Engineering Commons^™

My Lecture Notes (Heat Transfer 1) - (Chapter8), Dr Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.

The Design And Validation Of A Computational Rigid Body Model For Study Of The Radial Head, Cassandra Woodcock

Theses and Dissertations

Rigid body modeling has historically been used to study various features of the elbow joint including both physical and computational models. Computational modeling provides an inexpensive, easily customizable, and effective method by which to predict and investigate the response of a physiological system to in vivo stresses and applied perturbations. Utilizing computer topography scans of a cadaveric elbow, a virtual representation of the joint was created using the commercially available MIMICS(TM) and SolidWorks(TM) software packages. Accurate 3D articular surfaces, ligamentous constraints, and joint contact parameters dictated motion. The model was validated against two cadaveric studies performed by Chanlalit et al. …

Localization Of Auditory Spatial Targets In Sighted And Blind Subjects, Richard Nuckols

Theses and Dissertations

This research was designed to investigate the fundamental nature in which blind people utilize audible cues to attend to their surroundings. Knowledge on how blind people respond to external spatial stimuli is expected to assist in development of better tools for helping people with visual disabilities navigate their environment. There was also interest in determining how blind people compare to sighted people in auditory localization tasks. The ability of sighted individuals, blindfolded individuals, and blind individuals in localizing spatial auditory targets was assessed. An acoustic display board allowed the researcher to provide multiple sound presentations to the subjects. The subjects’ …

Vapor–Liquid–Solid Growth Of Serrated Gan Nanowires: Shape Selection Driven By Kinetic Frustration, Zheng Ma, Dillon Mcdowell, Eugen Panaitescu, Albert V. Davydov, Moneesh Upmanyu, Latika Menon

Moneesh Upmanyu

Compound semiconducting nanowires are promising building blocks for several nanoelectronic devices yet the inability to reliably control their growth morphology is a major challenge. Here, we report the Au-catalyzed vapor–liquid–solid (VLS) growth of GaN nanowires with controlled growth direction, surface polarity and surface roughness. We develop a theoretical model that relates the growth form to the kinetic frustration induced by variations in the V(N)/III(Ga) ratio across the growing nanowire front. The model predictions are validated by the trends in the as-grown morphologies induced by systematic variations in the catalyst particle size and processing conditions. The principles of shape selection highlighted …

A Study Of Titania Nanotube Synthesis In Chloride-Ion-Containing Media, E. Panaitescu, C. Richter, L. Menon

Eugen Panaitescu

We have completed a detailed experimental investigation into the recently discovered synthesis of titania nanotubes in chloride-ion-containing media. We show that the role of the chloride ions is catalytic and it has a strong effect in increasing the reactivity of the solution, while the nature of cations has no visible role. We have identified the critical parameters for optimal growth and fast production of nanotubes, and a basic growth mechanism for the tubes is proposed. This opens routes for significant improvements of the method toward uniformity and/or better overall yield, making it a viable alternative to the present established methods.

Toward Tailored Functionality Of Titania Nanotube Arrays: Interpretation Of The Magnetic-Structural Correlations, Pegah M. Hosseinpour, Eugen Panaitescu, Don Heiman, Latika Menon, Laura H. Lewis

Eugen Panaitescu

Ordered arrays of titania nanotubes (NTs) are considered as good candidates for photocatalytic applications including water splitting. Considering that the functionality of these nanostructures is influenced by their morphology, electronic and the crystallographic structure, fundamental understanding of these properties and their possible correlations can clarify the approaches toward enhanced photocatalytic efficiency. In this work, ordered arrays of titania NTs are synthesized electrochemically and are subjected to isochronal annealing treatments in various atmospheres (oxygen-rich, oxygen-deficient and reducing) to modify their morphology, crystal and electronic structure. Upon characterization of these NTs, direct correlations are found between the annealing atmosphere and the corresponding …

Vapor–Liquid–Solid Growth Of Serrated Gan Nanowires: Shape Selection Driven By Kinetic Frustration, Zheng Ma, Dillon Mcdowell, Eugen Panaitescu, Albert V. Davydov, Moneesh Upmanyu, Latika Menon

Eugen Panaitescu

Compound semiconducting nanowires are promising building blocks for several nanoelectronic devices yet the inability to reliably control their growth morphology is a major challenge. Here, we report the Au-catalyzed vapor–liquid–solid (VLS) growth of GaN nanowires with controlled growth direction, surface polarity and surface roughness. We develop a theoretical model that relates the growth form to the kinetic frustration induced by variations in the V(N)/III(Ga) ratio across the growing nanowire front. The model predictions are validated by the trends in the as-grown morphologies induced by systematic variations in the catalyst particle size and processing conditions. The principles of shape selection highlighted …

Toward Tailored Functionality Of Titania Nanotube Arrays: Interpretation Of The Magnetic-Structural Correlations, Pegah M. Hosseinpour, Eugen Panaitescu, Don Heiman, Latika Menon, Laura H. Lewis

Donald Heiman

Ordered arrays of titania nanotubes (NTs) are considered as good candidates for photocatalytic applications including water splitting. Considering that the functionality of these nanostructures is influenced by their morphology, electronic and the crystallographic structure, fundamental understanding of these properties and their possible correlations can clarify the approaches toward enhanced photocatalytic efficiency. In this work, ordered arrays of titania NTs are synthesized electrochemically and are subjected to isochronal annealing treatments in various atmospheres (oxygen-rich, oxygen-deficient and reducing) to modify their morphology, crystal and electronic structure. Upon characterization of these NTs, direct correlations are found between the annealing atmosphere and the corresponding …

Toward Tailored Functionality Of Titania Nanotube Arrays: Interpretation Of The Magnetic-Structural Correlations, Pegah M. Hosseinpour, Eugen Panaitescu, Don Heiman, Latika Menon, Laura H. Lewis

Laura H. Lewis

Ordered arrays of titania nanotubes (NTs) are considered as good candidates for photocatalytic applications including water splitting. Considering that the functionality of these nanostructures is influenced by their morphology, electronic and the crystallographic structure, fundamental understanding of these properties and their possible correlations can clarify the approaches toward enhanced photocatalytic efficiency. In this work, ordered arrays of titania NTs are synthesized electrochemically and are subjected to isochronal annealing treatments in various atmospheres (oxygen-rich, oxygen-deficient and reducing) to modify their morphology, crystal and electronic structure. Upon characterization of these NTs, direct correlations are found between the annealing atmosphere and the corresponding …

Toward Tailored Functionality Of Titania Nanotube Arrays: Interpretation Of The Magnetic-Structural Correlations, Pegah M. Hosseinpour, Eugen Panaitescu, Don Heiman, Latika Menon, Laura H. Lewis

Latika Menon

Ordered arrays of titania nanotubes (NTs) are considered as good candidates for photocatalytic applications including water splitting. Considering that the functionality of these nanostructures is influenced by their morphology, electronic and the crystallographic structure, fundamental understanding of these properties and their possible correlations can clarify the approaches toward enhanced photocatalytic efficiency. In this work, ordered arrays of titania NTs are synthesized electrochemically and are subjected to isochronal annealing treatments in various atmospheres (oxygen-rich, oxygen-deficient and reducing) to modify their morphology, crystal and electronic structure. Upon characterization of these NTs, direct correlations are found between the annealing atmosphere and the corresponding …

Vapor–Liquid–Solid Growth Of Serrated Gan Nanowires: Shape Selection Driven By Kinetic Frustration, Zheng Ma, Dillon Mcdowell, Eugen Panaitescu, Albert V. Davydov, Moneesh Upmanyu, Latika Menon

Latika Menon

Compound semiconducting nanowires are promising building blocks for several nanoelectronic devices yet the inability to reliably control their growth morphology is a major challenge. Here, we report the Au-catalyzed vapor–liquid–solid (VLS) growth of GaN nanowires with controlled growth direction, surface polarity and surface roughness. We develop a theoretical model that relates the growth form to the kinetic frustration induced by variations in the V(N)/III(Ga) ratio across the growing nanowire front. The model predictions are validated by the trends in the as-grown morphologies induced by systematic variations in the catalyst particle size and processing conditions. The principles of shape selection highlighted …

New Three-Phase Multilevel Inverter With Reduced Number Of Power Electronic Components, Saad Mekhilef

Saad Mekhilef

In this paper, a new configuration of a three-phase five-level multilevel voltage-source inverter is introduced. The proposed topology constitutes the conventional three-phase two-level bridge with three bidirectional switches. A multilevel dc link using fixed dc voltage supply and cascaded half-bridge is connected in such a way that the proposed inverter outputs the required output voltage levels. The fundamental frequency staircase modulation technique is easily used to generate the appropriate switching gate signals. For the purpose of increasing the number of voltage levels with fewer number of power electronic components, the structure of the proposed inverter is extended and different methods …

My Lecture Notes (Heat Transfer 1) - (Chapter 7), Dr Alireza Zolfaghari

Dr Alireza Zolfaghari

No abstract provided.

Method For Ultrasound Vibrometry Using Orthogonal Basis Functions, Yi Zheng, Aiping Yao, James Fowler Greenleaf, Shigao Chen, Matthew W. Urban

Electrical and Computer Engineering Faculty Patents

A method for measuring a mechanical property of a subject includes using an ultrasound transducer to apply ultrasonic vibration pulses to a location in a subject in order to induce shear waves at multiple prescribed orthogonal frequencies in the subject. The ultrasound transducer is directed by an excitation signal that is composed of multiple orthogonal basis functions, each having a given frequency component corresponding to the prescribed orthogonal frequencies. The power level of each orthogonal basis function is independently adjustable. The excitation signal can be sparsely sampled, or portions of the excitation signal can be removed in order to improve …

Intercalibration Of Quikscat And Oscat Land Backscatter, John Colin Barrus

Theses and Dissertations

The Ku-band SeaWinds-on-QuikSCAT scatterometer (QuikSCAT) operated continuously from 1999 to 2009. Though its primary mission was to estimate global ocean winds, QuikSCAT has proven useful in a variety of geophysical studies using land backscatter measurements. The end of the primary QuikSCAT mission in 2009 has prompted interest for continuing the QuikSCAT land dataset with other scatterometers. The Oceansat-2 scatterometer (OSCAT), launched in 2009, is a viable candidate for continuing the QuikSCAT time series because of the similarities of both sensors in function and design. An important difference in the sensors is that they operate at slightly different incidence angles. Continuing …

Examination Of The Effect Of Different Training Metrics On Performance Of A Minimally Invasive Surgery Transfer Task, Cristofer Madera

Theses and Dissertations

The purpose of this experiment was to determine if there existed techniques to more efficiently train prospective surgeons the skills necessary to capably perform minimally invasive surgical procedures. Also, we wanted to know if trainees could be pushed to cognitively define a laparoscopic environment with a novel hand-eye relationship. To explore these questions, a simulation was setup wherein subjects would perform a laparoscopic transfer task and receive active feedback during training. Different subjects would receive different metrics as feedback and a comparison would be made between subjects with respect to standard metrics. Results of this experiment show that all subjects …

Application Of Support Vector Machine In Predicting The Market's Monthly Trend Direction, Ali Alali

Dissertations and Theses

In this work, we investigate different techniques to predict the monthly trend direction of the S&P 500 market index. The techniques use a machine learning classifier with technical and macroeconomic indicators as input features. The Support Vector Machine (SVM) classifier was explored in-depth in order to optimize the performance using four different kernels; Linear, Radial Basis Function (RBF), Polynomial, and Quadratic. A result found was the performance of the classifier can be optimized by reducing the number of macroeconomic features needed by 30% using Sequential Feature Selection. Further performance enhancement was achieved by optimizing the RBF kernel and SVM parameters …

Specimen Size Effect On Shear Behavior Of Loose Sand In Triaxial Testing, Tarek Omar

Electronic Thesis and Dissertation Repository

Triaxial tests are widely used to determine the behavior and strength characteristics of soils without due attention to the differences in specimen size. Several drained and undrained monotonic triaxial compression shear tests are performed on three different specimen sizes of the same sand to investigate the influence of specimen size and scale effect on the shear behavior. The test results indicate that the behavior of loose sand is strongly influenced by the specimen size, with larger specimens exhibiting a stiffer behavior during isotropic compression, and mobilizing smaller shear strengths and effective friction angles. Triaxial testing also involves many sources of …

Hydrodynamics In Recirculating Fluidized Bed Mimicking The Stripper Section Of The Fluid Coker, Francisco J. Sanchez Careaga

Electronic Thesis and Dissertation Repository

The stripper section of a Fluid Coker^TM consists of a system of baffles (sheds) that enhances the removal of interstitial and adsorbed hydrocarbon vapors from the fluidized coke-particles. Most of the hydrocarbon-vapors released below a stripper shed flow up to the stripper shed, where they may crack and form coke deposits that foul the shed. Extensive fouling changes the shapes of the sheds, makes them thicker and reduces the free-space between the adjacent sheds until downward solids flow is so impaired that the Coker has to be shut down.

The Radioactive Particle Tracking (RPT) technique allows the determination of …

Experimental Modeling Of Wind Farm Topography And Canopy, Dan S. Parvu

Electronic Thesis and Dissertation Repository

As an important renewable energy source for electricity generation, wind energy must rely on efficient and accurate wind resource assessment for the siting and the design of wind farms. Traditionally relying on numerical modeling, current wind farms built in Canada, notably, experience an under-performance in terms of power generation. This work studies an alternative approach to wind farm modeling through experimental wind tunnel testing.

The objective of the work is to develop methodologies on how topographic and forest canopy models should be built as scale models of full scale wind farms. The models developed are validated by comparing the data …

Giant Interlayer Magnetoresistances And Strong Anisotropy In P-Type Sb2te3 Single Crystals, Zengji Yue, Xiaolin Wang, S Dou

Zengji Yue

Anisotropic interlayer magneto-transport properties have been studied over a broad range of temperatures and magnetic fields in p-type Sb2Te3 single crystals. Giant interlayer magnetoresistance (MR) of up to 400% was observed, which exhibits quadratic field dependences in low fields and becomes linear at high fields without any trend towards saturation. The interlayer MR displays strong anisotropy and is attributable to the anisotropy of the Fermi surface. The observed giant anisotropic interlayer MR could find applications in p-type Sb2Te3 based magneto-electronic devices.

Observation Of Field-Induced Polarization Of Valleys In P-Type Sb 2te 3 Single Crystals, Z J. Yue, C B. Zhu, S X. Dou, Xiaolin Wang

Zengji Yue

A flow of carriers along the c axis is extremely sensitive to the orientation of an in-plane magnetic field due to in-plane mass anisotropy in layered compounds. Based on this mechanism, a rotatable in-plane magnetic field has been applied as a valley valve to tune the contribution of each valley in p-type Sb₂Te₃ bulk single crystals to the total conductivity and interlayer magnetoresistance (MR). A valley-polarized current is generated, and the angular-dependent interlayer MR of up to 160% represents strong anisotropy. There are six inequivalent peaks over all temperature and magnetic field ranges. The giant MR results …

Giant And Anisotropic Magnetoresistances In P-Type Bi-Doped Sb 2te 3 Bulk Single Crystals, Z J. Yue, Xiaolin Wang, Y Du, S M. Mahboobeh, Frank F. Yun, Z X. Cheng, S. X. Dou

Zengji Yue

Antimony telluride (Sb2Te3) compounds are well known as excellent thermoelectric materials and have been recently confirmed as three-dimensional topological insulators. In this letter, we have investigated the anisotropic magneto-transport properties of p-type Bi-doped Sb2Te3 bulk single crystals over a broad range of temperatures, degrees and magnetic fields. Giant magnetoresistance (MR) of up to 230% was observed, which exhibits quadratic field dependences in low fields and becomes linear at high fields without any trend towards saturation. The giant MR also shows strong anisotropy with anisotropy ratio up to 210% in angle-dependent measurements. The giant MR might result from strong intervalley and …

Large Networks Of Vertical Multi-Layer Graphenes With Morphology-Tunable Magnetoresistance, Zengji Yue, Igor Levchenko, Shailesh Kumar, Donghan Seo, Xiaolin Wang, S X. Dou, Kostya Ken Ostrikov

Zengji Yue

We report on the comparative study of magnetotransport properties of large-area vertical few-layer graphene networks with different morphologies, measured in a strong (up to 10 T) magnetic field over a wide temperature range. The petal-like and tree-like graphene networks grown by a plasma enhanced CVD process on a thin (500 nm) silicon oxide layer supported by a silicon wafer demonstrate a significant difference in the resistance-magnetic field dependencies at temperatures ranging from 2 to 200 K. This behaviour is explained in terms of the effect of electron scattering at ultra-long reactive edges and ultra-dense boundaries of the graphene nanowalls. Our …

Limit For Thermal Transport Reduction In Si Nanowires With Nanoengineered Corrugations, Sean E. Sullivan, Keng-Hua Lin, Stanislav Avdoshenko, Alejandro Strachan

Birck and NCN Publications

Non-equilibrium molecular dynamics simulations reveal that the thermal conductance of Si nanowires with periodic corrugations is lower than that of smooth wires with cross-sections equivalent to the constricted portions. This reduction in conductance is up to 30% and tends to plateau with increasing corrugation height. Spatially resolved temperature and heat current maps provide a microscopic understanding of this effect; we find that 80% of the heat current is carried through the constricted area even for high-amplitude corrugations. More importantly, we show that temperature gradient inversion and heat current vortices at the ridge peaks establish fundamental limits on maximum conductance reduction. …

Polarization Diversity In The Presence Of Multipath Propagation, Grant Taylor Wagner

Theses and Dissertations

The possibility of polarization diversity using left and right hand circular polarization (LHCP and RHCP) in the presence of multipath propagation is examined. We show that there are differences in the received signal for LHCP and RHCP for a number of realistic scenarios. Because multipath propagation can produce different LHCP and RCHP signals, there exists the possibility for diversity improvement involving the two polarizations.

Structural Analysis And Optimization Of Skyscrapers Connected With Skybridges And Atria, Amy Jean Taylor Mccall

Theses and Dissertations

Skybridges and atria between buildings are becoming more and more popular. Most current skybridge connections are either roller or rigid-connections. This dissertation presents an investigation of the structural analysis and optimization of skyscraper systems with hinge-connected skybridges, and compares the results to skyscraper systems with roller-connected skybridges and to skyscraper systems without skybridges altogether. Also presented is an investigation of the structural analysis and optimization of skyscrapers both with and without atria between the buildings. It was assumed that the atria envelope was constructed with cushions made from lightweight, transparent, and flexible Ethylene Tetrafluoroethylene (ETFE). A simplified skyscraper skybridge model …

Investigation Of Hollow Bar Micropiles In Cohesive Soil, Osama F. El Hadi Drbe

Electronic Thesis and Dissertation Repository

Micropiles are used in various applications, including low capacity micropile networks, underpinning and seismic retrofitting of existing foundations and high capacity foundations for new structures. They facilitate fast installation with a high degree of ground improvement. The current Federal Highway Administration (FHWA) design guidelines designate hollow bar micropiles as Type B micropiles, even though their construction technique is different than typical Type B, which results in overly conservative design. In addition, the current practice for construction of hollow bar micropiles is limited to drilling bit/hollow bar diameter ratio of 2.5 or less. In this thesis, full-scale load tests were conducted …

Igert: Sensor Science, Engineering, And Informatics, Mary-Kate Beard-Tisdale, Robert J. Lad, Rosemary L. Smith, John F. Vetelino, Michael Warboys

University of Maine Office of Research Administration: Grant Reports

This Sensor Science, Engineering and Informatics (SSEI) IGERT program will provide multidisciplinary doctoral training in the area of sensor systems ranging from the science and engineering of new materials and sensing mechanisms to the interpretation of sensor data. The design and management of effective sensor systems requires a holistic understanding of how information is collected, stored, integrated, evaluated, and communicated within sensing systems and to decision makers in diverse application contexts. The SSEI IGERT weaves together three research focus areas: (1) Sensor Materials and Devices, (2) Sensor Systems and Networks, and (3) Sensor Informatics. The intellectual merit of the project …

The Probabilistic Characterization Of Severe Rainstorm Events: Applications Of Threshold Analysis To Climate Change Impacts, Barry A. Palynchuk Phd

Barry A. Palynchuk PhD

A summary of PhD thesis, with emphasis upon storm event definition, and climate change impacts upon rainfall depth, duration, and intensity.