1,721,011 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Validating the Quality of Crowdsourced Data for Flood Modeling of Hurricane Harvey in Houston, Texas
No full textFlood is one of the most widespread natural hazards in the world. Hurricane Harvey, a 1000-year flood event, hit Texas in 2017 and resulted in significant property damage, bodily injury, and casualty. As one of the most impacted areas, Houston is chosen to be the study area of this study. For future flood risk prediction and mitigation, it is important to find out the flood dynamics of Hurricane Harvey and generate flood inundation maps.
In these years, Volunteered Geographic Information (VGI) data such as social media and crowdsourced data arise as an alternative and supplementary data source to enhance the exercise of flood inundation mapping. However, compared to authoritative data acquired by government agencies (i.e. stream gage data, remote sensing), the quality of crowdsourced data often exists uncertainty due to lack of clear data standard and quality assurance/quality control (QA/QC) procedure. Therefore, the primary objective of this study was to examine the quality of crowdsourced data for flood mapping of Hurricane Harvey in the Houston area. As a free and innovative crowdsourced platform, the U-Flood project (map.u-flood.com), which reported and mapped flooded streets in the Houston metro area, is the target crowdsourced data to be examined in this study. The research questions of this study include (1) Are there any significant differences in the water depth among the H&H model (i.e. HEC-RAS), authorized reference (i.e. FEMA) and crowdsourced data (i.e. U-Flood data)? (2) Are there any significant differences in the inundated areas between the HEC-RAS modeled floodplain and U-Flood data observations? To answer these research questions, this study used HEC-RAS to simulate flood inundation maps in the Houston study area during Hurricane Harvey and validate the result maps by comparing with Harvey High Water Marks (HWM) points using Wilcoxon sign rank test, and comparing with FEMA modeled floodplain using paired-samples t-test. Next, the crowdsourced U-Flood dataset was validated by comparing with HEC-RAS modeled result and the authorized reference (i.e. FEMA modeled flood map for Hurricane Harvey and USGS stream gages) in terms of a) water depth (WD) using Friedman test and b) the percentage of U-Flood street’s count and length inside / outside of HEC-RAS modeled floodplain. In addition, the U-Flood dataset is compared with HEC-RAS and FEMA separately using the Wilcoxon Sign Rank test. The statistical results showed that there was a statistically significant difference among all comparison sets in terms of WD. In addition, the results showed that there was a statistically significant difference between the HEC-RAS modeled floodplain and U-Flood data in terms of U-Flood count and length inside/outside of HEC-RAS modeled floodplain. The results showed that a less consistent decreasing trend between U-Flood data and the modeled floodplain over time. Moreover, the U-Flood data distribution map with the WD difference level also visually displays spatial distribution.
Overall, this study provides a preliminary evaluation of data quality of VGI by comparing the WD among crowdsourced data, authoritative data, and HEC-RAS modeled output. Furthermore, the theoretical significance of this study as the first study in empirically comparing crowdsourced data with observed and modeled data in flood monitoring. Findings from this study also fill gaps in the literature of improving and assessing the uncertainty of crowdsourced data quality, and crowdsourcing data supplements in flood mapping research.Geography and Environmental Studie
Predicting International Travel Destinations from Geotagged Flickr Photos
No full textNo abstract prepared.Geography and Environmental Studie
The Impact of Various land-use zoning and government restrictions on Environmental Sustainability in San Marcos, Texas
No full textThe purpose of this thesis is to investigate the impact of various land-use zoning and restrictions through government regulations preserving green space to promote environmental sustainability in San Marcos, TX. Located in the I-35 corridor between Austin and San Antonio in Central Texas, this area has experienced tremendous population growth from 2010-2020 and is continuing to have exceptional growth. An Agent-Integrated Irregular Automate (AIIA) model is used combining the spatial benefits of irregular Cellular Automata (CA) while representing urban dynamics with Agent-Based Model (ABM) agents. This project modeled urban growth via AIIA to examine the impacts of government regulations of growth restrictions and multifamily housing on green space preservation and environmental sustainability. The reliability of the urban growth simulation is demonstrated by modelling historical data over 20 years (2000-2020) and comparing the results with the actual 2020 land-use map. In addition to an unrestricted scenario, three scenarios are simulated testing the impact of an urban growth boundary and various housing land-use zoning and regulations. Comparison analysis revealed that government regulations on residential housing preserved more green space than without them. However, the most regulated scenario with restrictions on both single-family and multifamily housing did not result in the largest amount of green space being preserved. A scenario with an urban growth boundary and no regulations on housing produced the best results when comparing the retention of green space. Potential explanations for these results include population demographics and model parameters affecting developer agents’ goal to maximize profits.Geography and Environmental Studie
Assessing the Effects of Hydrologic Enforcement Methods in a Central Texas Watershed
No full textNo abstract prepared.Geography and Environmental Studie
Does Better Accessibility to Exercise Facilities Mean People Use Them More?
No full textGIS provides an excellent means for visualizing and analyzing health spatial data, geographically integrating large amounts of information from different sources and serving as a common platform for health data, recreation facilities, as well as indoor/outdoor activities. At the same time, social media provides an effective and accurate way for us to learn about the lifestyles of representative individuals within a region. Twitter is one of the most popular social media in the United States. Some users reveal their position with posts, which can let us know what and when are they doing, as well as where are they. The combination of GIS and social media helps to identify the characteristics of users’ social media behavior that tend to be associated with their activities, both indoor and outdoor considered. In this research, keyword searching was used to filter tweets related to physical activities: parks, trails, and open spaces refer to outside activities, geocoded gyms and facilities refer to indoor activities. Service areas were defined for different levels of facilities, and then every tweet location was evaluated for its access to physical activity facilities. The same analysis was applied at the zip code level. Last, whether the accessibility affects activity was tested by statistical hypothesis testing method. As a result, the average accessibility of indoor activity-related tweets’ location is not significantly different from the average of unrelated tweets’ location. However, the average accessibility of outdoor activity-related tweets’ location was significantly lower than the average of unrelated tweets’ location. That's the reason why we cannot say there is any expected quantity relationship was figured out.Geography and Environmental Studie
Modeling Probable North Korean Escape Routes in the Manchuria Area
No full textVarious humanitarian issues, such as human rights violations and widespread famine, have led thousands trying to flee North Korea to embassies within their neighboring countries that will deport them to South Korea. During this escaping journey, North Korean refugees face a life and death situation. This study attempts to answer the following research questions: 1) Are there significant differences in weight assignments between the scenario-based or random simulations across six environmental factors? 2) What are the geographic similarities/differences of resulting probable escape routes between the scenario-based or random simulations? The objective of this study is to use a GIS-approach to understand the underlying factors affecting escape routing along the North Korean and China border. This research applies the least-cost distance based on weights derived from Weighted Linear Combination (WLC) that considers all factors in escape routing. In the WLC process, thirty random values will be determined in order to simulate the chaotic nature of escaping North Korea. The factors examined in this study include roads, surface water, NDVI (Normalized Difference Vegetation Index), anthropogenic lights, topography, and viewshed. Varying weight assignments will be adopted to reflect preference that the individual may adopt at the time. This research seeks to contribute a technical GIS approach to a sensitive topic that has rarely been covered previously and potentially affects many lives.Geography and Environmental Studie
Examining the Driving Factors of Urban Sprawl in San Antonio Metropolitan Area During 1990-2010
No full textNo abstract prepared.Geography and Environmental Studie
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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