UM OAPS - Outstanding academic Papers by Students
http://oaps.umac.mo:80
The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.2017-08-18T11:03:03ZA 12-Bit Reference Error Calibrated SAR ADC
http://oaps.umac.mo/handle/10692.1/143
Title: A 12-Bit Reference Error Calibrated SAR ADC
Abstract: Analog-to-digital converter (ADC) functions as a bridge between the analog and digital worlds. It has wide applications such as cell phones, cameras and high-definition televisions. Due to the development of CMOS technology downscaling, the channel length and the supply voltage of the device shrink significantly, hence the digital circuit, which is less sensitive to noise, benefits in the aspects of speed and power consumption. Successive-approximation-register (SAR) ADC becomes popular recently thanks to its digital assisted nature. It consists of capacitive digital-to-analog converter (DAC), dynamic comparator and SAR logic. The conversion of the SAR ADC relies on the DAC to perform the binary searched feedback between the input signal and the reference voltage, while for high-speed design the DAC settling time becomes the major limitation in speed and accuracy. Moreover, the package inductive bonding generating switching noise due to current transient of the DAC causes reference voltage variations that further degrade the conversion accuracy. This project presents a 12-bit 130-MS/s reference calibrated SAR ADC in 65-nm CMOS using proposed dynamic capacitive-error-compensation (DCEC) technique to suppress the DAC settling and the reference errors in the most-significant-bits (MSBs) transitions. These signal-dependent errors are estimated and compensated in analog domain. The solution costs less implementation effort and does not sacrifice the dynamic range of the conversion. In addition, the comparisons between the proposed method and the existing solutions are analyzed in detail and the corresponding mathematical model in MATLAB is provided. The DCEC scheme was implemented in a 130-MS/s 12-bit SAR ADC with only 3-pF reference decoupling capacitance. The post-layout simulation result shows that the proposed solution can effectively improve the SNDR from 52 dB to 65 dB with only 4 mW power dissipation, achieving the Figure-of-Merit (FoM) of 21 fJ/conv.step.2015-01-01T00:00:00ZComparison between the Non-Adaptive and Adaptive Bias Correction on Hourly PM Forecasts of the Deterministic Model WRF-CAMx
http://oaps.umac.mo/handle/10692.1/136
Title: Comparison between the Non-Adaptive and Adaptive Bias Correction on Hourly PM Forecasts of the Deterministic Model WRF-CAMx
Authors: YANG, HUI (楊惠)
Abstract: This Final Year Project mainly focuses on the comparison between two bias correction approaches carried out on forecasts of Particulate Matters (PM) within Pearl River Delta Region that were simulated by the deterministic air quality forecasting model WRF-CAMx. The two approaches, namely non-adaptive (or offline) bias correction and adaptive (or online) bias correction, were constructed under the ordinary least squares principle and the Kalman filter algorithm, respectively, as implemented by MATLAB. The obtained corrected data were then fitted into line charts and scatter plots for graphical comparison; also, they were processed and shown as indicators for numerical evaluations of the correction model’s performance.
The results verified the efficacy of both correction methods, while highlighted better performances of the adaptive (online) correction model, which suggests that the WRF-CAMx system may be time-varying. Data also shows that WRF-CAMx tends underestimate the PM concentration within the study period (January, 2014).2017-01-01T00:00:00ZAnalysis of Some Geometrically Nonlinear Catenary Structures
http://oaps.umac.mo/handle/10692.1/135
Title: Analysis of Some Geometrically Nonlinear Catenary Structures
Authors: REN, CHENJIE (任臣捷)
Abstract: The behavior of a cable truss is generally considered as being analytically nonlinear. This thesis follows Irvine’s procedures to derive the nonlinear and linear analytical solutions of cable truss systems, taking into account the geometry, pretension, boundary condition and temperature difference. After the final closed-form solution is achieved, the resultant increase in horizontal component of cable force in both top and bottom chords of a cable truss can be solved correspondingly, with which the deflection at midspan of the cable truss can be further figured out. This kind of work is done by transforming the solution into computer program. With the help of numerical method, it is found there is obvious difference between the results of nonlinear solution and linear solution. Besides, 10 different cases are assumed and solved to see the effect that parameters related to the solutions will have on the difference of the result from those two kinds of approaches, in which the considered parameters include the span-to-sag ratio, span-to-camber ratio, pretension in chords and temperature difference in both top and bottom chords. It is found the difference of resultant horizontal force in bottom chord for a biconcave cable truss from the two approaches and the difference of resultant force in top chord for a biconvex cable truss from the two approaches are most sensitive to the change of any of the considered parameters. However, it should be noted all the results and the conclusions are obtained within a limited range.2017-01-01T00:00:00ZDistortional and Warping Analysis of Rectangular Thin-walled Closed Beams
http://oaps.umac.mo/handle/10692.1/134
Title: Distortional and Warping Analysis of Rectangular Thin-walled Closed Beams
Authors: NG, CHI KIN (吳子健)
Abstract: The purpose of this project is to present a warping and distortional analysis of thin-walled box beams. In this project, the behavior of thin-walled box beams in rectangular shape under different loadings and boundary conditions has been studied. The torsional warping and distortion deformations were predicted using pre-assigned functions which formed a stiffness matrix equation to solve the one-dimensional problem using a standard two-node displacement-based C0-continous finite element approach. A computer program was developed using Fortran Language to carry out the numerical analysis and which was compared with the results using existing Finite Element Method Software – Abaqus shell models. The result was also compared with the work by other researchers to check its accuracy and validity.2017-01-01T00:00:00Z