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Articles 12661 - 12690 of 21751

Full-Text Articles in Engineering

Superplasticity In Cast A356 Induced Via Friction Stir Processing, Z. Y. Ma, Rajiv S. Mishra, M. W. Mahoney Apr 2004

Superplasticity In Cast A356 Induced Via Friction Stir Processing, Z. Y. Ma, Rajiv S. Mishra, M. W. Mahoney

Materials Science and Engineering Faculty Research & Creative Works

Super plasticity was investigated in friction stir processed A356 alloy at temperatures of 470-570 °C and initial strain rates of 3x10 -4-1x10-1 s-1. Maximum superplastic elongation of 650% was obtained at 530 °C and an initial strain rate of 1x10-3 s-1 where a maximum strain rate sensitivity of 0.45 was observed. © 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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Metal Superplasticity Enhancement And Forming Process, Rajiv S. Mishra, Murray W. Mahoney Mar 2004

Metal Superplasticity Enhancement And Forming Process, Rajiv S. Mishra, Murray W. Mahoney

Materials Science and Engineering Faculty Research & Creative Works

A shaped metallic component is formed by friction stirring at least a segment of a single piece of bulk metal to impart superplasticity thereto and thereby yield a single superplastic metal blank from the single piece of bulk metal. The metal blank is then deformed by a metal deformation process such as forging, rolling, drawing, bending, extruding, gas forming, punching, and stamping.

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Bioactive Materials, D. E. Day, Erik M. Erbe, Marina Richard, Joshua A. Wojcik Mar 2004

Bioactive Materials, D. E. Day, Erik M. Erbe, Marina Richard, Joshua A. Wojcik

Materials Science and Engineering Faculty Research & Creative Works

Bioactive substantially silica-free glass material with a hydroxyapatite layer thereon is described, as well as methods for producing hydroxyapatite on a borate glass.

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Dynamic Contact Angles Under Evaporation, Robert M. Ybarra, Partho Neogi Mar 2004

Dynamic Contact Angles Under Evaporation, Robert M. Ybarra, Partho Neogi

Chemical and Biochemical Engineering Faculty Research & Creative Works

Wetting kinetics in the presence of heat transfer, evaporation, and Marangoni effect has been explored using a method used by Joanny and de Gennes [C. R. Acad. Sci. Ser. II 299, 279 (1984)]. The method solves for the dynamic contact angle alpha by equating the rate of surface work to the rate of dissipation. The result in the form of dynamic contact angle alpha as a function of capillary number Ca agrees well with existing experimental data. Qualitative comparisons have been made in cases where quantitative data do not exist. Finally, a form of contact line instability is predicted, for …

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Power Quality Enhancement Using Custom Power Devices [Book Review], Mariesa Crow Mar 2004

Power Quality Enhancement Using Custom Power Devices [Book Review], Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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A Switched Reluctance Machine-Based Starter/Alternator For More Electric Cars, Babak Fahimi, Ali Emadi, Raymond B. Sepe Mar 2004

A Switched Reluctance Machine-Based Starter/Alternator For More Electric Cars, Babak Fahimi, Ali Emadi, Raymond B. Sepe

Electrical and Computer Engineering Faculty Research & Creative Works

Switched reluctance machines (SRMs) are considered as serious candidates for starter/alternator (S/A) systems in more electric cars. Robust performance in the presence of high temperature, safe operation, offering high efficiency, and a very long constant power region, along with a rugged structure contribute to their suitability for this high impact application. to enhance these qualities, we have developed key technologies including sensor less operation over the entire speed range and closed-loop torque and speed regulation. the present paper offers an in-depth analysis of the drive dynamics during motoring and generating modes of operation. These findings will be used to explain …

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Estimative Current Mode Control Technique For Dc-Dc Converters Operating In Discontinuous Conduction Mode, Mehdi Ferdowsi, Ali Emadi Mar 2004

Estimative Current Mode Control Technique For Dc-Dc Converters Operating In Discontinuous Conduction Mode, Mehdi Ferdowsi, Ali Emadi

Electrical and Computer Engineering Faculty Research & Creative Works

A new control technique for DC-DC converters is introduced and applied to a boost converter operating in discontinuous conduction mode (DCM). In contrast to conventional control methods, the principal idea of the proposed control scheme is to obtain samples of the required signals and estimate the required switch-on time. The proposed technique is applicable to any converter operating in DCM, including power factor correctors (PFC), however, this letter mainly focuses on boost topology. In this letter, the main mathematical concept of a new control algorithm is introduced, as well as the robustness investigation of the proposed method with simulation and …

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Intelligent Control Schemes For A Static Compensator Connected To A Power Network, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley Mar 2004

Intelligent Control Schemes For A Static Compensator Connected To A Power Network, Salman Mohagheghi, Ganesh K. Venayagamoorthy, Ronald G. Harley

Electrical and Computer Engineering Faculty Research & Creative Works

Two intelligent controllers are designed for a static compensator (STATCOM) connected to a single machine infinite bus power system (SMIB): a novel nonlinear adaptive controller using artificial neural networks based on the indirect adaptive control technique and a Takagi-Sugeno type fuzzy controller. Both schemes provide nonlinear adaptive control with better performance compared to the conventional PI controllers. Simulation results are presented to compare the performances of these controllers with that of the conventional PI controllers.

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Annealing-Induced Full Amorphization In A Multicomponent Metallic Film, J. P. Chu, C. T. Liu, T. Mahalingam, S. F. Wang, Matthew O'Keefe, Benedict Y. Johnson, C. H. Kuo Mar 2004

Annealing-Induced Full Amorphization In A Multicomponent Metallic Film, J. P. Chu, C. T. Liu, T. Mahalingam, S. F. Wang, Matthew O'Keefe, Benedict Y. Johnson, C. H. Kuo

Materials Science and Engineering Faculty Research & Creative Works

We present direct experimental evidence that controllable amorphization and nanocrystallization during annealing of metastable films could serve as a precursor for exciting nanomaterials. The interesting discovery is that certain sputtered crystalline films become completely amorphous when annealed in the temperature range between the glass temperature and the crystallization temperature. Unlike other metallic glassy materials that exhibit annealing-induced devitrification, our good glass-forming films are transformed into various nanoscale and amorphous structures due to the annealing process. The formation of an amorphous phase gives rise to notable alterations in the electrical and mechanical properties of the film.

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Analyzing And Modeling Of Photobioreactors By Combining First Principles Of Physiology And Hydrodynamics, Hu Ping Luo, Muthanna H. Al-Dahhan Feb 2004

Analyzing And Modeling Of Photobioreactors By Combining First Principles Of Physiology And Hydrodynamics, Hu Ping Luo, Muthanna H. Al-Dahhan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Mixing in Photobioreactors is Known to Enhance Biomass Productivity Considerably, and Flow Dynamics Play a Significant Role in the Reactor's Performance, as They Determine the Mixing and the Cells' Movement. in This Work We Focus on Analyzing the Effects of Mixing and Flow Dynamics on the Photobioreactor Performance. based on Hydrodynamic Findings from the CARPT(Computer Automated Radioactive Particle Tracking) Technique, a Possible Mechanism for the Interaction between the Mixing and the Physiology of Photosynthesis is Presented, and the Effects of Flow Dynamics on Light Availability and Light Intensity Fluctuation Are Discussed and Quantitatively Characterized. Furthermore, a Dynamic Modeling Approach is …

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Male Breast Cancer During Finasteride Therapy [4], Shen C. Lee, Robert J. Ellis Feb 2004

Male Breast Cancer During Finasteride Therapy [4], Shen C. Lee, Robert J. Ellis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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Ccfss Technical Bulletin Spring 2004, Wei-Wen Yu Center For Cold-Formed Steel Structures Feb 2004

Ccfss Technical Bulletin Spring 2004, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Technical Bulletins (1993 - 2020)

No abstract provided.

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Ccfss News Spring 2004, Wei-Wen Yu Center For Cold-Formed Steel Structures Feb 2004

Ccfss News Spring 2004, Wei-Wen Yu Center For Cold-Formed Steel Structures

CCFSS Newsletters (1999 - 2008)

No abstract provided.

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Optical Characterization Of Ceramic Thin Films: Applications In Low-Temperature Solid Oxide Fuel-Cell Materials Research, Vladimir Petrovsky, Tatiana Petrovsky, Harlan U. Anderson, Brian P. Gorman Feb 2004

Optical Characterization Of Ceramic Thin Films: Applications In Low-Temperature Solid Oxide Fuel-Cell Materials Research, Vladimir Petrovsky, Tatiana Petrovsky, Harlan U. Anderson, Brian P. Gorman

Materials Science and Engineering Faculty Research & Creative Works

Characterization of thin film solid oxide fuel-cell materials can be difficult due to the range of porosities in electrodes and electrolytes as well as the nano-sized pores and particles. In this study, optical characterization techniques such as ultraviolet-visible transmission and reflection spectrophotometry are illustrated as methods for achieving information about the film density from the film refractive index as well as the film thickness. These techniques were used to investigate the sintering process of colloidal CeO2 on sapphire substrates and polymeric precursor-derived ZrO2:16%Y (YSZ) thin films on silicon over the temperature range 400-1000 °C, and the results were compared with …

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Common-Mode Current Due To A Trace Near A Pcb Edge And Its Suppression By A Guard Band, Yoshiki Kayano, Motoshi Tanaka, James L. Drewniak, Hiroshi Inoue Feb 2004

Common-Mode Current Due To A Trace Near A Pcb Edge And Its Suppression By A Guard Band, Yoshiki Kayano, Motoshi Tanaka, James L. Drewniak, Hiroshi Inoue

Electrical and Computer Engineering Faculty Research & Creative Works

The common-mode (CM) current due to a trace near a printed circuit board (PCB) edge, and its suppression by a guard band have been studied experimentally and with finite-difference time-domain (FDTD) modeling. As the guard band, copper tape is connected along the entire edge of the ground plane. First, a PCB electromagnetic interference (EMI) coupling path that results from the nonzero impedance of the PCB ground plane is discussed. As the trace is moved closer to the PCB edge, the CM current increases. Then, the effect of the guard band on the CM current is detailed. A guard band parallel …

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An Efficient Multirate Simulation Technique For Power-Electronic-Based Systems, Steven D. Pekarek, Oleg Wasynczuk, Eric A. Walters, Juri V. Jatskevich, Charles E. Lucas, Ning Wu, Peter T. Lamm Feb 2004

An Efficient Multirate Simulation Technique For Power-Electronic-Based Systems, Steven D. Pekarek, Oleg Wasynczuk, Eric A. Walters, Juri V. Jatskevich, Charles E. Lucas, Ning Wu, Peter T. Lamm

Electrical and Computer Engineering Faculty Research & Creative Works

A novel multirate method of simulating power-electronic-Based systems containing a wide range of time scales is presented. in this method, any suitable integration algorithm, with fixed or variable time-step, can be applied to the fast and/or slow subsystems. the subsystems exchange coupling variables at a communication interval that can be fixed or varied dynamically depending upon the state of the system variables. the proposed multirate method is applied to two example power systems that include power-electronic subsystems. Increases in simulation speed of 183-281% over established single-rate integration algorithms are demonstrated.

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Pulse Regulation Control Technique For Flyback Converter, Mehdi Ferdowsi, Ali Emadi Feb 2004

Pulse Regulation Control Technique For Flyback Converter, Mehdi Ferdowsi, Ali Emadi

Electrical and Computer Engineering Faculty Research & Creative Works

Pulse regulation, a fixed frequency control technique, is introduced and applied to flyback converter operating in discontinuous conduction mode (DCM). The control parameters are designed in a way that the converter operates as close as possible to the critical conduction mode. In contrast to the conventional pulse width modulation (PWM) control scheme, the principal idea of pulse regulation is to achieve output voltage regulation using high and low-power pulses. Pulse regulation is simple, cost effective, and enjoys a fast dynamic response. The proposed technique is applicable to any converter operating in DCM. However, this work mainly focuses on flyback topology. …

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A Multi-Processor Control System Architecture For A Cascaded Statcom With Energy Storage, Chang Qian, Stan Atcitty, Mariesa Crow Feb 2004

A Multi-Processor Control System Architecture For A Cascaded Statcom With Energy Storage, Chang Qian, Stan Atcitty, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents a multi-processor control system for a general purpose five-level cascaded inverter for real time power system applications. Practical design considerations for the digital controller architecture as well as the power converter are discussed and a 3 kVA laboratory prototype is presented. As a case study, a StatCom with battery energy storage was implemented on this multi-processor controlled inverter system. To eliminate the troublesome PI parameter tuning and the limitation of small signal models, which exist in conventional control for StatComs, a new and simple control method based on large signal model was designed to realize four-quadrant power …

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A Reconfigurable Facts System For University Laboratories, Liangying Dong, Zhiping Yang, Shen Chen, Lin Zhang, Stan Atcitty, Mariesa Crow Feb 2004

A Reconfigurable Facts System For University Laboratories, Liangying Dong, Zhiping Yang, Shen Chen, Lin Zhang, Stan Atcitty, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

To fully understand the dynamic performance of the multiple flexible ac transmission systems (FACTS) devices, a hardware setup is needed to complement software simulation for university research laboratories. This paper presents the schematic and basic controls of a reconfigurable FACTS system that can be used to realize the major voltage-sourced-converter FACTS topologies: the StatCom, the static synchronous series compensator (SSSC), and the unified power-flow controller (UPFC). Furthermore, the state models and control algorithms for the FACTS devices are proposed. The digital signal processor (DSP)-based control system enables new control methods to be rapidly implemented. The comparison of the experimental and …

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Low-Frequency Fast Inhomogeneous Plane-Wave Algorithm (Lf-Fipwa), L. (Lijun) J. Jiang, W. C. Chew Jan 2004

Low-Frequency Fast Inhomogeneous Plane-Wave Algorithm (Lf-Fipwa), L. (Lijun) J. Jiang, W. C. Chew

Electrical and Computer Engineering Faculty Research & Creative Works

A new method, the low-frequency fast inhomogeneous plane-wave algorithm (LF-FIPWA) is presented to extend the traditional multilevel fast multipole algorithm (MLFMA) and fast inhomogeneous plane-wave algorithm (FIPWA) seamlessly into the low-frequency range. It uses evanescent-wave extrapolation and translation techniques to overcome the low-frequency breakdown problem. The accuracy can be well controlled over a broad frequency range. Numerical examples show the effectiveness of this new algorithm.

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Flexural Strengthening Of Bridge Piers Using Frp Composites, Tarek Alkhrdaji, Antonio Nanni Jan 2004

Flexural Strengthening Of Bridge Piers Using Frp Composites, Tarek Alkhrdaji, Antonio Nanni

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The effectiveness of FRP jackets for increasing the shear capacity and the flexural ductility of reinforced concrete (RC) columns was demonstrated in many studies. However, for smaller axial loads, the contribution of FRP jackets to flexural strength is minimal. using FRP sheets in the direction of a column with end anchorage to improve its flexural capacity at the base is not easily achieved. This paper reports on a research project aimed at upgrading the flexural capacity of RC piers using near-surface mounted (NSM) FRP rods. Flexural strengthening and testing to failure of the piers were carried out on a bridge …

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Accuracy And Interferences For Enzyme-Linked Immunoassay Tests For Atrazine, Craig D. Adams, Hua Jiang, Michael Mcguire, Nicole Graziano, Alan Roberson, Michelle Frey Jan 2004

Accuracy And Interferences For Enzyme-Linked Immunoassay Tests For Atrazine, Craig D. Adams, Hua Jiang, Michael Mcguire, Nicole Graziano, Alan Roberson, Michelle Frey

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Atrazine is one of the most commonly used herbicides in the United States, therefore it is a regulatory concern and is extensively monitored in the environment, especially in drinking water. Because of the higher costs of gas chromatography (GC) methods, utility managers and regulators are considering the increased use of enzyme-linked immunosorbent assay (ELISA) methods for monitoring atrazine. an ELISA test kit was recently approved by the US Environmental Protection Agency. the research in this article points out potential biases and inaccuracies that may occur with such test kits. ELISA test kits for atrazine are typically precise (repeatable) but often …

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Method Of Creating Ultra-Fine Particles Of Materials Using A High-Pressure Mill, Marian Mazurkiewicz, B. E. Conrad Jan 2004

Method Of Creating Ultra-Fine Particles Of Materials Using A High-Pressure Mill, Marian Mazurkiewicz, B. E. Conrad

Mining Engineering Faculty Research & Creative Works

A method for creating ultra-fine particles of material using a high-pressure mill is described. The method includes placing a material in a first chamber and subjecting the material to a high-pressure fluid jet to divide it into particles. These particles are then transferred to a second chamber in which they are subjected to cavitation to further divide the particles into relatively smaller particles. These relatively smaller particles are then transferred to a third chamber, in which the particles collide with a collider to still further divide them into ultra-fine particles of the material. The mill of the present invention includes …

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Compact High-Voltage Generator Of Primary Power Based On Shock Wave Depolarization Of Lead Zirconate Titanate Piezoelectric Ceramics, Sergey I. Shkuratov, Evgueni F. Talantsev, Latika Menon, Henryk Temkin, Jason Baird, Larry L. Altgilbers Jan 2004

Compact High-Voltage Generator Of Primary Power Based On Shock Wave Depolarization Of Lead Zirconate Titanate Piezoelectric Ceramics, Sergey I. Shkuratov, Evgueni F. Talantsev, Latika Menon, Henryk Temkin, Jason Baird, Larry L. Altgilbers

Mining Engineering Faculty Research & Creative Works

The design and performance of a compact explosive-driven high-voltage primary power generator is presented. The generator utilizes a fundamental physical effect—depolarization of ferroelectric materials under longitudinal shock wave impact, when the shock wave is initiated along the polarization vector P. These primary power sources, containing energy-carrying elements made of lead zirconate titanate poled piezoelectric ceramics, with the volume from 0.35 to 3.3 cm3, are capable of producing pulses of high voltage with amplitudes up to 21.4 kV. The amplitude and full width at half-maximum of the high-voltage pulses are directly proportional to the thickness of the energy-carrying element, with coefficients …

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Summary Report: Strength Of Single L-Headers, Roger A. Laboube Jan 2004

Summary Report: Strength Of Single L-Headers, Roger A. Laboube

American Iron and Steel Institute (AISI) Specifications, Standards, Manuals and Research Reports (1946 - present)

No abstract provided.

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Corrosion Of Galvanized Fasteners Used In Cold-Formed Steel Framing, American Iron And Steel Institute Jan 2004

Corrosion Of Galvanized Fasteners Used In Cold-Formed Steel Framing, American Iron And Steel Institute

CCFSS Library (1939 - present)

This research program investigated the potential for corrosion of galvanized fasteners used in cold-formed steel framing by exposing test samples to a variety of environmental conditions frequently found in Hawaii and elsewhere. The results of this research will aid in the evaluation of galvanized fasteners in various exposure conditions. Five field enclosures were constructed on the island of Oahu at coastal locations on both windward and leeward shores, and in the interior of the island. Each field enclosure represented various aspects of typical cold-formed steel construction and was equipped with a complete weather station. This report details the design, construction …

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Metal Transfer In Arc Welding, Hai-Lung Tsai, P.-C. Wang Jan 2004

Metal Transfer In Arc Welding, Hai-Lung Tsai, P.-C. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A double pulse welding current method is disclosed for the generation and transfer of droplets of welding metal from an electrode wire to a workpiece in an arc welding process. A suitable background direct current level is specified to deliver a desired number of droplets to the weld site. During each cycle of droplet formation and transfer, a first increased current pulse is applied to the electrode and arc to generate a droplet on the tip of and electrode and then a second further increased current pulse is applied to timely separate the droplet from the electrode for transport in …

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Development And Implementation Of New Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan Jan 2004

Development And Implementation Of New Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A reconfigurable flight control method is developed to be implemented on an Unmanned Aircraft (UA), a thirty percent scale model of the Cessna 150. This paper presents the details of the UAV platform, system identification, reconfigurable controller design, development, and implementation on the UA to analyze the performance metrics. A Crossbow Inertial Measurement Unit provides the roll, pitch and yaw accelerations and rates along with the roll and pitch. The 100400 mini-air data boom from spaceage control provides the airspeed, altitude, angle of attack and the side slip angles. System identification is accomplished by commanding preprogrammed inputs to the control …

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Adjusting The Low Energy Threshold For Large Bodies In Pet, John W. Wilson, Timothy G. Turkington, James G. Colsher Jan 2004

Adjusting The Low Energy Threshold For Large Bodies In Pet, John W. Wilson, Timothy G. Turkington, James G. Colsher

Mining Engineering Faculty Research & Creative Works

The performance of a PET scanner on three different phantom sizes was studied as a function of low energy threshold (LET). Phantom cross sections ranged from 20 cm diameter circular to 28 cm x 43 cm oval and LET''s ranged from 350 keV to 475 keV, in 25 keV increments. System sensitivity, scatter fraction, and NEC were measured over a wide range of radioactivity levels. Increasing the low energy threshold lowered both sensitivity and scatter fraction. The statistical quality of the raw data was maximized for the 425 keV setting for all three phantoms. System stability and uniformity of response …

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Detection Of Basal Cell Carcinoma Using Electrical Impedance And Neural Networks, Rohit Dua, Daryl G. Beetner, William V. Stoecker, Donald C. Wunsch Jan 2004

Detection Of Basal Cell Carcinoma Using Electrical Impedance And Neural Networks, Rohit Dua, Daryl G. Beetner, William V. Stoecker, Donald C. Wunsch

Electrical and Computer Engineering Faculty Research & Creative Works

Variations in electrical impedance over frequency might be used to distinguish basal cell carcinoma (BCC) from benign skin lesions, although the patterns that separate the two are nonobvious. Artificial neural networks (ANNs) may be good pattern classifiers for this application. A preliminary study to show the potential of neural networks to distinguish benign from malignant skin lesions using electrical impedance is presented. Electrical impedance was measured in vivo from 1 kHz to 1 MHz at five virtual depths on 18 BCC and 16 benign or premalignant lesions. A feed-forward neural network was trained using back propagation to classify these lesions. …

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