Civil & Environmental Engineering Research Works
Permanent URI for this collectionhttp://hdl.handle.net/1903/1657
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Item Biobjective optimization for railway alignment fine-grained designs with parallel existing railways(Wiley, 2024-01-09) Gao, Yan; Zhang, Tianlong; Zhu, Caiyiyi; Yang, Shusheng; Schonfeld, Paul; Zou, Kai; Zhang, Jialing; Zhu, Ying; Wang, Ping; He, QingUrban high-speed railway construction is complex due to limited land resources, high population density, and potential construction risks, especially when new tracks are parallelly aligned to operational railways. Addressing a gap in current literature on fine optimization of manual alignment in such scenarios, this paper introduces a biobjective approximate fine-grained optimization model for railway alignments (BA-FORA). Utilizing an approximate dynamic programming (ADP) method, BA-FORA effectively searches the feasible region to approach a global optimum, overcoming the dimensionality challenges inherent in standard dynamic programming (DP). This paper presents a biobjective optimization framework that takes into account both construction cost and construction risk adjacent to existing operating railways (CRAEOR), offering a method for the fine-grained design of new railways adjacent to existing railways. Finally, the proposed BA-FORA framework is applied to practical cases, demonstrating its superior optimization performance. The findings indicate that the BA-FORA model can autonomously investigate and enhance railway alignment. It generates cost-effective and low-risk solutions exceeding manual efforts, ensuring alignment constraint compliance.Item Assessing the performance of polyphosphate accumulating organisms in a full-scale side-stream enhanced biological phosphorous removal(Wiley, 2024-01-11) Aghilinasrollahabadi, Khashayar; Ghandehari, Shahrzad Saffari; Kjellerup, Birthe Veno; Nguyen, Caroline; Saavedra, Yerman; Li, GuangbinPhosphorous (P) removal in wastewater treatment is essential to prevent eutrophication in water bodies. Side-stream enhanced biological phosphorous removal (S2EBPR) is utilized to improve biological P removal by recirculating internal streams within a side-stream reactor to generate biodegradable carbon (C) for polyphosphate accumulating organisms (PAOs). In this study, a full-scale S2EBPR system in a water resource recovery facility (WRRF) was evaluated for 5 months. Batch experiments revealed a strong positive correlation (r = 0.91) between temperature and C consumption rate (3.56–8.18 mg-COD/g-VSS/h) in the system, with temperature ranging from 14°C to 18°C. The anaerobic P-release to COD-uptake ratio decreased from 0.93 to 0.25 mg-P/mg-COD as the temperature increased, suggesting competition between PAOs and other C-consumers, such as heterotrophic microorganisms, to uptake bioavailable C. Microbial community analysis did not show a strong relationship between abundance and activity of PAO in the tested WRRF. An assessment of the economic feasibility was performed to compare the costs and benefits of a full scale WRRF with and without implementation of the S2EBPR technology. The results showed the higher capital costs required for S2EBPR were estimated to be compensated after 5 and 11 years of operation, respectively, compared to chemical precipitation and conventional EBPR. The results from this study can assist in the decision-making process for upgrading a conventional EBPR or chemical P removal process to S2EBPR.Item Agricultural practices influence foliar endophytic communities in coffee plants of different varieties(Wiley, 2023-02-16) Castillo-Gonzalez, Humberto; Bloomberg, Joshua; Alvarado-Picado, Eduardo; Yarwood, Stephanie; Chaverri, PriscilaFungal endophytes are pivotal components of a plant's microbiome, profoundly impacting its health and fitness. Yet, myriad questions remain concerning the intricate interactions between these microorganisms and their hosts, particularly in the context of agriculturally important plants such as Coffea arabica. To bridge this knowledge gap and provide a comprehensive framework, this study investigated how farming practices shape the taxonomic and functional diversity of phylloplane endophytes in coffee. Coffee plant leaves from two distinct producing regions in Costa Rica were sampled, ensuring the representation of various coffee varieties (Obatá, Catuaí, and Caturra), agricultural management methods (organic vs. conventional), sun exposure regimes (full sunlight/monoculture vs. natural shade/agroforestry), and leaf developmental stages (newly emerged asymptomatic vs. mature leaves). Fungal communities were characterized by employing both culture-dependent and independent techniques (internal transcribed spacer 2 nuclear ribosomal DNA metabarcoding). The results showed a greater diversity of endophytes in mature leaves and conventionally managed plants, with coffee variety exerting an unclear influence. The effect of sun exposure was surprisingly negligible. However, data emphasize the benefits of agroforestry and organic farming, which are linked to reduced putative pathogens and heightened levels of potentially mutualistic fungi, fostering functionally diverse communities. Despite the role that plant microbiomes might play in agricultural production, the knowledge to shape endophytic communities through breeding or management is lacking. The results from this study provide a framework to understand how both plant and agricultural practices influence endophyte diversity within coffee crops. These insights hold promise for guiding future efforts to manipulate coffee microbial communities effectively.Item Rent affordability after hurricanes: Longitudinal evidence from US coastal states(Wiley, 2023-10-04) Best, Kelsea; He, Qian; Reilly, Allison; Tran, Nhi; Niemeier, DebClimate change is expected to increase the frequency and intensity of natural hazards such as hurricanes. With a severe shortage of affordable housing in the United States, renters may be uniquely vulnerable to disaster-related housing disruptions due to increased hazard exposure, physical vulnerability of structures, and socioeconomic disadvantage. In this work, we construct a panel dataset consisting of housing, socioeconomic, and hurricane disaster data from counties in 19 states across the East and Gulf Coasts of the United States from 2009 to 2018 to investigate how the frequency and intensity of a hurricane correspond to changes in median rent and housing affordability (the interaction between rent prices and income) over time. Using a two-stage least square random-effects regression model, we find that more intense prior-year hurricanes correspond to increases in median rents via declines in housing availability. The relationship between hurricanes and rent affordability is more complex, though the occurrence of a hurricane in a given year or the previous year reduces affordable rental housing, especially for counties with higher percentages of renters and people of color. Our results highlight the multiple challenges that renters are likely to face following a hurricane, and we emphasize that disaster recovery in short- and medium-term should focus on providing safe, stable, and affordable rental housing assistance.Item Two algorithms for reconstructing vertical alignments exploring the neural dynamics model of Adeli and Park(Wiley, 2023-09-26) Song, Zhanfeng; Chen, Jinye; Schonfeld, Paul M.; Li, JunVertical alignment reconstruction obtains alignment parameters by fitting geometric components to a set of measured points representing the profile of an existing road or railroad, which is essential in alignment consistency analysis and maintenance to ensure safety and comfort. The neural dynamics model of Adeli and Park is explored and improved for reconstructing vertical alignments with constraints. The structure of the dynamics model is modified to include three layers: parameter layer, intermediate layer, and energy layer. The number of nodes in the parameter or intermediate layers corresponds to the number of independent parameters defining a vertical alignment. The number of nodes in the energy layer is the sum of the number of deviations and the number of constraints in the alignment reconstruction problem. The coefficients connecting nodes between the parameter layer and the intermediate layer determine the integral operations, which define the Levenberg–Marquardt algorithm of the dynamics model (LMADM) and the steepest descent algorithm of the dynamics model (SDADM). Both the LMADM and SDADM methods satisfy the Lyapunov stability theorem, but the LMADM method outperforms the SDADM method in its objective function value and computation time. Experiment results demonstrate that there are multiple local optima for a vertical alignment reconstruction, and the solutions obtained by the LMADM method are the best obtained so far, compared with those reported in the literature, with 57.1% and 23.4% decreases of the mean squared error for the highway and the railroad examples, respectively.Item Ensuring the continued success of a mulch biowall at a trichloroethylene-contaminated superfund site: Lessons learned(Wiley, 2023-08-03) Ghandehari, Shahrzad Saffari; Cheng, Shih-Huai; Hapeman, Cathleen J.; Torrents, Alba; Kjellerup, Birthe VenoTrichloroethylene (TCE) is a toxic organic compound, which can adversely affect human health. The chemical is one of the most frequently found contaminants in groundwater in the United States and around the world. A landfill in Maryland contaminated with high levels of TCE decades ago was added to the U.S. Environmental Protection Agency's National Priority List (NPL) in 1994. A biowall was installed on the site in 2013 to promote the bioremediation of TCE and subsequently of its degradation products. Six-year monitoring data indicated a steady removal of >99% groundwater TCE at the wall since installation. However, a concurrent buildup of intermediate byproducts was observed downgradient of the wall. An examination of the entire system was necessary to find the reason behind the inefficiency of the biowall. In this study, the background of the site, remediation plan, and installation were assessed. Monitoring data, including the concentration of TCE and its degradation byproducts, and geochemical and physical characteristics were evaluated to understand the conditions and challenges facing decision-makers of this project and possible options to improve biowall efficacy.Item Mountain railway alignment optimization based on landform recognition and presetting of dominating structures(Wiley, 2023-07-23) Wan, Xinjie; Pu, Hao; Schonfeld, Paul; Song, Taoran; Li, Wei; Peng, Lihui; Hu, Jianping; Zhang, MingMountain railway alignment optimization has always been a challenge for designers and researchers in this field. It is extremely difficult for existing methods that optimize alignments before major structures to generate a better alignment than the best one provided by human designers when the terrain is drastically undulating between the start and endpoints. To fill this gap, a “structures before alignments” design process is proposed in this paper. Primarily, a landform recognition method is devised for recognizing dominating landforms. Then, a bi-level alignment optimization model is proposed, with the upper level dedicated to characterizing dominating structures and the lower level focusing on optimizing the entire alignments. To solve this bi-level model, a three-stage optimization method is designed. At the first stage, a scanning process and screening operators are devised for generating all the possible locations of dominating structures. At the second stage, a hierarchical multi-criteria decision-making procedure is applied for selecting the optimized dominating structure layouts. At the third stage, alignments are optimized based on the determined structure layouts using a bi-objective optimization method, which minimizes construction cost and geo-hazard risk simultaneously. The proposed model and solution method are applied to two real-world cases whose results verify their capabilities in producing alignment alternatives with better combinations of construction cost and geo-hazard risk than manually designed alternatives.Item Demographics and risk of isolation due to sea level rise in the United States(Springer Nature, 2023-11-30) Best, Kelsea; He, Qian; Reilly, Allison C.; Niemeier, Deb A.; Anderson, Mitchell; Logan, TomWithin coastal communities, sea level rise (SLR) will result in widespread intermittent flooding and long-term inundation. Inundation effects will be evident, but isolation that arises from the loss of accessibility to critical services due to inundation of transportation networks may be less obvious. We examine who is most at risk of isolation due to SLR, which can inform community adaptation plans and help ensure that existing social vulnerabilities are not exacerbated. Combining socio-demographic data with an isolation metric, we identify social and economic disparities in risk of isolation under different SLR scenarios (1-10 ft) for the coastal U.S. We show that Black and Hispanic populations face a disproportionate risk of isolation at intermediate levels of SLR (4 ft and greater). Further, census tracts with higher rates of renters and older adults consistently face higher risk of isolation. These insights point to significant inequity in the burdens associated with SLR.Item Elimination of Bloodstream Infections Associated with Candida albicans Biofilm in Intravascular Catheters(MDPI, 2015-06-29) Akbari, Freshta; Kjellerup, Birthe VenoIntravascular catheters are among the most commonly inserted medical devices and they are known to cause a large number of catheter related bloodstream infections (BSIs). Biofilms are associated with many chronic infections due to the aggregation of microorganisms. One of these organisms is the fungus Candida albicans. It has shown to be one of the leading causes of catheter-related BSIs. The presence of biofilm on intravascular catheters provide increased tolerance against antimicrobial treatments, thus alternative treatment strategies are sought. Traditionally, many strategies, such as application of combined antimicrobials, addition of antifungals, and removal of catheters, have been practiced, but they were not successful in eradicating BSIs. Since these fungal infections can result in significant morbidity, mortality, and increased healthcare cost, other promising preventive strategies, including antimicrobial lock therapy, chelating agents, alcohol, and biofilm disruptors, have been applied. In this review, current success and failure of these new approaches, and a comparison with the previous strategies are discussed in order to understand which preventative treatment is the most effective in controlling the catheter-related BSIs.Item Model-Based Design and Formal Verification Processes for Automated Waterway System Operations(MDPI, 2016-06-07) Petnga, Leonard; Austin, MarkWaterway and canal systems are particularly cost effective in the transport of bulk and containerized goods to support global trade. Yet, despite these benefits, they are among the most under-appreciated forms of transportation engineering systems. Looking ahead, the long-term view is not rosy. Failures, delays, incidents and accidents in aging waterway systems are doing little to attract the technical and economic assistance required for modernization and sustainability. In a step toward overcoming these challenges, this paper argues that programs for waterway and canal modernization and sustainability can benefit significantly from system thinking, supported by systems engineering techniques. We propose a multi-level multi-stage methodology for the model-based design, simulation and formal verification of automated waterway system operations. At the front-end of development, semi-formal modeling techniques are employed for the representation of project goals and scenarios, requirements and high-level models of behavior and structure. To assure the accuracy of engineering predictions and the correctness of operations, formal modeling techniques are used for the performance assessment and the formal verification of the correctness of functionality. The essential features of this methodology are highlighted in a case study examination of ship and lock-system behaviors in a two-stage lock system.