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Entropy rate estimators and their application to blind source separation
No full textThe characterization of a signal is one of the key issues in statistical signal processing and is vital to the success of many methods. Thus, the goal of characterization techniques is to achieve a desirable balance between flexibility and maintaining a simple form, so as to allow for generalization and efficient implementation. In this dissertation, we propose a new density estimation technique, which uses the principle of maximum entropy with Gaussian kernels. By jointly using global and local measuring functions, the new density estimation method enjoys a high level of flexibility while providing a simple parametric form for the estimated density function. When considering a signal with sample dependence, the signal cannot be fully characterized by its density function. To address this issue, we propose the use of entropy rate to provide a powerful tool for data analysis, since it accounts for all types of diversity: higher-order statistics, sample dependence, noncircularity for a complex-valued process, and dependence across processes for a vector-valued process. We propose entropy rate estimators for real-valued processes based on both Markovian and invertible source models. We extend the entropy rate estimator to complex-valued and vector-valued processes by using a widely linear whitening filter and vector autoregressive model, respectively. The new entropy rate estimators are shown to exploit all these statistical properties effectively. These entropy rate estimators can be used in a wide array of applications in statistical signal processing. In this work, we mainly focus on: model order selection, real-valued independent component analysis, complex-valued independent component analysis, and independent vector analysis. Detecting the number of latent signals in a given number of observations, or order detection, is a key issue in many signal processing problems. Many of the commonly used methods to solve this problem are based on information theoretic criteria. In order to facilitate the use of information theoretic criteria, these approaches address the issue of dependent samples by downsampling the dataset. However, downsampling the data decreases the sample size, which can cause degradation in the accuracy of the order estimation. Using an entropy rate estimator, we write the likelihood based on the entire data set and use it in an information theoretic framework. We propose two entropy-rate-based order estimation methods and show the performance improvement they offer with examples. In addition, the consistency of the entropy-rate-based methods is shown when the sample size goes to infinity. By assuming latent sources are statistically independent, independent component analysis separates underlying sources from a given linear mixture. Since in many applications, latent sources are both non-Gaussian and have sample dependence, it is desirable to exploit both properties jointly. In this work, we propose to use the mutual information rate to construct a general framework for analysis and derivation of algorithms that account for both types of diversity. We introduce four algorithms for the problem of independent component analysis, and show that their performance can approach the Cramer-Rao lower bound. Complex-valued signals frequently arise in applications such as communications, radar, and biomedicine, as well as processing when real-valued signals are in a transform domain. Independent component analysis, when implemented in the complex domain, enjoys the addition of yet another type of diversity, noncircularity of the sources---underlying components. Using the new entropy rate estimator, we develop a new complex-valued independent component analysis algorithm, which exploits all three types of diversity, non-Gaussianity, sample dependence, and noncircularity. In addition, we establish the general form of the Fisher information matrix and Cramer-Rao lower bound and show the identification conditions for the complex-valued independent component analysis problem. Experimental results show that the new method accounts for all three types of diversity effectively and provides desirable performance for a wide variety of sources. Additionally, the entropy rate estimator for vector-valued processes is used for the independent vector analysis problem, which is a generalization of independent component analysis to multiple datasets and adds the use of one more diversity, the dependence across multiple datasets. Using mutual information rate, we propose a new method that takes all these types of diversity into account
Surface Reactions During the Atomic Layer Deposition of High-κ Dielectrics on III-V Semiconductor Surfaces
No full textThe quality of the dielectric/semiconductor interface is one of the most critical parameters for the fabrication of high-speed and low-power-consumption III-V semiconductor based metal-oxide-semiconductor field effect transistors (MOSFETs), as it determines the device performance. This dissertation contains investigations of the deposition and interface of binary oxide films on GaAs(100) and InAs(100) surfaces aiming at understanding the removal of the surface native oxides during certain atomic layer deposition (ALD) processes. To accomplish that, two complementary experimental approaches have been used. Initially, films were deposited in a conventional ALD reactor and characterized ex situ using spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The systems examined were Ta2O5 on GaAs(100) surfaces from pentakis(dimethylamino) tantalum (Ta(N(CH3)2)5, PDMAT) and TiO2 on GaAs(100) and InAs(100) surfaces from tetrakis(dimethylamino) titanium (Ti(N(CH3)2)4, TDMAT). For these systems, deposition at the optimal ALD temperature resulted in practically sharp interfaces. Indium oxides were found to diffuse through ~ 6 nm of TiO2 film and accumulate on the topmost film layer. For the ALD of Ta2O5 on GaAs(100) surfaces, native oxide removal was enhanced at deposition temperatures above the ALD window; for ALD of TiO2 on both GaAs(100) and InAs(100) surfaces, native oxide removal was enhanced as the deposition temperatures increased up to 250 �C, while oxidation of the interface was observed for deposition above 300 �C due to the formation of noncontinuous films. To elucidate the surface reactions occurring during the deposition, an in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy apparatus was constructed and used to investigate the surface reactions during the ALD of TiO2 and HfO2 on GaAs(100) surfaces. The existence of a ligand exchange mechanism was verified for both processes. Additionally, the formation of methylmethyleneimine (CH3N=CH2, MMI) was observed, indicating the existence of a beta hydride reaction pathway. Additionally, at 275 �C continuous removal of arsenic oxides was observed during the first 20 process cycles, an observation that challenges the prevailing understanding of the native oxide removal and indicates a much more complex surface chemistry
Untitled [Wooden wardrobe]
No full textAdam_Neese__Fort_Worth__TX__Adjunct_Professor__The_University_of_North_Texas_February_22__2014_at_0915AMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Water Street Remix
No full textChris_Peregoy_UMBC_Water_Street_Remix_February_08__2014_at_0431PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Untitled [Hanging lights and ballerina over city skyline]
No full textDaniel_Cannistra_UMBC_February_22__2014_at_0811PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Our Lady of Perceptual Revolution
No full textGarin_Horner_Adrian_College__Adrian__Michigan_Our_Lady_of_Perceptual_Revolution_February_24__2014_at_0219PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Bagpipers Nightmare
No full textHenry_Aragoncillo__Bagpipers_Nightmare_March_31__2014_at_0728PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Untitled [Legs wearing boots holding up sink]
No full textJenna_Stebbins_January_14__2014_at_1001PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Baltimore Blue Light Special Broadway Recreational Pier now defunct
No full textJohn_Deamond__Montgomery_College__Instructional_Lab_Coordinator__Baltimore_Blue_Light_Special_Broadway_Recreational_Pier__now_defunct__February_22__2014_at_0723PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe
Untitled [Cow head]
No full textJosie_Ingate_February_22__2014_at_0531PMThese images were created as part of the Hughes Remix project, a collaborative endeavor developed by UMBC's Albin O. Kuhn Library Special Collections and the Department of Visual Art to foster creative engagement with archival holdings in conjunction with the 2014 Society for Photographic Education annual conference. UMBC's Special Collections offered a selection of images from the Hughes Company Glass Negatives (http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughes) collection for SPE members and conference attendees to remix, reinvent, reinterpret, and reimagine the images in this collection of Baltimore street scenes, promotional and advertising photographs, businesses, churches, schools, monuments, factories, machinery, and portraits. Images that were created were displayed during the conference as well as on a Tumblr site and are now archived in the Special Collections. Full details of the project can be found at: http://hughes-remix.tumblr.com/overview.The original Hughes Company Glass Negatives collection can be found at: http://contentdm.ad.umbc.edu/cdm/landingpage/collection/hughe