1-20 of 35
Additive manufacturing
Close
Save search
Follow your search
Access your saved searches in your account
Would you like to receive an alert when new items match your search?
Close Modal
Sort by
Proceedings Papers

Physics-Informed Gaussian Process Based Optimal Control of Laser Powder Bed Fusion

Available to Purchase

Yong Ren, Qian Wang
Proc. ASME. DSCC2020, Volume 2: Intelligent Transportation/Vehicles; Manufacturing; Mechatronics; Engine/After-Treatment Systems; Soft Actuators/Manipulators; Modeling/Validation; Motion/Vibration Control Applications; Multi-Agent/Networked Systems; Path Planning/Motion Control; Renewable/Smart Energy Systems; Security/Privacy of Cyber-Physical Systems; Sensors/Actuators; Tracking Control Systems; Unmanned Ground/Aerial Vehicles; Vehicle Dynamics, Estimation, Control; Vibration/Control Systems; Vibrations, V002T24A001, October 5–7, 2020
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2020-3197
https://doi.org/10.1115/DSCC2020-3197
View Paper titled, Physics-Informed Gaussian Process Based Optimal Control of Laser Powder Bed Fusion
Open the PDF for Physics-Informed Gaussian Process Based Optimal Control of Laser Powder Bed Fusion in another window
Topics: Lasers, Optimal control, Physics, Computer software, Modeling, Additive manufacturing, Algorithms, Dynamics (Mechanics), Finite element analysis, Simulation results
Proceedings Papers

A Control-Oriented Dynamical Model of Deposited Droplet Volume in Electrohydrodynamic Jet Printing

Available to Purchase

Isaac A. Spiegel, Tom van de Laar, Tom Oomen, Kira Barton
Proc. ASME. DSCC2020, Volume 2: Intelligent Transportation/Vehicles; Manufacturing; Mechatronics; Engine/After-Treatment Systems; Soft Actuators/Manipulators; Modeling/Validation; Motion/Vibration Control Applications; Multi-Agent/Networked Systems; Path Planning/Motion Control; Renewable/Smart Energy Systems; Security/Privacy of Cyber-Physical Systems; Sensors/Actuators; Tracking Control Systems; Unmanned Ground/Aerial Vehicles; Vehicle Dynamics, Estimation, Control; Vibration/Control Systems; Vibrations, V002T24A003, October 5–7, 2020
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2020-3238
https://doi.org/10.1115/DSCC2020-3238
View Paper titled, A Control-Oriented Dynamical Model of Deposited Droplet Volume in Electrohydrodynamic Jet Printing
Open the PDF for A Control-Oriented Dynamical Model of Deposited Droplet Volume in Electrohydrodynamic Jet Printing in another window
Topics: Drops, Electrohydrodynamics, Printing, Resolution (Optics), Additive manufacturing, Biotechnology, Dynamic systems, Dynamics (Mechanics), Electronics, Manufacturing
Proceedings Papers

A Numerical Investigation of an Eddy Current Sensor for Detecting Small Defects in Metal Additive Manufacturing

Available to Purchase

Zhengya Guo, Kok-Meng Lee, Bingjie Hao, Zhenhua Xiong
Proc. ASME. DSCC2020, Volume 2: Intelligent Transportation/Vehicles; Manufacturing; Mechatronics; Engine/After-Treatment Systems; Soft Actuators/Manipulators; Modeling/Validation; Motion/Vibration Control Applications; Multi-Agent/Networked Systems; Path Planning/Motion Control; Renewable/Smart Energy Systems; Security/Privacy of Cyber-Physical Systems; Sensors/Actuators; Tracking Control Systems; Unmanned Ground/Aerial Vehicles; Vehicle Dynamics, Estimation, Control; Vibration/Control Systems; Vibrations, V002T25A003, October 5–7, 2020
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2020-3220
https://doi.org/10.1115/DSCC2020-3220
View Paper titled, A Numerical Investigation of an Eddy Current Sensor for Detecting Small Defects in Metal Additive Manufacturing
Open the PDF for A Numerical Investigation of an Eddy Current Sensor for Detecting Small Defects in Metal Additive Manufacturing in another window
Topics: Additive manufacturing, Eddies (Fluid dynamics), Eddy currents (Electricity), Metals, Sensors
Proceedings Papers

Design and Analysis of a New Mechanism for a Snake Like Robot

Available to Purchase

Johnathon Garcia, Kooktae Lee
Proc. ASME. DSCC2020, Volume 1: Adaptive/Intelligent Sys. Control; Driver Assistance/Autonomous Tech.; Control Design Methods; Nonlinear Control; Robotics; Assistive/Rehabilitation Devices; Biomedical/Neural Systems; Building Energy Systems; Connected Vehicle Systems; Control/Estimation of Energy Systems; Control Apps.; Smart Buildings/Microgrids; Education; Human-Robot Systems; Soft Mechatronics/Robotic Components/Systems; Energy/Power Systems; Energy Storage; Estimation/Identification; Vehicle Efficiency/Emissions, V001T18A002, October 5–7, 2020
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2020-3204
https://doi.org/10.1115/DSCC2020-3204
View Paper titled, Design and Analysis of a New Mechanism for a Snake Like Robot
Open the PDF for Design and Analysis of a New Mechanism for a Snake Like Robot in another window
Topics: Design, Robots, Silicones, Skin, Additive manufacturing, Friction, Kinematics
Proceedings Papers

Exploring the Usability of Retrofit Hardware to Reduce Compensatory Movements in Game Controller-Mediated Telerehabilitation

Available to Purchase

Roni Barak Ventura, Oded Nov, Maurizio Porfiri
Proc. ASME. DSCC2019, Volume 1: Advanced Driver Assistance and Autonomous Technologies; Advances in Control Design Methods; Advances in Robotics; Automotive Systems; Design, Modeling, Analysis, and Control of Assistive and Rehabilitation Devices; Diagnostics and Detection; Dynamics and Control of Human-Robot Systems; Energy Optimization for Intelligent Vehicle Systems; Estimation and Identification; Manufacturing, V001T05A004, October 8–11, 2019
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2019-9041
https://doi.org/10.1115/DSCC2019-9041
View Paper titled, Exploring the Usability of Retrofit Hardware to Reduce Compensatory Movements in Game Controller-Mediated Telerehabilitation
Open the PDF for Exploring the Usability of Retrofit Hardware to Reduce Compensatory Movements in Game Controller-Mediated Telerehabilitation in another window
Topics: Control equipment, Hardware, Engines, Motors, Patient treatment, Additive manufacturing, Biomedicine, Design, Haptics, Health care
Proceedings Papers

Model Predictive Height Control for Direct Energy Deposition

Available to Purchase

Michelle L. Gegel, Douglas A. Bristow, Robert G. Landers
Proc. ASME. DSCC2019, Volume 1: Advanced Driver Assistance and Autonomous Technologies; Advances in Control Design Methods; Advances in Robotics; Automotive Systems; Design, Modeling, Analysis, and Control of Assistive and Rehabilitation Devices; Diagnostics and Detection; Dynamics and Control of Human-Robot Systems; Energy Optimization for Intelligent Vehicle Systems; Estimation and Identification; Manufacturing, V001T10A006, October 8–11, 2019
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2019-9217
https://doi.org/10.1115/DSCC2019-9217
View Paper titled, Model Predictive Height Control for Direct Energy Deposition
Open the PDF for Model Predictive Height Control for Direct Energy Deposition in another window
Topics: Additive manufacturing, Control equipment, Feedback, Flow (Dynamics), Geometry, Heat conduction, Maintenance, Manufacturing, Metals, Robustness
Proceedings Papers

Educational Force Control Using a Modular 2-DOF Serial Robot Manipulator and Low-Cost 2-DOF Force Sensor

Available to Purchase

Stephen Mascaro
Proc. ASME. DSCC2019, Volume 3, Rapid Fire Interactive Presentations: Advances in Control Systems; Advances in Robotics and Mechatronics; Automotive and Transportation Systems; Motion Planning and Trajectory Tracking; Soft Mechatronic Actuators and Sensors; Unmanned Ground and Aerial Vehicles, V003T17A012, October 8–11, 2019
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2019-9245
https://doi.org/10.1115/DSCC2019-9245
View Paper titled, Educational Force Control Using a Modular 2-DOF Serial Robot Manipulator and Low-Cost 2-DOF Force Sensor
Open the PDF for Educational Force Control Using a Modular 2-DOF Serial Robot Manipulator and Low-Cost 2-DOF Force Sensor in another window
Topics: Force control, Force sensors, Manipulators, Robots, Robotics, Additive manufacturing, Hybrid control, Matlab, Mechanical admittance, Motion control
Proceedings Papers

A New Quasi-Steady In-Ground Effect Model for Rotorcraft Unmanned Aerial Vehicles

Available to Purchase

Xiang He, Kam K. Leang
Proc. ASME. DSCC2019, Volume 3, Rapid Fire Interactive Presentations: Advances in Control Systems; Advances in Robotics and Mechatronics; Automotive and Transportation Systems; Motion Planning and Trajectory Tracking; Soft Mechatronic Actuators and Sensors; Unmanned Ground and Aerial Vehicles, V003T21A003, October 8–11, 2019
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2019-9025
https://doi.org/10.1115/DSCC2019-9025
View Paper titled, A New Quasi-Steady In-Ground Effect Model for Rotorcraft Unmanned Aerial Vehicles
Open the PDF for A New Quasi-Steady In-Ground Effect Model for Rotorcraft Unmanned Aerial Vehicles in another window
Topics: Unmanned aerial vehicles, Rotors, Propellers, Thrust, Additive manufacturing, Blades, Compression, Errors, Outflow
Proceedings Papers

Machine-Learning Based Thermal-Geometric Predictive Modeling of Laser Powder Bed Fusion Additive Manufacturing

Available to Purchase

Yong Ren, Qian Wang, Pan Michaleris
Proc. ASME. DSCC2019, Volume 1: Advanced Driver Assistance and Autonomous Technologies; Advances in Control Design Methods; Advances in Robotics; Automotive Systems; Design, Modeling, Analysis, and Control of Assistive and Rehabilitation Devices; Diagnostics and Detection; Dynamics and Control of Human-Robot Systems; Energy Optimization for Intelligent Vehicle Systems; Estimation and Identification; Manufacturing, V001T10A001, October 8–11, 2019
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2019-8995
https://doi.org/10.1115/DSCC2019-8995
View Paper titled, Machine-Learning Based Thermal-Geometric Predictive Modeling of Laser Powder Bed Fusion Additive Manufacturing
Open the PDF for Machine-Learning Based Thermal-Geometric Predictive Modeling of Laser Powder Bed Fusion Additive Manufacturing in another window
Topics: Additive manufacturing, Lasers, Machine learning, Modeling, Temperature, Simulation, Algorithms, Artificial neural networks, Computation, Physics
Proceedings Papers

A Control-Oriented Model for Melt-Pool Volume in Laser Powder Bed Fusion Additive Manufacturing

Available to Purchase

Qian Wang
Proc. ASME. DSCC2019, Volume 1: Advanced Driver Assistance and Autonomous Technologies; Advances in Control Design Methods; Advances in Robotics; Automotive Systems; Design, Modeling, Analysis, and Control of Assistive and Rehabilitation Devices; Diagnostics and Detection; Dynamics and Control of Human-Robot Systems; Energy Optimization for Intelligent Vehicle Systems; Estimation and Identification; Manufacturing, V001T10A002, October 8–11, 2019
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2019-9111
https://doi.org/10.1115/DSCC2019-9111
View Paper titled, A Control-Oriented Model for Melt-Pool Volume in Laser Powder Bed Fusion Additive Manufacturing
Open the PDF for A Control-Oriented Model for Melt-Pool Volume in Laser Powder Bed Fusion Additive Manufacturing in another window
Topics: Additive manufacturing, Lasers, Finite element analysis, Dynamics (Mechanics), Geometry, Computation, Control equipment, Control modeling, Design, Energy budget (Physics)
Proceedings Papers

Weighted-Least Squares Optimization Method for Control and Shape Design of an Adaptive Blade Twist Distribution to Increase Wind Capture

Available to Purchase

Fuzhao Mou, Hamid Khakpour Nejadkhaki, Aaron Estes, John Hall
Proc. ASME. DSCC2018, Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems, V002T17A005, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-9233
https://doi.org/10.1115/DSCC2018-9233
View Paper titled, Weighted-Least Squares Optimization Method for Control and Shape Design of an Adaptive Blade Twist Distribution to Increase Wind Capture
Open the PDF for Weighted-Least Squares Optimization Method for Control and Shape Design of an Adaptive Blade Twist Distribution to Increase Wind Capture in another window
Topics: Blades, Optimization, Shape design, Wind, Stiffness, Design, Stress, Wind velocity, Additive manufacturing, Engineering design
Proceedings Papers

Improved Cross-Coupled Iterative Learning Control for Contouring NURBS Curves

Available to Purchase

Ashley Armstrong, Amy Wagoner Johnson, Andrew Alleyne
Proc. ASME. DSCC2018, Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems, V002T23A005, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-9145
https://doi.org/10.1115/DSCC2018-9145
View Paper titled, Improved Cross-Coupled Iterative Learning Control for Contouring NURBS Curves
Open the PDF for Improved Cross-Coupled Iterative Learning Control for Contouring NURBS Curves in another window
Topics: Iterative learning control, Errors, Trajectories (Physics), Additive manufacturing, Computer-aided design, Control equipment, Design, Engineering simulation, Manufacturing, Simulation
Proceedings Papers

Wide-Band Loop Shaping for Modulation of Energy Transmission in Nonminimum-Phase Systems

Available to Purchase

Tianyu Jiang, Jiong Tang, Xu Chen
Proc. ASME. DSCC2018, Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems, V002T18A001, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-9089
https://doi.org/10.1115/DSCC2018-9089
View Paper titled, Wide-Band Loop Shaping for Modulation of Energy Transmission in Nonminimum-Phase Systems
Open the PDF for Wide-Band Loop Shaping for Modulation of Energy Transmission in Nonminimum-Phase Systems in another window
Topics: Additive manufacturing, Control systems, Design, Dynamics (Mechanics), Electromagnetic spectrum, Filters, Interpolation, Lasers, Noise (Sound), Shapes
Proceedings Papers

Helicopter Swashplate Design and Analysis Using Semi Compliant Mechanism

Available to Purchase

Ayse Tekes, Adeel Khalid, Niko Giannakakos, Alexander Bryant
Proc. ASME. DSCC2018, Volume 3: Modeling and Validation; Multi-Agent and Networked Systems; Path Planning and Motion Control; Tracking Control Systems; Unmanned Aerial Vehicles (UAVs) and Application; Unmanned Ground and Aerial Vehicles; Vibration in Mechanical Systems; Vibrations and Control of Systems; Vibrations: Modeling, Analysis, and Control, V003T30A002, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-8944
https://doi.org/10.1115/DSCC2018-8944
View Paper titled, Helicopter Swashplate Design and Analysis Using Semi Compliant Mechanism
Open the PDF for Helicopter Swashplate Design and Analysis Using Semi Compliant Mechanism in another window
Topics: Compliant mechanisms, Design, Blades, Additive manufacturing, Ball bearings, Injection molding, Matlab, Plates (structures), Rotors, Servomotors
Proceedings Papers

Build Height Control in Directed Energy Deposition Using a Model-Based Feed-Forward Controller

Available to Purchase

Qian Wang, Jianyi Li, Abdalla R. Nassar, Edward W. Reutzel, Wesley Mitchell
Proc. ASME. DSCC2018, Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems, V002T23A003, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-9058
https://doi.org/10.1115/DSCC2018-9058
View Paper titled, Build Height Control in Directed Energy Deposition Using a Model-Based Feed-Forward Controller
Open the PDF for Build Height Control in Directed Energy Deposition Using a Model-Based Feed-Forward Controller in another window
Topics: Control equipment, Feedforward control, Feedback, Lasers, Geometry, Additive manufacturing, Maintenance, Manufacturing
Proceedings Papers

Multi-Physics Design and Modeling of 3D Printed Hydraulically Amplified Dielectric Elastomer Actuators With Large Actuation Strokes

Available to Purchase

Amir Hosein Zamanian, Daniel Allen Porter, Paul Krueger, Edmond Richer
Proc. ASME. DSCC2018, Volume 1: Advances in Control Design Methods; Advances in Nonlinear Control; Advances in Robotics; Assistive and Rehabilitation Robotics; Automotive Dynamics and Emerging Powertrain Technologies; Automotive Systems; Bio Engineering Applications; Bio-Mechatronics and Physical Human Robot Interaction; Biomedical and Neural Systems; Biomedical and Neural Systems Modeling, Diagnostics, and Healthcare, V001T12A006, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-9227
https://doi.org/10.1115/DSCC2018-9227
View Paper titled, Multi-Physics Design and Modeling of 3D Printed Hydraulically Amplified Dielectric Elastomer Actuators With Large Actuation Strokes
Open the PDF for Multi-Physics Design and Modeling of 3D Printed Hydraulically Amplified Dielectric Elastomer Actuators With Large Actuation Strokes in another window
Topics: Actuators, Additive manufacturing, Design, Elastomers, Modeling, Physics, Electrodes, Dielectric liquids, Finite element analysis, Robots
Proceedings Papers

Development of a 3-DOF Tripedal Stick-Slip Microrobotic Mobile Platform for Unconstrained, Omnidirectional Sample Positioning

Available to Purchase

Iman Adibnazari, William S. Nagel, Kam K. Leang
Proc. ASME. DSCC2018, Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems, V002T24A011, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-9229
https://doi.org/10.1115/DSCC2018-9229
View Paper titled, Development of a 3-DOF Tripedal Stick-Slip Microrobotic Mobile Platform for Unconstrained, Omnidirectional Sample Positioning
Open the PDF for Development of a 3-DOF Tripedal Stick-Slip Microrobotic Mobile Platform for Unconstrained, Omnidirectional Sample Positioning in another window
Topics: Stick-slip, Actuators, Errors, Feedforward control, Additive manufacturing, Bearings, Bending (Stress), Cycles, Dynamics (Mechanics), Engineering prototypes
Proceedings Papers

Dynamics, Vibrations and Control Lab Equipment Design

Available to Purchase

Ayse Tekes, Kevin Van Der Horn, Zach Marr, Chong Tian
Proc. ASME. DSCC2018, Volume 2: Control and Optimization of Connected and Automated Ground Vehicles; Dynamic Systems and Control Education; Dynamics and Control of Renewable Energy Systems; Energy Harvesting; Energy Systems; Estimation and Identification; Intelligent Transportation and Vehicles; Manufacturing; Mechatronics; Modeling and Control of IC Engines and Aftertreatment Systems; Modeling and Control of IC Engines and Powertrain Systems; Modeling and Management of Power Systems, V002T16A001, September 30–October 3, 2018
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2018-8913
https://doi.org/10.1115/DSCC2018-8913
View Paper titled, Dynamics, Vibrations and Control Lab Equipment Design
Open the PDF for Dynamics, Vibrations and Control Lab Equipment Design in another window
Topics: Design, Dynamics (Mechanics), Vibration, Finite element analysis, Stress, Students, Accelerometers, Additive manufacturing, Control theory, Deflection
Proceedings Papers

Easy-to-Use 3D Printer for Fabrication of Biological Scaffolds

Available to Purchase

Ashley Armstrong, Andrew Alleyne, Amy Wagoner Johnson
Proc. ASME. DSCC2017, Volume 2: Mechatronics; Estimation and Identification; Uncertain Systems and Robustness; Path Planning and Motion Control; Tracking Control Systems; Multi-Agent and Networked Systems; Manufacturing; Intelligent Transportation and Vehicles; Sensors and Actuators; Diagnostics and Detection; Unmanned, Ground and Surface Robotics; Motion and Vibration Control Applications, V002T16A002, October 11–13, 2017
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2017-5147
https://doi.org/10.1115/DSCC2017-5147
View Paper titled, Easy-to-Use 3D Printer for Fabrication of Biological Scaffolds
Open the PDF for Easy-to-Use 3D Printer for Fabrication of Biological Scaffolds in another window
Topics: Manufacturing, Bone, Feedforward control, Additive manufacturing, Bioengineering, Control equipment, Design, Dynamic models, Engineering disciplines, Feedback
Proceedings Papers

Topology Optimization of Structural Systems Considering Both Compliance and Input Observability

Available to Purchase

Yi Ren, Houpu Yao, Xinfan Lin
Proc. ASME. DSCC2017, Volume 2: Mechatronics; Estimation and Identification; Uncertain Systems and Robustness; Path Planning and Motion Control; Tracking Control Systems; Multi-Agent and Networked Systems; Manufacturing; Intelligent Transportation and Vehicles; Sensors and Actuators; Diagnostics and Detection; Unmanned, Ground and Surface Robotics; Motion and Vibration Control Applications, V002T04A004, October 11–13, 2017
Publisher: American Society of Mechanical Engineers
Paper No: DSCC2017-5236
https://doi.org/10.1115/DSCC2017-5236
View Paper titled, Topology Optimization of Structural Systems Considering Both Compliance and Input Observability
Open the PDF for Topology Optimization of Structural Systems Considering Both Compliance and Input Observability in another window
Topics: Optimization, Topology, Design, Sensors, Stress, Tradeoffs, Actuators, Additive manufacturing, Errors, Filters