Página 10 dos resultados de 2122 itens digitais encontrados em 0.128 segundos

‣ Evaluation of coordinated and local ramp metering algorithm using microscopic traffic simulation

Scariza, Joseph R. (Joseph Ralph), 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 108 p.; 617418 bytes; 617173 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24046%
by Joseph R. Scariza.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.; Includes bibliographical references (p. 105-108).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Analyses and interpretation of tapered piezoprobe and application to offshore pile design

Sutabutr, Twarath
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 2 v. (462 leaves); 23884237 bytes; 23883994 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24046%
by Twarath Sutabutr.; Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.; Includes bibliographical references (v. 2, leaves 411-427).

‣ The chemistry of chlorine in combustion systems and the gas-phase formation of chlorinated and oxygenated pollutants

Procaccini, Carlo, 1965-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 140 leaves; 9919757 bytes; 9919514 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24046%
by Carlo Procaccini.; Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.; Includes bibliographical references.

‣ Improvements and reliability of MIT tensiometers and studies on soil moisture characteristic curves; Studies on soil moisture characteristic curves

Toker, Nabi Kartal, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 143 p.; 9923173 bytes; 9941972 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24046%
by Nabi Kartal Toker.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.; Includes bibliographical references (p. 141-143).

‣ Hydrologic and water quality modeling with HSPF : utilization of data from a novel field data collection system and historical archives; Hydrologic and water quality modeling with Hydrologic Simulation Program -- FORTRAN

Richards, Kevin Tarn, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 95 leaves; 4313153 bytes; 4324106 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24046%
by Kevin Tarn Richards.; Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.; Includes bibliographical references (leaf 63).

‣ Design and evaluation of AMPER : a probabilistic routing protocol for mobile ad hoc networks; Ad hoc, Modular, Probabilistic, Enhanced Routing

Jabbour, Abdallah W. (Abdallah Wahib), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 91 p.; 2984266 bytes; 2984067 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24046%
An ad hoc network is a group of mobile nodes that autonomously establish connectivity via multi-hop wireless links, without relying on any pre-configured network infrastructure. Traditional ad hoc routing protocols use a large number of routing packets to adapt to network changes, thereby reducing the amount of bandwidth left to carry data. Moreover, they route data packets along a single path from source to destination, which introduces considerable latency for recovery from a link failure along this path. Finally, they often use the minimum hop count as a basis for routing, which does not always guarantee a high throughput. This thesis presents AMPER (Ad hoc, Modular, Probabilistic, Enhanced Routing), an ad hoc routing protocol that minimizes the routing packet overhead, allows the use of alternate paths in the event of a link outage, and employs - without loss of generality - the expected number of transmissions to make forwarding decisions. Following the design of AMPER, ns-2 is used to simulate it, evaluate it and compare it to other ad hoc routing protocols.; by Abdallah W. Jabbour.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.; Includes bibliographical references (p. 89-91).

‣ Speeding up solar disinfection : effects of hydrogen peroxide, temperature, and copper plus ascorbate on the photoinactivation of E. coli in Charles River water

Fisher, Michael Benjamin, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 136 p.; 6291212 bytes; 6309002 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24648%
Sunlight efficiently disinfects drinking water in plastic bottles over two days, but simple additives may show promise for reducing this time to several hours. This study found that adding up to 500 [micro]M hydrogen peroxide accelerates the room-temperature inactivation of E. coli K12 by sunlight at a rate proportional to concentration, while temperatures of 35 and 45 degrees Celsius further enhance this effect. It was also found that both 25 [micro]M ascorbic acid in the presence of 2.5 [micro]M copper sulfate and solid copper metal in the presence of 200 [micro]M ascorbate synergistically increased the light-mediated inactivation rate with first-order dependence in both dissolved species, while the addition of hydrogen peroxide to this system exhibited further synergistic enhancement. Although solid copper and 1% lemon juice performed no better than lemon juice alone, the latter significantly accelerated inactivation in a light-dependent manner. Finally, at higher concentrations the copper-ascorbate system can also inactivate E. coli in the dark. These findings suggest possible directions for accelerating the rate of SODIS, with potential for the Cu + ascorbate system to act as a residual disinfectant and an alternative to SODIS on extremely cloudy days.; by Michael Benjamin Fisher.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ An investigation of the principles and practices of seismic isolation in bridge structures

Lapointe, Evan M. (Evan McNeil), 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 79 leaves; 2989313 bytes; 2989122 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24648%
Within the past decade, seismic isolation systems have gained rapid popularity in the earthquake resistant design of bridge structures. This popularity has come in response to the inadequacy of earlier seismic design and retrofit methodologies. The mechanical shortcomings and subsequent failure mechanisms associated with the early elastic seismic design philosophy are first presented, followed by a study of the applicability of seismic isolation systems in bridge structures. This investigation includes a discussion of the susceptibility of simple span bridges to seismic failure, an overview of the behavior of base isolated structures, a detailed description of isolation system components, an explanation of the mechanics of elastometric isolation bearings, and a presentation of the linear theory of seismic isolation. The qualitative investigation of seismic isolation systems is supplemented by a quantitative nonlinear time-history analysis that illustrates the response of a simple span bridge to seismic excitation. The analysis examines the effects of the varying stiffness of a lead-rubber elastometric bearing upon structural response when subjected to the 1940 El Centro earthquake. The results confirm the expected behavior of isolated structures and emphasize the need for site-specific studies in the design of effective seismic isolation systems for bridge structures.; by Evan M. Lapointe.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ Automatic classification of documents with an in-depth analysis of information extraction and automatic summarization

Hohm, Joseph Brandon, 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 92 leaves; 3024644 bytes; 3024453 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.2486%
Today, annual information fabrication per capita exceeds two hundred and fifty megabytes. As the amount of data increases, classification and retrieval methods become more necessary to find relevant information. This thesis describes a .Net application (named I-Document) that establishes an automatic classification scheme in a peer-to-peer environment that allows free sharing of academic, business, and personal documents. A Web service architecture for metadata extraction, Information Extraction, Information Retrieval, and text summarization is depicted. Specific details regarding the coding process, competition, business model, and technology employed in the project are also discussed.; by Joseph Brandon Hohm.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2004.; Includes bibliographical references (leaves 78-80).

‣ The World Trade Center disaster : Analysis and recommendations

Kirk, Jeremy Abraham, 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 43 p.; 2917220 bytes; 2920158 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24384%
The terrorist attacks of September 11, 2001 brought about the destruction of two symbols of American economic strength, the twin towers of the World Trade Center in New York City. These towers remained standing for some time after the initial aircraft impact, allowing many occupants to escape, but eventually collapsed to the ground. Much research has been done to determine the precise mechanisms of collapse, but there is not yet a consensus. This thesis explores and summarizes the leading theories to date, with particular emphasis on the ongoing research by the National Institute of Standards and Technology (NIST). Several ideas for improving building performance and for preventing progressive collapse are also presented.; by Jeremy Abraham Kirk.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.; Includes bibliographical references (p. 42-43).

‣ Experimental investigation and constitutive modeling of metallic honeycombs in sandwich structures

Mohr, Dirk, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 226 p.; 11640341 bytes; 11640148 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.2486%
Traditionally, honeycomb sandwich structures are designed in the elastic range, but recent studies on the crushing of sandwich profiles have shown their potential in crashworthiness applications. Thin sandwich sheets also hold a promise for widespread use in automotive industry because standard sheet metal forming technology could be used to produce double-curvature sandwich shell structures. The crashworthiness and formability of sandwich structures are critically dependent on the behavior of the sandwich core under large plastic deformation. In this thesis, a new biaxial testing device has been developed for the reliable characterization of the mechanical behavior of cellular materials. Using this device, the macroscopic phenomenology and the underlying microstructural deformation mechanisms of thin-walled aluminum honeycomb have been studied experimentally for combined out-of-plane shear and normal loading. Furthermore, numerical simulations of the experiments have been performed where the cell walls of the specimen microstructure have been discretized with fine shell element meshes. Based on the experimental and numerical results, a finite-strain rate-independent orthotropic constitutive model for metallic honeycombs has been formulated and implemented into commercial finite element software. The good agreement of the model predictions with the experimental results encourages the use of this constitutive model for applications involving large plastic out-of-plane deformation. On the structural scale...

‣ Vibration analysis and control of dynamics effects of moving vehicles over bridges

Medina Andrés, Violeta
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 56 leaves; 1817544 bytes; 1819793 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24648%
An extensive review and evaluation of the optimal models to asses the dynamic effects of moving vehicle on a bridge is performed. These models, with increasing grades of complexity, represent the best approximation of the problem under certain assumptions. Case studies are also performed with these models. In addition to the dynamic analyses, which allow evaluations of the problem and gives valuable hints on the optimal design of bridges subjected to moving vehicles, vibration control devices such Tuned Mass Dampers (TMD) and Multiple Tuned Mass Damper (MTMD) are presented. Results from different authors are included, which allow assessing the applicability and effectiveness of these methods.; by Violeta Medina Andrés.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.; Includes bibliographical references (leaf 53).

‣ Isolation and characterization of bacterial polyhydroxybutyrate inclusions

Kshetry, Nina
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 83 leaves; 22238044 bytes; 22237606 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.24648%
Polyhydroxybutyrate (PHB) is a carbon reserve found in some bacteria, and under nutrient limiting conditions accumulates intracellularly in the form of inclusion bodies. These inclusions contain proteins, and the PHB within the inclusions exists in an amorphous state. In this study a procedure to recover native PHB inclusions was developed, and the isolated inclusions were characterized using 13C NMR, western blotting, SDS-PAGE, atomic force microscopy, and fluorescence microscopy. A model for the structure of native PHB inclusions is proposed.; by Nina Kshetry.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2006.; Includes bibliographical references (leaves 79-83).

‣ Power generation from geothermal resources : challenges and opportunities

Kitsou, Olga, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 79 leaves
Português
Relevância na Pesquisa
138.24384%
by Olga Kitsou.; Thesis (S.M.)--Massachusetts Institute of Technology, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.; Includes bibliographical references (leaves 73-79).

‣ Nonlinear diffraction and refraction of regular and random waves

Chen, Meng-Yi
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 306 p.
Português
Relevância na Pesquisa
138.24384%
The mild-slope equation is an effective approximation for treating the combined effects of refraction and diffraction of infinitesimal water waves, for it reduces the spatial dimension of the linear boundary value problem from three to two. We extend this approximation to nonlinear waves up to the second order in wave steepness, in order to simplify the inherently three-dimensional task. Assuming that the geometrical complexity is restricted to a finite, though large, horizontal domain, the hybrid-element method designed earlier for linearized problems is modified for the two-dimensional elliptic boundary-value problems at the second order. This thesis consists of two parts. In Part I, the incident waves are monochromatic. Application is first made to the special case of a a semi-circular peninsula (or a vertical cylinder on a cliff). Effects of the angle of incidence are examined for the free surface height along the cylinder. Numerical results for three examples involving radially varying depth are discussed. In Part II the second-order mild-slope approximation will be further extended for random waves with a broad frequency spectrum. A stochastic approach of Sclavounos is generalized for the prediction of spectral response in harbors. Focuss is on the low-frequency harbor resonance...

‣ Seismic design of a current woodframe structure and study of innovative products and damping systems in wood construction; Study of innovative products and damping systems in wood construction

Mahjoub, Nina A. (Nina Azadeh)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 97 p.
Português
Relevância na Pesquisa
138.2486%
Wood structures have seen resurgence in popularity over the past several decades, especially in Western States of America, such as California. The industry keeps creating new structural wood products of exceptional strength, versatility, and reliability. Woodframe structures offer a more sustainable answer, but need to be carefully detailed in high seismic zone. The objective of this work is to describe the seismic design of a current woodframe structure. Moreover, this thesis aims to present the innovation occurring in the market of wood construction. New engineered wood products are introduced as well as a review of the new developments and researches that are being made to incorporate damping systems such as viscoelastic and hysteretic dampers, in the ultimate goal of obtaining an optimum earthquake-resistant wood structure.; by Nina A. Mahjoub.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.; Includes bibliographical references (p. 96-97).

‣ Household-level point-of-use water filtration system in Haiti : strategies for program management and sustainability

Mohamed, Farzana S., 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 33 p.
Português
Relevância na Pesquisa
138.24648%
by Farzana S. Mohamed.; Thesis (M.C.P.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.; Includes bibliographical references (p. 30-33).

‣ Bayesian expert systems and multi-agent modeling for learner-centric Web-based education

Rabbat, Ralph R., 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 150 leaves; 7062661 bytes; 7083067 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.2486%
Online distance education provides students with a wealth of information. When students submit course-related search term queries, the search engine returns the search hits based on keyword and topic match. A student's particular learning style is not taken into consideration. For instance, a visually oriented student may benefit more than others from viewing videos and interacting with simulations. We address this problem by designing and developing a knowledge-based system for the initial assessment of students' learning styles. Each student's membership in a learning style dimension (e.g. visual or verbal) is estimated probabilistically. We reach this probability value by using a sequential Bayesian approach to administer a dynamic questionnaire that aims to attain a desired confidence level estimate with the minimal number of questions. A multi-agent online tutoring system uses this initial learning style model to start suggesting learning material matching the student's style. Each agent is an expert in a learning style dimension and can suggest the learning materials matching the student's style. In addition, these agents closely follow the student's evolving preferences and continuously update the stochastic model based on the student's online activities. When the student searches for course material...

‣ Optimizing and verifying an ensemble-based rainfall model

Friedman, Sara Hargrove
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 64 p.
Português
Relevância na Pesquisa
138.24648%
In this thesis, I modified, optimized, and verified the stochastic Recursive Cluster-point Rainfall model of Chatdarong (2006). A novel error metric allows comparison of the stochastic ensemble of rainfall image forecasts to a single observation (radar) image. The error metric forgives position errors and provides a flexible framework for assessing how well the model works vis-a-vis a set of image measures, including the distribution of rainfall intensities over the domain at different scales. The error metric is used in various forms to perform ad hoc optimization of the model parameters and to verify the ensemble forecast in a probabilistic framework. Verification results show that the optimized model is limited in its ability to create truly realistic rainfall patterns. Despite the model's limitations, it has unique applicability to ensemble-based rainfall data assimilation.; by Sara Hargrove Friedman.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.; Includes bibliographical references (p. 63-64).

‣ Parallel implementations of dynamic traffic assignment models and algorithms for dynamic shortest path problems

Jiang, Hai, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 144 p.; 6560942 bytes; 6560745 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.2486%
This thesis aims at the development of faster Dynamic Traffic Assignment (DTA) models to meet the computational efficiency required by real world applications. A DTA model can be decomposed into several sub-models, of which the most time consuming ones are the dynamic network loading model and the user's route choice model. We apply parallel computing technology to the dynamic network loading model to achieve faster implementations. To the best of our knowledge, this concerns the first parallel implementations of macroscopic DTA models. Two loading algorithms are studied: the iterative loading algorithm and the chronological loading algorithm. For the iterative loading algorithm, two parallelization strategies are implemented: decomposition by network topology and by time. For the chronological loading algorithm, the network topology decomposition strategy is implemented. Computational tests are carried out in a distributed-memory environment. Satisfactory speedups are achieved. We design efficient shortest path algorithms to speedup the user's route choice model. We first present a framework for static shortest path algorithms, which prioritize nodes with optimal distance labels in the scan eligible list. Then we apply the framework in dynamic FIFO...