1. The 2017 eastern Bering Sea continental shelf and northern Bering Sea bottom trawl surveys : results for commercial crab species [2018] Online
- Book
- 1 online resource (viii, 233 pages) : color illustrations, maps (some color).
- Collection
- Government Information United States Federal Collection
"The eastern Bering Sea bottom trawl survey has been conducted annually since 1975 by the Resource Assessment and Conservation Engineering Division of the Alaska Fisheries Science Center, National Marine Fisheries Service. The purpose of this survey is to collect data on the distribution and abundance of crab, groundfish, and other benthic resources in the eastern Bering Sea. These data are used to estimate population abundances for the management of commercially important species in the region. This document includes the time series of results from 1975 to the present. In 2017, 395 total stations (375 standard stations and 20 resampled stations in Bristol Bay) were sampled on the eastern Bering Sea shelf from 4 June to 15 August. In early June, colder bottom temperatures extended into Bristol Bay creating the need to resample 20 stations due to delaying effects of cold water temperature on red king crab reproductive cycle. There was an overall decrease in biomass and abundance in male red king and blue king crab and female red king crab. There was an overall increase in immature female blue king crab and a decrease in mature female biomass and abundance, with no mature female blue king crab being caught in the St. Matthew Island Section. There were overall increases in immature and legal male and immature and mature female biomass and abundance in Chionoecetes bairdi and C. opilio crab, and a decrease in mature male biomass and abundance in Chionoecetes bairdi and C. opilio crab. In addition to the standard eastern Bering Sea survey, in 2017, following the conclusion of the standard survey, 145 stations were sampled in the northern Bering Sea region, encompassing the region south of Bering Strait and including Norton Sound. These stations were sampled between 1 August and 2 September. We report the results of this survey separately from the eastern Bering Sea survey, within the northern Bering Sea section of this report. Blue king crabs occurred largely in the region north of St. Lawrence Isand, in greater densities than were observed for the St. Matthew and Pribilof stocks. Red king crab occurred primarily in Norton Sound, at densities roughly intermediate between those generally observed in the Bristol Bay and Pribilof Districts. Chionoecetes opilio dominated the catch, with the highest densities observed during the 2017 Bering Sea survey occurring to the south of St. Lawrence. Immature male and female opilio were predominate, although mature females were observed, primarily along the western edge of the survey grid, and in the north, near Bering Strait. Morphometrically mature (“large-clawed”) male C. opilio were scattered throughout the survey region, but most prevalent within catch near Bering Strait."--Publisher's website.
"The eastern Bering Sea bottom trawl survey has been conducted annually since 1975 by the Resource Assessment and Conservation Engineering Division of the Alaska Fisheries Science Center, National Marine Fisheries Service. The purpose of this survey is to collect data on the distribution and abundance of crab, groundfish, and other benthic resources in the eastern Bering Sea. These data are used to estimate population abundances for the management of commercially important species in the region. This document includes the time series of results from 1975 to the present. In 2017, 395 total stations (375 standard stations and 20 resampled stations in Bristol Bay) were sampled on the eastern Bering Sea shelf from 4 June to 15 August. In early June, colder bottom temperatures extended into Bristol Bay creating the need to resample 20 stations due to delaying effects of cold water temperature on red king crab reproductive cycle. There was an overall decrease in biomass and abundance in male red king and blue king crab and female red king crab. There was an overall increase in immature female blue king crab and a decrease in mature female biomass and abundance, with no mature female blue king crab being caught in the St. Matthew Island Section. There were overall increases in immature and legal male and immature and mature female biomass and abundance in Chionoecetes bairdi and C. opilio crab, and a decrease in mature male biomass and abundance in Chionoecetes bairdi and C. opilio crab. In addition to the standard eastern Bering Sea survey, in 2017, following the conclusion of the standard survey, 145 stations were sampled in the northern Bering Sea region, encompassing the region south of Bering Strait and including Norton Sound. These stations were sampled between 1 August and 2 September. We report the results of this survey separately from the eastern Bering Sea survey, within the northern Bering Sea section of this report. Blue king crabs occurred largely in the region north of St. Lawrence Isand, in greater densities than were observed for the St. Matthew and Pribilof stocks. Red king crab occurred primarily in Norton Sound, at densities roughly intermediate between those generally observed in the Bristol Bay and Pribilof Districts. Chionoecetes opilio dominated the catch, with the highest densities observed during the 2017 Bering Sea survey occurring to the south of St. Lawrence. Immature male and female opilio were predominate, although mature females were observed, primarily along the western edge of the survey grid, and in the north, near Bering Strait. Morphometrically mature (“large-clawed”) male C. opilio were scattered throughout the survey region, but most prevalent within catch near Bering Strait."--Publisher's website.
2. 2FLOWS: A Smart Dual-Flow Sink [2018] Online
- Collection
- ME310 Project Based Engineering Design
As the water infrastructure in the US is aging, with many water distribution pipes installed 50 or more years ago, the process of replacing such infrastructure is projected to cost about $1 trillion. Our project sponsor Xylem asked us to design a solution around such a wicked problem. The ME310 Xylem team conducted user needfinding, defined the problem, pivoted towards darkhorse prototypes, created funktional and functional prototypes, and finally developed the solution called 2FLOWS. 2FLOWS is a smart dual-flow sink that automatically detects and diverts greywater from blackwater, giving greywater a second life for purposes such as irrigation and other non-potable uses within the building (e.g., toilet flushing). As much of the water from commercial buildings are in fact reusable, the diversion and reuse of greywater effectively reduces the load on pipes to water treatment and also prevents unnecessary full treatment of the water. Through needfinding we found that there is a huge mismatch between water-saving intentions and actions, but our instances of user testing have shown that 2FLOWS brings about a unique user experience that allows already water-conscious citizens to bridge this intention-to-action gap. We also found that 2FLOWS brings the conversation and awareness of water-consciousness, which is the first step towards a more sustainable infrastructure. We envision 2FLOWS to be advantageous and vital to the decentralized paradigm that we introduce as the solution to the issue of aging water infrastructure.
As the water infrastructure in the US is aging, with many water distribution pipes installed 50 or more years ago, the process of replacing such infrastructure is projected to cost about $1 trillion. Our project sponsor Xylem asked us to design a solution around such a wicked problem. The ME310 Xylem team conducted user needfinding, defined the problem, pivoted towards darkhorse prototypes, created funktional and functional prototypes, and finally developed the solution called 2FLOWS. 2FLOWS is a smart dual-flow sink that automatically detects and diverts greywater from blackwater, giving greywater a second life for purposes such as irrigation and other non-potable uses within the building (e.g., toilet flushing). As much of the water from commercial buildings are in fact reusable, the diversion and reuse of greywater effectively reduces the load on pipes to water treatment and also prevents unnecessary full treatment of the water. Through needfinding we found that there is a huge mismatch between water-saving intentions and actions, but our instances of user testing have shown that 2FLOWS brings about a unique user experience that allows already water-conscious citizens to bridge this intention-to-action gap. We also found that 2FLOWS brings the conversation and awareness of water-consciousness, which is the first step towards a more sustainable infrastructure. We envision 2FLOWS to be advantageous and vital to the decentralized paradigm that we introduce as the solution to the issue of aging water infrastructure.
3. 3D particle concentration measurement in turbulent flows using magnetic resonance imaging [2018] Online
- Book
- 1 online resource.
Turbulent, dispersed multiphase flows are of critical importance in a wide range of application areas. Experimental investigations are indispensable in the study of such flows, as experiments can provide reliable domain-specific knowledge and/or validation for computational fluid dynamics (CFD) tools. However, only a limited set of experimental techniques currently are available for studying particle-laden flows: pointwise measurements provide high temporal resolution but poor spatial coverage, while laser-based techniques can allow for 2D or 3D measurements, but only in geometrically simple flows. Magnetic Resonance Imaging (MRI) is a powerful tool that can provide fully quantitative, 3D experimental data without the need for optical access. Currently, MRI can provide the time-averaged, 3-component velocity and/or scalar concentration fields in turbulent single-phase flows of arbitrary geometric complexity. In recent years MRI has been applied to the study of single-phase flows across a broad range of problems from the engineering, environmental, and medical arenas. MRI data sets are particularly well suited for validating CFD simulations of complex 3D flows because comprehensive data coverage can be obtained in a relatively short time. The present work describes development, validation, and application of a new diagnostic, wherein MRI is used to obtain the 3D mean volume fraction field for solid microparticles dispersed in a turbulent water flow. The new method is referred to as Magnetic Resonance Particle concentration, or MRP. This technique was designed to maintain the same advantages of existing MRI-based techniques: quantitative data can be obtained in 3D for fully turbulent flow in arbitrarily complex geometries. MRP is based on a linear relationship between the MRI signal decay rate and particle volume fraction (Yablonskiy and Haacke, 1994). The MRP method and underlying physics were validated through several studies, increasing in complexity from a single particle suspended in a gel to a fully turbulent channel flow seeded uniformly with particles. The channel flow case showed that the signal decay rate varied linearly with particle volume fraction, and that the measured proportionality constant was within 5% of the value predicted by the theory of Yablonskiy and Haacke (1994). This good agreement was observed for two fully turbulent Reynolds numbers, 6300 and 12,200, and over most of the measurement domain. However, the measured proportionality constant was lower than expected in the the furthest upstream portion of the channel; several potential reasons for this discrepancy were identified, but none could be proven conclusively at this stage. Following the validation experiments, MRP was applied to three application cases drawn from real-world flows of interest. First, the dispersion of two particle streaks in a model human nasal passage was studied. The results showed that almost all particles reaching the upper portions of the nasal passage (e.g., the olfactory region) entered the nose near the nostril tip, even at high breathing rates where the flow was not laminar. The second case involved MRP concentration measurements for a particle streak in a generic gas turbine blade internal cooling passage. Results in this case provided evidence that small dust-like particles ingested into a cooling passage may behave inertially in the presence of fine flow features, such as the recirculation regions behind ribbed flow turbulators. In the final case, the performance of a particle separator device proposed by Musgrove et al. (2009) was quantified using both MRP and a sample-based analysis performed outside the MRI environment. The two techniques were in agreement regarding the poor overall effectiveness of the separator, and the 3D MRP data were used to examine the particle transport physics and suggest potential design improvements. Taken together, results from the three test cases showed that MRP can provide quantitative, 3D particle concentration data in application-relevant flows, leading to unique insights that would not be possible with existing measurement techniques.
Turbulent, dispersed multiphase flows are of critical importance in a wide range of application areas. Experimental investigations are indispensable in the study of such flows, as experiments can provide reliable domain-specific knowledge and/or validation for computational fluid dynamics (CFD) tools. However, only a limited set of experimental techniques currently are available for studying particle-laden flows: pointwise measurements provide high temporal resolution but poor spatial coverage, while laser-based techniques can allow for 2D or 3D measurements, but only in geometrically simple flows. Magnetic Resonance Imaging (MRI) is a powerful tool that can provide fully quantitative, 3D experimental data without the need for optical access. Currently, MRI can provide the time-averaged, 3-component velocity and/or scalar concentration fields in turbulent single-phase flows of arbitrary geometric complexity. In recent years MRI has been applied to the study of single-phase flows across a broad range of problems from the engineering, environmental, and medical arenas. MRI data sets are particularly well suited for validating CFD simulations of complex 3D flows because comprehensive data coverage can be obtained in a relatively short time. The present work describes development, validation, and application of a new diagnostic, wherein MRI is used to obtain the 3D mean volume fraction field for solid microparticles dispersed in a turbulent water flow. The new method is referred to as Magnetic Resonance Particle concentration, or MRP. This technique was designed to maintain the same advantages of existing MRI-based techniques: quantitative data can be obtained in 3D for fully turbulent flow in arbitrarily complex geometries. MRP is based on a linear relationship between the MRI signal decay rate and particle volume fraction (Yablonskiy and Haacke, 1994). The MRP method and underlying physics were validated through several studies, increasing in complexity from a single particle suspended in a gel to a fully turbulent channel flow seeded uniformly with particles. The channel flow case showed that the signal decay rate varied linearly with particle volume fraction, and that the measured proportionality constant was within 5% of the value predicted by the theory of Yablonskiy and Haacke (1994). This good agreement was observed for two fully turbulent Reynolds numbers, 6300 and 12,200, and over most of the measurement domain. However, the measured proportionality constant was lower than expected in the the furthest upstream portion of the channel; several potential reasons for this discrepancy were identified, but none could be proven conclusively at this stage. Following the validation experiments, MRP was applied to three application cases drawn from real-world flows of interest. First, the dispersion of two particle streaks in a model human nasal passage was studied. The results showed that almost all particles reaching the upper portions of the nasal passage (e.g., the olfactory region) entered the nose near the nostril tip, even at high breathing rates where the flow was not laminar. The second case involved MRP concentration measurements for a particle streak in a generic gas turbine blade internal cooling passage. Results in this case provided evidence that small dust-like particles ingested into a cooling passage may behave inertially in the presence of fine flow features, such as the recirculation regions behind ribbed flow turbulators. In the final case, the performance of a particle separator device proposed by Musgrove et al. (2009) was quantified using both MRP and a sample-based analysis performed outside the MRI environment. The two techniques were in agreement regarding the poor overall effectiveness of the separator, and the 3D MRP data were used to examine the particle transport physics and suggest potential design improvements. Taken together, results from the three test cases showed that MRP can provide quantitative, 3D particle concentration data in application-relevant flows, leading to unique insights that would not be possible with existing measurement techniques.
4. A Break in the Cloud: Finding the Local in the Global Internet [2018] Online
The Internet has radically changed every mode of production, distribution, and consumption in modern life, granting global access to information transcending time and space. However, the physical infrastructure that enables the Internet is often overlooked, due to the virtual and intangible nature of Internet connection. This disconnect between the digital and the physical is captured by the popular buzzword - “the cloud” - a metaphor that abstracts away the vast, energy-guzzling tracts of data server farms kept hidden in corporate secrecy. This thesis seeks to make “the cloud” visible and concrete, and in doing so, zooms in from the Internet’s “global village”1 back to the physical realities of Internet infrastructure embedded within local communities. Through an analysis and synthesis of technical papers, corporate marketing, policy reports, and maps, it situates the “global” nature of the cloud within national and local politics and communities. In addition, through a case study of Google’s first data center in The Dalles, Oregon, and its intimate relationship with a community-piloted municipal fiber network - QLife Network - this thesis brings local community needs and negotiations in conversation with the global corporate order of digital technologies. The discussion concludes with a proposed framework for a community-oriented approach to accessing the global Internet, urging for visibility through new media art and community-based Internet infrastructure investment. Recognizing the realities of local within a global Internet makes the first necessary step in bringing the cloud out of its technological black box, and in short, finding the break in the cloud.
The Internet has radically changed every mode of production, distribution, and consumption in modern life, granting global access to information transcending time and space. However, the physical infrastructure that enables the Internet is often overlooked, due to the virtual and intangible nature of Internet connection. This disconnect between the digital and the physical is captured by the popular buzzword - “the cloud” - a metaphor that abstracts away the vast, energy-guzzling tracts of data server farms kept hidden in corporate secrecy. This thesis seeks to make “the cloud” visible and concrete, and in doing so, zooms in from the Internet’s “global village”1 back to the physical realities of Internet infrastructure embedded within local communities. Through an analysis and synthesis of technical papers, corporate marketing, policy reports, and maps, it situates the “global” nature of the cloud within national and local politics and communities. In addition, through a case study of Google’s first data center in The Dalles, Oregon, and its intimate relationship with a community-piloted municipal fiber network - QLife Network - this thesis brings local community needs and negotiations in conversation with the global corporate order of digital technologies. The discussion concludes with a proposed framework for a community-oriented approach to accessing the global Internet, urging for visibility through new media art and community-based Internet infrastructure investment. Recognizing the realities of local within a global Internet makes the first necessary step in bringing the cloud out of its technological black box, and in short, finding the break in the cloud.
The mosquito Aedes albopictus, originating from southeast Asia, has expanded throughout the world during the 20th century, adapting to a variety of different regions and habitats and spreading diseases such as dengue, chikungunya, and Zika. Within these invasive populations little is known about the genetic diversity and population structure, particularly in Central America. Previous studies on the diversity of Ae. albopictus have been performed in countries such as the United States and Malaysia; however, few studies have examined population structure, genetic diversity, and phylogenetic relationship of Ae. albopictus populations in Central America, where dengue and other viruses are actively spreading. Understanding these important genetic markers and relationships will guide future research to allow for more direct targeting of vector control efforts. Ae. albopictus were captured using five different trapping methods in locations covering a wide range of land uses and temperatures across southern Costa Rica. We assessed population genetic structure by sequencing the mitochondrial Cytochrome C Oxidase 1 (CO1) gene. A phylogenetic tree constructed from our Costa Rican sequences and other world population sequences revealed a slight clustering of the Costa Rican population with populations from temperate regions. Examination of our sequences also revealed little population structuring, which indicates that the geographically separated populations are still intermixing despite the barriers that exist. Understanding the genetics of the Ae. albopictus within Costa Rica will be fundamental to future research to determine how the species will respond to the anthropogenic changes in temperature and land use in southern in Costa Rica. This in turn could aid in proactive mosquito control and public health management to reduce the incidence of the mosquito-borne viral infections.
The mosquito Aedes albopictus, originating from southeast Asia, has expanded throughout the world during the 20th century, adapting to a variety of different regions and habitats and spreading diseases such as dengue, chikungunya, and Zika. Within these invasive populations little is known about the genetic diversity and population structure, particularly in Central America. Previous studies on the diversity of Ae. albopictus have been performed in countries such as the United States and Malaysia; however, few studies have examined population structure, genetic diversity, and phylogenetic relationship of Ae. albopictus populations in Central America, where dengue and other viruses are actively spreading. Understanding these important genetic markers and relationships will guide future research to allow for more direct targeting of vector control efforts. Ae. albopictus were captured using five different trapping methods in locations covering a wide range of land uses and temperatures across southern Costa Rica. We assessed population genetic structure by sequencing the mitochondrial Cytochrome C Oxidase 1 (CO1) gene. A phylogenetic tree constructed from our Costa Rican sequences and other world population sequences revealed a slight clustering of the Costa Rican population with populations from temperate regions. Examination of our sequences also revealed little population structuring, which indicates that the geographically separated populations are still intermixing despite the barriers that exist. Understanding the genetics of the Ae. albopictus within Costa Rica will be fundamental to future research to determine how the species will respond to the anthropogenic changes in temperature and land use in southern in Costa Rica. This in turn could aid in proactive mosquito control and public health management to reduce the incidence of the mosquito-borne viral infections.
6. A forward genetic screen identifies new host factors influencing bacteriophage lambda's lysis-lysogeny decision [2018] Online
- Collection
- Undergraduate Theses, School of Engineering
In order to survive, organisms must integrate internal and external signals via complex signaling pathways to intelligently navigate their environment. Bacteriophage lambda has long been a classic model for understanding such pathways, and how they allow cells to effect changes in physiology in order to adapt to varying circumstances. When infecting its host Escherichia coli, phage lambda may either make more viruses (lysis), or integrate itself into the host genome (lysogeny). To better understand the extent to which host physiology influences the lysis-lysogeny decision, I performed a forward genetic screen to identify genes whose deletions bias the infected cell towards lysis or lysogeny. This screen revealed numerous host-encoded genes linked to the lysis-lysogeny decision, including transcription factors and genes in metabolic pathways. These results demonstrate previously unknown links between host physiology and viral decision-making, shedding new light on this classic model system.
In order to survive, organisms must integrate internal and external signals via complex signaling pathways to intelligently navigate their environment. Bacteriophage lambda has long been a classic model for understanding such pathways, and how they allow cells to effect changes in physiology in order to adapt to varying circumstances. When infecting its host Escherichia coli, phage lambda may either make more viruses (lysis), or integrate itself into the host genome (lysogeny). To better understand the extent to which host physiology influences the lysis-lysogeny decision, I performed a forward genetic screen to identify genes whose deletions bias the infected cell towards lysis or lysogeny. This screen revealed numerous host-encoded genes linked to the lysis-lysogeny decision, including transcription factors and genes in metabolic pathways. These results demonstrate previously unknown links between host physiology and viral decision-making, shedding new light on this classic model system.
7. A Juxtaposition of Stakeholder Perceptions of Prevalent Issues in Higher Education Law and Policy [2018] Online
- Collection
- Stanford Research Data
Universities embrace a plethora of stakeholders. Two major groups are the faculty and students; although they have separate roles relating to the university, both experience individual and collective issues within that setting. The purpose of this quantitative, descriptive correlational study is to explore their perceptions of issues in higher education law and policy. Students and faculty from 10 liberal arts and 10 research institutions were invited to participate in this study. A questionnaire was utilized to measure perceptions of issues in higher education law and policy in relation to free speech, gender equity, and ethnic diversity. A demographic survey also was utilized and included the stakeholder’s group (student or faculty), type of institution, gender, and ethnicity.
Universities embrace a plethora of stakeholders. Two major groups are the faculty and students; although they have separate roles relating to the university, both experience individual and collective issues within that setting. The purpose of this quantitative, descriptive correlational study is to explore their perceptions of issues in higher education law and policy. Students and faculty from 10 liberal arts and 10 research institutions were invited to participate in this study. A questionnaire was utilized to measure perceptions of issues in higher education law and policy in relation to free speech, gender equity, and ethnic diversity. A demographic survey also was utilized and included the stakeholder’s group (student or faculty), type of institution, gender, and ethnicity.
8. A la protección de la salud: Indigenous status, insurance affiliation, and prenatal care quality in Oaxaca, Mexico [2018] Online
- Collection
- Stanford University, Fisher Family Honors Program in Democracy, Development, and the Rule of Law
Despite the introduction of Seguro Popular, a universal form of health insurance, in the early 2000s, indigenous women in Mexico continue to exhibit disparately poor maternal health outcomes relative to non-indigenous women. This difference has typically been attributed to factors including poverty, rurality, and lack of care adherence, but little work has addressed the role of prenatal care quality in explaining this trend. Similarly, though Seguro Popular has assisted in equalizing the proportion of indigenous and non-indigenous women who receive prenatal care, few studies have compared the substantive quality of care provided to these two groups. Using data from ENADID 2014, this study characterizes the relationship between indigenous status, insurance affiliation, and prenatal care quality, focusing specifically on the state of Oaxaca. After developing an index of prenatal care quality consistent with both international norms and local patient care preferences, I demonstrate significantly worse prenatal care quality among indigenous women across every measure of quality. Even after controls for socioeconomic marginalization, linear and logistic regression models of prenatal care demonstrate that indigenous women received 0.642 fewer prenatal visits (p < 0.05), exhibited reduced odds of receiving prenatal care in the first trimester (OR 0.5929, p < 0.05), received 0.3515 fewer interventions over the course of pregnancy (out of a checklist of 11 essential procedures, p < 0.05), had reduced odds of receiving prenatal care from a doctor (OR 0.3969, p < 0.01), received poorer information quality of care (0.2284 points fewer on a 3-point scale, p < 0.05), and received poorer interpersonal quality of care (0.3791 points fewer on a 3-point scale, p < 0.01). Regression models stratified by indigenous status suggest that these indigenous status- based inequalities are concentrated among Seguro Popular affiliates. The signifiant correlation between indigenous status and poor care quality, independent of socioeconomic marginalization, suggests insufficient cross-cultural communication and implicit discrimination as potential sources of this quality difference. In addition to demonstrating continued indigenous care access inequality in Oaxaca even after the implementation of Seguro Popular, these results suggest discrepancies in access to quality prenatal care as a possible explanation of Mexico’s indigenous maternal health disparities.
Despite the introduction of Seguro Popular, a universal form of health insurance, in the early 2000s, indigenous women in Mexico continue to exhibit disparately poor maternal health outcomes relative to non-indigenous women. This difference has typically been attributed to factors including poverty, rurality, and lack of care adherence, but little work has addressed the role of prenatal care quality in explaining this trend. Similarly, though Seguro Popular has assisted in equalizing the proportion of indigenous and non-indigenous women who receive prenatal care, few studies have compared the substantive quality of care provided to these two groups. Using data from ENADID 2014, this study characterizes the relationship between indigenous status, insurance affiliation, and prenatal care quality, focusing specifically on the state of Oaxaca. After developing an index of prenatal care quality consistent with both international norms and local patient care preferences, I demonstrate significantly worse prenatal care quality among indigenous women across every measure of quality. Even after controls for socioeconomic marginalization, linear and logistic regression models of prenatal care demonstrate that indigenous women received 0.642 fewer prenatal visits (p < 0.05), exhibited reduced odds of receiving prenatal care in the first trimester (OR 0.5929, p < 0.05), received 0.3515 fewer interventions over the course of pregnancy (out of a checklist of 11 essential procedures, p < 0.05), had reduced odds of receiving prenatal care from a doctor (OR 0.3969, p < 0.01), received poorer information quality of care (0.2284 points fewer on a 3-point scale, p < 0.05), and received poorer interpersonal quality of care (0.3791 points fewer on a 3-point scale, p < 0.01). Regression models stratified by indigenous status suggest that these indigenous status- based inequalities are concentrated among Seguro Popular affiliates. The signifiant correlation between indigenous status and poor care quality, independent of socioeconomic marginalization, suggests insufficient cross-cultural communication and implicit discrimination as potential sources of this quality difference. In addition to demonstrating continued indigenous care access inequality in Oaxaca even after the implementation of Seguro Popular, these results suggest discrepancies in access to quality prenatal care as a possible explanation of Mexico’s indigenous maternal health disparities.
9. A Life-cycle Assessment of Canadian-produced Liquefied Natural Gas for Consumption in China [2018] Online
- Collection
- Master's Theses, Stanford Earth
Natural gas consumption has increased in recent decades due to low prices and emissions benefits over coal. The greenhouse gas (GHG) benefits of natural gas over coal require a low upstream emissions profile, in particular with low fugitive emissions of methane. Furthermore, natural gas is unlike oil in that it is highly transport-constrained. Liquefied natural gas (LNG) allows for overseas shipping but comes at significant economic and energetic costs. We worked with a Canadian liquids-rich gas producer to better understand upstream fugitive emissions and assess their efficacy of leak detection and repair (LDAR) programs. We model emissions from their operations and perform life-cycle assessment (LCA) of a hypothetical scenario where they produce 1 billion cubic feet per day of LNG in coastal British Columbia, for consumption in Shenzhen, China. We determine the life- cycle GHG and criteria air pollutant emissions associated with such a project.
We find that the LDAR surveys have resulted in decreased number of emissions points and decreased site-wide emissions. Leaks that were fixed from LDAR surveys tended to remain fixed and did not reappear. Likewise, leaks that were not fixed tended to persist and did not go away on their own, indicating that leak persistence is very high. Consequently, LDAR surveys are resulting in emissions reductions, as long as detected leaks are fixed. Repeat LDAR surveys regularly found new emission sources, even without significant site changes occurring, supporting the idea that LDAR surveys must be done regularly to find and fix new emission sources that arise from equipment failure or breakdown.
We find that Canada-to-China LNG will result in fewer life-cycle GHG emissions than the same power generated using coal in Asian markets. Studies have estimated Chinese coal power emissions to be anywhere from 868 to 975 g CO2e/kWh, nearly double our results of 408.2 to 547.9 g CO2e/kWh. Our results are lower than prior studies due to low upstream emissions and more efficient LNG production assumptions. LCA studies of LNG have focused on upstream and liquefaction stages, but our work makes it clear that total emissions are dominated by end-use emissions. When considering the climate benefits and drawbacks of LNG, it is critical to understand how the gas will be used.
Natural gas consumption has increased in recent decades due to low prices and emissions benefits over coal. The greenhouse gas (GHG) benefits of natural gas over coal require a low upstream emissions profile, in particular with low fugitive emissions of methane. Furthermore, natural gas is unlike oil in that it is highly transport-constrained. Liquefied natural gas (LNG) allows for overseas shipping but comes at significant economic and energetic costs. We worked with a Canadian liquids-rich gas producer to better understand upstream fugitive emissions and assess their efficacy of leak detection and repair (LDAR) programs. We model emissions from their operations and perform life-cycle assessment (LCA) of a hypothetical scenario where they produce 1 billion cubic feet per day of LNG in coastal British Columbia, for consumption in Shenzhen, China. We determine the life- cycle GHG and criteria air pollutant emissions associated with such a project.
We find that the LDAR surveys have resulted in decreased number of emissions points and decreased site-wide emissions. Leaks that were fixed from LDAR surveys tended to remain fixed and did not reappear. Likewise, leaks that were not fixed tended to persist and did not go away on their own, indicating that leak persistence is very high. Consequently, LDAR surveys are resulting in emissions reductions, as long as detected leaks are fixed. Repeat LDAR surveys regularly found new emission sources, even without significant site changes occurring, supporting the idea that LDAR surveys must be done regularly to find and fix new emission sources that arise from equipment failure or breakdown.
We find that Canada-to-China LNG will result in fewer life-cycle GHG emissions than the same power generated using coal in Asian markets. Studies have estimated Chinese coal power emissions to be anywhere from 868 to 975 g CO2e/kWh, nearly double our results of 408.2 to 547.9 g CO2e/kWh. Our results are lower than prior studies due to low upstream emissions and more efficient LNG production assumptions. LCA studies of LNG have focused on upstream and liquefaction stages, but our work makes it clear that total emissions are dominated by end-use emissions. When considering the climate benefits and drawbacks of LNG, it is critical to understand how the gas will be used.
10. A Literature Review Promoting Counterinsurgency Cultural Training in Virtual Reality [2018] Online
Counterinsurgency cultural training (COIN-CT) could be augmented by adapting existing 3D desktop educational modules to virtual reality (VR). The following literature review synthesizes research on VR as a medium for training, VR as a medium for perspective taking, and current COIN-CT offerings to promote future empirical studies on VR COIN-CT solutions. This paper examines how VR features such as social presence, body transfer, and embodied cognition can lead to improved learning transfer. This paper also reviews current COIN-CT offerings in depth, identifies how VR could enhance existing options, and addresses potential challenges facing widespread adoption of VR COIN-CT.
Counterinsurgency cultural training (COIN-CT) could be augmented by adapting existing 3D desktop educational modules to virtual reality (VR). The following literature review synthesizes research on VR as a medium for training, VR as a medium for perspective taking, and current COIN-CT offerings to promote future empirical studies on VR COIN-CT solutions. This paper examines how VR features such as social presence, body transfer, and embodied cognition can lead to improved learning transfer. This paper also reviews current COIN-CT offerings in depth, identifies how VR could enhance existing options, and addresses potential challenges facing widespread adoption of VR COIN-CT.
11. A National Adaptation Plan for Water Scarcity in Iran [2018] Online
- Collection
- Stanford Iran 2040 Project
Iran’s water crisis is entering a new paradigm where its impacts are becoming visible in the daily lives of millions of people. Today, the average annual water consumption in Iran is estimated to be around 96 billion cubic meters (BCM)—a figure that is about 8% higher than Iran’s total renewable water resources (89 BCM) or about 80% higher than the scarcity threshold level of the country (about 53 BCM). The practical solutions that can potentially help Iran address its formidable water crisis can be grouped into those that seek to (i) improve water productivity (e.g., modernization of irrigation, expansion of greenhouses, and optimization of crop pattern), and (ii) selectively terminate some water-intensive activities. Herein, we argue that—given the massive imbalance between sustainable supply and demand for water—the ultimate potential reductions in water use by the solutions targeting productivity will not be sufficient to change the calculus in Iran. Although modern irrigation systems can significantly save water at the farm level, their overall effectiveness in reducing water use at the basin level is modest. Furthermore, no more than half the irrigated lands (i.e., a quarter of total farmlands) in Iran are deemed suitable for such a transformation. Therefore, the amounts of water that can be saved in Iran through irrigation modernization would be too small (about 7 BCM) compared to the copious amounts of water that should be saved to sufficiently mitigate the ongoing crisis (about 44 BCM). We then demonstrate that the annual costs of adaptation to water scarcity in Iran through reduction in farming will hover around $25 billion or a maximum of 5.5% of Iran’s projected GDP in the future. Based on the presented analysis in this paper, we suggest the following:
- Agricultural production should be reduced substantially. Even in the absence of intended reduction in farming, it is likely that shortage of water and deterioration of soil will lead to an inadvertent and uncontrolled reduction in the output from the agriculture sector in the long run. To compensate for the reduced amounts of homegrown food, in rough terms, Iran will need to spend an additional $300 per person per year to import food;
- Policymakers should renounce the rhetoric of glorifying food self-sufficiency which, considering Iran’s limited natural resources and access to technology, only comes as a huge burden on the environment and future generations. Instead, the focus should be on ensuring the food security of the nation with no concern as to whence food originates. Furthermore, pronatalist population policies seeking to increase the total fertility rate (which is currently close to the replacement level) should be abandoned;
- Experts should devote their efforts to developing an effective water governance framework that encompasses a detailed spatial account of water availability and a set of fair and economically viable rules for water distribution among various stakeholders. Experts should also clearly and truthfully explain the realities of the matter to the public and policymakers and avoid populist statements (e.g., “saving both agriculture and water is possible”) or contentless arguments (e.g., “water crisis” vs. “water bankruptcy”).
Iran’s water crisis is entering a new paradigm where its impacts are becoming visible in the daily lives of millions of people. Today, the average annual water consumption in Iran is estimated to be around 96 billion cubic meters (BCM)—a figure that is about 8% higher than Iran’s total renewable water resources (89 BCM) or about 80% higher than the scarcity threshold level of the country (about 53 BCM). The practical solutions that can potentially help Iran address its formidable water crisis can be grouped into those that seek to (i) improve water productivity (e.g., modernization of irrigation, expansion of greenhouses, and optimization of crop pattern), and (ii) selectively terminate some water-intensive activities. Herein, we argue that—given the massive imbalance between sustainable supply and demand for water—the ultimate potential reductions in water use by the solutions targeting productivity will not be sufficient to change the calculus in Iran. Although modern irrigation systems can significantly save water at the farm level, their overall effectiveness in reducing water use at the basin level is modest. Furthermore, no more than half the irrigated lands (i.e., a quarter of total farmlands) in Iran are deemed suitable for such a transformation. Therefore, the amounts of water that can be saved in Iran through irrigation modernization would be too small (about 7 BCM) compared to the copious amounts of water that should be saved to sufficiently mitigate the ongoing crisis (about 44 BCM). We then demonstrate that the annual costs of adaptation to water scarcity in Iran through reduction in farming will hover around $25 billion or a maximum of 5.5% of Iran’s projected GDP in the future. Based on the presented analysis in this paper, we suggest the following:
- Agricultural production should be reduced substantially. Even in the absence of intended reduction in farming, it is likely that shortage of water and deterioration of soil will lead to an inadvertent and uncontrolled reduction in the output from the agriculture sector in the long run. To compensate for the reduced amounts of homegrown food, in rough terms, Iran will need to spend an additional $300 per person per year to import food;
- Policymakers should renounce the rhetoric of glorifying food self-sufficiency which, considering Iran’s limited natural resources and access to technology, only comes as a huge burden on the environment and future generations. Instead, the focus should be on ensuring the food security of the nation with no concern as to whence food originates. Furthermore, pronatalist population policies seeking to increase the total fertility rate (which is currently close to the replacement level) should be abandoned;
- Experts should devote their efforts to developing an effective water governance framework that encompasses a detailed spatial account of water availability and a set of fair and economically viable rules for water distribution among various stakeholders. Experts should also clearly and truthfully explain the realities of the matter to the public and policymakers and avoid populist statements (e.g., “saving both agriculture and water is possible”) or contentless arguments (e.g., “water crisis” vs. “water bankruptcy”).
12. A New Era of Personalized Politics: The 2016 Twitter Campaign [2018] Online
This study looked at personalization during the 2016 presidential election. The ubiquity of social media and the unique features of Twitter enable new forms of personalization to emerge during political campaigns. This research added to the growing body of literature in political communication by taking a multifaceted approach to personalized politics in assessing content, interactivity, and language. The findings in this study confirmed trends from previous research in that politicians are posting more content relating to traditional campaign strategies (agenda setting, mobilization, and criticism) rather than revealing personal information about themselves. However, findings also suggest that personalized communicative practices are indeed emerging on Twitter through use of interactive features and language. This multifaceted analysis allows one to draw inferences to how personalization takes form, to give insights on how political campaigning will continue to evolve on Twitter, and to discuss its implications on the democratic process.
This study looked at personalization during the 2016 presidential election. The ubiquity of social media and the unique features of Twitter enable new forms of personalization to emerge during political campaigns. This research added to the growing body of literature in political communication by taking a multifaceted approach to personalized politics in assessing content, interactivity, and language. The findings in this study confirmed trends from previous research in that politicians are posting more content relating to traditional campaign strategies (agenda setting, mobilization, and criticism) rather than revealing personal information about themselves. However, findings also suggest that personalized communicative practices are indeed emerging on Twitter through use of interactive features and language. This multifaceted analysis allows one to draw inferences to how personalization takes form, to give insights on how political campaigning will continue to evolve on Twitter, and to discuss its implications on the democratic process.
13. A New Head of the Table: Indigenous Peoples at the Forefront of UNDRIP [2018] Online
This two-part paper asks how international Human Rights documents’ design process can become more effective and inclusive in advancing indigenous human rights by adopting a design mechanism similar to that of the Fair Food Program by the Coalition of Immokalee Workers (CIW). The purpose of this essay is to advocate for indigenous peoples’ direct participation and inclusion into Indigenous Human Rights documents’ design processes as a preliminary step towards establishing, securing, and protecting the rights that are representative of their own culture, tradition, beliefs, experiences, and perspectives. This serves as a call to action that counters the United Nations’ current western Human Rights frameworks and processes, which are ineffective in that they discuss indigenous peoples without the equal representation and understanding of their lived experiences and outlooks. Through an analysis of the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP), it will pinpoint a few of the faults of contemporary Indigenous Human Rights documents and representation, suggesting that their design processes inadvertently become exclusionary to indigenous peoples. It will then present the Coalition of Immokalee Workers (CIW), a worker-based Human Rights organization, and their successful Fair Food Program as examples of possible design models to be emulated when amending the UNDRIP and drafting future Indigenous Human Rights documents.
This two-part paper asks how international Human Rights documents’ design process can become more effective and inclusive in advancing indigenous human rights by adopting a design mechanism similar to that of the Fair Food Program by the Coalition of Immokalee Workers (CIW). The purpose of this essay is to advocate for indigenous peoples’ direct participation and inclusion into Indigenous Human Rights documents’ design processes as a preliminary step towards establishing, securing, and protecting the rights that are representative of their own culture, tradition, beliefs, experiences, and perspectives. This serves as a call to action that counters the United Nations’ current western Human Rights frameworks and processes, which are ineffective in that they discuss indigenous peoples without the equal representation and understanding of their lived experiences and outlooks. Through an analysis of the United Nations Declaration on the Rights of Indigenous Peoples (UNDRIP), it will pinpoint a few of the faults of contemporary Indigenous Human Rights documents and representation, suggesting that their design processes inadvertently become exclusionary to indigenous peoples. It will then present the Coalition of Immokalee Workers (CIW), a worker-based Human Rights organization, and their successful Fair Food Program as examples of possible design models to be emulated when amending the UNDRIP and drafting future Indigenous Human Rights documents.
14. A sequence-to-sequence regression of genome-wide chromatin data through adversarial training [2018] Online
- Collection
- Undergraduate Theses, School of Engineering
An Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) reveals information about open chromatin regions, individual nucleosomes, and chromatin compaction at nucleotide resolution using only 500 to 50,000 cells. In contrast, Chromatin Immunoprecipitation sequencing (ChIP-seq) requires much more biological samples, typically millions of cells, to detect DNA regions with histone modifications. In this sense, regressing histone ChIP-seq data from less costly ATAC-seq data will help us map missing histone marks and understand epigenomic activity in a more efficient way. This paper investigates how our modified deep adversarial training approach can be used to predict ChIP-seq signal based on ATAC-seq signal. We begin by setting the performance of convolutional neural network (CNN) model as a baseline. We then introduce three modifications to the widely used adversarial network architecture. First, we modify the generator component of the adversarial network so that it takes ATAC-seq signal as input instead of random noise and generates ChIP-seq signal from the ATAC-seq signal. Second, we suggest composite objective function based on two different losses - mean squared error and adversarial loss. Third, we apply one-sided label smoothing, which is essential in stabilizing the adversarial training. The generator trained through our new adversarial training approach reports Pearson correlation of 0.562 with respect to the actual ChIP-seq signal, outperforming the CNN baseline. We also conduct qualitative analysis on how the adversarial training based on the composite objective function helps the model predict ChIP-seq peaks using ATAC-seq signal. To the best of our knowledge, this is the first attempt to tackle epigenomic signal imputation task using deep adversarial training.
An Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) reveals information about open chromatin regions, individual nucleosomes, and chromatin compaction at nucleotide resolution using only 500 to 50,000 cells. In contrast, Chromatin Immunoprecipitation sequencing (ChIP-seq) requires much more biological samples, typically millions of cells, to detect DNA regions with histone modifications. In this sense, regressing histone ChIP-seq data from less costly ATAC-seq data will help us map missing histone marks and understand epigenomic activity in a more efficient way. This paper investigates how our modified deep adversarial training approach can be used to predict ChIP-seq signal based on ATAC-seq signal. We begin by setting the performance of convolutional neural network (CNN) model as a baseline. We then introduce three modifications to the widely used adversarial network architecture. First, we modify the generator component of the adversarial network so that it takes ATAC-seq signal as input instead of random noise and generates ChIP-seq signal from the ATAC-seq signal. Second, we suggest composite objective function based on two different losses - mean squared error and adversarial loss. Third, we apply one-sided label smoothing, which is essential in stabilizing the adversarial training. The generator trained through our new adversarial training approach reports Pearson correlation of 0.562 with respect to the actual ChIP-seq signal, outperforming the CNN baseline. We also conduct qualitative analysis on how the adversarial training based on the composite objective function helps the model predict ChIP-seq peaks using ATAC-seq signal. To the best of our knowledge, this is the first attempt to tackle epigenomic signal imputation task using deep adversarial training.
15. A Smoke Removing DC-DC Converter Composed of a Seven Stage Class DE Rectifier and a Class Phi 2 Inverter [2018] Online
- Collection
- Undergraduate Theses, School of Engineering
This thesis presents the design methodology of a miniaturized, portable, and low power electrostatic precipitator (ESP) to reduce indoor air pollution (IAP) from rural cook-stoves. Decreasing the concentration of aerosol particles helps reduce the incidence of respiratory tract infections that can lead to disease and even death. We trace existing technologies and standards to combat IAP in cookstoves, design an ESP that allows precipitation at lower voltages via an electrode design that utilizes sub 5 kV voltages, and explore how rapidly pulsed converters decrease the power consumption of the circuit and increase smoke collection.
This thesis presents the design methodology of a miniaturized, portable, and low power electrostatic precipitator (ESP) to reduce indoor air pollution (IAP) from rural cook-stoves. Decreasing the concentration of aerosol particles helps reduce the incidence of respiratory tract infections that can lead to disease and even death. We trace existing technologies and standards to combat IAP in cookstoves, design an ESP that allows precipitation at lower voltages via an electrode design that utilizes sub 5 kV voltages, and explore how rapidly pulsed converters decrease the power consumption of the circuit and increase smoke collection.
16. A Spectral View of Adversarially Robust Features [2018] Online
- Collection
- Undergraduate Theses, School of Engineering
While great progress has been made in image classification using machine learning, often achieving near-human or even superhuman accuracy on image classification tasks, recent studies have found that image classification models are vulnerable to adversarial attacks: special images crafted to fool the models into mislabeling the picture. In this work, we investigate the problem of creating an adversarially robust feature: a feature f whose value at any point x cannot be changed much by perturbing x slightly. We establish strong connections between adversarially robust features and a natural spectral property of the geometry of the dataset and metric of interest. This connection can be leveraged both to provide robust features and to provide a lower bound on the robustness of any function that has significant variance across the dataset. Finally, we provide empirical evidence that the adversarially robust features yielded via this spectral approach can be fruitfully leveraged to learn a robust (and accurate) model.
While great progress has been made in image classification using machine learning, often achieving near-human or even superhuman accuracy on image classification tasks, recent studies have found that image classification models are vulnerable to adversarial attacks: special images crafted to fool the models into mislabeling the picture. In this work, we investigate the problem of creating an adversarially robust feature: a feature f whose value at any point x cannot be changed much by perturbing x slightly. We establish strong connections between adversarially robust features and a natural spectral property of the geometry of the dataset and metric of interest. This connection can be leveraged both to provide robust features and to provide a lower bound on the robustness of any function that has significant variance across the dataset. Finally, we provide empirical evidence that the adversarially robust features yielded via this spectral approach can be fruitfully leveraged to learn a robust (and accurate) model.
17. "A Stain on Our Souls:" The Darfur Genocide During the Obama Presidency [2018] Online
Since 2003, the Sudanese government and its Arab militia proxies have conducted a genocide against Africans in Darfur, killing roughly 500,000 people and displacing 2.7 million. Public outcry compelled President George W. Bush to take diplomatic measures to end the atrocities, though they achieved little success. In 2007, then-Senator Barack Obama included Darfur on his presidential platform and denounced the genocide as a “stain on our souls.” Nevertheless, during his presidency, Obama not only failed to address the genocide, but also lifted sanctions that had been imposed on Khartoum for its criminal activities in Darfur. This thesis examines why the Obama Administration’s foreign policies in relation to Darfur were so weak. In particular, I focus on four main factors that constrained U.S. action in the region: lack of political salience, South Sudan's creation and subsequent implosion, humanitarian crises elsewhere, and China's and Russia's economic interests in Sudan. By understanding these policy constraints, we might learn how to end this long and violent genocide, as well as other humanitarian conflicts in areas with little national strategic import.
Since 2003, the Sudanese government and its Arab militia proxies have conducted a genocide against Africans in Darfur, killing roughly 500,000 people and displacing 2.7 million. Public outcry compelled President George W. Bush to take diplomatic measures to end the atrocities, though they achieved little success. In 2007, then-Senator Barack Obama included Darfur on his presidential platform and denounced the genocide as a “stain on our souls.” Nevertheless, during his presidency, Obama not only failed to address the genocide, but also lifted sanctions that had been imposed on Khartoum for its criminal activities in Darfur. This thesis examines why the Obama Administration’s foreign policies in relation to Darfur were so weak. In particular, I focus on four main factors that constrained U.S. action in the region: lack of political salience, South Sudan's creation and subsequent implosion, humanitarian crises elsewhere, and China's and Russia's economic interests in Sudan. By understanding these policy constraints, we might learn how to end this long and violent genocide, as well as other humanitarian conflicts in areas with little national strategic import.
18. A Transnational Encounter of Cosmopolitan Fantasies: Directing The World of Extreme Happiness at Stanford University [2018] Online
- Collection
- Stanford University, Department of Theater and Performance Studies, Undergraduate Honors Theses
This dramaturgical thesis interrogates the transnational dimension of staging Frances Ya-Chu Cowhig's play 'The World of Extreme Happiness,' a play about a factory girl in Shenzhen China, at Stanford University, an elite neoliberal university down the road from Silicon Valley. Specifically, we argue that, as Western cosmopolitan subjects, the audience encounter with the play is that of cultural consumption, projecting a fantasized timeline of modernity onto the protagonist's journey, with her rural home seen as 'backwards' and 'local' and the Western city as 'progressive' and 'cosmopolitan.' Consequently, this thesis examines how a production of this play can disrupt such an imagination by invoking the ways the protagonist is 'modern' and cosmopolitan, while still confronting the transnational power dynamics present in the relationship between audience and protagonist. We propose theatrical devices, particularly in and around 'gazing,' to performatively subvert these imagined global hierarchies among a Western cosmopolitan audience.
This dramaturgical thesis interrogates the transnational dimension of staging Frances Ya-Chu Cowhig's play 'The World of Extreme Happiness,' a play about a factory girl in Shenzhen China, at Stanford University, an elite neoliberal university down the road from Silicon Valley. Specifically, we argue that, as Western cosmopolitan subjects, the audience encounter with the play is that of cultural consumption, projecting a fantasized timeline of modernity onto the protagonist's journey, with her rural home seen as 'backwards' and 'local' and the Western city as 'progressive' and 'cosmopolitan.' Consequently, this thesis examines how a production of this play can disrupt such an imagination by invoking the ways the protagonist is 'modern' and cosmopolitan, while still confronting the transnational power dynamics present in the relationship between audience and protagonist. We propose theatrical devices, particularly in and around 'gazing,' to performatively subvert these imagined global hierarchies among a Western cosmopolitan audience.
19. Absorbing optical antennas [electronic resource] : applications in nanophotonics and combustion [2018] Online
- Book
- 1 online resource.
The promise of optical antennas is the ability to tame the light to behave in ways not achievable using traditional optical components. For example, our results here demonstrate that a careful engineering of optical antennas allow the strong, even perfect, absorption of light in ultra-thin geometries, i.e., geometries much thinner than the wavelength of light. Enabled by geometry-sensitive antenna resonances, this absorption behavior can also be realized for a broad selection of colors. A detailed theoretical analysis of the observed perfect absorption phenomenon reveals the role of incoherently interacting degenerate electric and magnetic resonances in overcoming the well-known absorption limit for infinitesimally thin films. With another set of experiments, we show that strongly absorbed optical energy in aluminum nanoantennas can be used to heat them efficiently above their melting temperature and stimulate an explosive exothermic oxidation reaction called melt-dispersion mechanism. Importantly, we see that engineering the specific geometry of the constituent particles allows an unprecedented control of aluminum ignition, both spectrally and spatially, through the fine tuning of the optical antenna resonances.
The promise of optical antennas is the ability to tame the light to behave in ways not achievable using traditional optical components. For example, our results here demonstrate that a careful engineering of optical antennas allow the strong, even perfect, absorption of light in ultra-thin geometries, i.e., geometries much thinner than the wavelength of light. Enabled by geometry-sensitive antenna resonances, this absorption behavior can also be realized for a broad selection of colors. A detailed theoretical analysis of the observed perfect absorption phenomenon reveals the role of incoherently interacting degenerate electric and magnetic resonances in overcoming the well-known absorption limit for infinitesimally thin films. With another set of experiments, we show that strongly absorbed optical energy in aluminum nanoantennas can be used to heat them efficiently above their melting temperature and stimulate an explosive exothermic oxidation reaction called melt-dispersion mechanism. Importantly, we see that engineering the specific geometry of the constituent particles allows an unprecedented control of aluminum ignition, both spectrally and spatially, through the fine tuning of the optical antenna resonances.
20. Accelerating oil-water subsurface flow simulation through reduced-order modeling and advances in nonlinear analysis [2018] Online
- Book
- 1 online resource.
Reservoir simulation is an important tool for understanding and predicting subsurface flow and reservoir performance. In applications such as production optimization and history matching, thousands of simulation runs may be required. Therefore, proxy methods that can provide approximate solutions in much shorter times can be very useful. Reduced-order modeling (ROM) methods are a particular type of proxy procedure that entail a reduction of the number of unknown variables in the nonlinear equations. This dissertation focuses on two of the most promising proper orthogonal decomposition (POD)-based ROM methods, POD-TPWL and POD-DEIM. A separate (non-ROM) technique to accelerate nonlinear convergence for oil-water problems is presented in the appendix.
Reservoir simulation is an important tool for understanding and predicting subsurface flow and reservoir performance. In applications such as production optimization and history matching, thousands of simulation runs may be required. Therefore, proxy methods that can provide approximate solutions in much shorter times can be very useful. Reduced-order modeling (ROM) methods are a particular type of proxy procedure that entail a reduction of the number of unknown variables in the nonlinear equations. This dissertation focuses on two of the most promising proper orthogonal decomposition (POD)-based ROM methods, POD-TPWL and POD-DEIM. A separate (non-ROM) technique to accelerate nonlinear convergence for oil-water problems is presented in the appendix.
