Recursos de colección

DSpace at MIT (102.107 recursos)

This site is a university repository providing access to the publication output of the institution. Registered users can set up email alerts to notify them of newly added relevant content. A certain level of encryption and security is embedded in the site which may cause some users accessibility problems.

Electrical Engineering and Computer Sciences - Master's degree

Mostrando recursos 1 - 20 de 6.572

  1. Prediction of velocity distribution from the statistics of pore structure in 3D porous media via high-fidelity pore-scale simulation

    AlAdwani, Mohammad S. Kh. F. Sh
    Fluid flow and particle transport through porous media are determined by the geometry of the host medium itself. Despite the fundamental importance of the velocity distribution in controlling early-time and late-time transport properties (e.g., early breakthrough and superdiffusive spreading), direct relations linking velocity distribution with the statistics of pore structure in 3D porous media have not been established yet. High velocities are controlled by the formation of channels, while low velocities are dominated by stagnation zones. Recent studies have proposed phenomenological models for the distribution of high velocities including stretched exponential and power-exponential distributions but without an underlying mechanistic or...

  2. Decentralized infrastructure for file storage

    Greco, Nicola, S.M. Massachusetts Institute of Technology
    How might we incentivize a peer-to-peer network to store users' files? The purpose of this research is to combine ideas from existing peer-to-peer file sharing systems, blockchain technology and Proofs-of-Storage to create an incentivized decentralized storage network, where every participant can earn a reward for storing and serving files or pay the network to store or retrieve their own. More broadly, in this thesis we present the elementary components for building decentralized infrastructure, culminating in a protocol for incentivizing file storage.

  3. The Traveling Salesman Problem and orienteering for kinodynamic vehicles

    Adler, Aviv
    The Traveling Salesman Problem is a major foundational problem in the fields of Computer Science, Operations Research, and Applied Mathematics, in which an agent wants to visit a set of target points with the shortest path possible. This problem is of the highest interest both theoretically in practice. When the agent is a vehicle whose trajectory must satisfy a set of dynamic constraints and the target points are distributed over a continuous space, this problem is especially relevant to robotics. Although this problem is considered computationally intractable to solve precisely, in many settings a good approximate path can be computed...

  4. Scalable design of high-performance on-chip Terahertz source and imager

    Hu, Zhi, S.M. Massachusetts Institute of Technology
    In this thesis, two chip designs using the scalable array architecture are introduced. Firstly, we introduce a scalable architecture of coherent harmonic oscillator array for high-power and collimated radiation beam at mid-THz band. The array is 2D-coupled, and each element achieves these functions: (i) maximize oscillation at fundamental frequency fo= 2 50 GHz; (ii) synchronize phase of fo and its harmonics among elements; (iii) cancel near-field radiation of fo, 2fo and 3fo, and (iv) efficiently radiate at 4fo and combine power in free space. The resultant compact design fits into the optimal radiator pitch of [lambda]/2 (half wavelength) for side-lobe...

  5. Topology hiding computation on all graphs

    LaVigne, Rio (Kristen Rio)
    A distributed computation in which nodes are connected by a partial communication graph is called topology-hiding if it does not reveal information about the graph beyond what is revealed by the output of the function. Previous results have shown that topology-hiding computation protocols exist for graphs of constant degree and logarithmic diameter in the number of nodes [Moran-Orlov-Richelson, TCC'15; Hirt et al., Crypto'16] as well as for other graph families, such as cycles, trees, and low circumference graphs [Akavia-Moran, Eurocrypt'17], but the feasibility question for general graphs was open. In this work we positively resolve the above open problem: we...

  6. Estimation of clinical trial success rates and related parameters

    Wong, Chi Heem
    Previous estimates of drug development success rates rely on relatively small samples of pharmaceutical industry-curated databases, which are subject to potential sample selection biases. Using a sample of 185,994 unique entries of clinical-trial data for over 21,143 compounds from January 1st, 2000 to October 31st, 2015, we estimate aggregate success rates and durations of clinical trials. We also compute disaggregated estimates by stratifying across several features including: disease type, clinical phase, industry/academic sponsor, biomarker presence, lead indication status, and over time. In several cases, our results differ significantly from widely cited statistics. For example, oncology has a 3.4% success rate...

  7. Terahertz beam-steering imager using a scalable 2D-coupled architecture and multi- functional heterodyne pixels

    Zhang, Guo, S.M. Massachusetts Institute of Technology
    The topic covered by this thesis is the project of designing a terahertz imager chip on nowadays commercialized mature silicon platform. In the project, we developed the design method of a multi-functional heterodyne pixel and a scalable array architecture. The pixel is a compact electromagnetic structure simultaneously performs voltage-controlled 140 GHz local oscillation, 280-GHz-signal receiving, sub-harmonic mixing, and intermediate frequency (IF) signal extraction. Each pixel consumes 10 mW power and achieves a sensitivity of 2.9 pW in simulation. The local oscillator (LO) of the pixel is phase coupled with its neighbors; the whole oscillator array is then stabilized by an...

  8. Skin friction drag reduction in turbulent flows using superhydrophobic surfaces

    Rajappan, Anoop
    The use of randomly textured superhydrophobic surfaces have recently gained interest as a potential approach for the passive reduction of skinfriction on the hull of ships, submarines and underwater projectiles. When submerged in water, these surfaces trap a layer of air (or 'plastron') within their texture, which allows the external fluid to partially slip over the boundary, decreasing the net frictional shear stress on the wall. Five prototype drag-reducing surfaces were evaluated experimentally as possible candidates for turbulent drag reduction applications, using a combination of flow tests, surface profile measurements, and contact angle goniometry. Three of these were randomly rough...

  9. Microwave response of nonlinear oscillations in resistively shunted superconducting nanowires

    Toomey, Emil
    Many superconducting technologies such as rapid single flux quantum computing (RSFQ) and superconducting quantum interference devices (SQUIDs) rely on the modulation of nonlinear dynamics in Josephson junctions for functionality. More recently, however, superconducting devices have been developed based on the switching and thermal heating of nanowires for use in fields such as single photon detection and digital logic. In this Master's thesis, I will use resistive shunting to control the nonlinear heating of a superconducting nanowire and compare the resulting dynamics to those observed in Josephson junctions. In particular, I will use a microwave drive to modulate the nonlinear behavior...

  10. Investigating social media usage patterns and privacy awareness with composite data visualization

    Yuan, Ben Z. (Ben Ze)
    This thesis describes an investigation into the degree of awareness people have of their activity and audience on social media, and into the alignment of sharing expectations with actual sharing behavior. It is previously reported that people tend to share problematic posts on social media networks because they are not always aware of who can actually see their posts and other activity and do not always apply privacy settings effectively. We built a data collection tool that gathers social media data, like posts, connections, and private messages, from Facebook, Twitter, Instagram, and LinkedIn, and assembles a composite profile combining information...

  11. Long-wave infrared frequency combs based on quantum cascade lasers

    Zeng, Tianyi
    Ever since the invention of quantum cascade laser (QCL), the performance and the flexibility in design has made it a desirable source for a wide range of applications, such as trace-chemical sensing, health monitoring, frequency metrology, noninvasive imgaing and infrared countermeasures. The LWIR region (or mid-infrared region), roughly ranging from 2-20 [mu]m, is of particular importance to spectroscopy applications, since many molecular species have their strongest rotational-vibrational absorption bands in that area. Infrared laser spectroscopy began about 40 years ago and has been using a variety of different tunable laser-based sources, particularly lead salt diodes, color center lasers, difference frequency...

  12. Thirteen ways of looking : a theoretical inquiry in computational creative thinking

    Turakhia, Dishita Girish
    The vision of this research is to propose a novel computational framework to study Creative Thinking. If we are to embed machines with creative thinking abilities, then we first need to study the evanescent nature of human creative thinking. Creative thinking is neither entirely random nor strictly logical, making it difficult to t its computation into structured logical models of thinking. Given this conundrum, how can we computationally study the process of thinking creatively? In this research, I first present the current scientific definitions of creative thinking. Through literary survey of cognitive, computational and design thinking frameworks, I identify the...

  13. Low frequency active sonar performance in the Arctic Beaufort Lens

    Carper, Scott Adams
    A newly discovered double ducted acoustic environment present throughout much of the Beaufort Sea in the Arctic has a major effect on active acoustic transmissions. This work performs an in depth analysis of how the lower duct impacts the propagation of various active signals used commonly for acoustic communications or active sonar. First, this thesis performs a thorough modal analysis of the effect of the double ducted environment on long range propagation of a 300 Hz and 3500 Hz pulse. Signal excess is determined for the two different source pulses to quantify the effect of the lower duct on noise...

  14. Automatic 3D surface area measurement for vitiligo lesions

    Huang, Jiarui, M. Eng. Massachusetts Institute of Technology
    Vitiligo is a long term skin depigmentation disease that may result in psychological stress. Monitoring changes in vitiligo lesion area allows assessment of treatment efficacy and aids in clinical decision making. Currently existing approaches for vitiligo lesion measurement are either inefficient or inaccurate. Using a RGB-D camera (Kinect) and imaging processing techniques, we develop an automated skin lesion screening system (VLAMS) that can be widely adopted in clinics. VLAMS is tested using clinical medical data. Results show VLAMS can consistently segment target lesion region and accurately measure lesion area of any skin surface.

  15. SibylFuzzer : stateful fuzzing for file systems

    Zuo, Catherine (Catherine W.)
    Correct file system behavior is vital to developing robust higher-level software and applications. However, correctly and efficiently investigating the wide range of file system behavior makes testing file systems a difficult task. In this thesis, I designed and implemented SibylFuzzer, a stateful fuzzer for testing file system behavior. Sibyl- Fuzzer is based on SibylFS, a third-party system comprised of a model for acceptable file system behavior and a procedure for comparing real-life file system implementation behavior against that model. SibylFuzzer uses SibylFS in two ways: first, as a source of file system knowledge to produce in-depth and meaningful tests; second,...

  16. ModelDB : tools for machine learning model management and prediction storage

    Viswanathan, Srinidhi
    Building a machine learning model is often an iterative process. Data scientists train hundreds of models before finding a model that meets acceptable criteria. But tracking these models and remembering the insights obtained from them is an arduous task. In this thesis, we present two main systems for facilitating better tracking, analysis, and querying of scikit-learn machine learning models. First, we introduce our scikit-learn client for ModelDB, a novel end-to-end system for managing machine learning models. The client allows data scientists to easily track diverse scikit-learn workflows with minimal changes to their code. Then, we describe our extension to ModelDB,...

  17. High voltage sampling scheme independent of capacitor voltage coefficient for a delta sigma modulator

    Uyehara, Chad P
    The rapidly growing market of electric vehicles has motivated the research for safe and effective monitoring of large battery packs. This paper presents a unique sampling scheme for a delta sigma modulator that is independent of common mode voltage. The rejection of common mode voltage is important in the application of electric vehicles and other large battery packs in order to accurately measure every cell on the stack with varying common mode voltages. A switched capacitor implementation is the proposed solution, and simulations in Cadence provide the results. The simulations of the circuit supported the claim that it is independent...

  18. Theory and application of neural and graphical models in early cancer diagnostics

    Radhakrishnan, Adityanarayanan
    With the recent availability of large training datasets and graphics processing units (GPUs), we address challenges in the application of graphical models and neural networks to prediction sensitive areas such as healthcare. We begin by presenting our work in the context of learning graphical models from biological data. Namely, we present a combinatorial perspective of Markov Equivalence Classes (MECs), which defines the size of solution spaces when attempting to learn a graphical model from data. Through our analysis, we show that the size of these MECs can be exponential with respect to features of the graph (such as average degree)....

  19. Experimental implementations of stereo matching algorithms in Halide

    Zhang, Min, M. Eng. Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science (2016)
    Currently, most stereo matching algorithms focus their efforts on increasing accuracy at the price of losing run-time performance. However, applications such as robotics require high performance stereo algorithms to perform real time tasks. The problem is due to the difficulty of hand optimizing the complicated stereo matching pipelines. Halide is a programming language that has been widely used in writing high-performance image processing codes. In this work, we explore the usability of Halide in the area of real-time stereo algorithms by implementing several stereo algorithms in Halide. Because of Halide's ability to reduce the computation cost of dense algorithms, we...

  20. An Improved TaleBlazer Editor to encourage and facilitate collaboration between multiple TaleBlazer game designers

    Wang, Linda, M. Eng. Massachusetts Institute of Technology
    TaleBlazer is a platform for creating and playing educational location-based augmented reality games. These games are made by both adults and children game designers using the online TaleBlazer Editor. Oftentimes, building a TaleBlazer game is a group effort, but the previous Editor made collaboration inefficient, difficult, error-prone, and frustrating. This thesis describes a suite of features designed to improve version control for a game and assist designers in sharing their work with others. Together, these features encourage and facilitate collaboration between multiple TaleBlazer designers.

Aviso de cookies: Usamos cookies propias y de terceros para mejorar nuestros servicios, para análisis estadístico y para mostrarle publicidad. Si continua navegando consideramos que acepta su uso en los términos establecidos en la Política de cookies.