228 research outputs found
YIELD ENGINEERING AND IMPROVEMENT ON SEMICONDUCTOR DEVICES
No full textMaster'sMASTER OF SCIENCE IN ADVANCED MATERIALS FOR MICRO- & NANO- SYSTEMSDissertation Advisor: 1. Prof. Wong Chee Cheong. Chartered Semiconductor Manufacturing Project Supervisor: 1. Dr. Nace Layad
NIE Family Day 2014 (3 Oct 2014)
No full textThe Staff Welfare Recreation Fund Committee (SWRFC) Organizing Committee of Family Day. Back row, from left: Lee Li Lian Val (NSSE), Nenny Noorman (LIBRIS), Kristina Burgetova (PS), Ho Yen Yen Rebecca (NSSE), Low Li Jia (OAAS), Soo Li Mei Johannah (NSSE), Lim-Ang Ah Buan (NSSE) and Stevenson-Yong Mary Magdalene (NSSE). Front row, from left: Lionel Lim Chee Sin (NSSE), Foo Meng Wei (GPL), Chua Wee Ann (OTE) and Lum Hon Peng (CSC)
Wireless Communication Networks for Gas Turbine Engine Testing
No full textA new trend in the field of Aeronautical Engine Health Monitoring is the implementation of wireless sensor networks (WSNs) for data acquisition and condition monitoring to partially replace heavy and complex wiring harnesses, which limit the versatility of the monitoring process as well as creating practical deployment issues. Using wireless technologies instead of fixed wiring will fuel opportunities for reduced cabling, faster sensor and network deployment, increased data acquisition flexibility and reduced cable maintenance costs. However, embedding wireless technology into an aero engine (even in the ground testing application considered here) presents some very significant challenges, e.g. a harsh environment with a complex RF transmission environment, high sensor density and high data-rate. In this paper we discuss the results of the Wireless Data Acquisition in Gas Turbine Engine Testing (WIDAGATE) project, which aimed to design and simulate such a network to estimate network performance and de-risk the wireless techniques before the deployment
Strain-tuning of periodic optical devices : tunable gratings and photonic crystals
No full textThesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003.Includes bibliographical references (p. [161]-173).This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.The advancement of micro- and nano-scale optical devices has heralded micromirrors, semiconductor micro- and nano-lasers, and photonic crystals, among many. Broadly defined with the field of microphotonics and microelectromechanical systems, these innovations have targeted applications in integrated photonic chips and optical telecommunications. To further advance the state-of-the-art, dynamically tunable devices are required not only for demand-based reconfiguration of the optical response, but also for compensation to external disturbances and tight device fabrication tolerances. In this thesis, specific implementations of strain-tunability in two photonic devices will be discussed: the fundamental diffractive grating element, and a photonic band gap microcavity waveguide. For the first part, we demonstrate high-resolution analog tunability in microscale diffractive optics. The design concept consists of a diffractive grating defined onto a piezoelectric-driven deformable membrane, microfabricated through a combination of surface and bulk micromachining. The grating is strain-tuned through actuation of high-quality thin-film piezoelectric actuators. Device characterization shows grating period tunability on the order of a nanometer, limited by measurement uncertainty and noise. The results are in good agreement with analytical theory and numerical models, and present immediate implications in research and industry. For the second part, we generalize the piezoelectric strain-tunable membrane platform for strain-tuning of a silicon photonic band gap microcavity waveguide. Additional motivation for this strain-tuning approach in silicon photonic crystals lies in:(cont.) (a) the virtual absence of electro-optic effects in silicon, and (b) the ability to achieve tuning with low power requirements through piezoelectric actuation. Compared to current thermo-optics methods, piezoelectric actuation affords faster and more localized tuning in high-density integrated optics. The small-strain perturbation on the optical resonance is analyzed through perturbation theory on unperturbed full 3D finite-difference time-domain numerical models. Device fabrication involves X-ray nanolithography and multi-scale integration of micro- and nano-fabrication methods. Experimental characterization achieved dynamically-tunable resonances with 1.54 nm tunable range (at 1.55 Mum optical wavelengths), in good agreement with theory. This is the first demonstration of strain tunability in photonic crystals and contributes to the development of smart micro- and nano-scale photonics.by Chee Wei Wong.Sc.D
Direct metal-to-metal thermocompression bonding studies
No full text171 p.Three-dimensional integration, which involves stacking devices vertically, promises several attractive benefits such as high functionality, performance and low system power consumption due to shorter signal delays with the elimination of long wires. One of the common bonding techniques used is metal fhermocompression bonding. The greatest stumbling block for using this technique is the need for high bonding temperature and/or pressure to create strong and reliable bonds. This thesis begins with a study on how temperature and pressure affect bonding characteristics and the mechanical integrity of direct gold joints. One important finding of these experiments is the identification of a critical temperature and pressure below which no bonds can be formed. The criteria for bonding to occur include the removal of surface barrier film between contacting sites through sufficient interfacial mechanical and chemical actions. Freshly exposed surfaces are thus activated thermally, leading to an increase in bond strength. Higher bonding pressure increases bond strength but to a maximum. With further geometrical measurements and fracture analysis, the bonding mechanism is elucidated. This thesis also presents, for the first time, a method to lower the required bonding temperature in gold thermocompression bonded joints with the help of self-assembled monolayers [SAMs]. A comparative study on alkanethiols of various chain lengths in influencing its bondability at several temperatures is evaluated.DOCTOR OF PHILOSOPHY (MSE
Development of electrode materials for energy storage in supercapacitor application
No full textThere is a growing interest in developing supercapacitors for the use of energy storage. The current challenge is to develop a supercapacitor that has an energy capacity comparable to traditional batteries, while retaining the fast charging benefits of capacitors. The objective of this research project is to develop a novel ternary composite electrode material made up of conducting polymer, metal oxide and graphene, which can give high capacitance and very high energy density. Polyaniline is the common choice of material for developing conducting polymers due to its large capacitance, ease of production, and low cost. As much research has been done on polyaniline, this research project aims to explore further by working on 2-(Methylthio)aniline, a derivative of polyaniline, in hopes of achieving better results as compared to polyaniline. The conducting polymer made from 2-(Methylthio)aniline was ultimately used in developing a ternary supercapacitor composite and tested for its capacitance as well as power density.MECHANICAL ENGINEERIN
Sub-fm/Hz(1/2) displacement measurement on MgF2 whispering gallery mode microcavity
No full textWe present sub-fm/Hz(1/2) displacement measurement on the MgF2 whispering gallery mode microcavity. We analyze power spectral density of the displacement from 1 Hz to 100 kHz of the Fourier offset frequency. (C) 2020 The Author(s
Protocol design of a slot allocation scheme for persistence-reservation-based IEEE 802.16d mesh networks
No full textSynthesis And Activity Studies Of Novel Dispiro Pyrrolidine Compounds As Potential Antimycobacterial Agents
No full textSekumpulan dispiro pirolidina yang mengandungi lima puluh dua sebatian telah berjaya disintesis dengan menggunakan penambahan siklo 1,3 dwikutub. Tindak balas ini terbukti sangat regioselektif, menghasilkan satu set regioisomer
sahaja sebagai produk.
A mini library of fifty two highly functionalized dispiro pyrrolidines were synthesized successfully using 1,3-dipolar cycloaddition. This reaction is proved to
be highly regioselective, giving only one set of regioisomer as product
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