Página 3 dos resultados de 2122 itens digitais encontrados em 0.022 segundos
Resultados filtrados por Publicador: Massachusetts Institute of Technology

‣ Experimental and theoretical modeling of DNAPL transport in vertical fractured media; Experimental and theoretical modeling of dense, non-aqueous phase liquids transport in vertical fractured media

Levy, Laurent Claude, 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 2 v. (614 p.); 6654704 bytes; 6654459 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.33061%
In recent years, groundwater contamination by dense, non-aqueous phase liquids (DNAPLs) such as chlorinated solvents and polychlorinated biphenyls (PCBs) has become an important environmental concern in many industrialized areas. Accidental spills, poor storage facilities and inadequate disposal practices are factors contributing to the release of these chemicals into the subsurface environment. The detection and presence of DNAPLs at hazardous waste sites is likely to be a significant limiting factor in the site remediation process. This is especially true for the remediation of complex subsurface formations, such as fractured bedrock. This work has developed a new model describing DNAPL infiltration into a water- saturated, vertical fracture idealized as a circular section capillary tube. A series of laboratory and geotechnical centrifuge experiments of DNAPL infiltration into vertical capillary tubes was performed to demonstrate the validity of the model, and examine the role played by capillary, gravity, viscous, and inertia forces during the infiltration process. The new model can be used to better understand the processes likely to influence DNAPL transport and remediation in real fracture systems.; (cont.) Laboratory infiltration experiments showed that the common assumption of perfect wetting at the DNAPL/water interface is incorrect. Furthermore...

‣ The Hawaii carbon dioxide ocean sequestration field experiment : a case study in public perceptions and institutional effectiveness

De Figueiredo, Mark A. (Mark Anthony), 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 239 p.; 1298766 bytes; 1298521 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32671%
by Mark Anthony de Figueiredo.; Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.; Includes bibliographical references.; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ The role of public-private clean diesel R&D partnerships in the regulatory process; Role of public-private clean diesel research and development partnerships in the regulatory process

Ng, Christine Bik-Kay, 1979-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 181 p.; 636665 bytes; 672276 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32883%
by Christine Bik-Kay Ng.; Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.; Includes bibliographical references (p. 163-180).; This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.

‣ Benefits of emerging transportation technologies : simulation analysis and policy issues

Cortes, Margaret T. (Margaret Therese), 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 98 p.; 7067278 bytes; 7067041 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32671%
by Margaret T. Cortes.; Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M. in Transportation)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2003.; Includes bibliographical references (p. 96-98).

‣ Patterns of shallow clouds and rainfall over the Amazon : climatic impacts of deforestation

Chagnon, Frédéric J. F. (Frédéric Jacques F.), 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 440 p.; 26253289 bytes; 26314381 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32645%
(cont.) and, to a lesser extent, cold cloud patterns over the Amazon. Through complex interactions, the results reported in this thesis may have important implications for the local ecosystem dynamics of the Amazon, for the geomorphology of the Amazon river basin, for the flow regimes of the Amazon river, and for global climate.; The climatic impact of the current state of deforestation in the Amazon basin is examined in this thesis. Past modeling studies have shown that complete deforestation of the Amazon basin could result in dramatic decreases in regional rainfall and evaporation leading to desertification (e. g., Salati and Vose [1984], Shukla et al. [1990]). Yet, although 15% of the 4,000,000 km² Brazilian Amazon has already been deforested [INPE, 2003], current deforestation patterns in the Amazon basin are not uniform, nor do their extents surpass tens of kilometers. Numerical simulations indicate that idealized heterogeneities of land-surface properties could lead to organized mesoscale circulations that enhance convection (e. g., Anthes [1984], Chen and Avissar [1994a], Avissar and Liu [1996], Wang et al. [1998]); similar results were found in case-study simulations of actual Amazon deforestation (e. g., Wang et al. [2000]...

‣ Development and implementation of a combined discrete and finite element multibody dynamics simulation environment

Komodromos, Petros I. (Petros Ioannis)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 200, [1] p.; 11144320 bytes; 11170425 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.33203%
Some engineering applications and physical phenomena involve multiple bodies that undergo large displacements involving collisions between the bodies. Considering the difficulties and cost associated when conducting physical experiments of such systems, there is a demand for numerical simulation capabilities. The discrete element methods (DEM) are numerical techniques that have been specifically developed to facilitate simulations of distinct bodies that interact with each other through contact forces. In DEM the simulated bodies are typically assumed to be infinitely rigid. However, there are multibody systems for which it is useful to take into account the deformability of the simulated bodies. The objective of this research is to incorporate deformability in DEM, enabling the evaluation of the stress and strain distributions within simulated bodies during simulation. In order to achieve this goal, an Updated Lagrangian (UL) Finite Element (FE) formulation and an explicit time integration scheme have been employed together with some simplifiying assumptions to linearize this highly nonlinear contact problem and obtain solutions with realistic computational cost. An object-oriented extendable computational tool has been built specifically to allow us to simulate multiple distinct bodies that interact through contact forces allowing selected bodies to be deformable. Database technology has also been utilized in order to efficiently handle the huge amounts of computed results.; by Petros Komodromos.; Thesis (Ph. D.)--Massachusetts Institute of Technology...

‣ Modeling and analysis of phosphorus reduction by rain gardens and other BMPs in stormwater runoff from small urban developments

Obeid, Najwa, 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 72 leaves; 4033044 bytes; 4040333 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32883%
As part of The Discovery Museums (TDM) Low Impact Development (LID) Design and Monitoring report (Master of Engineering Group Project) for the town of Acton, , the effectiveness of low impact development technologies at improving the quality of stormwater runoff from TDMs parking lot was evaluated. Several Best Management Practices (BMPs) and LID technologies were assessed to determine which devices would be most suitable for the site. The P8 Urban Catchment Model was chosen to model phosphorus concentrations in stormwater runoff before and after the implementation of LID. The results were then assessed to determine whether or not these technologies significantly improve the runoff water quality. In this thesis, the analysis is extended to assess the improvement in phosphorus concentrations if rain gardens are implemented on a fraction of residential areas in the Nashoba Brook watershed. The effectiveness of a rain garden at improving the phosphorus concentrations in runoff was evaluated by modeling the device in P8. Both the TDM site analysis and the Nashoba Brook hypothetical analysis yielded results with significant reduction in total phosphorus loading. These results should encourage further research on the widespread use of LID.; by Najwa Obeid.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ Numerical upper and lower bound limit analysis for braced excavations

Degwitz, Fernando G. (Fernando Guillermo), 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 79 leaves; 2744763 bytes; 2744570 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32883%
This thesis reviews limit theorems and their applications for stability problems in geotechnical engineering. Rigorous numerical solutions of limit analyses can be obtained through finite element discretization of the soil mass and formulation of the limit theorems within a linear programming framework. The current research uses a formulation proposed by Sloan et al. (1988) and extended in a recent Ph.D. thesis by Ukritchon (1998) to include soil-structure interactions. The thesis details the input and output required for numerical limit analysis and presents an example application for the stability of a broad excavation for the MUNI Metro Turnback project in San Francisco. This well documented case study involves a 13 M deep excavation within a deep deposit of May Mud that was supported by an SPTC wall with three levels of cross-lot bracing. The numerical limit analyses calculate factors of safety, FS = 1.03 - 1.36, against basal instability. The factor of safety used in the original design (FS = 1.2) is contained in this range. The results illustrate that numerical limit analysis offers a practical alternative to limit equilibrium methods in evaluating the stability of braced excavations.; by Fernando G. Degwitz.; Thesis (M. Eng.)--Massachusetts Institute of Technology...

‣ Comparative analysis of energy consumption trends in cohousing and alternate housing arrangements

Brown, Jason R. (Jason Robert), 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 92 p.; 3151151 bytes; 3150960 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32889%
The sizes of both single-family and multifamily homes have grown steadily in the United States over the last fifty years. During this time, despite more efficient production processes, energy consumption in the country also rose. The many concerns associated with increased energy consumption include hastening depletion of fossil fuel resources, increased dependence on foreign resources for fuel, environmental concerns related to fossil fuel emissions, and ensuring all people have access to economic energy sources. Awareness of the necessity to engage in more sustainable practices (environmentally, economically, and socially) has existed at least since the 1960s. The United Nations formalized these concerns in the 1987 publication, "Our Common Future" in which they defined and popularized the term "sustainable development." Despite this awareness and the continuing efforts of governmental and non-governmental agencies to reduce the impact of energy consumption, the rate of consumption has continued to rise and the rate of growth of energy consumption has only seen marginal improvements in the United States (and has risen dramatically in some developing countries such as China and India).; (cont.) One way to reduce the rate of consumption or slow the rate of growth is to reduce the impact of the United States housing market through demand management techniques and energy efficient construction. Cohousing offers one opportunity to accomplish that goal. This thesis outlines the background information related to U.S. energy consumption and housing trends...

‣ Prediction of early-age cracking of UHPC materials and structures : a thremo-chemo-mechanics approach

Shim, JongMin, 1975-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 159, [13] p.; 7805482 bytes; 7826831 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.33058%
Ultra-High Performance Concrete [UHPC] has remarkable performance in mechanical properties, ductility, economical benefit, etc., but early-age cracking of UHPC can become an issue during the manufacturing process due to the high cement content and the highly exothermic hydration reaction. Because of the risk of early-age UHPC cracking, there is a need to develop a material model that captures the behavior of UHPC at early-ages. The objective of this research is to develop a new material model for early-age UHPC through a thermodynamics approach. The new model is a two-phase thermo-chemo-mechanical model, which is based on two pillars: the first is a hardened two-phase UHPC material model, and the second is a hydration kinetics model for ordinary concrete. The coupling of these two models is achieved by considering the evolution of the strength and stiffness properties in the two-phase UHPC material model in function of the hydration degree. The efficiency of the model and finite element implementation is validated with experimental data obtained during the casting of a DuctalTM optimized bridge girder. Based on some decoupling hypothesis, the application of the early-age UHPC model can be carried out in a two-step manner: the thermo-chemical problem is solved first...

‣ Development of software architecture for environmental monitoring using wireless sensor networks

Hari, Piyush
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 63 leaves; 18187306 bytes; 18186972 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32414%
In this thesis, I describe the development of the software architecture for temperature monitoring using Wireless Sensor Networks (WSN). The goal of the software is to provide a means to remotely monitor and analyze temperature data in a closed environment. This architecture forms a building block to achieve the larger aim of energy management in built facilities. A 16 node wireless sensor network was set up to monitor ambient temperature at various locations in MIT. A console application was developed in the C# language to collect temporal sensor data and store it in a SQL database. The application also provides a management system for fire hazard warnings by sending e-mails and calling mobile phones. An ASP.NET web application is then developed to retrieve temperature data over Internet. The data is accessible in different formats-table, XML and visualized in graphical form. This application lets the user register their phone numbers and e-mails to be informed in case of a fire emergency or excessive heating/cooling. A mobile application is developed on top of the web application to increase the range of data access to handheld Internet enabled telephony devices such as mobile phones and PDAs.; (cont.) The web access is implemented in XHTML-MP with a .NET web service and J2EE web service client back end. A desktop application is then used to access the real time temperature data through a PC desktop connected to the Internet. Spatial representation of data is visualized by overlaying the temperature profiles with floor plans and maps of the buildings using GIS.; by Piyush Hari.; Thesis (S.M.)--Massachusetts Institute of Technology...

‣ Invariant mechanical properties of calcium-silicate-hydrates (C-H-S) in cement-based materials : instrumented nanoindentation and microporomechanical modeling

Constantinides, Georgios, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 507 p.
Português
Relevância na Pesquisa
138.33107%
Random porous solids such as bone and geomaterials exhibit a multiphase composite nature, characterized by water-filled pores of nm- to m-scale diameter. The natural synthesis and operating environments of such materials significantly alters phase composition and multiscale structural heterogeneities throughout the material lifetime, defining significant changes in macroscopic mechanical performance for applications ranging from multispan bridges to calcium-phosphate bone replacement cements. However, the nanoscale phases formed within the unique chemical environment of pores cannot be recapitulated ex situ in bulk form, and imaging of the composite microstructure is obfuscated by the size, environmental fragility, and nonconductive nature of such geomaterials and natural composites. Thus, there is an increasing drive to develop new approaches to image, quantify the mechanical contributions of, and understand the chemomechanical coupling of distinct phases in such composites. In this thesis, we utilize recent advances in experimentation namely instrumented indentation, and micromechanical modeling namely homogenization techniques, in an attempt to quantify the mutli-phase, multi-scale heterogeneity observed in all cement-based materials. We report a systematic framework for mechanically enabled imaging...

‣ The design and analysis of tension fabric structures

Son, Miriam Euni
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 48 leaves
Português
Relevância na Pesquisa
138.32406%
Although tensioned fabric structures are increasingly in demand, since they are comparatively new to the engineering world, there are relatively limited resources available about such structures. This report reviews the topics that encompass the design and analysis of tensioned fabric structures. First, an overview of the conceptual basis of tensioned membranes is discussed, as well as the different shapes that are formed using manipulations of the basic concept. Since the material properties play a key role in the durability of tension fabric structures, the ideal material characteristics, as well as the current available fabrics are described. Both the strength of the employed materials and the load considerations for design are outlined. The report follows by explaining the process of roughly assessing the scope of a project, as well as the variety of non-linear analysis that must be performed and the methods used to perform them. This report concludes with key connection details that must be considered for a successful tension fabric structure.; by Miriam Euni Son.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.; Includes bibliographical references (leaf 48).

‣ Momentum and scalar transport in vegetated shear flows

Ghisalberti, Marco (Marco Andrea), 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 119 p.
Português
Relevância na Pesquisa
138.32414%
Environmental aquatic flows are seldom free of vegetative influence. However, the impact of submerged vegetation on the hydrodynamics and mixing processes in aquatic flows remains poorly understood. In this thesis, I present the results of laboratory experiments that describe the salient hydrodynamic and transport features of vegetated flows. Flume experiments were conducted with dowels and buoyant polyethylene strips used to mimic rigid canopies and flexible seagrass meadows respectively. Although traditionally treated as rough boundary layers, vegetated shear flows more closely resemble mixing layers. Specifically, vertical velocity profiles contain an inflection point, yielding the flow unstable to a street of Kelvin-Helmholtz vortices. These vortices dominate transport through the shear layer, such that the rate of mixing of both mass and momentum is shown to scale upon their size and rotational speed. However, mass is mixed approximately twice as rapidly as momentum. The spread of a scalar plume is shown to be a function of the number of vortex cycles experienced by the plume, irrespective of the canopy characteristics or flow speed. In contrast to mixing layers, the vortices in a vegetated shear layer grow only to a finite size...

‣ Crack coalescence in molded gypsum and Carrara marble

Wong, Ngai Yuen
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 2 v. (876 p.)
Português
Relevância na Pesquisa
138.33107%
This thesis investigates the fracturing and coalescence behavior in prismatic laboratory molded gypsum and Carrara marble specimens, which consist of either one or two preexisting open flaws, under uniaxial compression. In previous experimental studies, the determination of crack types (shear/tensile) was mainly based on the identification of fractographical features on the crack surfaces. In the present study, a high speed video system was used, which allowed one to precisely observe the cracking mechanisms.Seven crack types, which were characterized by different nature (shear/tensile) and orientations were identified to initiate from the pre-existing flaws in gypsum and marble in the present experimental study. Nine crack coalescence categories with different crack types and trajectories were also identified. The flaw inclination angle (beta), the ligament length (L), i.e. intact rock length between the flaws, and the bridging angle (a), i.e. the inclination of a line linking up the inner flaw tips, between two flaws, have all shown to have different effects on the coalescence patterns. Comparing the fracturing and coalescence behaviors in the two tested materials, tensile fracturing generally occurs more often in marble than in gypsum for the same flaw pair geometries.One of the pronounced differences observed between marble and gypsum during the compression loading test was the development of macroscopic white patches prior to the initiation of macroscopic cracks in marble...

‣ Structure and dynamics of genome-wide diversity in Prochlorococcus

Coleman, Maureen Lynn
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 285 p.
Português
Relevância na Pesquisa
138.32817%
The capability of microbes to thrive in myriad environments has its foundation in the diversity of microbial genomes. Here we explore adaptation and diversification through the lens of the marine cyanobacterium Prochlorococcus, which comprises a group of closely-related ecotypes that together perform most of the primary production in low-nutrient regions of the world oceans. Prochlorococcus was one of the first microbes in which a genomic basis for ecological differentiation was characterized, in the distinction between high- and low-light adapted ecotypes. It is clear, however, that other axes of differentiation are important, including temperature, nutrient availability, and biotic interactions. This thesis seeks to characterize salient aspects of genomic diversity in Prochlorococcus and to advance understanding of the ecological and evolutionary forces that shape this variation. We show that closely related isolates harbor remarkably dissimilar gene complements, and much of this variation is concentrated in specific genome regions, termed islands, that appear to have arisen through phage-mediated gene transfer. Several island-encoded genes likely play important metabolic roles, as inferred from their strong and specific upregulation under stress conditions. A region of the genome involved in phosphate assimilation has highly variable gene content that appears to reflect oceanic phosphate availability. Accordingly...

‣ Geomorphology and ecohydrology of water-limited ecosystems : a modeling approach

Collins, Daniel B. G. (Daniel Benjamin Gardiner), 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 129 p.
Português
Relevância na Pesquisa
138.32817%
The role of vegetation in shaping landforms and how these landforms respond to disturbances are the subjects of this work. A numerical model is developed to help develop a mechanistic understanding of the hydrological, ecological and geomorphic interactions in water-limited ecosystems. The growth of vegetation suppresses increases in runoff, thus reducing erosion efficiency and increasing topographic slopes as rainfall increases in dry climates. Moving along a climatic gradient to wetter climates leads to the point where the effect of vegetation is overwhelmed by increasing runoff, thus erosion efficiency increases and slopes decrease. This transition in vegetation controls translates into a minimum in drainage density for a semi-arid climate. Erosion efficiency is also affected by down-slope increases in vegetation, fostered by subsurface flow, an effect that reduces channel concavity. Plant characteristics also play a role in erosion by changing the variability of the vegetative effects. Comparing regions with the same fractional vegetation cover, those with faster growing or deeper rooted plants have greater erosion efficiencies.; (cont.) The landforms' responses to disturbances depend largely on the recovery time, which in turn depends on the climate and successional characteristics of the vegetation. The erosional response to sustained changes in mean annual rainfall depends on the magnitude and direction of the change as well as on the mean rainfall prior to the change. This means that landscapes most sensitive to erosion differ depending on whether rainfall increases or decreases. Hence...

‣ Polyethylene devices and the effects of sediment resuspension on the cycling of PAHs and PCBs in the lower Hudson Estuary

Adams, Rachel G. (Rachel Gwen), 1972-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 184 p.; 7965390 bytes; 13735532 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.33149%
In order to examine the importance of sediment resuspension on the sediment bed-to-water column transport of hydrophobic organic contaminants (HOCs) in the lower Hudson Estuary, the following areas of research were pursued: 1) a passive, in situ sampler, a polyethylene device (PED), for measuring HOCs in the aquatic environment was developed; 2) the desorption rate of pyrene, a polycyclic aromatic hydrocarbon (PAH), from native Hudson River sediments was measured, and 3) pyrene and 2,2',5,5'-tetrachlorobiphenyl (PCB #52), a polychlorinated biphenyl (PCB), concentrations were measured in the lower Hudson Estuary so that the input of these chemicals as a result of sediment resuspension could be compared to modeling expectations and the contribution of sediment resuspension to these chemicals' cycling could be quantified. The use of a new passive, in situ sampler, a polyethylene device (PED), for measuring hydrophobic organic contaminants (HOCs) in the aquatic environment was demonstrated. Like semipermeable membrane devices (SPMDs) and solid-phase microextraction (SPME), PEDs passively measure the concentration of chemical present in the dissolved phase. PEDs provide for in situ, time-averaged measurements with fast equilibration times (on the order of days) and simple laboratory extraction. Polyethylene-water equilibrium partitioning constants (KpEws) and polyethylene diffusivity coefficients (DPEs) were measured in the laboratory so that dissolved concentrations could be calculated subsequent to PED extraction.; (cont.) KPEWs for eleven PAHs and PCBs were found to correlate closely with octanol-water equilibrium partitioning constants (Kows; log KPEW = 1.1 log Kow-0.45...

‣ Strategic indicators for characterization of water system infrastructure and management

Garvin, Michael J. (Michael Joseph)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 203 p.; 17270903 bytes; 17270662 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.32889%
Shifts in the US water industry are characteristic of the flux found across all infrastructure sectors. Economic, environmental, market, regulatory and systemic forces are pushing the industry toward a different future where challenges of significant capital formation, competitiveness, efficiency and resource allocation will be prevalent. Amidst these drivers, longstanding assumptions about water provision and management are under scrutiny. The path forward remains unsettled as industry players debate the role of the federal government in financing pending capital challenges. The two sides of the debate describe divergent paths, and the one taken will define the industry's near-term structure. One hand indicates a pending crisis that necessitates substantial federal assistance while the other suggests staying the course towards self-sufficiency.; (cont.) Missing from these discussions is objective evidence concerning the state of the industry. To supply the missing component, this thesis develops and applies a rational methodology to characterize a national cross section of large water systems. The methodology provides a basis for (a) understanding the state of systems within the national portfolio and (b) guiding strategic assessment and policy development. A set of common...

‣ Megacities : sustainability, transport, and economic development

Tobias, Justin Charles, 1980-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 160 p.; 10430725 bytes; 10452879 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
138.3301%
The connections between sustainability, transport, and economic development are and will remain essential in the governance of cities. Sustainability concepts include valuing and preserving the earth's resources so that future generations can enjoy their benefits. It requires changing human behavior and practices to be more efficient and less damaging to the environment, especially with the current rates of population growth and urban concentration. In addition, there is the element of social equity in which investments should secure benefits for all classes of society, not just the affluent. These concepts are particularly applicable in transportation systems, because they have been neglected in the traditional quantitative approaches to planning and investment. Of course, policies defining transportation and those enacted for sustainability impact economic development, which is a chief priority of governments. Therefore, future success in urban areas lies in balancing an array of interests and adopting the most comprehensively advantageous policies. This study will demonstrate the need for rethinking traditional urban transportation development strategies. It will detail the problems associated with urban transport that infringe on environmental conditions and human quality of life. This paper will explain approaches to transportation that can lead to improvements in the negative corollaries currently experienced. It will also present policy measures and tools that can be implemented. This research paper will provide information for city officials and planners to better understand the implications of transportation policies and the options available for governance.; (cont.) These decisions are becoming more critical as urban growth leads to large metropolitan regions with incredible transportation demands. More optimistically...