University of Louisiana at Lafayette
  • Lafayette, Louisiana, United States
Recent publications
Tidal marshes and mangroves are increasingly valued for nature-based mitigation of coastal storm impacts, such as flooding and shoreline erosion hazards, which are growing due to global change. As this review highlights, however, hazard mitigation by tidal wetlands is limited to certain conditions, and not all hazards are equally reduced. Tidal wetlands are effective in attenuating short-period storm-induced waves, but long-period storm surges, which elevate sea levels up to several meters for up to more than a day, are attenuated less effectively, or in some cases not at all, depending on storm conditions, wetland properties, and larger-scale coastal landscape geometry. Wetlands often limit erosion, but storm damage to vegetation (especially mangrove trees) can be substantial, and recovery may take several years. Longer-term wetland persistence can be compromised when combined with other stressors, such as climate change and human disturbances. Due to these uncertainties, nature-based coastal defense projects need to adopt adaptive management strategies. Expected final online publication date for the Annual Review of Marine Science, Volume 15 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
A new predictive frequency management system is designed for multi-area microgrids (MGs). The uncertainties are online modeled by a deep learned type-2 (T2) fuzzy-logic system (FLS) and singular-value decomposition (SVD) approach. The predictive controller is designed based on the SVD-T2FLS model. The robustness against perturbations is ensured by the adaptive learning laws and adaptive compensators. The learning rules are extracted from stability and robustness investigation. The effect of demand response (DR), multiple load changes, high dynamic perturbations and variation of wind speed and solar energies are studied. The simulations on two case study systems and comparisons with other fuzzy logic controllers (FLCs), demonstrate that the suggested approach is well effective and results in good regulation accuracy.
The special temperature-pressure environment and narrow safety density window of the deepwater formation pose a great challenge to wellbore pressure control during drilling. The downhole variable-gradient drilling method is an effective idea to solve this challenge. However, previous studies mainly focused on the theoretical adaptability analysis of this method, while the experimental feasibility verification has not yet been reported. In this paper, based on the segmental control principle of wellbore fluid density, we set up an indoor physical experiment system to investigate the feasibility of variable-gradient drilling method based on downhole cyclone separator. Using this experimental system, we investigated the effect of drilling fluid physical parameters, hollow glass microsphere (HGMS) performance parameters and engineering parameters on the separator separation efficiency, wellbore pressure gradient and HGMS slip rate. The experimental results revealed that the separator could separate the HGMSs into the annulus from the fluid mixture in the drill pipe. The separation efficiency increased with the increase in the HGMS diameter, HGMS concentration and flow rate, while decreased with the increase in the HGMS density and fluid viscosity. The HGMS density and HGMS concentration were the key factors affecting the annulus pressure gradient value, and the separator separation efficiency was the main factor determining the difference of the annulus pressure gradient. The HGMS slip rate was highly sensitive to its diameter and fluid viscosity, and a combination of optimal HGMS diameter and fluid viscosity could avoid the drilling risk caused by the HGMS slippage. Therefore, the variable-gradient drilling method based on downhole separator is feasible, which is able to create two or more pressure gradients in the annulus. This study could provide guidance for the optimization of key parameters and the development of equipment related to the variable-gradient drilling.
Knowledge of wellbore multiphase flow characteristics is important for early gas invasion identification and treatment, especially in oil-based drilling fluid. The wellbore multiphase flow law in downhole dual-gradient drilling (DDGD) is more complex than that in conventional single-gradient drilling. There was no relevant literature report at present. In this paper, considering the synergistic feedback relationship of multiphase flow, interphase mass transfer, and wellbore temperature, a fully transient wellbore multiphase flow model was established based on oil-based drilling fluid in deepwater DDGD. The model also coupled the variable temperature–mass flows caused by the dynamic transfer of hollow glass balls and formation gas. The bubble interface mass transfer theory was adopted to describe the interphase mass transfer rate. The model was verified through the experimental measurement data. The calculated results indicated that the dynamic transfer of hollow glass balls varied the wellbore pressure gradient and flow rate in DDGD, resulting in a sudden decrease in gas fraction and gas solubility along the flow direction at the separator. Additionally, the transient interphase mass transfer and wellbore temperature had large impact on the wellbore multiphase flow behaviors. Moreover, the model based on bubble interface mass transfer theory could more accurately characterize the development of the wellbore multiphase flow. This research could provide a certain theoretical basis for the detection and treatment of gas invasion in deepwater DDGD.
In the process of geothermal well drilling, the high-temperature rock in the reservoirs is cooled by different cooling media, which leads to the change of mechanical properties, affecting the rock-breaking efficiency of the bit. Sandstone and granite were taken as the research objects and heated to 400 °C, 600 °C, and 800 °C, then were cooled by natural, water, and liquid nitrogen (LN2) cooling. Ultrasonic detector tests, the split Hopkinson pressure bar (SHPB) experiments, and scanning electron microscope (SEM) tests were conducted. The effects of heating temperature and cooling methods on the dynamic mechanical properties were quantified and analyzed. Thermal shock damage evolution and the damage mechanism of high-temperature rock under different cooling ways were discussed. The fractal method was applied to the analysis of fragment distribution, to obtain the corresponding relationship between fractal dimension and heat treatment temperature and cooling methods. The research results showed that thermal and cooling treatment has a significant effect on the mechanical properties of rock. With the increase of the treatment temperature, the dynamic peak stress decreased, and the peak strain increased. The temperature sensitivity of sandstone to temperature was higher than that of granite, while sandstone was more significantly affected than granite in terms of the sensitivity of the cooling method. Fractal dimension could be used to analyze the fragmentation of high-temperature rock cooled in different ways after impact. The experimental results were expected to provide an adequate theoretical basis for the development and utilization of geothermal resources.
Reliability-centered maintenance (RCM) has recently emerged as a powerful tool to reasonably cut the operation and maintenance cost of power destruction systems, whilst meeting both power quality and reliability requirements. This study introduces a new RMC approach that allocates maintenance budgets based on component criticality and importance. A new diagnostic importance factor, implemented based on the criticality and importance of each component, is introduced as a new index for prioritizing components for maintenance activities and budget allocation. The process of budget allocation is carried out without using any optimization method and just by multiplying the maintenance budget by this newly designed factor. A multi-attribute decision-making technique (MAXIMAX) is considered to find the appropriate weighting coefficient of failure causes to reduce the effect of human dependency in the modeling failure rate of each component. Based on the priority and amount of budget allocated, a reliability-centered maintenance program for the sample distribution system is designed and implemented. The proposed RMC framework was implemented to a part of a distribution network in Iran to highlight its effectiveness and practicality. The obtained results showed an improvement in reliability indexes, which in turn confirms that prioritizing component criticality in budget allocation and maintenance programming enables reaching the reliability goals. Improvement in reliability indexes leads to maintenance cost reduction in future time intervals and efficient management of limited resources. A further comparison analysis with other approaches have shown that the proposed framework outperforms these methods in terms of speed, accuracy and budget allocation.
We formulate and analyze a general reaction-diffusion equation with delay, inspired by age-structured spruce budworm population dynamics with spatial diffusion by matured individuals. The model has its particular feature for bistability due to the incorporation of a nonlinear birth function (Ricker's function) and a Holling type function of predation by birds. Here we establish some results about the global dynamics, in particular, the stability of and global Hopf bifurcation from the spatially homogeneous steady state when the maturation delay is taken as a bifurcation parameter. We also use a degree theoretical argument to identify intervals for the diffusion rate when the model system has a spatially heterogeneous steady state. Numerical experiments presented show interesting spatialtemporal patterns.
Active remote sensing by laser scanning (LiDAR) has markedly improved the mapping of a cave environment with an unprecedented level of accuracy and spatial detail. However, the use of laser intensity simultaneously recorded during the scanning of caves remains unexplored despite it having promising potential for lithological mapping as it has been demonstrated by many applications in open-sky conditions. The appropriate use of laser intensity requires calibration and corrections for influencing factors, which are different in caves as opposed to the above-ground environments. Our study presents an efficient and complex workflow to correct the recorded intensity, which takes into consideration the acquisition geometry, micromorphology of the cave surface, and the specific atmospheric influence previously neglected in terrestrial laser scanning. The applicability of the approach is demonstrated on terrestrial LiDAR data acquired in the Gouffre Georges, a cave located in the northern Pyrenees in France. The cave is unique for its geology and lithology allowing for observation, with a spectacular continuity without any vegetal cover, of the contact between marble and lherzolite rocks and tectonic structures that characterize such contact. The overall accuracy of rock surface classification based on the corrected laser intensity was over 84%. The presence of water or a wet surface introduced bias of the intensity values towards lower values complicating the material discrimination. Such conditions have to be considered in applications of the recorded laser intensity in mapping underground spaces. The presented method allows for putting geological observations in an absolute spatial reference frame, which is often very difficult in a cave environment. Thus, laser scanning of the cave geometry assigned with the corrected laser intensity is an invaluable tool to unravel the complexity of such a lithological environment.
The problem of constructing statistical intervals for two-parameter Maxwell distribution is considered. An appropriate method of finding the maximum likelihood estimators (MLEs) is proposed. Constructions of confidence intervals, prediction intervals and one-sided tolerance limits based on suitable pivotal quantities are described. Pivotal quantities based on the MLEs, moment estimators and the modified MLEs are proposed and compared the statistical intervals based on them in terms of expected widths. Comparison studies indicate that the statistical intervals based on the MLEs offer little improvements over other interval estimates when sample sizes are small, and all intervals are practically the same even for moderate sample sizes. R functions to compute various intervals are provided and the methods are illustrated using two examples involving real data sets.
Influences of multiple environmental factors on water quality patterns is less studied in large rivers. Landscape analysis, multiple statistical methods, and the water quality index (WQI) were used to detect water quality patterns and influencing factors in China's largest river, the Yangtze River. Compared with the dry season, the wet season had significantly higher total phosphorus (TP), chemical oxygen demand (COD), total suspended solids (TSS), and turbidity (TUR). The WQI indicated “Moderate” and “Good” water quality in the wet and dry seasons, respectively. Compared with other sites, the upper reach sites that immediately downstream of the Three Gorges Dam had lower TP, TN, TSS and TUR in both seasons, and had lower and higher water temperature in the wet and dry seasons, respectively. Water quality patterns were mainly driven by heterogeneity in land use (i.e., wetland, cropland, and urban land), hydrology (i.e., water flow, water level), and climate (i.e., rainfall, air temperature). Water quality in the wet season was primarily driven by land use while the joint effect of land use and hydrology primarily drove in the dry season. Decision-makers and regulators of large river basin management may need to develop programs that consider influences from both human and natural drivers for water quality conservation.
A minuscule fraction of the deep sea has been scientifically explored and characterized due to several constraints, including expense, inefficiency, exclusion, and the resulting inequitable access to tools and resources around the world. To meet the demand for understanding the largest biosphere on our planet, we must accelerate the pace and broaden the scope of exploration by adding low-cost, scalable tools to the traditional suite of research assets. Exploration strategies should increasingly employ collaborative, inclusive, and innovative research methods to promote inclusion, accessibility, and equity to ocean discovery globally. Here, we present an important step toward this new paradigm: a collaborative design study on technical capacity needs for equitable deep-sea exploration. The study focuses on opportunities and challenges related to low-cost, scalable tools for deep-sea data collection and artificial intelligence-driven data analysis. It was conducted in partnership with twenty marine professionals worldwide, covering a broad representation of geography, demographics, and domain knowledge within the ocean space. The results of the study include a set of technical requirements for low-cost deep-sea imaging and sensing systems and automated image and data analysis systems. As a result of the study, a camera system called Maka Niu was prototyped and is being field-tested by thirteen interviewees and an online AI-driven video analysis platform is in development. We also identified six categories of open design and implementation questions highlighting participant concerns and potential trade-offs that have not yet been addressed within the scope of the current projects but are identified as important considerations for future work. Finally, we offer recommendations for collaborative design projects related to the deep sea and outline our future work in this space.
Phymatolithon Foslie is one of the most studied and ecologically important genera of crustose coralline algae (CCA) due to their dominant abundance in various marine ecosystems worldwide. The taxonomy of the genus is complex and has been revised and updated many times based on morphological and molecular analyses. We report on a crustose coralline algal species collected in June 2011 via snorkeling in the subtidal zone along the beach Abu Qir on the Mediterranean coast of Egypt, as part of a larger macroalgal diversity survey in the region. The species shows significant sequence divergences (3.5%–14.8% in rbc L; 2.9%–11% in psb A) from other closely related Phymatolithon taxa. Morpho-anatomically, this species possesses the characters considered collectively diagnostic of the genus Phymatolithon , namely, thalli non-geniculate epithelial cells and non-photosynthetic and domed-shaped meristematic cells, usually as short with progressive elongation of their perithallial derivatives. Based on molecular and morphological analyses, we determined that these specimens encompass a new, distinct species that we herein name Phymatolithon abuqirensis. Including this new species, the total number of described Phymatolithon species found in the Mediterranean Sea is now six.
The ultra-high temperature characteristic of the deep closed-loop geothermal system poses a great challenge for drilling. This paper proposes a reelwell drilling method for temperature-controlled drilling in ultra-high temperature geothermal reservoirs. Combining the flow characteristics and heat transfer mechanisms in each flow channel under three circulating modes of reelwell drilling, a set of integrated transient heat transfer models is developed for distinct thermal-associated regions. The model simultaneously couples the effect of the variable temperature-mass flow resulting from the fluid transition in different flow channels. The finite difference method is used to solve the model, and the field measurement data is employed to validate the model. The heat transfer rate and wellbore temperature distribution in reelwell drilling are investigated, and the optimum circulating mode suitable for temperature-controlled drilling is optimized. The results indicate that the cumulative bottomhole heat flux is always negative in reelwell drilling, revealing that the bottomhole temperature decreases gradually. Additionally, the absolute values of the cumulative heat flux under different circulating modes are consistent with circulating mode B > conventional drilling > circulating mode C > circulating mode A. Thus, the circulating mode B can effectively reduce the bottomhole temperature during drilling directional well. Moreover, when a suitable dual-channel valve position is selected in the middle and lower part of the wellbore and the auxiliary fluid inlet temperature is controlled to be less than 20 °C, the circulating mode B has the best temperature-controlled effect. Therefore, the circulating mode B of reelwell drilling method can provide a new option for temperature-controlled drilling for the deep closed-loop geothermal system.
School-based assessments of students' self-reported social-emotional competencies (SECs) are an essential part of social and emotional learning (SEL) initiatives. Few studies, however, have investigated whether such assessments align with the frameworks that inform SEL practices, especially for diverse populations. In the present study we investigated the dimensional structure of the 40-item Washoe County School District Social-Emotional Competency Assessment (WCSD-SECA), which was designed to measure the five domains of SECs defined by the widely used Collaborative for Academic Social and Emotional Learning framework (CASEL 5). Findings showed that a subset of 21 items fit a 3-factor solution that reflected Intrapersonal, Interpersonal, and Emotion-Focused competencies, a structure consistent with previous theorizing of broad SEC constructs. This 3-dimensional structure was partially invariant, with differences especially evident in item thresholds across subpopulations (defined by the intersection of grade level, gender, and race/ethnicity). Accounting for differences in item thresholds increased mean differences among subpopulations in the three domains. Across subpopulations, Intrapersonal scores were positively associated with students' standardized test scores and GPAs, and negatively related to the number of days they were absent from school, in multilevel models that adjusted for school-level clustering and included all three SEC scores and student demographic controls. Interpersonal scores were associated with fewer suspensions. Interpersonal and Emotion-Focused scores demonstrated unexpectedly negative associations with some outcomes in these models. Findings contribute to an emerging body of research that aims to deepen understandings of the content and structure of students' SECs as well as the factors that contribute to growth in these competencies.
Aquifer storage and recovery (ASR) is an important water management approach to store excess surface water into aquifers for later use. Quantitative evaluation of ASR performance is not a trivial task and yet becomes more exacting when uncertainty analysis is added to the dimensionality of the problem. Inclusion of uncertainty into the framework of scheduling optimal ASR operations also increases the level of complexity. This study integrates a surrogate modeling approach coupled with a mixed integer nonlinear programming (MINLP) algorithm to optimize multi-objective ASR operations. The uncertainties are analyzed based upon a thorough sampling of the parameters space as well as a novel analysis of Pareto fronts and variograms of representative solutions. Knee point of representative Pareto fronts is selected for in-depth analysis. As a solution to the dimensionality of the problem, Artificial Neural Network (ANN) is employed to generate surrogate models for predicting groundwater levels and injectate distribution within the aquifer during ASR operations. The computational complexity in building a large number of ANNs and deriving of numerous Pareto fronts via solving the MINLP problem are overcome by the assistance of parallel computing. The results show that optimal ASR operations are highly influenced by hydraulic conductivity and longitudinal dispersivity. Higher hydraulic conductivity values lead to a higher number of active stress periods during storage and recovery phases, which requires large volume of extraction to recover the dispersed injectate. In contrast, higher ratios of longitudinal dispersivity to hydraulic conductivity adversely impact the injectate recovery efficiency. Through meaningful representation of objective function uncertainty by variograms, it is inferred that injectate recovery efficiency is more sensitive to longitudinal dispersivity than hydraulic conductivity.
In this study, activation of peroxymonosulfate (PMS) by amorphous FeOOH to degrade sulfamethoxazole (SMX) was investigated. The amorphous FeOOH showed a better performance in the decomposition of PMS and the degradation of SMX than the crystallized α-FeOOH and β-FeOOH. The quenching experiments and EPR measurements suggested that the mechanism of PMS activation by amorphous FeOOH was mainly the surface-bound radicals (●OH and SO4●-). Basically, the surface-bound ●OH radicals were the dominate reactive oxide species in this system, which were mainly generated via the decomposition of amorphous FeOOH-PMS complexes. The degradation of SMX was significantly inhibited with the presence of H2PO4⁻, and this adverse impact was negligibly affected by the increase of H2PO4⁻ concentration, implying that the inhibition of SMX degradation was caused by competitive adsorption. Consequently, the Fe–OH bonds on the amorphous FeOOH were proposed as the reactive sites for forming amorphous FeOOH-PMS complexes. Besides, the amorphous FeOOH showed a better performance in the degradation of SMX in the acid conditions than that in the base conditions due to the surface charge of amorphous FeOOH. More importantly, the reduction efficiency of Fe(III) was significantly enhanced due to the excellent conductivity of amorphous FeOOH.
Former NBA all-star forward Rasheed Wallace popularized the catchphrase “Ball Don’t Lie.” Rasheed would often shout this after an opponent missed a free throw. It was used by Rasheed to illustrate the mental impact on a free throw shooter from knowing the foul was questionable and its impact on likelihood of converting the ensuing free throw. The tendency to miss free throws associated with questionable foul calls—or the propensity for the ball to miss—would be followed by Rasheed’s “Ball Don’t Lie!” exclamation. This paper aims to test whether the ball was less likely to go through the hoop during free throws following questionable foul calls. We use a proxy to identify the questionableness of a foul call, one that Rasheed Wallace was very familiar with—whenever the original shooting foul was immediately followed by a technical foul. This proxy is meant to capture player and coach reactions to a shooting foul call. If the call was bad, or questionable, we expect more outrage from the team the foul was called on, which tends to draw technical fouls. Our findings do not support Rasheed’s prediction; the propensity to make a shooting foul free throw does not appear to change after a technical. In fact, using a subset of our data period under which the NBA changed technical foul rules to target complaining about foul calls, we find a small increase in free throw percentage after a technical foul call.
Objective: As novice teen drivers are uniquely susceptible to the harmful effects of secondary activities on cellphones, 38 states and Washington D.C. have banned all types of cellphone usage for drivers younger than 18 years or in the learner/intermediate phase of driving. Despite the prevalence of such cellphone prohibitions, several surveillance studies have highlighted the persistent engagement of teenagers in cellphone-distracted driving, which increases the related crash risk. Most of the prior studies broadly consider cellphone usage as a general distraction instead of investigating different distraction-related tasks associated with cellphone use. This study analyzed the cellphone crashes of novice teenagers (aged 15-17 years) to discover the grouping of contributing factors by crash severity levels and cellphone usage types. Methods: The current study collected five years (2015-2019) of related crash data from the Louisiana Department of Transportation and Development. A manual effort was carried out to recognize the type of cellphone tasks before collision by reading the narratives of police-investigated crash reports. Association rule mining was applied to explore the associations between numerous crash attributes in multiple circumstances without relying on any predetermined hypotheses. Results: The cumulative effect of cellphone distraction and no seatbelt usage is frequently visible in confirmed injury crash scenarios. Cellphone crashes of novice teenagers at intersections are strongly associated with talking/listening rather than texting/browsing/dialing and reaching for/answering/locating. The associations among environmental factors and modes of cellphone usage significantly influence the manner of collisions. Single-vehicle crashes are associated with cellphone manipulation while driving on weekends in cloudy weather, whereas sideswipe collisions are frequent in evening hours during reaching for/answering/locating the cellphones. In relation to texting/browsing/dialing, novice teenagers operating vans/SUVs are strongly associated with traffic control violations. Conclusions: The findings are expected to be beneficial for policymakers and other safety officials to develop strategic planning and implementable countermeasures when dealing with cellphone-distracted novice teenagers. The association of factors identified from the analysis exhibits real-world crash scenarios critical to strengthening driver education programs to mitigate teen driver crashes. Moreover, cellphone crashes and related casualties can be reduced by eliminating or improving one of the attributes involved in the crash patterns.
Heterospecific disturbance in seabird colonies can negatively influence reproductive success both through direct effects, such as predation, and through indirect effects, such as increasing parental energy expenditure via defense behaviors. Here, remote nest cameras were used to evaluate the effects of intrusion on early nest survival and predation risk in Roseate Tern (Sterna dougallii) colonies in the U.S. and British Virgin Islands. Effects of colony traits such as colony size on parental nest defense were also investigated to assess individual response to predator presence in colonies. We counted 141 intrusion events at 118 nests and found that frequency of heterospecific disturbance did not influence nest survival, but did have a positive association with predation rate. Disturbance decreased significantly with colony size and % cover, and disturbance increased with nest density, indicating that concealed, isolated nests within large colonies were less likely to be disturbed. Parental nest defense decreased significantly with colony size and nest density. Results were likely driven by the dominant predator types in our systemlarge predatory birds and invasive ratsas parents were more likely to leave nests with intrusion from these predator types.
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3,958 members
Paul L Klerks
  • Department of Biology
Raymond Bauer
  • Department of Biology
Masood Sepehrimanesh
  • Department of Biology
Shuichi Sato
  • Department of Kinesiology
Sugata Sanyal
  • School of Computing and Informatics, University of Louisiana at Lafayette's Ray P. Authement College of Sciences, USA.
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