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Articles 301 - 330 of 1287
Full-Text Articles in Engineering
Application Of Quantum-Markov Open System Models To Human Cognition And Decision, Jerome Busemeyer, Qizi Zhang, S. N. Balakrishnan, Zheng Wang
Application Of Quantum-Markov Open System Models To Human Cognition And Decision, Jerome Busemeyer, Qizi Zhang, S. N. Balakrishnan, Zheng Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Markov processes, such as random walk models, have been successfully used by cognitive and neural scientists to model human choice behavior and decision time for over 50 years. Recently, quantum walk models have been introduced as an alternative way to model the dynamics of human choice and confidence across time. Empirical evidence points to the need for both types of processes, and open system models provide a way to incorporate them both into a single process. However, some of the constraints required by open system models present challenges for achieving this goal. The purpose of this article is to address …
Asymmetric Semiconductor Nanostructures For Particle Manipulation, Jaykob Maser, Joshua Rovey
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.
Characterizing And Modeling The Progressive Damage Of Off-Axis Thermoplastic Plies: Effect Of Ply Confinement, Ditho Pulungan, Arief Yudhanto, Gilles Lubineau
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 …
Laser Metal Deposition Of An Alcocrfeniti₀.₅ High-Entropy Alloy Coating On A Ti6al4v Substrate: Microstructure And Oxidation Behavior, Wenyuan Cui, Wei Li, Wei Ting Chen, Frank W. Liou
Laser Metal Deposition Of An Alcocrfeniti₀.₅ High-Entropy Alloy Coating On A Ti6al4v Substrate: Microstructure And Oxidation Behavior, Wenyuan Cui, Wei Li, Wei Ting Chen, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Ti6Al4V has been recognized as an attractive material, due to its combination of low density and favorable mechanical properties. However, its insufficient oxidation resistance has limited the high-temperature application. In this work, an AlCoCrFeNiTi0.5 high-entropy alloy (HEA) coating was fabricated on a Ti6Al4V substrate using laser metal deposition (LMD). The microstructure and isothermal oxidation behaviors were investigated. The microstructure of as-deposited HEA exhibited a Fe, Cr-rich A2 phase and an Al, Ni, Ti-enriched B2 phase. Its hardness was approximately 2.1 times higher than that of the substrate. The oxidation testing at 700⁰C and 800⁰C suggested that the HEA coating …
A Review On Metallic Alloys Fabrication Using Elemental Powder Blends By Laser Powder Directed Energy Deposition Process, Yitao Chen, Xinchang Zhang, Mohammad Masud Parvez, Frank W. Liou
A Review On Metallic Alloys Fabrication Using Elemental Powder Blends By Laser Powder Directed Energy Deposition Process, Yitao Chen, Xinchang Zhang, Mohammad Masud Parvez, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The laser powder directed energy deposition process is a metal additive manufacturing technique, which can fabricate metal parts with high geometric and material flexibility. The unique feature of in-situ powder feeding makes it possible to customize the elemental composition using elemental powder mixture during the fabrication process. Thus, it can be potentially applied to synthesize industrial alloys with low cost, modify alloys with different powder mixtures, and design novel alloys with location-dependent properties using elemental powder blends as feedstocks. This paper provides an overview of using a laser powder directed energy deposition method to fabricate various types of alloys by …
Lateral Migration Of A Ferrofluid Droplet In A Plane Poiseuille Flow Under Uniform Magnetic Fields, Md Rifat Hassan, Cheng Wang
Lateral Migration Of A Ferrofluid Droplet In A Plane Poiseuille Flow Under Uniform Magnetic Fields, Md Rifat Hassan, Cheng Wang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The lateral migration of a two-dimensional (2D) viscous ferrofluid droplet in a plane Poiseuille flow under a uniform magnetic field is studied numerically by using the level set method. Focusing on low droplet Reynolds number flows (Red ≤ 0.05), several numerical simulations are carried out to analyze the effects of magnetic field direction and strength, droplet size, and viscosity ratio on the lateral migration behavior of the droplet. The results indicate that the magnetic field direction plays a pivotal role in the trajectory of lateral migration of the droplet and the final equilibrium position in the channel. When the …
On The Effect Of Interfacial Patterns On Energy Dissipation In Plastically Deforming Adhesive Bonded Ductile Sheets, Arturo Pascuzzo, Arief Yudhanto, Marco Alfano, Gilles Lubineau
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 …
Plasmon-Phonon Coupling Between Mid-Infrared Chiral Metasurfaces And Molecular Vibrations, Md Shamim Mahmud, Daniel Rosenmann, David A. Czaplewski, Jie Gao, Xiaodong Yang
Plasmon-Phonon Coupling Between Mid-Infrared Chiral Metasurfaces And Molecular Vibrations, Md Shamim Mahmud, Daniel Rosenmann, David A. Czaplewski, Jie Gao, Xiaodong Yang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Plasmon-phonon coupling between metamaterials and molecular vibrations provides a new path for studying mid-infrared light-matter interactions and molecular detection. So far, the coupling between the plasmonic resonances of metamaterials and the phonon vibrational modes of molecules has been realized under linearly polarized light. Here, mid-infrared chiral plasmonic metasurfaces with high circular dichroism (CD) in absorption over 0.65 in the frequency range of 50 to 60 THz are demonstrated to strongly interact with the phonon vibrational resonance of polymethyl methacrylate (PMMA) molecules at 52 THz, under both left-handed and right-handed circularly polarized (LCP and RCP) light. The mode splitting features in …
Determination Of Effective Parameters Of Fishnet Metamaterials With Vortex Based Interferometry, Wei Cao, Jie Gao, Xiaodong Yang
Determination Of Effective Parameters Of Fishnet Metamaterials With Vortex Based Interferometry, Wei Cao, Jie Gao, Xiaodong Yang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Metamaterials are artificially engineered structures that have unique properties not usually found in natural materials, such as negative refractive index. Conventional interferometry or ellipsometry is generally used for characterizing the optical properties of metamaterials. Here, we report an alternative optical vortex based interferometric approach for the characterization of the effective parameters of optical metamaterials by directly measuring the transmission and reflection phase shifts from metamaterials according to the rotation of vortex spiral interference pattern. The fishnet metamaterials possessing positive, zero and negative refractive indices are characterized with the vortex based interferometry to precisely determine the complex values of effective permittivity, …
Effects Of Zirconia Doping On Additively Manufactured Alumina Ceramics By Laser Direct Deposition, John M. Pappas, Aditya R. Thakur, Xiangyang Dong
Effects Of Zirconia Doping On Additively Manufactured Alumina Ceramics By Laser Direct Deposition, John M. Pappas, Aditya R. Thakur, Xiangyang Dong
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The ability to additively manufacture functional alumina ceramics has the potential to lower manufacturing costs and development time for complex components. In this study, the doping effects of zirconia on laser direct deposited alumina ceramics were investigated. The microstructure of the printed samples was analyzed in terms of grain size and composition distribution. The addition of zirconia was found to accumulate along alumina grain boundaries and resulted in significant grain refinement. The zirconia doping largely reduced crack formation during processing compared to that of pure alumina samples. In the case of 10 wt% zirconia, cracking during deposition was nearly completely …
Improving Mode Ii Fracture Toughness Of Secondary Bonded Joints Using Laser Patterning Of Adherends, A. Wagih, R. Tao, A. Yudhanto, G. Lubineau
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 …
How The Spatial Correlation In Adhesion Properties Influences The Performance Of Secondary Bonding Of Laminated Composites, Xiaole Li, Ran Tao, Arief Yudhanto, Gilles Lubineau
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 …
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
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 …
Numerical Study On The Temperature-Dependent Viscosity Effect On The Strand Shape In Extrusion-Based Additive Manufacturing, Behrouz Behdani, Matthew Senter, Leah Mason, Ming-Chuan Leu, Joontaek Park
Numerical Study On The Temperature-Dependent Viscosity Effect On The Strand Shape In Extrusion-Based Additive Manufacturing, Behrouz Behdani, Matthew Senter, Leah Mason, Ming-Chuan Leu, Joontaek Park
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A numerical model that incorporates temperature-dependent non-Newtonian viscosity was developed to simulate the extrusion process in extrusion-based additive manufacturing. Agreement with the experimental data was achieved by simulating a polylactic acid melt flow as a non-isothermal power law fluid using experimentally fitted parameters for polylactic acid. The model was used to investigate the temperature effect on the flow behavior, the cross-sectional area, and the uniformity of the extruded strand. OpenFOAM, an open source simulation tool based on the finite volume method, was used to perform the simulations. A computational module for solving the equations of non-isothermal multiphase flows was also …
Thermal Transport Across The Interface Between Liquid N-Dodecane And Its Own Vapor: A Molecular Dynamics Study, Eric Bird, Jesus Gutierrez Plascencia, Zhi Liang
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 …
Post-Impact Flexural Behavior Of Carbon-Aramid/Epoxy Hybrid Composites, A. Wagih, T. A. Sebaey, A. Yudhanto, G. Lubineau
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 …
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
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 …
Multifidelity Modeling By Polynomial Chaos-Based Cokriging To Enable Efficient Model-Based Reliability Analysis Of Ndt Systems, Xiaosong Du, Leifur Leifsson
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 …
A Molecular Dynamics Study Of Transient Evaporation And Condensation, Zhi Liang, Anirban Chandra, Eric Bird, Pawel Keblinski
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 …
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
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 …
Laser-Assisted Micromachining Systems And Methods, Yung C. Shin, Xiangyang Dong
Laser-Assisted Micromachining Systems And Methods, Yung C. Shin, Xiangyang Dong
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Laser-assisted micromachining methods and systems capable of providing flexible beam positioning and low incident angles. Such laser-assisted micromachining systems preferably include a laser beam source, a cutting tool, means for engaging a workpiece with the cutting tool, optical elements arranged to define a path of a laser beam emitted by the laser beam source wherein the optical elements include at least a first mirror mounted in fixed relation to the laser beam source, and means for adjustably mounting a second mirror to project the laser beam onto the workpiece in proximity to the cutting tool and at an incidence angle …
Angular Correlation Using Rogers-Szego-Chaos, Christine Schmid, Kyle J. Demars
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 …
Frequency-Selective Metasurface Integrated Uncooled Microbolometers, Mahmoud Almasri, Edward C. Kinzel
Frequency-Selective Metasurface Integrated Uncooled Microbolometers, Mahmoud Almasri, Edward C. Kinzel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A metasurface integrated microbolometer having a sensing layer (e.g., SixGeyO1-x-y). The presence of the metasurface provides selectivity with respect to wavelength, polarization and angle-of-incidence. The presence of the metasurface into the microbolometer affects conversion of electromagnetic to thermal energy, thermal response, electrical integration of the microbolometer, and the tradeoff between resistivity and temperature coefficient of resistance, thereby allowing the ability to obtain a sensing with high temperature coefficient of resistance with lower resistivity values than that of films without the metasurface. The presence of the metasurface removes the need for a Fabry-Perot cavity.
Aluminum Parts Fabricated By Laser-Foil-Printing Additive Manufacturing: Processing, Microstructure, And Mechanical Properties, Chia Hung Hung, Yingqi Li, Austin Sutton, Wei Ting Chen, Xiangtao Gong, Heng Pan, Hai Lung Tsai, Ming-Chuan Leu
Aluminum Parts Fabricated By Laser-Foil-Printing Additive Manufacturing: Processing, Microstructure, And Mechanical Properties, Chia Hung Hung, Yingqi Li, Austin Sutton, Wei Ting Chen, Xiangtao Gong, Heng Pan, Hai Lung Tsai, Ming-Chuan Leu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Fabrication of dense aluminum (Al-1100) parts (>99.3% of relative density) by our recently developed laser-foil-printing (LFP) additive manufacturing method was investigated as described in this paper. This was achieved by using a laser energy density of 7.0 MW/cm2 to stabilize the melt pool formation and create sufficient penetration depth with 300 μm thickness foil. The highest yield strength (YS) and ultimate tensile strength (UTS) in the LFP-fabricated samples reached 111 ± 8 MPa and 128 ± 3 MPa, respectively, along the laser scanning direction. These samples exhibited greater tensile strength but less ductility compared to annealed Al-1100 samples. Fractographic …
Metal Additive Manufacturing Parts Inspection Using Convolutional Neural Network, Wenyuan Cui, Yunlu Zhang, Xinchang Zhang, Lan Li, Frank W. Liou
Metal Additive Manufacturing Parts Inspection Using Convolutional Neural Network, Wenyuan Cui, Yunlu Zhang, Xinchang Zhang, Lan Li, Frank W. Liou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Metal additive manufacturing (AM) is gaining increasing attention from academia and industry due to its unique advantages compared to the traditional manufacturing process. Parts quality inspection is playing a crucial role in theAMindustry, which can be adopted for product improvement. However, the traditional inspection process has relied on manual recognition, which could suffer from low efficiency and potential bias. This study presented a convolutional neural network (CNN) approach toward robust AM quality inspection, such as good quality, crack, gas porosity, and lack of fusion. To obtain the appropriate model, experiments were performed on a series of architectures. Moreover, data augmentation …
Impartial Sensor Tasking Via Forecasted Information Content Quantification, Matthew J. Gualdoni, Kyle J. Demars
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 …
Optimization Strategies For Myopic And Forecasted Divergence-Based Sensor Tasking Objectives, Matthew J. Gualdoni, Kyle J. Demars
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 …
Impact Of Considering And Neglecting States On Descent-To-Landing Navigation, Kyle J. Demars, Kari C. Ward
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.
Robustness Metric For Robust Design Optimization Under Time-And Space-Dependent Uncertainty Through Metamodeling, Xinpeng Wei, Xiaoping Du
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 …
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
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 …