Engineering Commons^™

Health Management And Adaptive Control Of Distributed Spacecraft Systems, Tatiana Alejandra Gutierrez Martinez

Doctoral Dissertations and Master's Theses

As the development of challenging missions like on-orbit construction and collaborative inspection that involve multi-spacecraft systems increases, the requirements needed to improve post-failure safety to maintain the mission performance also increases, especially when operating under uncertain conditions. In particular, space missions that involve Distributed Spacecraft Systems (e.g, inspection, repairing, assembling, or deployment of space assets) are susceptible to failures and threats that are detrimental to the overall mission performance. This research applies a distributed Health Management System that uses a bio-inspired mechanism based on the Artificial Immune System coupled with a Support Vector Machine to obtain an optimized health monitoring …

Noise And Propulsive Efficiency Interactions For Rotors And Propellers At Constant Thrust, Riccardo Roiati

Doctoral Dissertations and Master's Theses

In the emerging market of Advanced Air Mobility (AAM), aerospace companies have been designing and prototyping electric and hybrid vehicles to revolutionize travel. These vehicles must have low noise and particulate emissions while also having enough propulsive efficiency to complete the mission. This thesis aims to study the relationship between noise and propulsive efficiency as related to any aircraft equipped with an electric motor and a variable pitch rotor/propeller. The combination of the electric motor with the variable pitch propeller/rotor allows for a decoupled rotational speed and torque generation, meaning that the electric motor can generate the same amount of …

On-Board Artificial Intelligence For Failure Detection And Safe Trajectory Generation, Eduardo Morillo

Doctoral Dissertations and Master's Theses

The use of autonomous flight vehicles has recently increased due to their versatility and capability of carrying out different type of missions in a wide range of flight conditions. Adequate commanded trajectory generation and modification, as well as high-performance trajectory tracking control laws have been an essential focus of researchers given that integration into the National Air Space (NAS) is becoming a primary need. However, the operational safety of these systems can be easily affected if abnormal flight conditions are present, thereby compromising the nominal bounds of design of the system's flight envelop and trajectory following. This thesis focuses on …

Risks Assessment In The Construction Of Infrastructure Projects Using Artificial Neural Networks, Mohamed Nabawy

Civil Engineering

Infrastructure Project (IP) construction in Egypt is saddled with copious risks emanating from the manque of risk knowledge, driving these projects to enigmatic failure concerning construction cost. The paper’s novel contribution is to acquaint with an Infrastructure Neural Risk Model (INRM) approach that colossally spotlights the substantial risk factors confronting Egypt’s IP construction apropos to Probability of Occurrence (POO) and Impact on Cost (IOC). Hundred and fifty-seven risk factors were compiled from the literature under three risk categories and reduced to 10, portraying the critical risk influencing the IP construction costs inconsolably. The paper’s main merits include identifying the puritanical …

The Consumption Of Photovoltaic Energy Based On The Theory Of Practice And Sociotechnical Transitions, Rafael Lopes Carvalhais, Marcelo De Rezende Pinto Prof.

The Qualitative Report

This paper seeks to advance the discussions involving the articulation between the theory of Sociotechnical Transitions and Practice Theory. The text tries to develop this articulation considering that it is possible to find in the literature notes that the Theory of Sociotechnical Transitions is a suitable partner to be articulated with the Theory of Practice. The proposition was tested in empirical research in which we sought to understand how consumption practices change from adopting photovoltaic energy consumption. The research is categorized as qualitative research. The study offers an interpretation of the object from the theoretical lens provided by Social Practice …

High Performance And Low Cost Passivating, Carrier-Selective Contacts For Silicon Photovoltaics, Jannatul Ferdous Mousumi

Electronic Theses and Dissertations, 2020-2023

The world is now focusing on expanding renewable energy sources to reduce the carbon footprint and mitigate climate change. Solar energy is one of the most environment-friendly and fastest-growing renewable energy sources in the present world. While crystalline silicon (c-Si) based devices dominate the global photovoltaics (PV) market with a current share of 95%, it is still challenging to achieve the theoretical efficiency limit of 29.4% with this technology due to a few performance limiting factors. Contact recombination losses are dominant among them which result from the recombination of photo-generated charge carriers due to the presence of defects at the …

Investigation Of The Effect Of Corundum Layer On The Heat Transfer Of Sic Slab, Sri Elsa Fatmi, Donanta Dhaneswara, Muhammad Anis, Ahmad Ashari

Journal of Materials Exploration and Findings

Aluminum is the most widely used metal in industry. Aluminum smelting is one of the important steps that needs to be carried out to produce products made of aluminum metal with good quality. In the process of smelting aluminum there are several problems that occur, one of which is the growth of corundum in Si C refractories which affects the quality of aluminum melt and the durability of Si C refractories. This research was conducted to see the heat transfer in Si C and the effect of the presence of Corundum on heat transfer. This research was carried out by …

Structural Risk-Based Underwater Inspection (Rbui) As A Cost Reduction Of Field’S End Of Production Life, Ivan Fitrian Putra, Johny Wahyuadi Soedarsono, Mirza Mahendra, Yuki Haidir, Faisal Dwiyana Purnawarman, Iwan Sukirna, Widi Hernowo

Journal of Materials Exploration and Findings

Mubadala Petroleum operates offshore platforms in a southern Makassar Straits that needs to be periodically inspected. The cost for the inspection is massive due to the high cost of mobilization and demobilization of vessels including crew and equipment. In response of a new approach to reduce cost, a Risk-Based Underwater Inspection (RBUI) methodology is developed. This RBUI purpose is to reduce the inspection interval of the offshore platform, from every 2 years to a longer period^[1]. There are existing RBUI methodologies, which are already developed and implemented in other companies^[5]. Purpose of this paper is to …

Risk Management Of Carbon Steel Piping In Sweet Environment Multiphase Fluid Production, Triadhi Panthun Tiggor, Rini Riastuti

Journal of Materials Exploration and Findings

As well reserved depleted and limited, it is necessary to lower the capital expenditure so that lifting SZ reservoir be more profitable. This article first contextualizes the effort done to increase the hydrocarbon lifting in a mature field. Despite the importance to sustain the production, and massive studies done to quantify the associate risk, no structured methodology proposed to manage the risk in respect to optimize the production expenditure by selection of carbon steel as alternative for corrosion resistance material piping. Hence, this article proposed a framework to support the decision-making process to operate in safely manner. Real case study …

Dynamic Rbi With Central Difference Method Approach In Calculation Of Uniform Corrosion Rate: A Casestudy On Gas Pipelines, M.Riefqi Dwi Alviansyah, Fernanda Hartoyo, Zahra Nadia Nurullia, Ari Kurniawan

Journal of Materials Exploration and Findings

The oil and gas industry generally uses a piping system to drain fluids. Even though the pipes used have been well designed, the use of pipes as a means of fluid transportation still provides the possibility of failure that can occur at any time, one of which is due to uniform corrosion. The use of standard Risk Based Inspection (RBI) according to the API RBI 581 document has been widely used to anticipate potential failures to pipe components. The use of standard RBI can reduce the risk of failure significantly. Because the standard RBI considers the component risk value to …

The Comparison Of Pipe Thickness Selection Method Using Full Flange Rating And Non-Full Flange Rating Of Cryogenic Services In An Lng Plant Construction, Ari Agustar, Isdaryanto Iskandar, Wahyuaji Narottama Putra

Journal of Materials Exploration and Findings

Significant growth of gas demand as a source of power generation for domestic use and industries, mainly in the developed countries, has forced the effort to secure the gas supplies located thousands of miles away across the sea as an economical way of gas transportation instead of transporting by pipeline. LNG technology was created as the solution. Natural gas is refrigerated below its boiling point (-160^oC to -162^oC), known as cryogenic temperature or cryogenic service. Material of Construction (MOC) selection report showed that 304/304L and 316/316L Stainless Steel pipe could withstand and be suitable for this …

Energy Efficiency Retrofit And Decarbonization Of Old And Historic Buildings In California, Daria Nikolaeva

Master's Projects and Capstones

Buildings are responsible for almost 40% of total global greenhouse gas emissions and the retrofitting of existing buildings is an essential part of solving the problem. About 75% of buildings in Californian were constructed before the first energy-efficiency building code was adopted in 1978. Old buildings are inefficient, responsible for large carbon footprints and must be retrofitted to stay on track with the state's climate targets. However, current policies do not require substantial changes and tend to favor historic preservation over energy efficiency, missing improvement opportunities. Recognizing the significance of carbon intensity, the 2019 California Energy Efficiency Action Plan shifted …

Leveraging Fpga Primitives To Improve Word Reconstruction During Netlist Reverse Engineering, Reilly Mckendrick, Corey Simpson, Brent Nelson, Jeffrey Goeders

Faculty Publications

While attempting to perform hardware trojan detection, or other low-level design analyses, it is often necessary to inspect and understand the gate-level netlist of an implemented hardware design. Unfortunately this process is challenging, as at the physical level, the design does not contain any hierarchy, net names, or word groupings. Previous work has shown how gate-level netlists can be analyzed to restore high-level circuit structures, including reconstructing multi-bit signals, which aids a user in understanding the behavior of the design. In this work we explore improvements to the word reconstruction process, specific to FPGA platforms. We demonstrate how hard-block primitives …

Computational Tools For Modeling And Simulation Of Sooting Turbulent Non-Premixed Flames, Victoria B. Stephens

Theses and Dissertations

Turbulent combustion systems are physically complex processes that involve many interdependent phenomena---including turbulent fluid dynamics, multi-component mass transfer, convective and radiative heat transfer, and multiphase flow---that occur over a wide range of length and time scales. Modeling and simulation studies complement experimental work by implementing and validating models and providing predictive capabilities, but current software tools are often limited by a lack of standardization and best practices, non-robust implementation, or over-specialization. Some topics in combustion CFD research, notably radiative heat transfer and soot modeling, are critically underrepresented in simulation studies as a result of software limitations. This project establishes and …

Cloud Container Security’ Next Move, Vishakha Sadhwani

Dissertations and Theses

In the last few years, it is apparent to cybersecurity experts everywhere that the proverbial container tech genie is out of the bottle, and has been widely embraced across multiple organizations. To achieve the flexibility of building and deploying applications anywhere and everywhere, cloud native environments have gained great momentum and made the development lifecycle simpler than ever. However, container environments brings with them a range of cybersecurity issues that includes images, containers, hosts, runtimes, registries, and orchestration platforms, which needs the necessity to focus on investing in securing your container stack.

According to this report[1], released by cloud-native …

Influence Of Emotional Intelligence And Leadership Behavior In The Construction Industry., Zeeshan Akther Mohammed

Harrisburg University Dissertations and Theses

This thesis explores the relationship between emotional intelligence (EI), work engagement, and project success among mid-level management in the construction industry. Multiple sources, including journals and research papers, were examined to establish the importance of EI and its impact on work engagement. The study aims to provide a comprehensive understanding of EI and its influence on the work engagement of mid-level employees. The findings highlight the correlation between EI and work engagement, quantifying the threshold of EI required for optimal contribution to organizational success. The research questions address the relationship between EI and work engagement in the construction industry, as …

Synthesis And Characterization Of Hybrid Catalysts For Fischer-Tropsch Jet Fuel Production, Jack M. Steinagel

Honors College Theses

Climate change is a major issue that our world is facing today. Finding renewable options for current infrastructure is paramount to solving this issue. Fischer-Tropsch synthesis of syngas from gasified biomass can produce renewable fuels that can be used in current conventional combustion engines. In order to make this process more industrially viable, a higher selectivity towards the desired range of liquid hydrocarbon products must be achieved. A novel way to do this is to introduce a catalyst to the Fischer-Tropsch reaction. The catalyst’s physical and chemical properties can promote chain growth of specific hydrocarbons. For the purpose of this …

Developing An Accurate Simulation Model For Predicting Friction Stir Welding Processes In 2219 Aluminum Alloy, Kennen Brooks

Theses and Dissertations

Modeling of friction stir welding (FSW) is challenging, as there are large gradients in both strain rate and temperature that must be accounted for in the constitutive law of the material being joined. Constitutive laws are most often calibrated using flow stresses from hot compression or hot torsion testing, where strain rates are much lower than those of the FSW process. As such, the current work employed a recently developed method to measure flow stresses in AA 2219-T67 at the high strain rates typical of FSW. These data were used in the development of a finite element simulation of FSW …

Advanced Isogeometric Discretization Techniques, Kyle Dennis Richardson

Theses and Dissertations

In this dissertation, I provide a robust, efficient inverse mapping algorithm for use in immersed simulation methods, specifically in the Flex Representation Method. I also explore a structural theory that unifies the theories of solids, shells, beams, and rigid bodies. As part of this, I preform a preliminary exploration of applying the Flex Representation Method to shells. Finally, I explore why higher order elements suffer from small critical time steps in explicit dynamics. I then propose a simple method of remedying this issue by exploiting the properties of U-splines.

A Comparative Study On Blockchain-Based Electronic Health Record Systems: Performance, Privacy, And Security Between Hyperledger Fabric And Ethereum Frameworks, Md Jobair Hossain Faruk, Hossain Shahriar, Maria Valero, Xia Li

Master of Science in Software Engineering Theses

Traditional data collection, storage, and processing of Electronic Health Records (EHR) utilize centralized techniques that pose several risks of single point of failure and lean the systems to a number of internal and external data breaches that compromise their reliability and availability. Addressing the challenges of conventional database techniques and improving the overall aspects of EHR application, blockchain technology is being evaluated to find a possible solution. Blockchain refers to an emerging distributed technology and incorruptible database of records or digital events which execute, validate, and maintain by a ledger technology to provide an immutable architecture and prevent records manipulation …

Retention Forces For Drops On Microstructured Superhydrophobic Surfaces, Shaur Humayun, R. Daniel Maynes, Julie Crockett, Brian D. Iverson

Faculty Publications

Accurate models of retention forces between drops and superhydrophobic (SH) surfaces are required to predict drop dynamics on the surface. This retention force is, in turn, useful in modeling heat transfer rates for dropwise condensation on a SH surface. Drop contact angle distribution and base area on SH surfaces are essential factors for predicting retention forces. The present work measures the contact angle distribution and base area shapes of various drop sizes over a wide range of solid fraction for inclined microstructured SH surfaces at the point of drop departure. Base area shape was found to be well approximated using …

A Model For Equity-Oriented Prek-12 Engineering, Christine M. Cunningham, Gregory J. Kelly

Journal of Pre-College Engineering Education Research (J-PEER)

In this paper, we address the societally important issue of developing a more equitable approach to preK-12 engineering education. Our primary emphasis is on K-8 grades—a time when first impressions of engineering may be developed. Calls for increased participation by all students, including those who have been historically marginalized, motivate the need for theoretically grounded ways of developing and assessing educational programs. This paper draws from sociocultural learning theory and applies four theoretical and empirical analyses to derive design principles for equity that can inform curriculum, instruction, and assessment of preK-12 engineering education programs. We present a model for equity-oriented …

Data-Driven Estimation Of The Power Grid Inertia With Increased Levels Of Renewable Generation Resources, Che Kai Chang

Theses - ALL

The thesis investigates methods for estimating inertia in systems at different levels of renewable energy penetrations. Estimating renewable generators' inertia is challenging because their structures differ from traditional generators. Moreover, the power generated from renewable energy resources is not stable, depending on weather conditions. When a power grid has a disturbance, photovoltaic inverter control influences a power grid inertia by different controllers, such as power factor and reactive power control, to bring a power grid back to a steady state. The changing reactive power impacts the frequency, which strongly relates to inertia and increases the inertia estimation problem.

Several papers …

The Combined Impact Of Redcedar Encroachment And Climate Change On Water Resources In The Nebraska Sand Hills, Yaser Kishawi, Aaron R. Mittelstet, Zablon Adane, Nawaraj Shrestha, Paolo Nasta

Department of Agricultural and Biological Systems Engineering: Faculty Publications

The Nebraska Sand Hills (NSH) is considered a major recharge zone for the High Plains Aquifer in the central United States. The uncontrolled expansion of the eastern redcedar (Juniperus Virginiana) under climate warming is posing threats to surface water and groundwater resources. The combined impact of land use and climate change on the water balance in the Upper Middle Loup River watershed (4,954 km²) in the NSH was evaluated by simulating different combination of model scenarios using the Soil Water Assessment Tool (SWAT) model. A total of 222 climate models were ranked according to the aridity …

Comparison Between Supervised And Unsupervised Learning For Autonomous Delamination Detection Using Impact Echo, Faezeh Jafari, Sattar Dorafshan

Civil Engineering Faculty Publications

Impact echo (IE) is a non-destructive evaluation method commonly used to detect subsurface delamination in reinforced concrete bridge decks. Existing analysis methods are based on frequency domain which can lead to inaccurate assessments of reinforced concrete bridge decks since they do not consider features of the IE signals in the time domain. The authors propose a new method for IE classification by combining features in the time and the frequency domains. The features used in this study included normalized peak values, energy, power, time of peaks, and signal lengths that were extracted from IE signals after they are preprocessed. We …

Parametric Structural Optimization Of A Wheel Using The Flex Representation Method, Gregory John Vernon

Theses and Dissertations

The use of the finite element method within an optimization workflow is fraught with challenges that limit the automation of such workflows. These challenges are inherent to the traditional finite element formulations which are heavily dependent on a manual meshing process that introduces variability that is challenging to account for within an automated workflow. The recently developed flex representation method (FRM) provides a salient solution to the manual meshing process without sacrificing solution accuracy. In response to the development of FRM a global automotive company requested a study to explore the applicability of FRM to one of their sizing-optimization problems: …

Methemoglobin Formation Via Nitric Oxide And Comparison Of Methemoglobin, Deoxyhemoglobin, And Ferrous Nitrosyl Hemoglobin As Potential Mri Contrast Agents, Roya Ayati

Theses and Dissertations

Gadolinium-based contrast agents (GBCAs) are in widespread use to enhance magnetic resonance angiography images for evaluating vascular pathology. However, there are safety concerns and limitations regarding the use of GBCAs. It has been shown that the magnetic resonance imaging (MRI) signal intensity (T1-weighted images) in some of the brain's tissues is higher for patients who had multiple exposures to GBCAs compared to patients who had never had exposure to GBCAs. This implies that GBCAs are not sufficiently removed from body such that GBCAs may potentially have long-term effects on the human body. These potential safety concerns have led to an …

Evaluating Equitable Access To Nutrition In Utah, Emma Stucki

Theses and Dissertations

One of the more recent topics in transportation policy making and project prioritization in DOT's across the United States is how to improve quality of life. This quality of life focus is an intersection of public health and transportation and has many different branches including traffic safety, pollution, active transportation, equity, and accessibility to resources. The topic among these that seems to receive the least attention is equitable access to resources. However, with the proven impact that equitable access to resources has on physical and emotional well-being, as well as economic opportunity it is important to ensure that all populations, …

Scientists And Activists Work To Save The Planet, Myriam G. Vidal Valero

Capstones

Climate change and human intervention in nature are affecting people, ecosystems and ways of living all over the world. This portfolio of environmental pieces showcases the dire consequences of not addressing these issues, how solutions can be reached and the challenges facing those who try to change things.

The Flex Representation Method: Versatile Modeling For Isogeometric Analysis, Christopher David Whetten

Theses and Dissertations

The Flex Representation Method (FRM) leverages unique computational advantages of splines to address limitations in the process of building CAE simulation models from CAD geometric models. Central to the approach is the envelope CAD domain that encapsulates a CAD model. An envelope CAD domain can be of arbitrary topological and geometric complexity. Envelope domains are constructed from spline representations, like U-splines, that are analysis-suitable. The envelope CAD domain can be used to approximate none, some, or all of the features in a CAD model. This yields additional simulation modeling options that simplify the model-building process while leveraging the properties of …