Engineering Commons^™

Rotorcraft Smoothing Via Linear Time Periodic Methods, Christopher S. Schulz

Theses and Dissertations

This research presents the development of an on line linear time periodic rotor vibration controller. The Cramer-Rao bound is developed for a linear time periodic system in order to identify the quality of identified system parameters, which are used in system models for controller development. The methods developed in this work allow model parameters can be verified for accuracy and likewise adjusted to improve controller accuracy.

Simulations Of Intracellular Calcium Release In Response To High-Intensity, Ultrashort Electric Pulse, Anh Nguyen

Electrical & Computer Engineering Theses & Dissertations

Calcium modulation is an important signaling process and could even contribute to cell apoptosis through ionic-induced perturbations in trans-membrane potential at the mitochondria. In this research, the numerical study constitutes a first step in quantitatively probing the time- and spatially-dependent modulation of calcium dynamics through the application of external electrical fields. The research uses both widely accepted deterministic continuum and discrete stochastic intracellular calcium models coupling with external electric field, with a focus on high-intensity ultrashort pulse electrical field.

For deterministic continuum intracellular calcium models with electric field assisted, numerical simulations for electrically induced, intra-cellular calcium-release from the endoplasmic reticulum …

Old Dominion University Space Systems Engineering Competency Development To Accommodate Orbital Flight Projects, Ersin Ancel

Mechanical & Aerospace Engineering Theses & Dissertations

Undergraduate engineering students in Old Dominion University's Batten College of Engineering and Technology have been engaged in the design, development, testing and flight of scientific sounding rocket payloads since 2004. During that time, two payloads have flown and a third payload has nearly achieved flight-ready status. The sophistication achieved by the flight-ready payload has resulted from the evolution of a rather rigorous space system design process that requires student involvement over periods of time that are much longer than those typically associated with an -undergraduate design course sequence.

In order to acquire the expected level of definition and reliability for …

Linear And Nonlinear Responses Of Isotropic Beams Under Concentrated Random Loads Unsynchronized In Time, Ravi Putrevu

Mechanical & Aerospace Engineering Theses & Dissertations

Large-amplitude random response of slender isotropic beams is studied using finite element analysis. The random load is assumed to be a stationary ergodic random Gaussian excitation with white noise characteristics. The loading is considered for three cases, namely synchronized, anti-synchronized, and unsynchronized in time. The linear response of beams is studied for the simply-supported and clamped-simply support conditions at the two ends. The non-linear response is, however, limited only to the simply-supported condition. There are no analytical solutions to the linear and non-linear responses of beams under concentrated random loads unsynchronized in time. The deflections due to unsynchronized loads are …

A Design Of Experiments Approach To Deck Flow Characterization On An Aircraft Carrier, Yugapriya Sivanesan Wing

Mechanical & Aerospace Engineering Theses & Dissertations

A wind tunnel model of an aircraft carrier was used to make air wake measurements. Particle image velocimetry measurements of turbulence intensity were made on a center plane intersecting the angled deck of the aircraft carrier. The factors of interest for the study were model pitch, yaw, island location, and island type. Two island types were used, a representative shape of current designs and an ideal streamlined airfoil shape. Each factor was studied at two levels in order to provide linear models using a Design of Experiments factorial design. From the data for each experimental combination, regression models for turbulence …

Context Sensitive Solutions For Construction And Maintenance, Theodore Hopwood Ii, Donald L. Hartman, Jerry G. Pigman

Kentucky Transportation Center Research Report

The objective of this research was to conduct a survey to assess the state of practice related to state highway agencies (SHAs) implementing context sensitive solutions including its application in Construction and Maintenance and to prepare a workshop enabling SHA officials to adopt practices promoting context sensitivity beyond Planning and Design.

Deliverables from the study efforts include a survey summary of context sensitive solutions and workshop materials/presentation suitable for use in training a wide range of SHA personnel working in Construction and Maintenance.

Fiber-Optic Strain Gauge With High Resolution And Update Rate, Fernando Figueroa, Ajay Mohan Mahajan, Mohammad Sayeh, Bradley Regez

Mechanical Engineering Faculty Research

An improved fiber-optic strain gauge is capable of measuring strains in the approximate range of 0 to 50 microstrains with a resolution of 0.1 microstrain. (To some extent, the resolution of the strain gauge can be tailored and may be extensible to 0.01 microstrain.) The total cost of the hardware components of this strain gauge is less than $100 at 2006 prices. In comparison with prior strain gauges capable of measurement of such low strains, this strain gauge is more accurate, more economical, and more robust, and it operates at a higher update rate. Strain gauges like this one are …

"Smart" Sensor Module, Ajay Mohan Mahajan

Mechanical Engineering Faculty Research

An assembly that contains a sensor, sensor-signal-conditioning circuitry, a sensor-readout analog-to-digital converter (ADC), data-storage circuitry, and a microprocessor that runs special-purpose software and communicates with one or more external computer(s) has been developed as a prototype of "smart" sensor modules for monitoring the integrity and functionality (the "health") of engineering systems. Although these modules are now being designed specifically for use on rocket-engine test stands, it is anticipated that they could also readily be designed to be incorporated into health-monitoring subsystems of such diverse engineering systems as spacecraft, aircraft, land vehicles, bridges, buildings, power plants, oilrigs, and defense installations. The …

Fabrication Of Ankle-Foot Orthoses Using Selective Laser Sintering Technology, Allison Kinney, M. C. Faustini, Richard R. Neptune, R. H. Crawford, S. J. Stanhope

Mechanical and Aerospace Engineering Faculty Publications

Passive dynamic ankle-foot orthoses (AFOs) are often prescribed to improve gait performance for those with various neuromuscular disorders. Designs and materials used for AFOs range from simple polypropylene braces to advanced custom carbon fiber dynamic AFOs that passively store and release mechanical energy during gait. AFO designs vary in the shape and length of the foot component as well as the stiffness and length of the tibial component, depending on the desired functional outcomes. However, the current fabrication technology is not ideally suited for refined customization of AFO characteristics to optimize performance, or for rapid lowcost, high volume manufacturing and …

Industrial Solid-State Energy Harvesting: Mechanisms And Examples, Matthew Kocoloski, Carl Eger, Robin Mccarty, Kevin P. Hallinan, J. Kelly Kissock

Mechanical and Aerospace Engineering Faculty Publications

This paper explores the potential for solid-state energy harvesting in industrial applications. In contrast to traditional heat recovery, the output of solid-state devices is electricity, which can be readily used in virtually any plant. The progress in harvesting waste heat via thermoelectric and thermionic generators is described. With second law efficiencies now approaching 50% and 80% respectively, we show that these technologies are on the cusp of practical use. Finally, we present an example of energy harvesting using thermionic devices in an industrial application. The example considers energy harvesting from a furnace at a glass manufacturing facility where exhaust gases …

Use Of Pp-G-Ma Prepared By Solution Process As Compatibilizerin Polypropylene/Polyamide 6 Blends, S Chongprakobkit, M Opaprakasit, S Chuayjuljit

Journal of Metals, Materials and Minerals

In this work, polypropylene grafted maleic anhydride (PP-g-MA) prepared by solution process was used as a compatibilizer for polypropylene (PP)/polyamide 6 (PA6) blends. PP with melt flow index (MFI) of 10 g/10 min was grafted with maleic anhydride (MA) using benzoyl peroxide (BPO) as an initiator and toluene as a solvent. The effects of BPO and MA concentration on the grafting degree of MA onto PP were studied. The grafting degree was determined by a back-titration procedure whereas the formation of graft copolymers was confirmed by FT-IR technique. It was found that the maximum extent of grafting achieved was 0.87%. …

Analysis Of The Influence Of The Loading Rate On The Mechanical Properties Of Microalloyed Steel, M Mihalikova

Journal of Metals, Materials and Minerals

The aim of this paper is to analyse the influence of the loading rate in the range from 1 to 1000 mm/min, which corresponds to the tensile machine working range, on the strength properties and the formability characteristics obtained on standard and notched test bars made of steel strips. The combination of the loading rate and the test bar type made it possible to obtain the relationship of monitored variables in the strain rate interval from 10-4 to 10 s-1. In this interval, the strength properties of the tested strips thickness of 1, 1.5 and 1.8 mm increase exponentially, but …

Effect Of Solution Annealing Temperature On Structure And Mechanical Properties Of En Aw 2024 Aluminium Alloy, M Fujda, R Mišičko, L Rusňáková, M Sojko

Journal of Metals, Materials and Minerals

The effect of solution annealing temperature on the change of microstructural and mechanical properties of EN AW 2024 aluminium alloy was investigated using a metallographic analysis, Vickers hardness measurement and tensile test. An intensive growth of solid solution grains was the result of the increase of solution annealing temperature by the finely dispersed particles dissolved during applied annealing process. The role of these finely dispersed particles was to inhibit the recrystallization process and grain growth of solid solution matrix through its pinning effect on the migrated solid solution grain boundaries. Observed changes of the microstructure involved the strength decline and …

Surface Treatment Of Powder Material By Metal Coatings - Study Of Corrosion Properties, Z Fečková

Journal of Metals, Materials and Minerals

Coatings by one-component Ni and two-component Ni-Co were electrodeposited onto Fe powder particles from a sulphate-based electrolyte. The coatings were deposited under galvanostatic conditions at 25o C. A fluidized bed arrangement was applied. The influence of cathodic current intensity and electrolysis time on the composition of metal coating was studied. The amount of deposited metals increased with the current intensity and with the electrolysis time. Scanning electron microscope and optical microscope were used to characterize the metal coatings. Voltammetric measurements have been conducted in order to characterize the electrochemical behaviour of Ni and Ni - Co coatings in two corrosion …

Powder Injection Moulding Of Cemented Carbides: Feedstock Preparation And Injection Moulding, N Chuankrerkkul, P F. Messer, H A. Davies

Journal of Metals, Materials and Minerals

A composite binder system, successfully developed earlier for powder injection moulding of stainless steels, CoCrMo and NiCrSiB alloys, has been adapted for tungsten carbide-cobalt (WC-Co) cemented carbides. The binder consists of a major fraction of polyethylene glycol (PEG), which can be removed rapidly by leaching with water, a minor fraction of a finely dispersed polymethyl methacrylate (PMMA), which retains rigidity of the components and sometimes with stearic acid (SA) to act as a lubricant. The adjustments made to powder characteristics, binder compositions and process parameters to achieve successful injection moulding are reported. Feedstocks containing a powder loading of the WC-Co …

Fatigue Performance Enhancement Of Steels Using Mechanical Surface Treatments, P Juijerm, I Altenberger

Journal of Metals, Materials and Minerals

Mechanical surface treatments (mainly deep rolling) were performed on various steels, such as austenitic stainless steel AISI 304 and normalized plain carbon steel SAE 1045. To evaluate the effectiveness of the mechanical surface treatments, mechanically surface treated specimens were cyclically deformed at room temperature using push-pull stress-controlled fatigue and compared to the non-surfacetreated condition as a reference state. Additionally, the concept, methods and effect of selected mechanical surface treatments will also be addressed in this paper. It was found that mechanical surface treatments can dramatically enhance the fatigue performance of metallic materials as compared to the non-surface-treated condition due to …

Glassification Of Electric Arc Furnace Dust By Using Fly Ash Or Bagasse Ash, S Polsilapa, P Wangyao

Journal of Metals, Materials and Minerals

Electric arc furnace (EAF) dusts contain significant quantities of iron and zinc found almost entirely as iron oxide, zinc oxide and zinc ferrite. The dust has been classified as a hazardous waste due to the relative high lead, cadmium and hexavalent chromium contents. An option for treating EAF dust with an economic and uncomplicated process is by using ashes. Silica in ashes has the ability to incorporate a variety of elements in a nonleachable form in the dust. In this study, the EAF dust was mixed with fly ash or bagasse ash in several ratios. All mixed samples were heated …

Microstructural Characterization Of Aluminum Powder Liquid Coating On In 738 Superalloy, P Visuttipitukul, N Limvanutpong, V Krongtong, P Wangyao

Journal of Metals, Materials and Minerals

The powder liquid coating method was proposed for aluminizing of nickel-based superalloy grade IN738 in this study. Slurries for the coating consisted of aluminum and alumina (Al2O3) powder with various weight ratios in the range from 3:7 to 10:0. The slurries were pasted onto the IN738 specimens, which were subsequently dried and heated under argon atmosphere. Macrostructures of coated samples were observed. Surface and cross-sectional microstructures were studied by OM and SEM. Qualitative analysis and composition mapping were analyzed by EDS. Phase identification of coated surface was done by GIXD, at the incident angle of 2 degrees. The results showed …

Om Study Of Effect Of Hip And Heat Treatments On Microstructural Restoration In Cast Nickel-Based Superalloy, Gtd-111, P Wangyao, V Krongtong, W Homkrajai, N Panich, G Lothongkum

Journal of Metals, Materials and Minerals

The present work aims at studying and searching for the effect of repairing conditions on microstructural restoration. It also seeks to investigate into the most suitable and practicable repairing condition, which could provide the desired microstructural characteristics by rejuvenation method of hot isostatic pressing (HIP), followed by 12 heat treatment conditions for long-term serviced gas turbine blades, cast nickel-based superalloy grade GTD-111 operated by Electricity Generating Authority of Thailand (EGAT). During solution treatment, coarse carbides and over-exposed coarse gamma prime precipitates, which had formed previously during service, would dissolve into the matrix. Then specimens were processed through a series of …

Ceg 220-01: Introduction To C Programming For Engineers - I, Ronald F. Taylor

Computer Science & Engineering Syllabi

This course provides a general introduction to computers as a problem-solving tool using the C programming language. Emphasis is on algorithms and techniques useful to engineers. Topics include data representation, debugging, and program verification. Some programming assignments may involve complex arithmetic and trigonometric and exponential functions. 4 credit hours.

Spice-Compatible Cavity And Transmission Line Model For Power Bus With Narrow Slots, Gang Feng, Yaojiang Zhang, James L. Drewniak, Lin Zhang

Electrical and Computer Engineering Faculty Research & Creative Works

Segmental lumped circuits are derived from coupled transmission line model for a narrow slot on the power bus. Both electric and magnetic coupling are taken into account by distributed inductances and capacitances. Then a SPICE- compatible circuit model for the power bus with the narrow slot is proposed. In this model, the segmental lumped circuits are connected to the equivalent circuit, which is derived by a hybrid cavity model and segmentation method for irregular power/ground planes. The model is validated by comparing with the calculations of finite element method (FEM) for the self or mutual impedances of the two port …

Steady State Formulation Of Facts Devices Based On Ac/Ac Converters, J. M. Ramirez, J. M. Gonzalez, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

Here the analysis on the inclusion of a pulse width modulated (PWM) ac link unified power flow controller into a power flow program is discussed. Similarly, a PWM series compensator is connected to the power system to regulate the active power flow on the corresponding transmission line. Details of the Newton-Raphson's power flow algorithm are exhibited. Results of simulation are presented on a 39-buses power system.

A Three-Dimensional Fdtd Subgridding Algorithm With Separated Temporal And Spatial Interfaces And Related Stability Analysis, Kai Xiao, David Pommerenke, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

A finite-different time-domain subgrid algorithm locally refines the mesh at regions requiring higher resolution. A novel separation of spatial and temporal subgridding interfaces is presented that allows implementing a novel spatial subgridding method and investigating the stability of each subalgorithm individually. Details are given for a spatial subgridding algorithm having a 1:3 mesh ratio. In the spatial subgridding algorithm, the fine-mesh is constructed with a recessed interface and the interpolation scheme is designed to be symmetric to maintain the stability of the update process. The stability of the spatial subgridding algorithm is analyzed with a matrix method. Numerical examples showing …

Advanced Control And Analysis Of Cascaded Multilevel Converters Based On P-Q Compensation, Shuai Lu, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

This paper introduces new controls for the cascaded multilevel power converter. This converter is also sometimes referred to as a ldquohybrid converterrdquo since it splits high-voltage/low-frequency and low-voltage/pulsewidth-modulation (PWM)-frequency power production between ldquobulkrdquo and ldquoconditioningrdquo converters respectively. Cascaded multilevel converters achieve higher power quality with a given switch count when compared to traditional multilevel converters. This is a particularly favorable option for high power and high performance applications such as naval ship propulsion. This paper first presents a new control method for the topology using three-level bulk and conditioning inverters connected in series through a three-phase load. This control avoids …

Application Of Millimeter Wave, Eddy Current And Thermographic Methods For Detection Of Corrosion In Aluminum Substrate, Mohammad Tayeb Ahmad Ghasr, Adam C. Ryley, Sergey Kharkovsky, R. Zoughi, Gary Steffes

Electrical and Computer Engineering Faculty Research & Creative Works

Aluminum structures exposed to the elements are susceptible to corrosion. Corrosion may cause various mechanical and structural deficiencies such as material thinning. It is desirable to rapidly detect and evaluate the properties of an aluminum substrate early in the corrosion process to avoid costly maintenance actions later. There are several nondestructive testing methods for this purpose. To investigate capabilities of millimeter wave, conventional eddy current, and flash thermography techniques for detection of large corrosion areas in aluminum substrates, two corroded samples were inspected with and without dielectric coating (appliqué). This paper presents the results of the c-scan imaging of these …

Reinforcement Learning Based Output-Feedback Control Of Nonlinear Nonstrict Feedback Discrete-Time Systems With Application To Engines, Peter Shih, Jonathan B. Vance, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning based output-adaptive neural network (NN) controller, also referred as the adaptive-critic NN controller, is developed to track a desired trajectory for a class of complex nonlinear discrete-time systems in the presence of bounded and unknown disturbances. The controller includes an observer for estimating states and the outputs, critic, and two action NNs for generating virtual, and actual control inputs. The critic approximates certain strategic utility function and the action NNs are used to minimize both the strategic utility function and their outputs. All NN weights adapt online towards minimization of a performance index, utilizing gradient-descent based rule. …

Early Time Charge Replenishment Of The Power Delivery Network In Multi-Layer Pcbs, Giuseppe Selli, Matteo Cocchini, James L. Knighten, Bruce Archambeault, Jun Fan, Samuel R. Connor, Antonio Orlandi, James L. Drewniak

Electrical and Computer Engineering Faculty Research & Creative Works

The investigation of decoupling issues has been extensively treated in the literature in both the frequency and the time domain [1-9]. The two domains describe from different perspectives the same physical phenomenon, being related by a Fourier transform. In this article, well known decoupling issues usually addressed in the frequency domain [1,2] are discussed in the time domain. Moreover, some modeling issues related to the cavity model approach are discussed and, in particular, the circuit extraction feature associated with this methodology is utilized throughout the article to carry out the time domain simulations within a SPICE based-tool. The depletion of …

Engineering Of Absorbing Gaskets Between Metal Plates, Marina Koledintseva, Sandeep K. R. Chandra, James L. Drewniak, James A. Lenn

Electrical and Computer Engineering Faculty Research & Creative Works

Engineering of absorbing materials for gaskets that would be used between two metal plates to reduce electromagnetic emissions and improve immunity of electronic equipment is considered. An analytical model of a composite based on the Maxwell Garnett formulation for multiphase mixtures, as well as the shielding effectiveness of this material, are presented. The full-wave numerical computational results for the structure consisting of two overlapping metal plates and an engineered gasket composite material in the place of the overlap are presented.

Identification Of Induction Machines Stator Currents With Generalized Neurons, Jing Huang, Ganesh K. Venayagamoorthy, Keith Corzine

Electrical and Computer Engineering Faculty Research & Creative Works

A new approach to identify the nonlinear model of an induction machine using two generalized neurons (GNs) is presented in this paper. Compared to the multilayer perceptron feedforward neural network, a GN has simpler structure and lesser requirement in terms of memory storage which is makes it attractive for hardware implementation. This method shows that with less number of weights, GN is able to learn the dynamics of an induction machine. The proposed model is made by two coupled networks. A modified particle swarm optimization algorithm is designed to solve this distinctive GN training problem. A pseudo-random binary sequence signal …

Intelligent Local And Hierarchical Control Of Facts Devices, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents an overview of the applications of intelligent control techniques on local and hierarchical control of FACTS devices. These control techniques are superior to the conventional linear/nonlinear control schemes in the sense that they are independent of any mathematical model of the power system to be controlled. In addition, they do not depend on the operating conditions and the configuration of the system to which the FACTS device is connected. A static compensator (STATCOM) is used as the example in order to compare the performances of the proposed intelligent controllers with those of their linear counterparts. Nevertheless, the …