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‣ Fluorescence assay for polymerase arrival rates

Che, Austin, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 100 p.; 2370513 bytes; 2372070 bytes; application/pdf; application/pdf
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To engineer complex synthetic biological systems will require modular design, assembly, and characterization strategies. The RNA polymerase arrival rate (PAR) is defined to be the rate that RNA polymerases arrive at a specified location on the DNA. Designing and characterizing biological modules in terms of RNA polymerase arrival rates provides for many advantages in the construction and modeling of biological systems. PARMESAN is an in vitro method for measuring polymerase arrival rates using pyrrolo-dC, a fluorescent DNA base that can substitute for cytosine. Pyrrolo-dC shows a detectable fluorescence difference when in single-stranded versus double-stranded DNA. During transcription, RNA polymerase separates the two strands of DNA, leading to a change in the fluorescence of pyrrolo-dC. By incorporating pyrrolo-dC at specific locations in the DNA, fluorescence changes can be taken as a direct measurement of the polymerase arrival rate.; by Austin Che.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2004.; Includes bibliographical references (p. 87-100).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Reliability and energy-efficiency in wireless ad-hoc networks

Srinivas, Anand, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 83 p.; 924798 bytes; 472350 bytes; application/pdf; application/pdf
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In this thesis, we address issues related to reliability and energy-efficiency in wireless ad hoc networks. In the first part of the work, we deal with the problem of simultaneously routing data along multiple disjoint paths from a source to destination in the most energy efficient manner. To this end, we developed and analyzed both optimal and heuristic algorithms that find minimum energy node and link disjoint paths in a wireless ad hoc network. Our major results include a novel polynomial time algorithm that optimally solves the minimum energy 2 link-disjoint paths problem, as well as a polynomial time algorithm for the minimum energy k node-disjoint paths problem. Additionally, we demonstrate via simulation that when disjoint path routing is employed, network lifetime is significantly extended when our routing algorithms (in combination with a simple heuristic) are used. In the second part of the work, we deal with a slightly different reliability problem. In particular, we consider the problem of how to best ensure that QoS sessions (e.g. those with a minimum capacity requirement) do not get dropped after their primary path has failed. Our methodology is to attempt to eliminate one potential cause of session drops, i.e. the inability for the interrupted session to find a backup path with sufficient capacity. To this end...

‣ WSIM configurable digital signal processor simulator/debugger; WSIM configurable DSP simulator/debugger

Ni, Wayland, 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 57 leaves; 308619 bytes; 308357 bytes; application/pdf; application/pdf
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This M.Eng. Thesis presents a design and implementation of a full-featured configurable Digital Signal Processor (DSP) simulator/debugger. The user will be able to set configurations in order to model a specific architecture design. The simulator will have a command interpreter to listen to and process commands given by the user. When supplied with an assembly program, the simulator will allow the user to step through the execution of the program cycle by cycle, as well as calculate statistics like instruction, resource, and cache profiling. Some of the main features of the simulator are a multiply-accumulate unit, memory with direct and indirect offset addressing, and loop instructions.; by Wayland Ni.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (leaf 53).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Design and control of photoflash capacitor charging circuits; Design and control of photoflash capacitor sharing circuits

Negrete, Michael G. (Michael George), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 112 leaves; 741984 bytes; 619612 bytes; application/pdf; application/pdf
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This thesis develops an optimal strategy for charging photoflash capacitors. Photoflash capacitors need to be charged to voltages as high as 350V in low-voltage battery-powered portable devices. With the decreasing size of digital cameras, existing solutions are too large. This thesis will study the operation and losses of a flyback capacitor charger. Specifically, the thesis will focus on minimizing the solution size, given an input current, in addition to keeping efficiency acceptable.; by Michael G. Negrete.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (leaves 111-112).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Dynamic Bayesian networks for the classification of spinning discs

Schmidt, Aurora Clare, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 89 p.; 3354906 bytes; 3358243 bytes; application/pdf; application/pdf
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This thesis considers issues for the application of particle filters to a class of nonlinear filtering and classification problems. Specifically, we study a prototype system of spinning discs. The system combines linear dynamics describing rotation with a nonlinear observation model determined by the disc pattern, which is parameterized by angle. A consequence of the nonlinear observation model is that the posterior state distribution of angle and spin-rate is multi-modal. This detail motivates the use of particle filtering. Practical issues that we consider when using particle filters are sample depletion and sample degeneracy, both of which lead to poor representations of the state distributions. Variance based resampling and regularization are common methods to mitigate sampling issues in particle filtering. We investigate these methods empirically for our prototype problem. Specific parameters of interest relating to these methods are the number of particles used to approximate the posterior distribution, quantitative methods for deciding when to resample, choice of regularization variance, the impact of measurement noise on all of these, and performance over time. A common issue, leading to inaccurate sample-based representations...

‣ Application of three-dimensional circuit integration to global clock distribution

Salinas, Erica M. (Erica Marie), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 37 leaves; 371157 bytes; 430737 bytes; application/pdf; application/pdf
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As the semi-conductor industry moves towards deep sub-micron designs, efficiency of chip-wide communication is becoming the limiting factor on system performance. One globally distributed signal with significant effect on system performance is the clock signal. In this paper utilization of three-dimensional circuit integration to reduce the negative effects of technology scaling on clock signal distribution is investigated. A design is proposed that removes the clock distribution network from the same active plane as the logical functions of the system and places them on a separate, but electrically connected active plane. Proposed benefits of a three-dimensional distribution network are the reduction of global skew, greater signal integrity, and an increase in system density. All aspects of the design process are detailed including methodology, simulation tools and verification, interconnect and repeater design, the three-dimensional integration process, and the overall predicted system benefits.; by Erica M. Salinas.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, February 2004.; Includes bibliographical references (leaf 35).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ An ultrasonic compass for context-aware mobile applications

Wang, Kevin John, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 96 p.; 2166984 bytes; 4546225 bytes; application/pdf; application/pdf
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If we are to realize the everyday benefits promised by pervasive computing and context-aware applications, we must first develop the infrastructure to provide contextual location and orientation information through pervasive computing elements. I lay the foundations for leveraging the Cricket indoor location system to supply orientation information. I first characterize the use of ultrasound in Cricket for distance and orientation measurements. I then propose a set of methods to calculate 3-DOF orientation from an array of well placed ultrasonic sensors operating in the Cricket system. I design and implement a prototype of this Cricket Compass using a combination of hardware and software and demonstrate end-to-end functionality of the system.; by Kevin John Wang.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (p. 95-96).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Radio frequency rectifiers for DC-DC power conversion; Radio frequency rectifiers for direct current-direct current power conversion

Wahby, Riad Samir, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 120 p.; 587649 bytes; 587357 bytes; application/pdf; application/pdf
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A significant factor driving the development of power conversion technology is the need to increase performance while reducing size and improving efficiency. In addition, there is a desire to increase the level of integration of DC-DC converters in order to take advantage of the cost and other benefits of batch fabrication techniques. While advances in the power density and integration of DC-DC converters have been realized through development of better active device technologies, much room for improvement remains in the size and fabrication of passive components. To achieve these improvements, a substantial increase in operating frequency is needed, since intermediate energy storage requirements are inversely proportional to frequency. Unfortunately, traditional power conversion techniques are ill-suited to handle this dramatic escalation of switching frequency. New architectures have been proposed which promise to deliver radical performance improvements while potentially reaching microwave frequencies. These new architectures promise to enable substantial miniaturization of DC-DC converters and to permit much a higher degree of integration. The principal effort of this thesis is the development of design and characterization methods for rectifier topologies amenable to use in the new architectures. A computational design approach allowing fast and accurate circuit analysis and synthesis is developed and applied...

‣ Training architectural computational critics by example

Williams, Reid E. (Reid Edward), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 92 p.; 1585238 bytes; 12748355 bytes; application/pdf; application/pdf
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New building technologies and materials coupled with a modular construction system offer consumers an unprecedented chance to customize their living spaces. At the center of this customization process is a computational tool that guides consumers through the process of designing a home or apartment. Algorithms for architectural computational critics that are trained by a designer through examples and that can then critique designs is proposed as part of the design tool. A prototype system encompassing two apartment design scenarios is built and tested. The prototype demonstrates the ability to learn architectural concepts through training.; by Reid E. Williams.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2003.; Includes bibliographical references (p. 63-65).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Maximizing degrees of freedom in wireless networks

Borade, Shashibhushan Prataprao, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 76 p.; 489595 bytes; 438134 bytes; application/pdf; application/pdf
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We consider communication from a single source to a single destination in a wireless network with fading. Both source and destination have multiple antennas. The information reaches the destination through a sequence of layers of single-antenna relays. A non-separation-based strategy is proposed and shown to achieve a rate equal to the capacity of a point-to-point multiantenna system in the high SNR regime. This implies that lack of coordination between relay nodes does not reduce the achievable rate at high SNR. We then derive the tradeoffs between network size and rate. We also derive the rate-diversity tradeoff for this network and study how it is affected by the network size. This shows that increasing network size is much more difficult when the codelength does not span a large number of fading realizations. Finally some implications to ad-hoc networks are discussed.; by Shashibhushan Prataprao Borade.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (p. 61-63).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Global estimation of precipitation using opaque microwave bands

Chen, Frederick Wey-Min, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 125 p.; 6131559 bytes; 3591649 bytes; application/pdf; application/pdf
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This thesis describes the use of opaque microwave bands for global estimation of precipitation rate. An algorithm was developed for estimating instantaneous precipitation rate for the Advanced Microwave Sounding Unit (AMSU) on the NOAA-15, NOAA-16, and NOAA-17 satellites, and the Advanced Microwave Sounding Unit and Humidity Sounder for Brazil (AMSU/HSB) aboard the NASA Aqua satellite. The algorithm relies primarily on channels in the opaque 54-GHz oxygen and 183-GHz water vapor resonance bands. Many methods for estimating precipitation rate using surface-sensitive microwave window channels have been developed by others. The algorithm involves a set of signal processing components whose outputs are fed into a neural net to produce a rain rate estimate for each 15-km spot. The signal processing components utilize techniques such as principal component analysis for characterizing groups of channels, spatial filtering for cloud-clearing brightness temperature images, and data fusion for sharpening images in order to optimize sensing of small precipitation cells. An effort has been made to make the algorithm as blind to surface variations as possible. The algorithm was trained using data over the eastern U.S. from the NEXRAD ground-based radar network...

‣ Multipath aided rapid acquisition

Suwansantisuk, Watcharapan, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 125 p.; 615537 bytes; 611114 bytes; application/pdf; application/pdf
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Spread-spectrum systems with large transmission bandwidth present significant challenges from the standpoint of achieving synchronization before communication commences. This research investigates a rapid acquisition procedure that exploits the multipath to aid the synchronization. In particular, we consider a class of serial search strategies and determine the optimal search procedure for the uncertainty space consisting of N[sub]s total cells and N[sub]Q correct cells. We derive closed-form expressions for both the minimum and maximum mean acquisition times (MATs) and the conditions for achieving these limits. We prove that the fixed-step serial search (FSSS), with the step size N[sub]Q, achieves the near-optimal MAT. We also prove that the conventional serial search, in which consecutive cells are tested sequentially, and the FSSS with the step size N[sub]s - 1 should be avoided as they result in the maximum MAT. Analytical tools used in the research include Markov chain diagrams, the transformation of feasible spaces, and convexity theory. Our results apply to all signal-to-noise ratio values, regardless of the detection-layer decision rule and the fading distribution. The impact of this research is significant for the design, implementation...

‣ Diversity with practical channel estimation in arbitrary fading environments

Gifford, Wesley M. (Wesley Michael), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 83 p.; 475491 bytes; 474953 bytes; application/pdf; application/pdf
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This thesis presents a framework for evaluating the bit error probability of Nd-branch diversity combining in the presence of non-ideal channel estimates. The estimator structure is based on the maximum likelihood (ML) estimate and arises naturally as the sample mean of Np pilot symbols. The framework presented requires only the evaluation of a single integral involving the moment generating function of the norm square of the channel gain vector, and is applicable to channels with arbitrary distribution, including correlated fading. Analytical results show that the practical ML channel estimator preserves the diversity order of an Nd-branch diversity system, contrary to conclusions in the literature based upon a model that assumes a fixed correlation between the channel and its estimate. Finally, the asymptotic signal-to-noise ratio (SNR) penalty due to estimation error is investigated. This investigation reveals that the penalty has surprisingly little dependence on the number of diversity branches.; by Wesley M. Gifford.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (p. 79-83).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Determining molecular conformation from distance or density data

Wang, Cheuk-san, 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 130 p.; 2400582 bytes; 2400339 bytes; application/pdf; application/pdf
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The determination of molecular structures is of growing importance in modern chemistry and biology. This thesis presents two practical, systematic algorithms for two structure determination problems. Both algorithms are branch-and-bound techniques adapted to their respective domains. The first problem is the determination of structures of multimers given rigid monomer structures and (potentially ambiguous) intermolecular distance measurements. In other words, we need to find the the transformations to produce the packing interfaces. A substantial difficulty results from ambiguities in assigning intermolecular distance measurements (from NMR, for example) to particular intermolecular interfaces in the structure. We present a rapid and efficient method to simultaneously solve the packing and the assignment problems. The algorithm, AmbiPack, uses a hierarchical division of the search space and the branch-and-bound algorithm to eliminate infeasible regions of the space and focus on the remaining space. The algorithm presented is guaranteed to find all solutions to a pre-determined resolution. The second problem is building a protein model from the initial three dimensional electron density distribution (density map) from X-ray crystallography. This problem is computationally challenging because proteins are extremely flexible.; (cont.) Our algorithm...

‣ Subword-based approaches for spoken document retrieval

Ng, Kenney, 1967-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 187 p.; 835758 bytes; 835515 bytes; application/pdf; application/pdf
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This thesis explores approaches to the problem of spoken document retrieval (SDR), which is the task of automatically indexing and then retrieving relevant items from a large collection of recorded speech messages in response to a user specified natural language text query. We investigate the use of subword unit representations for SDR as an alternative to words generated by either keyword spotting or continuous speech recognition. Our investigation is motivated by the observation that word-based retrieval approaches face the problem of either having to know the keywords to search for [em a priori], or requiring a very large recognition vocabulary in order to cover the contents of growing and diverse message collections. The use of subword units in the recognizer constrains the size of the vocabulary needed to cover the language; and the use of subword units as indexing terms allows for the detection of new user-specified query terms during retrieval. Four research issues are addressed. First, what are suitable subword units and how well can they perform? Second, how can these units be reliably extracted from the speech signal? Third, what is the behavior of the subword units when there are speech recognition errors and how well do they perform? And fourth...

‣ JET : an application of partial evaluation in dynamic code generation for Java; Application of partial evaluation in dynamic code generation for Java

Chao, Tony (Tony Hann-Ching), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 66 p.; 177989 bytes; 177741 bytes; application/pdf; application/pdf
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by Tony Chao.; Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.; Includes bibliographical references (p. 64-66).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Automating component-based testing from UML models; Automating component-based testing from Unified Modeling Language models

Che, Bryan (Bryan Wan-Jen), 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 43 leaves; 349231 bytes; 348961 bytes; application/pdf; application/pdf
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by Bryan Che.; Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.; Includes bibliographical references (leaf 43).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ A custom computing framework for orientation and photogrammetry

Fiore, Paul D. (Paul David), 1963-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 223 p.; 2600672 bytes; 2587295 bytes; application/pdf; application/pdf
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by Paul D. Fiore.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.; Includes bibliographical references (p. 211-223).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Power velocity integral technique for quantification of flow in valvular heart disease

Hwang, Shawn M. (Shawn Meanshing), 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 153 leaves; 18437862 bytes; 18437600 bytes; application/pdf; application/pdf
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by Shawn M. Hwang.; Thesis (S.B. and M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.; Includes bibliographical references (leaves 147-150) and indexes.; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Peak power reduction algorithms in ADSL modems; Peak power reduction algorithms in asymmetric digital subscriber line modems

Dousis, Athanasios Dimitri, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 96 leaves; 622258 bytes; 622010 bytes; application/pdf; application/pdf
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by Athanasios Dimitri Dousis.; Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2000.; Includes bibliographical references (leaves 94-96).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.