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2003

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Articles 1 - 30 of 294

Full-Text Articles in Mechanical Engineering

Migration Of An Intruder Particle In A Boundary Driven Shear Flow, Jian Liu Dec 2003

Migration Of An Intruder Particle In A Boundary Driven Shear Flow, Jian Liu

Dissertations

This study reports on three-dimensional, discrete element simulations of a single large spherical intruder in a Couette shear flow composed of uniform sized particles. The simulation results are useful in providing a numerical reproduction of the experiments for size segregation and mixing. This in turn has a major importance in many industries which are concerned with handling of particles and powders, such as pharmaceutical manufacturing, agriculture, chemical and mineral processing.

Discrete element simulations are carried out using the "soft sphere" model of Walton, et. al., which provides a method for obtaining the information at a macroscopic level from multi-body collisions ...


Effect Of Fullerene Containing Lubricants On Wear Resistance Of Machine Components In Boundary Lubrication, Andriy Titov Dec 2003

Effect Of Fullerene Containing Lubricants On Wear Resistance Of Machine Components In Boundary Lubrication, Andriy Titov

Dissertations

Fullerenes, a new form of carbon nanomaterials, possess unique physical and mechanical properties that make their use as additives to liquid lubricants potentially beneficial. The goal of this study was to investigate the effect of fullerene containing lubricants on wear resistance of steel-bronze couples operating under boundary lubrication conditions. A mathematical model of deformed asperity contact was built to calculate real contact area and real contact pressure. Computer controlled wear friction testing methodology and equipment were designed, developed and implemented for obtaining reliable and objective experimental data. In addition, optical and scanning electron microscopy and standard surface texture analysis were ...


Vibration-Induced Densification Of Granule Materials, Ninghua Zhang Dec 2003

Vibration-Induced Densification Of Granule Materials, Ninghua Zhang

Dissertations

Physical experiments as well as discrete element simulations of vibration are carried out. The use of different amplitudes and frequencies are applied in the experiments to facilitate the observation of densification trends with mono-disperse acrylic spheres and multi-disperse polyethylene pellets. For mono-disperse acrylic spheres, four densification trends are found at different vibration conditions, and attaining the "maximum density" is closely related to the combination of vibration frequency and amplitude, in agreement with experiments in the literature. For multi-disperse polyethylene pellets, there is a substantial increase in solids fraction due to the effects of particle shape and surface friction. Computer simulations ...


Dielectrophoretic Manipulation Of Biological And Non-Biological Analytes In A Microfluidic Channel, Dawn J. Bennett Dec 2003

Dielectrophoretic Manipulation Of Biological And Non-Biological Analytes In A Microfluidic Channel, Dawn J. Bennett

Dissertations

Micro-total-analytical systems (μTASs) for analyzing chemical/biological substances are now used across a wide variety of applications ranging from biological warfare agent detection to the healthcare industry. The first step in the operation of a μTAS consists of concentrating and separating the analytes of interest from the background matrix and positioning them into selected locations for subsequent analysis. The use of ac electric fields was demonstrated to have promising potential for a μTAS because the application of an ac field suppresses undesirable electrolytic effects in the liquid. The main purpose of this work is to study micro-scale phenomena in a ...


Magneto-Rheological Fluid Orthosis For Suppressing Tremor, Hyoung-Joo Yeo Dec 2003

Magneto-Rheological Fluid Orthosis For Suppressing Tremor, Hyoung-Joo Yeo

Theses

Tremor is a common movement disorder that occurs with specific neurological conditions. This condition may seriously impact daily living activities. The aim of the present study is to evaluate the possibility of the development of a wearable technology that is capable of exerting torques at a user's joints for suppressing tremor.

This thesis is based on the concept of "smart structures" which are made of Magneto-Rheological (MR) fluid that can dynamically alter its viscosity under magnetic field. The wearable tremor suppressing orthosis needs several conditions. It should be safe, light weight, simple and small in structure, and easily attachable ...


Characterization Of Aluminum Powder Ignition, Salil Mohan Dec 2003

Characterization Of Aluminum Powder Ignition, Salil Mohan

Theses

Heating rate effect and particle size effect on ignition temperature of Al powder were studied to collect data for development of a possible Al powder ignition model. Aluminum ignition is associated with a highly accelerated burn rate and high combustion enthalpy. A new ignition model, which can adequately interpret these conditions, is needed to develop better propulsion fuels, explosives and incendiaries that use Al as an additive. This experimental program was focused on preparing framework for characterization of ignition kinetics of Al powder by determining the ignition temperature for different, systematically varied, heating rates and particle size. The experimental setup ...


Combustion Of Aerosolized Spherical Aluminum Powders And Flakes In Air, Binu Zacharia Eapen Dec 2003

Combustion Of Aerosolized Spherical Aluminum Powders And Flakes In Air, Binu Zacharia Eapen

Theses

Combustion rates and completeness of aerosolized spherical aluminum powders and flakes are compared using constant volume explosion experiments. The comparison of particles and flake sizes was made based on their specific surface areas determined using the Brunauer-Emmett-Teller (BET) method and respective "BET diameters". It is observed that the rates of pressure rise and rates of flame propagation were higher for aluminum powders with BET diameters of about 2 to 5 μm compared to aluminum flakes for which the BET diameters were under 1 μm In agreement with the flame propagation rates, the overall completeness of combustion was also higher for ...


Evaluation Of The Flail Space Model Utilizing Event Data Recorder Technology, Douglas John Gabauer Dec 2003

Evaluation Of The Flail Space Model Utilizing Event Data Recorder Technology, Douglas John Gabauer

Theses and Dissertations

Developed in the early 1980's, the flail space model has become the standard method for estimating occupant risk in full-scale crash tests involving roadside safety features. The widespread availability of airbags and increased seat belt usage rates in today's vehicle fleet, however, raise serious questions regarding the validity of the model. Recent implementation of Event Data Recorder (EDR) technology in a number of late model vehicles presents a different perspective on the assessment of the validity of occupant risk based on the flail space model. EDRs are capable of electronically recording data such as vehicle speed, brake status ...


Selecting Appropriate Product Concepts For Manufacture In Developing Countries, Danielle Johnson Dec 2003

Selecting Appropriate Product Concepts For Manufacture In Developing Countries, Danielle Johnson

Theses and Dissertations

There is a noticeable lack of production of indigenously engineered and manufactured products in Less Developed Countries (LDC's). Few products developed in these LDC's could be viable in competitive markets or even sold as components and supplies to other manufacturers of competitive goods. Assumintg that these less developed countries do not innovate and manufacture because they cannot, the next logical question to ask is why can they not?

This thesis looks at the problems of manufacture and design in LDC's from the standpoint of Product Development. It begins by looking at development theories, namely top down and ...


Establishing A Quantitative Foundation For Exactly Constrained Design, Alisha M. Hammond Dec 2003

Establishing A Quantitative Foundation For Exactly Constrained Design, Alisha M. Hammond

Theses and Dissertations

Exactly constrained (EC) design is a robust design method which can be used for mechanical assemblies. It entails using the minimum number of constraints to eliminate all desired motion.

While found by some engineers in industry to have many benefits (including robust assembly, no binding or play, ease of assembly, and the ability to tolerate the wear of parts), EC designs remain somewhat unrecognized by academia. One reason for this minimal exposure may be the lack of a quantitative foundation for such designs. This thesis describes the history and current background for EC designs, and it also begins to develop ...


Dec 2003, Tractor Museum Dec 2003

Dec 2003, Tractor Museum

Museum Planning and Development Documents

Introductions Curator's Report Treasurer's Report


Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study Dec 2003

Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study

A.S. Md Abdul Haseeb

Three aluminium metal matrix composites containing reinforcing particles of B4C, SiC and Al2O3 (0-20vol.%) were processed. The stir-casting manufacturing route followed by hot extrusion was utilized, being one of the cost-effective industrial methods. A clear interfacial reaction product/layer was found at Al-SiC interface for composites held for a relatively long processing time (>30 min). No reaction product was observed at Al-B4C and Al-Al2O3 interfaces at the resolution limit of the SEM used. On the other hand, two secondary phases (alumina and another phase containing aluminium, boron and carbon) were found in the aluminum matrix away from the interface in ...


Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study Dec 2003

Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study

A.S. Md Abdul Haseeb

Three aluminium metal matrix composites containing reinforcing particles of B4C, SiC and Al2O3 (0-20vol.%) were processed. The stir-casting manufacturing route followed by hot extrusion was utilized, being one of the cost-effective industrial methods. A clear interfacial reaction product/layer was found at Al-SiC interface for composites held for a relatively long processing time (>30 min). No reaction product was observed at Al-B4C and Al-Al2O3 interfaces at the resolution limit of the SEM used. On the other hand, two secondary phases (alumina and another phase containing aluminium, boron and carbon) were found in the aluminum matrix away from the interface in ...


Processes For Nanomachining Using Carbon Nanotubes, Robert Ryan Vallance, Apparao M. Rao, M. Pinar Mengüç Dec 2003

Processes For Nanomachining Using Carbon Nanotubes, Robert Ryan Vallance, Apparao M. Rao, M. Pinar Mengüç

Mechanical Engineering Faculty Patents

Novel methods and devices for nanomachining a desired pattern on a surface of a conductive workpiece are disclosed. In one aspect, the method comprises using an electron beam emitted from one or more nanotubes to evaporate nanoscale quantities of material from the workpiece surface. The surface of the workpiece to be machined may be excited to a threshold energy to reduce the amount of power required to be emitted by the nanotube. In another aspect, a device is described for nanomachining a desired pattern on a surface of a conductive workpiece, comprising a vessel capable of sustaining a vacuum, a ...


Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study, Haseeb Asma Dec 2003

Microstructure And Interface Characteristics Of B4c, Sic And Al2o3 Reinforced Al Matrix Composites: A Comparative Study, Haseeb Asma

Haseeb ASMA

Three aluminium metal matrix composites containing reinforcing particles of B4C, SiC and Al2O3 (0-20 vol.%) were processed. The stir-casting manufacturing route followed by hot extrusion was utilized, being one of the cost-effective industrial methods. A clear interfacial reaction product/layer was found at Al-SiC interface for composites held for a relatively long processing time (>30 min). No reaction product was observed at Al-B4C and Al-Al2O3 interfaces at the resolution limit of the SEM used. On the other hand, two secondary phases (alumina and another phase containing aluminium, boron and carbon) were found in the aluminum matrix away from the interface ...


Chemical Kinetics And Thermal Hydraulics Of Lead Bismuth Flow Loops, Kanthi Kiran Dasika Dec 2003

Chemical Kinetics And Thermal Hydraulics Of Lead Bismuth Flow Loops, Kanthi Kiran Dasika

UNLV Theses, Dissertations, Professional Papers, and Capstones

The objective of the thesis is to study the effect of chemical kinetics and thermal hydraulics of Lead Bismuth Eutectic (LBE) flow in the Materials Test Loop (MTL). The Materials Test Loop, also known as the Delta Loop, was built in Los Alamos National Laboratories (LANL) to obtain the experimental data for corrosion estimation and analysis. It is a well-known fact that corrosion plays an important role in the design of nuclear thermal hydraulic systems. Since the MTL is a multi-section closed system that differs in diameter from one part to another, an intensive study on the overall and regional ...


Design And Development Of A Lubrication Pump For A Horizontally Mounted Air-Conditioning Compressor., Kenneth T. Gilbert Dec 2003

Design And Development Of A Lubrication Pump For A Horizontally Mounted Air-Conditioning Compressor., Kenneth T. Gilbert

Electronic Theses and Dissertations

Horizontally mounted compressors offer the advantage of reduced height in central air-conditioning units but prove difficult to produce economically due to costs associated with the manufacture of acceptable lubrication systems for the compressors. This study develops an effective, affordable oil pump for use on a horizontal compressor. Concepts are proven through testing of prototype assemblies. Test results drive modifications for future prototypes, and prototypes demonstrating adequate performance are modified for ease of manufacture.

Research in this study proves that the most suitable design results from a modification of a rotating vane pump. The pump’s modifications enable it to pump ...


Analysis And Design Of A Gear Shifting Mechanism For Transmission Based Actuators, Kalyana Bhargava Ganti Dec 2003

Analysis And Design Of A Gear Shifting Mechanism For Transmission Based Actuators, Kalyana Bhargava Ganti

Masters Theses

The fundamental idea of Transmission Based Actuators (TBA) is to incorporate a multi-speed transmission to spread a servomotor’s torque speed characteristics across a wider output speed range. TBA uses multi-speed transmissions such that heavy, high-torque motors can be traded for high-speed, reduced mass motor-transmission combinations. TBA design consists of a D.C. Brushless motor, discrete gear transmission and a fixed reduction. Of these, the fundamental to the proof of principle of TBA is the design of the discrete gear transmission.

Basically the DVT is a three-speed gearbox consisting of 3 sets of epicyclic gears. Every planetary gear set is ...


Why Toyota And Honda Topped The 2002 J.D. Power Quality Study, Susan Lightle, Kenneth Yale Rosenzweig, John Talbott Dec 2003

Why Toyota And Honda Topped The 2002 J.D. Power Quality Study, Susan Lightle, Kenneth Yale Rosenzweig, John Talbott

Accounting Faculty Publications

Toyota again topped the annual J. D. Power and Associates quality study released in late May of 2002. Toyota scored the highest mark ever with l 07 defects per l 00 vehicles, while Honda came in second with 113 defects. The study was based on responses of approximately 65,000 new car owners queried during their first 90-days of ownership.

These results do not surprise us, as we have been fortunate to make numerous sojourns to the Toyota plant in Georgetown, Kentucky, and observe the manufacturing processes. These trips were normally facilitated by a former Japanese student of ours, Minako ...


Investigation Of Compound Micro Cantilever For Imaging And Identifying Micro/Nano Particulates, Ramanathan Narayanan Dec 2003

Investigation Of Compound Micro Cantilever For Imaging And Identifying Micro/Nano Particulates, Ramanathan Narayanan

Masters Theses

Atomic Force Microscopes (AFM) are typically used to image surfaces along with small particulates that may be deposited on the surface. Surface imaging can be made down to the atomic level but usually it is conducted at the nano and micro scales. It is highly desirable to identify the constituency of particulates on the surface and if possible determine the chemical and physical identity of particulates. The objective of the research presented in this thesis is to establish the feasibility of using dual micro cantilevers to determine the physical constituency of nano particles deposited to the micro surface. The goal ...


Parameter Study On Topology Optimization Of Constrained Layer Damping Treatments, Rohan Vinay Pai Dec 2003

Parameter Study On Topology Optimization Of Constrained Layer Damping Treatments, Rohan Vinay Pai

Masters Theses

This study investigates the optimal topology of a constrained layer damping treatment involving viscoelastic materials under a static load for different boundary conditions in order to maximize the damping loss factor for the first vibrating mode of the base structure. Different parameter studies are carried out for the two boundary conditions and conclusions are drawn based on the loss factor results and the novel topologies that emerge from these optimization results. The novel topologies are then used to interpret shapes that are more reasonable to manufacture. Tremendous improvement in the loss factor (up to 1250%) is obtained by topology optimization ...


Modeling Of Corrugated Graphite Foam Heat Exchangers, Timothy Henry Norton Jr. Dec 2003

Modeling Of Corrugated Graphite Foam Heat Exchangers, Timothy Henry Norton Jr.

Masters Theses

A new manufacturing process was recently developed by the Oak Ridge National Laboratory for the production of graphite foam. The high thermal conductivity and heat transfer area of the foam make it desirable for thermal management applications such as compact heat exchangers. The heat transfer capabilities of the foam are especially useful in internal forced convection applications. However, due to the very low permeability of graphite foam, pressure-drop is very high compared to other porous media, and pressuredrop reduction schemes are necessary to ensure its practical application. Pressure-drop reduction can be achieved through the strategic machining of graphite foam into ...


Development And Validation Of A 3-D Model To Predict Knee Joint Loading During Dynamic Movement, Scott G. Mclean, Anne Su, Antonie J. Van Den Bogert Dec 2003

Development And Validation Of A 3-D Model To Predict Knee Joint Loading During Dynamic Movement, Scott G. Mclean, Anne Su, Antonie J. Van Den Bogert

Mechanical Engineering Faculty Publications

The purpose of this study was to develop a subject-specific 3-D model of the lower
extremity to predict neuromuscular control effects on 3-D knee joint loading during movements that can potentially cause injury to the anterior cruciate ligament (ACL) in the knee. The simulation consisted of a forward dynamic 3-D musculoskeletal model of the lower extremity, scaled to represent a specific subject. Inputs of the model were the initial position and velocity of the skeletal elements, and the muscle stimulation patterns. Outputs of the model were movement and ground reaction forces, as well as resultant 3-D forces and moments acting ...


Simulated Properties Of Kagomé And Tetragonal Truss Core Panels, S. Hyun, Anette M. Karlsson, S. Torquato, A. G. Evans Dec 2003

Simulated Properties Of Kagomé And Tetragonal Truss Core Panels, S. Hyun, Anette M. Karlsson, S. Torquato, A. G. Evans

Mechanical Engineering Faculty Publications

The finite element method has been used to simulate the properties of panels with Kagomé and tetragonal cores under compressive and shear loading. The simulation has been performed for two different materials: a Cu-alloy with extensive strain hardening and an Al-alloy with minimal hardening. It is shown that the Kagomé core is more resistant to plastic buckling than the tetragonal core under both compression and shear. One consequence is that the Kagomé structure has the greater load capacity and a deferred susceptibility to softening. Another is that the Kagomé core is isotropic in shear: contrasting with the soft orientations exhibited ...


Multiple Uav Cooperative Search Under Collision Avoidance And Limited Range Communication Constraints, Randal W. Beard, Timothy W. Mclain Dec 2003

Multiple Uav Cooperative Search Under Collision Avoidance And Limited Range Communication Constraints, Randal W. Beard, Timothy W. Mclain

Faculty Publications

This paper focuses on the problem of cooperatively searching, using a team of unmanned air vehicles (UAVs), an area of interest that contains regions of opportunity and regions of potential hazard. The objective of the UAV team is to visit as many opportunities as possible, while avoiding as many hazards as possible. To enable cooperation, the UAVs are constrained to stay within communication range of one another. Collision avoidance is also required. Algorithms for team-optimal and individually-optimal/team-suboptimal solutions are developed and their computational complexity compared. Simulation results demonstrating the feasibility of the cooperative search algorithms are presented.


Dynamic Modeling Of Compliant Constant-Force Compression Mechanisms, Cameron Boyle, Larry L. Howell, Spencer P. Magleby, Mark S. Evans Dec 2003

Dynamic Modeling Of Compliant Constant-Force Compression Mechanisms, Cameron Boyle, Larry L. Howell, Spencer P. Magleby, Mark S. Evans

Faculty Publications

A mathematical dynamic model is derived for compliant, constant-force compression-mechanisms, based on the pseudo-rigid-body model simplification of the device. The compliant constant-force compression mechanism (CFCM) is a slider mechanism incorporating large-deflection beams, which outputs near-constant-force across the range of its designed deflection. The equation of motion is successfully calibrated with empirical data from five separate mechanisms, comprising two basic configurations of CFCMs. The dynamic equation is derived from a generalized pseudo-rigid-body model. This allows every configuration to be represented by the same model, so a separate treatment is not required for each configuration. An unexpected dynamic trait of the constant-force ...


Memories Of Dad 15.11.1902- 16.10.1970 A Celebration Of The Life And Works Of Edmund Ramsay Wigan, Marcus R. Wigan Nov 2003

Memories Of Dad 15.11.1902- 16.10.1970 A Celebration Of The Life And Works Of Edmund Ramsay Wigan, Marcus R. Wigan

Marcus R Wigan

Edmund Ramsay Wigan was a distinguished Acoustical and Mechanical Engineer, who patented literally several dozen devices and ideas, was responsible for the field radios used by the Allied forces in Europe in World War 2, and when invited as the special merit Senior Principal at the BBC Research lab in Kingston, Surrey, invented the quality meters, tuned all the BBC broadcasting aerials for quality, and did applied research creating a reliable measure for subjective levels of sound distortion. As a minor practical measure invented the one cycle offset used ever since to avoid feedback in large multi-miked rooms. He was ...


Evaluation Of Event Data Recorders In Real World Crashes And Full-Scale Crash Tests, Lewis Thomas Clayton Jr. Nov 2003

Evaluation Of Event Data Recorders In Real World Crashes And Full-Scale Crash Tests, Lewis Thomas Clayton Jr.

Theses and Dissertations

With the advent of advanced safety systems in U.S. passenger vehicles, there has been increased interest shown by automakers in recording crash related parameters that ultimately lead to the deployment of these safety systems in what are known as Event Data Recorders (EDRs). Since the only other record of these parameters, specifically crash pulse, comes from staged crash tests in a controlled environment, the advent of the EDR has become increasingly important to crash researchers. The purpose of this study is to quantify the performance of EDRs in full-scale crash tests and real world crashes.

Comparison of EDRs with ...


The Distribution Of Internal Interfaces In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Paul Wynblatt Nov 2003

The Distribution Of Internal Interfaces In Polycrystals, Brent L. Adams, Bassem S. El-Dasher, Gregory S. Rohrer, Anthony D. Rollett, David M. Saylor, Paul Wynblatt

Faculty Publications

This work was supported by the MRSEC program of the National Science Foundation under Award Number DMR-0079996. Recent advances both in experimental instrumentation and computing power have made it possible to interrogate the distribution of internal interfaces in polycrystals and the three dimensional structure of the grain boundary network with an unprecedented level of detail. The purpose of this paper is to review techniques that can be used to study the mesoscopic crystallographic structure of grain boundary networks and to summarize current findings. Recent studies have shown that grain surfaces within dense polycrystals favor the same low energy planes that ...


Modeling The Transient Response Of A Thermosyphon, James Kirk Storey Nov 2003

Modeling The Transient Response Of A Thermosyphon, James Kirk Storey

Theses and Dissertations

Thermosyphon transient operation was numerically modeled. The numerical model presented in this work overcame the limitations of previous studies by including transient conduction in the vessel wall, shear stress between the rising vapor and the falling film in the thermosyphon, the influence of the mass in the liquid pool in the evaporator, and by using a more refined and accurate numerical grid. Unique to this model was the accounting for temporal changes in the effective length of the vapor space due to the expanding and contracting of non-condensable gases in the vapor space. The model assumed quasi-steady one-dimensional vapor flow ...