Página 12 dos resultados de 100905 itens digitais encontrados em 0.164 segundos

‣ Design and editing 2.5-dimensional terrain in StarLogo TNG; Design and editing two point five dimensional terrain in StarLogo The Next Generation

Wendel, Daniel J
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 69 leaves
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StarLogo TNG is "The Next Generation" in block-based decentralized programming for modeling and simulation software. Its aim is to make computer programming more appealing for students in middle school and high school. Part of the draw of StarLogo TNG is its 3-D rendered world called Spaceland where "agents" live on a terrain made of a grid of "patches". This thesis evaluates and outlines the redesign of Spaceland and its associated terrain editor based on user-task analysis, and discusses the design of new data structures to support the desired features.; by Daniel J. Wendel.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.; Includes bibliographical references (leaf 60).

‣ Tracking dynamic regions of texture and shape

Migdal, Joshua N. (Joshua Nicholas), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 142 p.
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The tracking of visual phenomena is a problem of fundamental importance in computer vision. Tracks are used in many contexts, including object recognition, classification, camera calibration, and scene understanding. However, the use of such data is limited by the types of objects we are able to track and the environments in which we can track them. Objects whose shape or appearance can change in complex ways are difficult to track as it is difficult to represent or predict the appearance of such objects. Furthermore, other elements of the scene may interact with the tracked object, changing its appearance, or hiding part or all of it from view. In this thesis, we address the problem of tracking deformable, dynamically textured regions under challenging conditions involving visual clutter, distractions, and multiple and prolonged occlusion. We introduce a model of appearance capable of compactly representing regions undergoing nonuniform, nonrepeating changes to both its textured appearance and shape. We describe methods of maintaining such a model and show how it enables efficient and effective occlusion reasoning. By treating the visual appearance as a dynamically changing textured region, we show how such a model enables the tracking of groups of people. By tracking groups of people instead of each individual independently...

‣ Emulation of microprocessor memory systems using the RAMP design framework

Khan, Asif I. (Asif Imtiaz)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 50 leaves
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With the computer hardware industry and the academic world focused on multiprocessor systems, the RAMP project is aiming to provide the infrastructure for supporting high-speed emulation of large scale, massively-parallel multiprocessor systems using FPGAs. The RAMP design framework provides the platform for building this infrastructure. This research utilizes this design framework to emulate various microprocessor memory systems through a model built in an FPGA. We model both the latency and the bandwidth of memory systems through a parameterized emulation platform, thereby, demonstrating the validity of the design framework. We also show the efficiency of the framework through an evaluation of the utilized FPGA resources.; by Asif I. Khan.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.; Includes bibliographical references (p. 49-50).

‣ Approximate inference in Gaussian graphical models

Malioutov, Dmitry M., 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 169 p.
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The focus of this thesis is approximate inference in Gaussian graphical models. A graphical model is a family of probability distributions in which the structure of interactions among the random variables is captured by a graph. Graphical models have become a powerful tool to describe complex high-dimensional systems specified through local interactions. While such models are extremely rich and can represent a diverse range of phenomena, inference in general graphical models is a hard problem. In this thesis we study Gaussian graphical models, in which the joint distribution of all the random variables is Gaussian, and the graphical structure is exposed in the inverse of the covariance matrix. Such models are commonly used in a variety of fields, including remote sensing, computer vision, biology and sensor networks. Inference in Gaussian models reduces to matrix inversion, but for very large-scale models and for models requiring distributed inference, matrix inversion is not feasible. We first study a representation of inference in Gaussian graphical models in terms of computing sums of weights of walks in the graph -- where means, variances and correlations can be represented as such walk-sums. This representation holds in a wide class of Gaussian models that we call walk-summable. We develop a walk-sum interpretation for a popular distributed approximate inference algorithm called loopy belief propagation (LBP)...

‣ Interfaces for creating quantitative conceptual diagrams

Stewart, Robin S. (Robin Scott)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 73 p.
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Modern chart-making, illustration, and mathematical tools poorly support the use of conceptual components in quantitative graphs such as Economics diagrams. The substantial time those tools require to achieve the desired results leads many people to sketch their graphs with pencil and paper instead of using a computer. In this thesis, I address the challenge of designing a software user interface that not only includes all features necessary to create a wide range of quantitative conceptual diagrams, but also is dramatically more efficient to use than existing programs. My design takes several important interaction techniques that previous applications used separately and comprehensively integrates them in order to create new, flexible capabilities. I have implemented this design as a desktop application called Graph Sketcher, and I present results of studies which show that my interface halves the time required to complete several common graph creation tasks. I also show that the 700 students, teachers, professionals, and hobbyists worldwide who choose to use Graph Sketcher in their everyday work nd the interface intuitive, enjoyable, and empowering for generating many different types of graphs.; by Robin S. Stewart.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Camera-microcomputer interface

Graham, Helen Louise
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 135 [i.e. 136] leaves
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by Helen Louise Graham.; Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1980.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Includes bibliographcial references.

‣ Efficient object recognition and image retrieval for large-scale applications

Lee, John Jaesung
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 93 p.
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Algorithms for recognition and retrieval tasks generally call for both speed and accuracy. When scaling up to very large applications, however, we encounter additional significant requirements: adaptability and scalability. In many real-world systems, large numbers of images are constantly added to the database, requiring the algorithm to quickly tune itself to recent trends so it can serve queries more effectively. Moreover, the systems need to be able to meet the demands of simultaneous queries from many users. In this thesis, I describe two new algorithms intended to meet these requirements and give an extensive experimental evaluation for both. The first algorithm constructs an adaptive vocabulary forest, which is an efficient image-database model that grows and shrinks as needed while adapting its structure to tune itself to recent trends. The second algorithm is a method for efficiently performing classification tasks by comparing query images to only a fixed number of training examples, regardless of the size of the image database. These two methods can be combined to create a fast, adaptable, and scalable vision system suitable for large-scale applications. I also introduce LIBPMK, a fast implementation of common computer vision processing pipelines such as that of the pyramid match kernel. This implementation was used to build several successful interactive applications as well as batch experiments for research settings. This implementation...

‣ Design of an instrumented multifunctional foot for application to a heavy duty mobile robot manufacturing system

Menon, Manas Chandran
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 57 p.
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The design of a multifunctional foot for application to a mobile robotic system for heavy duty manufacturing is presented. The requirements for a target manufacturing task are presented and translated into requirements for the mobile robotic system, and specifically for the feet of this system. This includes: the ability of the feet to change frictional properties, the ability of the foot to operate without a direct power source, and load bearing requirements for heavy duty tooling. The mechanical design to meet these requirements for these feet is presented. Stability analysis is shown, and it is used to determine several design parameters to meet the goals of the project. The development of a series of iterations of prototypes is discussed. Manufacturing techniques, choice of materials, alignment strategies and assembly practices are explained. Appendices include information about several of the important design milestones. A sensing methodology is introduced. Computer simulations of magnetic fields to estimate the effectiveness of this methodology are performed. Experimental results are shown to match the simulations. A final functional prototype is shown. Testing is performed on this prototype to verify that it meets the functional requirements desired for the system.; by Manas Chandran Menon.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ A real time autonomous underwater vehicle Dynamic Simulator

Jurewicz, Thomas A.
Fonte: Monterey, California: Naval Postgraduate School Publicador: Monterey, California: Naval Postgraduate School
Tipo: Tese de Doutorado Formato: viii, 82 p. ill.
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Approved for public release; distribution is unlimited.; The NPS Autonomous Underwater Vehicle Simulator is a joint project between the Naval Postgraduate School's Mechanical Engineering and Computer Science Departments. In order to test mission planning and execution software, an accurate vehicle dynamic model is required. Using dynamics based upon the Navy's Swimmer Delivery Vehicle (SDV), there is a need to continually update the hydrodynamic coefficients based upon actual vehicle-in-water testing. The NPS AUV Dynamic Simulator contains a full set of submarine equations of motion and hydrodynamic coefficients. The coefficients are modifiable on-line, and a replay capability exists for further performance review. Using Monterey Bay as an underwater testing environment, there is need to be able to display expansive terrain data while maintaining the real time simulation. The Variable Terrain Resolution Algorithm incorporated into the NPS AUV Dynamic Simulator enables the entire Monterey Bay data base to be displayed in real time. Resolution adjustments are made automatically based upon the vehicle's depth level and system performance.; Commander, United States Navy

‣ Computer-aided course enrollment system for Computer Science Curriculum Office

Ertugrul, Erkan
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 208 p.
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The major problem addressed in this study is to automate the Course Enrollment Process in Computer Science Curriculum Office thus to reduce the time spent in this process and increase the reliability and efficiency of the current system. The approach taken was to do a requirement analysis design an automated system by using Yourdon's Structured Analysis Method and implement the design in C++ programming language. The resulting program that we wrote enables the curriculum staff to keep information about students, courses and tracks, and generate the enrollment list and send messages to the students. It also enables the students to prepare their matrices, sign up for courses, get course and track information and send messages to the curricular officer through the application. The curriculum staff has reviewed the program and thought that it could be used in the real-world environment. But, it was not put into service in the curriculum. A future study can install the program to the computers in the office and test how effective the program is.; NA; NA; Turkish Army author.

‣ Sound-induced micromechanical motions in an isolated cochlea preparation

Page, Scott Lawrence
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 57 p.
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The mechanical processes at work within the organ of Corti can be greatly elucidated by measuring both radial motions and traveling-wave behavior of structures within this organ in response to sound stimuli. To enable such measurements, we have developed a new preparation for observing three-dimensional motions of micromechanical structures in the apical region of an isolated gerbil cochlea. The cochlea is submerged in a low-chloride, low-calcium artificial perilymph solution and cemented to the bottom of a Petri dish at an angle. The bone above scala vestibuli of one half of the apical turn is removed to allow optical imaging with a 40x, 0.8 NA water-immersion objective. Reissner's membrane is left intact. Illumination is provided with a blue LED coupled to an optical fiber. The fiber is positioned next to the bone surrounding scala tympani of the apical turn, so that the organ of Corti is illuminated from below. The resulting optical access allows imaging of a variety of structures that have been proposed to play a role in cochlear mechanics, including inner and outer hair cell bundles, the tectorial membrane, inner and outer pillar cells, and efferent fibers in the tunnel of Corti. In some preparations, individual stereocilia of inner hair cell bundles can be resolved.; (cont.) Motions are stimulated by driving the stapes with a piezoelectric probe...

‣ Recognition of hand drawn chemical diagrams; Understanding hand drawn chemical structures : segmentation and recognition of handwriting and sketching in freehand diagrams

Ouyang, Tom Yu
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 52 p.
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Chemists often use hand-drawn structural diagrams to capture and communicate ideas about organic compounds. However, the software available today for specifying these structures to a computer relies on a traditional mouse and keyboard interface, and as a result lacks the ease of use, naturalness, and speed of drawing on paper. In response, we have developed a novel sketch-based system capable of interpreting hand-drawn organic chemistry diagrams, allowing users to draw molecules with a penbased input device in much the same way that they would on paper. The system's ability to interpret a sketch is based on knowledge about both chemistry and chemical drawing conventions. The system employs a trainable symbol recognizer incorporating both feature-based and image-based methods to locate and identify symbols in the sketch. Analysis of the spatial context around each symbol allows the system to choose among competing interpretations and determine an initial structure for the molecule. Finally, knowledge of chemistry (in particular atomic valence) enables the system to check the validity of its interpretation and, when necessary, refine it to recover from inconsistencies. We demonstrate that the system is capable of recognizing diagrams of common organic molecules and show that using domain knowledge produces a noticeable improvement in recognition accuracy.; by Tom Yu Ouyang.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Distributed algorithms for self-disassembly in modular robots

Gilpin, Kyle W
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 226 p.
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We developed a modular robotic system that behaves as programmable matter. Specifically, we designed, implemented, and tested a collection of robots that, starting from an amorphous arrangement, can be assembled into arbitrary shapes and then commanded to self-disassemble in an organized manner. The 28 modules in the system were implemented as 1.77-inch autonomous cubes that were able to connect to and communicate with their immediate neighbors. Two cooperating microprocessors controlled the modules' magnetic connection mechanisms and infrared communication interfaces. We developed algorithms for the distributed communication and control of the system which allowed the modules to perform localization and distribute shape information in an efficient manner. When assembled into a structure, the modules formed a system which could be virtually sculpted using a computer interface which we also designed. By employing the sculpting process, we were able to accurately control the final shape assumed by the structure. Unnecessary modules disconnected from the structure and fell away. The results of close to 200 experiments showed the that the algorithms operated as expected and were able to successfully control the distributed system. We were able to quickly form one...

‣ FireViz : a personal firewall visualizing tool; FireViz : a personal network firewall visualizing tool

Sharma, Nidhi
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 95 p.; 4618721 bytes; 4622665 bytes; application/pdf; application/pdf
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In this thesis, I present FireViz, a personal firewall visualizing tool. FireViz visually displays activities of a personal firewall in real time. The primary goal of FireViz is to educate typical computer users of the security threats their computers are exposed to when connected to a network and expose any potential loop holes in the firewall's security policies. To this end, FireViz presents a novel visualization paradigm that provides users with an informative yet non-intrusive interface to their network and firewall. FireViz achieves this by incorporating a peripheral mapping of the network on the user's screen and displaying network events along this periphery. Information about network events is encoded visually to help users develop a more intuitive model of the network at a low cost. The peripheral nature of FireViz along with the use of non-modal visual displays allows users to easily understand network events without obstructing their primary tasks. The visualization is also capable of highlighting exceptional events that may represent potential threats without relying on the end user to understand ally threat model. Thus, FireViz aims to provide users with a superior framework for understanding the network security model and achieving improved system security in the process.; by Nidhi Sharma.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ MIT Device Simulation WebLab : an online simulator for microelectronic devices; WeblabSim

Solis, Adrian (Adrian Orbita)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 157 p.; 7134632 bytes; 7141207 bytes; application/pdf; application/pdf
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In the field of microelectronics, a device simulator is an important engineering tool with tremendous educational value. With a device simulator, a student can examine the characteristics of a microelectronic device described by a particular model. This makes it easier to develop an intuition for the general behavior of that device and examine the impact of particular device parameters on device characteristics. In this thesis, we designed and implemented the MIT Device Simulation WebLab ("WeblabSim"), an online simulator for exploring the behavior of microelectronic devices. WeblabSim makes a device simulator readily available to users on the web anywhere, and at any time. Through a Java applet interface, a user connected to the Internet specifies and submits a simulation to the system. A program performs the simulation on a computer that can be located anywhere else on the Internet. The results are then sent back to the user's applet for graphing and further analysis. The WeblabSim system uses a three-tier design based on the iLab Batched Experiment Architecture. It consists of a client applet that lets users configure simulations, a laboratory server that runs them, and a generic service broker that mediates between the two through SOAP-based web services. We have implemented a graphical client applet...

‣ A Raw processor interface to an 802.11b/g RF front end

Walker, Benjamin Philip Eugene Zaks
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 96 p.; 3892796 bytes; 3896740 bytes; application/pdf; application/pdf
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The Raw microprocessor is a tiled architecture processor designed by the Computer Architecture Group at MIT. Raw was designed in part to be extremely good at performing streaming-type algorithms such as those found in wireless communications processing. This thesis describes the design and implementation of an interface between the Raw microprocessor and a modified 802.11a/b/g wireless access point. Combined with the Raw processor, this interface replaces a custom digital chip in the access point. The interface can be used with the Raw microprocessor to perform communications research, and as a system demonstrating Raw's capabilities. The interface has been built, tested, and functionally qualified.; by Benjamin Philip Eugene Zaks Walker.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2004.; Includes bibliographical references (p. 95-96).

‣ Dr. Jones : a software design explorer's crystal ball; Software design explorer's crystal ball

Foltz, Mark A. (Mark Alan), 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 154 p.
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Most of software design is redesign. Redesign in the normal course of design happens when the software becomes difficult to maintain and the problem it is intended to solve has changed. Although software redesign is necessary, frequent, and pervasive, there is a dearth of tools that help programmers do it. Instead, programmers primarily use pen and paper, away from the computer where tools could help the most. To address this shortcoming, I have developed DR. JONES, a redesign assistant for Java programs. DR. JONES diagrams the class structure of a Java program and allows the programmer to modify that design by applying refactorings. Refactorings are localized patterns of structural change intended to improve a program's design, without changing its observable behavior. With DR. JONES, the programmer can explore the design space of the program, inspect future designs as visual diagrams, and get design assistance to guide his refactoring choices. As the programmer explores designs, DR. JONES explicitly maps the design space he traverses. This map lets him revisit any prior design and branch to explore an alternative design path, without having to explicitly manage versions of the program. DR. JONES is distinguished from other refactoring tools by separating the tasks of developing an improved design through design exploration from transforming the source code to execute design changes. It does so by deriving and using an abstract representation of the program that captures the essential information needed for design exploration...

‣ Computational geometry through the information lens

Pătrașcu, Mihai
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 117 p.
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This thesis revisits classic problems in computational geometry from the modern algorithmic perspective of exploiting the bounded precision of the input. In one dimension, this viewpoint has taken over as the standard model of computation, and has led to a powerful suite of techniques that constitute a mature field of research. In two or more dimensions, we have seen great success in understanding orthogonal problems, which decompose naturally into one dimensional problems. However, problems of a nonorthogonal nature, the core of computational geometry, have remained uncracked for many years despite extensive effort. For example, Willard asked in SODA'92 for a o(nlg n) algorithm for Voronoi diagrams. Despite growing interest in the problem, it was not successfully solved until this thesis. Formally, let w be the number of bits in a computer word, and consider n points with O(w)-bit rational coordinates. This thesis describes: * a data structure for 2-d point location with O(n) space, and 0( ... )query time. * randomized algorithms with running time 9 ... ) for 3-d convex hull, 2-d Voronoi diagram, 2-d line segment intersection, and a variety of related problems. * a data structure for 2-d dynamic convex hull, with O ( ... )query time...

‣ Distributed routing

O'Leary, Art
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 85 leaves; 3916032 bytes; 3915790 bytes; application/pdf; application/pdf
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by Art O'Leary.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1981.; MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.; Bibliography: leaf 85.

‣ Drift compensated inertial position sensor for healthcare patient monitoring

Nelson, David Lee, M. Eng. Massachusetts Institute of Technology
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 72 p.
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In order to provide more effective health care, especially to the elderly, we must enable the physician to monitor the patient outside of the clinic or hospital. A patient's activities are a critical indicator of his or her well-being, and the physician must have an un-intrusive and inexpensive means of monitoring patient activity. The objective of this project was to design and construct a low-cost, low-power, six degree-of-freedom inertial activity monitor that can be used with a portable computer. In this thesis, I describe the design and implementation of a such a monitor that can communicate using several popular peripheral bus protocols. I describe a simple attitude estimation filter and give a qualitative assessment of its performance.; by David Lee Nelson.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2005.; Includes bibliographical references (p. 71-72).