Thesis (S.M. in Engineering and Management)--Massachusetts Institute of Technology, Engineering Systems Division, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references. / This thesis analyzes the potential for existing natural gas combined cycle (NGCC) power generation to displace coal generation thereby reducing emissions of CO₂ and criteria pollutants regulated under the Clean Air Act. It also examines the potential for unused NGCC capacity to eliminate transmission congestion while simultaneously reducing CO₂ and other criteria pollutant emissions. The average capacity factor of the entire natural gas fleet in year 2008 was 26%. The average capacity factor of NGCC units, a subset of the gas fleet, is 41%. NGCC units, however, are designed to operate at capacity factors as high as 85%. The delta of these two numbers has generated significant policy interest as a means for reducing C02 emissions through some type of environmental dispatch that would favor NGCC over coal generation without the need for additional capital investment. The maximum potential of natural gas power generation to displace inefficient coal generation was determined. This upper limit can provide regulators and policy makers with guideposts for further review. Various operational constraints including transmission limitations were then modeled to determine the extent to which these constraints limit fuel switching opportunities. An analysis was conducted to estimate the effects of fuel switching on transmission congestion. The conclusion of this analysis was that generation from potentially available NGCC capacity located in regions with high load centers can help alleviate the transmission congestion problem with minimal or zero capital investment for building new generation capacity. Next, an hourly dispatch model was developed that incorporates many of the complexities of the power system. This model dispatches generation from various power plants under two scenarios: a carbon unconstrained scenario (base case); and a carbon constrained scenario. Under the carbon constrained scenario, dispatch preference is give to NGCC generation over coal generation. Two regions were modeled: the Electric Reliability Council of Texas (ERCOT), which is primarily Texas; and the Florida Reliability Coordinating Council (FRCC), which is primarily Florida. Results from the two cases indicate that, without compromising system reliability: In the ERCOT region, displacing some coal generation with existing and available NGCC generation would lower CO₂ emissions by nearly 22%, SO2 by 70% and NOx by 49%, compared to the base case. * In the FRCC region, displacing some coal generation with existing and available NGCC generation would lower CO₂ emissions by nearly 10%, 502 by 38% and NOx by 25%, compared to the base case. The model results also indicate that for both ERCOT and FRCC, these emissions savings can be achieved with a 10% increase in electricity prices. This translates into a cost of emissions reductions of $20/ton of CO₂ in ERCOT and $40/ton of CO₂ in FRCC. This compares to the cost of emissions reductions from corn ethanol, which is about $750/ton of CO₂, as reported by Congressional Budget Office'. Finally, a comparison was made between the results of the hourly dispatch model and the ReEDS model, a more complex model developed by Department of Energy's (DOE) National Renewable Energy Laboratory (NREL). / by Anil Rachakonda. / S.M.in Engineering and Management

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 69-72). / Over the last fifty years, diffusion researchers have sought to explain why the rate of adoption of an innovation varies over time. Some innovations are adopted quickly as compared to others, which take decades for adoption. However, the rate of adoption of an innovation is observed to follow the 'S-curve'. Diffusion modeling is an approach to analyse the process of diffusion of innovation. Several diffusion models have been developed to predict the penetration curves while many other models are developed to explain the complexities of the underlying diffusion process. From the commercial perspective, diffusion modeling is of interest to managers because of its ability to predict sales of a product. Moreover, managers use diffusion models to chalk out strategies for successful product management. This thesis classifies the two diffusion modeling approaches: aggregate and individual. In aggregate modeling approach, the target market is aggregated and analyzed as a whole. Models are developed to forecast sales, analyze the effects of marketing efforts, examine the effects technology interactions, and study cross country diffusion. In individual modeling approach, diffusion is investigated at the consumer-level. The Models incorporate individual preferences in adoption decisions and study various effects of social structure and communication patterns. We analyze these models and discuss its strengths and weaknesses. Beyond this, we identify some of the unconquered problems of multi-product interactions and show the importance of diffusion modeling in this new frontier. / by Naveen Chandra Ranganath. / S.M.

Thesis (Ph. D. in Applied Biosciences)--Massachusetts Institute of Technology, Biological Engineering Division, 2004. / Includes bibliographical references (leaves 119-130). / Tissue inhibitors of metalloproteinases (TIMPs) regulate tumor growth, progression and angiogenesis in a variety of experimental cancer models and in human malignancies. However, numerous studies have revealed important differences between TIMP family members in their ability to inhibit angiogenic processes in vitro and angiogenesis in vivo despite their universal ability to inhibit matrix metalloproteinase (MMP) activity. To address these differences, structure-function studies were conducted to identify and characterize the anti-angiogenic domains of TIMP-2, the endogenous MMP inhibitor that uniquely inhibits capillary endothelial cell (EC) proliferation and angiogenesis in vivo. Only the carboxy-terminal domain of TIMP-2 (T2C) and not the MMP-inhibitory N-terminal domain (T2N), inhibited capillary EC proliferation. Although both T2N and T2C inhibited embryonic angiogenesis, only T2C potently inhibited mitogen-stimulated angiogenesis. These findings demonstrate that TIMP-2 possesses two distinct types of anti-angiogenic activities which can be uncoupled from each other. The anti-proliferative activity of T2C was further mapped to the 24-amino acid peptide, Loop 6, which proved to be a potent inhibitor of both embryonic and nitogen-stimulated angiogenesis in vivo. Initial studies into the mechanism(s) by which Loop 6 inhibits angiogenesis revealed that the anti-proliferative effects of Loop 6 are due, at least in part, to the inhibition of cell cycle progression and not to the induction of apoptosis. This inhibition was associated with increased levels of cell cycle inhibitor p27. Although Loop 6 did not compete with bFGF for binding to its receptor, / (cont.) five potential cell surface complexes were observed in crosslinking studies of capillary EC treated with ¹²⁵I-labeled T2C or Loop 6. Finally, given the high degree of homology between TIMP-2 and TIMP-4, we hypothesized that TIMP-4 might share anti-proliferative and MMP inhibition- independent anti-angiogenic activities with TIMP-2. Our results demonstrate that although TIMP-4 inhibits capillary EC migration, it does not inhibit capillary EC proliferation. Furthermore, TIMP-4 did not result in significant inhibition of embryonic angiogenesis in the CAM. These results suggest that TIMP-2 is unique among TIMP family members in its ability to inhibit angiogenesis via two distinct pathways. One of these activities, housed within Loop 6, results in the potent inhibition of angiogenesis in vivo. / by Cecilia A. Fernández. / Ph.D.in Applied Biosciences

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 151-153). / The role of unmanned vehicles in military and commercial environments continues to expand, resulting in Shared Manned-Unmanned (SMU) domains. While the introduction of unmanned vehicles can have many benefits, humans operating within these environments must shift to high-level supervisory roles, which will require them to resolve system errors. Error resolution in current Human Supervisory Control (HSC) domains is performed using a checklist; the error is quickly identified, and then resolved using the steps outlined by the checklist. Background research into error resolution identified three attributes that impact the effectiveness of an error resolution checklist: domain predictability, sensor reliability, and time availability. These attributes were combined into a Checklist Attribute Model (CAM), demonstrating that HSC domains with high levels of complexity (e.g. SMU domains) are ill-suited to error resolution using traditional checklists. In particular, it was found that more support was required during such error identification, as data is uncertain and unreliable. A new error resolution checklist, termed the GUIDER (Graphical User Interface for Directed Error Recovery) Probabilistic Checklist, was developed to aid the human during the error identification process in SMU domains. Evaluation was performed through a human performance experiment requiring participants to resolve errors in a simulated SMU domain using the GUIDER Probabilistic Checklist and a traditional checklist tool. Thirty-six participants were recruited, and each was assigned to a single checklist tool condition. Participants completed three simulated error scenarios. The three scenarios had varying sensor reliability levels (low, medium, high) to gauge the impact of uncertainty on the usefulness of each checklist tool. The human performance experiment showed that the addition of error likelihood data using an intuitive visualization through the GUIDER Probabilistic Checklist improved error resolution in uncertain settings. In settings with high certainty, there was no difference found between the performances of the two checklists. While positive, further testing is required in more realistic settings to validate both the effectiveness of the GUIDER Probabilistic Checklist tool and the Checklist Attribute Model. / by Jacqueline M. Tappan. / S.M.

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 50-51). / Humanitarian logistics encapsulates all supply chain efforts in response to a disaster or emergency. Despite the increased focus on humanitarian supply chains, there is not a general method for measuring the supply chain response capacity. We propose a model for humanitarian response capacity based on the stock levels and supplier capacity of an organization. We evaluate the model using inventory stock level data from the United Nations Humanitarian Response Depots (UN HRD) and a combination of inventory stock level and supplier contracted replenishment time data from the New York City Office of Emergency Management (NYC OEM). Model results in response to four simulated disaster events graphically show the approximate number of people that can be served as well as the oscillations in capacity during the response and replenishment phases. Given the span from global (UN HRD) to municipal (NYC OEM) contexts, this response capacity model provides a framework for developing a more general index that can aid organizations in making important investment decisions in order to save lives with more efficient disaster response. / by Ariahna N. Knight / M.Eng.in Logistics

Thesis (M. Eng. in Logistics)--Massachusetts Institute of Technology, Engineering Systems Division, 2010. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 66-67). / The WFP's transport of food aid to Ethiopia's landlocked population is constrained by supply chain bottlenecks at the port, and limited availability of trucks for inland transport. How can the WFP supply chain be optimized to effectively operate within the given constraints? First, we assess Ethiopia's current food transport capacity - a critical factor for the WFP's ability to deliver humanitarian food aid. Specifically, we review the current and forecasted movement of goods, gather and analyze information on transport capacity versus demand, and address the impact of government policies and regulations on the road transport sector. As a result, our research helps the WFP in analyzing quantitative and qualitative factors used in selecting routes and mitigating port bottleneck issues. The results of our study may be used by the WFP and other humanitarian organizations which aid distressed populations. / by Christina Sujin Kim and Javed Singha. / M.Eng.in Logistics

Thesis (Ph. D.)--Massachusetts Institute of Technology, Engineering Systems Division, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references. / Despite growing energy security and environmental concerns about dependence on oil as a transportation fuel, gasoline remains the overwhelmingly dominant fuel used by the US automotive fleet. Numerous previous efforts to introduce alternative fuel vehicles (AFVs) fueled by hydrogen, biofuels and electricity have failed, and significant barriers to a rapid transition to AFVs remain. One technology that has achieved considerable success in the US is the gasoline hybrid-electric vehicle (HEV), which integrate gasoline and electric powertrain components to significantly improve the efficiency of gasoline use. Since their introduction in 1999, over 2 million HEVs have been sold in the US, with more than 30 HEV models available to consumers today. In this dissertation I explore the dynamics of adoption of HEVs, examining factors influencing consumer adoption of HEVs to date, and, looking forward, the role of HEVs in the emerging market for plug-in electric vehicles (EVs). In Essay 1, I examine the market for the iconic Toyota Prius HEV. While more than 1 million Prius vehicles have been sold in the US, this market has been characterized by long wait lists at Toyota dealerships, evidence of supply constraints influencing the diffusion process. The innovation diffusion literature says relatively little about supply constraints, representing diffusion as a fundamentally demand-side process. Here I develop a model of innovation diffusion that incorporates production capacity and dealer inventory. Inclusion of supply constraints improves the explanatory power of the model in the Prius case, and demonstrates that the failure to model supply constraints can bias diffusion model parameter estimates. Essay 2 is motivated by the observation that Prius sales are not uniform geographically. Sales of the Prius have clustered in regions such as the West Coast, around Washington DC and through New England, with many fewer sales of the Prius in the south and mid-west. I propose two alternative hypotheses to explain the emergence of these clusters: 1) contagion through consumers' social networks; and 2) market heterogeneity that influences consumers' adoption thresholds. I develop a model of spatial innovation diffusion that captures spatial information generation between regions and consumer discrete choice between technologies. I find that in the Prius case, adoption clustering is explained by social contagion at the local level, which amplifies heterogeneous adoption thresholds. In Essay 3, I explore the future role of HEVs as a transitional technology in the emerging market for plug-in EVs, which hold the potential to achieve deep cuts in oil consumption and greenhouse gas emissions. The technology strategy literature suggests that hybrids technologies help the transition to radical technologies, accumulating producer learning, consumer familiarity and complementary assets that spillover to the radical technology. However, EVs remain expensive, have a limited electric range and lack a ubiquitous recharging infrastructure, while HEVs are relatively cheaper and refuel from the existing gasoline refueling infrastructure. I develop a model of hybrid and electric vehicle diffusion with multiple competing entrants, finding that the smooth transition from HEVs to EVs is possible but not assured, identifying public policy and firm strategy decisions that have the potential to accelerate this transition. / by David Ross Keith. / Ph.D.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, February 2008. / Vita. / Includes bibliographical references. / Oxidatively damaged DNA has been strongly associated with cancer, chronic degenerative diseases and aging. Guanine is the most frequently oxidized base in the DNA, and generation of a guanine radical cation (G'") as an intermediate in the oxidation reaction leads to migration of a resulting cationic hole through the DNA n-stack until it is trapped at the lowest-energy sites. These sites reside at runs of guanines, such as 5'-GG-3' sequences, and are characterized by the lowest sequence-specific ionization potentials (IPs). The charge transfer mechanism suggests that hotspots of oxidative DNA damage induced by electron transfer reagents can be predicted based on the primary DNA sequence. However, preliminary data indicated that nitrosoperoxycarbonate (ONOOCO2"), a mediator of chronic inflammation and a one-electron oxidant, displayed unusual guanine oxidation properties that were the focus of present work. As a first step in our study, we determined relative levels of guanine oxidation, induced by ONOOCO2 in all possible three-base sequence contexts (XGY) within double-stranded oligonucleotides. These levels were compared to the relative oxidation induced within the same guanines by photoactivated riboflavin, a one-electron reagent. We found that, in agreement with previous studies, photoactivated riboflavin was selective for guanines of lowest IPs located within 5'-GG-3' sequences. In contrast, ONOOCO2" preferentially reacted with guanines located within 5'-GC-3' sequences characterized by the highest IPs. This demonstrated that that sequence-specific IP was not a determinant of guanine reactivity with ONOOCO2". Sequence selectivities for both reagents were double-strand specific. Selectivity of ONOOCO2 for 5'-GC-3' sites was also observed in human genomic DNA after ligation-mediated PCR analysis. / (cont.) Relative yields of different guanine lesions produced by both ONOOCO2" and riboflavin varied 4- to 5-fold across all sequence contexts. To assess the role of solvent exposure in mediating guanine oxidation by ONOOCO2", relative reactivities of mismatched guanines with ONOOCO2" were measured. The majority of the mismatches displayed an increased reactivity with ONOOCO2 as compared to the fully matched G-C base-pairs. The extent of reactivity enhancement was sequence context-dependent, and the greatest levels of enhancement were observed for the conformationally flexible guanine- guanine (G-G) mismatches and for guanines located across from a synthetic abasic site. To test the hypothesis that the negative charge of an oxidant influences its reactivity with guanines in DNA, sequence-selective guanine oxidation by a negatively charged reagent, Fe+2-EDTA, was assessed and compared to guanine oxidation produced by a neutral oxidant, y-radiation. Because both of these agents cause high levels of deoxyribose oxidation, a general method to quantify sequence-specific nucleobase oxidation in the presence of direct strand breaks was developed. This method exploited activity of exonuclease III (Exo III), a 3' to 5' exonuclease, and utilized phosphorothioate-modified synthetic oligonucleotides that were resistant to Exo III activity. This method was employed to determine sequence-selective guanine oxidation by Fe+2-EDTA complex and y-radiation and to show that both agents produced identical guanine oxidation pattems and were equally reactive with all guanines, irrespective of their sequence-specific IPs or sequence context. / (cont.) This showed that negative charge was not a determinant of Fe+2-EDTA-mediated guanine oxidation. Finally, the role of oxidant binding on nucleobase damage was assessed by studying sequence-selective oxidation produced by DNA-bound Fe+2 ions in the presence of H202. We found that the major oxidation targets were thymines located within 5'-TGG-3' motifs, demonstrating that while guanines were a required element for coordination of Fe+2 to DNA, they were not oxidized. Our results suggest that factors other than sequence-specific IPs can act as major determinants of sequence-selective guanine oxidation, and that current models of guanine oxidation and charge transfer in DNA cannot be used to adequately predict the location and identity of mutagenic lesions in the genome. / by Yelena Margolin. / Ph.D.

Thesis (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, 2012. / Cataloged from PDF version of thesis. / Includes bibliographical references (p. 104-107). / A large percentage of companies implementing ERP experience schedule and budget overruns. In the two Air Force ERP projects studied in this thesis, DoD has experienced a schedule slippage of 3-4 years and life-cycle cost estimates almost doubled in each of these projects. Given the scale and complexity of these projects, and the number of different stakeholders involved, evaluation of the delay by checking off the high-level critical success factors as per literature does no good. Misaligned incentives between stakeholders especially sponsor organization and system integrator, failure to accommodate rework in the master project plan, choosing the right contract terms, lack of in-house technical expertise, control of sponsor over project execution were some of the aspects which emerged to be important during the case study analysis; and were re-validated using the system dynamics model. The impact of the different contract models on the Critical Success Factors, depending on the level of knowledge on legacy and the completeness of requirements, has also been examined. A System Dynamics model is developed to help in evaluating Lead System Integrator v/s Project management in-house governance models. We consider factors such as the sponsor's ability to adjust the RICE component estimations and the credibility of the contractor-staff working on the project. This thesis sets an outline for importance of governance models and delving deeper onto the process of selecting a contractor and setting incentives which help align the goals of the contractor to those of the sponsor organization. / by Farrah Tazyeen. / S.M.

Thesis: M. Eng. in Logistics, Massachusetts Institute of Technology, Engineering Systems Division, 2015. / Cataloged from PDF version of thesis. / Includes bibliographical references (pages 68-69). / This thesis focuses on a medical device manufacturer, DeCo, which offers surgical instruments to customers at no cost in order to facilitate the sale of implantable products that require the use of such instruments. DeCo is facing challenges in managing the supply chain for these outsourced instruments, such as long lead times, inaccurate forecasting, and excess inventory. Deco is interested in building a more responsive supply chain. To this end, our thesis investigated strategies to increase the supply chain agility by realizing opportunities in information flows, material movement, and channel alignment to achieve shorter lead time, lower inventory levels, and higher levels of service. We conducted interviews and analyzed forecast, inventory, and lead time data files to evaluate the company's supply chain agility in terms of key attributes such as: Inventory management, supply chain visibility, forecast, distribution channel management, supplier manufacturing flexibility, forecast, level of service, lead-time, and product lifecycle. Gaps between the current state and an agile supply chain were identified, and recommendations were made based on these weaknesses. Gaps in the supply chain were divided into three categories: information barriers, operational inflexibilities, and supply chain misalignments. Similarly, our recommendations were broken up into three main groups: Distributor strategies, supplier strategies, and DeCo's practices. By improving supply chain visibility, Deco can cut lead time to customers and significantly lower inventory. By gaining operational flexibility, DeCo can cut lead time from suppliers by 50%, avoid excess ordering due to minimum order quantity, and cut cost per unit. Key recommendations to achieve agility were to build a database of inventory at distributors' warehouses and implement a process to ship instruments between these warehouses; and to work with suppliers to build dedicated capacity on the production floor. / by Xinye Bai and Yaniv Rosenberg. / M. Eng. in Logistics