Thermal Destratification Of Air Streams To Improve The Cooling Provisioning Of Air-Cooled Data Centers,
2019
University of Texas at Arlington
Thermal Destratification Of Air Streams To Improve The Cooling Provisioning Of Air-Cooled Data Centers, Anto Joseph Barigala Charles Paulraj
Mechanical and Aerospace Engineering Theses - Archive
Air side economization is an arrangement of duct, damper and automatic control system which together allow introducing outside air to reduce the mechanical cooling during mild or cold weather thereby decrease the energy consumption. The outside ambient air and heated return air from the information technology (IT) pod is mixed inside a dedicated space to achieve a target cold aisle operating temperature and thereby increase economization. Major constrain faced by the design engineers while designing the Mixing Chamber/ Plenum is the stratification of air stream due to the Temperature gradient in the mixed air stream and this stratification can be …
Development Of A One-Equation Turbulence Model Based On K-Ε Closure And Its Extension For Computing Transitional Flows By Including An Intermittency Transport Equation,
2019
Washington University in St. Louis
Development Of A One-Equation Turbulence Model Based On K-Ε Closure And Its Extension For Computing Transitional Flows By Including An Intermittency Transport Equation, Cheng Peng
McKelvey School of Engineering Graduate Student Theses & Dissertations
No abstract provided.
Development Of A Multi-Probe Kelvin Scanner Device For Industrially-Relevant Characterization Of Surface-Activated Carbon Fiber Reinforced Thermoplastic Composites,
2019
Washington University in St. Louis
Development Of A Multi-Probe Kelvin Scanner Device For Industrially-Relevant Characterization Of Surface-Activated Carbon Fiber Reinforced Thermoplastic Composites, Kirby Simon
McKelvey School of Engineering Graduate Student Theses & Dissertations
Carbon fiber reinforced thermoplastic (CFRTP) composites are becoming increasingly attractive materials in manufacturing due to their lightweight nature, mechanical strength, and corrosion resistance. Surface activation of these materials is usually required during processing to increase the bond strength of assemblies (aerospace and automotive industries) or improve adhesion with implants (biomedical industry). Industrially-relevant, nondestructive quality control methods for assessing the activation state of these materials do not currently exist, however. Applying principles discovered through the use of scanning probe microscopy, a multiple-probe Kelvin scanning (MPKS) device has been developed that can assess the uniformity of the activation state of plasma-treated CFRTP …
A Comparison Of Discrete Damage Modeling Methods: The Effect Of Stacking Sequence On Progressive Failure Of The Skin Laminate In A Composite Pi-Joint Subject To Pull-Off Load,
2019
University of Texas at Arlington
A Comparison Of Discrete Damage Modeling Methods: The Effect Of Stacking Sequence On Progressive Failure Of The Skin Laminate In A Composite Pi-Joint Subject To Pull-Off Load, Joseph Keith Novak
Mechanical and Aerospace Engineering Theses - Archive
Discrete damage modeling of composite failure mechanisms including delamination, matrix cracking, and their interactions was performed for the skin laminate in a composite pi-joint test specimen subject to a pull-off load. The skin laminate stacking sequence was varied, and the pull-off load and path of predicted damage were recorded. Within the study two discrete damage modeling tools were used, Abaqus XFEM with a LaRC05 built-in user subroutine and BSAM. Both tools implement failure criteria developed at the NASA Langley Research Center (LaRC) to predict the location of damage initiation and both tools use similar cohesive zone models to model damage …
Silver-Based Microbial Check Valve For Spacecraft Potable Water Systems,
2019
University of Arkansas, Fayetteville
Silver-Based Microbial Check Valve For Spacecraft Potable Water Systems, Rogelio E. Garcia
Chemical Engineering Undergraduate Honors Theses
As human space exploration increases, the development of a more efficient potable water treatment system suited for spacecraft becomes crucial. This Waste-management Education Research Consortium (WERC) challenge was designed to explore the viability of microbial control through the utilization of silver ions as a biocide for possible integration into the Tranquility Node 3 water purification system aboard the International Space Station (ISS). Current systems using iodine risk causing hyperthyroidism from overexposure; however, silver can be safely ingested without this side effect. After researching silver delivery methods including electrochemical ion production, controlled release, or a combination of the two, our team …
On The Anisotropic Behavior Of Electrodes For Electrical-Based Monitoring Of Cfrp Laminated Composites,
2019
Missouri University of Science and Technlogy
On The Anisotropic Behavior Of Electrodes For Electrical-Based Monitoring Of Cfrp Laminated Composites, Khaled Almuhammadi, Arief Yudhanto, Gilles Lubineau
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Electrical impedance tomography (EIT) is a promising structural health monitoring technique for carbon fiber-reinforced polymer (CFRP) composites. EIT technique has been specifically adopted as a non-destructive testing method along with the electrical characterization methods. Electrodes are the primary component in any EIT system because they act as an interface connecting the instrument/hardware to the structure under inspection. Simulation of electrical inspection of CFRP usually assumes the electrodes to be electrically isotropic interfaces. We show here that such isotropic assumption is a very poor approximation. We experimentally investigated the electrodes contact impedance behavior on CFRP-laminated composite specimens for different surface processing …
Internal Strain Assessment Using Fbgs In A Thermoplastic Composite Subjected To Quasi-Static Indentation And Low-Velocity Impact,
2019
Missouri University of Science and Technlogy
Internal Strain Assessment Using Fbgs In A Thermoplastic Composite Subjected To Quasi-Static Indentation And Low-Velocity Impact, M. Mulle, A. Yudhanto, G. Lubineau, R. Yaldiz, W. Schijve, N. Verghese
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We present, for the first time, an experimental investigation of internal strain monitoring in thermoplastic composites subjected to quasi-static indentation and low-velocity impact using embedded fiber Bragg gratings (FBGs). The goal is to highlight the interest and limitations of the in-core instrumentation of glass fiber-reinforced polypropylene laminates subjected to these two classical loading conditions. We propose an instrumentation strategy utilizing FBGs that is expected to provide a reliable set of internal strain values and strain rates, which can be used for the analysis of the damage behavior and the validation of a numerical mesoscale model of laminates. Based on a …
Stability Analysis Of A More General Class Of Systems With Delay-Dependent Coefficients,
2019
Laboratoire des Signaux et Syst`emes (L2S) CentraleSup´elec-CNRS-Universit´e Paris Sud, 3 rue Joliot- Curie 91192 Gif-sur-Yvette cedex, France.
Stability Analysis Of A More General Class Of Systems With Delay-Dependent Coefficients, Chi Jin, Keqin Gu, Islam Boussaada, Silviu-Iulian Niculescu
SIUE Faculty Research, Scholarship, and Creative Activity
This paper presents a systematic method to analyse the stability of systems with single delay in which the coefficient polynomials of the characteristic equation depend on the delay. Such systems often arise in, for example, life science and engineering systems. A method to analyze such systems was presented by Beretta and Kuang in a 2002 paper, but with some very restrictive assumptions. This work extends their results to the general case with the exception of some degenerate cases. It is found that a much richer behavior is possible when the restrictive assumptions are removed. The interval of interest for the …
Impact Of Immersion Cooling On Thermo-Mechanical Properties Of Pcb's And Reliability Of Electronic Packages,
2019
University of Texas at Arlington
Impact Of Immersion Cooling On Thermo-Mechanical Properties Of Pcb's And Reliability Of Electronic Packages, Shrinath Shrinivas Ramdas
Mechanical and Aerospace Engineering Theses - Archive
Immersion cooling technique is used for the thermal management of high-density data centers to avoid overheating of components and failure of servers. However, to use this as a viable cooling technique, the effect of dielectric coolants on the reliability of server components needs to be evaluated. Previous work reported contradicting findings for Young’s modulus of PCBs, providing motivation for this work. This study focuses on effect of immersion cooling on the thermos-mechanical properties of printed circuit board (PCB) and its impact on reliability of electronic packages. Changes in thermo-mechanical properties like Young’s modulus (E), Glass transition temperature (Tg), Coefficient of …
Experimental And Computational Analysis Of A 3d Printed Wing Structure,
2019
Embry-Riddle Aeronautical University
Experimental And Computational Analysis Of A 3d Printed Wing Structure, Aryslan Malik
Doctoral Dissertations and Master's Theses
Correct prediction of aeroelastic response is a crucial part in designing flutter or divergence free aircrafts within a designated flight envelope. The aeroelastic analysis includes specifically tailoring the design in order to prevent flutter (passive control) or eliminate it by applying input on control surfaces (active control). High-fidelity models such as coupled Computational Fluid Dynamics (CFD) - Computational Structural Dynamics (CSD) can obtain full structural and aerodynamic behavior of a deformable aircraft. However, these models are so large that pose a significant challenge from the control systems design perspective. Thus, the development of an aeroelastic modeling software that can be …
Adaptive Commanding Of Control Moment Gyroscopes With Backlash,
2019
Embry-Riddle Aeronautical University
Adaptive Commanding Of Control Moment Gyroscopes With Backlash, Justin G. Bourke
Doctoral Dissertations and Master's Theses
The existence of backlash in mechanical systems provides significant challenges when attempting to control these systems to a high degree of precision. The imperfect meshing of gear or belt teeth deteriorates the performance of position controllers and tracking of small commands, producing unacceptable steady-state offsets, increased rise and settling times. Agile spacecraft often use control moment gyroscopes (CMGs) equipped with gear trains to efficiently provide torque for the fine attitude adjustments used in docking and precision stabilization maneuvers. A theoretical examination and a practical model is developed to study the effectiveness of both proportional-integral (PI) and model referencing adaptive controllers …
Preliminary Test Predictions For Scale Ram-Air Parachute Testing,
2019
Embry-Riddle Aeronautical University
Preliminary Test Predictions For Scale Ram-Air Parachute Testing, Christian A. Guzman Zurita
Doctoral Dissertations and Master's Theses
The present thesis proposes a preliminary analysis to predict the aerodynamic performance for experimental tests of ram-air parachutes in a wind tunnel. A scaled experimental test setup is developed for determining the aerodynamic coefficients of lift (𝐶𝐿) and drag (𝐶𝐷) conducted in a wind tunnel. Additionally, a CFD approach where a steady-state parachute shape defined based on experiments, photographs, and literature, is presented. The accuracy of the simulation depends considerably on the ability to resolve the canopy geometry. Therefore, a CAD geometry generation is implemented for flexible control of the canopy structure by implementing design parameters, e.g., chord, span and …
Development Of Robust Control Laws For Disturbance Rejection In Rotorcraft Uavs,
2019
Embry-Riddle Aeronautical University
Development Of Robust Control Laws For Disturbance Rejection In Rotorcraft Uavs, Johannes Verberne
Doctoral Dissertations and Master's Theses
Inherent stability inside the flight envelope must be guaranteed in order to safely introduce private and commercial UAV systems into the national airspace. The rejection of unknown external wind disturbances offers a challenging task due to the limited available information about the unpredictable and turbulent characteristics of the wind. This thesis focuses on the design, development and implementation of robust control algorithms for disturbance rejection in rotorcraft UAVs. The main focus is the rejection of external disturbances caused by wind influences. Four control algorithms are developed in an effort to mitigate wind effects: baseline nonlinear dynamic inversion (NLDI), a wind …
Low-Tip-Speed High-Torque Proprotor Noise Approximation For Design Cycle Analysis,
2019
Embry-Riddle Aeronautical University
Low-Tip-Speed High-Torque Proprotor Noise Approximation For Design Cycle Analysis, Xavier G. Santacruz
Doctoral Dissertations and Master's Theses
Noise reduction in aviation would enable urban missions that cannot be own with current generation helicopters because of their noisiness. This goal can be achieved by using electric motors as they are quieter and can produce higher torque at lower RPMs. Therefore, a proprotor system can be designed to exploit this characteristic potentially abating noise levels. This research performed noise approximations included with rotor aerodynamics for a single, electric-driven, hovering proprotor by creating a code meant to be used in design cycle analysis. The approximation was based on geometry by using the blade element momentum theory, and calculating the pressure …
Covering Shock Wave Induced Interfacial Mixing: Numerical Study And A Control Primer,
2019
Embry-Riddle Aeronautical University
Covering Shock Wave Induced Interfacial Mixing: Numerical Study And A Control Primer, Erik S. Proaño
Doctoral Dissertations and Master's Theses
This document is aiming toward deepening the understanding of the phenomena of mixing and the effect of the initial conditions in the cylindrical & spherical Richtmyer-Meshkov and Rayleigh-Taylor Instabilities. This work is focused on identifying the most energetic structures of the ow in order to define a reduced order model intended for modeling the evolution of the mixing layer after reshocking the density interface. Initially, Simulations are implemented for the two dimensional case of a cylindrical shock wave convergently approaching an initially wave-like perturbed density discontinuity formed by a target of Sulfur Hexauoride immersed into unshocked air with Atwood number …
Cfd Study Of Taylor-Like Vortices In Swirling Flows,
2019
Embry-Riddle Aeronautical University
Cfd Study Of Taylor-Like Vortices In Swirling Flows, Sattar Panahandehgar
Doctoral Dissertations and Master's Theses
Swirling flows are complex fluid motions that appear in various natural phenomena and man-made devices. Numerous engineering applications such as turbomachinery, jet engine combustion chambers, mixing tanks and industrial burners involve swirling flows. This wide range of applications is due to unique characteristics offered by swirling flows such as increase in mixing rate, heat transfer rate and wall shear stress. In this study the axisymmetric swirling flow behavior in the context of a hybrid rocket engine have been analyzed. While modeling the flow inside a cylindrical chamber using CFD, a similarity with the Taylor vortices instability has been observed. Similar …
Optimal Battery Weight Fraction For Serial Hybrid Propulsion System In Aircraft Design,
2019
Embry-Riddle Aeronautical University
Optimal Battery Weight Fraction For Serial Hybrid Propulsion System In Aircraft Design, Tsz Him Yeung
Doctoral Dissertations and Master's Theses
This thesis focuses on electric propulsion technology associated with serial hybrid power plants most commonly associated with urban air mobility vehicles. While closed form analytical solutions for parallel hybrid aviation cases have been determined, optimized serial hybrid power plants have not seen the same degree of fidelity. Presented here are the analytical relationships between several preliminary aircraft design objectives and the battery weight fraction. These design objectives include aircraft weight, range, operation cost, and carbon emissions. The relationships are based on a serial hybrid electric propulsion architecture from an energy standpoint, and can be applied to hybrid aircraft of different …
A Hybrid Vortex Solution For Radial Equilibrium In Axial Compressors,
2019
Embry-Riddle Aeronautical University
A Hybrid Vortex Solution For Radial Equilibrium In Axial Compressors, Wenyu Li
Doctoral Dissertations and Master's Theses
A hybrid vortex solution using the radial equilibrium equation for three dimensional design in axial compressors is generated. One of the most common used vortex solutions is Free Vortex. However, it ignores the fact that axial velocity varies with radius. The Hybrid Vortex includes axial velocity distribution with radius, which gives a more effective design. A single stage is first designed using the Free Vortex design method. A low hub-to-tip ratio is set to ensure subsonic flow. The axial velocity profile is exported from the CFX solver of the inlet diffuser. Using the Hybrid Vortex solution to the radial equilibrium …
Hypervelocity Impact Analysis Of Hybrid Nanocomposite Sensors For Inflatable Space Structures,
2019
Embry-Riddle Aeronautical University
Hypervelocity Impact Analysis Of Hybrid Nanocomposite Sensors For Inflatable Space Structures, Yachna Gola
Doctoral Dissertations and Master's Theses
Future space exploration requires easy-to-transport, and easy-to-build and deploy space habitats. NASA and Bigelow Aerospace have collaborated so that human habitation can be made safe and easy with inflatable space habitats (Litteken, 2017). One of the biggest threats faced by these structures in outer space is impact damage by micrometeoroid orbital debris (MMOD) traveling at velocities as high as 15 km/s (Lemmens, Krag, Rosebrock, & Carnelli, 2013). This work presents fabrication and testing of hybrid nanocomposites with carbon nanotubes (CNT) and coarse graphene nanoplatelets (GNP) as fillers and flexible epoxy matrix, that are proposed to be used for sensing the …
The Changing Face Of Airmanship And Safety Culture Operating Unmanned Aircraft Systems,
2019
Embry-Riddle Aeronautical University
The Changing Face Of Airmanship And Safety Culture Operating Unmanned Aircraft Systems, Tracy Lamb
Student Works
The notion of using drones for commercial purposes has evolved in the past 5 years from the initial “boom” of excitement around this, somewhat of a novelty and curiosity, to more calculated and sophisticated use of unmanned aircraft systems (UAS), or drones. In the hands of true professionals, drones can offer highly efficient and profitable solutions for industrial, and commercial inspections and other data capturing tasks. The appetite for safe and efficient collection of data is a changing face of safety cultures and how teams and individuals apply airmanship principles, and how inspection crew and UAS crew interact. UAS are …
