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Articles 38911 - 38940 of 291657

Full-Text Articles in Physical Sciences and Mathematics

Soil Moisture Migration Mechanism And Its Ecological Effect In Cold And Arid Open-Pit Coal Mining Area, Wang Qiangmin, Zhao Chunhu, Wang Hao, Sun Jie, Yang Jian, Wang Wenke Jun 2023

Soil Moisture Migration Mechanism And Its Ecological Effect In Cold And Arid Open-Pit Coal Mining Area, Wang Qiangmin, Zhao Chunhu, Wang Hao, Sun Jie, Yang Jian, Wang Wenke

Coal Geology & Exploration

In order to explore the soil moisture migration mechanism and its ecological effect in the cold and arid open-pit coal mining area, a long-term in-situ test was carried out to observe the soil moisture, taking the open-pit coal mine in eastern Mongolia grassland area as the study area. The results show that: The shallow soil moisture content is mainly affected by rainfall in non-freezing period, while the soil moisture content is significantly affected by soil temperature in freezing period. Besides, the saturated permeability coefficient of soil in depth less than 50 cm is greater than 150 cm/d, but that of …


Investigating The Activity Of Alternative Warheads For Targeted Covalent Inhibition Of The Inhibitor Vertebrate Lysozyme Protein From Pseudomonas Aeruginosa, Katie Hambrick Jun 2023

Investigating The Activity Of Alternative Warheads For Targeted Covalent Inhibition Of The Inhibitor Vertebrate Lysozyme Protein From Pseudomonas Aeruginosa, Katie Hambrick

Master of Science in Chemical Sciences Theses

Pseudomonas aeruginosa (P. aeruginosa) is a Gram-negative bacterium that causes blood and lung infections in hospital environments due to its ability to survive on improperly sterilized medical equipment. P. aeruginosa has developed several multi-drug resistance mechanisms that make it very difficult to treat with current antibiotics.1 This presents the need for a new class of antibiotics that cannot be overcome by P. aeruginosa’s mechanisms of resistance.

The primary goal of this project was to develop a small library of inhibitors that could later be incorporated into lead compounds for novel antibiotic drug discovery. One of P. …


Study Of Antioxidant Activity Of The Derivatives Of Quinoline-4-Carboxylic Acids By The Modification Of Isatin Via Pfitzinger Reaction, Sakti Hidayati Fikriya, Antonius Herry Cahyana Jun 2023

Study Of Antioxidant Activity Of The Derivatives Of Quinoline-4-Carboxylic Acids By The Modification Of Isatin Via Pfitzinger Reaction, Sakti Hidayati Fikriya, Antonius Herry Cahyana

Makara Journal of Science

In this study, a quinoline-4-carboxylic acid derivative was synthesized through Pfitzinger reaction. In this reaction, isatin is modified via its reaction with ketone and refluxed for 24 h to obtain quinoline-4-carboxylic acid. The presence of a carboxylic group was identified by Fourier Transform Infrared (FTIR) spectroscopy and ultraviolet–visible (UV-Vis) spectrophotometry. The results showed that the absorption peaks of C=O and O–H stretching’s were detected in the range of 1724–1708 and 3436–3242 cm−1, respectively. In the UV-vis spectrum, a shift in the absorption peak was observed toward a larger wavelength, which is referred as a bathochromic shift. The formation …


Comparing Visitor Perceptions, Characteristics, And Support For Management Actions Before And During A Pilot Timed Entry System At Arches National Park, Zachary D. Miller, Amy Tendick, Caleb Meyer, David Pettebone, Bret Meldrum, Steve Lawson Jun 2023

Comparing Visitor Perceptions, Characteristics, And Support For Management Actions Before And During A Pilot Timed Entry System At Arches National Park, Zachary D. Miller, Amy Tendick, Caleb Meyer, David Pettebone, Bret Meldrum, Steve Lawson

Environment and Society Student Research

Over the past decade, many national park units in the United States broke visitation records. Arches National Park (UT, USA) is no exception. Between 2011 and 2021, visitation increased 74%. As part of considering management options to address the issues from sustained and concentrated visitation, Arches implemented a pilot timed entry system from 3 April to 3 October 2022. This article compares visitor perceptions, characteristics, and support for management actions before and during the pilot timed entry system using data from visitor intercept surveys. Findings suggest visitors experience quality improved across the park and on hiking trails during the pilot …


Design, Development And Implementation Of A Comprehensive Evaluation System For Multi-Source Information On Water Inrush From Coal Seam Floor, Li Bo, Luo Yulan, Fan Juan, Guo Xiaoming, Li Menghua Jun 2023

Design, Development And Implementation Of A Comprehensive Evaluation System For Multi-Source Information On Water Inrush From Coal Seam Floor, Li Bo, Luo Yulan, Fan Juan, Guo Xiaoming, Li Menghua

Coal Geology & Exploration

The evaluation technology of multi-source information fusion is an important method for the prediction of water inrush from the coal seam floor. However, this method has the deficiencies, such as high professional technical requirements, complicated and tedious evaluation process, and insufficient intelligence during its application. In this study, the design principle, design idea, development mode, and development method of a multi-source information comprehensive evaluation system for water inrush from coal seam bottom were systematically described according to the characteristics of the technical process of water inrush risk evaluation. The key functions of system were built, including the universal evaluation index …


Mine Water Inrush Prediction Method Based On Vmd-Dbn Model, Liu Hui, Liu Guiqin, Ning Dianyan, Fan Juan, Chen Weiming Jun 2023

Mine Water Inrush Prediction Method Based On Vmd-Dbn Model, Liu Hui, Liu Guiqin, Ning Dianyan, Fan Juan, Chen Weiming

Coal Geology & Exploration

In the process of coal mining, the loss of people and property caused by mine water inrush is extremely serious. To prevent the occurrence of water inrush accidents and grasp the law of change of water inrush, the water inrush prediction and forecasting, especially the accurate estimation of mine water inrush, is very important, which is also an important task in the prevention and control of mine water damage. To increase the prediction accuracy of mine water inrush, an efficient time series prediction model combining Variational Mode Decomposition (VMD) and Deep Belief Network (DBN) was proposed for the series of …


Numerical Simulation Of Grout Diffusion Under Coal Seam Floor And Analysis Of Influencing Factors, Guo Yan, Gui Herong, Wei Jiuchuan, Hong Huang, Guo Xiangdong, Cui Yali, Ye Shuang, Li Jun Jun 2023

Numerical Simulation Of Grout Diffusion Under Coal Seam Floor And Analysis Of Influencing Factors, Guo Yan, Gui Herong, Wei Jiuchuan, Hong Huang, Guo Xiangdong, Cui Yali, Ye Shuang, Li Jun

Coal Geology & Exploration

Ground high-pressure advanced regional grouting has become the preferred engineering method for the prevention and control of water disasters in coal mines. The diffusion mechanism of grout has received widespread attention, and the design of branch hole spacing mostly relies on the on-site experience, which has a certain degree of blindness and restricts the effectiveness and efficiency of the project. Based on the actual working conditions of grouting site in Hengyuan Coal Mine, Huaibei Coalfield, the numerical simulation was performed with the COMSOL Multiphysics software for the high-pressure grout diffusion in the floor area of the ground directional drilling coal …


Design And Application Of The 3d Model Interfaces Of The Integrated Intelligent Mine Control Platform, Zhang Jing Jun 2023

Design And Application Of The 3d Model Interfaces Of The Integrated Intelligent Mine Control Platform, Zhang Jing

Coal Geology & Exploration

The production safety control platform for mines is used to present information on the centralized scheduling, real-time monitoring, risk prevention and control, operation and maintenance detection, and decision analysis of various equipment and automated, intelligent production systems for tunneling, mining, machinery, transportation, and ventilation during coal mine production. Accordingly, the interface design of the integrated intelligent mine control platform is particularly important for user experience. However, the current integrated automation systems for mines adopt monochrome configuration engineering plans and display a single interface effect of display and operation. By introducing the industrial design concepts and employing the 3D model interface …


Influence Of Water Yield Property Of Yan’An Formation Aquifer On Water Yield Of Mines In Southern Shenmu-Fugu Mining Area, Li Shu, Yang Zeyuan, Ma Xiongde, Liu Shengzu, Fang Chujing, Zhang Aoqi Jun 2023

Influence Of Water Yield Property Of Yan’An Formation Aquifer On Water Yield Of Mines In Southern Shenmu-Fugu Mining Area, Li Shu, Yang Zeyuan, Ma Xiongde, Liu Shengzu, Fang Chujing, Zhang Aoqi

Coal Geology & Exploration

Aiming at the large difference of water yield of different mine fields in Yushenfu mining area, based on a large amount of drilling, pumping test data collected in the area, from the weathering and denudation, burning effect, discontinuous distribution regions of aquifuges, microscopic pore structure, the influencing factors of water yield property of Yan’an Formation aquifer(YFA) are analyzed. Combined with the height of the water-conducting fissure zones, the influence of water yield property of YFA on water yield of mines is discussed. The results show that weathering and denudation cause the sandstone of Yan’an Formation to develop fissures and be …


A Method For Predicting Fractures In Carbonate Reservoirs Based On Fracture Identification-Sensitive Log-Seismic Parameter Model, Wang Zhiwei, Zhang Kai, Wu Qunhu, Zhang Benhua, Yu Shina, Zhang Zunxiang, Wu Yanjia Jun 2023

A Method For Predicting Fractures In Carbonate Reservoirs Based On Fracture Identification-Sensitive Log-Seismic Parameter Model, Wang Zhiwei, Zhang Kai, Wu Qunhu, Zhang Benhua, Yu Shina, Zhang Zunxiang, Wu Yanjia

Coal Geology & Exploration

Carbonate reservoirs show fractures and strong heterogeneity, leading to limited applications of a single logging or seismic method in fracture identification. Therefore, this study proposed a method for predicting fractures in carbonate reservoirs based on a fracture identification-sensitive log-seismic parameter (FISLSP) model, and the details are as follows: (1) Based on petrophysical analysis results, as well as formation micro-imaging (FMI) logs and the interpretations of fractures at well locations, this study established a segmental fracture identification-sensitive parameter (FISP) model for fractures at well locations; (2) Using the optimal seismic attributes of near-well seismic traces determined based on the high-quality fractured …


Application And Prospect Of Acoustic Detection In The Mining Sector, Deng Jun, Wang Jinrui, Ren Shuaijing, He Qian, Wang Caiping, Qu Gaoyang Jun 2023

Application And Prospect Of Acoustic Detection In The Mining Sector, Deng Jun, Wang Jinrui, Ren Shuaijing, He Qian, Wang Caiping, Qu Gaoyang

Coal Geology & Exploration

Acoustic detection for mines is a geophysical prospecting technique for mine information detection based on acoustic methods. Compared with other detection methods, acoustic detection has the advantages of wide applicability, high reliability, and low economic investment. This paper reviews the development of acoustic detection technology in the mine field and sorts out and expounds on the research progress and technical characteristics of this technology in detecting basic physical information inside mines and geological information outside mines. Furthermore, this study investigates the detection mechanisms, implementation methods, and applicable scenarios of this technology in determining the object states in the field of …


Study On Modification Of Plant Gum Flushing Fluid In Coal-Bearing Strata And Its Mechanism, Xie Chengchao, Wang Sheng, Yan Peng, Chen Liyi, Li Bingle, Zhang Jie Jun 2023

Study On Modification Of Plant Gum Flushing Fluid In Coal-Bearing Strata And Its Mechanism, Xie Chengchao, Wang Sheng, Yan Peng, Chen Liyi, Li Bingle, Zhang Jie

Coal Geology & Exploration

To improve the adverse effects of the depletion of plant gum resources on the application of flushing fluid in complex strata such as coal-bearing strata, a study was conducted on the compound and crosslinking modification of guar gum. A new type of plant gum flushing fluid (GXB) was developed using xanthan gum as the compound synergist and organic boron as the crosslinking modifier, with cross-linking control agent and inorganic treatment agent as the supplementary. Meanwhile, a series of performance evaluation was carried out. The evaluation results show that GXB has excellent performance and can meet the requirements of drilling in …


Assessing Downstream Aquatic Habitat Availability Relative To Headwater Reservoir Management In The Henrys Fork Snake River, Christina N. Morrisett, Robert W. Van Kirk, Sarah E. Null Jun 2023

Assessing Downstream Aquatic Habitat Availability Relative To Headwater Reservoir Management In The Henrys Fork Snake River, Christina N. Morrisett, Robert W. Van Kirk, Sarah E. Null

Watershed Sciences Student Research

Reservoirs are sometimes managed to meet agricultural and other water demands, while also maintaining streamflow for aquatic species and ecosystems. In the Henrys Fork Snake River, Idaho (USA), irrigation-season management of a headwater reservoir is informed by a flow target in a management reach ~95 km downstream. The target is in place to meet irrigation demand and maintain aquatic habitat within the 11.4 km management reach and has undergone four flow target assignments from 1978 to 2021. Recent changes to irrigation-season management to maximize reservoir carryover warranted investigation into the flow target assignment. Thus, we created a streamflow-habitat model using …


Effects Of Increasing Sintering Pressure On The Performance Of Impregnated Diamond Bit, Yang Zhan, Tan Songcheng, Fang Xiaohong, Yang Kaihua Jun 2023

Effects Of Increasing Sintering Pressure On The Performance Of Impregnated Diamond Bit, Yang Zhan, Tan Songcheng, Fang Xiaohong, Yang Kaihua

Coal Geology & Exploration

The matrix formulas of conventional hot-pressed impregnated diamond bits are mostly elemental metal systems, using WC or YG8 as the skeleton materials, Cu alloys as the bonding materials, and Ni, Co, Fe and Mn as the intermediate materials. Due to the compositions and contents of the bonding and skeleton materials in the formulas, the suitable sintering pressure is limited (≤16 MPa), while the sintering temperature is relatively high (≥ 930℃), resulting in a lower relative ratio of the actual and theoretical densities (≤98%) for the diamond bit matrix. However, the high sintering temperature will cause thermal damage to the diamonds, …


Measurements Of Jet Multiplicity And Jet Transverse Momentum In Multijet Events In Proton–Proton Collisions At √S = 13tev, A. Tumasyan Jun 2023

Measurements Of Jet Multiplicity And Jet Transverse Momentum In Multijet Events In Proton–Proton Collisions At √S = 13tev, A. Tumasyan

Department of Physics and Astronomy: Faculty Publications

Multijet events at large transverse momentum (pT) are measured at √ s = 13 TeV using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 36.3 fb−1. The multiplicity of jets with pT > 50 GeV that are produced in association with a high-pT dijet system is measured in various ranges of the pT of the jet with the highest transverse momentum and as a function of the azimuthal angle difference Δφ1,2 between the two highest pT jets in the dijet system. The differential production …


Deep Learning Enhancement And Privacy-Preserving Deep Learning: A Data-Centric Approach, Hung S. Nguyen Jun 2023

Deep Learning Enhancement And Privacy-Preserving Deep Learning: A Data-Centric Approach, Hung S. Nguyen

USF Tampa Graduate Theses and Dissertations

Deep Learning and its applications have become attractive to a lot of research recentlybecause of its capability to capture important information from large amounts of data. While most of the work focuses on finding the best model parameters, improving machine learning performance from data perspective still needs more attention. In this work, we propose techniques to enhance the robustness of deep learning classification by tackling data issue. Specifically, our data processing proposals aim to alleviate the impacts of class-imbalanced data and non- IID data in deep learning classification and federated learning scenarios. In addition, data pre-processing strategies such that dimensionality …


Symbiotic Ucyn-A Strains Co-Occurred With El Niño, Relaxed Upwelling, And Varied Eukaryotes Over 10 Years Off Southern California, Colette Fletcher-Hoppe, Yi-Chun Yeh, Yubin Raut, J. L. Weissman, Jed A. Fuhrman Jun 2023

Symbiotic Ucyn-A Strains Co-Occurred With El Niño, Relaxed Upwelling, And Varied Eukaryotes Over 10 Years Off Southern California, Colette Fletcher-Hoppe, Yi-Chun Yeh, Yubin Raut, J. L. Weissman, Jed A. Fuhrman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

Biological nitrogen fixation, the conversion of N2 gas into a bioavailable form, is vital to sustaining marine primary production. Studies have shifted beyond traditionally studied tropical diazotrophs. Candidatus Atelocyanobacterium thalassa (or UCYN-A) has emerged as a focal point due to its streamlined metabolism, intimate partnership with a haptophyte host, and broad distribution. Here, we explore the environmental parameters that govern UCYN-A’s presence at the San Pedro Ocean Time-series (SPOT), its host specificity, and statistically significant interactions with non-host eukaryotes from 2008-2018. 16S and 18S rRNA gene sequences were amplified by “universal primers” from monthly samples and resolved into Amplicon …


Beyond The Ice, Nikolaus T. Butz, Joshua Hunter, Emma Fisher Jun 2023

Beyond The Ice, Nikolaus T. Butz, Joshua Hunter, Emma Fisher

The Journal of Values-Based Leadership

Leadership is a management tool to direct effective achievement of goals. Historical investigation can provide a valuable lens for the study of leadership styles. To that end, this study examines the disparate approaches of Roald Amundsen and Robert Scott as they raced to be the first explorer to reach the South Pole. The objective of this study is to analyze the leadership techniques used in these expeditions, and to determine how they shaped the outcome of each. The process of tacit knowledge and experience coalesce and foster both leadership and action that is not only communication-oriented and value-driven, but also …


Possible Attacks On Match-In-Database Fingerprint Authentication, Jadyn Sondrol Jun 2023

Possible Attacks On Match-In-Database Fingerprint Authentication, Jadyn Sondrol

Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal

Biometrics are used to help keep users’ data private. There are many different biometric systems, all dealing with a unique attribute of a user, such as fingerprint, face, retina, iris and voice recognition. Fingerprint biometric systems, specifically match-in-database, have universally become the most implemented biometric system. To make these systems more secure, threat models are used to identify potential attacks and ways to mitigate them. This paper introduces a threat model for match-in-database fingerprint authentication systems. It also describes some of the most frequent attacks these systems come across and some possible mitigation efforts that can be adapted to keep …


Probing As A Technique To Understand Abstract Spaces, Ashlen A. Plasek Jun 2023

Probing As A Technique To Understand Abstract Spaces, Ashlen A. Plasek

Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal

Machine learning models, while very powerful, have their operation obfuscated behind millions of parameters. This obfuscation can make deriving a human meaningful process from a machine learning model very difficult. However, while the intermediate states of a machine learning model are similarly obfuscated, using probing, we can start to explore looking at possible structure in those intermediate states. Large language models are a prime example of this obfuscation, and probing can begin to allow novel experimentation to be performed.


Deep-Learning Realtime Upsampling Techniques In Video Games, Biruk Mengistu Jun 2023

Deep-Learning Realtime Upsampling Techniques In Video Games, Biruk Mengistu

Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal

This paper addresses the challenge of keeping up with the ever-increasing graphical complexity of video games and introduces a deep-learning approach to mitigating it. As games get more and more demanding in terms of their graphics, it becomes increasingly difficult to maintain high-quality images while also ensuring good performance. This is where deep learning super sampling (DLSS) comes in. The paper explains how DLSS works, including the use of convolutional autoencoder neural networks and various other techniques and technologies. It also covers how the network is trained and optimized, as well as how it incorporates temporal antialiasing and frame generation …


Lidar Segmentation-Based Adversarial Attacks On Autonomous Vehicles, Blake Johnson Jun 2023

Lidar Segmentation-Based Adversarial Attacks On Autonomous Vehicles, Blake Johnson

Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal

Autonomous vehicles utilizing LiDAR-based 3D perception systems are susceptible to adversarial attacks. This paper focuses on a specific attack scenario that relies on the creation of adversarial point clusters with the intention of fooling the segmentation model utilized by LiDAR into misclassifying point cloud data. This can be translated into the real world with the placement of objects (such as road signs or cardboard) at these adversarial point cluster locations. These locations are generated through an optimization algorithm performed on said adversarial point clusters that are introduced by the attacker.


Not-So-Super Superfund: Cercla’S Biggest Issues, Cameron Berthiaume Jun 2023

Not-So-Super Superfund: Cercla’S Biggest Issues, Cameron Berthiaume

Scholarly Horizons: University of Minnesota, Morris Undergraduate Journal

The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA/Superfund) is a federal law that allows the Environmental Protection Agency (EPA) to clean up contaminated sites and hold the parties responsible for the contamination financially liable. However, CERCLA faces a number of challenges to fulfilling its mission. This report examines some of the biggest issues facing the law in the past and present.


An Introduction To Consumptive Use Of Water In South Carolina, Heather Bergerud Nix, Mani Rouhi Rad Jun 2023

An Introduction To Consumptive Use Of Water In South Carolina, Heather Bergerud Nix, Mani Rouhi Rad

Journal of South Carolina Water Resources

Effective water resource management requires understanding the supply of and the demand for water. In South Carolina, as in other places, water demand is often determined using total withdrawal volumes. However, the volume of water that is withdrawn can be significantly different from the volume that is actually consumed, which becomes unavailable for downstream uses. Water used for energy generation is commonly excluded from evaluations of total withdrawal volume because it is often assumed to be no or low consumptive use, meaning much of the withdrawn water is returned to the source and remains available for downstream uses. Additionally, energy …


Cauchy-Type Integral Method For Solving The Linearized One-Dimensional Vlasov-Poisson Equation, Frank M. Lee, Bradley A. Shadwick Jun 2023

Cauchy-Type Integral Method For Solving The Linearized One-Dimensional Vlasov-Poisson Equation, Frank M. Lee, Bradley A. Shadwick

Department of Physics and Astronomy: Faculty Publications

We present a method for solving the linearized Vlasov-Poisson equation, based on analyticity properties of the equilibrium and initial condition through Cauchy-type integrals, that produces algebraic expressions for the distribution and field, i.e., the solution is expressed without integrals. Standard extant approaches involve deformations of the Bromwich contour that give erroneous results for certain physically reasonable configurations or eigenfunction expansions that are misleading as to the temporal structure of the solution. Our method is more transparent, lacks these defects, and predicts previously unrecognized behavior.


Comment On “Search For Explanation Of The Neutron Lifetime Anomaly”, F. E. Wietfeldt, R. Biswas, J. Caylor, Bret E. Crawford, M. S. Dewey, N. Fomin, G. L. Greene, C. C. Haddock, S. F. Hoogerheide, H. P. Mumm, J. S. Nico, W. M. Snow, J. Zuchegno Jun 2023

Comment On “Search For Explanation Of The Neutron Lifetime Anomaly”, F. E. Wietfeldt, R. Biswas, J. Caylor, Bret E. Crawford, M. S. Dewey, N. Fomin, G. L. Greene, C. C. Haddock, S. F. Hoogerheide, H. P. Mumm, J. S. Nico, W. M. Snow, J. Zuchegno

Physics and Astronomy Faculty Publications

We respond to issues raised by Serebrov et al. in a recent paper regarding systematic effects in the beam neutron lifetime experiment performed at NIST. We show that these effects were considered in the original analyses and that our corrections and systematic uncertainties were appropriate. We point out some misunderstandings in the analysis of Serebrov et al. None of the issues raised lead us to alter the value of the neutron lifetime reported.


Analysis Of Ostds Failure Potential Due To Sea-Level Rise And Other Inundation Factors: An Integrated Geo-Spatial Analysis, Alec Colarusso Jun 2023

Analysis Of Ostds Failure Potential Due To Sea-Level Rise And Other Inundation Factors: An Integrated Geo-Spatial Analysis, Alec Colarusso

USF Tampa Graduate Theses and Dissertations

While many aspects of climate change are well-studied, the vulnerability of Onsite Sewage Treatment and Disposal Systems (OSTDS) to sea-level rise (SLR) has not been thoroughly examined despite the potentially significant environmental impacts, including nutrient and pathogen loading. Research gaps include the need to determine the suitability of models to predict groundwater inundation due to SLR and the consequent impact on OSTDS. As such, this study aims to compare Bathtub/hydrostatic and physics-based/MODFLOW/3D numerical modeling methods of simulating groundwater inundation from SLR to identify OSTDS vulnerability to failure due to a reduction in the height of the vadose zone (saturation or …


Optimal Estimation Inversion Of Ionospheric Electron Density From Gnss-Pod Limb Measurements: Part I-Algorithm And Morphology, Dong L. Wu, Nimalan Swarnalingam, Cornelius C. J. H. Salinas, Daniel J. Emmons, Tyler C. Summers, Robert Gardiner-Garden Jun 2023

Optimal Estimation Inversion Of Ionospheric Electron Density From Gnss-Pod Limb Measurements: Part I-Algorithm And Morphology, Dong L. Wu, Nimalan Swarnalingam, Cornelius C. J. H. Salinas, Daniel J. Emmons, Tyler C. Summers, Robert Gardiner-Garden

Faculty Publications

GNSS-LEO radio links from Precise Orbital Determination (POD) and Radio Occultation (RO) antennas have been used increasingly in characterizing the global 3D distribution and variability of ionospheric electron density (Ne). In this study, we developed an optimal estimation (OE) method to retrieve Ne profiles from the slant total electron content (hTEC) measurements acquired by the GNSS-POD links at negative elevation angles (ε < 0°). Although both OE and onion-peeling (OP) methods use the Abel weighting function in the Ne inversion, they are significantly different in terms of performance in the lower ionosphere. The new OE results can overcome the large Ne oscillations, sometimes negative values, seen in the OP retrievals in the E-region ionosphere. In the companion paper in this Special Issue, the HmF2 and NmF2 from the OE retrieval are validated against ground-based ionosondes and radar observations, showing generally good agreements in NmF2 from all sites. Nighttime hmF2 measurements tend to agree better than the daytime when the ionosonde heights tend to be slightly lower. The OE algorithm has been applied to all GNSS-POD data acquired from the COSMIC-1 (2006–2019), COSMIC-2 (2019–present), and Spire (2019–present) constellations, showing a consistent ionospheric Ne morphology. The unprecedented spatiotemporal sampling of the ionosphere from these constellations now allows a detailed analysis of the frequency–wavenumber spectra for the Ne variability at different heights. In the lower ionosphere (~150 km), we found significant spectral power in DE1, DW6, DW4, SW5, and SE4 wave components, in addition to well-known DW1, SW2, and DE3 waves. In the upper ionosphere (~450 km), additional wave components are still present, including DE4, DW4, DW6, SE4, and SW4. The co-existence of eastward- and westward-propagating wave4 components implies the presence of a stationary wave4 (SPW4), as suggested by other earlier studies. Further improvements to the OE method are proposed, including a tomographic inversion technique that leverages the asymmetric sampling about the tangent point associated with GNSS-LEO links.


Observation Of Robust Zero Energy Extended States, Jannatul Ferdous, Cem Yuce, Andrea Alu, Hamidreza Ramezani Jun 2023

Observation Of Robust Zero Energy Extended States, Jannatul Ferdous, Cem Yuce, Andrea Alu, Hamidreza Ramezani

Physics & Astronomy Faculty Publications

Topological edge states arise at the interface of two topologically distinct structures and have two distinct features: they are localized and robust against symmetry protecting disorder. On the other hand, conventional transport in one dimension is associated with extended states, which typically do not have topological robustness. In this letter, using lossy coupled resonators in one dimension, we demonstrate both theoretically and experimentally the existence of robust states residing in the bulk. We show that they are unusually robust against disorders in coupling between adjacent sites and losses. Our work paves the way to a different form of robust transport …


Study On Versatile S(Vi) Reagents Towards Synthesis Of S(Iv) And S(Vi) Functional Groups, Shun Teng Jun 2023

Study On Versatile S(Vi) Reagents Towards Synthesis Of S(Iv) And S(Vi) Functional Groups, Shun Teng

USF Tampa Graduate Theses and Dissertations

This dissertation mainly covers the latest methodology development in the field of sulfur-containing functional groups in synthetic chemistry. There are two parts. The first part is the asymmetric synthesis of sulfoximines, sulfonimidamides, sulfonimidoyl fluorides, and sulfinamides enabled by a versatile enantiopure S(VI) reagent. The second part is the Grignard reagent-triggered divergent S-editing synthesis via a bench-stable S(VI) reagent.

In the first part, the asymmetric synthesis of sulfoximines, sulfonimidamides, sulfonimidoyl fluorides, and sulfinamides is reported. This report focuses on the development of a bifunctional S(VI) reagent and its utility in synthesis. It employed the enhanced stability of sulfonimidoyl fluorides and the …