Mechanical Engineering Commons^™

Measurements Of Methyl Radicals And Temperatures By Using Coherent Microwave Rayleigh Scattering From Resonance Enhanced Multiphoton Ionization, Yue Wu

Doctoral Dissertations

This thesis includes two main parts: (I) The CH₃[methyl radical] detection in methane/air flames and (II) the rotational temperature measurement of O₂[molecular oxygen] in a variety of environments by using coherent microwave Rayleigh scattering from resonance enhanced multiphoton ionization (Radar REMPI).

In first the part, from Chapter I to Chapter III, the methyl radical detection and quantitative measurements have been conducted in hydrocarbon flame with one-dimensional and two-dimensional spatial-resolved concentration distribution. Due to the proximity of the argon resonance state (4+1 REMPI by 332.5 nm) with the CH₃ state (2+1 REMPI by 333.6 nm), in …

Temperature Measurement Using Infrared Spectral Band Emissions From H2o, Daniel Jared Ellis

Theses and Dissertations

Currently there is no known method for accurately measuring the temperature of the gas phase of combustion products within a solid fuel flame. The industry standard is a suction pyrometer and thermocouple which is intrusive, both spatially and temporally averaging, and difficult to use. In this work a new method utilizing the spectral emission from water vapor is investigated through modeling and experimental measurements. This method was demonstrated along a 0.75m line of sight, averaged over 1 minute in the products of a natural gas flame but has the potential to produce a spatial resolution on the order of 5 …

Fatigue Life Estimation Of Modified Railroad Bearing Adapters For Onboard Monitoring Applications, Alexis Trevino, Arturo A. Fuentes, Constantine Tarawneh, Joseph Montalvo

Mechanical Engineering Faculty Publications and Presentations

This paper presents a study of the fatigue life (i.e. number of stress cycles before failure) of Class K cast iron conventional and modified railroad bearing adapters for onboard monitoring applications under different operational conditions based on experimentally validated Finite Element Analysis (FEA) stress results. Currently, freight railcars rely heavily on wayside hot-box detectors (HBDs) at strategic intervals to record bearing cup temperatures as the train passes at specified velocities. Hence, most temperature measurements are limited to certain physical railroad locations. This limitation gave way for an optimized sensor that could potentially deliver significant insight on continuous bearing temperature conditions. …

Mechanical Properties Of Intermetallic Compounds In Electrodeposited Multilayered Thin Film At Small Scale By Nanoindentation

Faculty of Engineering University of Malaya

Mechanical properties of intermetallic compounds (IMCs) which were formed in electrodeposited Cu/Sn and Cu/Ni/Sn multilayered thin film have been investigated. The layers of Cu, Sn and Ni were formed by electrodeposition technique using copper pyrophosphate, tin methanesulfonic and nickel Watts baths, respectively. After synthesis, samples were subjected to high temperature aging at 150 degrees C for 168 h. Two different types of intermetallics Cu3Sn and Cu6Sn5 were formed in Cu/Sn. After adding ultra-thin layer of Ni (70 nm) in between Cu and Sn layers, (Cu, Ni)(6)Sn-5 was formed after aging at similar condition to that of Cu/Sn. Tin whisker growth …

Evaluating The Optical Properties Of Tio2 Nanofluid For A Direct Absorption Solar Collector

Faculty of Engineering University of Malaya

Recent studies specify that designated nanofluids may increase the proficiency of direct absorption solar thermal collectors. To determine the efficiency of nanofluids in solar applications, their capability to change light energy to thermal energy must be identified (i.e., the absorption spectrum of the solar material). In view of that, this study compares model predictions to spectroscopic measurements of extinction coefficients over wavelengths that are important for solar energy (200- 1100nm). In the first decade of nanofluid research, most of the focus was on measuring and modeling the fundamental thermophysical properties of nanofluids (i.e., thermal conductivity, density, viscosity, and convection coefficients). …

The Tribological And Electrochemical Behavior Of Hvof-Sprayed Cr3c2-Nicr Ceramic Coating On Carbon Steel

Faculty of Engineering University of Malaya

High Velocity Oxygen Fuel (HVOF) is an excellent approach to prepare a good, wear-resistant lamella of Chromium Carbide-Nickel Chrome (Cr3C2-NiCr) on carbon steel for high temperature application. This research investigates the effect of a thin, deposited layer of Cr3C2-NiCr on carbon steel in terms of wear and corrosion properties. The microstructure of the HVOF-sprayed Cr3C2-NiCr coating was characterized at each step by scanning electron microscopy. Wear testing was performed with a pin-on-disk tester. Wear weight loss was examined by applying different loads over a 9048.96 m sliding distance. Experimental results show that the wear resistance of the coated sample reduced …

Electrowetting Of Room Temperature Ionic Liquids (Rtils) For Capillary Force Manipulation, Abhay Vasudev, Ashish Jagtiani, Li Du, Jun Hu, Yanan Gao, Jiang Zhe

Dr. Jiang Zhe

The feasibility of using room temperature ionic liquids (RTILs) as the electrowetting liquid for capillary force microgrippers was studied. The non-volatility and thermal stability of ionic liquids make them suitable for droplet based microgripping application in high temperature and vacuum environments. Electrowetting on co-planar electrodes was utilized to dynamically change the contact angle of a 1-butyl-3-methylimidazolium hexafluorophosphate (BmimPF6 ) liquid bridge to control the capillary lifting forces. The lifting force generated by the liquid bridge was experimentally characterized. The maximum capillary force was 146μN. The dynamic response of the BmimPF6 liquid bridge was also characterized.

Numerical Investigation Of Temperature Field During Sintering Of Bioceramic Nanoparticles By Pulse Lasers, Chang Ye, Gary Cheng

Dr. Chang Ye

Traditional numerical study of the temperature field of laser thermal processing is based on two assumptions: 1. heat source is a surface heat flux, and 2. uniform material properties. This method is not accurate when it comes to the laser sintering of nanoparticle integrated bioceramics coating with certain porosity. In this paper, Heat transfer (HT) model and electromagnetic (EM) model is coupled to investigate the temperature field of bioceramics nanoparticles. The heat source calculated from EM field is simultaneously input into the HT model to calculate the temperature field of the nanoparticle assembly. The interaction between the nanoparticles in the …

Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone

Faculty of Engineering University of Malaya

The aim of this research is to study the properties of natural porous hydroxyapatite developed from bovine bone through a sintering process. Bovine bone samples were prepared and sintered in an air atmosphere at different temperatures ranging from 600 degrees C to 1000 degrees C. The sintered bodies were characterized to determine the phases present, bulk density, Ca/P ratio and Vickers hardness. In addition, the microstructural evolution of the sintered porous bodies was also examined. The results revealed that the thermal stability of the HA matrix was not disrupted and that all of the sintered bodies exhibited phase pure HA. …

Sintering Behaviour Of Natural Porous Hydroxyapatite Derived From Bovine Bone

Faculty of Engineering University of Malaya

The aim of this research is to study the properties of natural porous hydroxyapatite developed from bovine bone through a sintering process. Bovine bone samples were prepared and sintered in an air atmosphere at different temperatures ranging from 600 degrees C to 1000 degrees C. The sintered bodies were characterized to determine the phases present, bulk density, Ca/P ratio and Vickers hardness. In addition, the microstructural evolution of the sintered porous bodies was also examined. The results revealed that the thermal stability of the HA matrix was not disrupted and that all of the sintered bodies exhibited phase pure HA. …

Analysis Of Transient Natural Convection Flow Past An Accelerated Infinite Vertical Plate, Innovative Research Publications Irp India, Kaprawi S.

Innovative Research Publications IRP India

This work describes a vertical hot plate moves with acceleration and with variation wall temperature. The temperatures of the plate decrease with the increase of velocity of the plate. The temperature and velocity are given by the governing equations. The dimensionless equations of the problem have been solved numerically by the finite difference method. The temperature and the velocity profiles against several parameters like Prandtl Number, Grashoft number and time are presented. The results show that the temperature and velocity profiles are significantly influenced by Prandtl and Grashoft number.

Review Of Improvements In Wire Electrode Properties For Longer Working Time And Utilization In Wire Edm Machining

Faculty of Engineering University of Malaya

Wire electrical discharge machining (WEDM) is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing hard materials. WEDM has experienced explosive growth and complexity of equipment as well as rising demand for the basic process tool (the wire electrode). Greater taper angles, thicker workpieces, automatic wire threading, and long periods of unattended operation make the selection of the ideal wire a much more critical basis for achieving successful operation. This paper focuses on the evolution of EDM wire electrode technologies from using copper to the widely employed brass wire electrodes and …

Prosthetic Thermal Management Device, Garrett Dowd

Williams Honors College, Honors Research Projects

High temperatures in lower-limb prosthetics can lead to poor user skin conditions and mechanical slippage between the user’s limb and the prosthetic. This report presents an air-cooling device for a lower-limb prosthesis. This device’s purpose is to maintain a constant skin-prosthesis interface temperature. A compact heat sink and small fan were used to transfer the bio-heat to the ambient surroundings. By changing the power of the fan, the thermal resistance of the whole system can be adjusted to match various thermal loads and environmental temperatures. Heat pads were used to mimic the heat generation of a residual limb, and cooling …