Página 5 dos resultados de 10730 itens digitais encontrados em 0.062 segundos

Using hyperbolic tangents in integer factoring

Pinter, Ron Y
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 45 leaves; 5137272 bytes; 5137031 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Ron Yair Pinter.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Bibliography: leaf 45.

Automotive engine control : a linear quadratic approach

Lewis, James Brian
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 211 [i.e. 212] leaves; 16125405 bytes; 16125164 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by James Brian Lewis.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

Stochastic optimization for discrete-time systems

Lauer, Gregory S
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 161 leaves; 9263100 bytes; 9262857 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Gregory S. Lauer.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 157-161.

Filtering for bilinear systems

Vallot, Lawrence Charles
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 88 leaves; 3389151 bytes; 3388909 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Lawrence Charles Vallot.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

Minimum-variance tracking of pseudo-random number codes

Cartelli, John A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 179 leaves; 13432642 bytes; 13432402 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by John A. Cartelli.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

Decoding and control procedures for partially observable Markov processes

Amram, Joseph A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 103 leaves; 5005223 bytes; 5004982 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Joseph A. Amram.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographical references.

Reconstruction from projections based on detection and estimation of objects

Rossi, David John
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 341 leaves; 14320922 bytes; 14320678 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by David John Rossi.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaves 336-341.

A primer on partially observable Markov processes

Amram, Joseph A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 69 leaves; 3521045 bytes; 3520803 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Joseph A. Amram.; Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Includes bibliographical references.

An integrated optics pulse shaping device

Shepard, Scott Roger
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: [1], 128 leaves; 7014899 bytes; 7014656 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Scott Roger Shepard.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Includes bibliographical references.

An investigation into the coding of halftone pictures

Chao, Yao-Ming
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 174 leaves; 14129599 bytes; 14129356 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
by Yao-Ming Chao.; Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1982.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING; Bibliography: leaves 166-174.

Integrated optical filters using Bragg gratings and resonators

Khan, Mohammad Jalal
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 213 p.; 16492170 bytes; 16491925 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
This thesis provides an in-depth study of optical filters made using integrated Bragg gratings and Bragg resonators. Various topologies for making add/drop filters using integrated gratings are outlined. Each class of devices is studied in detail and the theoretical tools needed for designing the add/drop are developed. First-order filters using Bragg resonators do not meet WDM add/drop filter specifications. Consequently, schemes to design higher-order filters are derived. The relative advantages and disadvantages of the various possiblities are outlined. Preliminary integrated Bragg grating devices, in InP, were designed using the tools developed. The fabricated devices were measured. The measurements revealed low-loss structures with a < 0.1 cm-l and high-Q Bragg resonators with Q > 40, 000. Measurements on higher-order inline coupled Bragg resonator filters showed flat-top and fast roll-offs. The results of the measurements and comparison with the theory are presented for the various devices. The results reveal that Bragg grating based devices offer tremendous potential for use as add/drop filters in WDM systems.; by Mohammad Jalal Khan.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science...

A low-power reconfigurable analog-to-digital converter

Gulati, Kush
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 200 p.; 15127453 bytes; 15127213 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
This thesis presents the concept, theory and design of a low power CMOS analog-to-digital converter that can digitize signals over a wide range of bandwidth and resolution with adaptive power consumption. The converter achieves the wide operating range by reconfiguring (1) its architecture between pipeline and delta-sigma modes (2) by varying its circuit parameters such as size of capacitors, length of pipeline, oversampling ratio, among others and (3) by varying the bias currents of the opamps in proportion with converter sampling frequency, accomplished through the use of a phase-locked loop. Target input signals for this ADC include high frequency and moderate resolution signals such as video and low I.F. in radio Receivers, low frequency and high resolution signals from seismic sensors and MEMs devices, and others that fall in between these extremes such as audio, voice and general purpose data-acquisition. This converter also incorporates several power reducing features such as thermal noise limited design, global converter chopping in the pipeline mode, opamp scaling, opamp sharing between consecutive stages in the pipeline mode, an opamp chopping technique in the delta-sigma mode, and other design techniques. The opamp chopping technique achieves faster closed-loop settling time and lower thermal noise than conventional design.; (cont.) At a converter power supply at 3.3V...

Decoupling congestion control and bandwidth allocation policy with application to high bandwidth-delay product networks

Katabi, Dina, 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 129 p.; 9557907 bytes; 9557665 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
In this dissertation, we propose a new architecture for Internet congestion control that decouples the control of congestion from the bandwidth allocation policy. We show that the new protocol, called XCP, enables very large per-flow throughput (e.g., more than 1 Gb/s), which is unachievable using current congestion control. Additionally, we show via extensive simulations that XCP significantly improves the overall performance, reducing drop rate by three orders of magnitude, increasing utilization, decreasing queuing delay, and attaining fairness in a few RTTs. Using tools from control theory, we model XCP and demonstrate that, in steady state, it is stable for any capacity, delay, and number of sources. XCP does not maintain any per-flow state in routers and requires only a few CPU cycles per packet making it implementable in high-speed routers. Its flexible architecture facilitates the design and implementation of quality of service, such as guaranteed and proportional bandwidth allocations. Finally, XCP is amenable to gradual deployment.; by Dina Katabi.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 124-129).

Passive components for dense optical integration based on high index-contrast

Manolatou, Christina
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 185 p.; 10164864 bytes; 10187953 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
This work presents a theoretical and numerical investigation of high index-contrast passive components that can serve as building blocks at the end-pointsand nodes of WDM communications systems. The main characteristic of these structures is their miniature size (on the order of the optical wavelength), and their low radiation loss due to the strong light confinement in high index-contrast systems. Thus large scale, high density optical integration may be possible with the associated advantages of increased functionality, compactness and low-cost. Novel devices for filtering, optical interconnections and coupling to fibers are presented, specifically: a class of resonant add/drop filters that rely on symmetry and degeneracy of modes, low-loss right-angle bends, splitters, crossings based on transmission cavities, and fiber-chip couplers based on cascades of resonators or lensing mechanisms. Their operating principles are explained and an approximate analysis is obtained by analytical methods such as coupled-mode theory and gaussian/ray optics. For accurate analysis and optimized design, extensive numerical simulations are performed using the Finite Difference Time Domain method. The numerical results are in good agreement with the experimental data obtained for bends that were farbricated and tested at MIT. Issues that remain to be addressed for this technology to be viable and possible future directions are also discussed.; by Christina Manolatou.; Thesis (Ph. D.)--Massachusetts Institute of Technology...

Design of a wideband, 100 W, 140 GHz gyroklystron amplifier

Joye, Colin D., 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 110 p.; 3398814 bytes; 3411983 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
The design study of a 140 GHz, 100 W continuous wave gyroklystron amplifier is presented. The device is intended for use in Dynamic Nuclear Polarization (DNP) enhanced Nuclear Magnetic Resonance (NMR) spectroscopy experiments. The gyroklystron has five cavities and operates in the TE(0,2) mode with a low power electron beam. The design was performed using MAGY, a nonlinear code for modelling gyrotron devices. The design process of the gyroklystron starting from the linear theory to the optimization of the final design in MAGY has been described in detail. Stagger tuning was employed to broadband the device. The design yields 130 W peak power, 36 dB saturated gain, and a -3 dB bandwidth of over 1 GHz (0.75%) with a 15 kV, 150 mA electron beam having a beam pitch factor of 1.5, radius of 0.64 mm and calculated perpendicular momentum spread of 4%. Preliminary designs of the Magnetron Inject Gun (MIG), the input and output couplers, and the mode converter to transform the TE(0,2) operating mode to the HE(1,1) mode for low loss transmission of the output power are also presented. The design meets the specifications for the DNP experiment.; by Colin D. Joye.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science...

A one-round algorithm for virtually synchronous group communication in wide area networks

Khazan, Roger Igor
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 165 p.; 8163207 bytes; 8163016 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
Group communication services, and especially those that implement Virtual Synchrony semantics, are powerful middleware systems that facilitate the development of fault-tolerant distributed applications. In this thesis, we present a high quality, theoretical design of a group communication service that implements Virtual Synchrony semantics and is aimed for deployment in wide-area networks (WANs). The design features a novel algorithm for implementing Virtual Synchrony semantics; the algorithm is more appropriate for WANs than the existing solutions because it involves fewer rounds of communication and operates in a scalable WAN-oriented architecture. The high quality of the design refers to the level of formality and rigor at which it is done: The design includes formal and precise specifications, algorithms, correctness proofs, and performance analyses. We develop the necessary supporting theory and methodology required for producing and evaluating this design. In particular, we develop a formal, inheritance-based, methodology that supports incremental construction of specifications, models, and proofs. This methodology helps us manage the complexity of the design and makes it evident which part of the algorithm implements which property of the system. We also develop new...

Experimental study of a 1.5-MW, 110-GHz gyrotron oscillator

Anderson, James P. (James Paul), 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 171 p.; 9183134 bytes; 9204450 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
This thesis reports the design, construction and testing of a 1.5 MW, 110 GHz gyrotron oscillator. This high power microwave tube has been proposed as the next evolutionary step for gyrotrons used to provide electron cyclotron heating required in fusion devices. A short pulse gyrotron based on the industrial tube design was built at MIT for experimental studies. The experiments are the first demonstration of such high powers at 110 GHz. Using a 96 kV, 40 A electron beam, over 1.4 MW was axially extracted in the design (TE22,6) mode in 3 us pulses, corresponding to a microwave efficiency of 37 %. The beam alpha, the ratio of transverse to axial velocity in the electron beam, was measured with a probe. At the high efficiency operating point the beam alpha was measured as 1.33. This value of alpha is less than the design value of 1.4, possibly accounting for the slightly reduced experimental efficiency. The output power and efficiency, as a function of magnetic field, beam voltage, and beam current, are in good agreement with nonlinear theory and simulations with the MAGY code. In another phase of the experiment, a second tube was built and tested. This tube used the same gun and cavity but also incorporated an internal mode converter to transform the generated waveguide mode into a free-space propagating beam. The gun was tested to full power and current in the experiment. Preliminary results were obtained. A mode map was generated to locate the region of operating parameters for the design mode...

Spectral partitioning, eigenvalue bounds, and circle packings for graphs of bounded genus

Kelner, Jonathan, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 39 leaves; 1794456 bytes; 1796720 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
In this paper, we address two longstanding questions about finding good separators in graphs of bounded genus and degree: 1. It is a classical result of Gilbert, Hutchinson, and Tarjan [12] that one can find asymptotically optimal separators on these graphs if he is given both the graph and an embedding of it onto a low genus surface. Does there exist a simple, efficient algorithm to find these separators given only the graph and not the embedding? 2. In practice, spectral partitioning heuristics work extremely well on these graphs. Is there a theoretical reason why this should be the case? We resolve these two questions by showing that a simple spectral algorithm finds separators of cut ratio O(sqrt(g/n)) and vertex bisectors of size O(sqrt(gn)) in these graphs, both of which are optimal. As our main technical lemma, we prove an O(g/n) bound on the second smallest eigenvalue of the Laplacian of such graphs and show that this is tight, thereby resolving a conjecture of Spielman and Teng. While this lemma is essentially combinatorial in nature, its proof comes from continuous mathematics, drawing on the theory of circle packings and the geometry of compact Riemann surfaces.; by Jonathan Kelner.; Thesis (S.M.)--Massachusetts Institute of Technology...

Open-source social Network Assessment Survey System (NASS); NASS

Du, Aaron (Aaron Yinan)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 112 p.; 6889226 bytes; 6895749 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
The selection of targeted survey questions and the design of survey questionnaires are instrumental in the social networks research. With the accelerating growth of theory and experimental knowledge in the area of social network analysis, there is a need for a centralized questionnaire database system for the collection and appropriate utilization of these questions and feedbacks used for social networks research. Our project aims to provide a content-driven back-end database system and an online user interface to assist researchers to make intelligent selection of survey questions and design of questionnaires based on current area-specific knowledge within social network analysis.; by Aaron Du.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.; Includes bibliographical references (p. 49-50).

Approaches to multi-agent learning

Chang, Yu-Han, Ph. D., Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 171 leaves; 9090627 bytes; 9097798 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
661.31445%
Systems involving multiple autonomous entities are becoming more and more prominent. Sensor networks, teams of robotic vehicles, and software agents are just a few examples. In order to design these systems, we need methods that allow our agents to autonomously learn and adapt to the changing environments they find themselves in. This thesis explores ideas from game theory, online prediction, and reinforcement learning, tying them together to work on problems in multi-agent learning. We begin with the most basic framework for studying multi-agent learning: repeated matrix games. We quickly realize that there is no such thing as an opponent-independent, globally optimal learning algorithm. Some form of opponent assumptions must be necessary when designing multi-agent learning algorithms. We first show that we can exploit opponents that satisfy certain assumptions, and in a later chapter, we show how we can avoid being exploited ourselves. From this beginning, we branch out to study more complex sequential decision making problems in multi-agent systems, or stochastic games. We study environments in which there are large numbers of agents, and where environmental state may only be partially observable.; (cont.) In fully cooperative situations...