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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Development and Evaluation of the Ethernet Interface(s) for the Monitoring and Control System of a New Beamforming Radio Telescope

Srinivasan, Abirami 09 September 2010 (has links)
The Long Wavelength Array (LWA) is a large multi-purpose radio telescope, operating in frequencies between 10 and 88 MHz, designed for both long-wavelength astrophysics and ionospheric science. The LWA will eventually consist of 53 "stations", each consisting of 256 pairs of crossed-dipole antennas whose signals are formed into beams. The Monitoring and Control System (MCS), a subsystem of each LWA station, controls the station's subsystems and also monitors their status. This thesis addresses the interface-related features of MCS. The physical interface of the MCS with each subsystem is a Gigabit Ethernet connection and the interface protocol is User Datagram Protocol (UDP). An analysis of the throughput obtained through the interface using UDP is compared to that achieved using Transmission Control Protocol (TCP). It is seen that the throughput with UDP is 15\% better than with TCP, and that UDP is a better choice for the given requirements. Implementation of a new ionospheric calibration scheme requires that the MCS be capable of repointing between astronomical sources on a 5 ms time scale. The rate at which beams can be repointed is analyzed. It is confirmed that MCS is at least 2 orders of magnitude faster than necessary, and is limited by the ethernet network throughput. Python software that facilitates the development and testing of MCS and other subsystems have been developed, and are described. / Master of Science
2

Development of Monitoring and Control System for Switched Reluctance Motor Drive System

Wang, Yung-chin 28 June 2005 (has links)
The reluctance torque of switched reluctance motor could drive the rotor directly. Rotor doesn¡¦t need to be made from permanent magnet and the demagnetization and heat emission problems can be avoided. There are also a lot of advantages, such as the low cost, high efficiency, high stability and high hot emission, make it very attractive to the engineers and researchers. The dual-flange-pole rotor structure will induce non-linear magnetic filed in the air gap between armature and rotor, so the reluctance torque is not easy to handle. The switched reluctance motor is considered hard to control at the early stages of development. In recently years, with the rapid improvement of power electronic devices and microprocessor chips, the engineers and researchers pay more attentions to overcome the difficulties encountered in both the software and hardware step by step. It can now exert the motor¡¦s capability to contend with the inductor motor and the alternating current motor. Furthermore, it is more advantageous than others in the high energy density, high temperature and adverse circumstances. It has obviously caught caused the industry¡¦s attention and the academia's research interests. The work of this is to design and develop a drive system for the switched reluctance motor drive system by using the 32-bit floating point Digital Signal Processor, and operate it in coordination with the peripheral circuits. Finally, the study will integrate the graph control programming to design a monitoring and control system with Man-Machinery Interface (MMI) for monitoring voltage, current and speed of the switched reluctance motor drive system.

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