Engineering Commons^™

Volume Holographic Optical Elements, Ching-Cherng Sun, Partha P. Banerjee

Partha Banerjee

The final two papers are concerned with the analysis of novel holograms. Banerjee et al. investigate holographic recording and reconstruction for edge-lit holograms recorded in a 90-degree geometry. Various cases of recording and readout that incorporate propagational diffraction have been modeled. It is shown that the 90-degree geometry can result in beam shaping, as evidenced through preliminary experimental results with photorefractive lithium niobate. Nguyen et al. propose a new approach for designing computer-generated holograms. An artificial neural network is used to initiate the genetic algorithm so that the high computation cost of genetic algorithms for synthesizing holograms is significantly reduced …

Chemical Dynamics Of Aluminum Nanoparticles In Ammonium Nitrate And Ammonium Perchlorate Matrices: Enhanced Reactivity Of Organically Capped Aluminum, William K. Lewis, Barbara A. Harruff-Miller, Joseph R. Gord, Andrew T. Rosenberger, Thomas M. Sexton, Elena A. Guliants, Christopher E. Bunker

Elena A. Guliants

Aluminum nanoparticles have been a subject of active investigation in recent years because of their potential to enhance the energy content of energetic materials. The associated kinetics of the chemical reaction and energy release are, in many cases, governed by the properties of the passivation layer protecting the particle rather than those of the underlying metal core. The passivation layer of Al particles is typically an oxide shell several nanometers thick, but other possibilities are now available. We have previously developed synthesis routes to produce air-stable Al nanoparticles that are capped by oleic acid. In the present study, we examine …

Carbon Nanoparticles As Visible-Light Photocatalysts For Efficient Co2 Conversion And Beyond, Li Cao, Sushant Sahu, Parambath Anilkumar, Christopher E. Bunker, Juan Xu, K. A. Shiral Fernando, Ping Wang, Elena A. Guliants, Kenneth N. Tackett Ii, Ya-Ping Sun

Elena A. Guliants

Increasing atmospheric CO2 levels have generated much concern, driving the ongoing carbon sequestration effort. A compelling CO2 sequestration option is its photocatalytic conversion to hydrocarbons, for which the use of solar irradiation represents an ultimate solution. Here we report a new strategy of using surface-functionalized small carbon nanoparticles to harvest visible photons for subsequent charge separation on the particle surface in order to drive the efficient photocatalytic process. The aqueous solubility of the catalysts enables photoreduction under more desirable homogeneous reaction conditions. Beyond CO2 conversion, the nanoscale carbon-based photocatalysts are also useful for the photogeneration of H2 from water under …

Optimal Scheduling Of A Microgrid With Demand Response Resources, Daniela Proto, Guido Carpinelli, Fabio Mottola

Daniela Proto

Exponential Weighted Method And A Compromise Programming Method For Multi-Objective Operation Of Plug-In Vehicle Aggregators In Microgrids, Pierluigi Caramia, Guido Carpinelli, Daniela Proto, Fabio Mottola

Daniela Proto

No abstract provided.

Unsteady Mixed Convection In A Porous Media Filled Lid-Driven Cavity Heated By A Semi-Circular Heaters, Saad Mekhilef

Saad Mekhilef

A computational study has been performed on natural convection heat transfer and fluid flow in a porous media filled enclosure with semi-circular heaters by using finite element method. The ceiling of the cavity moves with a constant velocity and it is insulated. Temperature of vertical walls is lower than that of heaters. Results are presented via streamlines, isotherms, average Nusselt numbers and cross sectional velocity for different governing parameters such as Richardson number, Darcy number and dimensionless time. It is observed that both circulation of the flow and heat transfer is strongly affected with time increment and Darcy number inside …

Unsteady Natural Convection In Al2o3–Water Nanoliquid Filled In Isosceles Triangular Enclosure With Sinusoidal Thermal Boundary Condition On Bottom Wall, Saad Mekhilef

Saad Mekhilef

Unsteady natural convection heat transfer in an isosceles triangular enclosure filled with Al2O3 nanoparticle is studied by using finite element method. The bottom of the isosceles triangular cavity is heated non-uniformly and temperature of the inclined wall is lower than that of the bottom wall. The governing parameters are Rayleigh number, solid volume fraction, aspect ratio (H/L) of the enclosure and dimensionless-time. It is found that addition of the nanoparticle into base fluid (water) affects both heat transfer and fluid flow. Heat transfer increases with addition of nanoparticle and increasing of Rayleigh number. Conduction mode of heat transfer becomes dominant …

Point Of Common Coupling (Pcc) Voltage Control Of A Grid-Connected Solar Photovoltaic (Pv) System, Brian Perera, Philip Ciufo, Sarath Perera

Dr Philip Ciufo

In future low voltage grids, with multiple inverter interfaced sources connected, voltage regulation may become a necessary task. The potential exists for inverter interfaced sources to be deployed to regulate the voltage at the point of common coupling (PCC) of each inverter interfaced sources. The PCC voltage regulation is attainable with inverter interfaced sources by dynamically controlling the amount of reactive power injected to the power distribution grid by individual systems. In the current research, a closed-loop controller is proposed to regulate the PCC voltage of a solar photovoltaic (PV) system that is connected to a single-phase power distribution feeder …

Dynamic Companion Harmonic Circuit Models For Analysis Of Power Systems With Embedded Power Electronics Devices, H. Garcia, M. Madrigal, B. Vyakaranam, Rick Rarick, F. Eugenio Villaseca

F. Eugenio Villaseca

In this paper a methodology that extends the dynamic harmonic domain (DHD) analysis of large networks is presented. The method combines DHD analysis and discrete companion circuit modeling resulting in a powerful analytic technique called dynamic companion harmonic circuit modeling. It provides for a complete dynamic harmonic analysis of the system while preserving the advantages of discrete companion circuit models. The methodology is illustrated by its application to a three-node power system, where reactive power compensation is achieved using a fixed-capacitor, thyristor-controlled reactor (FC-TCR) and its control system.

Low-Cost Stereo Vision On An Fpga, Chris A. Murphy, Daniel Lindquist, Ann Marie Rynning, Thomas Cecil, Sarah Leavitt, Mark L. Chang

Mark L. Chang

We present a low-cost stereo vision implementation suitable for use in autonomous vehicle applications and designed with agricultural applications in mind. This implementation utilizes the Census transform algorithm to calculate depth maps from a stereo pair of automotive-grade CMOS cameras. The final prototype utilizes commodity hardware, including a Xilinx Spartan-3 FPGA, to process 320times240 pixel images at greater than 150 frames per second and deliver them via a USB 2.0 interface.

Evaluation And Design Optimization Of Piezoresistive Gauge Factor Of Thick-Film Resistors, Sherra E. Kerns, David V. Kerns, C Song, J. L. Davidson, W. P. Kang

Sherra E. Kerns

On the basis of the analysis of all the thick- film design methodologies, the authors designed a test sample on which four different length-over-width ratios of resistors were designed. They found that the length-over-width ratio will substantially affect the gauge factor in some cases, in contrast to prior research. This can be modeled to generate a linear predictive model, The sensors designed on the insulator and the sensors underneath the insulator were also studied in order to simulate the multilayer hybrid technology and study the effects of insulator-resistor-substrate surface interaction. It is demonstrated that design techniques can affect the strain …

Measurement Of Metal Migration On Thick Film Piezoresistors And Their Termination, David V. Kerns, C Song, J L. Davidson, D L. Kinser

David V. Kerns

Metal migration from the thick-film termination can affect not only the electrical characteristics but also the gauge factor or piezoresistive coefficient of thick-film sensors. Four sets of sensors with different ratios were designed to test the influence of the terminal metal migration effects on the gauge factors and resistivity of thick-film resistors. In all the cases, the shortest resistors have a lower gauge factor and a large deviation ofresistances. The longer resistors will have better electrical parameters. SEM (scanning electron microscope) studies showed this interaction at the interface between the terminal and the resistor. The same distance of terminal diffusion …

Evaluation And Design Optimization Of Piezoresistive Gauge Factor Of Thick-Film Resistors, Sherra E. Kerns, David V. Kerns, C Song, J. L. Davidson, W. P. Kang

David V. Kerns

On the basis of the analysis of all the thick- film design methodologies, the authors designed a test sample on which four different length-over-width ratios of resistors were designed. They found that the length-over-width ratio will substantially affect the gauge factor in some cases, in contrast to prior research. This can be modeled to generate a linear predictive model, The sensors designed on the insulator and the sensors underneath the insulator were also studied in order to simulate the multilayer hybrid technology and study the effects of insulator-resistor-substrate surface interaction. It is demonstrated that design techniques can affect the strain …

Risk-Based Critical Infrastructure Protection Priorities For Emp And Solar Storms, George H. Baker Iii

George H Baker

The Commission to Assess the Threat to the United States from Electromagnetic Pulse Attack has provided a compelling case for protecting civilian infrastructure against the effects of EMP. As with protecting infrastructure against any hazard, it will be important to take a risk-based priority approach for EMP, recognizing that it is fiscally impracticable to protect everything. In this regard, EMP is particularly challenging in that it interferes with electrical and electronic data, control, transmission, and communication systems organic to nearly all infrastructures in a simultaneous and wide-scale manner. And, for nuclear burst altitudes of 100s of kilometers, the exposed geography …

Investigation Of Stun Guns As Intentional Electromagnetic Interference (Emi) Sources, George H. Baker, Ryan C. Tuttle

George H Baker

Determined malefactors have demonstrated the use of common systems as effective weapons against civilian infrastructures, e.g. commercial jetliners used as kinetic weapons and cell phones used to trigger explosive devices. This undergraduate research project investigated the possibility of using readily available stun gun devices for electro-magnetic interference with or disruption of personal computers. At present, the system effects of high power electromagnetic sources are well recognized by world scientific and military communities. Former CIA Director John Deutch has said that, "the electron is the ultimate precision-guided weapon."1 There has been much research on the deleterious effects of pulsed voltages and …

Algorithme D’Elaboration D’Un Reseau Electrique A Gestion Optimale D’Ecoulement Des Puissances, Tarek Mesbah

Boukhemis Chetate

Un des baromètres (indicateurs du niveau d’évolution ) de développement d’un pays, est sa consommation en énergie électrique ; dont tout industrie et mode de vie des résidents en dépend. Partant sur ce point capital nous avons organisé la thèse afin de gérer le parc énergétique national d’une manière rationnelle. Cette étude peut servir dans la compréhension et l’analyse approfondie de l’état de la stabilité de notre réseau électrique, qui a montré sa fragilité après l’incident vécu le 03/02/2003, qui a prouvé l’urgence de prendre en charge toutes les insuffisances enregistrées pour éviter que cet incident se reproduise. La thèse …

Influence Of Overvoltages In Induction Motors Fed By Pwm Voltage Inverters On Power Efficiency, Boukhemis Chetate, Mohammed Tahar Belassel, Rachid Beguenane, Stéphane Simard

Boukhemis Chetate

No abstract provided.

New Technique Of One And Simultaneous Two Open-Switches Fault Automation Detection And Location In Two Level Three Voltage Inverter, Tarak Benslimane, Boukhemis Chetate

Boukhemis Chetate

No abstract provided.

Optimisation Des Régimes De Fonctionnement D'Un Moteur Asynchrone À Cage Entrainant Une Charge Variable, Malika Louanchi

Boukhemis Chetate

L’objectif de ce travail est l’optimisation du régime de fonctionnement des moteurs asynchrones lorsqu’ils sont sou chargés en minimisant le courant statorique absorbé en régime établit. La minimisation du courant statorique est obtenue en faisant varier la tension d’alimentation. Nous avons initialement procédé à la description et à la modélisation du moteur asynchrone, et à partir d’un schéma équivalent du moteur nous avons établit la relation liant le courant statorique minimal à la tension qui lui correspond. Pour la variation de la tension d’alimentation nous avons opté pour un gradateur triphasé à thyristors et pour un onduleur de tension à …

Commande Vectorielle Indirecte D'Un Moteur À Induction Par Logique Floue, Boukhemis Chetate , Aissa Kheldoun

Boukhemis Chetate

La commande vectorielle indirecte est actuellement la technique la plus utilisée pour contrôler la vitesse (ou la position) des actionneurs électriques à courant alternatif. Malheureusement les paramètres de la machine changent en raison de l'échauffement de ses parties ou à cause de l'interaction avec le mécanisme entraîné. Le présent travail, est consacré à l'application de la logique floue, d'une part, pour régler et adapter la constante de temps rotorique du moteur découplé par la technique à champ orienté et, d'autre part, en vue d'améliorer les performances correspondantes en cas de changement du moment d'inertie et d'application de la charge. Par …

Le Diagnostic Automatique Des Anomalies Des Systèmes Electromécaniques, Boukhemis Chetate

Boukhemis Chetate

Le fonctionnement optimal et continu des mécanismes industriels ne peut être envisagé sans la présence d’un système qui permet de prévenir (surveillance et interprétation) à l’état précoce les anomalies qui peuvent surgie au niveau des différents équipements et de diagnostiquer rapidement les pannes. Dans le système proposé en vue d’automatiser complètement le processus de diagnostic des ensembles moteurs asynchrones convertisseurs de fréquence et commande , et en vue de diminuer le temps d’analyse des défaillances et les coûts des interventions, le système expert est associé avec un sous –système de mesure, d’acquisition et de traitement de l’information (permettant l’observation des …