Engineering Commons^™

Critères De Stabilité Des Échelles Et Des Escabeaux, Bertrand Galy

Rapports de recherche scientifique

Les chutes de hauteur sont encore aujourd’hui une des principales causes d’accident au Québec, et la deuxième cause en termes de coûts sur la période 2010 – 2012, avec une moyenne de 397 millions de dollars par année. Selon la CNESST, les statistiques de lésions impliquant les échelles, que ce soit en construction ou en établissement, montrent une augmentation au fil des ans (période de 2007 à 2012) et sur la période 2009 à 2013, 20 % des lésions dues à une chute de hauteur ont été causées par une chute à partir d’une échelle.

Un des principaux critères affectant …

Analysis Of Computational Modeling Methods As Applied To Single-Crystal Organohalide Perovskites, Jon M. Bebeau

USF Tampa Graduate Theses and Dissertations

Perovskite, specifically MAPbI3, has exploded onto the electronic material forefront, with applications from photovoltaic to optical sensors. Still, there remain many unanswered questions about the electronic, structural and mechanical processes and properties of this perovskite. Computational software exists to model the electronic structure and material properties, to the nano scale, using density-functional theory. The goal of these models it to parallel the physical science of the substance in a computer simulation based on emerging mathematical models of the quantum mechanical behavior. In this study I review the historical use of perovskites in electronics, review the evolution of DFT algorithm developments …

Ramp Metering For A Distant Downstream Bottleneck Using Reinforcement Learning With Value Function Approximation, Yue Zhou, Kaan Ozbay, Pushkin Kachroo, Fan Zuo

Electrical & Computer Engineering Faculty Research

Ramp metering for a bottleneck located far downstream of the ramp is more challenging than for a bottleneck that is near the ramp. This is because under the control of a conventional linear feedback-type ramp metering strategy, when metered traffic from the ramp arrive at the distant downstream bottleneck, the state of the bottleneck may have significantly changed from when it is sampled for computing the metering rate; due to the considerable time, these traffic will have to take to traverse the long distance between the ramp and the bottleneck. As a result of such time-delay effects, significant stability issue …

Hateproofing Your Message: Response And Prevention Strategies For "Hatejacks", Bond Benton, Daniela Peterka-Benton

Department of Justice Studies Faculty Scholarship and Creative Works

No abstract provided.

An Inferential Study Of The Potential Consumer Value Of Free Charging For Users Of Public Electric Vehicle Charging Infrastructure, Divyamitra Mishra

USF Tampa Graduate Theses and Dissertations

Although there is economic and marketing evidence of consumers assigning additional benefits to free products and bundles, there is limited research into the behavioral consequences of offering public electric vehicle charging for free. Previous exploratory research by Maness and Lin analyzed possible economic and environmental benefits from offering free public charging infrastructure and policy. Their work found that providing free public charging infrastructure could increase plug-in electric vehicle sales and cause decreased reliance on fossil fuels in the personal transportation sector. However, their study assumed the increased value which consumers would place on free charge events. This project proposes to …

Using Reactive Dissipative Particle Dynamics To Understand Local Shape Manipulation Of Polymer Vesicles, Qinyu Zhu, Timothy R. Scott, Douglas R. Tree

Faculty Publications

Biological cells have long been of interest to researchers due to their capacity to actively control their shape. Accordingly, there is significant interest in generating simplified synthetic protocells that can alter their shape based on an externally or internally generated stimulus. To date, most progress has been made towards controlling the global shape of a protocell, whereas less is known about generating a local shape change. Here, we seek to better understand the possible mechanisms for producing local morphological changes in a popular protocell system, the block copolymer vesicle. Accordingly, we have combined Dissipative Particle Dynamics (DPD) and the Split …

Porous-Electrode Theory Of Lithium Ion Battery: Old Paradigm And New Challenge, Xiao-Xiao Wang, Zi-Rui Zhou, Qiang Shan, Zeng-Ming Zhang, Jun Huang, Yu-Wen Liu, Sheng-Li Chen

Journal of Electrochemistry

A critical review on the porous electrode theory developed by Newman and his colleagues is presented. We propose several ideas for further development of this theory by analyzing its limitations. The classical Newman theory does not consider ion steric effect in describing ion transport in electrolyte solutions, which can be amended by a newly developed ion-vacancy coupled charge transfer model for ion transport in concentrated solutions. Ion transport in solid particles of active materials is essentially an ion-electron coupled transport process, and its rationality is verified by comparing the calculated and experimental diffusion coefficients of Li ⁺ ion in intercalation …

Progress And Prospects On Multifunctional Coating Separators For Lithium-Sulfur Battery, Zhuang-Zhuang Wei, Nan-Xiang Zhang, Feng Wu, Ren-Jie Chen

Journal of Electrochemistry

The development of advanced energy storage systems is crucial to meet the growing demand for electric vehicles, portable devices and renewable energy storage. Lithium-sulfur (Li-S) batteries, with their advantages of high specific energy, low cost of raw materials and environmental friendliness, are hotspots in the research field of new high performance batteries. However, there are still many problems which hinder the practical applications of lithium-sulfur batteries, such as the shuttle effect of soluble polysulfide intermediates, the growth of lithium dendrites, and the thermal stability and safety of lithium-sulfur batteries during use. The design of multifunctional coating separator is one of …

Licoo2 As Sulfur Host To Enhance Cathode Volumetric Capacity For Lithium-Sulfur Battery, Lu Wang, Xue-Ping Gao

Journal of Electrochemistry

Lithium-sulfur battery is one of the most promising secondary battery systems due to its super high theoretical gravimetric and volumetric energy densities (2600 Wh·kg^-1 and 2800 Wh·L^-1, respectively). However, the practical volumetric capacity of sulfur cathode is still unsatisfied due to the overuse of low-density host materials, such as carbon nanomaterials. Herein, commercial LiCoO₂ with the high tap density of 2.94 g·cm^-3 was used as the host material to build high density sulfur-based composite and compact electrode for increasing the volumetric capacity. Obviously, the tap density of the as-prepared S/LiCoO₂ composite was 1.90 g·cm …

Research Progress Of Key Components In Lithium-Sulfur Batteries, Jia-Jia Chen, Quan-Feng Dong

Journal of Electrochemistry

Due to the much higher theoretical specific capacity and energy density than the ones of traditional lithium ion battery, Li-S batteries have long been at the pinnacle in the realms of high-energy Li-metal batteries. However, the complicated electrochemical reactions on the sulfur cathode and Li anode, induced by the thermodynamic and kinetic behaviors of lithium polysulfides, are the intrinsic bottleneck to realize the full potential of Li-S batteries for practical application. In this review, we firstly discuss the roles, and thermodynamic and kinetic behaviors of polysulfides in the charging and discharging processes of Li-S batteries. Then, the functional design and …

A Model For The Anodic Carbonization Of Alkaline Polymer Electrolyte Fuel Cells, Qi-Hao Li, Ying-Ming Wang, Hua-Long Ma, Li Xiao, Gong-Wei Wang, Jun-Tao Lu, Lin Zhuang

Journal of Electrochemistry

The alkaline polymer electrolyte fuel cell (APEFC) has made appreciable progress in recent years but is still suffering performance loss during discharge with air as the oxidant. Several theories have been suggested to interpret the loss. However, efforts are still needed to reach a clear quantitative understanding. Based on the major experimental findings in combination with thermodynamics and kinetics of the reactions involved in the anode, this paper presents a model featuring layered carbonization in the anode and relevant grouped equations. The simulation results generated from the latter are compared with experiments, and possible principles to suppress the performance loss …

Research Progress Of Sulfur Cathode Catalytic Conversions For Lithium-Sulfur Batteries, Qin-Jun Shao, Jian Chen

Journal of Electrochemistry

The electrochemical reduction of sulfur (S) takes place through multistep reactions when S is used as a cathode material. The complete discharge of S to form final product lithium sulfide (Li₂S) is a two-electron reaction. The formation of low-order lithium polysulfides (LiPS) needs to overcome certain energy barriers. And the reduction of Li₂S₂ to Li₂S is the rate-limited step. The reaction kinetic of sulfur cathode is the critical key to determine the electrochemical performance of Li-S batteries, such as specific energy, specific power and low temperature performance, etc. Accelerating the rate-limited step kinetics …

Cycling Performance And Solid-Electrolyte-Interphase Synergic Formation Of Silicon Nanoparticles In The Concentrated Electrolyte With Additives, Zeng-Hua Chang, Fu-Juan Han, Xi-Xin Yang, Jian-Tao Wang, Shi-Gang Lu

Journal of Electrochemistry

In this paper, the effects of additives on the cycling performance of silicon nanoparticles in LiFSI-(PC)₃ based concentrated electrolytes were systematically studied. The structures of silicon nanoparticle electrodes and the evolution of solid-electrolyte-interphase were characterized by scanning electron microscopy (SEM), attenuated total reflection Flourier transformed infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The results indicated that the additives can efficiently improve the cycling performance of silicon nanoparticle electrodes. In LiFSI-(PC)₃ concentrated electrolyte, the capacity became 574.8 mAh·g^-1 after 300 cycles with the initial capacity of 3296.1 mAh·g^-1. In contrast, the 3% LiDFOB, 3% FEC …

Liquid Metal Electrodes For Electrochemical Energy Storage Technologies, Hao-Miao Li, Hao Zhou, Kang-Li Wang, Kai Jiang

Journal of Electrochemistry

Electrochemical energy storage technologies (ESTs) with low cost, long lifespan and high safety are of great importance for efficient integration of renewable energy into the grid. Liquid metal electrodes (LMEs) possessing the merits of high electronic conductivity, easy manufacture and amorphous structure is of great application value in the field of energy storage batteries. During charge-discharge processing, the LMEs could avoid the issues of structural deformation and dendrite growth in solid metal electrodes, which could effectively extend the cycle life of the LME based batteries. Moreover, LME based batteries are easy to be scaled up and less expensive, which are …

Porous Electrodes In Electrochemical Energy Storage Systems, Wei-Xiao Ji, Gong-Wei Wang, Qiang Wang, Li-Jun Bai, De-Yang Qu

Journal of Electrochemistry

Professor C.S. Cha was among the pioneers who have introduced modern electrochemistry to China. Under his leadership, the electrochemical research group in Wuhan University became one of the global powerhouses in fundamental and applied electrochemical researches. During the past many decades, Professor Cha and his colleagues in the university have educated and trained many students who have become part of the backbone of electrochemistry worldwide. In this review, we demonstrate the solid foundation laid by Professor Cha and his colleagues in Wuhan University, and the advancements made in the area of porous electrodes by the authors. All the authors in …

Highly Efficient Co2 Utilization Via Molten Salt Co2 Capture And Electrochemical Transformation Technology, Bo-Wen Deng, Hua-Yi Yin, Di-Hua Wang

Journal of Electrochemistry

The molten electrolytes exhibit high CO₂ absorption capacities, wide electrochemical windows and excellent reaction kinetics, which are promising electrolyte candidates for efficient capture and electrochemical conversion of high-flux CO₂ driven by renewable and clean electricity sources. This short review introduces the recent advancements of CO₂ electroreduction achieved by the authors using molten salt CO₂ capture and electrochemical transformation (MSCC-ET) technology, involving CO₂ absorption kinetics, cathodic kinetics, controllable synthesis of carbon products with unique nanostructures, development of inert oxygen evolution anodes and CO₂ conversion efficiency as well as energy efficiency. The challenges and prospects are …

Fundamentals Of Distribution Of Relaxation Times For Electrochemical Impedance Spectroscopy, Jia Wang, Qiu-An Huang, Wei-Heng Li, Juan Wang, Quan-Chao Zhuang, Jiu-Jun Zhang

Journal of Electrochemistry

Electrochemical impedance spectroscopy (EIS) is a powerful electrochemical characterization technology, which has been widely used in the field of electrochemical energy, such as lithium-ion batteries, supercapacitors, fuel cells, etc. Distribution of relaxation time (DRT) is an EIS deconvolution technique which does not depend on the prior knowledge of the targeted research object. Furthermore, DRT can serve to separate and analyze physical and chemical processes which are highly overlapped in their EIS data. In order to encourage the application and popularization of DRT deconvolution technology, several core questions are addressed in this paper: (1) DRT deconvolution principle, implementation steps and important …

Wildfires Force Thousands To Evacuate Near Los Angeles: Here’S How The 2020 Western Fire Season Got So Extreme, Mojtaba Sadegh, Ata Akbari Asanjan, Mohammad Reza Alizadeh

Civil Engineering Faculty Publications and Presentations

Two wildfires erupted on the outskirts of cities near Los Angeles, forcing more than 100,000 people to evacuate their homes Monday as powerful Santa Ana winds swept the flames through dry grasses and brush. With strong winds and extremely low humidity, large parts of California were under red flag warnings.

High fire risk days have been common this year as the 2020 wildfire season shatters records across the West.

More than 4 million acres have burned in California – 4% of the state’s land area and more than double the previous annual record. Five of the state’s six largest historical …

The Year The West Was Burning: How The 2020 Wildfire Season Got So Extreme, Mojtaba Sadegh, Ata Akbari Asanjan, Mohammad Reza Alizadeh

Civil Engineering Faculty Publications and Presentations

More than 4 million acres of California went up in flames in 2020 – about 4% of the state’s land area and more than double its previous wildfire record. Five of the state’s six largest fires on record were burning this year.

In Colorado, the Pine Gulch fire broke the record for that state’s largest wildfire, only to be surpassed by two larger blazes, the Cameron Peak and East Troublesome fires.

Oregon saw one of the most destructive fire seasons in its recorded history, with more than 4,000 homes destroyed.

What caused the 2020 fire season to become so extreme?

Characterization Of Slip Activity In The Presence Of Slip Bands Using Surface-Based Microscopy Techniques, Ryan Aaron Sperry

Theses and Dissertations

Further understanding of mesoscale slip mechanics is crucial to future development of polycrystalline metals with improved performance. The research contained within this thesis aims to characterize localized mesoscale slip on slip bands further through two studies. First, a comprehensive comparison of slip system identification techniques was carried out to further validate each method as well as compare advantages and disadvantages of each. Second, slip bands in the presence of grain boundaries were studied to better characterize the dislocation content and behavior. In the first study, the use of SEM-DIC, AFM, ECCI, and HR-EBSD to characterize slip-system activity was assessed on …

Plasmon-Induced Color And Photochemistry, Paul J. Gieri

Nanoscience and Microsystems ETDs

In recent decades, metallic nanostructures have been extensively studied for a variety of applications due to the ability to support surface plasmons. These excitations, which consist of collective resonant oscillations of the conduction electrons, couple strongly to visible light, confining it into subwavelength volumes. In the first part of this work, we study the optical response of metallic nanostructures supported by metallic substrates. We demonstrate that these systems support a charge transfer plasmon mode, whose frequency is primarily determined by the geometry of the contact area between the nanoparticle and the substrate. In the following part, we exploit this knowledge …

Temporally Multiplexed Ladar Polarimeter, Christian Keyser, Richard Kenneth Martin

AFIT Patents

In a polarimeter, a polarization modulator changes a polarization phase of an output optical pulse with a modulation function that varies in time over the duration of the optical pulse. A static polarization state analyzer, which includes a one or more static polarization component analyzers and detectors, receives the modulated optical pulse after interaction with a target medium and provides time varying intensities of the polarization components of the received pulse. A signal processing module determines a polarization property of the target medium, such as a Mueller matrix, dependent upon time varied intensities over the duration of the received optical …

Developing A Competency Model For Highway Safety Engineers: A Delphi Method, Garrett K. Wheat

LSU Doctoral Dissertations

The primary purpose of this study was to determine the core competencies needed by State DOT Highway Safety Engineers as perceived by Highway Safety experts in the United States. First, a list of competencies was identified. Next, a panel of Highway Safety experts determined the importance of each identified competency for the current year (2020) and for the future (year 2030). Finally, ratings provided by the panel were tested for the presence of consensus.

For this study, the researcher used a Delphi Method as classified by Delbecq, Van de Ven, and Gaustafson (1975). Through this method, a panel of forward-thinking …

In Vitro Study Of Biodegradation Of Glass And Glass Crystals Of The R2o-Ro-Caf2-P2o5-Al2o3-Sio2 System, Aripova Mastura, Mkrtchyan Ripsime

CHEMISTRY AND CHEMICAL ENGINEERING

For bioactive glasses and glass crystals, biodegradation is the most important parameter. The biodegradation process was studied for glasses and glass crystals synthesized in the R2O-RO-CaF2-P2O5-Al2O3-SiO2 system. Degradation analysis of samples was carried out on a Hitachi 902 biochemical analyzer in 0.9% NaCl, 3.8% sodium citrate solution and human serum. . The kinetics of leaching in various environments, the influence of the components of glasses and glass crystals on their biodegradation have been determined. The composition of glass that is most susceptible to degradation has been determined. IR spectroscopic analysis of glasses and crystallized glasses in vitro showed that all …

Configuration And Competitive Reactivity Of Ligands In Mixed Ligand Complexes Of Dialkylditiophosphates And Aminobenbenzimidazole (Part 2. Zn, Fe, Ni), Esbergenova Botakoz, Daminova Shakhlo, Kadirova Zuhra, Sharipov Khasan

CHEMISTRY AND CHEMICAL ENGINEERING

With the aim of determination of electronic and geometrical structures of mixed-ligand complexes, theoretical modeling of the structures of coordination compounds of transition metals with dialkyldithiophosphate chelating ligands with aminobenzimidazoles carried out using quantum chemical methods. Using BIOVIA Materials Accelrys Studio 2017 software packages, the geometry, electron density distribution, and frontier orbitals calculated for the mixed ligand complexes Zn(II), Cu(II), Ni(II), Fe(III), which is necessary for understanding the electronic structure of coordination compounds with chelating ligands.

Designing A Week-Long Biomedical Engineering Summer Camp To Increase Young Students’ Interest And Self-Efficacy In Stem, Kayla Ney

Honors Program: Senior Projects (Public)

In order to combat the negative feelings many young students have towards STEM, I designed a week-long summer camp that teaches students about biomedical engineering as well as collaboration, communication, and confidence with STEM subjects. This work includes a literature review outlining what STEM is and current issues in STEM education, including disinterest in STEM and attrition in STEM degree programs. The literature review outlines current methods and ideas being utilized to combat these issues, namely, inclusive pedagogical strategies, and how some of these concepts can be applied to the summer camp. The curriculum document included outlines each activity, its …

Mechanisms Of Asymmetric Membrane Formation In Nonsolvent-Induced Phase Separation, Jan Ulric Garcia, Tatsuhiro Iwama, Eva Y. Chan, Douglas R. Tree, Kris T. Delaney, Glenn H. Fredrickson

Faculty Publications

We report the first simulations of nonsolvent-induced phase separation (NIPS) that predict membrane microstructures with graded asymmetric pore size distribution. In NIPS, a polymer solution film is immersed in a nonsolvent bath, enriching the film in nonsolvent, and leading to phase separation that forms a solid polymer-rich membrane matrix and polymer-poor membrane pores. We demonstrate how mass-transfer-induced spinodal decomposition, thermal fluctuations, and glass-transition dynamics—implemented with mobility contrast between the polymer-rich and polymer-poor phases—are essential to the formation of asymmetric membrane microstructures. Specifically, we show that the competition between the propagation of the phase-separation and glass-transition fronts determines the degree of …

Development Of Metallic Nuclear Material Purification Process Via Simultaneous Chlorination And Volatilization, Parker Okabe, Devin Rappleye, Matthew Newton, Michael F. Simpson

Faculty Publications

A purification process involving simultaneous chlorination and volatilization is reported using aluminum, iron, gallium, and uranium separation from cerium metal as the demonstration system. Anhydrous Cl₂ gas was reacted with the metal after it had been converted to small particles of hydride at temperatures ranging from 523 to 973 K. Each of the impurities should form chlorides with relatively high saturated vapor pressures. The objective of the process was to volatilize these chlorides after first achieving near-complete conversion of the metals to hydride and then chlorides. Complete conversion of hydrides to chlorides could not be achieved using …

Flexural Behaviour Of Over-Reinforced Concrete Beam Using External Steel Plate, Shatha Sahib Kareem

Student Works (2020-2029)

Over-reinforced concrete beam fails by crushing of the concrete compression zone before the yielding of steel reinforcement in the tension zone. An over-reinforced concrete beam may failed suddenly without warning before failure as the failure is instantaneous. Therefore, numerous codes of practices recommended a beam design to avoid brittle failure. However, in some situations, due to the limitation of spaces, using over-reinforced concrete beam is not avoidable. Previous researches showed that it is possible to design an over-reinforced concrete beam without brittle failure using the methods such as helical-reinforcement, short-stirrups, and hybrid-system. This study is an effort to investigate the …

The Pca-Logistic Method For Identification Of Water Burst In Nalinhe No.2 Coal Mine, Ji Zhuochen, Ding Xiang, Hou Enke, Pu Zhiguo, Xie Peng

Coal Geology & Exploration

Nalinhe No.2 coal mine is the first pair of large-scale mines in the Nalinhe mining area. The water inrush events occur from time to time due to its own complex hydrogeological conditions and strong disturbance of excavation in the initial stage of production, which has caused serious threat to the mining activity safety. Finding the source of gushing water quickly and effectively is the key to control the mine water disaster. Based on the water quality analysis of main aquifers and goaf water samples in Nalinhe No.2 coal mine, and drawing the piper trilinear nomograph water samples, the hydrogeochemical characteristics …