Digital Commons Network^™

The Applications Of Intumescent Technologies In Support Of D&D Activities Across The Doe Complex, Joshua Alan Nunez

FIU Electronic Theses and Dissertations

Nuclear facilities in the process of Deactivation and Decommissioning (D&D) face several enormous challenges. Decommissioning is only part of the final shutdown process of a nuclear facility. The majority of the DOE facilities, like most industries, face fire hazards or extreme heat conditions. This study aims to research, test, and validate the operational performance of commercially available polyurethane expanding intumescent foams as potential fixatives for immobilizing residual contamination while preserving fire resiliency. Due to the novelty of this unique problem set and approach, existing international standards (ASTM/NIST/etc.) were reviewed for best-fit platforms with which to build testing protocols from. Once …

High-Power Biofuel Cells Based On Threedimensional Reduced Graphene Oxide/ Carbon Nanotube Micro-Arrays, Yin Song, Chunlei Wang

Department of Mechanical and Materials Engineering

Miniaturized enzymatic biofuel cells (EBFCs) with high cell performance are promising candidates for powering next-generation implantable medical devices. Here, we report a closed-loop theoretical and experimental study on a micro EBFC system based on three-dimensional (3D) carbon micropillar arrays coated with reduced graphene oxide (rGO), carbon nanotubes (CNTs), and a biocatalyst composite. The fabrication process of this system combines the top–down carbon microelectromechanical systems (C-MEMS) technique to fabricate the 3D micropillar array platform and bottom–up electrophoretic deposition (EPD) to deposit the reduced rGO/CNTs/enzyme onto the electrode surface. The Michaelis–Menten constant KM of 2.1 mM for glucose oxidase (GOx) on the …

Many-Objective Hybrid Optimization Under Uncertainty With Applications, Sohail Reddy

FIU Electronic Theses and Dissertations

A novel method for solving many-objective optimization problems under uncertainty was developed. It is well known that no single optimization algorithm performs best for all problems. Therefore, the developed method, a many-objective hybrid optimizer (MOHO), uses five constitutive algorithms and actively switches between them throughout the optimization process allowing for robust optimization. MOHO monitors the progress made by each of the five algorithms and allows the best performing algorithm more attempts at finding the optimum. This removes the need for user input for selecting algorithm as the best performing algorithm is automatically selected thereby increasing the probability of converging to …

Toward A Fast And Accurate Modeling Strategy For Thermal Management In Air-Cooled Data Centers, Long Tran Bao Phan

FIU Electronic Theses and Dissertations

Computational fluid dynamics (CFD) has become a popular tool compared to experimental measurement for thermal management in data centers. However, it is very time-consuming and resource-intensive when used to model large-scale data centers, and may not be ready for real-time thermal monitoring. In this thesis, the two main goals are first to develop rapid flow simulation to reduce the computing time while maintaining good accuracy, and second, to develop a whole building energy simulation (BES) strategy for data center modeling. To achieve this end, hybrid modeling and model training methodologies are investigated for rapid flow simulation, and a multi-zone model …

Dynamics Of Falling Droplet Under Effects Of Electric Fields, Esmaiil Ghasemisahebi

FIU Electronic Theses and Dissertations

Physical properties and especially the size of drops are important parameters in many industrial and medical applications. High voltage electric field is one of the effective means to control the final size of drops during the fabrication process which could greatly influence the final size of the product. Therefore a detailed study of electric field effect on a liquid drop is very important. In this work deformation and fragmentation of a falling droplet under gravity and electric force have been studied numerically. The electric force is used as an effective external controlling mechanism to influence the deformation of a drop. …

A Computational Approach For Modeling Plasma Sprayed Coatings From Splat To Bulk Deposits, Sadhana Bhusal

FIU Electronic Theses and Dissertations

In this study, a multi-pronged computational approach is developed to predict the effect of spray parameters on aluminum oxide splat formation and mechanical properties of the coatings. The splat morphology is investigated using computational fluid dynamics approach. Simulated splat morphologies show a good agreement with the experimentally obtained splats. Three-dimensional coating structure is constructed using the stochastic approach using simulated splat morphologies. Finite Element Analysis is used to compute the elastic modulus of the coating. An inter-splat correction factor is introduced which considers inter-splat cracks, interface bonding and other effects like curling of splats and splat sliding. After the correction …

Design Of High Temperature Ti–Al–Cr–V Alloys For Maximum Thermodynamic Stability Using Self-Organizing Maps, Rajesh Jha, George S. Dulikravich

Department of Mechanical and Materials Engineering

Data generated for the Ti–Al–Cr–V system of metallic alloys from our previous publication, where the composition of 102 alloys were computationally Pareto optimized with the objective of simultaneously maximizing the Young’s modulus and minimizing density for a range of temperatures, was the starting point of the current research, where compositions at different temperatures of these alloys were analyzed for phase stability in order to generate new data for compositions and volume fractions of stable phases at various temperatures. This resulted in a large dataset where a lot of data were still missing as all the phases are not stable at …

Design Of High Temperature Ti–Al–Cr–V Alloys For Maximum Thermodynamic Stability Using Self-Organizing Maps, Rajesh Jha, George S. Dulikravich

Department of Mechanical and Materials Engineering

Data generated for the Ti–Al–Cr–V system of metallic alloys from our previous publication, where the composition of 102 alloys were computationally Pareto optimized with the objective of simultaneously maximizing the Young’s modulus and minimizing density for a range of temperatures, was the starting point of the current research, where compositions at different temperatures of these alloys were analyzed for phase stability in order to generate new data for compositions and volume fractions of stable phases at various temperatures. This resulted in a large dataset where a lot of data were still missing as all the phases are not stable at …

A Constructal Approach To The Design Of Inflected Airplane Wings, Shanae Powell

FIU Electronic Theses and Dissertations

Aeroelastic instabilities such as flutter can be accurately captured by state-of-the-art aeroelastic analysis methods and tools. However, these tools and methods fall short in exposing the reasons behind the occurrence of such instabilities. In this research, the constructal law is used to discover the main cause of the variation in the flutter speed and stress distribution for inflected aircraft wings when compared to its uninflected counterpart. This law considers the design as a physics phenomenon and uses an evolutionary flow principle to explain and predict the occurrence of energy flow configurations (i.e. the flow of stresses throughout the structure).

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