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Selected Works

2018

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Articles 1 - 30 of 93

Full-Text Articles in Mechanical Engineering

Robust State Dependent Riccati Equation Based Robot Manipulator Control, Ming Xin, S. N. Balakrishnan, Zhongwu Huang Dec 2018

Robust State Dependent Riccati Equation Based Robot Manipulator Control, Ming Xin, S. N. Balakrishnan, Zhongwu Huang

S. N. Balakrishnan

We present a new optimal control approach to robust control of robot manipulators in the framework of state dependent Riccati equation (SDRE) technique. To treat this highly nonlinear control system, we formulate it as a nonlinear optimal regulator problem. SDRE technique was used to synthesize an optimal controller to this class of robot control problem. We also synthesize a neural network based extra controller to achieve the robustness in the presence of the parameter uncertainties. A typical two-link robot position control problem was studied to show the effectiveness of SDRE approach and robust extra control design to robotic application.


Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha Dec 2018

Dynamic Re-Optimization Of A Mems Controller In Presence Of Unmodeled Uncertainties, Nishant Unnikrishnan, S. N. Balakrishnan, Venkat Durbha

S. N. Balakrishnan

Online trained neural networks have become popular in recent years in designing robust and adaptive controllers for dynamic systems with uncertainties in their system equations because of their universal function approximation property. This paper discusses a technique that dynamically reoptimizes a Single Network Adaptive Critic (SNAC) based optimal controller in the presence of unmodeled uncertainties. The controller design is carried out in two steps: (i) synthesis of a set of online neural networks that capture the uncertainties in the plant equations on-line (ii) re-optimization of the existing optimal controller to drive the states of the plant to a desired reference ...


Solid State Aircraft Concept Overview, M. Shahinpoor, P. Jenkins, C. Smith, Kakkattukuzhy M. Isaac, T. Dalbello, Anthony Colozza Dec 2018

Solid State Aircraft Concept Overview, M. Shahinpoor, P. Jenkins, C. Smith, Kakkattukuzhy M. Isaac, T. Dalbello, Anthony Colozza

Kakkattukuzhy Isaac

Due to recent advances in polymers, photovoltaics, and batteries a unique type of aircraft may be feasible. This is a "solid-state" aircraft, with no conventional mechanical moving parts. Airfoil, propulsion, energy production, energy storage and control are combined in an integrated structure. The key material of this concept is an ionic polymeric-metal composite (IPMC) that provides source of control and propulsion. This material has the unique capability of deforming in an electric field and returning to its original shape when the field is removed. Combining the IPMC with thin-film batteries and thin-film photovoltaics provides both energy source and storage in ...


Intelligent Strain Sensing On A Smart Composite Wing Using Extrinsic Fabry-Perot Interferometric Sensors And Neural Networks, Kakkattukuzhy M. Isaac, Donald C. Wunsch, Steve Eugene Watkins, Rohit Dua, V. M. Eller Dec 2018

Intelligent Strain Sensing On A Smart Composite Wing Using Extrinsic Fabry-Perot Interferometric Sensors And Neural Networks, Kakkattukuzhy M. Isaac, Donald C. Wunsch, Steve Eugene Watkins, Rohit Dua, V. M. Eller

Kakkattukuzhy Isaac

Strain prediction at various locations on a smart composite wing can provide useful information on its aerodynamic condition. The smart wing consisted of a glass/epoxy composite beam with three extrinsic Fabry-Perot interferometric (EFPI) sensors mounted at three different locations near the wing root. Strain acting on the three sensors at different air speeds and angles-of-attack were experimentally obtained in a closed circuit wind tunnel under normal conditions of operation. A function mapping the angle of attack and air speed to the strains on the three sensors was simulated using feedforward neural networks trained using a backpropagation training algorithm. This ...


Plastic Fiber Rolling For Concrete Reinforcement, Jeffery S. Thomas Dec 2018

Plastic Fiber Rolling For Concrete Reinforcement, Jeffery S. Thomas

Jeffery S. Thomas

"Fiber reinforced concrete is gaining in acceptance and usage as its strength and toughness benefits are realized. Polypropylene fibers are currently the most commonly used fibers. However, the cost of virgin plastics limits the percent content that can be economically added to concrete. One would first believe that recycled plastics could offer a viable alternative to virgin-plastic fibers, but at present time extra selection and cleaning steps required to reprocess the recycled plastic into fibers makes it more expensive than virgin-plastic fibers. A fiber rolling process conceived and developed at the University of Missouri-Rolla has the potential of making recycled ...


Phase Resolved Near-Field Mode Imaging For The Design Of Frequency-Selective Surfaces, Edward C. Kinzel, J. C. Ginn, R. L. Olmon, D. J. Shelton, B. A. Lail, I. Brenner, M. B. Sinclair, M. B. Raschke, G. D. Boreman Dec 2018

Phase Resolved Near-Field Mode Imaging For The Design Of Frequency-Selective Surfaces, Edward C. Kinzel, J. C. Ginn, R. L. Olmon, D. J. Shelton, B. A. Lail, I. Brenner, M. B. Sinclair, M. B. Raschke, G. D. Boreman

Edward C. Kinzel

No abstract provided.


Directional Thermal Emission From A Leaky-Wave Frequency-Selective Surface, Edward C. Kinzel, J. C. Ginn, L. A. Florence, B. A. Lail, G. D. Boreman Dec 2018

Directional Thermal Emission From A Leaky-Wave Frequency-Selective Surface, Edward C. Kinzel, J. C. Ginn, L. A. Florence, B. A. Lail, G. D. Boreman

Edward C. Kinzel

No abstract provided.


Fluoride-Induced Dynamic Surface Self-Reconstruction Produces Unexpectedly Efficient Oxygen-Evolution Catalyst, Bowei Zhang, Kun Jiang, Haotian Wang, Shan Hu Dec 2018

Fluoride-Induced Dynamic Surface Self-Reconstruction Produces Unexpectedly Efficient Oxygen-Evolution Catalyst, Bowei Zhang, Kun Jiang, Haotian Wang, Shan Hu

Shan Hu

The oxygen-evolution reaction (OER) is a key process in water-splitting systems, fuel cells, and metal–air batteries, but the development of highly active and robust OER catalyst by simple methods is a great challenge. Here, we report an in situ dynamic surface self-reconstruction that can dramatically improve the catalytic activity of electrocatalysts. A fluoride (F)-incorporating NiFe hydroxide (NiFe-OH-F) nanosheet array was initially grown on Ni foam by a one-step hydrothermal method, which requires a 243 mV over-potential (η) to achieve a 10 mA cm–2 current density with a Tafel slope of 42.9 mV dec–1 in alkaline ...


Structural Responses Of Metallic Glasses Under Neutron Irradiation, L. Yang, H. Y. Li, P. W. Wang, S. Wu, G. Guo, B. Liao, Q. L. Guo, X. Q. Fan, P. Huang, H. B. Lou, F. M. Guo, Q. Zeng, T. Sun, Y. Ren, Lianyi Chen Dec 2018

Structural Responses Of Metallic Glasses Under Neutron Irradiation, L. Yang, H. Y. Li, P. W. Wang, S. Wu, G. Guo, B. Liao, Q. L. Guo, X. Q. Fan, P. Huang, H. B. Lou, F. M. Guo, Q. Zeng, T. Sun, Y. Ren, Lianyi Chen

Lianyi Chen

No abstract provided.


Real-Time Monitoring Of Laser Powder Bed Fusion Process Using High-Speed X-Ray Imaging And Diffraction, C. Zhao, K. Fezzaa, R. W. Cunningham, H. Wen, F. De Carlo, Lianyi Chen, A. D. Rollett, T. Sun Dec 2018

Real-Time Monitoring Of Laser Powder Bed Fusion Process Using High-Speed X-Ray Imaging And Diffraction, C. Zhao, K. Fezzaa, R. W. Cunningham, H. Wen, F. De Carlo, Lianyi Chen, A. D. Rollett, T. Sun

Lianyi Chen

No abstract provided.


Nanoparticle-Induced Unusual Melting And Solidification Behaviours Of Metals, C. Ma, Lianyi Chen, C. Cao, X.C. Li Dec 2018

Nanoparticle-Induced Unusual Melting And Solidification Behaviours Of Metals, C. Ma, Lianyi Chen, C. Cao, X.C. Li

Lianyi Chen

No abstract provided.


The Child Brain Computes And Utilizes Internalized Maternal Choices, S. Seung-Lark Lim, J. Cherry C. Bradley, A. Davis, S. N. Balakrishnan, O. Ha, J. Bruce, A. Bruce Dec 2018

The Child Brain Computes And Utilizes Internalized Maternal Choices, S. Seung-Lark Lim, J. Cherry C. Bradley, A. Davis, S. N. Balakrishnan, O. Ha, J. Bruce, A. Bruce

S. N. Balakrishnan

No abstract provided.


Weighting Matrix Design For Robust Monotonic Convergence In Norm Optimal Iterative Learning Control, Douglas A. Bristow Dec 2018

Weighting Matrix Design For Robust Monotonic Convergence In Norm Optimal Iterative Learning Control, Douglas A. Bristow

Douglas Bristow

In this paper we examine the robustness of norm optimal ILC with quadratic cost criterion for discrete-time, linear time-invariant, single-input single-output systems. A bounded multiplicative uncertainty model is used to describe the uncertain system and a sufficient condition for robust monotonic convergence is developed. We find that, for sufficiently large uncertainty, the performance weighting can not be selected arbitrarily large, and thus overall performance is limited. To maximize available performance, a time-frequency design methodology is presented to shape the weighting matrix based on the initial tracking error. The design is applied to a nanopositioning system and simulation results are presented.


Quasistatic Error Modeling And Model Testing For A 5-Axis Machine, H-W. Ko, P. Bazzoli, Jared Adam Nisbett, L. Ma, Douglas A. Bristow, Robert G. Landers, Y. Chen, S. Kapoor, P. F. Ferreira Dec 2018

Quasistatic Error Modeling And Model Testing For A 5-Axis Machine, H-W. Ko, P. Bazzoli, Jared Adam Nisbett, L. Ma, Douglas A. Bristow, Robert G. Landers, Y. Chen, S. Kapoor, P. F. Ferreira

Douglas Bristow

No abstract provided.


Monotonic Convergence Of Iterative Learning Control For Uncertain Systems Using A Time-Varying Filter, Douglas A. Bristow, Andrew G. Alleyne Dec 2018

Monotonic Convergence Of Iterative Learning Control For Uncertain Systems Using A Time-Varying Filter, Douglas A. Bristow, Andrew G. Alleyne

Douglas Bristow

Iterative learning control (ILC) is a learning technique used to improve the performance of systems that execute the same task multiple times. Learning transient behavior has emerged as an important topic in the design and analysis of ILC systems. In practice, the learning control is often low-pass filtered with a ldquoQ-filterrdquo to prevent transient growth, at the cost of performance. In this note, we consider linear time-invariant, discrete-time, single-input single-output systems, and convert frequency-domain uncertainty models to a time-domain representation for analysis. We then develop robust monotonic convergence conditions, which depend directly on the choice of the Q-filter and are ...


High Bandwidth Control Of Precision Motion Instrumentation, Douglas A. Bristow, Jingyan Dong, Andrew G. Alleyne, Srinivasa M. Salapaka, Placid M. Ferreira Dec 2018

High Bandwidth Control Of Precision Motion Instrumentation, Douglas A. Bristow, Jingyan Dong, Andrew G. Alleyne, Srinivasa M. Salapaka, Placid M. Ferreira

Douglas Bristow

This article presents a high-bandwidth control design suitable for precision motion instrumentation. Iterative learning control (ILC), a feedforward technique that uses previous iterations of the desired trajectory, is used to leverage the repetition that occurs in many tasks, such as raster scanning in microscopy. Two ILC designs are presented. The first design uses the motion system dynamic model to maximize bandwidth. The second design uses a time-varying bandwidth that is particularly useful for nonsmooth trajectories such as raster scanning. Both designs are applied to a multiaxis piezoelectric-actuated flexure system and evaluated on a nonsmooth trajectory. The ILC designs demonstrate significant ...


Frequency Domain Analysis And Design Of Iterative Learning Control For Systems With Stochastic Disturbances, Douglas A. Bristow Dec 2018

Frequency Domain Analysis And Design Of Iterative Learning Control For Systems With Stochastic Disturbances, Douglas A. Bristow

Douglas Bristow

In this work we examine the performance of iterative learning control (ILC) for systems with non-repeating disturbances and random noise. Single-input, single- output linear time-invariant systems and iteration-invariant learning filters are considered. We find that a tradeoff exists between the convergence rate and converged error spectrum. Optimal filter designs, which are dependant on the disturbance and noise spectra, are developed. We also present simple design guidelines for the case when explicit models of disturbance and noise spectra are not available. A numerical design example is presented.


Design Of A Linear Time-Varying Cross-Coupled Iterative Learning Controller, K. L. Barton, Douglas A. Bristow, Andrew G. Alleyne Dec 2018

Design Of A Linear Time-Varying Cross-Coupled Iterative Learning Controller, K. L. Barton, Douglas A. Bristow, Andrew G. Alleyne

Douglas Bristow

In many manufacturing applications contour tracking is more important than individual axis tracking. Many control techniques, including iterative learning control (ILC), target individual axis error. Because individual axis error only indirectly relates to contour error, these approaches may not be very effective for contouring applications. Cross-coupled ILC (CCILC) is a variation on traditional ILC that targets the contour tracking directly. In contour trajectories with rapid changes, high frequency control is necessary in order to meet tracking requirements. This paper presents an improved CCILC that uses a linear time-varying (LTV) filter to provide high frequency control for short durations. The improved ...


Combined H∞-Feedback Control And Iterative Learning Control Design With Application To Nanopositioning Systems, Brian E. Helfrich, Chibum Lee, Douglas A. Bristow, Jingyan Dong, Srinivasa M. Salapaka, Placid M. Ferreira, X. H. Xiao, Andrew G. Alleyne Dec 2018

Combined H∞-Feedback Control And Iterative Learning Control Design With Application To Nanopositioning Systems, Brian E. Helfrich, Chibum Lee, Douglas A. Bristow, Jingyan Dong, Srinivasa M. Salapaka, Placid M. Ferreira, X. H. Xiao, Andrew G. Alleyne

Douglas Bristow

This paper examines a coordinated feedback and feedforward control design strategy for precision motion control (PMC) systems. It is assumed that the primary exogenous signals are repeated; including disturbances and references. Therefore, an iterative learning control (ILC) feedforward strategy can be used. The introduction of additional non-repeating exogenous signals, including disturbances, noise, and reset errors, necessitates the proper coordination between feedback and feedforward controllers to achieve high performance. A novel ratio of repeated versus non-repeated signal power in the frequency domain is introduced and defined as the repetitive-to-non-repetitive (RNR) ratio. This frequency specific ratio allows for a new approach to ...


Bi-Harmonic Cantilever Design For Improved Measurement Sensitivity In Tapping-Mode Atomic Force Microscopy, M. Loganathan, Douglas A. Bristow Dec 2018

Bi-Harmonic Cantilever Design For Improved Measurement Sensitivity In Tapping-Mode Atomic Force Microscopy, M. Loganathan, Douglas A. Bristow

Douglas Bristow

No abstract provided.


Effects Of Local Ph On The Formation And Regulation Of Cristae Morphologies, Dong Hoon Song, Jonghyun Park, Martin A. Philbert, Ann Marie Sastry, Wei Lu Nov 2018

Effects Of Local Ph On The Formation And Regulation Of Cristae Morphologies, Dong Hoon Song, Jonghyun Park, Martin A. Philbert, Ann Marie Sastry, Wei Lu

Jonghyun Park

Cristae, folded subcompartments of the inner mitochondrial membrane (IMM), have complex and dynamic morphologies. Since cristae are the major site of adenosine triphosphate synthesis, morphological changes of cristae have been studied in relation to functional states of mitochondria. In this sense, investigating the functional and structural significance of cristae may be critical for understanding progressive mitochondrial dysfunction. However, the detailed mechanisms of the formation and regulation of these cristae structures have not been fully elucidated. Among the hypotheses concerning the regulation of cristae morphologies, we exclusively investigate the effects of the local pH gradient on the cristae morphologies by using ...


Synthesis Of Graphene Nanosheets Through Spontaneous Sodiation Process, Deepak-George Thomas, Emrah Kavak, Niloofar Hashemi, Reza Montazami, Nicole N. Hashemi Nov 2018

Synthesis Of Graphene Nanosheets Through Spontaneous Sodiation Process, Deepak-George Thomas, Emrah Kavak, Niloofar Hashemi, Reza Montazami, Nicole N. Hashemi

Nicole N. Hashemi

Graphene is one of the emerging materials in the nanotechnology industry due to its potential applications in diverse areas. We report the fabrication of graphene nanosheets by spontaneous electrochemical reaction using solvated ion intercalation into graphite. The current literature focuses on the fabrication of graphene using lithium metal. Our procedure uses sodium metal, which results in a reduction of costs. Using various characterization techniques, we confirmed the fabrication of graphene nanosheets. We obtained an intensity ratio (ID/IG) of 0.32 using Raman spectroscopy, interlayer spacing of 0.39 nm and our XPS results indicate that our fabricated compound is ...


On-Chip Development Of Hydrogel Microfibers From Round To Square/Ribbon Shape, Zhenhua Bai, Janet M. Mendoza Reyes, Reza Montazami, Nicole Nastaran Hashemi Nov 2018

On-Chip Development Of Hydrogel Microfibers From Round To Square/Ribbon Shape, Zhenhua Bai, Janet M. Mendoza Reyes, Reza Montazami, Nicole Nastaran Hashemi

Nicole N. Hashemi

We use a microfluidic approach to fabricate gelatin fibers with controlled sizes and cross-sections. Uniform gelatin microfibers with various morphologies and cross-sections (round and square) are fabricated by increasing the gelatin concentration of the core solution from 8% to 12%. Moreover, the increase of gelatin concentration greatly improves the mechanical properties of gelatin fibers; the Young's modulus and tensile stress at break of gelatin (12%) fibers are raised about 2.2 and 1.9 times as those of gelatin (8%) fibers. The COMSOL simulations indicate that the sizes and cross-sections of the gelatin fibers can be tuned by using ...


Dynamic Fracture At An Interface: A Peridynamic Analysis, Javad Mehrmashhadi, Longzhen Wang, Quang Van Le, Florin Bobaru Ph.D. Nov 2018

Dynamic Fracture At An Interface: A Peridynamic Analysis, Javad Mehrmashhadi, Longzhen Wang, Quang Van Le, Florin Bobaru Ph.D.

Javad Mehrmashhadi

Recent impact experiments showed the influence a strong or weak interface in a bi-layered PMMA material has on dynamic fracture mechanisms. We show that a linear elastic with brittle damage peridynamic model, which works very well for glass, leads to crack propagation speeds significantly faster than those measured experimentally in the PMMA system. We propose an explanation for this behavior: localized heating in the region near the crack tip (due to high strain rates) softens the material sufficiently to make a difference. We introduce this effect in our peridynamic model, via a bi-linear bond force-strain relationship, and the computed crack ...


Dynamic Fracture Of Pmma, Intefacial Failure, And Local Heating, Javad Mehrmashhadi, Longzhen Wang, Florin Bobaru Ph.D. Nov 2018

Dynamic Fracture Of Pmma, Intefacial Failure, And Local Heating, Javad Mehrmashhadi, Longzhen Wang, Florin Bobaru Ph.D.

Javad Mehrmashhadi

Recent impact experiments showed the influence of a strong or weak interface in a bi-layered PMMA material has on dynamic fracture mechanisms. We show that a linear elastic with brittle damage peridynamic model, which works very well for glass, leads to crack propagation speeds significantly faster than those measured experimentally in the PMMA system. We propose an explanation for this behavior: localized heating in the region near the crack tip (due to high strain rates) softens the material sufficiently to make a difference. We introduce this effect in our peridynamic model, via a bi-linear bond force-strain relationship, and the computed ...


Shape-Based Separation Of Micro-/Nanoparticles In Liquid Phases, Behrouz Behdani, Saman Monjezi, Mason J. Carey, Curtis G. Weldon, Jie Zhang, Cheng Wang, Joontaek Park Nov 2018

Shape-Based Separation Of Micro-/Nanoparticles In Liquid Phases, Behrouz Behdani, Saman Monjezi, Mason J. Carey, Curtis G. Weldon, Jie Zhang, Cheng Wang, Joontaek Park

Joontaek Park

The production of particles with shape-specific properties is reliant upon the separation of micro-/nanoparticles of particular shapes from particle mixtures of similar volumes. However, compared to a large number of size-based particle separation methods, shape-based separation methods have not been adequately explored. We review various up-to-date approaches to shape-based separation of rigid micro-/nanoparticles in liquid phases including size exclusion chromatography, field flow fractionation, deterministic lateral displacement, inertial focusing, electrophoresis, magnetophoresis, self-assembly precipitation, and centrifugation. We discuss separation mechanisms by classifying them as either changes in surface interactions or extensions of size-based separation. The latter includes geometric restrictions and ...


Flexible Laser-Induced Graphene For Nitrogen Sensing In Soil, Nate T. Garland, Eric S. Mclamore, Nicholas D. Cavallaro, Deyny Mendivelso-Perez, Emily A. Smith, Dapeng Jing, Jonathan C. Claussen Oct 2018

Flexible Laser-Induced Graphene For Nitrogen Sensing In Soil, Nate T. Garland, Eric S. Mclamore, Nicholas D. Cavallaro, Deyny Mendivelso-Perez, Emily A. Smith, Dapeng Jing, Jonathan C. Claussen

Jonathan C. Claussen

Flexible graphene electronics are rapidly gaining interest, but their widespread implementation has been impeded by challenges with ink preparation, ink printing, and post-print annealing processes. Laser-induced graphene (LIG) promises a facile alternative by creating flexible graphene electronics on polyimide substrates through a one-step laser writing fabrication method. Herein we demonstrate the use of LIG, created through a low-cost UV laser, for electrochemical ion selective sensing of plant-available nitrogen (i.e., both ammonium and nitrate ions: NH4+ and NO3-) in soil samples. The laser used to create the LIG was operated at distinct pulse rates (10, 20, 30, 40, and 50 ...


Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John N. Harb, Jonathan C. Claussen, Brian D. Iverson Oct 2018

Electrochemical Glucose Sensors Enhanced By Methyl Viologen And Vertically Aligned Carbon Nanotube Channels, Benjamin J. Brownlee, Meisam Bahari, John N. Harb, Jonathan C. Claussen, Brian D. Iverson

Jonathan C. Claussen

Free-standing, vertically aligned carbon nanotubes (VACNTs) were patterned into 16 µm diameter microchannel arrays for flow-through electrochemical glucose sensing. Non-enzymatic sensing of glucose was achieved by the chemical reaction of glucose with methyl viologen (MV) at an elevated temperature and pH (0.1 M NaOH), followed by the electrochemical reaction of reduced-MV with the VACNT surface. The MV sensor required no functionalization (including no metal) and was able to produce on average 3.4 electrons per glucose molecule. The current density of the MV sensor was linear with both flow rate and glucose concentration. Challenges with interference chemicals were mitigated ...


The Subject Librarian Newsletter, Engineering And Computer Science, Spring 2018, Buenaventura "Ven" Basco Oct 2018

The Subject Librarian Newsletter, Engineering And Computer Science, Spring 2018, Buenaventura "Ven" Basco

Buenaventura "Ven" Basco

No abstract provided.


The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco Oct 2018

The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco

Buenaventura "Ven" Basco

No abstract provided.