Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Discipline
Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 20971 - 21000 of 198032

Full-Text Articles in Engineering

A Novel And Enhanced Calibration Of The Tilting Weir As A Flow Measurement Structure, Joseph E. Pugh, S. Karan Venayagamoorthy, Timothy K. Gates, Céline Berni, Marie Rastello Mar 2024

A Novel And Enhanced Calibration Of The Tilting Weir As A Flow Measurement Structure, Joseph E. Pugh, S. Karan Venayagamoorthy, Timothy K. Gates, Céline Berni, Marie Rastello

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A large collection of laboratory measurements of piezometric head (h) and discharge (Q) were made over hydraulic models of a tilting weir at nine different angles, ranging from 25.7° to 90° within a 0.3-m-wide flume. These measurements were corroborated with additional laboratory data taken within a 1-m-wide flume across four inclination angles. The range of both inclination angle (θ) and flow scale examined in this study elucidate the nature of the head-discharge rating equation beyond previous work. Results show that as θ decreases under a constant Q, the h over the weir decreases in a monotonic fashion due to the …

Go to article

Methodology To Design Eco-Friendly Fiber-Reinforced Concrete For 3d Printing, Haodao Li, Alfred Addai-Nimoh, Eric Kreiger, Kamal H. Khayat Mar 2024

Methodology To Design Eco-Friendly Fiber-Reinforced Concrete For 3d Printing, Haodao Li, Alfred Addai-Nimoh, Eric Kreiger, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Greater use of locally available supplementary cementitious materials (SCM) to reduce cement content and addition of fiber reinforcement can enhance the performance of 3D printing (3DP) technology in construction. In this study, three classes of eco-friendly 3D printable fiber-reinforced mixtures were targeted, namely ultra-high-performance concrete (UHPC), high-performance concrete (HPC), and conventional concrete (CC). A step-by-step methodology was proposed to maximize the substitution rate of cement with SCM and limestone filler and optimize fiber volume for the successful development of 3D printable fiber-reinforced materials. Binder combinations were initially investigated on the paste level to determine the packing density and robustness. Selected …

Go to article

Circular Economy Policies For Decarbonization Of Us Commercial Building Stocks: Data Integration And System Dynamics Coflow Modeling Approach, Radwa Eissa, Islam H. El-Adaway Mar 2024

Circular Economy Policies For Decarbonization Of Us Commercial Building Stocks: Data Integration And System Dynamics Coflow Modeling Approach, Radwa Eissa, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Despite the recognition of the built environment as a sector with high potential for reducing embodied emissions, there is a lack of national-level data on embodied carbon emissions attributed to the US commercial building stocks. Hence, there is a need to benchmark the current state of embodied emissions attributed to the commercial built environment and the impact of circular economy (CE) policies for their decarbonization to facilitate well-informed decision-making. This paper fills this knowledge gap through providing policy makers with a framework that estimates the current and future projections of embodied carbon emissions attributable to the US commercial building stocks …

Go to article

Natural Gas Induced Vegetation Stress Identification And Discrimination From Hyperspectral Imaging For Pipeline Leakage Detection, Pengfei Ma, Ying Zhuo, Genda Chen, Joel G. Burken Mar 2024

Natural Gas Induced Vegetation Stress Identification And Discrimination From Hyperspectral Imaging For Pipeline Leakage Detection, Pengfei Ma, Ying Zhuo, Genda Chen, Joel G. Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Remote Sensing Detection of Natural Gas Leaks Remains Challenging When using Ground Vegetation Stress to Detect Underground Pipeline Leaks. Other Natural Stressors May Co-Present and Complicate Gas Leak Detection. This Study Explores the Feasibility of Identifying and Distinguishing Gas-Induced Stress from Other Natural Stresses by Analyzing the Hyperspectral Reflectance of Vegetation. the Effectiveness of This Discrimination is Assessed Across Three Distinct Spectral Ranges (VNIR, SWIR, and Full Spectra). Greenhouse Experiments Subjected Three Plant Species to Controlled Environmental Stressors, Including Gas Leakage, Salinity Impact, Heavy-Metal Contamination, and Drought Exposure. Spectral Curves Obtained from the Experiments Underwent Preprocessing Techniques Such as Standard …

Go to article

Dynamic Model Of Ac-Ac Dual Active Bridge Converter Using The Extended Generalized Average Modeling Framework, Kartikeya Jayadurga Prasad Veeramraju, Jonathan W. Kimball Mar 2024

Dynamic Model Of Ac-Ac Dual Active Bridge Converter Using The Extended Generalized Average Modeling Framework, Kartikeya Jayadurga Prasad Veeramraju, Jonathan W. Kimball

Electrical and Computer Engineering Faculty Research & Creative Works

The ac-ac dual active bridge (DAB) converter is an advanced bidirectional two-port grid interface converter that facilitates active and reactive power flow control between two grids without a dc-link capacitor. This article presents a novel modeling approach for the ac-ac DAB converter using the extended generalized average modeling (EGAM) technique. Unlike the conventional generalized average modeling (GAM) framework, the ac-ac DAB converter's dynamic state variables, including the leakage inductor current and ac grid side LC filters, exhibit grid and switching frequency components, making the standard GAM framework unsuitable for dynamic modeling involving two distinct excitation frequencies. Furthermore, the 2-D GAM …

Go to article

An Impedance-Source-Based Soft-Switched High Step-Up Dc-Dc Converter With An Active Clamp, Saeed Habibi, Ramin Rahimi, Mehdi Ferdowsi, Pourya Shamsi Mar 2024

An Impedance-Source-Based Soft-Switched High Step-Up Dc-Dc Converter With An Active Clamp, Saeed Habibi, Ramin Rahimi, Mehdi Ferdowsi, Pourya Shamsi

Electrical and Computer Engineering Faculty Research & Creative Works

This article proposes a high step-up dc-dc converter based on a trans-inverse impedance-source structure, in which the voltage gain of the converter is increased by using a lower number of turns ratio of the coupled inductors (CI) windings. The proposed converter achieves a very high voltage gain and a very low voltage stress on the switches. An active clamp is incorporated into the topology of the proposed converter, helping to absorb the energy of the leakage inductances of the CI, and to recycle that energy to the output of the converter to further increase the voltage gain. Furthermore, the active …

Go to article

Impact Of The New Context Functional Classifications For Kytc, Arlen Sandlin, Jill Asher, Nikiforos Stamatiadis, Jeff Jasper, Rachel Catchings, Chris Van Dyke Mar 2024

Impact Of The New Context Functional Classifications For Kytc, Arlen Sandlin, Jill Asher, Nikiforos Stamatiadis, Jeff Jasper, Rachel Catchings, Chris Van Dyke

Kentucky Transportation Center Research Report

State transportation agencies are adopting an expanded context classification system to inform project development and delivery. This system classifies roadways into one of five categories based on factors such as level of development, building densities and setbacks, multimodal user patterns and requirements, network permeability, and speed. Compared to functional classification, context classification better captures the types of mobility, travel patterns, and user mixes observed in specific contexts. The expanded context classification system is found in AASHTO’s A Policy on Geometric Design of Highways and Streets (7th Edition). The forthcoming 8th edition will deepen integration of context classification throughout …

Go to article

Pl 43 Traffic Forecasting Report 2023, Mei Chen, Xu Zhang, Eugene Antwi Mar 2024

Pl 43 Traffic Forecasting Report 2023, Mei Chen, Xu Zhang, Eugene Antwi

Kentucky Transportation Center Research Report

This document is the seventh edition of the Traffic Forecasting Report (TFR) for the state of Kentucky. TFR data are important for multiple engineering applications that involve analyzing temporal and spatial variability in traffic distributions and volumes. Most of the metrics discussed in the report were computed using data from 2019, 2021, and 2022 — excluded from consideration were 2020 data because they exhibited anomalous traffic patterns tied to shutdowns associated with the COVID-19 pandemic. Data summarized in this report include average daily traffic, annual average daily truck traffic, travel activity by vehicle type, weekday and weekend hourly volume percentages, …

Go to article

Multilayered Energy Management Framework For Extreme Fast Charging Stations Considering Demand Charges, Battery Degradation, And Forecast Uncertainties, Waqas Ur Rehman, Jonathan W. Kimball, Rui Bo Mar 2024

Multilayered Energy Management Framework For Extreme Fast Charging Stations Considering Demand Charges, Battery Degradation, And Forecast Uncertainties, Waqas Ur Rehman, Jonathan W. Kimball, Rui Bo

Electrical and Computer Engineering Faculty Research & Creative Works

To achieve a cost-effective and expeditious charging experience for extreme fast charging station (XFCS) owners and electric vehicle (EV) users, the optimal operation of XFCS is crucial. It is, however, challenging to simultaneously manage the profit from energy arbitrage, the cost of demand charges, and the degradation of a battery energy storage system (BESS) under uncertainties. This article, therefore, proposes a multilayered Mult timescale energy flow management framework for an XFCS by considering long- and short-term forecast uncertainties, monthly demand charges reduction, and BESS life degradation. in the proposed approach, an upper scheduling layer (USL) ensures the overall operation economy …

Go to article

Modeling And Understanding Dispute Causation In The Us Public-Private Partnership Projects, Mohamad Abdul Nabi, Rayan H. Assaad, Islam H. El-Adaway Mar 2024

Modeling And Understanding Dispute Causation In The Us Public-Private Partnership Projects, Mohamad Abdul Nabi, Rayan H. Assaad, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The partnership between the public and private sectors has led to a new and innovative way of delivering infrastructure projects that is referred to as public-private partnership (PPP). There are various benefits associated with PPP delivery methods including risk sharing, access to private funding, innovation, and flexibility, among others. Despite the proved benefits, contract conflicts and disputes are very common in PPP projects. While previous research studies examined the risks and the potential causes of conflicts in PPP projects, little-to-no research efforts were directed to study and model the interconnectivities between the different causes of conflicts in PPP agreements. To …

Go to article

Comprehensive Numerical Modeling Of Prestressed Girder Bridges Under Low-Velocity Impact, Mohamed T. Elshazli, Mohanad M. Abdulazeez, Mohamed Elgawady, Ahmed Ibrahim Mar 2024

Comprehensive Numerical Modeling Of Prestressed Girder Bridges Under Low-Velocity Impact, Mohamed T. Elshazli, Mohanad M. Abdulazeez, Mohamed Elgawady, Ahmed Ibrahim

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Accidental Collisions Involving Over-Height Trucks That Exceed Vertical Clearance Limits And Bridge Superstructures Frequently Happen, Resulting In Compromised Girders And Potential Threats To Structural Safety And Performance. The Numerical Simulation Of Large-Scale Prestressed Girder Bridge Collisions Poses Challenges Due To The Associated Nonlinearities, As Well As The Limited Availability Of Large-Scale Experimental Testing Data In The Literature Due To Cost And Complexity Constraints. This Study Introduces A Numerical Modeling Approach To Efficiently Capture The Response Of Prestressed Girder Bridges Under Lateral Impact Loads. A Finite Element (FE) Model Was Developed Using LS-DYNA And Meticulously Validated Against Experimental Data From The …

Go to article

Infrared Investigation In Singapore (Iris) Observatory: Urban Heat Island Contributors And Mitigators Analysis Using Neighborhood-Scale Thermal Imaging, Clayton Miller, Vasantha Ramani, Clayton Miller Mar 2024

Infrared Investigation In Singapore (Iris) Observatory: Urban Heat Island Contributors And Mitigators Analysis Using Neighborhood-Scale Thermal Imaging, Clayton Miller, Vasantha Ramani, Clayton Miller

Research Collection College of Integrative Studies

This paper studies heat fluxes from contributors and mitigators of urban heat islands using thermal images and weather data. Thermal images were collected by a rooftop observatory between November 2021 and April 2022. Over the same period, weather stations were operating at several locations on a university campus in Singapore. From collected data, a method was defined to estimate sensible and latent heat fluxes from building façades, vegetation, and traffic. Before analyzing heat fluxes using the method, thermal images were calibrated against measurements made with contact surface sensors. Results show that the method can be used to study heat fluxes …

Go to article

Applications Of Plastics In The Automotive Industry: Current Trends And Future Perspectives, Hossein Abedsoltan Mar 2024

Applications Of Plastics In The Automotive Industry: Current Trends And Future Perspectives, Hossein Abedsoltan

Chemical and Biochemical Engineering Faculty Research & Creative Works

Plastics have transformed the automotive industry, contributing substantially to automobile design, weight reduction, fuel efficiency, safety, and sustainability. This review paper examines the applications of plastics in the automotive sector, evaluates the present trends, and describes the future plastic consumption possibilities, emphasizing emerging technology and sustainable practices. The paper delineates how plastics have become an essential component of automotive innovation and illustrates the possibilities for additional breakthroughs in this dynamic industry. Highlights: Advances in plastics, bioplastics, and smart materials in the auto industry. Plastic role in design, safety, and sustainability in the auto industry. Recycling and the circular economy of …

Go to article

Distributed Solar Generation: Current Knowledge And Future Trends, Gasser G. Ali, Islam H. El-Adaway Mar 2024

Distributed Solar Generation: Current Knowledge And Future Trends, Gasser G. Ali, Islam H. El-Adaway

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Distributed solar generation (DSG) has been growing over the previous years because of its numerous advantages of being sustainable, flexible, reliable, and increasingly affordable. DSG is a broad and multidisciplinary research field because it relates to various fields in engineering, social sciences, economics, public policy, and others. Developing a holistic understanding of the state of research related to DSG can be difficult. Motivated to provide that understanding, the goal of this paper is to explore current and emerging multidisciplinary research trends associated with DSG. To achieve that, (1) a large data set of approximately 66,000 publications was collected; (2) the …

Go to article

Designing Explainable Ai To Improve Human-Ai Team Performance: A Medical Stakeholder-Driven Scoping Review, Harishankar V. Subramanian, Casey I. Canfield, Daniel Burton Shank Mar 2024

Designing Explainable Ai To Improve Human-Ai Team Performance: A Medical Stakeholder-Driven Scoping Review, Harishankar V. Subramanian, Casey I. Canfield, Daniel Burton Shank

Engineering Management and Systems Engineering Faculty Research & Creative Works

The rise of complex AI systems in healthcare and other sectors has led to a growing area of research called Explainable AI (XAI) designed to increase transparency. In this area, quantitative and qualitative studies focus on improving user trust and task performance by providing system- and prediction-level XAI features. We analyze stakeholder engagement events (interviews and workshops) on the use of AI for kidney transplantation. From this we identify themes which we use to frame a scoping literature review on current XAI features. The stakeholder engagement process lasted over nine months covering three stakeholder group's workflows, determining where AI could …

Go to article

Understanding The Impact Of Trade Policy Effect Uncertainty On Firm-Level Innovation Investment: A Deep Learning Approach, Daniel Chang, Nan Hu, Peng Liang, Morgan Swink Mar 2024

Understanding The Impact Of Trade Policy Effect Uncertainty On Firm-Level Innovation Investment: A Deep Learning Approach, Daniel Chang, Nan Hu, Peng Liang, Morgan Swink

Research Collection School Of Computing and Information Systems

Integrating the real options perspective and resource dependence theory, this study examines how firms adjust their innovation investments to trade policy effect uncertainty (TPEU), a less studied type of firm specific, perceived environmental uncertainty in which managers have difficulty predicting how potential policy changes will affect business operations. To develop a text-based, context-dependent, time-varying measure of firm-level perceived TPEU, we apply Bidirectional Encoder Representations from Transformers (BERT), a state-of-the-art deep learning approach. We apply BERT to analyze the texts of mandatory Management Discussion and Analysis (MD&A) sections of annual reports for a sample of 22,669 firm-year observations from 3,181 unique …

Go to article

Multiobjective Stochastic Optimization: A Case Of Real-Time Matching In Ride-Sourcing Markets, Guodong Lyu, Wang Chi Cheung, Chung-Piaw Teo, Hai Wang Mar 2024

Multiobjective Stochastic Optimization: A Case Of Real-Time Matching In Ride-Sourcing Markets, Guodong Lyu, Wang Chi Cheung, Chung-Piaw Teo, Hai Wang

Research Collection School Of Computing and Information Systems

Problem Definition: The job of any marketplace is to facilitate the matching of supply with demand in real-time. Success is often measured using various metrics. The challenge is to design matching algorithms to balance the trade-offs among multiple objectives in a stochastic environment, to arrive at a “compromise” solution, which minimizes say the ℓp-norm-based distance function (for some 1 ≤p ≤∞) between the attained performance metrics and the target performances.Methodology/Results: We observe that the sample-average-approximation formulation of this multi-objective stochastic optimization problem can be solved by an online algorithm that uses only gradient information from “historical” (i.e., past) sample information, …

Go to article

Wavelength-Induced Shedding Frequency Modulation Of Seal Whisker Inspired Cylinders, Trevor Dunt, Kirby S. Heck, Kathleen Lyons, Christin Murphy, Raul Bayoan Cal, Jennifer A. Franck Mar 2024

Wavelength-Induced Shedding Frequency Modulation Of Seal Whisker Inspired Cylinders, Trevor Dunt, Kirby S. Heck, Kathleen Lyons, Christin Murphy, Raul Bayoan Cal, Jennifer A. Franck

Mechanical and Materials Engineering Faculty Publications and Presentations

The spanwise undulated cylinder geometry inspired by seal whiskers has been shown to alter shedding frequency and reduce fluid forces significantly compared to smooth cylindrical geometry. Undulation wavelength is systematically investigated in order to explore its effect on unsteady lift force and shedding frequency. Prior research has parameterized the whisker-inspired geometry and demonstrated the relevance of geometric variations on force reduction properties. Among the geometric parameters, undulation wavelength was identified as a significant contributor to forcing changes. To analyze the effect of undulation wavelength, a thorough investigation isolating changes in wavelength is performed to expand upon previous research that parameterized …

Go to article

Experimental Investigation Of Long-Term Performance Of Fiber-Reinforced Epoxy And Polyurethane Polymer Composites, Abdel Hamid I. Mourad, Amir Hussain Idrisi, Asima Zahoor, Muhammad M. Sherif, Beckry M. Abdel-Magid Mar 2024

Experimental Investigation Of Long-Term Performance Of Fiber-Reinforced Epoxy And Polyurethane Polymer Composites, Abdel Hamid I. Mourad, Amir Hussain Idrisi, Asima Zahoor, Muhammad M. Sherif, Beckry M. Abdel-Magid

Michigan Tech Publications

The primary challenge encountered by polymers and their composites when exposed to saline water is their inadequate ability to withstand wear and tear over time. With a potential to replace conventional materials the long-term performance of FRP composites is still a novice area. This manuscript thus, reports an experimental investigation and prediction of the durability of fiber-reinforced polymer composites exposed to seawater at different temperatures. E-glass/epoxy and E-glass/polyurethane samples were exposed to 23 °C, 45 °C and 65 °C seawater for up to 2700 days (90 months). Tensile tests evaluated the mechanical performance of the composite as a function of …

Go to article

Pa2blo: Low-Power, Personalized Audio Badge, Hemanth Sabbella, Dulaj Sanjaya Weerakoon, Manoj Gulati, Archan Misra Mar 2024

Pa2blo: Low-Power, Personalized Audio Badge, Hemanth Sabbella, Dulaj Sanjaya Weerakoon, Manoj Gulati, Archan Misra

Research Collection School Of Computing and Information Systems

We present the hardware design and software pipeline for an ultra-low power device, in the form factor of a wearable badge, that supports energy efficient sensing, processing and wireless transfer of human voice commands and interactions. The proposed system, called PA2BLO, is envisioned to support both: (a) real-time, scalable, authorized voice based interaction and control of devices and appliances, and (b) longitudinal, low-power logging of natural voice interactions. PA2BLO in-troduces two key novel capabilities. First, it includes a low power, low-complexity voice authentication module that is able to reliably authenticate an authorized user only using low sampling rate (500 Hz) …

Go to article

Preliminary Structure Design And Analysis Of A 27u Cubesat Chassis, Matthew Evans Mar 2024

Preliminary Structure Design And Analysis Of A 27u Cubesat Chassis, Matthew Evans

Theses and Dissertations

The Air Force Institute of Technology (AFIT) has renewed its interest in the area of CubeSat research by performing the preliminary structural design and analysis of a 27U CubeSat. The aim of this research is to shed light on the design process for this CubeSat and highlight design challenges and assumptions. Next, to provide the testing standards as outlined by the NASA General Environmental Verification Standards (GEVS) and present a modal analysis in various configurations of 27U CubeSat using Finite Element Analysis (FEA). The 27U CubeSat was manufactured by machining plates made from aluminum alloy 7075-T6, and validated individual component …

Go to article

Erosion Wear Characterisation Of An Open Ductile Iron Butterfly Valve Subjected To Aluminium Oxide Particle Slurry Flow, Prashan Perera, Kevin Hayward, Ferdinando Guzzomi, Ana Vafadar Mar 2024

Erosion Wear Characterisation Of An Open Ductile Iron Butterfly Valve Subjected To Aluminium Oxide Particle Slurry Flow, Prashan Perera, Kevin Hayward, Ferdinando Guzzomi, Ana Vafadar

Research outputs 2022 to 2026

This study attempts to identify the most erosion-sensitive valve locations due to aluminium oxide particle impingement under various pressure drops and valve closing angles, utilising the Ansys discrete phase model (DPM). Additionally, this research explores the feasibility of integrating laser scanning technology into the fields of tribology and particle erosion analysis. The results indicate higher erosion damage on the top valve surface due to the direct effects of particle velocity and impingement angles compared to the underside of the valve, where particle trajectories are highly affected by turbulence. Moreover, smaller closing angles proved to be detrimental to valve service life, …

Go to article

Wave Overtopping Layer Thickness On The Crest Of Rubble Mound Seawalls, Ali Koosheh, Amir Etemad-Shahidi, Nick Cartwright, Rodger Tomlinson, Marcel R. A. Van Gent Mar 2024

Wave Overtopping Layer Thickness On The Crest Of Rubble Mound Seawalls, Ali Koosheh, Amir Etemad-Shahidi, Nick Cartwright, Rodger Tomlinson, Marcel R. A. Van Gent

Research outputs 2022 to 2026

During storms, ensuring the protection of people, vehicles and infrastructure on the crest of coastal structures from wave overtopping hazards is crucial. The thickness of the wave overtopping layer is a key variable used for assessing safety and maintaining a secure design. Traditionally, this parameter is associated with the height difference between the fictitious wave run-up level exceeded by 2% of waves and the crest freeboard of coastal structures. This study aims to investigate the wave overtopping layer thickness on the crest of rubble mound seawalls. To achieve this, a series of 125 small-scale 2D physical model tests were conducted …

Go to article

Effect Of Heavy-Duty Electric Vehicles On Tire–Pavement Contact Forces, Jaime Hernandez, Angeli Jayme, Johann J. Cardenas Huaman, Imad L. Al-Qadi Mar 2024

Effect Of Heavy-Duty Electric Vehicles On Tire–Pavement Contact Forces, Jaime Hernandez, Angeli Jayme, Johann J. Cardenas Huaman, Imad L. Al-Qadi

Civil and Environmental Engineering Faculty Research and Publications

Electric vehicles offer higher acceleration than conventional internal combustion engines due to larger engine torque. The design and placement of battery packs in heavy-duty electric vehicles are still being optimized, as they can affect axle load distributions and consequently impact pavement analysis and design. This study presents a finite element model of a dual tire assembly considering varying load and acceleration conditions to investigate the effect of conventional and electric heavy-duty vehicles on tire–pavement contact forces. Three scenarios for battery pack locations were examined, leading to six loading conditions for both internal combustion engines and electric trucks. The resulting 3D …

Go to article

Small Unmanned Aircraft System Detection And Tracking With Audio, Computer Vision, And Deep Learning Techniques, Anthony C. Brunson Mar 2024

Small Unmanned Aircraft System Detection And Tracking With Audio, Computer Vision, And Deep Learning Techniques, Anthony C. Brunson

Theses and Dissertations

sUAS present significant risks to local and federal agencies when under the control of negligent, reckless, or criminal operators. In the face of an escalating presence of sUAS in shared airspace with traditional aircraft, and their deployment in protected airspace as potential weapons, safeguarding personnel, facilities, and assets becomes paramount. This research seeks to address this emerging threat by investigating the efficacy of integrating low-cost distributed sensors and Machine learning (ML) models to enhance battlespace awareness and complement existing sensing platforms for real-time sUAS detection, classification, and localization. The thesis introduces the conceptualization and development of a Drone Detection Command …

Go to article

3- And 6-Degree-Of-Freedom Investigation Of Aerobraking To Support Cislunar And Planetary Operations, Erica C. Higginbotham Mar 2024

3- And 6-Degree-Of-Freedom Investigation Of Aerobraking To Support Cislunar And Planetary Operations, Erica C. Higginbotham

Theses and Dissertations

The first aerobraking experiment occurred in 1991 as part of the Hiten spacecraft’s cislunar survey mission, while the first non-Earth aerobraking experiment occurred in 1993 as part of the Magellan spacecraft’s mission to Venus. Although making only two trans-atmospheric passes to reduce its apogee altitude, the success of Hiten’s experiment led to the implementation of aerobraking by Magellan, reducing its orbit from elliptical to nearly circular over a span of 70 Earth days by leveraging aerodynamic drag to reduce its orbital energy via transiting the upper region of Venus’ atmosphere. The Magellan experiment helped prove the viability of aerobraking for …

Go to article

Computational Modeling Of Single Shear Bolted Joints In Hybrid Composite Laminates With And Without Film Adhesive, Cameron S. Mcmahan Mar 2024

Computational Modeling Of Single Shear Bolted Joints In Hybrid Composite Laminates With And Without Film Adhesive, Cameron S. Mcmahan

Theses and Dissertations

This research explores the effectiveness of predicting composite failure subject to quasi-static loading conditions using computational methods. FEA models were created using Abaqus and were employed to predict composite yield and initial failure behavior. Boundary conditions are generated to replicate the loading scenario seen in the experimental tests. Computationally predicted structural response of the composite range in accuracy from a 2% difference compared to experimental values to a maximum of 63%.

Go to article

Trajectory Optimization Via Direct Collocation Methods Of Boost-Glide Vehicle With Newtonian Aerodynamic Model, Andrew Bonavita Mar 2024

Trajectory Optimization Via Direct Collocation Methods Of Boost-Glide Vehicle With Newtonian Aerodynamic Model, Andrew Bonavita

Theses and Dissertations

In this work, a Newtonian aerodynamic model was developed for an elliptic cone glide geometry at a variety of angles of attack, and a functional relationship between an input angle of attack and the vehicle lift and drag coefficients was developed. This model was used in a direct orthogonal collocation framework to simulate a series of boost-glide trajectories, with objectives of minimum distance to target, minimum time to target, and maximum velocity to target. The optimal control problem was then expanded into a reachability study, considering a wide range of additional scenarios, along with studies on the vehicle range capabilities. …

Go to article

Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters, John P. Di Lella Mar 2024

Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters, John P. Di Lella

Theses and Dissertations

The desire for more powerful engines drives higher turbine inlet temperatures and a greater need to cool them. Experimentalists attempt to match cooling effectiveness between two conditions by matching several non-dimensional parameters, one of which is the coolant warming factor. The first investigation of this study examines the effect of the internal Reynolds number and the advective capacity ratio on the coolant warming factor by making use of a computational model and four different gases. It indicates the non-negligible and opposing effects of external convection and solid conduction on the coolant warming factor at matched internal Reynolds number and advective …

Go to article

Optimal Trajectory Solutions For Unmanned Pursuer/Evader Offensive Counterair Including Engagement Zone, Alexander Hansen Mar 2024

Optimal Trajectory Solutions For Unmanned Pursuer/Evader Offensive Counterair Including Engagement Zone, Alexander Hansen

Theses and Dissertations

This work considers a two-actor scenario of a faster, unmanned pursuer with an engagement zone (EZ) and a non-maneuvering mobile evader. The pursuer aims to capture an evader with a circular EZ. The EZ is dynamic and shifts as a function of the evader’s velocity vector. As the evader’s strategy changes, the EZ relative to the pursuer adjusts based on relative heading and speed of the two agents. Using nonlinear optimal control techniques, the optimal trajectory and minimum time to engage the evader are determined for various pursuer initial headings and positions through MATLAB simulation. The results build a control …

Go to article

First Prev Next Last