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Mechanical and Aerospace Engineering Faculty Research & Creative Works

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Articles 211 - 240 of 808

Full-Text Articles in Aerospace Engineering

Asymmetric Semiconductor Nanostructures For Particle Manipulation, Jaykob Maser, Joshua Rovey Sep 2020

Asymmetric Semiconductor Nanostructures For Particle Manipulation, Jaykob Maser, Joshua Rovey

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We explore how material selection affects the electromagnetic response of closely positioned asymmetric nanostructures. COMSOL Multiphysics is used to model the system, and the materials studied include gold (Au), gallium arsenide (GaAs), indium tin oxide (ITO), and aluminum zinc oxide (AZO). All materials produce average electric field magnitudes on the order of 10 MV/m. We conclude that the ITO and AZO nanostructures produce the most uniform electric field response over the entire domain of incident wavelengths and that GaAs is least thermally stable in a vacuum environment due to its low heat conductivity.

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Characterizing And Modeling The Progressive Damage Of Off-Axis Thermoplastic Plies: Effect Of Ply Confinement, Ditho Pulungan, Arief Yudhanto, Gilles Lubineau Aug 2020

Characterizing And Modeling The Progressive Damage Of Off-Axis Thermoplastic Plies: Effect Of Ply Confinement, Ditho Pulungan, Arief Yudhanto, Gilles Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although the mechanisms of degradation are, overall, quite similar between thermoset and thermoplastic composites, thermoplastic laminates exhibit a higher ductility. Because of that, classical models developed for thermosets fail in predicting accurately the response of thermoplastic-based laminates. Here, we demonstrate that simulations based on the properties identified on isolated thermoplastics unidirectional plies, as usually done for thermosets, result in large errors. This is explained by the significant load-bearing capacity of the ply in the transverse direction that remains even after the first-ply failure, as a result of the confinement provided by adjacent plies. This effect also exists in thermosets, but …

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On The Effect Of Interfacial Patterns On Energy Dissipation In Plastically Deforming Adhesive Bonded Ductile Sheets, Arturo Pascuzzo, Arief Yudhanto, Marco Alfano, Gilles Lubineau Aug 2020

On The Effect Of Interfacial Patterns On Energy Dissipation In Plastically Deforming Adhesive Bonded Ductile Sheets, Arturo Pascuzzo, Arief Yudhanto, Marco Alfano, Gilles Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Toughening of brittle adhesive joints is a topic of great interest for the fabrication of layered structures. Recent experimental work by the authors indicated that spatially varying interface properties (i.e., patterned interfaces obtained using laser irradiation) could tune energy dissipation in plastically deforming adhesive joints. In this study, we use a cohesive zone approach to ascertain the interplay between fracture process zone size and pattern geometry on the overall work of separation. The analysis is carried out in the context of the elasto-plastic peeling response of adhesive bonded ductile thin sheets. The mating surfaces of the adherents feature alternating strips …

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Improving Mode Ii Fracture Toughness Of Secondary Bonded Joints Using Laser Patterning Of Adherends, A. Wagih, R. Tao, A. Yudhanto, G. Lubineau Jul 2020

Improving Mode Ii Fracture Toughness Of Secondary Bonded Joints Using Laser Patterning Of Adherends, A. Wagih, R. Tao, A. Yudhanto, G. Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We improve mode II fracture toughness of secondary bonded joints based on the laser treatment of adherend surfaces. We applied CO2 Laser treatment to adherend surface alternatively with low and high energy, resulting in a repeated pattern of rough and smooth surfaces. We used ENF test to characterize mode II fracture toughness, GII, of the bonded CFRP substrates. The results demonstrated that our proposed pattern arrested the crack propagation and triggered new damage mechanisms, such as adhesive cracking, adhesive failure and crack migration to the other interface. These additional mechanisms, some of them were non-local in nature, resulted in …

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How The Spatial Correlation In Adhesion Properties Influences The Performance Of Secondary Bonding Of Laminated Composites, Xiaole Li, Ran Tao, Arief Yudhanto, Gilles Lubineau Jul 2020

How The Spatial Correlation In Adhesion Properties Influences The Performance Of Secondary Bonding Of Laminated Composites, Xiaole Li, Ran Tao, Arief Yudhanto, Gilles Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Spatial heterogeneity of adhesion properties is known to result in bridging during debonding of secondary bonded composite joints. The ligaments that bridge both substrates have crack-arrest features and thus significantly enhance the fracture resistance of joints. We have investigated the effect of randomly distributed adhesion properties between the adhesive layer and each composite substrate in previous works; however, the spatial correlation of adhesion heterogeneity within or between the substrates and how it effects the failure of secondary bonded composites is still poorly understood. In this current work, we assume that the spatial heterogeneity of adhesion follows a log-normal distribution. The …

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Impulse And Performance Measurements Of Electric Solid Propellant In A Laboratory Electrothermal Ablation-Fed Pulsed Plasma Thruster, Matthew S. Glascock, Joshua L. Rovey, Kurt A. Polzin Jun 2020

Impulse And Performance Measurements Of Electric Solid Propellant In A Laboratory Electrothermal Ablation-Fed Pulsed Plasma Thruster, Matthew S. Glascock, Joshua L. Rovey, Kurt A. Polzin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electric solid propellants are advanced solid chemical rocket propellants that can be controlled (ignited, throttled and extinguished) through the application and removal of an electric current. This behavior may enable the propellant to be used in multimode propulsion systems utilizing the ablative pulsed plasma thruster. The performance of an electric solid propellant operating in an electrothermal ablation-fed pulsed plasma thruster was investigated using an inverted pendulum micro-newton thrust stand. The impulse bit and specific impulse of the device using the electric solid propellant were measured for short-duration test runs of 100 pulses and longer-duration runs to end-of-life, at energy levels …

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Thermal Transport Across The Interface Between Liquid N-Dodecane And Its Own Vapor: A Molecular Dynamics Study, Eric Bird, Jesus Gutierrez Plascencia, Zhi Liang May 2020

Thermal Transport Across The Interface Between Liquid N-Dodecane And Its Own Vapor: A Molecular Dynamics Study, Eric Bird, Jesus Gutierrez Plascencia, Zhi Liang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

There Are Two Possible Thermal Transport Mechanisms at Liquid-Gas Interfaces, Namely, Evaporation/condensation (I.e., Heat Transfer by Liquid-Vapor Phase Change at Liquid Surfaces) and Heat Conduction (I.e., Heat Exchange by Collisions between Gas Molecules and Liquid Surfaces). using Molecular Dynamics (MD) Simulations, We Study Thermal Transport Across the Liquid-Vapor Interface of a Model N-Dodecane (C12H26) under Various Driving Force Conditions. in Each MD Simulation, We Restrict the Thermal Energy to Be Transferred Across the Liquid-Vapor Interface by Only One Mechanism. in Spite of the Complex Intramolecular Interactions in N-Dodecane Molecules, Our Modeling Results Indicate that the Schrage Relationships, Which Were Shown …

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Post-Impact Flexural Behavior Of Carbon-Aramid/Epoxy Hybrid Composites, A. Wagih, T. A. Sebaey, A. Yudhanto, G. Lubineau May 2020

Post-Impact Flexural Behavior Of Carbon-Aramid/Epoxy Hybrid Composites, A. Wagih, T. A. Sebaey, A. Yudhanto, G. Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Hybrid polymeric composites are currently used in aerospace structures due to their specific strength and stiffness as well as larger design space. This paper presents an experimental study on residual flexural strength of impacted Carbon-aramid/Epoxy hybrid composite laminates. Specimens are designed in a sandwich form in which plies of aramid/epoxy represent the core and carbon/epoxy plies play the role of face sheets. This design is expected to take advantage of the high energy absorption capabilities of aramid/epoxy composites. We pre-damage such composites by performing low-velocity impact at different energy levels. Three-point bending tests then are used to measure the residual …

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Fast Reversible Phase Change Silicon For Visible Active Photonics, Letian Wang, Matthew Eliceiri, Yang Deng, Yoonsoo Rho, Wan Shou, Heng Pan, Jie Yao, Costas P. Grigoropoulos Apr 2020

Fast Reversible Phase Change Silicon For Visible Active Photonics, Letian Wang, Matthew Eliceiri, Yang Deng, Yoonsoo Rho, Wan Shou, Heng Pan, Jie Yao, Costas P. Grigoropoulos

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Both amorphous and crystalline silicon are ubiquitous materials for electronics, photonics, and microelectromechanical systems. On-demand control of Si crystallinity is crucial for device manufacturing and to overcome the limitations of current phase-change materials (PCM) in active photonics. Fast reversible phase transformation in silicon, however, has never been accomplished due to the notorious challenge of amorphization. It is demonstrated that nanostructured Si can function as a PCM, since it can be reversibly crystallized and amorphized under nanosecond laser irradiation with different pulse energies. Reflection probing on a single nano disk's phase transformations confirms the distinct mechanisms for crystallization and amorphization. The …

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On Controlling Interfacial Heterogeneity To Trigger Bridging In Secondary Bonded Composite Joints: An Efficient Strategy To Introduce Crack-Arrest Features, Ran Tao, Xiaole Li, Arief Yudhanto, Marco Alfano, Gilles Lubineau Mar 2020

On Controlling Interfacial Heterogeneity To Trigger Bridging In Secondary Bonded Composite Joints: An Efficient Strategy To Introduce Crack-Arrest Features, Ran Tao, Xiaole Li, Arief Yudhanto, Marco Alfano, Gilles Lubineau

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Secondary adhesive bonding of carbon fiber-reinforced polymer laminates is of great interest for the aerospace and automotive industries. However, joint reliability is still a major concern because of fabrication-induced or service-related cracks that are difficult to monitor and can lead to catastrophic failure. In this work, we propose a patterning strategy where the careful design of spatially varying interface properties enables the formation of an adhesive ligament that acts as a crack-arrest feature. Bi-dimensional finite element models of adhesively bonded double cantilever beams were employed to investigate the role of the main parameters of the pattern (i.e., geometrical parameters and …

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Multifidelity Modeling By Polynomial Chaos-Based Cokriging To Enable Efficient Model-Based Reliability Analysis Of Ndt Systems, Xiaosong Du, Leifur Leifsson Mar 2020

Multifidelity Modeling By Polynomial Chaos-Based Cokriging To Enable Efficient Model-Based Reliability Analysis Of Ndt Systems, Xiaosong Du, Leifur Leifsson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This work proposes a novel multifidelity metamodeling approach, the polynomial chaos-based Cokriging (PC-Cokriging). The proposed approach is used for fast uncertainty propagation in a reliability analysis of nondestructive testing systems using model-assisted probability of detection (MAPOD). In particular, PC-Cokriging is a multivariate version of polynomial chaos-based Kriging (PC-Kriging), which aims at combining the advantages of the regression-based polynomial chaos expansions and the interpolation-based Kriging metamodeling methods. Following a similar process as Cokriging, the PC-Cokriging advances PC-Kriging by enabling the incorporation of multifidelity physics information. The proposed PC-Cokriging is demonstrated on two analytical functions and three ultrasonic testing MAPOD cases. The …

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A Molecular Dynamics Study Of Transient Evaporation And Condensation, Zhi Liang, Anirban Chandra, Eric Bird, Pawel Keblinski Mar 2020

A Molecular Dynamics Study Of Transient Evaporation And Condensation, Zhi Liang, Anirban Chandra, Eric Bird, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We Use Molecular Dynamics (MD) Simulations to Study the Transient Evaporation and Condensation of a Pure Fluid Ar in a Nanochannel. in the MD Model, the Evaporation and Condensation of Fluid Ar is Initiated by a Sudden Increase of the Temperature or Periodically Varying the Temperature in the Solid Substrate on One Side of the Nanochannel. in Both Cases, We Find the Transient Evaporation and Condensation Rates Obtained Directly from MD Simulations Are in Good Agreement with the Predictions from the Schrage Relationships. Furthermore, Our Analyses Show that the Kinetics of the Transient Heat and Mass Transfer between the Evaporating …

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Angular Correlation Using Rogers-Szego-Chaos, Christine Schmid, Kyle J. Demars Feb 2020

Angular Correlation Using Rogers-Szego-Chaos, Christine Schmid, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Polynomial chaos expresses a probability density function (pdf) as a linear combination of basis polynomials. If the density and basis polynomials are over the same field, any set of basis polynomials can describe the pdf; however, the most logical choice of polynomials is the family that is orthogonal with respect to the pdf. This problem is well-studied over the field of real numbers and has been shown to be valid for the complex unit circle in one dimension. The current framework for circular polynomial chaos is extended to multiple angular dimensions with the inclusion of correlation terms. Uncertainty propagation of …

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Impartial Sensor Tasking Via Forecasted Information Content Quantification, Matthew J. Gualdoni, Kyle J. Demars Jan 2020

Impartial Sensor Tasking Via Forecasted Information Content Quantification, Matthew J. Gualdoni, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The consistently increasing population of space debris in orbit about the Earth is becoming an increasingly unavoidable problem, necessitating a proper handling of the problem of sensor tasking to effectively and efficiently obtain observations of space objects to maintain catalogs of their positions and velocities. A variety of approaches have been explored to achieve this in an autonomous fashion, assisting with space traffic management. This work presents new statistical analysis of the Kullback–Leibler divergence justifying the use of its expected value in generating sensor schedules. This divergence's use as an objective measure is extended to simultaneously consider, in an impartial …

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Direct Numerical Simulation Of Turbulent Pressure Fluctuations Over A Cone At Mach 8, Junji Huang, Lian Duan, Katya M. Casper, Ross M. Wagnild, Neal P. Bitter Jan 2020

Direct Numerical Simulation Of Turbulent Pressure Fluctuations Over A Cone At Mach 8, Junji Huang, Lian Duan, Katya M. Casper, Ross M. Wagnild, Neal P. Bitter

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations (DNS) were conducted to characterize the pressure fluctuations under the turbulent portion of the boundary layer over a sharp 7◦ half-angle cone at a nominal freestream Mach number of 8 and a unit Reynolds number of Reunit = 13.4 x 106/m. The axisymmetric cone geometry and the flow conditions of the DNS matched those measured in the Sandia Hypersonic Wind Tunnel at Mach 8 (Sandia HWT-8). The DNS-predicted wall pressure statistics, including the root-mean-square (r.m.s.) fluctuations and the power spectral density (PSD), were compared with those measured in the Sandia HWT-8. A good comparison between the DNS …

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Simulation And Modeling Of Cold-Wall Hypersonic Turbulent Boundary Layers On Flat Plate, Junji Huang, Gary L. Nicholson, Lian Duan, Meelan M. Choudhari, Rodney D.W. Bowersox Jan 2020

Simulation And Modeling Of Cold-Wall Hypersonic Turbulent Boundary Layers On Flat Plate, Junji Huang, Gary L. Nicholson, Lian Duan, Meelan M. Choudhari, Rodney D.W. Bowersox

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations (DNS) of flat-plate, zero-pressure-gradient turbulent boundary layers are presented for nominal freestream Mach numbers of 11 and 14 and a highly cooled wall (wall-to-recovery temperature of approximately 0.2). The flow conditions of the DNS are representative of the experimental data for a Mach 11.1 turbulent boundary layer on a flat plate that was tested at Calspan–University of Buffalo Research Center (CUBRC) and the operational conditions of the AEDC Hypervelocity Tunnel No. 9 at Mach 14. The wall shear stress and turbulent heat flux predicted by DNS show good comparisons with those measured at CUBRC and those modeled …

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Numerical Study Of Paramagnetic Elliptical Microparticles In Curved Channels And Uniform Magnetic Fields, Christopher Sobecki, Jie Zhang, Cheng Wang Jan 2020

Numerical Study Of Paramagnetic Elliptical Microparticles In Curved Channels And Uniform Magnetic Fields, Christopher Sobecki, Jie Zhang, Cheng Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We numerically investigated the dynamics of a paramagnetic elliptical particle immersed in a low Reynolds number Poiseuille flow in a curved channel and under a uniform magnetic field by direct numerical simulation. A finite element method, based on an arbitrary Lagrangian-Eulerian approach, analyzed how the channel geometry, the strength and direction of the magnetic field, and the particle shape affected the rotation and radial migration of the particle. The net radial migration of the particle was analyzed after executing a π rotation and at the exit of the curved channel with and without a magnetic field. In the absence of …

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Applications Of Polynomial Chaos-Based Cokriging To Aerodynamic Design Optimization Benchmark Problems, Jethro Nagawkar, Leifur Leifsson, Xiaosong Du Jan 2020

Applications Of Polynomial Chaos-Based Cokriging To Aerodynamic Design Optimization Benchmark Problems, Jethro Nagawkar, Leifur Leifsson, Xiaosong Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this work, the polynomial chaos-based Cokriging (PC-Cokriging) is applied to a benchmark aerodynamic design optimization problem. The aim is to perform fast design optimization using this multifidelity metamodel. Multifidelity metamodels use information at multiple levels of fidelity to make accurate and fast predictions. Higher amount of lower fidelity data can provide important information on the trends to a limited amount of high-fidelity (HF) data. The PC-Cokriging metamodel is a multivariate version of the polynomial chaos-based Kriging (PC-Kriging) metamodel and its construction is similar to Cokriging. It combines the advantages of the interpolation-based Kriging metamodel and the regression-based polynomial chaos …

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A B-Spline-Based Generative Adversarial Network Model For Fast Interactive Airfoil Aerodynamic Optimization, Xiaosong Du, Ping He, Joaquim R.R.A. Martins Jan 2020

A B-Spline-Based Generative Adversarial Network Model For Fast Interactive Airfoil Aerodynamic Optimization, Xiaosong Du, Ping He, Joaquim R.R.A. Martins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Airfoil aerodynamic optimization is of great importance in aircraft design; however, it relies on high-fidelity physics-based models that are computationally expensive to evaluate. In this work, we provide a methodology to reduce the computational cost for airfoil aerodynamic optimization. Firstly, we develop a B-spline based generative adversarial networks (BSplineGAN) parameterization method to automatically infer design space with sufficient shape variability. Secondly, we construct multi-layer neural network (MNN) surrogates for fast predictions on aerodynamic drag, lift, and pitching moment coefficients. The BSplineGAN has a relative error lower than 1% when fitting to UIUC database. Verification of MNN surrogates shows the root …

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A Brief Review On 3d Bioprinted Skin Substitutes, Fateme Fayyazbakhsh, Ming-Chuan Leu Jan 2020

A Brief Review On 3d Bioprinted Skin Substitutes, Fateme Fayyazbakhsh, Ming-Chuan Leu

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Global Escalating Cases of Skin Donor Shortage for Patients with Severe Wounds Warn the Vital Need for Alternatives to Skin Allografts. over the Last Three Decades, Research in the Skin Regeneration Area Has Addressed the Unmet Need for Artificial Skin Substitutes. 3D Bioprinting is a Promising Innovative Technology to Accurately Fabricate Skin Constructs based on Natural or Synthetic Bioinks, Whether Loaded or Not Loaded with Native Skin Cells (I.e., Keratinocytes and Fibroblasts) or Stem Cells in the Prescribed 3D Hierarchal Structure to Create Artificial Multilayer and Single Cell-Laden Construct. in This Paper, the Recent Developments in 3D Bioprinting for …

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Robustness Metric For Robust Design Optimization Under Time-And Space-Dependent Uncertainty Through Metamodeling, Xinpeng Wei, Xiaoping Du Jan 2020

Robustness Metric For Robust Design Optimization Under Time-And Space-Dependent Uncertainty Through Metamodeling, Xinpeng Wei, Xiaoping Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Product performance varies with respect to time and space in many engineering applications. This paper discusses how to measure and evaluate the robustness of a product or component when its quality characteristics (QCs) are functions of random variables, random fields, temporal variables, and spatial variables. At first, the existing time-dependent robustness metric is extended to the present time-and space-dependent problem. The robustness metric is derived using the extreme value of the quality characteristics with respect to temporal and spatial variables for the nominal-the-better type quality characteristics. Then, a metamodel-based numerical procedure is developed to evaluate the new robustness metric. The …

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Erratum: Minimization Of The Kullback-Leibler Divergence For Nonlinear Estimation (Journal Of Guidance, Control, And Dynamics, (2017), 10.2514/1.G002282), Jacob E. Darling, Kyle J. Demars Jan 2020

Erratum: Minimization Of The Kullback-Leibler Divergence For Nonlinear Estimation (Journal Of Guidance, Control, And Dynamics, (2017), 10.2514/1.G002282), Jacob E. Darling, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Erratum Notice In the original article [https://doi.org/10.2514/1.G002282], Eqs. (16b) and (18b) were typeset as (Formula Presented) which incorrectly show that the posterior covariance at time tk, denoted by Pk, is calculated about the prior mean, m−k. The correct forms of these equations are given by (Formula Presented) which show that Pk is calculated about the posterior mean, mk. All resulting analyses and simulations reported in the article were performed using the correct forms of the equations.

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Direct Numerical Simulations Of Acoustic Disturbances In Various Rectangular Nozzle Configurations, Nathaniel Hildebrand, Meelan M. Choudhari, Lian Duan Jan 2020

Direct Numerical Simulations Of Acoustic Disturbances In Various Rectangular Nozzle Configurations, Nathaniel Hildebrand, Meelan M. Choudhari, Lian Duan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We perform Direct Numerical Simulations (DNS) to study the acoustic freestream disturbances radiating from the turbulent boundary layers along the contoured nozzle walls of a hypersonic wind tunnel with a rectangular test section. To begin with, the effects of the spanwise end walls are suppressed by confining the spanwise computational domain to a finite segment of the overall nozzle cross section and by imposing periodic boundary conditions across that spanwise domain. Besides providing a building-block configuration to reveal partial effects of the enclosed acoustic environment within the wind tunnel, these computations serve as a steppingstone toward the goal of fully-3D …

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Information-Based Particle Flow For High Uncertainty Estimation, Kari C. Ward, Kyle J. Demars Jan 2020

Information-Based Particle Flow For High Uncertainty Estimation, Kari C. Ward, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This work presents a new formulation of the Gaussian particle flow filter derived using an information theoretic approach. The developed information flow addresses two problems with Gaussian particle flow: the lack of inherent meaning in the flow parameters and the inability to easily include modifications for a non-Bayesian update. Equivalency between Gaussian particle flow and information flow is established using a linear, Gaussian example. An orbit determination simulation with high initial uncertainty is used to demonstrate the consistent, robust performance of the information flow filter in situations where the extended Kalman filter fails.

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Propagation Of Errors Through Coning, Sculling, And Scrolling Correction Algorithms, James D. Brouk, Kyle J. Demars Jan 2020

Propagation Of Errors Through Coning, Sculling, And Scrolling Correction Algorithms, James D. Brouk, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper investigates the propagation of estimation errors through a common coning, sculling, and scrolling architecture used in modern day inertial navigation systems. Coning, sculling, and scrolling corrections often have an unaccounted-for effect on the error statistics of inertial measurements used to describe the state and uncertainty propagation for position, velocity, and attitude estimates. Through the development of an error analysis for a set of coning, sculling, and scrolling algorithms, mappings of the measurement and estimation errors through the correction term are adaptively generated. Using the developed mappings, an efficient and consistent propagation of the state and uncertainty, within the …

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Impact Of Considering And Neglecting States On Descent-To-Landing Navigation, Kyle J. Demars, Kari C. Ward Jan 2020

Impact Of Considering And Neglecting States On Descent-To-Landing Navigation, Kyle J. Demars, Kari C. Ward

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper develops a novel square-root formulation of the consider/neglect Kalman filter for navigation applications. The proposed filter partitions system parameters into three distinct categories: those to be estimated by the filter, those whose contribution to the system can be considered without explicitly estimating them, and those with sufficiently low effect on the system such that their contribution can be neglected altogether. Discussion on appropriate selection of consider and neglect parameters is provided with specific attention given to descent-to-landing navigation. Monte Carlo simulations and analysis are performed to assess the performance of the square-root consider/neglect filter.

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Optimization Strategies For Myopic And Forecasted Divergence-Based Sensor Tasking Objectives, Matthew J. Gualdoni, Kyle J. Demars Jan 2020

Optimization Strategies For Myopic And Forecasted Divergence-Based Sensor Tasking Objectives, Matthew J. Gualdoni, Kyle J. Demars

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In light of the ever-increasing value of space assets operating in the presence of a continuously growing population of space objects in orbit about Earth, space situational awareness is becoming more crucial than ever. The process of tracking and maintaining estimates for the numerous assets and space objects is a complex and highly demanding problem, as it requires robust state estimates in the presence of sparse data. As the number of space objects greatly outweighs the number of available sensors, a sensor tasking policy is necessary to properly utilize the available sensor resources in a way that ensures targets are …

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Thermodynamic Properties Of Hydroxylammonium Nitrate-Based Electric Solid Propellant Plasma, Matthew S. Glascock, Patrick D. Drew, Joshua L. Rovey, Kurt A. Polzin Jan 2020

Thermodynamic Properties Of Hydroxylammonium Nitrate-Based Electric Solid Propellant Plasma, Matthew S. Glascock, Patrick D. Drew, Joshua L. Rovey, Kurt A. Polzin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Electric solid propellants are advanced solid chemical rocket propellants controlled by electric current. An electric solid propellant may also be used in an electric propulsion system: specifically, an ablative pulsed plasma thruster. Previous experiments with the electric solid propellant known as high-performance electric propellant, or HIPEP, suggest its ablation processes are similar to the traditional propellant polytetrafluoroethylene (C2 F4). Better understanding of the ablation and the resulting propulsion performance of HIPEP requires a model of its vapor composition, bulk plasma quantities, and thermodynamic properties. Such a model was developed and favorably compared with previous analogous model predictions found in the …

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Design And Analysis Of Descent-To-Landing Navigation Incorporating Terrain Effects, Kari C. Ward, Gunner S. Fritsch, J. Cameron Helmuth, Kyle J. Demars, James S. Mccabe Jan 2020

Design And Analysis Of Descent-To-Landing Navigation Incorporating Terrain Effects, Kari C. Ward, Gunner S. Fritsch, J. Cameron Helmuth, Kyle J. Demars, James S. Mccabe

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This study investigated the ability of a navigation filter to process multiple terrain-based sensors, such as slant-range, slant-speed, and terrain relative navigation sensors, during a descent-to-landing scenario to estimate the state of a landing vehicle. The filtering technique leveraged was based upon a factorized form of the multiplicative extended Kalman filter, and terrain-based measurements were fused with star camera and inertial measurement unit sensor returns to estimate the position, velocity, and attitude of the landing vehicle. Monte Carlo simulations were carried out to assess the performance of the navigation filter along a lunar descent trajectory, as well as the consistency …

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Impact Of Isolated Atmospheric Aging Processes On The Cloud Condensation Nuclei Activation Of Soot Particles, Franz Friebel, Prem Lobo, David Neubauer, Ulrike Lohmann, Saskia Drossaart Van Dusseldorp, Evelyn Mühlhofer, Amewu A. Mensah Dec 2019

Impact Of Isolated Atmospheric Aging Processes On The Cloud Condensation Nuclei Activation Of Soot Particles, Franz Friebel, Prem Lobo, David Neubauer, Ulrike Lohmann, Saskia Drossaart Van Dusseldorp, Evelyn Mühlhofer, Amewu A. Mensah

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The largest contributors to the uncertainty in assessing the anthropogenic contribution in radiative forcing are the direct and indirect effects of aerosol particles on the Earth's radiative budget. Soot particles are of special interest since their properties can change significantly due to aging processes once they are emitted into the atmosphere. Probably the largest obstacle for the investigation of these processes in the laboratory is the long atmospheric lifetime of 1 week, requiring tailored experiments that cover this time span. This work presents results on the ability of two types of soot, obtained using a miniCAST soot generator, to act …

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