Browsing by Author "Zhang, Yang"

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    Accepted Tutorials at The Web Conference 2022
    Tommasini, Riccardo; Basu Roy, Senjuti; Wang, Xuan; Wang, Hongwei; Ji, Heng; Han, Jiawei; Nakov, Preslav; Da San Martino, Giovanni; Alam, Firoj; Schedl, Markus; Lex, Elisabeth; Bharadwaj, Akash; Cormode, Graham; Dojchinovski, Milan; Forberg, Jan; Frey, Johannes; Bonte, Pieter; Balduini, Marco; Belcao, Matteo; Della Valle, Emanuele; Yu, Junliang; Yin, Hongzhi; Chen, Tong; Liu, Haochen; Wang, Yiqi; Fan, Wenqi; Liu, Xiaorui; Dacon, Jamell; Lye, Lingjuan; Tang, Jiliang; Gionis, Aristides; Neumann, Stefan; Ordozgoiti, Bruno; Razniewski, Simon; Arnaout, Hiba; Ghosh, Shrestha; Suchanek, Fabian; Wu, Lingfei; Chen, Yu; Li, Yunyao; Liu, Bang; Ilievski, Filip; Garijo, Daniel; Chalupsky, Hans; Szekely, Pedro; Kanellos, Ilias; Sacharidis, Dimitris; Vergoulis, Thanasis; Choudhary, Nurendra; Rao, Nikhil; Subbian, Karthik; Sengamedu, Srinivasan; Reddy, Chandan; Victor, Friedhelm; Haslhofer, Bernhard; Katsogiannis- Meimarakis, George; Koutrika, Georgia; Jin, Shengmin; Koutra, Danai; Zafarani, Reza; Tsvetkov, Yulia; Balachandran, Vidhisha; Kumar, Sachin; Zhao, Xiangyu; Chen, Bo; Guo, Huifeng; Wang, Yejing; Tang, Ruiming; Zhang, Yang; Wang, Wenjie; Wu, Peng; Feng, Fuli; He, Xiangnan (ACM, 2022-04-25)
    This paper summarizes the content of the 20 tutorials that have been given at The Web Conference 2022: 85% of these tutorials are lecture style, and 15% of these are hands on.
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    Advancements for the Numerical Simulation of Free Fall Penetrometers and the Analysis of Wind Erosion of Sands
    Zambrano Cruzatty, Luis Eduardo (Virginia Tech, 2021-08-27)
    The coastal population is growing, putting extra stress on coastal sediments and protection features, such as beach dunes. Moreover, global warming will increase the frequency of storms, and coastal dunes and other defense infrastructure will be subjected to increased erosion and scouring, endangering the people they are meant to protect. Understanding soil dynamics and fluid interaction is crucial to predict the effects of sand erosion. In particular, the study of wind erosion of sands in coastal dunes is essential due to the protective role these earthen structures have during storm events. One of the challenges about predicting wind erosion in coastal dunes is its extended spatial scale and the associated economic and logistics costs of sampling and characterizing the sediments. Because of this, in-situ testing for sediment characterization is essential. In particular, the usage of free-fall penetrometers (FFP) is appealing due to their portability and robustness. The sediment properties obtained with this type of testing can later be used to assess wind erosion susceptibility by determining, for example, the wind velocity to initiate the erosion process. FFP testing involves dropping an instrumented probe that impacts the soil and measures the kinematics or kinetics during the penetration process. For example, deceleration measurements are used to compute an equivalent quasi-static failure, which is not in line with the dynamic process characteristic of FFP testing. This preassumed failure mechanism is used to back-calculate the sand's geomechanical properties. However, soil behavior is highly complex under rapid loading, and incorporating this behavior into FFP sediment characterization models is challenging. Advanced numerical modeling can improve the understanding of the physics behind FFP testing. This thesis presents various advancements in numerical modeling and erosion models to bridge FFP in-situ testing with predicting the initiation of wind erosion of sands. First, improvements oriented to the Material Point Method (MPM) for modeling in-situ FFP testing are proposed. The numerical results show that the simulation of FFP deployment in sands is affected by strain localization and highlight the importance of considering constitutive models sensitive to different loading rates. Because of the importance of rate effects in soil behavior, the second aspect of this thesis proposes a novel consistency framework. Two constitutive models are adapted to study strain-rate sensitive non-cohesive materials: i) a strain-softening Mohr-Coulomb, and ii) a NorSand model. In addition to increased strength, the proposed framework captures increased dilatation, an early peak deviatoric stress, and relaxation. Finally, a novel sand erosion model is derived using a continuum approximation and limit equilibrium analysis. The erosion law considers geotechnical parameters, the effects of slope, and moisture suction, in a combined manner. The proposed model is theoretically consistent with existing expressions in the literature. It covers a wide range of environmental and geometrical conditions and helps to reconcile the results from FFP testing with the prediction of the initiation of wind erosion. The model was validated in a wind tunnel and is demonstrated to be a viable alternative for predicting sand erosion initiation. This thesis opens up new research prospects, such as improving the soil characterization models or the direct prediction of sand erosion using rapid, reliable, and efficient in-situ testing methods.
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    Analysis of Post-Sandy Single-Family Housing Market in Staten Island, New York
    Borate, Aishwarya (Virginia Tech, 2018-11-13)
    Recent hurricanes have made it clear that housing is the single greatest component of all losses in terms of economic value and buildings damaged. Housing damage resulting from floods has increased in the United States, despite local, state and federal encouragement to mitigate flood hazards and regulate development in flood-prone areas (Atreya, 2013). The two primary causes of these increased costs are: (1) a rise in the occurrence and strength of the extreme weather events, and (2) increased development and value of property in physically vulnerable areas. The overlap of the above two factors resulted in tremendous losses of property in Staten Island and other coastal communities along the Atlantic Coast. Hurricane Sandy was a reminder of how vulnerable such areas could be. After hurricane Sandy, damaged properties experienced higher than usual housing sales and changed property values. This research, seeks to improve the current state of knowledge about housing market following a major disaster through examining single-family housing sales and prices in Staten Island, New York. The housing price recovery rate was much slower for the properties that sustained damage, and the impacts lasted for at least four years after the storm. Researchers studying housing recovery have utilized a variety of indicators like financial characteristics, government policies, social parameters, damage, housing characteristics, etc. to capture the dimensions of recovery. In Sandy's case damage was the major influencing parameter, and it completely changed the housing dynamics of the affected coastal regions. Housing market, in terms of damage, restoration, and recovery, is a fundamental indicator of disaster resilience. Every community is different and so are the effects of disasters on residential markets. This study clearly highlights this point and underscores the importance of using contextual methods and data sets in conducting the research.
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    An Analysis of Social Vulnerability to Natural Hazards in Nepal Using a Modified Social Vulnerability Index
    Aksha, Sanam K.; Juran, Luke; Resler, Lynn M.; Zhang, Yang (2018-11-16)
    Social vulnerability influences the ability to prepare for, respond to, and recover from disasters. The identification of vulnerable populations and factors that contribute to their vulnerability are crucial for effective disaster risk reduction. Nepal exhibits multihazard risk and has experienced socioeconomic and political upheaval in recent decades, further increasing susceptibility to hazards. However, we still know little regarding social vulnerability in Nepal. Here, we investigate social vulnerability in Nepal by adapting Social Vulnerability Index (SoVI) methods to the Nepali context. Variables such as caste, and populations who cannot speak/understand Nepali were added to reflect the essence of the Nepali context. Using principal component analysis, 39 variables were reduced to seven factors that explained 63.02% of variance in the data. Factor scores were summarized to calculate final SoVI scores. The highest levels of social vulnerability are concentrated in the central and western Mountain, western Hill, and central and eastern Tarai regions of Nepal, while the least vulnerable areas are in the central and eastern Hill regions. These findings, supplemented with smaller-scale analyses, have the potential to assist village officers, policymakers, and emergency managers in the development of more effective and geographically targeted disaster management programs.
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    Architecture After Forced Migration
    Pacheco Aviles, Damiana Isabel (Virginia Tech, 2018-06-07)
    Communities affected by climate impacts, political or cultural conflicts and rapid demographic shifts are the most vulnerable to the effects of poverty, disease and communal violence. Addressing their needs through appropriate architectural responses can help them to recover social, economic and environmental well-being. This thesis defines strategies to address the challenges involved in the design of spaces after three causes of forced migration: natural disaster, conflict and urban development. The methodology is based on literature review which served as theoretical background to work in three design competitions related to shelter after natural disasters, refugee camps and slums. The need to provide accommodation after a natural disaster is essential. Therefore, a shelter that can be transported and deployed quickly and effectively, and that contemplates the uniqueness and complexity of the event, is studied in this thesis. Refugee camps have become the protective and safe place that provide shelter, food and health safety to all kinds of survivors and refugees. Due to the complexity of the problems related to this forced migration situation, the presence of refugee camps tends to be longer than the expected. Therefore, a design that contemplates this duality of time and that addresses peoples' needs and rights is part of this research. Slums are often related to deprivation and socio-spatial exclusion and due to the lack of security of tenure, they are vulnerable to evictions caused by redevelopment pressures, gentrification processes and episodes of ethnic cleansing. Therefore, a neighborhood's transformation with cohesive public spaces and incremental housing prototypes is proposed in this thesis. Through the study of architectural responses to natural disaster, refugee camps and slums design considerations related to the site, the culture and the urban context are established as guidelines. In addition, a time-based design strategy, a dual design approach and a multiple scales design strategy are defined as essential to give an architectural response to forced-displaced communities.
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    Assessing vulnerability and multi-hazard risk in the Nepal Himalaya
    Aksha, Sanam Kumar (Virginia Tech, 2018-11-15)
    Communities around the world are encountering unprecedented rates of change due to population growth, land use change, development, and increased social vulnerability to natural hazards. Understanding how physical processes and human vulnerability to natural hazards interact is a primary objective of researchers, policy makers, and disaster risk reduction practitioners in order to combat increases in natural hazard frequency and intensity. Nepal, a landlocked mountainous country spanning the central Himalayan region, has about 28 million inhabitants in 147,181 square kilometers. Nepal is exposed to a multitude of natural hazards, requiring individuals and communities to interact with and make decisions on risk acceptability on a day-to-day basis. In many cases, Nepal's geographic location, available resources (human, economic, and capital), and limited government capacity coalesce to turn natural hazards into disasters, resulting damaged infrastructure, economic disruptions, and death. This dissertation evaluates the geographic distribution of natural hazard mortality, quantifies social vulnerability to natural hazards, and models multi-hazard risk in the data deficient environment of Nepal. Chapter 1 conceptualizes relevant terms such as natural hazards, disaster, vulnerability, and risk before discussing the challenges associated with multi-hazard risk assessment in Nepal. Chapter 2 evaluates the spatial and temporal distribution of natural hazard mortalities at the village level using a publicly available disaster database. Results reveal that landslides were the deadliest disasters between 1971-2011. Chapter 3 identifies major social factors and processes that contribute to the vulnerability of individuals and communities using census data. Adapting the Social Vulnerability Index (SoVI) method developed for the US context, this chapter investigates the spatial distribution and clustering of various social vulnerabilities across the country. 'Renter and Occupation', 'Poverty and Poor Infrastructure', and 'Favorable Social Conditions' are three major components that influence social vulnerability in Nepal. Results indicate an interesting regional difference: the eastern and central Tarai are more vulnerable than western Tarai, whereas the eastern Hills and Mountains are less vulnerable than western Hills and Mountains. In Chapter 4, a model of risk from multiple natural hazards in the city of Dharan, Nepal, is presented. Freely available geospatial data in combination with socio-economic data collected from local government and secondary sources are used. Multi-hazard risk assessment is data intensive and requires considerable financial and human resources, which are lacking in Nepal. Results show that geospatial modeling techniques can be used to fill the gap and assist local officers and emergency managers in risk management. Cumulatively, this work offers new insights on natural hazards, vulnerability, risk, the use of geospatial technologies, and their inter-relationships. Research findings advance scholarly understandings of multi-hazard risk in general and particularly in the Nepali context. Additionally, this work is valuable to disaster practitioners who seek to implement more effective disaster risk reduction programs and policies.
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    Climate Change Relocation as an Adaptation Strategy: from Taboo to Opportunity
    Bukvic, Anamaria (Virginia Tech, 2012-07-19)
    Relocation is often taboo among policy makers and planners due to its political, social, and ethical connotations, and although increasingly mentioned as one of the potential climate change adaptation strategies, it mostly adheres to rhetoric with limited discussion of its actual implementation. Scientific study and observation indicate the imminence of climate change impacts, many of which may exceed the adaptive capacity of vulnerability hotspots. Therefore, it is imperative to reassess this response option in the light of its past negative reputation, the success of current initiatives, and decision makers' evolving perception of relocation as an adaptation option. The main objective of this dissertation research is to determine the need for, interest in, and prospects for community relocations as an adaptation option; explore ways to address limitations associated with this alternative, and identify opportunities that could emerge from the relocation process. This study reviews experiences from the past and current relocation efforts and gauges the current level of interest in and support for this adaptation option among policy makers and planners. It also provides conceptual models - the relocation scenario, its digitalized simulation, the Climate Change Relocation Leaf, and the Relocation Suitability Index - designed to help communities, policy makers and planners explore this alternative. The research commences with a comprehensive literature review of theoretical knowledge, past experiences, current case studies, and the existing state of institutional, political, and social perspectives related to climate change migration and relocation. It continues with a comparative content analysis of climate change adaptation plans to elucidate the relocation rhetoric utilized in the selected texts at what frequency and in what context. Next, the study represents the climate change relocation models and a scenario developed to engage decision-makers and stakeholders in assessing the need for and possibility of relocation. Lastly, the project concludes with the development of a conceptual and tabular framework for the Relocation Suitability Index and subsequent simulation designed to compare possible relocation host sites systematically based on their absorption capacity.
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    Comparative Assessment of Sound Generated Using Laser-Induced Plasma
    Szőke, Máté; Bahr, Christopher; Cattafesta, Louis; Rossignol, Karl-Stéphane; Ura, Hiroki; Zhang, Yang; Zigunov, Fernando (2021-08-10)
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    Do Qualified Allocation Plans Influence Developers' LIHTC Siting Decisions: The Case of Access to High-Performing Schools
    Shanholtz, Spencer A. (Virginia Tech, 2016-12-19)
    The study analyzed variation among low income housing tax credit (LIHTC) allocation policies as outlined in state qualified action plans (QAP) and their impacts on the siting patterns of LIHTC properties in proximity to high performing schools. The study was performed nationwide across 37 states and controlled for factors relevant to the development location decision using census-based population characteristics and LIHTC property attributes. The purpose was to determine the effectiveness of LIHTC QAP allocation policies in motivating developers to site their developments near high-performing schools. QAPs typically use points when awarding tax credits competitively, and this study focused on points awarded for (1) access to high quality schools, (2) access to any schools, and (3) location in areas with attributes expected to correlate strongly with high quality schools. Multi-level linear modeling estimated that points for access to any schools had a significant and positive effect on location in a high performing school's catchment area, but other allocation policy variables had no significant effects. The findings inform readers about the ability of current allocation policy to influence developer actions, and discussion centers on policy recommendations and the need for further research.
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    Environmental Risks, the Leverage of Scientific Information and Data, and Mediated Communication
    Seo, Hye-Jeong (Virginia Tech, 2024-05-28)
    This dissertation addresses the complex challenge of communicating knowledge about environmental risks from toxic chemicals. Modern environmental risks are often invisible and technically complex, making the management of these risks highly dependent on data and information. Reliance on risk knowledge necessitates effective dissemination and communication by government agencies, yet the public's engagement with this information remains unclear due to limited real-world studies. This dissertation is comprised of three standalone papers bridging this gap. Each focuses on different aspects of risk knowledge communication using news dialogues as data sources. The first paper investigates the communication of location-specific risk information through a case study of the Radford Army Ammunition Plant (RAAP). Using content analysis and logistic regression, the study examines how scientific information about local environmental issues is presented in news articles and what factors influence its inclusion. Findings highlight the varying capacities among different stakeholder groups to access and utilize scientific information, underscoring the need for governmental and research support for less-resourced groups. The second paper explores chemical-specific risk knowledge, focusing on the environmental risks associated with per- and polyfluoroalkyl substances (PFAS). Employing a structural topic model (STM) and multinomial logistic regression, the study assesses the impact of the United States Environmental Protection Agency (US EPA)'s Draft Toxicity Assessment for GenX, one of the PFAS chemicals, on news topics. Results indicate that the influence of new risk knowledge on news topics varies depending on community context, with significant impacts observed when communities are ready for governmental action or legislation using the new assessment. The third paper examines the use of the US EPA's Toxics Release Inventory (TRI) database in news media. Through exploratory analysis, it reveals how different stakeholders use TRI data to make claims about environmental risks, highlighting that environmental organizations are primary users who often reconstruct TRI data to make it more relevant to the public. This suggests their potential role as intermediaries in risk knowledge communication. This dissertation provides empirical evidence of the limited news coverage of environmental risk knowledge, the dominance of government sources, and the significant role of intermediary groups. The findings suggest policy implications for government agencies and other organizations, highlighting the need to improve the conveyance and communication of risk knowledge. Recommendations include providing more contextual information and training for communities and intermediary groups on interpreting and utilizing risk data and information. These aim to bolster public comprehension and responsiveness to environmental risks, thereby protecting public safety and health.
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    Estimating Post-Construction Costs of a Changing Urban Stormwater Program
    Licher, Monica Katherine (Virginia Tech, 2016-07-05)
    Degradation of the nation's waters continues to be a problem and urban runoff is a large contributor to it. New stormwater management policies stress the importance of using stormwater control practices that reduce the quantity and improve the quality of stormwater runoff. The new approaches tend to emphasize small-scale, on-site practices over large scale. Yet to achieve water quality benefits, stormwater control practices must be maintained over time. Maintenance costs of these facilities, however, are poorly understood. A case study of five municipalities around the United States is used to estimate inspection and enforcement costs for each case site. Maintenance activities and costs were collected at the case sites for the following stormwater controls: dry ponds, wet ponds, wetlands, bioretention facilities, sand filters, and infiltration trenches. Cost estimates indicate that inspection and enforcement is not influenced by type. Maintenance cost estimates change depending on the BMP type. Estimated annual post-construction costs applied to a hypothetical 1,000-acre indicate that moving from large-scale to small-scale stormwater controls has a large impact in terms of financial obligation.
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    Flood Modeling and Community Engagement in Giles County, Virginia
    Kahl, Alexandra Claire (Virginia Tech, 2020-06-04)
    Evaluating and educating communities on their flood risks is an integral part of adapting to climate change and more extreme precipitation patterns. Low-income communities are often the most affected by in-land floods. They are more likely to live in floodplains and have less socioeconomic mobility. This thesis takes a two-pronged approach to evaluating flood risk. First, a flood risk model that identifies areas of high runoff in Giles County, Virginia was developed. The model accounts for land cover, soil type and elevation. The soil retention layer and Digital Elevation Model (DEM) produced a cell by cell layer of runoff. Storm data was collected from the NEXRAD program and integrated into the runoff layer. Countywide maps of low, moderate and high risk were produced. Semi structured interviews were then conducted to gauge the usability of the maps within high risk areas. Interview feedback was transcribed and coded for analysis. Themes identified throughout the interviews, were used to make adjustments to the model and maps. This experience suggests that combining technical analysis and community engagement can create a more accurate depiction of flood risk that is meaningful to those most affected. This paper also suggests that evaluating riverine flooding based on the most severe, recent storm yields a more accurate and impactful tool than previous flood modeling methods. This work takes flood modeling a step farther by receiving community input and shows that models are only as useful as they are meaningful to the most impacted communities.
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    From Ideas to Actions: Hazard Mitigation Policy Adoption—Analysis of Floodplain Property Buyout Program
    Wang, Qiong (Virginia Tech, 2023-08-23)
    Climate change is exerting a profound influence on natural hazards, resulting in increased frequency, intensity, and altered patterns of extreme weather events. These changes pose significant risks to vulnerable populations worldwide. Consequently, it is imperative to adopt hazard mitigation policies to address the impacts of climate change on natural hazards and communities. The adoption of such policies is a complex and dynamic process that requires a thorough understanding of the key factors influencing policy adoption. The United States has experienced a rise in the severity and frequency of floods, necessitating the implementation of comprehensive flood mitigation policies. These policies aim to protect vulnerable communities, safeguard critical infrastructure, and reduce the economic and human costs associated with these natural disasters. Among the various flood mitigation strategies, floodplain property buyout programs have garnered attention. However, there is limited research that examines the factors influencing the adoption of buyout programs at the local government level from a government perspective. This dissertation provides a comprehensive analysis of the adoption process of floodplain property buyout programs at the local level in the United States. The study employs a mixed methods approach to examine the mechanism behind policy adoption and identify the key factors that influence this process. Chapter 1 lays the foundation for the research by defining relevant terms and outlining the characteristics of floodplain property buyout programs in the U.S. Chapter 2 presents a theoretical framework that enhances our understanding of hazard mitigation policy adoption at the local level. The framework is exemplified through case studies of property buyout programs in North Carolina and New Jersey. The case studies conducted in these states offer compelling evidence that supports the proposed framework, which encompasses five-factor categories: hazard problem, social context, institutional capacity, cross-sector collaboration, and policy diffusion. Notably, institutional capacity plays a crucial role in buyout adoption, encompassing individual, organizational, and system capacity. These factors influence the uptake of buyouts and contribute to their success or failure. This exercise gives us valuable insights into the buyout decision making process and suggests avenues for research in the subsequent chapters. Chapter 3 conducts a quantitative analysis to validate the hazard mitigation policy adoption framework. Specifically, it focuses on investigating the factors that influence the adoption of Federal Emergency Management Agency (FEMA) property buyout programs by local governments in Virginia counties. Utilizing logistic regression models and a survey dataset collected from local floodplain managers in the Commonwealth of Virginia, the study reveals that floodplain managers' perception of repetitive flood loss and economic spillovers in neighboring areas significantly impact the adoption of buyout programs. In Chapter 4, we conduct a qualitative approach to delve into the decision-making dynamics in the adoption of floodplain property buyout programs from a government perspective in Virginia. Through semi-structured interviews with 12 experts representing various stakeholders involved in floodplain management, this study demonstrates the variations in the adoption processes among different local governments. The findings underscore the importance of leadership, community population size, floodplain managers' perception of repetitive flood loss, organizational staff capacity, and tax revenue considerations in shaping buyout decisions. It highlights the need for local leadership commitment, empowerment of floodplain managers, and comprehensive approaches to address challenges faced by small communities. The research provides practical guidance to enhance flood risk management practices and promote resilient and sustainable communities. In conclusion, this dissertation contributes to the understanding of hazard mitigation policy adoption at the local level by proposing a theoretical framework and providing empirical evidence through case studies, surveys, and interviews. The findings emphasize the importance of various factors, such as hazard problem, social context, institutional capacity, and policy diffusion, in shaping buyout policy adoption. The implications of this research extend to policymakers, practitioners, and researchers, providing insights into the motivations, obstacles, and strategies surrounding the adoption and implementation of hazard mitigation policies. By considering these factors and employing comprehensive approaches, communities can enhance their resilience and effectively mitigate the impacts of natural hazards.
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    The Impacts of Climate Change on Rice Production and Small Farmers' Adaptation: A Case of Guyana
    Mahdu, Omchand (Virginia Tech, 2019-04-22)
    Prior research has concluded that climate change is having an overall negative impact on rice production worldwide. The vast majority of climate change impacts on rice production result from fluctuations in precipitation and temperature, which lead to flooding, water scarcity, and increases in insects and pests, diseases, and weeds. As a small developing country, Guyana is highly vulnerable to climate change despite its insignificant contribution to global warming. Guyana heavily relies on rice cultivation for food, employment, and export earnings. While generally increasing, rice yields have fluctuated over the last two decades. For example, in 2016, rice yields declined by 12.7 percent due to a drought. This dissertation explores the relationship between fluctuating yields and climate change, and how farmers are adapting. Of particular importance are the impacts of climate change on small farmers (those cultivating less than 4.45 hectares or 11 acres) and their ability to successfully adapt. Small farmers are especially vulnerable to a changing climate because they often lack the necessary knowledge, support, and resources to effectively respond and adapt. Given the large percentage of rice farmers engaging in small-scale production in Guyana, this study investigates the impacts of climate variability on rice production and the extent to which the production and productivity of small farmers are affected. It also identifies the coping strategies small farmers employ to combat the effects of climate change and the extent to which these strategies are successful. Given that climate change is expected to vary across different regions of the world, the first aim of this study is to show how the climate in Guyana has changed. At the country level, evidence from descriptive statistics, a linear trend model, and a two-sample t-test shows that minimum and maximum temperatures have increased over the last 111 years. The aggregate data is less clear on changes in precipitation over the last 111 years. However, analysis of farm-level data provides strong evidence of shifts in rainfall patterns. Among 189 small farmers interviewed, 182 (96.3%) perceived changes in rainfall patterns, 170 (89.9%) perceived changes in temperature, 169 (89.4%) perceived changes in extreme weather events, 185 (97.9%) perceived changes in insects and pests, 73 (38.6%) perceived changes in diseases, and 168 (88.9%) perceived changes in weeds. Changes in precipitation have included an increase in intensity and out of season rainfall, which has impacted harvesting due to poor dams, wet fields, and the lodging of plants. The primary responses farmers have adopted include adjusting planting dates based on water availability and the cultivation of different rice varieties. Changes in temperature have resulted in hotter days, accelerating the evaporation of water from fields. In response, farmers replenish water in their fields, when available. Excess rainfall and resulting flooding, drought, and heavy winds have been the primary extreme weather events observed. Excess rainfall and associated flooding submerges, uproots, and/or kills young plants. The lodging of plants due to heavy winds and flooding has been the main impact. In response to flooding, farmers have pumped water out of their fields. There is very little that farmers can do in response to heavy winds. The primary change in insects and pests reported by farmers has been an increase in paddy bug infestations, which cause damage to the grains resulting in lower quality and quantity at harvest. As a result, farmers are engaging in more preventative spraying. An increase in brown spot disease was also reported. Brown spots are primarily found on the leaves, damaging and/or stunting the growth of the plants by reducing the amount of food they manufacture through photosynthesis. Farmers have responded by engaging in preventative spraying and the rotation of fungicides. Increases in red rice and duckweed have been the major changes in weeds observed. Both weeds compete with rice for space, sunlight, nutrients, and water. Additionally, red rice reduces the quality and by extension the price farmers receive. Farmers are responding by spraying more herbicide and using a contact chemical to burn red rice. Multivariate analysis of farm-level data found that land tenure, tractor ownership, membership in an agricultural organization(s), secondary non-agricultural income, and farms located in regions two and four have positive correlations with annual yields. Perceived changes in rainfall, farm size, livestock ownership, participation in rice extension training, and household members help with rice farming were found to have negative correlations with annual yields. Policy recommendations to improve rice production and farmers' resilience include improving research and development capacity; tax exemption for agricultural inputs and equipment; improving extension services; improving the management of irrigation systems and water resources; enhanced access to credit, insurance, and subsidies; improving weather forecasting and climate monitoring; and improving the management of drainage infrastructure. The analytical framework used in this research produced a rich dataset and interesting results that are important to our understanding of farm-level impacts and responses to climate change. As such, it may prove useful for studying climate change impacts in other developing countries that have similar characteristics and face similar risks from climate change as Guyana.
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    Meeting the Self and the Other: Intercultural Learning During a Faculty-led Short-term Service-Learning Course to Belize
    Boggs-Parker, Carmen Elana (Virginia Tech, 2021-04-07)
    Cross-cultural knowledge and intercultural competence are highly valued qualities for 21st-century American college and university graduates, as these institutions endeavor to prepare students to live and work in an increasingly multicultural society. This task offers both a challenge and an opportunity for educators to design mechanisms to increase the global awareness and intercultural development of their student participants. The challenge is to create intentional learning experiences that avoid the pitfalls of perpetuating stereotypes and reproducing inequitable social relations. Faculty-led international travel courses provide an opportunity for program leaders to develop intercultural development curricula that are ethical, engaging, economically and environmentally sustainable, and pedagogically sound. This study examined how participants in a faculty-led short-term global service-learning course to Belize experienced and perceived cultural difference and how that professor attended to and sought to address cultural difference and issues of power, positionality, and privilege during that program. This study followed a convergent parallel mixed method design in which I collected and analyzed qualitative and quantitative data concurrently. This combination of methods yielded a more complete understanding of the learning process and intercultural learning outcomes of the student participants, as well as the pedagogical and programmatic features that encouraged the growth of intercultural competencies in each. The quantitative findings of this study indicated little change in the competency levels of the program's participants, whereas the qualitative data suggested that the Belize travel course students had experienced notable gains in cultural self-awareness and were better able to identify relevant cultural differences. Participants singled-out the immersive quality of the experience, the variety and multiple points of intercultural contact the program offered, relationships with the faculty leader, peers, and host community members, and the compassionate leadership of the faculty leader as critical factors in their intercultural growth. I found that emotions, cognitive dissonance, and critical reflection play key roles in the intercultural learning process.
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    A Model to Convert Airport Geographic and Geometric Information into a Node-Link Network
    Zhang, Yang (Virginia Tech, 2015-01-17)
    An airport node-link network model is an important input for most airport simulation models. Developing, maintaining and updating detailed airport surface node-link models require significant work. A model to convert airport geographic and geometric information into a node-link network is thus needed. In this thesis, an efficient model to automate the procedure of converting airport geographic and geometric information into a node-link network is proposed. The geographic and geometric information are obtained from the Aeronautical Information Exchange Model (AIXM). The node-link network is generated by converting the geographic and geometric information contained into the AIXM files using coincident geometry management and polygon representation development. Finally, using the airport node-link network generation model, a standalone computer application, called Taxiway Toolkit, is developed to improve the Airfield Delay Simulation Model (ADSIM+).
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    Multi-Platform Next-Generation Sequencing of the Domestic Turkey (Meleagris gallopavo): Genome Assembly and Analysis
    Dalloul, Rami A.; Long, Julie A.; Zimin, Aleksey V.; Aslam, Luqman; Beal, Kathryn; Blomberg, Le Ann; Bouffard, Pascal; Burt, David W.; Crasta, Oswald; Crooijmans, Richard P. M. A.; Cooper, Kristal; Coulombe, Roger A.; De, Supriyo; Delany, Mary E.; Dodgson, Jerry B.; Dong, Jennifer J.; Evans, Clive; Frederickson, Karin M.; Flicek, Paul; Florea, Liliana; Folkerts, Otto; Groenen, Martien A. M.; Harkins, Tim T.; Herrero, Javier; Hoffmann, Steve; Megens, Hendrik-Jan; Jiang, Andrew; de Jong, Pieter; Kaiser, Pete; Kim, Heebal; Kim, Kyu-Won; Kim, Sungwon; Langenberger, David; Lee, Mi-Kyung; Lee, Taeheon; Mane, Shrinivasrao P.; Marcais, Guillaume; Marz, Manja; McElroy, Audrey P.; Modise, Thero; Nefedov, Mikhail; Notredame, Cédric; Paton, Ian R.; Payne, William S.; Pertea, Geo; Prickett, Dennis; Puiu, Daniela; Qioa, Dan; Raineri, Emanuele; Ruffier, Magali; Salzberg, Steven L.; Schatz, Michael C.; Scheuring, Chantel; Schmidt, Carl J.; Schroeder, Steven; Searle, Stephen M. J.; Smith, Edward J.; Smith, Jacqueline; Sonstegard, Tad S.; Stadler, Peter F.; Tafer, Hakim; Tu, Zhijian Jake; Van Tassell, Curtis P.; Vilella, Albert J.; Williams, Kelly P.; Yorke, James A.; Zhang, Liqing; Zhang, Hong-Bin; Zhang, Xiaojun; Zhang, Yang; Reed, Kent M. (PLOS, 2010-09-01)
    A synergistic combination of two next-generation sequencing platforms with a detailed comparative BAC physical contig map provided a cost-effective assembly of the genome sequence of the domestic turkey (Meleagris gallopavo). Heterozygosity of the sequenced source genome allowed discovery of more than 600,000 high quality single nucleotide variants. Despite this heterozygosity, the current genome assembly (,1.1 Gb) includes 917 Mb of sequence assigned to specific turkey chromosomes. Annotation identified nearly 16,000 genes, with 15,093 recognized as protein coding and 611 as non-coding RNA genes. Comparative analysis of the turkey, chicken, and zebra finch genomes, and comparing avian to mammalian species, supports the characteristic stability of avian genomes and identifies genes unique to the avian lineage. Clear differences are seen in number and variety of genes of the avian immune system where expansions and novel genes are less frequent than examples of gene loss. The turkey genome sequence provides resources to further understand the evolution of vertebrate genomes and genetic variation underlying economically important quantitative traits in poultry. This integrated approach may be a model for providing both gene and chromosome level assemblies of other species with agricultural, ecological, and evolutionary interest.
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    Networks in the Disaster Response and Global Health Domain: A case study of The Partnership for Quality Medical Donation's response to the 2010 Haitian Earthquake
    Arroyave, Veronica Margoth (Virginia Tech, 2013-05-08)
    The 2010 Haitian earthquake underscored the fact that disaster response is increasingly complex, multi-sectoral and multi-faceted in character. Nonetheless, disaster relief operations both globally and nationally tend to operate within a highly fragmented context in which potentially overwhelming human and infrastructure needs must be served by limited material and financial aid delivered by disparate humanitarian actors specializing in varying functional domains.  Such a chaotic environment demands highly effective communication, collaboration and coordination among a variety of humanitarian actors if relief efforts are to be successful. Even though the coordination mechanisms of multi-organizational actors during disaster response have been studied in a variety of contexts, much less attention has been paid to how international non-governmental (INGOs) and private sector actors may be able to operate collaboratively in disaster settings. This dissertation provides a case analysis of the efforts of one set of cross-sectoral humanitarian actors that worked through a network in response to the 2010 Haitian earthquake. This mixed methods case study incorporates interview, personal observation, and survey data from INGO field staff, headquarters personnel, and corporate donor representatives, all of whom were members of the cross-sectoral Partnership for Quality Medical Donation (PQMD) that responded to the 2010 Haitian earthquake.  The inquiry explores what the coordination-related challenges to disaster response are for network members and then examines whether and in what ways a cross-sector network, PQMD in this instance, can effectively mitigate or overcome those obstacles.  This study contributes to the body of disaster coordination and cross-sector network scholarship in two ways. First, the analysis reviews prevailing trends within the cross-sector network and disaster coordination-related literature concerning the requisites and challenges of coordination in humanitarian relief emergencies.  Second, this study augments existing understanding of the extremely complex processes involved in coordinating INGO-business disaster response as part of efforts to mobilize multi-sectoral humanitarian action. This research suggests that efforts to develop cross-sector networks prior to disaster events can build communication, collaboration and coordination pathways that later enhance coordinated INGO-business disaster response to crises.  It argues that current theoretical horizons in both network and disaster coordination studies need to be broadened. Specifically, this inquiry highlights the importance of incorporating cross-sector networks (i.e., INGO and corporate actors) into all planning efforts aimed at enhancing collaboration and coordination practices in disaster relief.
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    The Operationalization of Capacity Development: the Case of Urban Infrastructure Projects in India
    An, Yehyun (Virginia Tech, 2015-03-30)
    Since the 1950s, Capacity Development (CD) has been an important component of international development agendas. It established the widespread consensus that the capacity of individuals and organizations is critical to maintaining and enhancing the effectiveness of development projects and programs. A problem, however, is that the concept has been applied without due consideration to how it should be adapted to the local context, making it more of a symbolic gesture. The application of CD to urban infrastructure projects in India is one such example. Recognizing the shortage of urban infrastructure as one of the major impediments in India's economic growth and rapid urbanization, the Government of India (GOI) launched the Jawaharlal Nehru National Urban Renewal Mission (JNNURM) in December 2005 to provide substantial central financial assistance to cities for urban development over a period of seven years. The GOI expected the JNNURM to reform institutions and strengthen human resource capability related to many areas of project delivery. During its implementation, however, the JNNURM has been confronted by problems related to a lack of capacity. This research reviews the capacity challenges related to the JNNURM program and considers the broader implications for urban infrastructure development in other developing countries. This research begins with the question "How can CD be operationalized?" From this starting point, the research seeks to reveal the operational values of CD. Following a detailed literature review on CD, capacity factors that are applicable to the urban sector in India are identified and a CD framework is developed. Two research methods--case studies and fuzzy-set Qualitative Comparative Analysis (fsQCA)--are adopted to answer the primary research questions. By leveraging the strength of these two methods, this research advances our understanding of the relationship between capacity and development goals such as improving project performance. In the case studies, this research investigates the gaps between CD theory and practice through the lens of practitioner perceptions of CD. In addition, unlike traditional thinking on the linear relationship between capacity and project outcomes, the case studies reveal two-way causal relationships between capacity and project outcomes that form a spiral structure between the project delivery process and capacity factors. Better capacity can enhance project performance and lead to better outcomes, and project performance and outcomes also influence and reinforce capacity in the reverse direction. Moreover, through the fsQCA, this research identified causal relationships between capacity factors and outcomes and demonstrated that the capacity factors generate different outcomes through their interactions with other capacity factors. This finding contributes to our understanding of how capacity is interconnected with development goals. In summary, this research contributes to both CD theory and CD practice based on a comprehensive approach that not only considers CD at multiple levels (environmental, organizational/network, and individual/project), but also covers different CD subjects such as context, actors, dimensions, processes, and impacts. Through this comprehensive approach, a range of important findings are developed that can help researchers and practitioners operationalize the complex concept of CD.
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    Policy Diffusion in U.S. Hazard Mitigation Planning: An Intergovernmental Perspective
    Xie, Ruixiang (Virginia Tech, 2024-05-24)
    This dissertation contributes to the disaster resilience policy literature by examining the diffusion of hazard mitigation policy in the U.S. Using the three-paper model, it investigates the adoption of local hazard mitigation plans (LHMPs) from an intergovernmental perspective. The first paper focuses on horizontal diffusion in hazard mitigation planning among local communities. Special attention is paid to the potential factors affecting the adoption of FEMA-approved LHMPs, Hazard Mitigation Grant Program (HMGP) projects and Pre-Disaster Program (PDM) projects at the county level. The Event History Analysis (EHA) Logit Model and Spatial Autocorrelation Models test the hypotheses corresponding to external factors such as the neighboring effects and internal factors, including disaster risks, neighborhood disadvantage and affluence, government capacity, local disaster resilience advocacy groups, and political support. The empirical results confirmed the significant influence of neighboring effects, indicating that counties are more likely to implement the same mitigation strategies if neighboring counties have done so. The results also revealed that disaster experience, government capacity, and strong democratic support significantly impact the likelihood of adopting LHMP and HMGP. Additionally, the results suggested that disadvantaged communities were more likely to adopt mitigation policies, while affluent communities were less likely to adopt such policies. The second paper evaluates the effectiveness of the FEMA's Program Administration by State Pilot (PAS). By integrating the Propensity Score Matching (PSM) technique with the Difference-in-Differences (DID) analysis, the empirical evidence demonstrated a significant reduction in the approval times for both LHMP and HMGP in pilot states compared to non-pilot states, with an average reduction nearing 30%. This suggests that the PAS program has effectively streamlined administrative processes, thereby enhancing efficiency in disaster management within pilot states. The analysis also indicated that the impact of PAS on the actual funding received through HMGP was insignificant, suggesting that while administrative processes were expedited, the allocation of financial resources remained unaffected. The third paper attempts to understand how local governments respond to top-down policy pressures in vertical diffusion by analyzing the text similarities of hazard mitigation strategies between state hazard mitigation plans and county LHMPs in Ohio using the word embedding technologies. The study employs the Word2Vec algorithm to assess the policy similarity between the hazard mitigation goals outlined in LHMPs and SHMPs. Building on this initial analysis, this research further uses the Beta Regression model to examine the textual similarities within LHMPs in Ohio, focusing on how the type of author - government versus private consultants, and the nature of the goals, whether action-based or hazard-based, affect these alignments. The regression analysis shows that LHMPs authored by government entities tend to exhibit higher textual similarity, reflecting the influence of standardized approaches driven by state and federal guidelines. This suggests a compliance-driven alignment in government-written plans. Conversely, LHMPs authored by private consultants display greater variability, suggesting that these plans are customized to the specific needs and risk assessments of local communities. Additionally, the regression results indicate that action-based and mixed-goal LHMPs are associated with higher textual similarity across counties. To carry out the empirical analysis mentioned above, this dissertation builds a panel dataset for all counties from 2000 to 2020, which contains data on LHMPs, HMA projects, disaster risks, socioeconomic characteristics, regional economic and political indicators, etc.