Dissertação (Mestrado em Administração) - Centro Universitário FEI, São Paulo, 2012

Tese de mestr.. Mestre em Tecnologia Multimédia. Faculdade de Engenharia. Universidade do Porto. 2000

Terminating transmission lines at either the source or the load end with a damping resistor is frequently used to improve the signal integrity of clock or control lines on printed circuit boards. While a number of termination variants may produce similar results in regards to signal integrity, the electromagnetic compatibility performance can vary due to different current and voltage distributions along the line. This thesis investigates the impact of transmission line terminations on radiated emissions.

No description available.

This thesis project, focus on the use of Internet and new media as an online communication to improve the caregiver-pupil-school partnership. In particular the usability of the e-service is investigated by studying a real example: the Unikum system as it is used in Tierps municipality. The Unikum e-service is used in many primary schools in different municipalities in Sweden for communication and cooperation between caregivers-pupils and school. The aim is to assess the usability of the Unikum e-service in the particular context of Tierps municipality, find out about the benefits of using it, finding the problems that are there, and also to try to design solutions to improve the usability for the e-service.

Extra High Voltage (EHV) transmission lines are designed to transfer large amount of power from one location to another. The length exposed to the environment is a major reason for occurrence of faults on the lines. A fault on a high voltage transmission line affects the stability of the overall power system, which sometimes leads to permanent damage of the equipment. Relays are developed and installed to protect the lines. The transmission line protection relays, in the industry, are based on the fundamental frequency components of the voltages and currents. These relays need at least one fundamental frequency cycle for performing the protection operation. Voltage and current traveling waves are generated when a fault occurs on the transmission line. The velocity of propagation of traveling waves is finite and the level of the waves decreases with increase in the distance traveled. Information about the fault can be obtained by analyzing the traveling waves. A few traveling wave techniques, which are based on analog signal processing, to protect transmission lines have been proposed in the past. Two digital techniques, which use traveling waves for protecting EHV transmission lines, are proposed in this thesis. The traveling waves are extracted from the modal voltages and currents at the terminals of the transmission line. The techniques identify and locate the fault by using the information contained in the waves. A power system was modeled in the Electromagnetic Transient Direct Current Analysis (EMTDC) and several cases were created by varying different parameters related to the fault, fault type, fault location, fault resistance and fault inception angle. The techniques were implemented in hardware and their performance was tested on data, generated from the EMTDC simulations. Some cases are discussed in the thesis. The performance of the digital techniques for protecting EHV transmission lines using traveling waves was confirmed to be satisfactory. The proposed techniques provide protection at speed and discriminate well between internal and external faults.

No description available.

Extra High Voltage (EHV) transmission lines are designed to transfer large amount of power from one location to another. The length exposed to the environment is a major reason for occurrence of faults on the lines. A fault on a high voltage transmission line affects the stability of the overall power system, which sometimes leads to permanent damage of the equipment. Relays are developed and installed to protect the lines. The transmission line protection relays, in the industry, are based on the fundamental frequency components of the voltages and currents. These relays need at least one fundamental frequency cycle for performing the protection operation. Voltage and current traveling waves are generated when a fault occurs on the transmission line. The velocity of propagation of traveling waves is finite and the level of the waves decreases with increase in the distance traveled. Information about the fault can be obtained by analyzing the traveling waves. A few traveling wave techniques, which are based on analog signal processing, to protect transmission lines have been proposed in the past. Two digital techniques, which use traveling waves for protecting EHV transmission lines, are proposed in this thesis. The traveling waves are extracted from the modal voltages and currents at the terminals of the transmission line. The techniques identify and locate the fault by using the information contained in the waves. A power system was modeled in the Electromagnetic Transient Direct Current Analysis (EMTDC) and several cases were created by varying different parameters related to the fault, fault type, fault location, fault resistance and fault inception angle. The techniques were implemented in hardware and their performance was tested on data, generated from the EMTDC simulations. Some cases are discussed in the thesis. The performance of the digital techniques for protecting EHV transmission lines using traveling waves was confirmed to be satisfactory. The proposed techniques provide protection at speed and discriminate well between internal and external faults.

In this research, the authors aim to identify important dimensions for newly established ventures and the way these dimensions are dealt with. However, this study is limited to small on-line new ventures. In order to achieve this purpose, the authors, after reviewing the literature in the field of e-commerce, have identified five dimensions and have proposed their importance to newly established small internet ventures. Furthermore, the authors tried to check for similarities in the strategies followed by the studied ventures. The dimensions are system qualities, promotion, security, competition and cost. The data was collected from five entrepreneurs who have founded and currently running small online new ventures. The authors found that system qualities, promotion and security were important for all ventures. Whereas, the importance of competition and cost was not shared by all the ventures.

For the requirements of high-speed signal transmission has been increasing. Optical communication system is the way to solve the demands. The 980-nm high-power laser modules are used for optical communication system as the power of the amplifier for long distance communication. The QPSFE is used for coupling between the high-power 980nm laser diodes and the single mode fiber. This research established an on-line inspection system to inspect the fiber endface during the polishing process which is applied on a bare fiber polishing machine. The system we developed is to detect the fiber endface for QPSFE fabrication process. In this paper, we simply use couple charge device (CCD) as a position sensor to detect the grinding situation. The system had been successfully achieved on-inspection purpose, therefore; it will be the key technique toward the automatic bare fiber polishing system.