Página 19 dos resultados de 100905 itens digitais encontrados em 0.129 segundos

‣ A low-power analog logarithmic map circuit with offset and temperature compensation for use in bionic ears

Sit, Ji-Jon, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 91 p.; 10351297 bytes; 10351034 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Ji-Jon Sit.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.; Includes bibliographical references (p. 74-75).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Architectural study of high-speed networks with optical bypassing

Saengudomlert, Poompat, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 158 p.; 1091738 bytes; 1091490 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
We study the routing and wavelength assignment (RWA) problem in wavelength division multiplexing (WDM) networks with no wavelength conversion. In a high-speed core network, the traffic can be separated into two components. The first is the aggregated traffic from a large number of small-rate users. Each individual session is not necessarily static but the combined traffic streams between each pair of access nodes are approximately static. We support this traffic by static provisioning of routes and wavelengths. In particular, we develop several off-line RWA algorithms which use the minimum number of wavelengths to provide I dedicated wavelength paths between each pair of access nodes for basic all-to-all connectivity. The topologies we consider are arbitrary tree, bidirectional ring, two-dimensional torus, and binary hypercube topologies. We observe that wavelength converters do not decrease the wavelength requirement to support this uniform all-to-all traffic. The second traffic component contains traffic sessions from a small number of large-rate users and cannot be well approximated as static due to insufficient aggregation. To support this traffic component, we perform dynamic provisioning of routes and wavelengths. Adopting a nonblocking formulation...

‣ Radiolocation using AM broadcast signals; Radiolocation using amplitude modulation broadcast signals

Hall, Timothy Douglas, 1970-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 294 p.; 10673563 bytes; 10673275 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
(cont.) Previous attempts at signal-of-opportunity navigation using carrier phase sidestepped the ambiguity problem by requiring that the initial position of the rover be known and that phase variations be tracked without interruption. I designed and implemented an ambiguity-function method that enables the phase ambiguity to be resolved instantaneously without position initialization or signal-tracking continuity. I encountered several impediments to AM-broadcast-based radiolocation that, if not dealt with appropriately, reduce positioning accuracy, reduce ambiguity-resolution robustness, or both. AM transmitter position uncertainty directly causes receiver position-determination uncertainty. Since the error in published antenna positions sometimes exceeds 100 meters, I conducted sub-meter-accuracy geodetic surveys of 29 Boston-area AM-broadcast antennas. The directional radiation patterns of the array antennas of many AM broadcast radio stations have phases that vary with azimuth angle. I developed and implemented a model for the phase of a directional antenna that nearly eliminated theerrors caused by this effect. AM broadcast signals travel primarily as groundwaves, which propagate with phase velocities that depend on the electrical properties of the ground. Using simulations and empirical data...

‣ The resolution enhancements of real-time captured images

Cheng, Christopher J. (Christopher John), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 89 leaves; 2895932 bytes; 2895683 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Christopher J. Cheng.; Thesis (M.Eng. and S.B.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.; Includes bibliographical references (leaves 77-78).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Providing quality of service over high speed electronic and optical switches

Koksal, Can Emre, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 239 leaves; 1410233 bytes; 1410161 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
In a network, multiple links are interconnected by means of switches. A switch is a device with multiple input and output links, and its job is to move data from the input links to the output links. In this thesis, we focus on a number of fundamental issues concerning the quality of service provided by electronic and optical switches. We discuss various mechanisms that enable the support of quality of service requirements. In particular, we explore fundamental limitations of current high speed packet switches and develop new techniques and architectures that make possible the provision of certain service guarantees. We then study optical wavelength switches and illustrate how similar ideas can be applied in a manner consistent with the current state of optical switching technology. First, we focus on providing rate guarantees over packet switches. We develop a method called rate quantization which converts the set of desired rates into a certain discrete set such that the quality of service guarantees can be greatly improved with a small resource speedup. Moreover, quantization simplifies rate provisioning for dynamically changing traffic demands since it allows service opportunities for different input output link pairs to be scheduled with minimal dependence. We illustrate an isomorphism between packet switch schedulers and Clos networks to develop such schedulers.; (cont.) Next...

‣ A hierarchical framework for constructing computationally efficient algorithms for distributed inference problems

Chu, Maurice Kyojin, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 391 p.; 5703982 bytes; 5733665 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
In this thesis, we present a methodology for designing computationally efficient algorithms for large-scale inference systems on system architectures with distributed autonomous agents. The principle of information-based computation is the underlying idea driving elements of this methodology. The methodology consists of a layered information processing architecture, which organizes specific inference tasks into layers so that the information extracted from these tasks can be exploited to design an efficient inference system, and the hierarchy, which is a representation combining elements of circuits and branching programs from which efficient distributed local algorithms implementing global tasks on general system architectures can be generated. The general issues addressed by this methodology are: (1) how to efficiently collect distributed information for estimation when collecting information is expensive, (2) how to distribute a global algorithm among multiple agents, and (3) how to take advantage of prior computations to aid in subsequent computations. To demonstrate that the methodology is a good one, we present an application of sensor networks to battlefield awareness. The problem is to gain intelligence about targets in the environment from the information collected by a set of sensor nodes which are distributed over a field and have real physical constraints on energy and communication. In particular...

‣ Graph spectra and modal dynamics of oscillatory networks

Ayazifar, Babak, 1967-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 191 leaves; 1004633 bytes; 1004415 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
Our research focuses on developing design-oriented analytical tools that enable us to better understand how a network comprising dynamic and static elements behaves when it is set in oscillatory motion, and how the interconnection topology relates to the spectral properties of the system. Such oscillatory networks are ubiquitous, extending from miniature electronic circuits to large-scale power networks. We tap into the rich mathematical literature on graph spectra, and develop theoretical extensions applicable to networks containing nodes that have finite nonnegative weights-including nodes of zero weight, which occur naturally in the context of power networks. We develop new spectral graph-theoretic results spawned by our engineering interests, including generalizations (to node-weighted graphs) of various structure-based eigenvalue bounds. The central results of this thesis concern the phenomenon of dynamic coherency, in which clusters of vertices move in unison relative to each other. Our research exposes the relation between coherency and network structure and parameters. We study both approximate and exact dynamic coherency. Our new understanding of coherency leads to a number of results. We expose a conceptual link between theoretical coherency and the confinement of an oscillatory mode to a node cluster. We show how the eigenvalues of a coherent graph relate to those of its constituent clusters.; (cont.) We use our eigenvalue expressions to devise a novel graph design algorithm; given a set of vertices (of finite positive weight) and a desired set of eigenvalues...

‣ Ferrofluid flow phenomena

Franklin, Thomas A. (Thomas Andrew), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 158 leaves; 2810982 bytes; 2591785 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Thomas A. Franklin.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (leaves 155-158).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Estimation of GMRFs by recursive cavity modeling; Estimation of Gauss-Markov random fields by recursive cavity modeling

Johnson, Jason K. (Jason Kyle)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 205 p.; 2160717 bytes; 2160449 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Jason J. Johnson.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 199-205).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Plan-based proactive computing

Look, Gary Wai Keung, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 88 leaves; 1414652 bytes; 1401403 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Gary Wail Keung Look.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (leaves 81-88).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Robustness in large-scale random networks

Kim, Minkyu, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 76 p.; 454323 bytes; 454136 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Minkyu Kim.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 73-76).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Demonstration system for a low-power seismic detector and classifier

Ranger, Elliot Richard, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 230 p.; 8977315 bytes; 8976939 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Elliot Richard Ranger.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 229-230).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Reconfiguration of a value function-based guidance system

Valenti, Mario J. (Mario James), 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 111 leaves; 7355208 bytes; 7354999 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Mario J. Valenti.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (leaves 109-111).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ High-reliability architectures for networks under stress

Weichenberg, Guy E. (Guy Elli), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 165 p.; 900761 bytes; 900510 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Guy E. Weichenberg.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 157-165).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Corpus-based unit selection for natural-sounding speech synthesis

Yi, Jon Rong-Wei, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 214 p.; 3462128 bytes; 3461885 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
Speech synthesis is an automatic encoding process carried out by machine through which symbols conveying linguistic information are converted into an acoustic waveform. In the past decade or so, a recent trend toward a non-parametric, corpus-based approach has focused on using real human speech as source material for producing novel natural-sounding speech. This work proposes a communication-theoretic formulation in which unit selection is a noisy channel through which an input sequence of symbols passes and an output sequence, possibly corrupted due to the coverage limits of the corpus, emerges. The penalty of approximation is quantified by substitution and concatenation costs which grade what unit contexts are interchangeable and where concatenations are not perceivable. These costs are semi-automatically derived from data and are found to agree with acoustic-phonetic knowledge. The implementation is based on a finite-state transducer (FST) representation that has been successfully used in speech and language processing applications including speech recognition. A proposed constraint kernel topology connects all units in the corpus with associated substitution and concatenation costs and enables an efficient Viterbi search that operates with low latency and scales to large corpora. An A* search can be applied in a second...

‣ Structure of the polar electrojet antenna

Riddolls, Ryan James, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 156 p.; 2163527 bytes; 2173466 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
Field experiments were performed in Gakona, Alaska in August and November 2002. The ionospheric conductivity was periodically perturbed using amplitude-modulated radiation from the HAARP HF transmitter (1 MW power, 14 dB gain, 3.3-5.8 MHz carrier, 0.1-40 kHz modulation). The conductivity perturbations lead to perturbations to the natural flow of electrojet current in the lower ionosphere, resulting in ELF/VLF radiation at the modulation frequency. Measurements of the radiation, along with analytic and numerical models, suggest that a vertical loop with a scale size of 10 km is the dominant current structure excited during the experiments.; by Ryan James Riddolls.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 153-156).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ A superconducting bandpass delta-sigma modulator for direct analog-to-digital conversion of microwave radio

Bulzacchelli, John F. (John Francis)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 305 p.; 3483085 bytes; 3482840 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
Direct analog-to-digital conversion of multi-GHz radio frequency (RF) signals is the ultimate goal in software radio receiver design but remains a daunting challenge for any technology. This thesis examines the potential of superconducting technology for realizing RF analog-to-digital converters (ADCs) with improved performance. A bandpass delta-sigma (AE) modulator is an attractive architecture for digitizing narrowband signals with high linearity and a large signal-to-noise ratio (SNR). The design of a superconducting bandpass AE modulator presented here exploits several advantages of superconducting electronics: the high quality factor of resonators, the high sampling rates of comparators realized with Josephson junctions, natural quantization of voltage pulses, and high circuit sensitivity. Demonstration of a superconducting circuit operating at clock rates in the tens of GHz is often hindered by the difficulty of high speed interfacing with room-temperature test equipment. In this work, a test chip with integrated acquisition memory is used to simplify high speed testing in a cryogenic environment. The small size (256 bits) of the on-chip memory severely limits the frequency resolution of spectra based on standard fast Fourier transforms. Higher resolution spectra are obtained by "segmented correlation"...

‣ Segmentation and alignment of speech and sketching in a design environment

Adler, Aaron D. (Aaron Daniel), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 205 p.; 2440992 bytes; 2440646 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Aaron D. Adler.; Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 203-205).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ An API for location aware computing; Application Programming Interface for location aware computing

Bell, Jason Murray, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 90 p.; 1142248 bytes; 1141965 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Jason Murray Bell.; Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 89-90).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Experimental study of the frequency correlation of space-time entangled photons

Dauler, Eric A. (Eric Anthony), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 58 leaves; 409684 bytes; 433002 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
66.504053%
by Eric A. Dauler.; Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (leaves 57-58).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.