﻿ UROP Proceedings 2020-21 – Page 171

# UROP Proceedings 2020-21

School of Engineering Department of Electronic and Computer Engineering 162 Equipment Automation for Remote Experimentation Supervisor: SHAO Qiming / ECE Student: ZAU Ka Ming / CPEG Course: UROP1100, Spring Since I am not at school, what I first did is to watch the video given by the professor. The video mainly talks about the analogue-to-digital converter (ADC) and the digital-to-analogue converter (DAC). For playing the music, it uses the DAC by transforming the electrical signal to analogue signal through loudspeakers. For talking on the phone, it uses the ADC by transforming the analogue signal from the microphone to the digital signal in the form of a radio wave emitting to the station. DAC and ADC are beneficial as there are many analogue things in nature such as temperature, sound, velocity. They are sensitive to noise and difficult to process and store analogue signal, but the digital signal can deal with these problems. However, during the conversion, some analogue signal information may lose because the analogue signal is continuous in time with the continuous amplitude. Therefore, one of the solutions is to control the sampling rate. Suppose the rate is very high; although it can get accurate data, the memory is not enough to support numerous data. If the rate is low, the data may inaccurate due to the aliasing effect. According to the Nyquist Sampling Theorem, the sampling frequency must be at least two times the maximum frequency of the input signal. Another solution is quantization, which assigns a sampled signal value from the discrete set of values. The resolution is how the assigned value close to the actual value is involved. Resolution is that full-scale range or reference voltage divide by two to the power of the number of bits. It means that if the range is extensive, the resolution is low. If the number of bits is large, the resolution is high. There is a tradeoff. To conclude what I have understood while watching the video. I understand the critical parameters of ADC and DAC are the resolution, reference voltage and sampling rate. Rational Design of Magnetic Devices Using Micromagnetic Simulations Supervisor: SHAO Qiming / ECE Student: FONG Cheuk Pan / PHYS Course: UROP3100, Fall Magnetic skyrmion, a type of quasi-particle, is interested by many electronic engineers. It is a great potential for futuristic electronic devices due to its high stability and small size. It can act as an information carrier which is transferred by energy-efficient spin current. Although the velocity and angle of motion are well investigated by many researchers, the deformation of skyrmion is still a difficult problem to understand. This problem leads to another important issue: recoverability of skyrmion size. Skyrmion expands due to magnetic field of materials and spin current. If it cannot return to size close to its initial state, skyrmionbased devices will not function properly, reducing the efficiency of devices. To understand the deformation and the recoverability of skyrmion size, this project is conducted.

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