Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references. / Three forces drive the information economy: competition, customers, and change. Supply chain integration seeks to achieve optimal performance of the supply chain as a whole by finding the appropriate balance of "focused" excellence and process coordination. Successfully overcoming the corporate silos of the industrial age requires a focus on process, systems integration, and supply chain collaboration. New models of electronic commerce were often not economically feasible before the widespread deployment of the internet, but they fundamentally rely on the same principles of marketing and supply chain integration that govern the pre-internet business world. Intelligent agents, real-time personalized marketing, and online catalogs all rely on a solid relational database model. These business models have been successfully measured by analyzing their impact on Return on Assets and cost reduction. Recent implementations of technology such as the Extensible Markup Language (XML) hold much promise. Using XML as a communication standard, and with a strong process focus, the RosettaNet organization and other leading companies arc demonstrating that the key clements of a successful business model in an internet economy are process-oriented supply chain integration and customer-focused electronic commerce. / by Jason B. Slibeck. / M.Eng.

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 103-106). / This thesis summarizes the history of lunar soil exploration through the Surveyor and Apollo programs, 1966 - 1972. Our current knowledge of the physical and engineering properties of the lunar regolith is derived mainly from measurements made on bulk and core samples returned to earth, as well as trenching, penetration and simple geophysical experiments performed during the five successful Apollo missions to the moon. Most of this data corresponds to material in the upper 1 to 3 m of the lunar surface. Lunar regolith is comprised of a mixture of basalt, impact melt glasses, breccias and agglutinate particles, and is derived from processes related to surface impacts and volcanic activity. The soil itself has a particle size distribution that resembles a well graded silty sand with angular particles and often containing a significant fraction of crushable (hollow) glass spheroids and agglutinates. The soil typically has a specific gravity of 3.1 and is found at an average porosity of approximately 45 - 50 %. The material has both cohesive and frictional components of shear strength, the former presumed to be related to electro-static forces between particles. Recent Space Exploration Initiatives have motivated the development of simulants that replicate quite closely the average properties of lunar regolith. These materials provide the basis for future lunar and Martian exploration and construction priorities. / by Javen S. Figueroa. / M.Eng.

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (p. 48-52). / The Republic of Cyprus is currently suffering from severe drought conditions. This is not uncommon to Cyprus, as they frequently experience three to four year droughts every decade. They are currently in the middle of their fourth year of drought. Some Cypriots believe that the main reason for water shortages is due only to low levels of rainfall (average rainfall in Cyprus is 500 mm per year, and less than 400 mm per year is considered a drought year). It is not disputed that this is part of the problem. However, my belief, along with many Cypriots is that the biggest part of the problem is one of water allocation. Agriculture in Cyprus contributes approximately 5% to the GDP, yet consumes 75% of available water in Cyprus. The remainder of water is left for the sector of the economy that produces the remaining 95% of the GDP, of which municipal, industrial and tourist uses are of greatest importance. One may ask why this is so. According to some Cypriots, it is because Cypriot farmers are thought to be a politically influential group, and that they farm more as a way of life, rather than to earn a living directly. Others discount this "way of life" theory. What is important, however is that farming is using a lot of water and is contributing very little to the GDP of Cyprus. For example, Citrus crops grown within the Southern Conveyor System (a large network of water conveyance pipes stretching for over 100 km in the southern part of the island) (see Figure 3, page 16) uses approximately 21% of all available water available in Cyprus, and without Government subsidies would not show profitability. Although there may be some aesthetic value in citrus groves one must ask if it is economically and environmentally justified to continue farming citrus. To do so means building seawater desalination plants that contribute 5.0 to 6.0 kg of CO 2, a greenhouse gas, to the atmosphere per m3 of water produced by desalination, along with the cost of the water nearing one US dollar per m3 . Desalination is a painful solution to Cyprus' water shortage that could be otherwise be addressed with a proper water allocation scheme. / by Mark P. Batho. / M.Eng.

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 68-69). / Waste stabilization ponds are reviewed as a means to treat wastewater. Processes involved in the three main types of waste stabilization ponds are also reviewed. Empirically derived design guidelines are used to propose a design for a series of lagoons to follow a chemically enhanced primary treatment stage in the city of Tatui, Brazil. An existing dynamic "bio-geo-chemical" waste stabilization pond model is reviewed and modified. The modified model is used to fit data from the anaerobic lagoon of a wastewater treatment facility in Riviera de Sao Lorenco. The model is also fit onto aerated lagoon data from the As-Samra treatment station in Amman, Jordan. Both models fit the data well, characterizing pond behavior satisfactorily. The models are then used to predict effluent quality for two different designs for the treatment of wastewater in Tatui. The model for the aerated lagoon is showed to be insufficient, due to the lack of appropriate data. Recommendations are proposed to improve the model with the available data. The anaerobic/facultative pond model, when used in the predictive mode, prompted a redesign of the proposed anaerobic lagoon for Tatui. / by Frédéric Chagnon. / M.Eng.

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 1999. / Includes bibliographical references (leaves 94-97). / Many companies see how new strategies and technologies can enable more efficient and adaptive supply chains-but they struggle to understand how these technologies overlay with existing processes and personnel issues both during and after implementation. This thesis investigates the concept of a simulated environment where multiple constituents whether they are different parts of a company's organization or different companies within a supply chain-can come together to design and experiment with new supply chain structures. The thesis explores the argument that the supply chain can be simulated, and evaluates different approaches to developing such a simulation that would allow low-risk experimentation and accelerated learning for supply chain managers. The thesis begins with an executive summary that provides a high level treatment of the challenges and recommendations associated with supply chain simulation, then proceeds to present a definition of the elaborate interrelationships between companies, technologies and business processes that collectively shape an industry's supply chain. This is followed by a discussion of complexity theory and general simulation techniques that could be applicable to the development of a software simulation environment in this area. Then, a review of efforts to date to simulate management of the supply chain, including approach, resources required, and eventual results is followed by a recommendation and justification of the thesis' approach to supply chain simulation. Finally, operating methods are presented for development and management of the learning and decision-making processes required to best utilize the software. The conclusion of the thesis is that because of the emergence of new technologies, the supply chain can be simulated for practical experimentation and learning. It is apparent that significant supply chain performance improvement can be identified and quantified through simulation. The thesis recommends using agent-based modeling, specifically a software package called Swarm, as the software environment. The software should be supported by operating methods that can maximize its capabilities while encouraging the likelihood of adoption of solutions identified. / by Christopher Michael Taylor Holt. / M.Eng.

Thesis: Ph. D. in Transportation, Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2018 / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 145-158). / This thesis develops a new model of the energy requirements of personal vehicle travel and uses it to evaluate tools to decarbonize the transport sector. Energy use and carbon emissions from transportation are spread across millions of miles of roadways and hundreds of millions of travelers. This diversity of travel patterns makes it challenging to catalogue and predict those quantities and difficult to characterize the mechanisms that drive them. However, a better understanding of transport energy use patterns is needed to find options for reducing personal vehicle energy requirements and greenhouse gas emissions. Existing research on transportation and climate policy often represents energy use in a fundamentally simplified manner. Some research does not account for the effect of usage patterns on technology performance, missing variation in technology impacts across context of use. / Other research informs technology modeling with a simplified picture of travel patterns, missing contexts in which technologies will be used. The research in this thesis adds new insight by assessing technology performance based on a comprehensive picture of travel patterns. This better captures both how travel patterns determine technology performance and how technology performance constrains achievable transformations to the transport sector. It combines high-resolution driving data with comprehensive travel patterns from household travel surveys or a transport network simulation, integrating data at multiple scales to avoid simplifications that mask relationships between technology use, technology performance, and systemwide carbon intensity. The central finding of this thesis is that retaining heterogeneity in travel behavior and technology performance allows us to better understand barriers to and strategies for transport decarbonization that will be missed with simpler methods. / Specifically, this thesis addresses electric vehicle range limitations, finding that they provide a constraint on transport electrification that is relatively limited and consistent across locations. This research also reveals interactions between electric vehicle charging and the electricity grid and uncovers how to better align electricity demand and supply under high solar photovoltaics penetration. This understanding will help inform targeted technological development and policies as well as help identify risks and unintended consequences in a transition to a low-carbon transportation system. / by Zachary A. Needell. / Ph. D. in Transportation / Ph.D.inTransportation Massachusetts Institute of Technology, Department of Civil and Environmental Engineering

Thesis: S.M., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019 / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 44-46). / This thesis addresses current shortcomings in the post-disaster housing response from a structural engineering perspective, proposing a new methodology to approach a multi-design standardized solution. Known environmental loading taken from building codes is analyzed over the entire United States to create a data-set that describes the distinct loading conditions of each region. Loads are clustered into grouping that suggest a single housing typology could address the structural need of the group. Additional non-structural data is added in consideration of performance-driven design metrics that are not structural by nature. To prove viability of the methodology, a case study was implemented to propose a structural design for a selected cluster of regions. Performance-based design was implemented through parametric modeling tools considering multiple objectives including structural weight, transportation logistics, interior thermal comfort, and off-grid utilities. The exercise demonstrated that the cluster analysis serves as a practicable tool for intelligently informed standardized housing design. / by Courtney P. Stephen. / S.M. / S.M. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019 / Cataloged from student-submitted PDF version of thesis. / Includes bibliographical references (pages 237-251). / Quantifying chemical fluxes between natural waters and their benthic sediments is a central problem in biogeochemistry, yet it is notoriously challenging. A relatively new method for measuring benthic fluxes, Eddy Correlation (EC) addresses many shortcomings of traditional techniques. Minimally invasive and measured in situ, EC is based on high-speed, simultaneous, and co-located velocity and concentration measurements. It has been successfully used in a range of settings to determine benthic fluxes of dissolved oxygen, using an Acoustic Doppler Velocimeter (ADV) to measure water velocity and an oxygen microelectrode to measure concentration. Widespread application to a larger range of compounds is limited, however, by the lack of chemical sensors that are fast, small, and sensitive enough for EC. To address this need, a novel trimodal sensor has been developed that is capable of high-speed, high-resolution measurements of fluorescence, temperature, and conductivity. / The core of the instrument is an optical fiber spectrofluorometer, which utilizes an LED for low-cost excitation; pair of 1000 [mu]m optical fibers for minimal disruption to velocity measurements; a tunable monochromator to enable a wide range of detection wavelengths; and a custom photon counting detector for maximum sensitivity. It can be used in an EC system to measure benthic fluxes of fluorescing compounds, such as fluorescent dissolved organic material. A fast thermistor and conductivity cell are also located at the tips of the optical fibers, enabling heat and salinity flux measurements that can be used as tracers for submarine groundwater discharge. Additionally, the ability to measure three simultaneous fluxes enables exploration of the potential to use the measured flux of one compound to infer another. Such 'flux tracing' would vastly expand the range of chemicals measurable with EC. / After development and testing of the individual sensors, the ability of the instrument to take three simultaneous, co-located measurements was demonstrated in a flume: under turbulent flow, the three sensors were able to detect similar features from an injection of warm, salty, fluorescent dye. The instrument was then coupled to an ADV for flux measurements, and tested in a specially constructed laboratory tank whereby benthic fluxes were released at known rates from the tank floor. The fluxes measured by all three sensors compared favorably with expected values. In addition, fluxes measured by the three sensors were observed to track each other, demonstrating the viability of flux tracing in settings with co-transported compounds. / by Irene Helen Hu. / Ph. D. / Ph.D. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019 / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 118-125). / Estimates suggest that the world needs a 50% increase in food production to meet the demands of the 2050 global population (Tilman et. al. 2011). Cropland expansion is unlikely to be sufficient, and yield improvements that require more inputs may lead to more environmental damage. This work focuses on reallocating limited land and water resources to optimize cropping patterns. By combining optimization methods, surrogate modeling, global data sources, data assimilation, and hydrologic modeling, we identify opportunities for increasing food-crop production and cash-crop revenue, while maintaining sustainability constraints that limit cropland expansion and prevent groundwater depletion. We apply the framework in India's Krishna river basin and find that reallocating resources to meet or exceed current production can lead to 96% gain in net revenue as resources over an estimated current baseline. Resources in this case are moved to high-yielding cash crops. Imposing a self-sufficient southern diet which depends on rice reduces the gains to 77% while imposing a self-sufficient national diet with more emphasis on wheat eliminates all net revenue gains to the region. The approach described in this thesis, highlights the trade-offs between food production, cost and environmental impacts in achieving specified food-security objectives. This research contributes to the field in two ways: 1) it provides a novel method for combining remotely sensed data, surrogate models and optimization to understand agricultural trade-offs, and 2) it furthers the discussion on food and water security and sustainable resource management by demonstrating that resource reallocation with sustainability constraints provides revenue gains in certain situations. / by Anjuli Jain Figueroa. / Ph. D. / Ph.D. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2019 / Cataloged from PDF version of thesis. / Includes bibliographical references. / Submerged outfalls consisting of multiple, closely spaced jets are often used to discharge industrial effluents in coastal waterbodies. Examples of such effluents include heated water from thermal power plants, treated wastewater effluent from sewage treatment plants, and reject brine from desalination plants. At locations with shallow water depth, the interaction between adjacent jets is enhanced and can affect mixing. The mixing of submerged outfalls in shallow water is studied in this thesis with particular emphasis on discharge of dense treated brine from desalination plants. Treatment options for brine involve blending it with less saline effluents or its concentration, and can have significant effect on the design of outfall and its mixing. The effect of shallow water depth on dilution of submerged outfalls is determined first for quiescent conditions, and a unified theory is developed for single and multiple jets discharging in shallow water. / The effect of shallowness is shown to be characterized by a non-dimensional parameter, which depends on the receiving water depth and the effluent momentum and buoyancy fluxes. The effect of brine treatment processes, which affect both discharge momentum and buoyancy, on the dilution of various contaminants is determined next. The effect of brine treatment on outfall design is also explored, and optimum outfall design variables are calculated for a range of conditions. In the presence of a crossflow, the mixing dynamics of multiple port outfalls are quite different, and can give rise to complex jet interactions and even reversing flow close to the upstream jets. Laboratory experiments, in which discharge and ambient parameters are varied, have led to an improved empirical expression for dilution. In addition to the strength of crossflow, outfall length and spacing of jets are also found to significantly affect dilution. / A numerical model, capable of modeling the discharge of multiple jets in a crossflow, is developed and shows significant improvement over existing models. / by Ishita Shrivastava. / Ph. D. / Ph.D. Massachusetts Institute of Technology, Department of Civil and Environmental Engineering