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Efficient numerical algorithms for surface formulations of mathematical models for biomolecule analysis and design

Bardhan, Jaydeep Porter, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 193 p.
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This thesis presents a set of numerical techniques that extend and improve computational modeling approaches for biomolecule analysis and design. The presented research focuses on surface formulations of modeling problems related to the estimation of the energetic cost to transfer a biomolecule from the gas phase to aqueous solution. The thesis discusses four contributions to modeling biomolecular interactions. First, the thesis presents an approach to allow accurate discretization of the most prevalent mathematical definitions of the biomolecule-solvent interface; also presented are a number of accurate techniques for numerically integrating possibly singular functions over the discretized surfaces. Such techniques are essential for solving surface formulations numerically. The second part of the thesis presents a fast multiscale numerical algorithm, FFTSVD, that efficiently solves large boundary-element method problems in biomolecule electrostatics. The algorithm synthesizes elements of other popular fast algorithms to achieve excellent efficiency and flexibility. The third thesis component describes an integral-equation formulation and boundary-element method implementation for biomolecule electrostatic analysis.; (cont.) The formulation and implementation allow the solution of complicated molecular topologies and physical models. Furthermore...

VMCStore : a TPM-based trusted storage framework; VMC Store : a TPM-based trusted storage framework

Rhodes, Jonathan M., M. Eng. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 67 p.
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This thesis introduces VMCStore, a framework for developing trusted storage applications on an untrusted server using a trusted platform module (TPM). The framework allows the server to provide trusted storage to a large number of clients, where each client may own and use several devices that may be offline at different times, and may not be able to communicate with each other, except through the untrusted server (over an untrusted network). The clients only trust the server's TPM; the server's BIOS, CPU, and OS are not assumed to be trusted. VMCStore draws on the ideas of virtual monotonic counters and validity proofs to provide tamper-evident storage, allowing the user to detect modifications to his data, as well as replay attacks. In particular, VMCStore uses TPM/J, a Java-based API for low-level access to the TPM, to create virtual monotonic counters using the monotonic counters and transport sessions of the TPM 1.2. VMCStore also provides a set of three log-based validation algorithms, which have been tested over PlanetLab and analyzed in this thesis. The VMCStore framework has been developed in a modular fashion, allowing the user to develop and test new applications and validation algorithms.; by Jonathan M. Rhodes.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

Sensor network localization based on natural phenomena

Kim, Daniel Sang
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 116 p.
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Autonomous localization is crucial for many sensor network applications. The goal of this thesis is to develop a distributed localization algorithm for the PLUG indoor sensor network by analyzing sound and light sensory data from naturally occurring background phenomena as well as synthesized emulations of background transients. Our approach has two main phases: passive and active. The system enters an active mode when, its sensed region stays relatively silent and stable, hence assumed to be unoccupied; otherwise, it stays in the passive mode. In the passive mode, each node looks for sonic transients and compares the timing of its highest sound peak to that of synchronized sound peaks from other nodes in its neighborhood in order to estimate its distance. Passive ranging achieved 50.96cm error and simulated passive localization achieved 103.06cm error with a typical node-spacing of 2m. In addition, the system exploits background transients based on light sensory data to determine room boundaries. In the active mode, each node occasionally generates recorded mimics of natural sonic transients, like pencils dropping or water glasses clinking and manipulates an attached light source. Active acoustic ranging achieved 2.1cm error and simulated active localization achieved 7.97cm error with a typical node-spacing of 2m. In addition...

Smart bookmarks : automatic retroactive macro recording on the web

Hupp, Darris
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 83 p.
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New technology has made the Web more dynamic and personalized, while at the same time interaction with the Web has become more complicated and involved. This thesis presents Smart Bookmarks, a web automation system that allows users to automate complex tasks or easily return to otherwise hard-to-reach dynamic web pages by creating smart bookmarks. A smart bookmark consists of an automatically generated script of recorded browsing commands that returns to a particular web page or web application state. Smart bookmarks can be created retroactively, meaning that the user does not need to explicitly initiate recording before performing a task, but can instead request a bookmark after visiting the destination page; the appropriate sequence of commands need to return to a page is selected automatically from a history of the user's browsing interactions. Smart Bookmarks provides a rich, visual representation of recorded bookmarks in order to clearly illustrate the actions that a bookmark performs, and includes textual descriptions, screenshots, and animated previews of each command. Finally, the system allows users to easily and intuitively edit bookmarks after they have been created, and to share smart bookmarks with other users.; by Darris Hupp.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

Design and implementation of the feedback systems Web laboratory

Viedma Núñez, Gerardo
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 103 p.; 4869087 bytes; 4873346 bytes; application/pdf; application/pdf
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This thesis describes the design and implementation of a remote web-based laboratory (WebLab) for MIT's 6.302 Feedback Systems course. The WebLab system proposed consists of a three-tiered architecture where client and server communicate with each other via web services. On the front end, the user interacts with the system through the Lab Client's graphical user interface implemented as a Java applet. On the back end, the Lab Server processes experiment requests from users and runs them at the laboratory site. Once the experiment has been completed successfully, the Lab Server sends the measured data to the Lab Client for display on the screen and further manipulation by the user. Furthermore, the WebLab is designed to take advantage of the iLab framework for provision of authentication and authorization services, as well as common administrative tasks, such as user management and logging of experimental results.; by Gerardo Viedma Núñez.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.; Includes bibliographical references (p. 99-103).

Prognostic models for mesothelioma : variable selection and machine learning

Vantzelfde, Nathan Hans
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 107 leaves; 6106147 bytes; 6110573 bytes; application/pdf; application/pdf
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Malignant pleural mesothelioma is a rare and lethal form of cancer affecting the external lining of the lungs. Extrapleural pneumonectomy (EPP), which involves the removal of the affected lung, is one of the few treatments that has been shown to have some effectiveness in treatment of the disease [39], but this procedure carries with it a high risk of mortality and morbidity [8]. This paper is concerned with building models using gene expression levels to predict patient survival following EPP; these models could potentially be used to guide patient treatment. A study by Gordon et al built a predictor based on ratios of gene expression levels that was 88% accurate on the set of 29 independent test samples, in terms of classifying whether or not the patients survived shorter or longer than the median survival [15]. These results were recreated both on the original data set used by Gordon et al and on a newer data set which contained the same samples but was generated using newer software. The predictors were evaluated using N-fold cross validation. In addition, other methods of variable selection and machine learning were investigated to build different types of predictive models. These analyses used a random training set from the newer data set. These models were evaluated using N-fold cross validation and the best of each of the four main types of models -; (cont.) decision trees...

Towards implementing group membership in dynamic networks : a performance evaluation study

Yuditskaya, Sophia
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 123 p.; 7428716 bytes; 7433828 bytes; application/pdf; application/pdf
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Support for dynamic groups is an integral part of the U.S. Department of Defense's vision of Network-Centric Operations. Group membership (GM) serves as the foundation of many group-oriented systems; its fundamental role in applications such as reliable group multicast, group key management, data replication, and distributed collaboration, makes optimization of its efficiency important. The impact of GM's performance is amplified in dynamic, failure-prone environments with intermittent connectivity and limited bandwidth, such as those that host military on the move operations. A recent theoretical result has proposed a novel GM algorithm, called Sigma, which solves the Group Membership problem within a single round of message exchange. In contrast, all other GM algorithms require more rounds in the worst case. Sigma's breakthrough design both makes and handles tradeoffs between fast agreement and possible transient disagreement, raising the question: how efficiently and accurately does Sigma perform in practice? We answer this question by implementing and studying Sigma in simulation, as well as two leading GM algorithms - Moshe and Ensemble - in a comparative performance analysis. Among the variants of Sigma that we study is Leader-Based Sigma...

Locally Decodable Codes and Private Information Retrieval Schemes; LDCs and PIRs

Yekhanin, Sergey
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 99 leaves
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This thesis studies two closely related notions, namely Locally Decodable Codes (LDCs) and Private Information Retrieval Schemes (PIRs). Locally decodable codes are error-correcting codes that allow extremely efficient, "sublinear-time" decoding procedures. More formally, a k-query locally decodable code encodes n-bit messages x in such a way that one can probabilistically recover any bit xi of the message by querying only k bits of the (possibly corrupted) code-word, where k can be as small as 2. LDCs were initially introduced in complexity theory in the context of worst-case to average-case reductions and probabilistically checkable proofs. Later they have found applications in numerous other areas including information theory, cryptography and the theory of fault tolerant computation. The major goal of LDC related research is to establish the optimal trade-off between length N and query complexity k of such codes, for a given message length n. Private information retrieval schemes are cryptographic protocols developed in order to protect the privacy of the user's query, when accessing a public database. In such schemes a database (modelled by an n-bit string x) is replicated between k non-communicating servers. The user holds an index i and is interested in obtaining the value of the bit xi. To achieve this goal...

Efficient and private distance approximation in the communication and streaming models

Woodruff, David Paul, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 114 p.
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This thesis studies distance approximation in two closely related models - the streaming model and the two-party communication model. In the streaming model, a massive data stream is presented in an arbitrary order to a randomized algorithm that tries to approximate certain statistics of tile data with only a few (usually one) passes over the data. For instance, the data may be a flow of packets on the internet or a set of records in a large database. The size of the data necessitates the use of extremely efficient randomized approximation algorithms. Problems of interest include approximating the number of distinct elements, approximating the surprise index of a stream, or more generally, approximating the norm of a dynamically-changing vector in which coordinates are updated multiple times in an arbitrary order. In the two-party communication model, there are two parties who wish to efficiently compute a relation of their inputs. We consider the problem of approximating Lp distances for any p > 0. It turns out that lower bounds on the communication complexity of these relations yield lower bounds on the memory required of streaming algorithms for the problems listed above. Moreover, upper bounds in the streaming model translate to constant-round protocols in the communication model with communication proportional to the memory required of the streaming algorithm. The communication model also hias its own applications...

Recombinant collagen production optimization in Escherichia coli

Whittemore, Brett A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 158 p.; 9563685 bytes; 9566105 bytes; application/pdf; application/pdf
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An Escherichia coli-based collagen-production process was used to investigate several process optimization objectives for use at the industrial scale. The effect of cooling on fermentation growth kinetics was studied, with preliminary results indicating that cooling an early to mid-batch phase fermentation (OD₆₀₀ = 2-4) to 10⁰C for up to 40 hours was not detrimental to the recovery of fermentation growth or the culture's ability to reach high cell density (OD₆₀₀> 50). A cost-effective assay of collagen-like polymer was examined under high-cell density conditions (as opposed to previously studied low density conditions) and an experimental design for tailoring the assay to high cell density fermentation samples is presented. In addition, a dual-plasmid strain of E. coli was designed for use in a novel process for the mass production of collagen-like polymers: one plasmid contains a thermally inducible recombinant collagen gene (CLP3.1-his), and the other contains an arabinose-inducible lytic gene (bacteriophage T4 t-holin) along with the basally expressed T7 lysozyme gene from the pLysS plasmid. A methodology for the optimization of the sequential induction of CLP3.1-his followed by induction of the t-holin is presented; a review of the literature suggests that decreased growth rate is detrimental to lytic efficiency (both the time required for lysis and the degree of lysis). The resulting process will enable lysis to take place in the bioreactor...

Optimizing neural networks for enhancing air traffic security; Building an optimized neural network for enhancing air safety

Cooney, Geoffrey T. (Geoffrey Thomas), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 163 leaves; 7390393 bytes; 7412147 bytes; application/pdf; application/pdf
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This thesis contains the process and results related to optimizing a neural network to predict future positions of airplanes in the vicinity of airports. These predicted positions are then used to calculate future separation distances between pairs of airplanes. The predicted values of the separation distance are used to ensure adequate distances between adjacent aircrafts in the air and, if necessary, to create early warning alarms to alert air traffic control tower personnel about planes that may pass too near each other in the immediate future. The thesis covers three areas of work on this topic. The first section involves optimizing a neural network for Chicago O'Hare Airport. The second is related to gathering data on the performance of this network in different scenarios. These data can be used to determine if the different days/runways have different characteristics. The final phase of this document describes how to generalize the process used to build an optimized neural network for Chicago O'Hare airport in order to provide the capability to easily recreate the process for another airport.; by Geoffrey T. Cooney.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science...

Broadcast-based communication in a programming environment for novices

Feinberg, David S. (David Scott), 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 88 p.; 3990309 bytes; 4000118 bytes; application/pdf; application/pdf
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This thesis proposes a model to make communication and processes in an object-oriented language accessible to novice programmers. For my thesis work, I developed a broadcast communication framework in the context of Scratch, an object-based programming language intended for children and being developed at the MIT Media Laboratory. Objects in this framework can broadcast events, which trigger other objects to start new processes. In this document, I identify the basic functionality required to support object communication in such a broadcast model, I describe my implementation of that functionality, and I consider the merits of various user interface metaphors to make these features accessible to novices. Finally, I compare the event broadcasting in this model with the use of procedures in more traditional programming languages, and raise questions as to whether the broadcast model's event handlers should supplement or supplant procedures in a beginner's programming language.; by David S. Feinberg.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (p. 87-88).

Versioning for the Haystack system

D'Aleo, Dominic J. (Dominic Joseph), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 76 leaves; 3472306 bytes; 3480195 bytes; application/pdf; application/pdf
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In this thesis, the design and implementation of a repository for electronic information is presented. While designed with the Haystack system in mind, the repository can easily be used by anyone familiar with RDF. This repository performs the basic task of storing the information that the user collects, in addition to automatically performing several other tasks in an effort to make retrieving the information simple and efficient. The additional tasks involve the storing of when and why information enters the repository. The hope is that this additional data will help the user when searching their repository. A person's sense of time and data dependence is a strong organizing princple that can help them locate a file simply because they remember when or why they archived it, or perhaps when they used it last. This repository allows a user to narrow the search of their information space in regards to time and dependence.; by Dominic J. D'Aleo.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2002.; Includes bibliographical references (leaves 75-76).

Iterative blind separation of Gaussian data of unknown order

Mueller, Amy, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 126 p.; 5589269 bytes; 5604784 bytes; application/pdf; application/pdf
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A method for blind separation of noisy jointly Gaussian multivariate signals X is presented, where X = AP + N, X is an observed set of vectors, A is the mixing matrix, P is the unknown signal matrix, and N is white noise. The objective is to estimate all matrices on the right-hand side when even their dimensions (the system order) are unknown. The algorithms developed are extensions of the Iterative Order and Noise (ION) estimation algorithm [10]. Improvements made within the iterative structure of ION to better estimate the order and noise yield ION'. The addition of a second-order blind identification algorithm (SOBI, [4]) subsequently yields ONA, which fully characterizes a data set by estimating the (O)rder, (N)oise, and mixing matrix (A). Metrics are developed to evaluate the performance of these algorithms, and their applicability is discussed. Optimum algorithm constants for ION' and ONA are derived, and their range of applicability is outlined. The algorithms are evaluated through application to three types of data: (1) simulated Gaussian data which spans the problem space, (2) a set of non-Gaussian factory data with 577 variables, and (3) a hyperspectral image with 224 channels. The ONA algorithm is extended to 2D (spatial) hyperspectral problems by exploiting spatial rather than time correlation. ONA produces a full characterization of the data with high signal-to-noise ratios for most unknown parameters in the Gaussian case...

Resource allocation and scheduling for communication satellites with advanced transmission antennas

Choi, Jihwan Patrick, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 180 p.
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For multimedia and other data services over satellite networks, the efficient management of scarce satellite communication resources is critical for the economic competitiveness of the medium. To support a broad spectrum of users with small terminals at high data rates, narrow transmit spotbeams from the satellite must be used. Since satellite on-board resources are too expensive to illuminate all of the spotbeam-coverage cells within the satellite service area, an optimized method of agile antenna gain patterning and beam scheduling is required to greatly improve the efficiency of transmission and power management. In this thesis, we jointly optimize resource allocation/scheduling, congestion control and antenna gain patterning for communication satellites with advanced transmission antennas. Then, we develop a low-complexity on-line algorithm that considers channel conditions, interference and average delay constraints, and approaches the theoretical steady-state limit. We introduce optimized beam profiling based on traffic demand and channel conditions over satellite downlinks, which can achieve a substantial power gain and reasonable proportional fairness. We show that a modest number of active parallel beams are sufficient to cover many cells efficiently with dynamic capacity allocation.; (cont.) Next...

On constructing correct and scalable iBGP configurations

Vutukuru, Mythili
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 53 p.
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BGP (Border Gateway Protocol), the Internet's current inter-domain routing protocol, has two modes of operation: eBGP (external BGP, used to exchange routing information between autonomous systems (ASes)), and iBGP (internal BGP, used to propagate that information about external destinations to other BGP routers within an AS). Full-mesh iBGP and iBGP with route reflection are the two most common methods of configuring iBGP. Although a full-mesh iBGP guarantees correct and predictable routing, it requires a large number of iBGP sessions-approximately quadratic in the number of BGP routers. Such configurations do not scale well in the number of BGP routers in the AS because of the memory, bandwidth and CPU overhead involved in exchanging routes over a large number of iBGP sessions at each router. Hence configurations based on route reflectors are commonly used for intra-AS route dissemination in large ASes. However, researchers have found that configuring route reflectors in an unprincipled fashion can result in routing anomalies like forwarding loops and sub-optimal paths. Although previous work on iBGP configuration correctness gives sufficient conditions to check if a given iBGP configuration is correct, the problem of constructing correct and scalable iBGP configurations using route reflection has not received much attention.; (cont.) This thesis proposes and analyzes the first (to our knowledge) algorithm to construct iBGP session configurations that are both correct and more scalable than a full-mesh iBGP. Our algorithm...

Low-noise electronic readout for high-throughput, portable biomolecular detection in microchannel arrays

Chunara, Rumi
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 58 leaves
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There's not much that can be done to make research easier - but excitement and passion are two key elements of success, and two of the many things I have learned from my advisor, Scott Manalis. It has been (and will continue to be) an awesome opportunity that I am especially thankful for, to work in nanoscale sensing with him. Perhaps the next best thing to a great advisor is having friends to work with who are equally as excited as me, more experienced, and many times smarter. I am forever indebted to all the members of the lab who have contributed to my biggest asset - knowledge. Special respect to those who bestow humour with the facts: Nebojsa, Johnson, Mike, Phil, and of course Thomas without whom I would have been in the lab a lot longer and in Europe a lot less. Thanks for coming to lab with a smile and for helping me leave with one. Places like MIT are excellent institutions, mostly because of their students. I am thankful to all of the graduate students in other labs which are always glad to give some words of advice or spend a few hours explaining something not so trivial to me. Especially to those in Professor Rahul Sarpeshkar's laboratory, especially Soumya and Scott. I am also very lucky to have great friends outside of the lab...

Transmission and reflection properties of layered left-handed materials

Chen, Jianbing James, 1971-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 189 p.
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This thesis is concerned with the reflection and transmission properties of layered left-handed materials (LHM). In particular, the reflection properties of (LHM) slabs are studied for the Goos-Hanchen (GH) lateral shift phenomenon. We demonstrate a unique GH lateral shift phenomenon, which shows that both positive and negative shifts can be achieved using the same LHM slab configuration. This phenomenon is different from previously established cases where the GH lateral shift can be only negative or only positive when different LHM slab configurations are used. We also show that there exist two distinct cases with this unique phenomenon. One case has two regions of incident angles where the GH lateral shift directions are different, while another case has three regions with alternated GH shift directions. A generalized analytical formulation for analyzing the GH lateral shift direction is provided, which reveals that this unique phenomenon is related to the relative amplitudes of the growing and decaying evanescent waves inside the LHM slabs. The energy flux patterns within LHM slabs are further studied to show the influence of the evanescent waves on the GH shift direction change.; (cont.) Furthermore, the transmission property of LHM slabs are studied on the finite slabs' maging capability. First...

Optical frequency domain imaging of human retina and choroid; OFDI of human retina and choroid

Lee, Edward Chin Wang
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 87, [1] p.
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Optical coherence tomography (OCT) has emerged as a practical noninvasive technology for imaging the microstructure of the human eye in vivo. Using optical interferometry to spatially-resolve backreflections from within tissue, this high-resolution technique provides cross-sectional images of the anterior and posterior eye segments that had previously only been possible with histology. Current commercially-available OCT systems suffer limitations in speed and sensitivity, preventing them from effective screening of the retina and having a larger impact on the clinical environment. While other technological advances have addressed this problem, they are inadequate for imaging the choroid, which can be useful for evaluating choroidal disorders as well as early stages of retinal diseases. The objective of this thesis was to develop a new ophthalmic imaging method, termed optical frequency domain imaging (OFDI), to overcome these limitations. Preliminary imaging of the posterior segment of human eyes in vivo was performed to evaluate the utility of this instrument for comprehensive ophthalmic examination.; (cont.) The 1050-nm OFDI system developed for this thesis comprised a novel wavelength-swept laser that delivered 2.7 mW of average power at a sweep rate of 18.8 kHz...

High-speed silicon electro-optic modulator for electronic photonic integrated circuits

Gan, Fuwan
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 184 p.
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The development of future electronic-photonic integrated circuits (EPIC) based on silicon technology critically depends on the availability of CMOS-compatible high-speed modulators that enable the interaction of electronic and optical signals. This thesis investigates electrically driven Mach-Zehnder modulators based on high-index contrast silicon waveguide technology and electronic carrier injection. Modulators based on four different structures are investigated: the forward-biased PiN diode with and without lifetime reduction, the reverse-biased PIN/PN diode and a metal-oxide-semiconductor (MOS) structure. These devices are compared with each other in terms of achievable performance. A modulator based on the forward-biased PIN diode with lifetime reduction is designed to reach 34GHz bandwidth and a low figure of merit V -. L = 0.6V - cm using a carrier lifetime reduction and a graded doping profile. A bandwidth of 1-2GHz has been demonstrated so far which is considerably smaller than the design bandwidth due to high series resistance. Modulators based on the forward-biased PIN structure without lifetime reduction have a low figure of merit, very low voltage and extremely low power consumption in the low frequency regime.; (cont.) The measurements demonstrate a RF power consumption of 100mW for 25% modulation depth and a figure of merit of V...