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Articles 1 - 9 of 9
Full-Text Articles in Engineering
Quantum Dot Infrared Photodetector Fabricated By Pulsed Laser Deposition Technique, Mohammed Hegazy, Tamer Refaat, Nurul Abedin, Hani Elsayed-Ali
Quantum Dot Infrared Photodetector Fabricated By Pulsed Laser Deposition Technique, Mohammed Hegazy, Tamer Refaat, Nurul Abedin, Hani Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
Pulsed laser deposition is used to fabricate multilayered Ge quantum-dot photodetector on Si(100). Growth was studied by reflection high-energy electron diffraction and atomic force microscopy. The difference in the current values in dark and illumination conditions was used to measure the device sensitivity to radiation. Spectral responsivity measurements reveal a peak around 2 μm, with responsity that increases three orders of magnitude as bias increases from 0.5 to 3.5 V.
Growth Of Ge Quantum Dots On Si(100)-(2×1) By Pulsed Laser Deposition, M. S. Hegazy, H. E. Elsayed-Ali
Growth Of Ge Quantum Dots On Si(100)-(2×1) By Pulsed Laser Deposition, M. S. Hegazy, H. E. Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
Self-assembled germanium quantum dots (QDs) were grown on Si(100)-(2×1) by pulsed laser deposition. In situ reflection-high energy electron diffraction (RHEED) and postdeposition atomic force microscopy are used to study the growth of the QDs. Several films of different thicknesses were grown at a substrate temperature of 400 °C using a Q-switched Nd:yttrium aluminum garnet laser (λ= 1064 nm, 40 ns pulse width, 23 J/cm 2 fluence, and 10 Hz repetition rate). At low film thicknesses, hut clusters that are faceted by different planes, depending on their height, are observed after the completion of the wetting layer. With increasing film thickness, …
Wavelet Analysis In Virtual Colonoscopy, Sharon Greenblum, Jiang Li, Adam Huang, Ronald M. Summers, Armando Manduca (Ed.), Amir A. Amini (Ed.)
Wavelet Analysis In Virtual Colonoscopy, Sharon Greenblum, Jiang Li, Adam Huang, Ronald M. Summers, Armando Manduca (Ed.), Amir A. Amini (Ed.)
Electrical & Computer Engineering Faculty Publications
The computed tomographic colonography (CTC) computer aided detection (CAD) program is a new method in development to detect colon polyps in virtual colonoscopy. While high sensitivity is consistently achieved, additional features are desired to increase specificity. In this paper, a wavelet analysis was applied to CTCCAD outputs in an attempt to filter out false positive detections. 52 CTCCAD detection images were obtained using a screen capture application. 26 of these images were real polyps, confirmed by optical colonoscopy and 26 were false positive detections. A discrete wavelet transform of each image was computed with the MATLAB wavelet toolbox using the …
Electron Bernstein Wave Simulations And Comparison To Preliminary Nstx Emission Data, Josef Preinhaelter, Jakub Urban, Pavol Pavlo, Gary Taylor, Steffi Diem, Linda L. Vahala, George Vahala
Electron Bernstein Wave Simulations And Comparison To Preliminary Nstx Emission Data, Josef Preinhaelter, Jakub Urban, Pavol Pavlo, Gary Taylor, Steffi Diem, Linda L. Vahala, George Vahala
Electrical & Computer Engineering Faculty Publications
Simulations indicate that during flattop current discharges the optimal angles for the aiming of the National Spherical Torus Experiment (NSTX) antennae are quite rugged and basically independent of time. The time development of electron Bernstein wave emission (EBWE) at particular frequencies as well as the frequency spectrum of EBWE as would be seen by the recently installed NSTX antennae are computed. The simulation of EBWE at low frequencies (e.g., 16 GHz) agrees well with the recent preliminary EBWE measurements on NSTX. At high frequencies, the sensitivity of EBWE to magnetic field variations is understood by considering the Doppler broadened electron …
Hybrid Committee Classifier For A Computerized Colonic Polyp Detection System, Jiang Li, Jianhua Yao, Nicholas Petrick, Ronald M. Summers, Amy K. Hara, Joseph M. Reinhardt (Ed.), Josien P.W. Pluim (Ed.)
Hybrid Committee Classifier For A Computerized Colonic Polyp Detection System, Jiang Li, Jianhua Yao, Nicholas Petrick, Ronald M. Summers, Amy K. Hara, Joseph M. Reinhardt (Ed.), Josien P.W. Pluim (Ed.)
Electrical & Computer Engineering Faculty Publications
We present a hybrid committee classifier for computer-aided detection (CAD) of colonic polyps in CT colonography (CTC). The classifier involved an ensemble of support vector machines (SVM) and neural networks (NN) for classification, a progressive search algorithm for selecting a set of features used by the SVMs and a floating search algorithm for selecting features used by the NNs. A total of 102 quantitative features were calculated for each polyp candidate found by a prototype CAD system. 3 features were selected for each of 7 SVM classifiers which were then combined to form a committee of SVMs classifier. Similarly, features …
Melting And Solidification Study Of As-Deposited And Recrystallized Bi Thin Films, M. K. Zayed, H. E. Elsayed-Ali
Melting And Solidification Study Of As-Deposited And Recrystallized Bi Thin Films, M. K. Zayed, H. E. Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
Melting and solidification of as-deposited and recrystallized Bi crystallites, deposited on highly oriented 002-graphite at 423 K, were studied using reflection high-energy electron diffraction (RHEED). Films with mean thickness between 1.5 and 33 ML (monolayers) were studied. Ex situ atomic force microscopy was used to study the morphology and the size distribution of the formed nanocrystals. The as-deposited films grew in the form of three-dimensional crystallites with different shapes and sizes, while those recrystallized from the melt were formed in nearly similar shapes but different sizes. The change in the RHEED pattern with temperature was used to probe the melting …
A Fast Parallelized Computational Approach Based On Sparse Lu Factorization For Predictions Of Spatial And Time-Dependent Currents And Voltages In Full-Body Biomodels, Ashutosh Mishra, Ravindra P. Joshi, Karl H. Schoenbach, C. D. Clark Iii
A Fast Parallelized Computational Approach Based On Sparse Lu Factorization For Predictions Of Spatial And Time-Dependent Currents And Voltages In Full-Body Biomodels, Ashutosh Mishra, Ravindra P. Joshi, Karl H. Schoenbach, C. D. Clark Iii
Electrical & Computer Engineering Faculty Publications
Realistic and accurate numerical simulations of electrostimulation of tissues and full-body biomodels have been developed and implemented. Typically, whole-body systems are very complex and consist of a multitude of tissues, organs, and subcomponents with diverse properties. From an electrical standpoint, these can be characterized in terms of separate conductivities and permittivities. Accuracy demands good spatial resolution; thus, the overall tissue/animal models need to be discretized into a fine-grained mesh. This can lead to a large number of grid points (especially for a three-dimensional entity) and can place prohibitive requirements of memory storage and execution times on computing machines. Here, the …
Dynamics Of An Atmospheric Pressure Plasma Plume Generated By Submicrosecond Voltage Pulses, Xinpei Lu, Mounir Laroussi
Dynamics Of An Atmospheric Pressure Plasma Plume Generated By Submicrosecond Voltage Pulses, Xinpei Lu, Mounir Laroussi
Electrical & Computer Engineering Faculty Publications
Nonequilibrium plasmas driven by submicrosecond high voltage pulses have been proven to produce high-energy electrons, which in turn lead to enhanced ionization and excitations. Here, we describe a device capable of launching a cold plasma plume in the surrounding air. This device, "the plasma pencil," is driven by few hundred nanosecond wide pulses at repetition rates of a few kilohertz. Correlation between current-voltage characteristics and fast photography shows that the plasma plume is in fact a small bulletlike volume of plasma traveling at unusually high velocities. A model based on photoionization is used to explain the propagation kinetics of the …
Femtosecond Pulsed Laser Deposition Of Indium On Si (100), Mohamed A. Hafez, Hani E. Elsayed-Ali
Femtosecond Pulsed Laser Deposition Of Indium On Si (100), Mohamed A. Hafez, Hani E. Elsayed-Ali
Electrical & Computer Engineering Faculty Publications
Deposition of indium on Si(100) substrates is performed under ultrahigh vacuum with an amplified Ti:sapphire laser (130 fs) at wavelength of 800 nm and laser fluence of 0.5 J/cm2. Indium films are grown at room temperature and at higher substrate temperatures with a deposition rate of similar to 0.05 ML/pulse. Reflection high-energy electron diffraction (RHEED) is used during the deposition to study the growth dynamics and the surface structure of the grown films. The morphology of the grown films is examined by ex situ atomic force microscopy (AFM). At room temperature indium is found to form epitaxial two-dimensional …