Dr. Gregory N. Washington Profile

Dr. Gregory N. Washington

President at George Mason Univ

SPIE Involvement:

Author

Publications (47)

Proceedings Article | 15 April 2016 Presentation + Paper

Fabrication of a self-sensing electroactive polymer bimorph actuator based on polyvinylidene fluoride and its electrostrictive terpolymer

Leeya Engel, Kyle Van Volkinburg, Moti Ben-David, Gregory Washington, Slava Krylov, Yosi Shacham-Diamand

Proceedings Volume 9798, 97980M (2016) https://doi.org/10.1117/12.2218383

KEYWORDS: Ferroelectric polymers, Actuators, Electroactive polymers, Polymers, Sensing systems, Microelectromechanical systems, Polymeric sensors, Polymeric actuators, Laser Doppler velocimetry, Gold, Electrodes, Thin films, Composites, Silver

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Proceedings Article | 15 April 2016 Presentation + Paper

Use of the shape memory polymer polystyrene in the creation of thin film stretchable sensors for wearable applications

Kyle Van Volkinburg, Thao Nguyen, Jonathan Pegan, Michelle Khine, Gregory Washington

Proceedings Volume 9799, 97990X (2016) https://doi.org/10.1117/12.2218389

KEYWORDS: Sensors, Thin films, Microchannel plates, Polymer thin films, Resistance, Motion models, Metals, Polymers, Picosecond phenomena, Shape memory polymers

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Proceedings Article | 10 March 2014 Paper

All-printed smart structures: a viable option?

John O'Donnell, Farzad Ahmadkhanlou, Hwan-Sik Yoon, Gregory Washington

Proceedings Volume 9057, 905729 (2014) https://doi.org/10.1117/12.2045284

KEYWORDS: Sensors, Smart structures, Printing, Additive manufacturing, 3D printing, Actuators, Electronics, Manufacturing, Fused deposition modeling, Prototyping

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Proceedings Article | 8 March 2014 Paper

Modeling of a PVDF based gesture controller using energy methods

Kyle Van Volkinburg, Gregory Washington

Proceedings Volume 9056, 90562I (2014) https://doi.org/10.1117/12.2046421

KEYWORDS: Ferroelectric polymers, Electrodes, Device simulation, Sensors, Systems modeling, Prototyping, Lead, Beam shaping, Motion models, Matrices

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Proceedings Article | 10 April 2013 Paper

A magneto-rheological fluid-based torque sensor for smart torque wrench application

Farzad Ahmadkhanlou, Gregory Washington

Proceedings Volume 8688, 868819 (2013) https://doi.org/10.1117/12.2009947

KEYWORDS: Microfluidics, Particles, Magnetism, Sensors, Magnetorheological finishing, Magnetic sensors, Systems modeling, Iron, Control systems

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Proceedings Article | 10 April 2010 Paper

Distributed intelligence using gallium nitride based active devices

Prashanth Ramesh, Sriram Krishnamoorthy, Pil Sung Park, Siddharth Rajan, Gregory Washington

Proceedings Volume 7643, 76431W (2010) https://doi.org/10.1117/12.847919

KEYWORDS: Gallium nitride, Etching, Electrodes, Waveguides, Semiconductors, Ultraviolet radiation, Metals, Semiconducting wafers, Intelligence systems, Optical switching

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Proceedings Article | 29 March 2010 Paper

Design and analysis of supporting structure with smart struts for active vibration isolation

Byeongil Kim, Gregory Washington, Rajendra Singh

Proceedings Volume 7645, 76450R (2010) https://doi.org/10.1117/12.847832

KEYWORDS: Model-based design, Control systems, Detection and tracking algorithms, Digital filtering, Electronic filtering, Nonlinear control, Systems modeling, Actuators, Signal attenuation, Modulation

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Proceedings Article | 29 March 2010 Paper

Smart material database compilation and material selection tool development

Jung-Kyu Park, Gregory Washington

Proceedings Volume 7645, 76450I (2010) https://doi.org/10.1117/12.847790

KEYWORDS: Actuators, Smart materials, Shape memory alloys, Databases, Polymers, Mathematical modeling, Thermoelectric materials, Ferroelectric polymers, Dielectrics, Sensors

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Proceedings Article | 3 April 2009 Paper

Development of model-based multispectral controllers for smart material systems

Byeongil Kim, Gregory Washington

Proceedings Volume 7286, 72860D (2009) https://doi.org/10.1117/12.816404

KEYWORDS: Digital filtering, Model-based design, Control systems, Electronic filtering, Systems modeling, Algorithm development, Nonlinear control, Filtering (signal processing), Error analysis, Smart materials

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Proceedings Article | 1 April 2009 Paper

Analysis and design of ferroelectric-based smart antenna structures

Prashanth Ramesh, Gregory Washington

Proceedings Volume 7291, 729110 (2009) https://doi.org/10.1117/12.816411

KEYWORDS: Antennas, Dielectrics, Microwave radiation, Data modeling, Ferroelectric materials, Systems modeling, Electro optical modeling, Dielectric polarization, Thermodynamics, Thin films

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Ferroelectrics in microwave antenna systems offer benefits of electronic tunability, compact size and light weight, speed of operation, high power-handling, low dc power consumption, and potential for low loss and cost. Ferroelectrics allow for the tuning of microwave devices by virtue of the nonlinear dependence of their dielectric permittivity on an applied electric field. Experiments on the field-polarization dependence of ferroelectric thin films show variation in dielectric permittivity of up to 50%. This is in contrast to the conventional dielectric materials used in electrical devices which have a relatively constant permittivity, indicative of the linear field-polarization curve. Ferroelectrics, with their variable dielectric constant introduce greater flexibility in correction and control of beam shapes and beam direction of antenna structures. The motivation behind this research is applying ferroelectrics to mechanical load bearing antenna structures, but in order to develop such structures, we need to understand not just the field-permittivity dependence, but also the coupled electro-thermo-mechanical behavior of ferroelectrics. In this paper, two models are discussed: a nonlinear phenomenological model relating the applied fields, strains and temperature to the dielectric permittivity based on the Devonshire thermodynamic framework, and a phenomenological model relating applied fields and temperature to the dielectric loss tangent. The models attempt to integrate the observed field-permittivity, strain-permittivity and temperature-permittivity behavior into one single unified model and extend the resulting model to better fit experimental data. Promising matches with experimental data are obtained. These relations, coupled with the expression for operating frequency vs. the permittivity are then used to understand the bias field vs. frequency behavior of the antenna. Finally, the effect of the macroscopic variables on the antenna radiation efficiency is discussed.

Proceedings Article | 1 April 2009 Paper

Predicting magnetorheological fluid flow behavior using a multiscale kinetic theory-based model

Monon Mahboob, Farzad Ahmadkhanlou, Christopher Kagarise, Gregory Washington, Stephen Bechtel, Kurt Koelling

Proceedings Volume 7289, 72891W (2009) https://doi.org/10.1117/12.816133

KEYWORDS: Particles, Magnetism, Microfluidics, Fluid dynamics, 3D modeling, Data modeling, Iron, Motion models, Instrument modeling, Spherical lenses

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Proceedings Article | 1 April 2009 Paper

Thermoelectric power generation for hybrid-electric vehicle auxiliary power

Leon Headings, Gregory Washington, Shawn Midlam-Mohler, Joseph Heremans

Proceedings Volume 7290, 72900E (2009) https://doi.org/10.1117/12.816212

KEYWORDS: Thermoelectric materials, Combustion, Prototyping, Resistance, Thermal effects, Temperature metrology, Energy efficiency, Bismuth, Sensors, Solid state electronics

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Proceedings Article | 3 April 2008 Paper

The development of a five DOF magnetorheological fluid-based telerobotic haptic system

Farzad Ahmadkhanlou, Gregory Washington, Stephen Bechtel

Proceedings Volume 6926, 692604 (2008) https://doi.org/10.1117/12.776591

KEYWORDS: Microfluidics, Particles, Haptic technology, Control systems, Fluid dynamics, Magnetism, Iron, Sensors, Feedback control, Systems modeling

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Proceedings Article | 27 March 2008 Paper

Thermoelectrics as elements of hybrid-electric vehicle thermal energy systems

Leon Headings, Gregory Washington, Christopher Jaworski

Proceedings Volume 6930, 69300C (2008) https://doi.org/10.1117/12.776703

KEYWORDS: Thermoelectric materials, Liquids, Resistance, Combustion, Thermal effects, Bismuth, Gases, Systems modeling, Temperature metrology, Energy efficiency

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Proceedings Article | 11 April 2007 Paper

A magnetorheological fluid-based controllable active knee brace

Farzad Ahmadkhanlou, Jamaal Zite, Gregory Washington

Proceedings Volume 6527, 65270O (2007) https://doi.org/10.1117/12.715902

KEYWORDS: Resistance, Magnetism, Prototyping, Fluid dynamics, Microfluidics, Foam, Injuries, Particles, Carbon, Amplifiers

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Proceedings Article | 6 April 2006 Paper

A homogenized strain model for Ni-Mn-Ga driven with collinear field and stress

LeAnn Faidley, Marcelo Dapino, Gregory Washington

Proceedings Volume 6170, 617019 (2006) https://doi.org/10.1117/12.658706

KEYWORDS: Magnetism, Data modeling, Crystals, Nickel, Manganese, Gallium, Optimization (mathematics), Stochastic processes, Homogenization, Transducers

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Ferromagnetic Shape Memory Alloys (FSMAs) in the nickel manganese gallium system have been shown to exhibit large magnetically induced strains of up to 9.5% due to magnetically driven twin variant reorientation. In order for this strain to be reversible, however, an external restoring stress or magnetic field needs to be applied orthogonal to the field and hence the implementation of Ni-Mn-Ga in applications involves the use of electromagnets, which tend to be heavy, bulky and narrowband. In previous work at The Ohio State University a sample of Ni₅₀Mn_28.7Ga_21.3 has been shown to exhibit reversible compressive strains of -4200 microstrain along its [001] direction when a magnetic field is applied along this same direction and no externally applied restoring force is present. This reversible strain is possible because of an internal stress field associated with pinning sites induced during manufacture of the crystal. This paper analyzes the switching between two variant orientations in the presence of magnetic fields (Zeeman energy) and pinning sites (pinning energy) through the formulation of a Gibbs energy functional for the crystal lattice. Minimization of the Gibbs free energy yields a strain kernel which represents the predicted behavior of an idealized 2-dimensional homogeneous single crystal with a single twin boundary and pinning site. While adequate, the kernel has limitations because it does not account for the following: (a) Ni-Mn-Ga consists of a large number of twin variants and boundaries, (b) the strength of the pinning sites may vary, and (c) the local and applied magnetic field will differ due to neighbor-to-neighbor interactions. These limiting factors are addressed in this paper by considering stochastic homogenization. Stochastic distributions are used on the interaction field and on the pinning site strength, yielding a phenomenological model for the bulk strain behavior of Ni₅₀Mn_28.7Ga_21.3. The model quantifies both the hysteresis and saturation of the strain. Constrained optimization is used to determine the necessary parameters and an error analysis is performed to assess the accuracy of the model for various loading conditions.

Proceedings Article | 30 March 2006 Paper

Magnetorheological fluid based automotive steer-by-wire systems

Farzad Ahmadkhanlou, Gregory Washington, Stephen Bechtel, Yingru Wang

Proceedings Volume 6171, 61710I (2006) https://doi.org/10.1117/12.658688

KEYWORDS: Particles, Control systems, Magnetism, Systems modeling, Microfluidics, Sensors, Iron, Resistance, Amplifiers, Haptic technology

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Proceedings Article | 30 March 2006 Paper

A magnetorheological fluid based orthopedic active knee brace

Jamaal Zite, Farzad Ahmadkhanlou, Vijay Neelakantan, Gregory Washington

Proceedings Volume 6171, 61710H (2006) https://doi.org/10.1117/12.658693

KEYWORDS: Resistance, Magnetism, Microfluidics, Fluid dynamics, Particles, Iron, Silicon, Manufacturing, Bone, Water

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Proceedings Article | 27 March 2006 Paper

Shape and vibration control of active laminated plates for RF and optical applications

Amitesh Punhani, Gregory Washington

Proceedings Volume 6166, 61661B (2006) https://doi.org/10.1117/12.658788

KEYWORDS: Ferroelectric polymers, Actuators, Vibration control, Beam shaping, Electrodes, Sensors, Epoxies, Control systems, Reflectors, Feedback control

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Proceedings Article | 19 May 2005 Paper

Vibration confinement of flexible structures using piezoceramic actuators

Hwan-Sik Yoon, Gregory Washington

Proceedings Volume 5757, (2005) https://doi.org/10.1117/12.600334

KEYWORDS: Actuators, Sensors, Ferroelectric polymers, Ferroelectric materials, Optical simulations, Aluminum, Algorithm development, Signal processing, Control systems, Matrices

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Proceedings Article | 19 May 2005 Paper

Orthotropic deflection model for corner-supported plates with segmented in-plane actuators

Jordan Massad, Gregory Washington, Hartono Sumali

Proceedings Volume 5757, (2005) https://doi.org/10.1117/12.601533

KEYWORDS: Ferroelectric polymers, Actuators, Finite element methods, Epoxies, Metals, Reflectors, Polymers, Algorithm development, Electrodes, Matrices

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Proceedings Article | 19 May 2005 Paper

The development of variably compliant haptic systems using magnetorheological fluids

Farzad Ahmadkhanlou, Gregory Washington, Yingru Wang, Stephen Bechtel

Proceedings Volume 5757, (2005) https://doi.org/10.1117/12.600255

KEYWORDS: Particles, Systems modeling, Magnetism, Microfluidics, Haptic technology, 3D modeling, Control systems, Iron, Computer programming, Resistance

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Proceedings Article | 16 May 2005 Paper

Reversible strain in Ni-Mn-Ga with collinear field and stress

LeAnn Faidley, Marcelo Dapino, Gregory Washington, Thomas Lograsso

Proceedings Volume 5761, (2005) https://doi.org/10.1117/12.600210

KEYWORDS: Magnetism, Nickel, Transducers, Manganese, Gallium, Shape memory alloys, Anisotropy, Data modeling, Motion models, Ferromagnetics

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Proceedings Article | 5 May 2005 Paper

Two-stage actuation system using DC motors and piezoelectric actuators for controllable industrial and automotive brakes and clutches

Vijay Neelakantan, Gregory Washington, Norman Bucknor

Proceedings Volume 5762, (2005) https://doi.org/10.1117/12.600296

KEYWORDS: Actuators, Control systems, Smart materials, Performance modeling, Lead, Control systems design, Data modeling, Systems modeling, Magnetism, Microfluidics

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Proceedings Article | 26 July 2004 Paper

Prediction of hysteretic effects in PZT stack actuators using a hybrid modeling strategy

Jung-Kyu Park, Gregory Washington

Proceedings Volume 5383, (2004) https://doi.org/10.1117/12.540217

KEYWORDS: Data modeling, Actuators, Neural networks, Mathematical modeling, Neurons, Switching, Associative arrays, Ferroelectric materials, Performance modeling, Systems modeling

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Proceedings Article | 21 July 2004 Paper

Dynamic behavior and stiffness tuning in solenoid-based Ni-Mn-Ga transducers

LeAnn Faidley, Marcelo Dapino, Gregory Washington, Thomas Lograsso

Proceedings Volume 5387, (2004) https://doi.org/10.1117/12.540039

KEYWORDS: Magnetism, Transducers, Nickel, Gallium, Manganese, Actuators, Data acquisition, Crystals, Manufacturing, Ferromagnetics

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Proceedings Article | 5 August 2003 Paper

Energy-based efficiency of mechanized solid state actuators

Jinyong Joo, Brian Sanders, Gregory Washington, Jason Adams

Proceedings Volume 5056, (2003) https://doi.org/10.1117/12.483447

KEYWORDS: Actuators, Energy efficiency, Solid state electronics, Mechanical efficiency, Ferroelectric materials, Astatine, Analytical research, Aerodynamics, Solid state physics, Ceramics

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Proceedings Article | 5 August 2003 Paper

A broadband vibration control using passive circuits

Gregory Washington, Matt Detrick, Seung-Keon Kwak

Proceedings Volume 5056, (2003) https://doi.org/10.1117/12.483488

KEYWORDS: Capacitors, Vibration control, Capacitance, Resistance, Microcontrollers, Finite element methods, Resistors, Device simulation, Lawrencium, Digital electronics

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Proceedings Article | 1 August 2003 Paper

Analytical and experimental issues in Ni-Mn-Ga transducers

LeAnn Faidley, Marcelo Dapino, Gregory Washington, Thomas Lograsso, Ralph Smith

Proceedings Volume 5049, (2003) https://doi.org/10.1117/12.484011

KEYWORDS: Magnetism, Transducers, Nickel, Manganese, Gallium, Actuators, Shape memory alloys, Magnetostrictive materials, Amplifiers, Ferromagnetics

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Proceedings Article | 22 July 2003 Paper

Positional impact sensing with spatially shaded polyvinylidene fluoride film

Brian Bray, Gregory Washington

Proceedings Volume 5050, (2003) https://doi.org/10.1117/12.484253

KEYWORDS: Sensors, Electrodes, Ferroelectric polymers, Calibration, Temperature metrology, Copper, Data acquisition, Signal processing, Time metrology, Ranging

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Proceedings Article | 15 July 2002 Paper

Comprehensive piezoceramic actuator review

Chris Taylor, Gregory Washington

Proceedings Volume 4701, (2002) https://doi.org/10.1117/12.474681

KEYWORDS: Actuators, Mechanical efficiency, Capacitance, Semiconducting wafers, Energy efficiency, Ferroelectric materials, Electrodes, Sensors, Manufacturing, Adhesives

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Proceedings Article | 11 July 2002 Paper

Simulation and optimization of a smart reconfigurable aperture antenna

Gregory Washington, Hwan-Sik Yoon, Wilhelmus Theunissen

Proceedings Volume 4700, (2002) https://doi.org/10.1117/12.475034

KEYWORDS: Actuators, Antennas, Reflectors, Algorithms, Finite element methods, Beam shaping, Optimization (mathematics), Diffraction, Satellites, Ferroelectric materials

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Proceedings Article | 9 July 2002 Paper

Force feedback system using magneto-rheological fluids for telerobotic surgery

Vijay Neelakantan, Gregory Washington, Randall Wolf

Proceedings Volume 4698, (2002) https://doi.org/10.1117/12.475097

KEYWORDS: Actuators, Control systems, Magnetism, Surgery, Sensors, Foam, Visualization, Motion controllers, Human-machine interfaces, Feedback control

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Proceedings Article | 21 August 2001 Paper

Broadband vibration control using passive circuits in the matrix-second order framework

Seung-Keon Kwak, Gregory Washington

Proceedings Volume 4326, (2001) https://doi.org/10.1117/12.436471

KEYWORDS: Control systems, Vibration control, Capacitors, Capacitance, Finite element methods, Ferroelectric materials, Integrated circuit design, Integrated circuits, Inductance, Matrices

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Proceedings Article | 21 August 2001 Paper

Spatial aperture shading applied to distributed systems for uniform damping control

Bruce Isler, Gregory Washington

Proceedings Volume 4326, (2001) https://doi.org/10.1117/12.436508

KEYWORDS: Actuators, Ferroelectric polymers, Control systems, Sensors, Electrodes, Vibration control, Distributed computing, Beam shaping, Active vibration control, Intelligence systems

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Proceedings Article | 16 August 2001 Paper

Shape control of distributed parameter reflectors using sliding mode control

Fukashi Andoh, Gregory Washington, Vadim Utkin

Proceedings Volume 4334, (2001) https://doi.org/10.1117/12.436596

KEYWORDS: Reflectors, Actuators, Control systems, Switching, Finite element methods, Matrices, Sensors, Information operations, Thermal effects, Logic

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Proceedings Article | 16 August 2001 Paper

Point-actuated aperture antenna development

Marc Angelino, Gregory Washington

Proceedings Volume 4334, (2001) https://doi.org/10.1117/12.436594

KEYWORDS: Actuators, Reflectors, Antennas, Ferroelectric materials, Ferroelectric polymers, Analog electronics, Electromagnetism, Satellites, Motion models, Photonic integrated circuits

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Proceedings Article | 22 June 2000 Paper

Plate vibration modes identification by using piezoelectric sensors

Jun Song, Gregory Washington

Proceedings Volume 3985, (2000) https://doi.org/10.1117/12.388813

KEYWORDS: Sensors, Vibration control, Numerical simulations, Francium, Protactinium, Bessel functions, Ferroelectric materials, Intelligence systems, Intelligent sensors, Intelligent sensor systems

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Proceedings Article | 21 June 2000 Paper

Reconfigurable contour beam generation using a smart subreflector antenna system

Hwan-Sik Yoon, Gregory Washington, Wilhelmus Theunissen

Proceedings Volume 3990, (2000) https://doi.org/10.1117/12.388890

KEYWORDS: Reflectors, Antennas, Actuators, Diffraction, Finite element methods, Reflector design, Beam shaping, Satellites, Human-machine interfaces, Computer programming

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Proceedings Article | 19 June 2000 Paper

Full-state derivative feedback control based on the reciprocal state space framework using smart materials

Seung-Keon Kwak, Gregory Washington, Rama Yedavalli

Proceedings Volume 3984, (2000) https://doi.org/10.1117/12.388797

KEYWORDS: Feedback control, Finite element methods, Smart materials, Systems modeling, Actuators, Computer simulations, Control systems, Ferroelectric materials, Device simulation, Smart structures

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Proceedings Article | 20 July 1999 Paper

Testing and development of doubly curved piezoceramic aperture antennas

Hwan-Sik Yoon, Gregory Washington

Proceedings Volume 3673, (1999) https://doi.org/10.1117/12.354263

KEYWORDS: Antennas, Actuators, Reflectors, Spherical lenses, Ferroelectric materials, Beam shaping, Beam steering, Computer simulations, Intelligence systems, Optical simulations

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Proceedings Article | 9 June 1999 Paper

Thunder actuator modeling and control with classical and fuzzy control algorithm

Jun Song, Gregory Washington

Proceedings Volume 3668, (1999) https://doi.org/10.1117/12.350763

KEYWORDS: Actuators, Fuzzy logic, Composites, Control systems, Aluminum, Ferroelectric materials, Photography, Systems modeling, Spherical lenses, Intelligence systems

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Proceedings Article | 24 July 1998 Paper

Robust intelligent control of structures using piezoceramic materials

Peter Mayhan, Gregory Washington

Proceedings Volume 3323, (1998) https://doi.org/10.1117/12.316314

KEYWORDS: Fuzzy logic, Actuators, Systems modeling, Sensors, Control systems, Process control, Algorithm development, Ferroelectric materials, Intelligence systems, Smart materials

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Proceedings Article | 20 July 1998 Paper

Piezoceramic actuated aperture antennas

Hwan-Sik Yoon, Gregory Washington

Proceedings Volume 3328, (1998) https://doi.org/10.1117/12.320165

KEYWORDS: Antennas, Reflectors, Actuators, Ferroelectric materials, Composites, Computer simulations, Beam shaping, Mathematical modeling, Ferroelectric polymers, Magnetism

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Proceedings Article | 20 July 1998 Paper

Design actuation and control of active patch antennas

Edward Kiely, Gregory Washington, Jennifer Bernhard

Proceedings Volume 3328, (1998) https://doi.org/10.1117/12.320164

KEYWORDS: Antennas, Actuators, Analog electronics, Control systems, Device simulation, Systems modeling, Intelligence systems, Dielectrics, Metals, Skin

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Proceedings Article | 19 June 1997 Paper

Design and testing of an active polyvinylidene fluoride aperture antenna

Gregory Washington

Proceedings Volume 3046, (1997) https://doi.org/10.1117/12.276597

KEYWORDS: Antennas, Ferroelectric polymers, Reflectors, Actuators, Beam shaping, Beam steering, Electrodes, Mechanical engineering, Electromagnetism, Active optics

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