Página 4 dos resultados de 2122 itens digitais encontrados em 0.022 segundos
Resultados filtrados por Publicador: Massachusetts Institute of Technology

‣ Balancing capital and condition : an emerging approach to facility investment strategy

Wooldridge, Stephen C. (Stephen Craig), 1967-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 170 p.; 2263633 bytes; 2263386 bytes; application/pdf; application/pdf
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Capital facilities - land and buildings - provide a long-standing environment in which public and private enterprise works, communicates, and thrives. Aligning how facilities "fit" with the dynamic demands of enterprise necessitates continual investment in maintenance, modernization, and development. Conventional tools - condition assessment and master planning - provide a means for measuring this "fit" and producing related investment needs. These tools are often applied independently with a singular focus: condition assessment on physical systems and master planning on sizing and function. The resulting investment needs and condition metrics become fragmented elements of a larger (and often unstructured) investment context that must also consider funding realities and other strategic choices. Exceedingly the methods of collecting and managing assessment data are emphasized, while linkages to capital planning and decision-making remain narrowly focused and limited in scope. The result is simply greater volumes of more "bad news", as facility decision-makers are ill equipped to effectively synthesize numerous requirements and objectively understand the effects of investment decisions. This research develops and applies a new approach to facility investment strategy. The approach links the products of condition assessment and master planning...

‣ Opportunities created by information technology for the executive in the engineering and construction industry

Schwab, Olivier M. (Olivier Martin), 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 78 leaves; 5635334 bytes; 5635093 bytes; application/pdf; application/pdf
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by Olivier M. Schwab.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.; Includes bibliographical references (leaves 69-70).

‣ Information management in virtual engineering

Pasala, Jayaprakash, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 68 leaves; 4624121 bytes; 4623881 bytes; application/pdf; application/pdf
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by Jayaprakash Pasala.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999.; Includes bibliographical references (leaf 68).

‣ A web based integrated global project management system for large scale A/E/C/ projects; Web based integrated global project management system for large scale architecture, engineering and construction industry projects

Sutar, Ajit Kumar, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 85 leaves; 7150636 bytes; 7150393 bytes; application/pdf; application/pdf
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by Ajit Kumar Sutar.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.; Includes bibliographical references (leaves 79-81).

‣ VEI : an intelligent web collaboration system for virtual engineering; Intelligent agent and its application in remote sensors

Sun, Fuxin, 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 64 p.; 5222958 bytes; 5222719 bytes; application/pdf; application/pdf
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by Fuxin Sun.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.; Includes bibliographical references (p. [63]-64).

‣ Traffic engineering for hybrid optical and electronic switching networks

Rabbat, Richard R., 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 118 leaves; 8677623 bytes; 8677381 bytes; application/pdf; application/pdf
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by Richard Rizkallah Rabbat.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001.; Includes bibliographical references (leaves 115-118).

‣ Gravity, capillary and dilational wave mode resonance at a visco-elastic two-fluid interface

Brown, Susan Jayne, 1967-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 226 p.; 9624206 bytes; 9653374 bytes; application/pdf; application/pdf
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(cont.) space corresponding to experimental conditions to thereby interpret the experimental results. We tested this method on noisy simulated data sets and then applied it to published experimental data sets. We designed an experimental set-up to measure wave number, spatial damping coefficient, and wave slope data for a 3-10 hertz frequency range of transverse and longitudinal waves in a clean enclosed flume. We used kimball-mounted lasers whose beams passed through optical glass in the tank and lid to capture transverse wave motion. The experimental conditions included waves traveling on fatty acid monolayers on aqueous solutions and also waves traveling on a visco-elastic fluid at a variety of temperatures. In addition to the wave data we obtained, we also measured in-situ surface tension. Analyzing the experimental data, we demonstrated the effects of modulation of one wave mode on another. We obtained the rheological parameters for these experimental systems by the inverse method. We used the inverse method to construct the dispersion relation solution space corresponding to the experimental conditions. We used the diagnostic tools for root classification, spatial stability together with a graphical representation of the dispersion relation solution space to understand the physics underlying our experiments. We demonstrated resonance phenomena experimentally with the wave data from the visco-elastic fluid and confirmed this resonance numerically: gravity-capillary resonance near 4.2 hertz ...; This thesis is a study of first order resonance between gravity...

‣ An Internet based multimedia infrastructure for collaborative engineering

Vedam, Padmanabha N. (Padmanabha Naranjan), 1977-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 131 leaves; 10352181 bytes; 10351942 bytes; application/pdf; application/pdf
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by Padmanabha N. Vedam.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2000.; Includes bibliographical references (leaves 129-131).

‣ Effect of Web-based engineering information on asset management

Eckles, Thomas Austin, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 59 p.; 4579842 bytes; 4579647 bytes; application/pdf; application/pdf
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by Thomas Austin Eckles.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.; Includes bibliographical references (p. 59).

‣ Regional earthquake loss estimation : role of transportation network, sensitivity and uncertainty, and risk mitigation

Karaca, Erdem, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 292 p.; 19332248 bytes; 19371322 bytes; application/pdf; application/pdf
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Large earthquakes near densely populated areas such as the 1994 Northridge and 1995 Kobe events have caused extensive damage to the physical infrastructure and losses to the regional and national economies. Economic losses are due in part to direct damage and in part to business interruption caused by non- functioning infrastructure and interdependencies among industrial sectors. We developed a regional earthquake loss methodology that emphasizes economic interdependencies at regional and national scales and the mediating role of the transportation network. In an application to the Central U.S. under threat from earthquakes from the New Madrid Seismic Zone, we (1) evaluate regional and national losses from scenario earthquakes, (2) quantify uncertainty on the losses through loss risk curves including contributions from seismicity, attenuation, fragilities, etc. and (3) assess the effectiveness of alternative mitigation strategies. The loss assessment methodology includes spatial interactions (through the transportation network) and business interaction (through an input-output model) and extends geographically to the entire conterminous U.S. The losses reflect damage to buildings and transportation components, reduced functionality...

‣ Environmental liability, policy and technology in real estate development

Meherik, Deryk.
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 142 p.; 7847673 bytes; 7863861 bytes; application/pdf; application/pdf
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by Deryk Meherik.; Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.; Includes bibliographical references (p. 139-142).

‣ Seasonal dynamics in costal aquifers : investigation of submarine groundwater discharge through field measurements and numerical models; Investigation of SGD through field measurements and numerical models

Michael, Holly Anne, 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 186 p.; 22389920 bytes; 22870996 bytes; application/pdf; application/pdf
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The fresh and saline groundwater flowing from coastal aquifers into the ocean comprise submarine groundwater discharge (SGD). This outflow is an important pathway for the transport of nutrients and contaminants, and has been shown to adversely affect coastal ecosystems in many areas of the world. The focus of this work is the characterization of SGD and the mechanisms that drive it, with a specific emphasis on seasonal forcing. Field measurements during five summers in Waquoit Bay, Massachusetts reveal the pattern and composition of submarine groundwater discharge. Flow is highly variable over small spatial and temporal scales, and the salinity and radium content of the discharge demonstrates heterogeneity in groundwater origin. Maximum discharge occurred in two alongshore bands: brackish outflow nearshore and saline discharge offshore. Most of the total flow was saline, yet net seawater inflow over a tidal cycle was negligible. Circulation mechanisms such as tides, waves, and hydrodynamic dispersion cause significant saline groundwater discharge, and are potentially important for chemical loading to estuaries. However, these mechanisms can explain only 12-30% of the observed saline outflow in Waquoit Bay. A seasonal forcing mechanism is proposed to explain the source of the remaining observed saline outflow. During periods of high inland recharge...

‣ Household ceramic water filter evaluation using three simple low-cost methods : membrane filtration, 3M Petrifilm and hydrogen sulfide bacteria in northern region, Ghana

Mattelet, Claire (Claire Eliane H. Y.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 106 p.; 33104020 bytes; 33103590 bytes; application/pdf; application/pdf
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Drinking water continues to be a major source of waterborne diseases and death in the world because many points of water collection remain unsafe. This thesis reports high level of fecal contamination found in rivers and ponds that are major sources of drinking water supply for the local communities in and around Tamale, in the Northern region of Ghana. Although considerable improvements have been made in the past few decades, greater efforts are still needed to address key issues related to the supply of safe drinking water in Tamale. There is a need to make safe water available, accessible and affordable for the local communities. One such solution is household water treatment and safe storage HWTS), which is being promoted globally by the World Health Organization, international reference to promote household water treatment and safe storage. HWTS products are sold locally by Pure Home Water (PHW in Tamale. This work explores the microbial removal and flow rate performance of two of the PHW best sellers: the CT. Filtron and the Nnsupa filter. These two filters were compared with the Everest Aquaguard, the main competitor of PHW in Tamale. The CT.; (cont.) Filtron ceramic filter is the best performer in terms of flow rate efficiency...

‣ Modeling the fate and transport of nitrogen and sediment within coastal embayments on St. John, U.S. Virgin Islands

Walker, Jeffrey D. (Jeffrey Douglas)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 145 leaves
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The recent rises in resident and tourist populations on St. John in the U.S. Virgin Islands have spurred the construction of new roads and housing developments throughout much of the island. As a result, a number of pollutants, including sediment and nitrogen, are being delivered to the coastal waters around the island at increasing rates and are believed to be having adverse impacts on the health of coral reef ecosystems. Understanding the impacts of increased sediment and nitrogen loads on coral reefs is critical for the protection of these valuable natural resources. In the present study, two mass balance models for sediment and nitrogen were developed to evaluate the impact of watershed development on the water quality of coastal embayments. The sediment model considered inputs by watershed loading and losses by gravitational settling and tidal flushing. The degree of sediment stress inflicted upon each bay was evaluated using three stress metrics. The results of the sediment model agreed with historical turbidity measurements collected by the National Park Service in terms of the relative degree of sediment stress observed in each bay.; (cont.) A mass balance model for nitrogen was also developed accounting for input fluxes by groundwater discharge...

‣ Dynamic Planning and control Methodology : understanding and managing iterative error and change cycles in large-scale concurrent design and construction projects; Understanding and managing iterative error and change cycles in large-scale concurrent design and construction projects

Lee, Sang Hyun, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 2 v. (417 leaves)
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Construction projects are uncertain and complex in nature. One of the major driving forces that may account for these characteristics is iterative cycles caused by errors and changes. Errors and changes worsen project performance and consequently, cause schedule and cost overruns to be prevalent. In particular, these iterative cycles are more detrimental when large-scale concurrent design and construction is applied. In an effort to address these issues, this research proposes Dynamic Planning and control Methodology (DPM) as a robust design and construction planning methodology for large-scale concurrent design and construction. The proposed DPM is composed of: 1) an error and change management framework that enables understanding of the construction processes associated with errors and changes and how they affect construction performance; 2) a proactive buffering strategy for reducing sensitivity to iterative error and changes cycles; 3) a System Dynamics-based construction project model which provides policy guidelines for the planning and control of projects; and; (cont.) 4) a web-based error and change management system, which supports coordination of errors and changes among contractors and design professionals without hardware and software compatibility issues. Applying all research components into a couple of real world case projects...

‣ The accessibility and development impacts of new transit infrastructure : the Circle Line in Chicago

Warade, Ritesh K
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 242 p.
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This thesis explores the impacts of new transit infrastructure projects on the land use transportation system. Land use and transportation systems are inherently interconnected and form an integrated system; and transport projects affect not just the transportation system, but also land use patterns. Current evaluation frameworks and models applied to new transport infrastructure projects usually focus on transportation system improvements, and so do not reflect the process of land use transportation interaction. To overcome this limitation, this thesis argues that the evaluation of transport projects should consider their accessibility and development impacts; and that this requires models which explicitly incorporate the interaction between land use and transportation. The Circle Line in Chicago is a proposed circumferential rail transit line which will serve the urban core of the Chicago region, and is likely to significantly affect both land use and travel patterns.; (cont.) This thesis assesses how existing models can be used to quantify the accessibility and development impacts of this project; and how an existing evaluation framework, developed by the Federal Transit Administration, considers these impacts. In addition, this thesis develops a quasi-integrated land use transportation model for the Chicago region; and applies it to quantify the accessibility and development impacts of the Circle Line project. The frameworks and models developed for the Circle Line project provide an example of how to improve the current FTA evaluation methodology.; by Ritesh K. Warade.; Thesis (M.C.P.)--Massachusetts Institute of Technology...

‣ Momentum and mass transport by coherent structures in a shallow vegetated shear flow

White, Brian L., 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 231 p.
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In many aquatic systems, from tidal creeks with fringing mangroves to rivers and associated floodplains, there exists an interface between dense vegetation and a high conveyance channel. A shear flow develops across this interface and its dynamics influences the exchange of mass and momentum between the vegetation and the channel. This thesis describes an experimental study in a shallow laboratory channel with 1/3 of its width filled with circular cylinders, a model for emergent vegetation. The experiments reveal the formation of a shear layer with nearly periodic vortex structures. The vortices are documented with respect to their physical characteristics and their effect on mass and momentum exchange. Distributions of mean velocity and turbulent Reynolds stress show a two layer structure in the shear flow. An inner layer exists near the interface, with a width that establishes the penetration of momentum into the vegetation; an outer boundary layer exists in the main channel, where the vortices reside, with a width independent of the vegetation. In each layer the mean velocity distributions are self-similar. Results of a linear stability analysis suggest that channels with differential drag are conducive to the growth of Kelvin-Helmoltz shear instabilities. Indeed vortices are observed for all experimental conditions...

‣ Computational wind engineering using finite element package ADINA

Bajoria, Ankur
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 97 leaves
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Design of tall and long span structures is governed by the wind forces. Inadequate research in the field of wind dynamics has forced engineers to rely on design codes or wind tunnel tests for sufficient data. The present work uses a computational wind dynamics method to compare the coefficient of pressure (Cp) for the different aerodynamic shapes. ADINA, a finite element package, contains an inbuilt turbulence model which will be used to construct four different shapes for comparison. Results are verified with the experimental and simulation data. The effect of increase in the Reynolds number on the flow has been studied. Graphs for the pressure, velocity and turbulence energy distribution have been developed to assist the engineers in design.; by Ankur Bajoria.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2008.; Includes bibliographical references (leaves 61-64).

‣ Integrated Message Framework : strategy, design and implementation; IMF : strategy, design and implementation

Dajani, Tarek, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 94 leaves; 4154241 bytes; 4154049 bytes; application/pdf; application/pdf
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As we subscribe to more and more communication channels our 'world of messages' is becoming a complex matrix of dispersed information. Emailing, Blogging, Instant Messaging... have become customary daily activities for many. While the wealth of media enriches our interaction experiences, it nonetheless constrains our ability to assimilate information from one location (information is stored online, on a local machine, and on the local network) and in one format. As a matter of fact, given our reliance on multiple communication channels, we have to resort to using several distributed applications that lack a unified visual interface and storage structure. Result: 1- Incompatible message description and storage structures. 2- Incompatible message transfer and notification standards. As in the case of Email and Instant Messaging which despite their many similarities are still highly non interoperable. 3- No horizontal visibility across and within message media formats (Email, Blog, IM, etc...) preventing unified searches, correspondence logging and centralized information management. 4- Distributed contact and address repository, preventing access to a unified comprehensive 'Address Book'. Large corporations have the ability to resolve the issues above by forcing a top down standardization policy that regulates correspondence forms and formats between and across their business units. While that approach might prove fairly successful in homogeneous environments...

‣ Logistical and transportation infrastructure in Asia : potential for growth and development to support increasing trade with Europe

Deonás, Nikolaos, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 139 leaves; 8083907 bytes; 8083714 bytes; application/pdf; application/pdf
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This thesis examines the implications of the rapid growth in demand for trade between Europe and Asia for the existing transportation network and logistical infrastructure. In general terms, technologies need to improve and be compatible with each other, multimodalism and interconnectivity of the various modes needs to be fully implemented, capacities have to grow, facility efficiencies need to improve, planning processes, and government policies need to be updated, along with the growth of demand in the region. The nature and extent of the required changes depend on the role of each country in the region, as well as the capabilities and utilization of the existing infrastructure. The methodology involves an ABC analysis that groups the Asian countries in three categories depending on their level of development and infrastructure. The major transportation modes (urban, road, rail, sea, and air), the logistical infrastructure and the importance and use of Information Technology are examined. Leading economies of the region, categorized as "A" countries, appear to be very successful and are highly competitive in global trade. Network optimization and high technology applications, such as Intelligent Transportation Systems and Electronic Data Interchange can improve these countries' use of infrastructure. Developing countries of the region...