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ItemEvaluation of Large-Format Metallic Additive Manufacturing (AM) for Steel Bridge Applications: Final Report of Tensile, Impact, and Fatigue Testing Results(Georgia Institute of Technology, 2023-10-11) Sherman, Ryan J. ; Kessler, Hannah D. ; Frank, Karl H. ; Medlock, RonnieWire arc additive manufacturing (WAAM) is an additive manufacturing process capable of printing using metallic feedstocks, such as traditional welding wire consumables. Advances in WAAM allow large-scale components, measured on the scale of feet, to be fabricated. A lack of fundamental knowledge of the material and fatigue behaviors of WAAM currently prevents its widespread adoption into structural engineering. To address this need, the first objective of this work was to create material property datasets for WAAM ER70S-6 and ER80S-Ni1through tension and notched bar impact (Charpy V-notch) tests. The second objective was to determine the influence of the as-fabricated surface finish on the fatigue behavior of WAAM ER70S-6 steel components through uniaxial fatigue tests on specimens. No significant anisotropy (difference in properties with respect to the build direction and deposition direction of the part) was noted in the yield and tensile strengths of the WAAM ER70S-6and ER80S-Ni1 material. Low levels of anisotropy were observed in the elongation at fracture of the tensile specimens and the impact energies of the CVN specimens. The impact energies of all WAAM specimens tested at or above the AASHTO service temperatures exceeded the fracture critical Grade 50 steel requirement. Fatigue specimens with the machined surface finish exceeded the upper bound life of AASHTO fatigue detail category A.A 95 percent confidence limit regression with the slope set to 3.0 for all the as-built surface specimens exceeded AASHTO fatigue detail category D.
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ItemA Transfer Learning-Based Framework for Enriching National Household Travel Survey Data with Attitudinal Variables(Georgia Institute of Technology, 2022-06) Malokin, Aliaksandr ; Mokhtarian, Patricia L. ; Circella, GiovanniOften in practice, the problem of unavailability of specific desired knowledge within one (“target”) dataset arises. However, if this knowledge can be extracted from a different (“source”) dataset and transferred between the datasets, this could increase the value of the target dataset at relatively minimal cost. The goal of this paper is to evaluate approaches to informing one dataset with knowledge from another and to evaluate the performance of the knowledge transferred into the target dataset. We use the 2009 National Household Travel Survey as the target dataset. The missing knowledge is transportation-related attitudes, whose inclusion could greatly improve travel behavior models. Our source dataset is obtained from the 2011–12 Multitasking Survey of Northern California Commuters. To achieve the goal, the set of common variables was first augmented with a large number of built-environment attributes. Then, after applying machine-learning methods, pro-transit, pro-active transportation, and pro-density attitudinal factor scores were predicted with the greatest precision; correlations of the predicted and observed scores were 0.564, 0.538, and 0.571, respectively. The performance of the transferred attitudes was measured by estimating linear regression models of vehicle ownership. The results showed that in the source dataset the observed attitudes account for an 8.0% model lift (improvement in goodness of fit), while in the target dataset the predicted attitudes account for a 1.2–5.4% model lift. Although these initial results are modest, we believe they show substantial promise, and the process has identified a number of opportunities for improvement and further research.
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ItemAnalysis of the Georgia Add-on to the 2016-2017 National Household Travel Survey(Georgia Institute of Technology, 2021-08) Kash, Gwen ; Mokhtarian, Patricia L. ; Circella, GiovanniThrough an extensive analysis of the Georgia subsample of the 2016–2017 National Household Travel Survey, this report provides an in-depth snapshot of the travel behavior of Georgians of all ages. It documents differences in travel needs and behavior by region and between demographic groups, focuses on measurement challenges and improved techniques, and identifies areas where future data collection is needed. In addition to an overview of key travel trends in the state, the report includes chapters on work travel; work flexibility (teleworking and flexible scheduling); new technologies and services, including alternative-fuel vehicles, shared mobility, and online shopping; social inclusion and equity; nonmotorized and access/egress travel; and travel for its own sake.
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ItemMonthly Maps of SMAP L2 Version 4 Soil Moisture Retrievals over Contiguous United States in 2016: Data Sample Size Under Various Quality Flags(Georgia Institute of Technology, 2017-05-07) Lin, Liao-Fan ; Bras, Rafael L.This document presents the data sample size of the SMAP L2 Version 4 soil moisture retrievals for each month during 2016 and the percentages of the soil moisture data within some quality control limits defined by NASA. The soil moisture retrievals of each 36-km grid cell are associated by NASA to a surface condition and retrieval quality flag. Each half orbit was obtained from https://nsidc.org/data/SPL2SMP/versions/4. There are 11 surface conditions defined in the SMAP data: static water, radar-derived water, coastal proximity, urban area, precipitation, snow, permanent ice, frozen ground from SMAP radiometer-derived freeze/thaw state, frozen ground from GMAO TSURF model, mountainous terrain, and dense vegetation. For each surface condition, a lower threshold T1 and a higher threshold T2 are defined. Only data with all surface conditions under the T1 threshold are flagged as high quality. In this document, we use three variables (i.e.,soil_moisture, surface_flag, and retrieval_qual_flag) from each data file to illustrate the distribution and quality of the data.
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ItemWorkshop Report: "Risks and Policies of Hydraulic Fracturing: Assessment and Deliberation", Georgia Tech, November 13-14, 2014(Georgia Institute of Technology, 2014-11) Arson, Chloé ; Kirkman, Robert ; Stewart, Lauren K.Report of the workshop: Risks and Policies of Hydraulic Fracturing: Assessment and Deliberation, held at Georgia Tech, November 2014. Report includes the following: 1. Workshop program 2. Communication: \The Fracking Debate in Europe", Dr. Terry Engelder, Professor, Department of Geosciences, Pennsylvania State University 3. Presentation:\State Review of Oil & Natural Gas Environmental Regulations, Inc." Mr. Ryan Steadley, executive director, Stronger Inc. 4. Presentation:\Conveying the Science of Risk - Evolving Perceptions Within Non-Technical Audiences", Mr. Thomas Murphy, Director of Penn State Marcellus Center for Outreach and Research 5. Presentation: \Hydraulic Fracturing: An engineering perspective on modeling issues", Mr. Hao Xu (Ph.D. student), Ms. Amanda Francis (undergraduate research assistant), Dr. Chloé Arson (Assistant Professor), School of Civil & Environmental Engineering, Georgia Institute of Technology 6. Presentation: \Acceptable Risk and the Policy Context of Hydraulic Fracturing", Dr. Robert Kirkman, Associate Professor, School of Public Policy, Georgia Institute of Technology 7. Abstract presented at the 2015 Annual International Conference of the Association of Practical and Professional Ethics: \An Integrative Approach to the Ethics of Hydraulic Fracturing: A Report on Work in Progress", Dr. Robert Kirkman, Ms. Rebecca Harris, Ms. Amanda Francis, Mr. Hao Xu, Dr. Chloé Arson, Dr. Lauren Stewart, Georgia Institute of Technology
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ItemBook of Abstracts Report from: International Workshop on Education of Future Geotechnical Engineers in Response to Emerging Multi-scale Soil-Environment Problems(Georgia Institute of Technology, 2014-09) Arson, Chloé ; Buscarnera, GiuseppeBook of abstracts compiled by over 40 participants, as part of a workshop organized by Principal Investigators Chloé Arson and Giuseppe Buscarnera, under NSF Grant CMMI-1443990. The workshop addressed the new skill set needed by Geotechnical Engineers to solve the multi-scale, multi-physics problems faced by modern technology. New research areas such as solid/fluid transition from the grain to the landslide; geological waste storage from micro-cracks to fractured reservoirs; bio-engineered geomerials from natural bacteria to designed structures; energy piles from soil properties to geotechnical performance; geotechnical earthquake engineering: from ground motion to structural safety all require a broader range of knowledge than previously provided in the typical Geotechnical Engineering course of study. This International Workshop aims to identify key challenges for the education of new generations of geotechnical engineers, focusing on undergraduate education. This book of abstracts was one of the outcomes of this workshop, for articles to be submitted for a special issue in the journal ASCE Journal of Professional Issues in Engineering Education and Practice.
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ItemRegional air quality management aspects of global change: impact of climate-responsive controls and forest management practices on regional air quality and associated uncertainties(Georgia Institute of Technology, 2013-12) Russell, Armistead G. ; Nenes, Athanasios ; Wang, YuhangThe overarching objective of this study is to provide information as to which global change-related control choices and forest management and utilization practices are most effective for both mitigating climate change and improving regional air quality. Four specific objectives are identified to address critical scientific issues linking global change with assessment of regional air quality and forest management practices: • Assess and compare how climate-responsive control choices will affect regional air quality • Assess how forest management and utilization practices will impact future regional climate and air quality • Quantify the sensitivities and dominant uncertainties associated with predicted impacts • Provide focused information for policy makers on the impact of climate change/global change on strategies to meet air quality policy goals in the future, including providing results for direct use in decision support analyses.
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ItemAtlanta I-85 HOV-to-HOT Conversion: Analysis of Vehicle and Person Throughput(Georgia Institute of Technology, 2013-10) Guensler, Randall L. ; Elango, Vetri ; Guin, Angshuman ; Hunter, Michael D. ; Laval, Jorge A. ; Araque, Santiago ; Colberg, Kate ; Castrillon, Felipe ; D’Ambrosio, Kate ; Duarte, David ; Khoeini, Sara ; Peesapati, Lakshmi ; Sheikh, Adnan ; Smith, Katie ; Toth, Christopher ; Zinner, StephanieThis report summarizes the vehicle and person throughput analysis for the High Occupancy Vehicle to High Occupancy Toll Lane conversion in Atlanta, GA, undertaken by the Georgia Institute of Technology research team. The team tracked changes in observed vehicle throughput on the corridor and collected average vehicle occupancy (persons/vehicle) data to assess changes in person throughput. Traffic volumes were collected by VDS systems on the Georgia NaviGAtor system and the team implemented a large scale quarterly data collection effort for vehicle occupancy across all travel lanes.
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ItemQuantification of the energy potential from tidal streams for Rose Dhu Island, Georgia(Georgia Institute of Technology, 2012-04-07) Fedele, Francesco G. ; Haas, Kevin A. ; Stoesser, Thorsten
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ItemDevelopment of quantitative structure-activity relationship for prediction of biological effects of nanoparticles associated with semiconductor industries(Georgia Institute of Technology, 2012-03) Chen, Yongsheng ; Li, Kungang ; Zhang, Wen ; Li, YangOur work aims at development of fundamental understanding of cytotoxicity of semiconductor NPs to human health and provides a comprehensive database and clear definition of ESH-problematic manufactured nanomaterials. Based on the quantitative structure-activity relationship (QSAR) model we plan to establish, problematic nanomateirals from industrial manufacturers could be predicted, identified, and effectively modified to produce environmental benign semiconductor nanomaterials.