Engineering Commons^™

Low-Loss, Compact, Spot-Size-Converter Based Vertical Couplers For Photonic Integrated Circuits, Praveen K.J. Singaravelu, G.C.R. Devarapu, Sebastian A. Schulz, Quentin Wilmart, Stéphane Malhouitre, Ségolène Olivier, Liam O’Faolain

Cappa Publications

In recent years, the monolithic integration of new materials such as SiN, Ge and LiNbO3 on silicon (Si) has become important to the Si photonics community due to the possibility of combining the advantages of both material systems. However, efficient coupling between the two different layers is challenging. In this work, we present a spot size converter based on a two-tier taper structure to couple the optical mode adiabatically between Si and SiN. The fabricated devices show a coupling loss as low as 0.058 dB  ±  0.01 dB per transition at 1525 nm. The low coupling loss between the Si …

Evaluation Of Photogrammetry And Inclusion Of Control Points: Significance For Infrastructure Monitoring, Renee Oats, Rudiger Escobar-Wolf, Thomas Oommen

Department of Civil, Environmental, and Geospatial Engineering Publications

Structure from Motion (SfM)/Photogrammetry is a powerful mapping tool in extracting three-dimensional (3D) models from photographs. This method has been applied to a range of applications, including monitoring of infrastructure systems. This technique could potentially become a substitute, or at least a complement, for costlier approaches such as laser scanning for infrastructure monitoring. This study expands on previous investigations, which utilize photogrammetry point cloud data to measure failure mode behavior of a retaining wall model, emphasizing further robust spatial testing. In this study, a comparison of two commonly used photogrammetry software packages was implemented to assess the computing performance of …

An Enhanced Fuel Cell Dynamic Model With Electrochemical Phenomena Parameterization As Test Bed For Control System Analysis, Victor M. Fontalvo, George J. Nelson, Humberto A. Gomez, Marco E. Sanjuan

PRC-Affiliated Research

In this work, a model of a proton exchange membrane fuel cell (PEMFC) is presented. A dynamic performance characterization is performed to assess the cell transient response to input variables. The model used in the simulation considers three different phenomena: mass transfer, thermodynamics, and electrochemistry. The main sources of voltage loss are presented: activation, electrical resistance, and concentration. The model is constructed to avoid the use of fitted parameters, reducing the experimentation required for its validation. Hence, the electrochemical model is parameterized by physical variables, including material properties and geometrical characteristics. The model is demonstrated as a test-bed for PEMFC …

An Enhanced Fuel Cell Dynamic Model With Electrochemical Phenomena Parameterization As Test Bed For Control System Analysis, Victor M. Fontalvo, George J. Nelson, Humberto A. Gomez, Marco E. Sanjuan

PRC-Affiliated Research

In this work, a model of a proton exchange membrane fuel cell (PEMFC) is presented. A dynamic performance characterization is performed to assess the cell transient response to input variables. The model used in the simulation considers three different phenomena: mass transfer, thermodynamics, and electrochemistry. The main sources of voltage loss are presented: activation, electrical resistance, and concentration. The model is constructed to avoid the use of fitted parameters, reducing the experimentation required for its validation. Hence, the electrochemical model is parameterized by physical variables, including material properties and geometrical characteristics. The model is demonstrated as a test-bed for PEMFC …

Usu Researchers Model Effects Of Microgravity On Muscles During Spaceflight | College Of Engineering, Utah State University

College of Engineering News

Researchers at Utah State University are improving the ways we model muscle loss during spaceflight. Using a rotating cell culture device that simulates microgravity, a team of biological engineers tested various materials and methods to develop a protocol that mimics the physical changes seen in atrophying muscle.

An Enhanced Fuel Cell Dynamic Model With Electrochemical Phenomena Parameterization As Test Bed For Control System Analysis, Victor M. Fontalvo, George J. Nelson, Humberto A. Gomez, Marco E. Sanjuan

PRC-Affiliated Research

In this work, a model of a proton exchange membrane fuel cell (PEMFC) is presented. A dynamic performance characterization is performed to assess the cell transient response to input variables. The model used in the simulation considers three different phenomena: mass transfer, thermodynamics, and electrochemistry. The main sources of voltage loss are presented: activation, electrical resistance, and concentration. The model is constructed to avoid the use of fitted parameters, reducing the experimentation required for its validation. Hence, the electrochemical model is parameterized by physical variables, including material properties and geometrical characteristics. The model is demonstrated as a test-bed for PEMFC …

Implementation Of Augmented Reality In Sae Mini Baja, Brady S. Hales

Undergraduate Honors Theses

Engineers often encounter difficulties in connecting digital data with its physical counterpart. This applies to processing and interpreting data as well as effectively communicating design ideas and considerations. Augmented reality has the ability to solve these problems by overlaying digital data on a physical object. This allows engineers to further explore design considerations such as ergonomics as well as communicate data such as, Finite Element Analysis. This communication may be realized in discussing and collaborating with colleagues, as well as to judges in design reviews. Augmented reality is beneficial in these cases and is further explored in this thesis, utilizing …

Seismic Behavior Of Screen Grid Core Insulated Concrete Form Walls, Anwer Sabah Mohammed Mohammed

Dissertations and Theses

The use of the insulated concrete form (ICF) walls in residential buildings has increased over the past few decades. Much research has been conducted to evaluate the lateral strength of these walls by applying monotonic and cyclic loadings. In the current study, full-scale shake table experiments were employed to evaluate the in-plane behavior of four screen grid insulated concrete form (SGICF) walls. The first two wall specimens utilized dry fit insulated form blocks made from recycled expanded polystyrene granules that were bonded together with cement. When stacked, the cavities in the blocks formed a grid of cores that are evenly …

Evaluation Of Strand To Grout Bond In Post-Tensioned Tendons With Corrosion Inhibiting Penetrants, Kurt Kupselaitis

USF Tampa Graduate Theses and Dissertations

Post tensioning bridges is an efficient way of construction where segments of a bridge are strung together using small diameter high strength strands. The steel strands are passed through internal and/or external ducts within the concrete segments, jacked to high levels of stress, anchored using steel wedges, and then filled with a corrosion inhibiting filler. A cementitious material called grout has been widely used for over 50 years as this filler. The Federal Highway Administration design and construction manual provides recommendations in the properly filling techniques to ensure the tendons are full of grout. Despite the level of detail the …

Numerical Investigation Of Inclination On The Thermal Performance Of Porous Fin Heatsink Using Pseudospectral Collocation Method, George Oguntala, Gbeminiyi Sobamowo, Raed Abd-Alhameed, James Noras

Karbala International Journal of Modern Science

Numerical investigation of inclination effect on the thermal performance of a porous fin heat sink is presented. The developed thermal model is solved using pseudo-spectral collocation method (PSCM). Parametric studies are carried out using PSCM, and the thermal characterization of heat sink with the inclined porous fin of rectangular geometry is presented. Results show that heat sink of inclined porous fin exhibits higher thermal performance than heat sink of vertical porous fin operating under the same thermal conditions with the same geometrical configurations. Performance of inclined or tilted fin increases with decrease in length-thickness aspect ratio. However, increase in the …

Analysis Of Dynamic Behaviour Of A Tensioned Carbon Nanotube In Thermal And Pressurized Environments, Ahmed Yinusa, Gbeminiyi Sobamowo

Karbala International Journal of Modern Science

In this paper, the dynamic behaviour of a tensioned single-walled carbon nanotubes (SWCNT) in thermal and pressurized environments is investigated analytically. With the applications of Bernoulli-Euler and thermal elasticity mechanics theories, the governing equation of motion are developed and solved using Laplace and Fourier transforms. The results of the close form solution in this work are in excellent agreements with past results in literature. From the parametric studies, it is established that as the magnitude of the pressure distribution at the surface increases, the deflection associated with the nanotube increases at any mode of vibration. However, a corresponding increase in …

Kinetics Of Liquid-Assisted Densification During Flash Sintering Of Ceramic Nanoparticles, Rachman Chaim

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

The recent liquid film capillary mechanism [1, 2] proposed for the rapid densification during the flash sintering was consistent energetically with the dissipated power during the process. Following this mechanism, melting of contacts with high electric resistance will induce high attractive capillary forces. Wetting of a solid substrate by its own melt is termed homologous wetting with zero wetting (dihedral) angle. Therefore, wetting and spreading of the melt on its own substrate is extremely fast. Here we will show that particle surface softening / melting and the following transient processes associated with it namely local melt wetting and spreading, particle …

Electrochemical Conversion Of Methane To Ethylene In A Solid Oxide Electrolyer, Changli Zhu, Shisheng Hou, Xiuli Hu, Jinhai Lu, Fanglin Chen, Kui Xie

Faculty Publications

Conversion of methane to ethylene with high yield remains a fundamental challenge due to the low ethylene selectivity, severe carbon deposition and instability of catalysts. Here we demonstrate a conceptually different process of in situ electrochemical oxidation of methane to ethylene in a solid oxide electrolyzer under ambient pressure at 850 °C. The porous electrode scaffold with an in situ-grown metal/oxide interface enhances coking resistance and catalyst stability at high temperatures. The highest C2 product selectivity of 81.2% together with the highest C2 product concentration of 16.7% in output gas (12.1% ethylene and 4.6% ethane) is achieved while the methane …

Civil Engineering And Construction News, Georgia Southern University

Civil Engineering & Construction: News & Publications (2011-2022)

• Dr. David W. Scott named Chair, Department of Civil Engineering & Construction

College Of Engineering News, Georgia Southern University

College of Engineering & Computing: News & Publications (2010-2023)

• Dr. David W. Scott named Chair, Department of Civil Engineering & Construction

Adsorption Of Organic Micropollutants Onto Biochar: A Review Of Relevant Kinetics, Mechanisms And Equilibrium, Yiran Tong, Patrick J. Mcnamara, Brooke K. Mayer

Civil and Environmental Engineering Faculty Research and Publications

As an alternative to activated carbon, biochar has been considered for removal of organic micropollutants from water and wastewater via adsorption. This review elaborates on the fundamental basis of adsorption kinetics, mechanisms, and equilibrium with respect to biochar-based adsorption of micropollutants. The objectives include: 1) linking biochar surface properties with adsorption abilities, 2) categorizing the kinetics of adsorption of aqueous-phase organic compounds onto biochar, 3) categorizing the molecular-scale interactions between organic micropollutants and biochar, and 4) reviewing existing quantitative methods for characterizing adsorption equilibrium of organic micropollutants from water onto an adsorbent surface. To fulfill these goals, the relationships among …

Controlling The Oxygen Electrocatalysis On Perovskite And Layered Oxide Thin Films For Solid Oxide Fuel Cell Cathodes, Gene Yang, Wonsang Jung, Sung-Jin Ahn, Dongkyu Lee

Faculty Publications

Achieving the fast oxygen reduction reaction (ORR) kinetics at the cathode of solid oxide fuel cells (SOFCs) is indispensable to enhance the efficiency of SOFCs at intermediate temperatures. Mixed ionic and electronic conducting (MIEC) oxides such as ABO₃ perovskites and Ruddlesden-Popper (RP) oxides (A₂BO₄) have been widely used as promising cathode materials owing to their attractive physicochemical properties. In particular, oxides in forms of thin films and heterostructures have enabled significant enhancement in the ORR activity. Therefore, we aim to give a comprehensive overview on the recent development of thin film cathodes of SOFCs. We …

Synthesis And Characterization Of LaXBa1-XFeYAl1-YO3, Perovskite Oxides, For Co2 To Co Conversion, Hanzhong Shi

USF Tampa Graduate Theses and Dissertations

As the greenhouse gas effect becomes more serious, it is important to find an effective way to reduce carbon dioxide emissions and/or convert it to value-added products. Based on the catalytic requirements, convert CO₂ to CO using perovskite-type oxides which are suitable for reverse water-gas shift chemical looping (RWGS-CL). The resulting carbon monoxide can be subsequently used for chemical energy storage in the form of hydrocarbon-based fuels and chemicals. This research focuses on the synthesis of the La_xBa_1-xFe_yAl_1-yO₃ perovskite-type oxides, which can form oxygen vacancies, or active sites for CO …

Flash Sintering Of Beta-Alumina Solid Electrolytes For Sodium Battery Applications, Gareth Jones, Y. Hu, S. Ghanizadeh, D. Pearmain, S.N. Heavens, J.S. Blackburn, S. Maclachlan

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

The rechargeable sodium batteries, sodium sulphur (NaS) batteries and molten-salt sodium nickel chloride (Na-NiCl₂) are proven commercially available systems, particularly for large-scale energy storage applications and electric vehicle applications respectively. They have attractive properties such as the use of abundant low-cost raw materials, high energy and power density, high faradaic efficiency of charge/discharge, zero self-discharge rate and proven long-term durability. Conventional manufacturing of the core component, the sodium beta”-alumina solid electrolyte, requires a high sintering temperatures, ~ 1600 °C to achieve high density and good ceramic quality, which contributes significantly to battery cost, energy and time consumption in …

Advantages Of The Method Of High-Voltage Consolidation Of Powder Materials, Evgeny Grigoryev, Vladimir Goltsev, Natalya Ermakova, Andrey Osintsev, Aleksandr Plotnikov

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

The main features of high-voltage electropulse consolidation (H-VEC) of powder materials and the unique possibilities of the method caused by them are considered. The electro-thermal processes in the H-VEC at the contacts between the powder particles and in the macroscale of the whole consolidated sample are analyzed. The results of calculations of the dynamics of closure (collapse) of interparticle pores in the consolidated material are presented. The experimental results of high voltage consolidation W-based heavy alloys are discussed and a theoretical analysis of the kinetics of compaction of powder materials is made. The results of investigation of the macro- and …

Functionalized Plasmonic Gold Nanorods On Chip For Circulating Tumor Dna Point Mutation Detection, George Cheng

ENGS 86 Independent Projects (AB Students)

Nanosensors utilizing the phenomenon of localized surface plasmon resonance (LSPR) have been gaining in popularity due to improved sensitivity and wider dynamic range of optical sensors. Liquid biopsy is a minimally invasive method of analyzing disease dynamics and many technologies have been developed for research laboratory settings. However, there remains a need to simplify the workflow and expand these technologies into point-of-care clinical settings. Functionalized gold nanoparticles dispersed on-chip represent a promising solution to this problem and could also be easily multiplexed to detect many different biomarkers on a single-chip. We are focused on the KRAS G12V point mutation of …

An Integrated Approach For Remanufacturing Job Shop Scheduling With Routing Alternatives., Ling Ling Li, Cong Bo Li, Li Li, Ying Tang, Qing Shan Yang

Henry M. Rowan College of Engineering Departmental Research

Remanufacturing is a practice of growing importance due to increasing environmental awareness and regulations. However, the stochastic natures inherent in the remanufacturing processes complicate its scheduling. This paper undertakes the challenge and presents a remanufacturing job shop scheduling approach by integrating alternative routing assignment and machine resource dispatching. A colored timed Petri net is introduced to model the dynamics of remanufacturing process, such as various process routings, uncertain operation times for cores, and machine resource conflicts. With the color attributes in Petri nets, two types of decision points, recovery routing selection and resource dispatching, are introduced and linked with places …

Field Assisted Sintering Of Larger Scaled Ceramic Parts Using Adapted Tool Design And Hybrid Heating, Martin Bram, Moritz Kindelmann, Alexander M. Laptev, Olivier Guillon

Electric Field Enhanced Processing of Advanced Materials II: Complexities and Opportunities

Field Assisted Sintering/Spark Plasma Sintering (FAST/SPS) is a promising technology for the energy efficient sintering of ceramic, composite and metal powders. The combination of direct current heating and applied pressure enables high heating rates, rapid densification and offers the potential to decrease the sintering temperature significantly. FAST/SPS is of special interest for materials, which are difficult to densify by conventional methods like pressure less sintering. To establish this processing technology on industrial scale, fundamental studies are required to better understand the relationship between processing parameters, specific FAST/SPS boundary conditions and resulting material properties. A challenging task – especially for non-conductive …

Methods And Algorithms To Enhance The Security, Increase The Throughput, And Decrease The Synchronization Delay In 5g Networks, Asim Mazin

USF Tampa Graduate Theses and Dissertations

This dissertation presents several novel approaches to enhance security, and increase the throughput, and decrease the delay synchronization in 5G networks.

First, a new physical layer paradigm was proposed for secure key exchange between the legitimate communication parties in the presence of a passive eavesdropper was presented. The proposed method ensures secrecy via pre-equalization and guarantees reliable communications using Low-Density Parity Check (LDPC) codes. One of the main findings of this research is to demonstrate through simulations that the diversity order of the eavesdropper will be zero unless the main and eavesdropping channels are almost correlated, while the probability of …

Studies Of Boundary Layer Transition From Laminar To Turbulent, Elizabeth Spaulding

Honors Program: Senior Projects (Public)

In engineering applications, there is a strong desire to reduce energy losses due to turbulent energy production. However, the theoretical understanding of turbulent and transition flow is still lacking due to the absence of an exact mathematical solution for turbulent flow. In the current project, transition and turbulent behavior in wall-bounded flow is studied, with an emphasis on concepts from boundary layer theory. Organized structures, such as streaks, waves, and vortices, which occur in such flows, are analyzed. Especially for near-wall structures, control strategies for suppressing such structures are discussed. Using mathematical equations which govern fluid flow, models for different …

Wiwear: Wearable Sensing Via Directional Wifi Energy Harvesting, Huy Vu Tran, Archan Misra, Jie Xiong, Rajesh Krishna Balan

Research Collection School Of Computing and Information Systems

Energy harvesting, from a diverse set of modes such as light or motion, has been viewed as the key to developing batteryless sensing devices. In this paper, we develop the nascent idea of harvesting RF energy from WiFi transmissions, applying it to power a prototype wearable device that captures and transmits accelerometer sensor data. Our solution, WiWear, has two key innovations: 1) beamforming WiFi transmissions to significantly boost the energy that a receiver can harvest ~23 meters away, and 2) smart zero-energy, triggering of inertial sensing, that allows intelligent duty-cycled operation of devices whose transient power consumption far exceeds what …

Material And Regenerative Properties Of An Osteon-Mimetic Cortical Bone-Like Scaffold, Danial Barati, Ozan Karaman, Seyedsina Moeinzadeh, Safaa Kader, Esmaiel Jabbari

Faculty Publications

The objective of this work was to fabricate a rigid, resorbable and osteoconductive scaffold by mimicking the hierarchical structure of the cortical bone. Aligned peptide-functionalize nanofiber microsheets were generated with calcium phosphate (CaP) content similar to that of the natural cortical bone. Next, the CaP-rich fibrous microsheets were wrapped around a microneedle to form a laminated microtube mimicking the structure of an osteon. Then, a set of the osteon-mimetic microtubes were assembled around a solid rod and the assembly was annealed to fuse the microtubes and form a shell. Next, an array of circular microholes were drilled on the outer …

Long-Term Trajectories Of Human Civilization, Seth D. Baum, Stuart Armstrong, Timoteus Ekenstedt, Olle Häggström, Robin Hanson, Karin Kuhlemann, Matthijs M. Maas, James D. Miller, Markus Salmela, Anders Sandberg, Kaj Sotala, Phil Torres, Alexey Turchin, Roman V. Yampolskiy

Faculty and Staff Scholarship

Purpose: This paper aims to formalize long-term trajectories of human civilization as a scientific and ethical field of study. The long-term trajectory of human civilization can be defined as the path that human civilization takes during the entire future time period in which human civilization could continue to exist. Design/methodology/approach: This paper focuses on four types of trajectories: status quo trajectories, in which human civilization persists in a state broadly similar to its current state into the distant future; catastrophe trajectories, in which one or more events cause significant harm to human civilization; technological transformation trajectories, in which radical technological …

Exergetic Relationship Between The Thermal Properties Of Direct Contact Membrane Distillation, D. Perdue, L. Chen, L. Schaefer

Publications

Direct contact membrane distillation (DCMD) is a process that has shown promise within the field of desalination due to its less energy intensive methods and widespread applications. DCMD is a thermally driven microfiltration separation process that operates on the principle of vapor–liquid equilibrium conditions where heat and mass transfer occur simultaneously. Fundamentally, DCMD is based on a porous hydrophobic membrane separating the hot solution (feed) from the cold solution (permeate) where desalinated water condenses. The membrane interfacial temperatures determine the vapor pressure difference across the membrane. In this work, a direct simulation Monte Carlo analysis is employed to investigate how …

Å-Indentation For Non-Destructive Elastic Moduli Measurements Of Supported Ultra-Hard Ultra-Thin Films And Nanostructures, Filippo Cellini, Yang Gao, Elisa Riedo

Publications and Research

During conventional nanoindentation measurements, the indentation depths are usually larger than 1–10 nm, which hinders the ability to study ultra-thin films (<10 >nm) and supported atomically thin two-dimensional (2D) materials. Here, we discuss the development of modulated Å-indentation to achieve sub-Å indentations depths during force-indentation measurements while also imaging materials with nanoscale resolution. Modulated nanoindentation (MoNI) was originally invented to measure the radial elasticity of multi-walled nanotubes. w, by using extremely small amplitude oscillations (<<1 Å) at high frequency, and stiff cantilevers, we show how modulated nano/Å-indentation (MoNI/ÅI) enables non-destructive measurements of the contact stiffness and indentation modulus of ultra-thin ultra-stiff films, including CVD diamond films (~1000 GPa stiffness), as well as the transverse modulus of 2D materials. Our analysis demonstrates that in presence of a standard laboratory noise floor, the signal to noise ratio of MoNI/ÅI implemented with a commercial atomic force microscope (AFM) is such that a dynamic range of 80 dB –– achievable with commercial Lock-in amplifiers –– is sufficient to observe superior indentation curves, having indentation depths as small as 0.3 Å, resolution in indentation <0.05 Å, and in normal load <0.5 nN. Being implemented on a standard AFM, this method has the potential for a broad applicability.