Open Access. Powered by Scholars. Published by Universities.®

Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Discipline
Keyword
Publication Year

Articles 331 - 360 of 1287

Full-Text Articles in Engineering

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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.

Go to article

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.

Go to article

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 …

Go to article

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 …

Go to article

Real-Time Assembly Operation Recognition With Fog Computing And Transfer Learning For Human-Centered Intelligent Manufacturing, Wenjin Tao, Md Al-Amin, Haodong Chen, Ming-Chuan Leu, Zhaozheng Yin, Ruwen Qin Jan 2020

Real-Time Assembly Operation Recognition With Fog Computing And Transfer Learning For Human-Centered Intelligent Manufacturing, Wenjin Tao, Md Al-Amin, Haodong Chen, Ming-Chuan Leu, Zhaozheng Yin, Ruwen Qin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In a human-centered intelligent manufacturing system, every element is to assist the operator in achieving the optimal operational performance. The primary task of developing such a human-centered system is to accurately understand human behavior. In this paper, we propose a fog computing framework for assembly operation recognition, which brings computing power close to the data source in order to achieve real-time recognition. For data collection, the operator's activity is captured using visual cameras from different perspectives. For operation recognition, instead of directly building and training a deep learning model from scratch, which needs a huge amount of data, transfer learning …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

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 …

Go to article

Bubble Pinch-Off In Turbulence, Daniel J. Ruth, Wouter Mostert, Stephane Perrard, Luc Deike Dec 2019

Bubble Pinch-Off In Turbulence, Daniel J. Ruth, Wouter Mostert, Stephane Perrard, Luc Deike

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Although bubble pinch-off is an archetype of a dynamical system evolving toward a singularity, it has always been described in idealized theoretical and experimental conditions. Here, we consider bubble pinch-off in a turbulent flow representative of natural conditions in the presence of strong and random perturbations, combining laboratory experiments, numerical simulations, and theoretical modeling. We show that the turbulence sets the initial conditions for pinch-off, namely the initial bubble shape and flow field, but after the pinch-off starts, the turbulent time at the neck scale becomes much slower than the pinching dynamics: The turbulence freezes. We show that the average …

Go to article

Generation Of Polarization Singularities With Geometric Metasurfaces, Yuchao Zhang, Xiaodong Yang, Jie Gao Dec 2019

Generation Of Polarization Singularities With Geometric Metasurfaces, Yuchao Zhang, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The polarization singularities are directly generated by using plasmonic metasurfaces with the geometric phase profiles designed to form the Poincaré beams. Different morphologies of polarization topological structures of lemon, star, monstar, spiral, dipole and quadrupole are created by the superpositions of Laguerre-Gauss modes with different orders under orthogonal circular or linear polarization basis. The polarization ellipse patterns and topological features of the produced optical vector fields are analyzed to reveal the properties of the polarization singularities of C-points and L-lines, and the orbital angular momentum states are also measured. The demonstrated polarization singularities generated from the geometric metasurfaces will promise …

Go to article

Droplets As Carriers For Flexible Electronic Devices, Mingxing Zhou, Ziyue Wu, Yicong Zhao, Qing Yang, Wei Ling, Ya Li, Hang Xu, Cheng Wang, Xian Huang Dec 2019

Droplets As Carriers For Flexible Electronic Devices, Mingxing Zhou, Ziyue Wu, Yicong Zhao, Qing Yang, Wei Ling, Ya Li, Hang Xu, Cheng Wang, Xian Huang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Coupling soft bodies and dynamic motions with multifunctional flexible electronics is challenging, but is essential in satisfying the urgent and soaring demands of fully soft and comprehensive robotic systems that can perform tasks in spite of rigorous spatial constraints. Here, the mobility and adaptability of liquid droplets with the functionality of flexible electronics, and techniques to use droplets as carriers for flexible devices are combined. The resulting active droplets (ADs) with volumes ranging from 150 to 600 µL can conduct programmable functions, such as sensing, actuation, and energy harvesting defined by the carried flexible devices and move under the excitation …

Go to article

3d Janus Plasmonic Helical Nanoapertures For Polarization-Encrypted Data Storage, Yang Chen, Xiaodong Yang, Jie Gao Dec 2019

3d Janus Plasmonic Helical Nanoapertures For Polarization-Encrypted Data Storage, Yang Chen, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Helical structures have attracted considerable attention due to their inherent optical chirality. Here, we report a unique type of 3D Janus plasmonic helical nanoaperture with direction-controlled polarization sensitivity, which is simply fabricated via the one-step grayscale focused ion beam milling method. Circular dichroism in transmission of as large as 0.72 is experimentally realized in the forward direction due to the spin-dependent mode coupling process inside the helical nanoaperture. However, in the backward direction, the nanoaperture acquires giant linear dichroism in transmission of up to 0.87. By encoding the Janus metasurface with the two nanoaperture enantiomers having specified rotation angles, direction-controlled …

Go to article

Orbital Angular Momentum Transformation Of Optical Vortex With Aluminum Metasurfaces, Yuchao Zhang, Xiaodong Yang, Jie Gao Dec 2019

Orbital Angular Momentum Transformation Of Optical Vortex With Aluminum Metasurfaces, Yuchao Zhang, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The orbital angular momentum (OAM) transformation of optical vortex is realized upon using aluminum metasurfaces with phase distributions derived from the caustic theory. The generated OAM transformation beam has the well-defined Bessel-like patterns with multiple designed topological charges from -1 to +2.5 including both the integer-order and fractional-order optical vortices along the propagation. The detailed OAM transformation process is observed in terms of the variations of both beam intensity and phase profiles. The dynamic distributions of OAM mode density in the transformation are further analyzed to illustrate the conservation of the total OAM. The demonstration of transforming OAM states arbitrarily …

Go to article

Pore Elimination Mechanisms During 3d Printing Of Metals, S. Mohammad H. Hojjatzadeh, Niranjan D. Parab, Wentao Yan, Lianyi Chen, For Full List Of Authors, See Publisher's Website. Dec 2019

Pore Elimination Mechanisms During 3d Printing Of Metals, S. Mohammad H. Hojjatzadeh, Niranjan D. Parab, Wentao Yan, Lianyi Chen, For Full List Of Authors, See Publisher's Website.

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laser powder bed fusion (LPBF) is a 3D printing technology that can print metal parts with complex geometries without the design constraints of traditional manufacturing routes. However, the parts printed by LPBF normally contain many more pores than those made by conventional methods, which severely deteriorates their properties. Here, by combining in-situ high-speed high-resolution synchrotron x-ray imaging experiments and multi-physics modeling, we unveil the dynamics and mechanisms of pore motion and elimination in the LPBF process. We find that the high thermocapillary force, induced by the high temperature gradient in the laser interaction region, can rapidly eliminate pores from the …

Go to article

Spatial Variation Of Vector Vortex Beams With Plasmonic Metasurfaces, Yuchao Zhang, Jie Gao, Xiaodong Yang Dec 2019

Spatial Variation Of Vector Vortex Beams With Plasmonic Metasurfaces, Yuchao Zhang, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The spatial variation of vector vortex beams with arbitrary polarization states and orbital angular momentum (OAM) values along the beam propagation is demonstrated by using plasmonic metasurfaces with the initial geometric phase profiles determined from the caustic theory. The vector vortex beam is produced by the superposition of deflected right- and left-handed circularly polarized component vortices with different helical phase charges, which are simultaneously generated off-axially by the single metasurface. Besides, the detailed evolution processes of intensity profile, polarization distribution and OAM value along the beam propagation distance is analyzed. The demonstrated arbitrary space-variant vector vortex beam will pave the …

Go to article

Spontaneous Emission Rate Enhancement With Aperiodic Thue-Morse Multilayer, Ling Li, Cherian J. Mathai, Shubhra Gangopadhyay, Xiaodong Yang, Jie Gao Dec 2019

Spontaneous Emission Rate Enhancement With Aperiodic Thue-Morse Multilayer, Ling Li, Cherian J. Mathai, Shubhra Gangopadhyay, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The emergence of multilayer metamaterials in the research field of enhancing spontaneous emission rates has recently received extensive attention. Previous research efforts mostly focus on periodic metal-dielectric multilayers in hyperbolic dispersion region; however, the influence of lattice order in subwavelength multilayers on spontaneous emission is rarely studied. Here, we observe the stronger Purcell enhancement of quantum dots coupled to the aperiodic metal-dielectric multilayer with Thue-Morse lattice order from elliptical to hyperbolic dispersion regions, compared to the periodic multilayer with the same metal filling ratio. This work demonstrates the potential of utilizing quasiperiodic metamaterial nanostructures to engineer the local density of …

Go to article

Publisher Correction: Pore Elimination Mechanisms During 3d Printing Of Metals (Nature Communications, (2019), 10, 1, (3088), 10.1038/S41467-019-10973-9), S. Mohammad H. Hojjatzadeh, Niranjan D. Parab, Wentao Yan, Qilin Guo, Lianghua Xiong, Cang Zhao, Mimglei Qu, Luis I. Escano, Xianghui Xiao, Kamel Fezzaa, Wes Everhart, Tao Sun, Lianyi Chen Dec 2019

Publisher Correction: Pore Elimination Mechanisms During 3d Printing Of Metals (Nature Communications, (2019), 10, 1, (3088), 10.1038/S41467-019-10973-9), S. Mohammad H. Hojjatzadeh, Niranjan D. Parab, Wentao Yan, Qilin Guo, Lianghua Xiong, Cang Zhao, Mimglei Qu, Luis I. Escano, Xianghui Xiao, Kamel Fezzaa, Wes Everhart, Tao Sun, Lianyi Chen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The original version of this Article contained an error in Fig. 4. The x-axis labels in Fig. 4a, b were incorrectly labelled 'Diameter (mm)', rather than the correct 'Diameter (µm)'. This has been corrected in both the PDF and HTML versions of the Article.

Go to article

Second-Harmonic Optical Vortex Conversion From Ws₂ Monolayer, Arindam Dasgupta, Jie Gao, Xiaodong Yang Dec 2019

Second-Harmonic Optical Vortex Conversion From Ws₂ Monolayer, Arindam Dasgupta, Jie Gao, Xiaodong Yang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Wavelength, polarization and orbital angular momentum of light are important degrees of freedom for processing and encoding information in optical communication. Over the years, the generation and conversion of orbital angular momentum in nonlinear optical media has found many novel applications in the context of optical communication and quantum information processing. With that hindsight, here orbital angular momentum conversion of optical vortices through second-harmonic generation from only one atomically thin WS2 monolayer is demonstrated at room temperature. Moreover, it is shown that the valley-contrasting physics associated with the nonlinear optical selection rule in WS2 monolayer precisely determines the output circular …

Go to article

Magnetic Field Induced Ferrofluid Droplet Breakup In A Simple Shear Flow At A Low Reynolds Number, Md Rifat Hassan, Cheng Wang Dec 2019

Magnetic Field Induced Ferrofluid Droplet Breakup In A Simple Shear Flow At A Low Reynolds Number, Md Rifat Hassan, Cheng Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The breakup phenomenon of a ferrofluid droplet in a simple shear flow under a uniform magnetic field is numerically investigated in this paper. The numerical simulation, based on the finite element method, uses a level set method to capture the dynamic evolution of the droplet interface between the two phases. Focusing on small Reynolds numbers (i.e., Re ≤ 0.03), systematic numerical simulations are carried out to analyze the effects of magnetic field strength, direction, and viscosity ratio on the breakup phenomenon of the ferrofluid droplet. The results suggest that applying a magnetic field along α = 45° and 90° relative …

Go to article

Transport Phenomena In The Knudsen Layer Near An Evaporating Surface, Eric Bird, Zhi Liang Oct 2019

Transport Phenomena In The Knudsen Layer Near An Evaporating Surface, Eric Bird, Zhi Liang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the Combination of the Kinetic Theory of Gases (KTG), Boltzmann Transport Equation (BTE), and Molecular Dynamics (MD) Simulations, We Study the Transport Phenomena in the Knudsen Layer Near a Planar Evaporating Surface. the MD Simulation is First Used to Validate the Assumption Regarding the Anisotropic Velocity Distribution of Vapor Molecules in the Knudsen Layer. based on This Assumption, We Use the KTG to Formulate the Temperature and Density of Vapor at the Evaporating Surface as a Function of the Evaporation Rate and the Mass Accommodation Coefficient (MAC), and We Use These Vapor Properties as the Boundary Conditions to Find …

Go to article

A Study Of Brain Neuronal And Functional Complexities Estimated Using Multiscale Entropy In Healthy Young Adults, Sreevalsan S. Menon, K. Krishnamurthy Oct 2019

A Study Of Brain Neuronal And Functional Complexities Estimated Using Multiscale Entropy In Healthy Young Adults, Sreevalsan S. Menon, K. Krishnamurthy

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Brain complexity estimated using sample entropy and multiscale entropy (MSE) has recently gained much attention to compare brain function between diseased or neurologically impaired groups and healthy control groups. Using resting-state functional magnetic resonance imaging (rfMRI) blood oxygen-level dependent (BOLD) signals in a large cohort (n = 967) of healthy young adults, the present study maps neuronal and functional complexities estimated by using MSE of BOLD signals and BOLD phase coherence connectivity, respectively, at various levels of the brain’s organization. The functional complexity explores patterns in a higher dimension than neuronal complexity and may better discern changes in brain functioning. …

Go to article

Strong Circular Dichroism In Chiral Plasmonic Metasurfaces Optimized By Micro-Genetic Algorithm, Zhigang Li, Daniel Rosenmann, David A. Czaplewski, Xiaodong Yang, Jie Gao Sep 2019

Strong Circular Dichroism In Chiral Plasmonic Metasurfaces Optimized By Micro-Genetic Algorithm, Zhigang Li, Daniel Rosenmann, David A. Czaplewski, Xiaodong Yang, Jie Gao

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Strong circular dichroism in absorption in the near-infrared wavelength range is realized by designing binary-pattern chiral plasmonic metasurfaces via the micro-genetic algorithm optimization method. The influence of geometric parameter modifications in the binary-pattern nanostructures on the circular dichroism performance is studied. The strong circular dichroism in absorption is attributed to the simultaneous excitation and field interference of the resonant modes with relative phase delay under linearly polarized incident light. This work provides a universal design method toward the on-demand properties of chiral metasurfaces, which paves the way for future applications in chemical and biological sensing, chiral imaging and spectroscopy.

Go to article

Reliability-Based Design Optimization Of Load Sharing Systems Using Ssi-Markov Models, Arun Bala Subramaniyan, Rong Pan, Xiaoping Du Sep 2019

Reliability-Based Design Optimization Of Load Sharing Systems Using Ssi-Markov Models, Arun Bala Subramaniyan, Rong Pan, Xiaoping Du

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a novel single loop approach to design the components of the load sharing systems by optimally allocating the failure probabilities to each component, thereby satisfying the overall system reliability requirement. The Reliability–Based Design Optimization (RBDO) of load sharing systems is computationally intensive due to the dynamic nature of component failure probabilities, since the failure of one component will vary the failure probabilities of other working components. Many RBDO methods have been successfully utilized to design individual components, however using these methods for handling system level reliability constraints is still a challenging task. This is because of a …

Go to article

Frequency Inspection Of Additively Manufactured Parts For Layer Defect Identification, Aimee Allen, Kevin Johnson, Jason R. Blough, Andrew Barnard, Troy Hartwig, Ben Brown, David Soine, Tristan Cullom, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel Aug 2019

Frequency Inspection Of Additively Manufactured Parts For Layer Defect Identification, Aimee Allen, Kevin Johnson, Jason R. Blough, Andrew Barnard, Troy Hartwig, Ben Brown, David Soine, Tristan Cullom, Douglas A. Bristow, Robert G. Landers, Edward C. Kinzel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Additive manufactured (AM) parts are produced at low volume or with complex geometries. Identifying internal defects is difficult as current testing techniques are not optimized for AM processes. The goal of this paper is to evaluate defects on multiple parts printed on the same build plate. The technique used was resonant frequency testing with the results verified through Finite Element Analysis. From these tests, it was found that the natural frequencies needed to detect the defects were higher than the excitation provided by a modal hammer. The deficiencies in this range led to the development of other excitation methods. Based …

Go to article

First Prev Next Last