Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, Technology and Policy Program, 2005. / Includes bibliographical references (p. 213-217). / Satellite communication systems remain one of the most under utilized development mediums in less industrialized countries. This research proposes to establish a low cost satellite communications system tailored specifically for the developing world (+/- 30⁰ latitude). The technical, economic and policy related frontiers of the problem are integrated within a MATLAB based satellite communication constellation simulation which is used to assess the feasibility of the proposed satellite system. The analysis demonstrates that with technical advances that would allow higher capacity systems at lower costs and a renewed policy framework in line with the present state of the satellite system industry, it could be feasible to establish a low earth orbit satellite communications system for the developing world. The inputs to the satellite simulation are the proposed system's desired design variables and other relevant parameters. The outputs are system performance, capacity and cost. The Pareto optimal solution trade space is generated by the simulation model using a full-factorial run that probes the entire design space. The application of choice is short messaging services (SMS), chosen for its ability to provide proven connectivity at moderate costs. The capacity and cost of the most ideal Pareto architecture is contrasted against demand in the defined developing world region. The simulation also accounts for the necessary policy considerations and assesses the feasibility of the proposed system amidst the existing industry policy and regulatory framework. Additionally, data regarding the current economic standing of the region and how this forms an underlying basis for the digital divide is presented and assessed. / (cont.) The policy and regulatory constraints on the acceleration of telecommunications development throughout the developing world are discussed. This thesis elaborates upon the need for a focus on design for affordability if satellite communication systems are to realize their immense potential for the delivery of needed social services to the world's marginalized. / by Ayanna Terehas Samuels. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2005. / Includes bibliographical references (leaf 65). / This thesis documents the testing of a prototype of a smartphone to be used by roadway workers and dispatchers that was based in a wireless data link service. The main purpose of using a smartphone in railroad communications is to eliminate errors due to radio and pronunciation deficiencies. Previous studies analyzed the communication environment of the dispatcher in order to address questions based upon data link becoming a means for sending and receiving information in railroad operations. These studies have examined what kind of information is appropriate for each medium (voice and visual), and by what criteria a dispatcher will select which communication medium. Building on these studies, this work presents a comparison between a radio and data link mediums for a long communication of a characteristic type: assignment of a form D. This thesis reports on the on site testing of the data link system which proved to be useful and efficient in certain aspects of railroad applications. The new system was faster and more effective than the radio communication when used to convey long messages such as filling out Form Ds. The radio communication was faster than the datalink for confirmation communications that only require yes/no answers. One reason for this difference appears to be the users' unfamiliarity with the device. The time to convey short messages could also be reduced after the users become more proficient with the new system. The document also includes an analysis of the regulatory challenges that the new system would bring. A list or recommendations for the new regulations are presented at the end of the report. / by Neslihan Iclal Doran. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2003. / Includes bibliographical references (leaves 74-75). / Product development and innovation involve uncertainty, which inevitably incurs risk. Especially, as product development cycles shorten and resources condense, and as the products themselves grow more complex, managing risk in product developments is increasingly important. In the product development process, product verification plays an important role in risk management by verifying the performance of products under development and evaluating product-development risk. This thesis addresses the problem of risk management in automobile product verification. It looks at the product development and verification processes as an exercise in risk reduction. Risk in product verification is defined as the probability that performance estimates resulting from CAE simulations or physical tests will not satisfy requirement targets. Based on probabilistic methods and estimation theory, the thesis applies a mathematical model to assess the risk involved in product verification and provides a set of spreadsheet tools to emulate the evolution of performance estimates. The proposed model is employed to analyze practical cases using data from the Ford Motor Company. An optimization simulation suggests greater investment in early stages of product verification results in lower overall risk. / by Peng Zhang. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Technology and Policy Program, 2005. / Includes bibliographical references (p. 98-109). / (cont.) We describe the ethical debate and political climate that led to the decision. An examination of the publication data shows that researchers in the United States have in fact remained leaders in the field until this point, in part because U.S. federal funding has also been available to early mover international groups who appear to have abided by the restrictions. / Restoring damaged or diseased tissue in the body may involve the use of biomaterial scaffolds that provide a responsive environment for cell proliferation. Such scaffolds may be used for in situ cell regeneration, where an implanted scaffold incites cell growth in the body, as well as for growing artificial tissue in vitro by seeding cells in a scaffold that will be implanted at a later stage of development or used for physiological tissue models. The research outlined in this thesis describes two methods of characterizing the stiffness of a biomaterial scaffold. It is well known that cell growth in vitro is affected by the moduli of the surrounding scaffold. Stiffness is also cited as a major factor affecting angiogenesis, the formation of new blood vessels. We describe a new rheometric method to examine the bulk mechanical properties of a self-assembling peptide biomaterial that spontaneously forms a filament network in a physiological salt solution and supports cell attachment and differentiation. This method has two major advantages: first, it reduces the time per sample and second, it can be used to analyze materials where cross-linkers must be added and washed out. We also have also used fluorescence microscopy and wrote a program to find the persistence length of actin filaments in the eventuality that peptide filaments can be reliable isolated. This self-assembling peptide biomaterial has shown great promise as a scaffold for differentiated cells and has also been shown to support adult liver stem cells. Therefore it is likely that it can support human embryonic stem cells. The second half of this thesis describes the ramifications of the policy decision on August 9, 2001 to limit federal funding to existing cell lines. / by Gina Kim. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2005. / Includes bibliographical references (p. 147-150). / Long term human space exploration depends on the development of a sustainable heavy lift launch vehicle (HLLV). But what exactly is sustainability in the context of launch systems and how can it addressed in the design process? A HLLV must balance myriad technical and programmatic factors such as performance, reliability, cost, geographical configuration, logistics and assembly, as well as in-space issues such as mass and manifesting requirements for Lunar and Mars missions, and rendezvous and docking capability. The problem is further complicated by uncertainties in demand and differing stakeholder incentives. The military significance of space launch creates security externalities that often constrain design; "standing armies" of technicians and operators throughout the country affect industry and political interests; and scientific goals are often at odds with all three. The multi-dimensional nature of the design problem suggests that sustainability is best addressed at the system architecture level, where direct links can be made between technical and non-technical aspects of system operation. This thesis examines the problem of designing sustainable heavy lift architectures in three ways: First, recent advances in systems architecture are synthesized as they apply to heavy lift launch. / (cont.) Sustainability is defined more precisely, as are the counterbalancing dynamics of adaptability and architectural lock-in. Second, cases are studied to understand how the previously defined concepts have played out in practice. The evolution of system architectures leading to the development of the last heavy lift vehicle, Saturn V, is analyzed; and the problem of reducing cost in the modern launch industry is examined from a political-economic perspective. Finally, insights from these studies together with recent advances in engineering economy are used to develop quantitative models to compare architectures. An analytic model is created to evaluate mission cost and risk as a function of vehicle capacity and in-space requirements. A discrete model based on real-options thinking is developed to compare Space Shuttle-derived and Evolved Expendable Launch Vehicle (EELV) derived architectures. / by Matthew Robin Silver. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2008. / Includes bibliographical references (p. 121-129). / An exploration of the health implications of aviation emissions regulations is made by assessing the results of a study of aviation's effects on United States air quality mandated by the Energy Policy Act of 2005. The Energy Policy Act study results estimated that aviation is responsible for 160 yearly incidences (with a 90% confidence interval of 64 to 270 incidences) of premature mortality of adults age 30 and over ($882 million in year 2001 dollars, with a 91% CI of $196 to $1830 million) due to exposure to particulate matter below 2.5 /im in size (PM2.5) in the continental U.S. as reported by the Environmental Benefits Mapping and Analysis Program (BenMAP). Strong regional differences were noted; for instance, 18% of the total health incidences and costs occurred in Los Angeles County. Aviation was estimated to decrease ozone concentrations, causing small premature mortality disbenefits (health effects avoided due to the presence of aviation) of approximately 2 yearly premature mortality incidences ($9 million). Primary particulate matter values in the Energy Policy Act study's emissions inventory had been generated using a conservatively biased version of the First Order Approximation method version 3.0 (FOA3), known as FOA3a, and the emissions of sulfur oxides (SOx) had been incorrectly computed (underestimated by approximately 15%). To quantify the effects of these differences on health impacts, a comparison was made with a second inventory generated by CSSI, Inc. using FOA3. Based on the comparison, it is estimated that aviation was responsible for 140 to 160 yearly incidences of premature mortality from exposure to PM. 46% to 69% of the incidences were estimated to be due to changes in concentrations of ammonium sulfate secondary PM from SOx, while ammonium nitrate secondary PM was estimated to be responsible for 18% to 20%. / (cont.) Concentrations of volatile primary PM from organic compounds and nonvolatile primary PM were responsible for 6% - 18% and 5% - 14% of the impact, respectively, while volatile primary PM from sulfates was responsible for 0% to 4%. Confidence intervals were not computed, and only the effects of changes in PM concentrations were assessed. Based on the results, it is determined that changing regulations governing nitrogen oxide (NOx) emissions and fuel sulfur content may be effective strategies to mitigate incidences of premature mortality due to aviation. An assessment was made of the effects of changing fuel sulfur concentration from 600 parts per million (ppm), as is typical of current jet fuel, to 15 ppm across the continental U.S. It is estimated that this change would reduce yearly premature mortality incidences due to aviation-related ambient PM exposure by 38%. Confidence intervals were not computed. The cumulative additional costs to refineries to produce 15-ppm fuel could be approximately $260 million, suggesting that the benefits may be comparable to the costs. However, such a strategy could have climate warming impacts since aviation sulfur emissions have a cooling influence on climate. It is also estimated that an immediate deployment of ultra-low sulfur fuel only for takeoffs from Los Angeles County could reduce aviation-related nationwide yearly incidences of mortality by 10%, with Los Angeles County health impacts bring reduced by a factor of 2. The additional costs to refineries may be approximately $12 million, suggesting that such a policy may be cost-beneficial. Finally, a brief exploration is done of a NOx stringency assessment by the International Civil Aviation Organization's Forecasting and Economic Analysis Support Group (FESG), which predicted that an industry-wide investment of $30,000 - $40,000 would be required for every tonne of NOx eliminated if the ICAO NOx standard were to be increased by 10% in the year 2008. / (cont.) FESG found this to be the most cost-effective NO, reduction strategy. A direct comparison with the Energy Policy Act and RSM results is difficult, yet an assessment finds that NO, has health costs of only $2,000 per tonne in both sets of results. / by Christopher J. Sequeira. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M. in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 121-128). / Even with advances in vehicle technology, both conservation and methods for reducing the fuel consumption of existing vehicles are needed to decrease the petroleum consumption and greenhouse gas emissions of the U.S. light-duty vehicle fleet. One way to do this is through changes in driving style, specifically through reductions in driving aggressiveness. The role of vehicle performance is particularly interesting because of the recognized tradeoff between vehicle performance and certified fuel consumption and because more powerful vehicles are capable of more aggressive driving. This thesis analyzes the effects of driving style and vehicle performance on the real-world fuel consumption of conventional vehicles though two parts. First, vehicle simulations assess the sensitivity of fuel consumption to a wide range of driving patterns. From these results, three aggressiveness factors were developed for quantifying driving aggressiveness. Each aggressiveness factor, although based only on the speed trace and vehicle characteristics, is proportional to fuel consumption in one of three specific speed ranges: neighborhood, city, or highway speeds. These aggressiveness factors provide a tool for comparing drive cycles and evaluating the real-world driving patterns. Second, driving data from two U.S. sources was used to 1) provide illustrative examples of real world driving and 2) assess the relationship between driving aggressiveness and vehicle performance. The distribution of aggressiveness among the driving data follows a lognormal shape. The average aggressiveness is either below or near the aggressiveness of the U.S. drive cycles developed in the 1990s. Moderate performance vehicles, the most common type of vehicle, are driven most aggressively. Low performance vehicles are driven least aggressively. The results suggest that, for the illustrative data analyzed in this work, reducing velocities during highway driving would save roughly the same amount of fuel as reducing accelerations during all driving. However, on an individual basis, the fuel savings achieved from these behaviors would vary significantly. Aggressive drivers should focus on reducing accelerations, while less aggressive drivers should focus on driving at lower speeds on the highway. And the greatest fuel savings can be attained if the most aggressive drivers, those who drive moderate performance vehicles, drove with lower accelerations. / by Irene Michelle Berry. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2002. / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / "June 2002." Page 187 blank. / Includes bibliographical references (p. 180-184). / by Aaron L. Kirtley. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2003. / Includes bibliographical references (p. 149-152). / Sustainable success in product design and development relies not only on technical expertise and creativity within the company but as crucially, if not more, on an intelligent design of the development process, an appropriate and dynamic management of organizations, a realistic and disciplined project management, and on efficient knowledge generation, conservation and distribution techniques. These non-engineering skills pose serious challenges to companies designing complex systems like airplanes or automobiles. As these systems have gotten tremendously more complex, their design has kept involving more people, from different working cultures inside and outside the company, all within tighter time constraints. Adaptation to this new context of product development has nevertheless often been very slow because of persistent corporate traditions inherited from the past. The purpose of this thesis is to demonstrate that Process Mapping and Improvement, Organizations Management, Project Management and Knowledge Management can be reconciled and performed all at once using the Design Structure Matrix (DSM) Method, enabling large and relatively easy improvements of the design activity's efficiency. The state-of-the-art in each of the four mentioned fields is first reviewed. The methodology used throughout this thesis, the Design Structure Matrix (DSM) is then presented. The DSM method and some issues of knowledge management are illustrated in a short case study conducted in January 2002 at PSA Peugeot-Citroen in Paris, France. The promising unifying benefits of the DSM method are then thoroughly described through a large project that took place in Summer 2002 at Ford Motor Company in Dearborn, Michigan. It exhibits how DSMs can provide permanent system-level knowledge, guide the design practitioner through a complex process that would hardly be understood otherwise, enable a dynamic management of organizations and open opportunities for process improvement and redesign. The lessons learned finally lead to recommendations on the practice of the DSM method as well as product development in general. / by Antoine D. Guivarch. / S.M.

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2004. / Includes bibliographical references (p. 31-32). / Requirements management is an extremely critical and challenging part of the software development process. Correctly capturing these requirements is necessary for the user to be satisfied with the final product. Many instances of inadequate requirements management result in subsequent problems with the final product and have organizational sources. The goal of this research is to better understand the organizational processes and problems associated with software requirements management within NASA's human-rated space programs through interviews with experienced professionals within this organization. Some of the major themes that resulted from the expert interviews include: * Software engineering practices, such as the CMM, are starting to be implemented for the larger programs at NASA, however these practices have not been equally pervasive in all parts of the organization. * The main reason for lack of requirements management at NASA is not enough time or people available for the activity. * The reason that was most cited for requirements management tools not being used effectively is that these tools are too manpower intensive for NASA's current organizational situation, and require documentation that is not available. * To achieve improvements in requirements management NASA should hire more people with computer science backgrounds who also have an understanding of aerospace systems. * The lack of complete documentation on NASA projects, means that complete system testing cannot happen. * Requirements creep can happen at NASA because higher level customers do not always have a complete technical understanding of a subsystem or component that is / (cont.) being developed, and the designers may interpret or change a requirement without consulting the customer. * NASA often deals with managing relationships between different subcontractors who have responsibility for different parts of the software lifecycle, and each subcontractor has its' own interests and stake in the final outcome of the system. It is important that NASA adequately manages the requirements between these parties to ensure that the customer's system requirements do not become distorted by the political interests of the subcontractors. Finally some recommendations for further research in this area are made. Thesis Supervisor: Charles P. Coleman / by Laurie L. Rodriguez. / S.M.