Engineering Commons^™

Fault-Tolerant Technique For Δ-Connected Ac-Motor Drives, Ahmed Mohamed Sayed Ahmed, Behrooz Mirafzal, Nabeel Demerdash

Electrical and Computer Engineering Faculty Research and Publications

A fault-tolerant technique for motor-drive systems is introduced in this paper. The technique is merely presented for ac motors with Δ-connected circuits in their stator windings. In this technique, the faulty phase is isolated by solid-state switches after the occurrence of a failure in one of the stator phases. Then, the fault-tolerant technique manages current-flow in the remaining healthy phases. This technique is to significantly mitigate torque pulsations, which are caused by an open-Δ configuration in the stator windings. The performance of the fault-tolerant technique was experimentally verified using a 5-hp 460-V induction motor-drive system and the results are presented …

Printed Circularly-Polarized Antenna With Ultra-Wide Axial-Ratio Bandwidth, Xiulong Bao, Max Ammann

Articles

A circularly polarised printed dipole-like antenna employing asymmetrical arms and an orthogonal slit in the ground plane is presented. It is fed by a stepped microstrip line which connects to the shorter arm. By utilising surface currents on the asymmetrical arms and the orthogonal feedline structure, circular polarisation is realised. Experimental and numerical data are in agreement and the measured results show a fractional impedance bandwidth of 41.3% (1.77–2.69 GHz) and a wide axial-ratio bandwidth of 38.4% (1.81–2.67 GHz).

Effect Of Ankle Orientation On Heel Loading And Knee Stability For Post-Stroke Individuals Wearing Ankle-Foot Orthoses, M. Barbara Silver-Thorn

Biomedical Engineering Faculty Research and Publications

Background: Those who experience lower extremity weakness or paralysis following a stroke often exhibit gait deviations caused by the inability to completely lift their foot during swing. An ankle-foot orthosis (AFO) is commonly prescribed for individuals post stroke with this mobility impairment.

Study design: Randomized controlled trial.

Objectives: To determine whether significant differences could be observed in post-stroke individuals ambulating with an experimental AFO set at three different ankle orientations.

Methods: Gait analysis was conducted for eight post-stroke individuals ambulating with an experimental AFO set in three different randomly selected ankle orientations: 5° dorsiflexion, 5° plantarflexion, and neutral alignment. Temporospatial …

Compressibility Effects Of Extended Formation Flight, Andrew Ning, Ilan Kroo

Faculty Publications

Aircraft flown in formations may realize significant reductions in induced drag by flying in regions of wake upwash. However, most transports fly at transonic speeds and compressibility effects in formation flight are not well understood. This study uses an Euler solver to analyze the inviscid aerodynamic forces and moments of transonic wing/body configurations flying in a 2-aircraft formation. We consider formations with large streamwise separation distances (10-50 wingspans) in an arrangement we term extended formation flight. Compressibility-related drag penalties in formation flight may be eliminated by slowing 2-3% below the nominal out-of-formation drag divergence Mach number, at fixed lift coefficient …

Wolf Ant, Gilbert L. Peterson, Christopher M. Mayer, Kevin Cousin

Faculty Publications

Ant colony optimization (ACO) algorithms can generate quality solutions to combinatorial optimization problems. However, like many stochastic algorithms, the quality of solutions worsen as problem sizes grow. In an effort to increase performance, we added the variable step size off-policy hill-climbing algorithm called PDWoLF (Policy Dynamics Win or Learn Fast) to several ant colony algorithms: Ant System, Ant Colony System, Elitist-Ant System, Rank-based Ant System, and Max-Min Ant System. Easily integrated into each ACO algorithm, the PDWoLF component maintains a set of policies separate from the ant colony's pheromone. Similar to pheromone but with different update rules, the PDWoLF policies …

Ir Nonlinear Absorption Leading To Laser-Induced Damage In Ge & Gasb, Torrey J. Wagner, Matthew J. Bohn, Ronald A. Coutu Jr., L. P. Gonzales, J. M. Murray, K. L. Schepler, S. Guha

Faculty Publications

Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 μm for the first time. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 μm and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al₂O₃ anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for ps or ns pulses, respectively. Wavelength-dependant …

Byu Indoor Flight System Circa June 2011, John C. Macdonald, Robert Leishman

Faculty Publications

This report documents the state of our indoor flight platform as of June 2011, the time of its first flight without a human in the loop. The report is intended to give enough detail that someone might have a reasonable hope of replicating our work from scratch.

Using Service Responsibility Tables To Supplement Uml In Analyzing E-Service Systems, Xin Tan, Steven Alter, Keng Siau

Research Collection School Of Computing and Information Systems

This paper proposes using Service Responsibility Tables (SRTs) as a tool in analyzing e-service systems. First it discusses difficulties and deficiencies of using formal modeling languages such as UML in analyzing e-service systems. It proposes using SRTs as an informal language and lightweight analytical tool to be used by business professionals in analyzing e-service systems. SRTs are based on a service value chain framework but do not rely on abstract concepts and constructs, and therefore can be used by business professionals to supplement UML. We suggest a set of heuristics for transforming SRTs into two key UML diagrams, thereby illustrating …

Supervisory Evolutionary Optimization Strategy For Adaptive Maintenance Schedules, Zhaoxia Wang, C. S. Chang

Research Collection School Of Computing and Information Systems

No abstract provided.

Online Fault Detection Of Induction Motors Using Frequency Domain Independent Components Analysis, Zhaoxia Wang, C. S. Chang

Research Collection School Of Computing and Information Systems

This paper proposes an online fault detection method for induction motors using frequency-domain independent component analysis. Frequency-domain results, which are obtained by applying Fast Fourier Transform (FFT) to measured stator current time-domain waveforms, are analyzed with the aim of extracting frequency signatures of healthy and faulty motors with broken rotor-bar or bearing problem. Independent components analysis (ICA) is applied for such an aim to the FFT results. The obtained independent components as well as the FFT results are then used to obtain the combined fault signatures. The proposed method overcomes problems occurring in many existing FFT-based methods. Results using laboratory-collected …

A Feature Based Frequency Domain Analysis Algorithm For Fault Detection Of Induction Motors, Zhaoxia Wang, C. S. Chang, Zhang Yifan

Research Collection School Of Computing and Information Systems

This paper studies the stator currents collected from several inverter-fed laboratory induction motors and proposes a new feature based frequency domain analysis method for performing the detection of induction motor faults, such as the broken rotor-bar or bearing fault. The mathematical formulation is presented to calculate the features, which are called FFT-ICA features in this paper. The obtained FFT-ICA features are normalized by using healthy motor as benchmarks to establish a feature database for fault detection. Compare with conventional frequency-domain analysis method, no prior knowledge of the motor parameters or other measurements are required for calculating features. Only one phase …

Effect Of Dry Particle Coating On The Properties Of Cohesive Pharmaceutical Powders, Lauren Elizabeth Beach

Dissertations

Engineered particles, which have undergone surface modification via dry coating, have been previously shown to have improved flow and handling properties. The improvements in these properties can be applied and are very useful for a number of industrial applications, in this case the pharmaceutical industry. This work investigates the effect of dry particle coating to improve the flowability of cohesive active pharmaceutical ingredient (API) powders and their blends. Improving the flow properties of cohesive API powders can significantly improve their handling and subsequent use for pharmaceutical processes such as formulation and manufacturing processing operations. Although it has been shown that …

A 3-Dimensional Vascularized Cardiac Tri-Culture Model Using Chitosan Nanofiber Scaffolds, Ali Hussain

Dissertations

The development of an in vitro tissue model that can mimic the 3-dimenisonal (3-D) cellular architecture and mosaic of myocardial tissue holds great value for cardiac tissue engineering, modeling, and cardiovascular drug screening applications. The main objective of this project was to develop a 3-D vascularized cardiac tissue model in vitro for improved survival and function.

The cellular mosaic of the myocardial tissue demands the intricate integration of an extracellular matrix-like scaffold, cellular constituents, and biological factors. The first aim of the research was to fabricate and characterize a biodegradable chitosan nanofiber scaffold that would resemble the extracellular matrix (ECM) …

A Study Of Three Transition Metal Compounds And Their Applications, Zhen Qin

Dissertations

The La_5/8-yPr_yCa_3/8MnO₃ with colossal magnetoresistance (CMR) effect has a rich phase diagram and is well studied for its electronic phase separation phenomenon, where the ferromagnetic (FM) metal order co-exists and competes with the charge-ordered (CO) insulator phase. High Pr doping will favor the CO order, leading a sharp FM to CO dominated phase transition around Pr concentration of 0.3 and above. Hydrostatic pressure favors FM metallic order without damaging the sample and can be tuned continuously. In this study, pressurized-magnetic and resistivity measurements was done on a La_0.25Pr_0.375Ca_{0.375 …}

Electrodeless Electro Hydrodynamic Printing Of Personalized Drug Dosages, Ezinwa Okeoma Elele

Dissertations

There is compelling evidence that variability in drug efficacy in individuals depends on their genetic fingerprints. These observations have given rise to the concept of personalized therapy whose ultimate goal is to develop medicinal agents designed for each niche of the population and individual patients according to their genetic background. The drawback in current pharmaceutical technologies is that most processes are designed to target large population and are unable to meet the demand of small-scale manufacturing of tailored therapeutics with diverse range of physical properties. One of the major challenges lie in developing efficient and cost effective methods of manufacturing …

Magnetic Seeding Aggregation To Enhance The Removal Efficiency Of Tio2 Nanoparticles From Water, Ashish Dhananjay Borgaonkar

Dissertations

Engineered nanoparticles, such as titanium dioxide (TiO₂), are important building blocks for the evolution of nanotechnology in industries and commercial products. Ever so increasing use of the engineered nanoparticles is bound to result in a substantial fraction of these nanoparticles ending up in wastewater; or surface water and groundwater, which are sources of intake for drinking water treatment. Removal of these engineered nanoparticles in wastewater and drinking water treatment processes is a very important step towards the protection of environmental and public health as well as protecting water treatment units from fouling and other issues.

Experimental studies showed …

Deagglomeration And Mixing Via The Rapid Expansion Of High Pressure And Supercritical Suspensions, Daniel To

Dissertations

Nano-materials are the focus of many research activities due to the desirable properties imparted from their small grain size and high interfacial surface area. However, these materials are highly cohesive powders in the dry state and typically form large agglomerates, leading to a diminished surface area or even grain growth, which minimizes the effectiveness of these nanomaterials. This dissertation addresses the issue of mixing nanopowders constituents by deagglomerating them and achieving simultaneous mixing so that even after inevitable reagglomeration, the effectiveness of large interfacial surface area may be preserved.

Nano-particle mixtures were prepared using the environmentally benign dry mixing methods …

Study Of The Heating And Ignition Of Metal Powder By Electrostatic Discharge, Ervin Beloni

Dissertations

The objective of this work was to understand the processes that lead to ESD stimulated ignition events in metal powders. Several metals were studied: Mg, Al, and Ti. A commercially available ESD test device was adapted for the present experiments. The ESD current and voltage were measured using inductance coils; the data were used to determine the electric circuit impedance, and energy transferred to the powder. A mode of the powder ignition (individual particles vs. dust cloud), ignition delays, burn times, and velocities of ignited and ejected particles were determined from optical measurements.

It was determined that the ESD energy …

A Study Of The New York / New Jersey Coastal Water : Bio-Optical Characteristics Of The Harbor Estuary And The Effects Of Heavy Metals On Brown Tide Alga Of The Bight, Bin Wang

Dissertations

The New York / New Jersey (NY/NJ) coastal area is one of the most productive regions around the world and a major natural and scenic resource for New York and New Jersey. As a result of excessive nutrient loading in the water, algal blooms have been observed since 1950’s. The NY/NJ coastal area includes the NY/NJ Bight and the NY/NJ Harbor Estuary, and in the former, brown tides (Aureococcus anophagefferens) were first observed in 1985 becoming a more serious water quality problem over the last 25 years. The influence of micronutrients, namely trace metals, on A. anophagefferens that are widespread …

Efficient Packet Delivery In Modern Communication Networks, Nan Wang

Dissertations

Modern communication networks are often designed for diverse applications, such as voice, data and video. Packet-switching is often adapted in today’s networks to transmit multiple types of traffic. In packet-switching networks, network performance is directly affected by how the networks handle their packets. This work addresses the packet-handling issues from the following two aspects: Quality of Service (QoS) and network coding.

QoS has been a well-addressed issue in the study of IP-based networks. Generally, nodes in a network need to be informed of the state of each communication link in order to make intelligent decisions to route packets according to …

Optimizing Resource Allocation In Next-Generation Optical Access Networks, Jingjing Zhang

Dissertations

To meet rapidly increasing traffic demands caused by the popularization of Internet and the spouting of bandwidth-demanding applications, Passive Optical Networks (PONs) exploit the potential capacities of optical fibers, and are becoming promising future-proof access network technologies. On the other hand, for a broader coverage area and higher data rate, integrated optical and wireless access is becoming a future trend for wireless access. This thesis investigates three next-generation access networks: Time Division Multiplexing (TDM) PONs, Wavelength Division Multiplexing (WDM) PONs, and WDM Radio-Over-Fiber (RoF) Picocellular networks.

To address resource allocation problems in these three networks, this thesis first investigates respective …

Modeling Of Non-Uniform Hydrodynamics And Catalytic Reaction In A Solids-Laden Riser, Rajeshkumar Patel

Dissertations

The riser reactors are widely used in a variety of industrial applications such as polymerization, coal combustion and petroleum refinery because of the strong mixing of gas and solids that yields high heat and mass transfer rates, and reaction rates. In a Fluid Catalytic Cracking (FCC) process, the performance of riser reactor is strongly dependent on the interaction between the fluid and catalysts, since the reaction takes place on the active surface of the catalysts. This is why, the local coupling between hydrodynamics and reaction kinetics is critical to the development of riser reaction models. The local gas-solids flow structure …

Efficient Support Of Consistent Cyclic Search With Read-Copy-Update And Parallel Updates, Jonathan Walpole, Paul E. Mckenney

Computer Science Faculty Publications and Presentations

A method, system and computer program product for supporting concurrent updates to a shared data element group while preserving group integrity on behalf of one or more readers that are concurrently referencing group data elements without using locks or atomic instructions. Two or more updaters may be invoked to generate new group data elements. Each new data element created by the same up dater is assigned a new generation number that is different than a global generation number associated with the data element group and which allows a reader of the data element group to determine whether the new data …

Formation Of Silicon Nanodots Via Ion Beam Sputtering Of Ultrathin Gold Thin Film Coatings On Si, Osman El-Atwani, Sami Ortoleva, Alex Cimaroli, Jean Paul Allain

Birck and NCN Publications

Ion beam sputtering of ultrathin film Au coatings used as a physical catalyst for self-organization of Si nanostructures has been achieved by tuning the incident particle energy. This approach holds promise as a scalable nanomanufacturing parallel processing alternative to candidate nanolithography techniques. Structures of 11- to 14-nm Si nanodots are formed with normal incidence low-energy Ar ions of 200 eV and fluences above 2 x 10(17) cm(-2). In situ surface characterization during ion irradiation elucidates early stage ion mixing migration mechanism for nanodot self-organization. In particular, the evolution from gold film islands to the formation of ion-induced metastable gold silicide …

Underwater Localization And Tracking Of Physical Systems, Patrick E. Carroll

Master's Theses

In this paper, we investigate the problem of localizing an underwater sensor node basedon message broadcasting from multiple surface nodes. With the time-of-arrival measurementsfrom a DSP-based multicarrier modem, each sensor node localizes itself based on the traveltime differences among multiple senders to the receiver. Using one-way message passing, such asolution can scale to accommodate a large number of nodes in a network. We consider the issuefrom not only the physical layer, but also at the node processing layer by incorporating a trackingsolution. We present simulation results as well as preliminary testing results in a swimming poolwith both stationary and moving …

Dissolution Of Disintegrating Solid Dosage Forms In A Modified Dissolution Testing Apparatus 2, Shrutiben Rameshbhai Parekh

Theses

Dissolution tests are routinely carried out in the pharmaceutical industry to determine the dissolution rate of solid dosage forms. Dissolution testing serves as a surrogate for drug bioavailability through in vitro–in vivo correlation (IVIVR), and it additionally helps in guiding the development of new formulations and in assessing lot-to-lot consistency, thus ensuring product quality. The United States Pharmacopoeia (USP) Dissolution Testing Apparatus 2 is the device most commonly used for this purpose. Despite its widespread use, dissolution testing using this apparatus remains susceptible to significant error and test failures. There is documented evidence that this apparatus is sensitive to several …

Dissolution Testing Of Prednisone And Salicylic Acid Calibrator Tablets At Different Tablet Locations, Anandhavalavan Arulmozhi

Theses

Dissolution testing is routinely carried out in the pharmaceutical industry to determine the rate of dissolution of solid dosage forms. This test is one of the several tests that pharmaceutical companies typically conduct on oral dosage formulations (e.g., tablets) to determine compliance. The USP Dissolution Testing Apparatus 2 is the most common of the apparatuses listed in the USP. However, it has been shown previously that the dissolution profile of a tablet undergoing dissolution in the USP Dissolution Apparatus 2 can be affected by the tablet location in the apparatus.

In this work, the dissolution rates of both non-disintegrating tablets …

Digital Image Forensics, Fei Long

Theses

Digital image forensics is a relatively new research field that aims to expose the origin and composition of, and the history of processing applied to digital images. Hence, the digital image forensics is expected to be of significant importance to our modern society in which the digital media are getting more and more popular. In this thesis, image tampering detection and classification of double JPEG compression are the two major subjects studied. Since any manipulation applied to digital images changes image statistics, identifying statistical artifacts becomes critically important in image forensics. In this thesis, a few typical forensic techniques have …

Investigation Of The Potential Catalytic Activities Of Several Metal Organic Framework (Mof) Materials, Guangyu Zhang

Theses

Metal-organic frameworks (MOFs) are promising porous materials due to their high porosities, large apparent surface areas, tunable pore properties and selective uptake of small molecules. Many researches have been focused on developing new MOF structures and exploring their use in gas storage and separation. Only few studies investigated the catalytic properties of MOFs. In this study, catalytic properties are explored over several MOFs including zeolitic imidazolate framework-8 (ZIF-8), Ni(FA) and Zn(FA). These MOFs are used as catalyst supports for iron or platinum nanoparticles. The catalysts are prepared using incipient wetness impregnation method and characterized with Brunauer-Emmett-Teller (BET), pulse chemisorption, X-ray …

Thermodynamics Of Dna Hybridization On Surfaces, Terry J. Schmitt, Thomas A. Knotts Iv

Faculty Publications

Hybridization of single-stranded DNA (ssDNA) targets to surface-tethered ssDNA probes was simulated using an advanced coarse-grain model to identify key factors that influence the accuracy of DNA microarrays. Comparing behavior in the bulk and on the surface showed, contrary to previous assumptions, that hybridization on surfaces is more thermodynamically favorable than in the bulk. In addition, the effects of stretching or compressing the probe strand were investigated as a model system to test the hypothesis that improving surface hybridization will improve microarray performance. The results in this regard indicate that selectivity can be increased by reducing overall sensitivity by a …