Organizational Unit:
George W. Woodruff School of Mechanical Engineering
George W. Woodruff School of Mechanical Engineering
Permanent Link
Research Organization Registry ID
Description
Previous Names
Parent Organization
Parent Organization
Organizational Unit
Includes Organization(s)
Organizational Unit
Organizational Unit
Organizational Unit
Organizational Unit
Organizational Unit
ArchiveSpace Name Record
4978 results
Publication Search Results
Now showing
1 - 10 of 4978
-
ItemRaw Data for "Development of a novel point-of-care device to monitor arterial thrombosis"(Georgia Institute of Technology, 2025-01) Bresette, ChristopherRaw data related to the paper, "Development of a novel point-of-care device to monitor arterial thrombosis", including Capillary Tube Diameters, Vacuum Pressure Measurements, Multiple Test Variability, End Volume vs Occlusion Time, Control End Volume vs Antiplatelet End Volume, Test Device vs PFA-100 correlation.
-
ItemData and CAD files for the article "AI-Driven Universal Lower-Limb Exoskeleton System for Community Ambulation"(Georgia Institute of Technology, 2024-11-14) Lee, Dawit ; Lee, Sanghyub ; Young, AaronResearch data files and Computer-Aided Design (CAD) files to accompany the article "AI-Driven Universal Lower-Limb Exoskeleton System for Community Ambulation"
-
ItemEncrypted Model Reference Adaptive Control with False Data Injection Attack Resilience via Somewhat Homomorphic Encryption-Based Overflow Trap(Georgia Institute of Technology, 2024-08) Ueda, Jun ; Blevins, JacobCloud-based control is prevalent in many modern control applications. Such applications require security for the sake of data secrecy and system safety. The presented research proposes an encrypted adaptive control framework that can be secured for cloud computing with encryption and without issues caused by encryption overflow and large execution delays. This objective is accomplished by implementing a somewhat homomorphic encryption (SHE) scheme on a modified model reference adaptive controller with accompanying encryption parameter tuning rules. Additionally, this paper proposes a virtual false data injection attack (FDIA) trap based on the SHE scheme. The trap guarantees a probability of attack detection by the adjustment of encryption parameters, thus protecting the system from malicious third parties. The formulated algorithm is then simulated, verifying that after tuning encryption parameters, the encrypted controller produces desired plant outputs while guaranteeing detection or compensation of FDIAs. This is a preprint version of the manuscript.
-
ItemModeling of Thermal Storage Silos and Heat Exchanger for Particle-Based Concentrated Solar Power(Georgia Institute of Technology, 2024-07-27) Marton, MatthewNext generation concentrated solar power (CSP) plants are envisioned to use carbon coated particles like HSP 60/40 as a highly efficient heat transfer fluid. There has been previous work on the development of subcomponent models, but these existing models are complex and computationally expensive. The goal of this work is the development of simpler thermal models of a particle storage silo and a particle-to-super critical carbon dioxide heat exchanger. These models are then combined together into a continuous system where the particles flow from the storage system through the heat exchanger. Parametric studies are then performed on both the individual and combined components to test the impact of changing design and operational variables on the thermal response. The models are developed in a way for later use in system level CSP models.
-
ItemAn Analytical Model for Oscillating Heat Pipe Performance and Experimental Testing of a Novel Helix-Shaped Design(Georgia Institute of Technology, 2024-07-27) Pawlick, MaxwellThe research presented focuses on the development and assessment of a novel mechanistic model for oscillating heat pipes (OHPs), also known as pulsating heat pipes (PHPs) and the development of a novel helix-shaped OHP design inspired by insights gained from the model developed. OHPs are passive heat transfer devices with potential applications in fields such as electronics cooling, heat recovery systems, and hypersonic vehicles. Despite their potential, their adoption in industry has been slow due to the lack of reliable design tools. The complex physics governing OHP performance and the need for accurate modeling techniques have hindered the development of such tools. An OHP consists of a sealed capillary channel filled with alternating liquid slugs and vapor bubbles. When a temperature difference is present, evaporation and condensation cause fluid motion, leading to passive convective heat transfer. Traditional OHP modeling approaches, ranging from experimental correlations to complex 3D computational models, have had limited success in providing rapid and reliable performance predictions without experimental data. This research aims to develop a mechanistic model capable of predicting the performance of a basic closed-loop OHP design without experimental input. The model is intended to predict temperature profiles and performance trends, allowing designers to narrow down potential OHP designs for further analysis. Insights gained from the model were used to design a novel helix-shaped OHP, which was designed to leverage buoyancy-driven circulation flow for improved performance. The research establishes that analytical modeling methods can significantly enhance the understanding and prediction of OHP performance. The contributions of this study include a comprehensive evaluation of OHP literature, identifying various operating modes that influence performance, developing an analytical framework for understanding some of these modes, and using this framework to develope and test a novel OHP design. This operating mode framework classifies OHP operation based on liquid distribution, fluid motion type, and flow regime, providing a basis for comparing different OHP designs. The analytical model successfully predicted the temperature drop across multiple OHP datasets, although it has limitations in certain operating modes and complex geometries. To address these limitations, the research suggests augmenting the model with machine learning techniques, particularly for phenomena that are difficult to model analytically, such as oscillation amplitude in designs with flooded condensers. Experimental validation of the novel helix-shaped OHP demonstrated that the design generally improved the effective thermal conductivity and maximum heat transport capacity relative to a control design. Further studies on helix-shaped OHPs with different sizes and working fluids are recommended to extend the advantages of this design. Additionally, the insights gained from the model provide further opportunity for other novel designs that improve performance. This work represents significant progress in understanding and modeling OHP operation. The analytical model developed and the insights into OHP mechanisms provide a foundation for designing and optimizing OHPs for various applications. Further research that utilizes machine learning techniques to predict the most complex mechanisms in OHP operation is encouraged to increase the reliability and accuracy of the model. This work paves the way for broader and more effective use of OHPs in fields such as energy recovery and thermal management, which will contribute to a shift in how OHP technology is viewed and utilized in both academia and industry.
-
ItemThe interplay of length and force feedback in regulating joint and limb impedance and inter-joint coordination(Georgia Institute of Technology, 2024-07-27) Govindaraj, ThendralNeural feedback pathways arise from a variety of sensory receptors. The firing of muscle spindles is related to length and velocity, while Golgi tendon organs measure active contractile force. Understanding the functions of these pathways during voluntary movement is important because they become disrupted in Spinal Cord Injury (SCI) and stroke. Most spindle pathways are relatively localized, but some are inter-joint. These inter-joint pathways may play a role in regulating whole limb properties. Experiments have shown that force-dependent feedback can be widely distributed and asymmetric between a given muscle pair. Additionally, force feedback is modulated according to the task and condition, such as slope walking and SCI. Although the muscle-level distributions of force feedback in the feline hindlimb have been measured under different conditions, it is not known how these distributions regulate limb mechanics (impedance and inter-joint coordination). To investigate how inter-joint spinal reflex feedback influences joint and limb impedance and inter-joint coordination under locomotion-like conditions, we developed a novel computational modeling and analysis framework. Our hypothesis was that length and force feedback modulate joint and limb impedance in a task-dependent manner while maintaining inter-joint coordination. To address this hypothesis, we developed a set of novel computational models and an analysis framework. Our first model includes an infinitely thin rod with viscoelastic properties (intrinsic + reflex) incorporated into a single joint, and the analysis framework evaluates the impedance when a sinusoidal torque is applied to the joint. Using this model and analysis framework, the goal of aim 1 was to investigate the influence of muscle spindle and Golgi tendon organ feedback on the impedance regulation of a single joint. We found that different combinations of spindle and tendon organ gains can achieve the same impedance, even with 20% lower intrinsic impedance. In support of the stiffness regulation hypothesis, impedance and internal regulation can be controlled separately because changing the ratio of length to force feedback can modify the impedance without altering the compensation for fatigue. To test an extension of the stiffness regulation hypothesis to multi-joint systems, we developed a computational model with two infinitely thin rods, intrinsic viscoelastic properties incorporated into two joints, and reflexes represented at the joint level. The analysis framework evaluates the whole limb and joint apparent impedances and inter-joint coordination when a sinusoidal endpoint force is applied to the end of the distal segment. We varied the direction of the endpoint force to simulate different locomotion tasks and combinations of joints. The goal of aims 2 and 3 is to evaluate the influence of inter-joint length and force feedback on the regulation of whole limb impedance and on inter-joint coordination. As hypothesized, inter-joint length and force feedback modulate limb impedance in a task-dependent manner over part of a functionally relevant range of endpoint force directions, which has implications for rehabilitation after incomplete SCI. The two joint model and analysis framework can provide a template for the control of multi-joint exoskeletons. The results in this dissertation give insight into how reflex gains are modulated to achieve the impedance required for certain tasks and conditions in all animals with multi segmented limbs.
-
ItemDigital Twin Design and Autonomous Control of Bioreactor Systems for Human Immune Cell Expansion(Georgia Institute of Technology, 2024-07-27) Kanwar, BharatImmune cell therapy is a rapidly growing field with immense clinical potential for several indications, including regenerating tissue, immunomodulation, and engineered cells for disease removal. As a nascent industry, biomanufacturing of these cell therapies involves lengthy manual protocols which leads to increased risk of failed or inconsistent cell product. This work proposes a framework for designing digital-twin models for bioreactor platforms that are inherently designed to integrate novel sensors, imaging, process controls, and perfusion. This framework consists of a modular digital twin that can model the relevant fluid dynamics of convection, diffusion and osmosis and cell fluxes of the bioreactor platform. Given the sterility requirements for living cell expansion, measurement of important parameters during the process is often untenable. This work proposes methods to compute unmeasured states and parameters from measured ones with an Extended Kalman Filter and predictive models to explore the domain of critical process parameters to control and measure. This framework then proposes an optimal-cost Linear Quadratic Regulator control architecture to regulate nutrients and cell output of the bioreactor process and demonstrates bioreactor process control with improved hMSC expansion in a hollow fiber bioreactor and improved T cell expansion in a vertical wheel bioreactor.
-
ItemNumerical Analysis of Fiber Orientation Kinetics(Georgia Institute of Technology, 2024-07-26) Karahan, Dogukan TugberkTransport of fibrous matter is encountered in modern industrial applications such as papermaking, concrete reinforcement, and injection molding. The end-product quality in these applications is strongly dependent on flow properties and fiber orientation. The bulk deformation of the suspensions is generally modeled by non-Newtonian constitutive relations, and fiber orientation modeling is based on the Fokker-Planck equation. Using these ideas, this work presents a numerical analysis of fiber orientation kinetics for suspensions up to the semiconcentrated regime, where the effects of the flow and suspension on fiber orientation are represented on by a rotational diffusion coefficient. To this end, probabilistic measures for the fiber orientation, namely the fiber orientation probability density function (FOPD) and orientation tensors, are employed. The rheology of the suspension is modeled as a shear-thinning Herschel-Bulkley (HB) fluid. Flows of HB fluids are studied for laminar and turbulent flows in canonical geometries. An extensive statistical analysis with new data is presented to demonstrate the effects of yield stress and shear thinning on the flow characteristics and fiber orientation. Fiber orientation is obtained at a single point for simple flows and in contracting channels. For the former, a new solver is developed to obtain the FOPD. The results show significant improvements over existing results, and new ideas for the rotational diffusion coefficient for semiconcentrated suspensions are developed. For contracting channels, the governing equations for second-order orientation tensor are solved in order to obtain fiber orientation in practically relevant applications. A systematic analysis is presented to show the effect of the rheological properties and the rotational diffusion coefficient in these applications. It is demonstrated that the fiber orientation changes non-linearly in response to changes in the rheology and rotational diffusion coefficient.
-
Item1-D Mathematical Modeling to Study the Mechanics of Pregnancy and Preeclampsia, Lymphatics, and Peripheral Artery Disease(Georgia Institute of Technology, 2024-07-22) Sedaghati, FarbodThe dissertation explores the critical role of mathematical modeling in understanding complex biological systems. Despite extensive research, certain conditions such as preeclampsia (PE), lymphedema, and peripheral arterial disease (PAD) remain insufficiently studied. These disorders are intricately connected to the mechanical environment, involving factors like fluid transport, solid mechanical responses, and growth and remodeling mechanisms. For example, in PE, impaired vascular remodeling of the uterine vasculature leads to reduced blood flow to the placenta, causing hypertension and associated complications. Hemodynamics, essential for normal physiological function, is often examined through mathematical models. While simpler models fail to capture axial wave behavior, higher-order models, such as 1-D models, offer a balance between complexity and computational efficiency. These models account for spatial variations along each vessel axis, providing insights into cardiovascular regions with valves or bifurcations. The dissertation aims to evaluate the utility of 1-D mathematical models in investigating biological phenomena influenced by wall phenotype, such as during pregnancy. The goal is to validate whether these models, combined with established concepts like growth and remodeling, can analyze biological events where the vascular system significantly affects fluid transport mechanisms.
-
ItemDeveloping Blue and Green Ammonia Infrastructure: Insights into Operations, Economics, and Distribution(Georgia Institute of Technology, 2024-07-19) Fernandez Otero, Carlos ArturoDeveloping blue and green ammonia infrastructure is essential to meet the rising demand for fertilizers while minimizing the environmental impacts of fertilizer production. Traditional ammonia production methods, such as the Haber-Bosch process, are energy-intensive and heavily reliant on fossil fuels, leading to significant carbon emissions. Alternatives, such as blue ammonia, which involves carbon capture and storage, and green ammonia, which utilizes electrification with renewable energy, offer more sustainable options. This dissertation investigates the operations, economics, and distribution of blue and green ammonia infrastructure, integrating thermodynamic, economic, environmental, and social metrics to evaluate low-carbon ammonia production technologies. The aim is to identify optimal deployment strategies for these technologies, considering future energy markets and geographic resource availability. Chapter 1 discusses the significance of ammonia in synthetic fertilizers and global food production, and the future of ammonia as an energy vector. The current Haber-Bosch process, which is centralized and fossil fuel-dependent, results in high CO2 emissions. Blue and green ammonia provide viable pathways to decarbonize ammonia production. Chapter 2 is a literature review that covers various ammonia production technologies, including gray, blue, and green Haber-Bosch processes, and emerging electrochemical methods. It also discusses the techno-economics, renewable integration, and ammonia storage and distribution methods. Chapter 3 estimates projections for future ammonia and nitric acid markets, emphasizing electrochemical nitrogen and nitrate reduction technologies. By predicting the market size and value for ammonia and nitric acid by 2050, Chapter 3 highlights the need for green alternatives to reduce carbon emissions. Chapter 4 expands the analysis by including energy consumption, costs, and emissions associated with green and blue ammonia production under different future energy market scenarios. Chapter 4 underscores the importance of renewable energy sources, carbon capture, and policy in reducing the carbon footprint of ammonia production. Chapter 5 presents an analysis of decentralized ammonia production using renewable energy sources. Chapter 5 presents an optimization model of production and distribution networks using techno-economic models and multi-objective optimization. The findings suggest that integrating renewable energy with ammonia production can significantly lower emissions and costs, especially when production is decentralized.