargers are becoming popular among the rural communities as they can generate electricity capacity of which can be vary from 50 watts to 250 watts. As it is shown in the studies that power generated by the wind battery charger directly proportionate to area which is swept by the rotor blades of the wind turbine. In other words to increase the power out put, it is necessary to increase the radius of the wind blades. Subsequently increasing the overall size of the wind rotor, which is needed to be optimized with a base function of, cost analysis. Two-blade designs of wind battery chargers are the most cost-effective designs among the wind energy converters for battery charging. And also it is essential to have three-blade design to minimize the vibration to increase the overall plant efficiency relative to Blitz criteria. The faculty of engineering has designed a low cost-wind energy converter for battery charging purpose with the help of computer simulation. Airfoil of the wind blade is selected from NACA airfoil designs. Rated wind speed is taken; as 5 m/s, Furling is 18 m/s. Diameter of the wind blade is 3.2 m. Angle of attack is taken as 17 degrees. Speed ratio of multiplication is 10: J .And Hub of the wind rotor is designed in such away to hold the blades at Constant pitch. Materials for wind blades are used as treated wood planks and components such as hub. housing of multiplicator, cover & rudder of the plant are made out of waste materials of steel and other metals. Cost per l Ou-watt plant is approximately Rs. 48000.00. This is 1/3 rd of the cost reduction of available wind battery chargers. Assemble of wind energy converter for battery charging is fabricated in the faculty of engineering and made several trials to investigate the behavior of the plant according to different wind climates. Below: Assembling process of the wind energy converter.
- ItemComputer based authoring-an electronic book version of the prospectus of the Faculty of Agriculture(University of Peradeniya, Peradeniya, Sri lanka, 1999-11-20) Ariyaratne, A. R.An attempt was made to publish an electronic book version of the Prospectus 1998-2002 of the Faculty of Agriculture, University of Peradeniya. The authoring tool known as AUTHORWARE PROFESSIONAL was used to develop this application. AUTHORWARE PROFESSIONAL 3.5 version is an icon based object oriented programming tool with facilities for hypertext, animations and multimedia applications. The information given in the printed version of the prospectus was rearranged as pages according to the topics. Each page giving specific piece of information is assigned to an icon. The resulting file from structuring of pages and arranging of information was then packaged to produce an executable file. In packaging, the option of Windows 95 and NT gives a file for users who do not have RunA3W application software. The pages containing required information can be accessed or opened by selecting topics given in the Table of Content which appears after introductory pages. Graphics related to the information in various pages have been included. This electronic book can be stored in a single 3.5" HD floppy disk as a compressed file and can be distributed to users instead of printed version. It helps in reducing the use of resources and in cutting down of printing expenses. In addition, the compressed file can be made available as a down loadable file under the faculty web page. The electronic book version of the faculty prospectus is a simple presentation of some of the capabilities available with authoring tools. In applications where use of audio, video, animations and interactions can be incorporated into publications. Therefore, this exercise is expected to create awareness for development of computer based material that can be used in education, training, advertising, etc.
- ItemComparison of the behaviour of electrochemically and chemically synthesized polyaniline(Unviersity of Peradeniya, Peradeniya, Sri Lanka, 1999-11-20) Chandrakanthi, R. L. N.; Kareem, M. A.It has been reported that polyaniline (PANI) can be synthesized by two principal methods; the direct oxidation of aniline by chemical oxidant (PANI-C) or by anodic oxidation on an inert electrode using electrochemical methods (PANI-E). However, the electrochemical method has an advantage of the resulting polymer does not contain contaminants from oxidative agents which are necessary for chemical synthesis. In addition, PANI can be obtained as a conductive film upon the electrode surface in the electrochemical method. The electrochemistry of PANI is more complex than that of other conducting polymers. Here the redox reaction involves the change of complete reduced state to fully oxidized state. The conducting state varies with applied potential and pH of the medium. Therefore conductivity depends on two variables; the degree of oxidation and the degree of protonation. The electrochemically prepared PANI films, which are conducting, can be cycled between oxidized and reduced states. Also thicker film can be prepared and peeled off from the electrode surface to get a free-standing, electrically conducting film. The strong adherence to the inert electrode of PANI has been the basis for detailed electrochemical studies. But the chemically prepared polyaniline doesn't adhere to any of electrode material. Therefore, electrochemical characterization of chemically prepared polyaniline has limitations. In addition, most conductivity measurements reported were made ex-situ with chemically prepared samples. Therefore, it was considered of interest to obtain electrochemical properties and in-situ conductivity of chemically and electrochemically prepared PANI films. In this study, the electrochemical behaviour of chemically and electrochemically synthesized polyaniline films has been investigated in aqueous functionalized acid solutions. Cyclic voltammograms of both films are almost identical. PANI films obtained by these two processes were compared with respect to their conductivity and stability at electrochemical treatment. A steady loss of electro activity occurs for PANI in acidic media during continuous cycling, indicating the total charge storage in PANI film is decreasing with the number of cycles. Conductance results of PANI indicate that there are three electrochemical forms; the reduced form which is insulating, the partially oxidized form which is conducting, and the fully oxidized form that is also insulting.