Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Mechanical Engineering (13)
- Aerodynamics and Fluid Mechanics (9)
- Automotive Engineering (5)
- Biomechanics and Biotransport (5)
- Biomedical Engineering and Bioengineering (5)
-
- Electro-Mechanical Systems (5)
- Energy Systems (5)
- Aviation (3)
- Management and Operations (3)
- Propulsion and Power (3)
- Aeronautical Vehicles (2)
- Electrical and Computer Engineering (2)
- Structures and Materials (2)
- Acoustics, Dynamics, and Controls (1)
- Applied Mechanics (1)
- Aviation Safety and Security (1)
- Business (1)
- Computational Engineering (1)
- Controls and Control Theory (1)
- Engineering Mechanics (1)
- Engineering Science and Materials (1)
- Materials Science and Engineering (1)
- Mechanics of Materials (1)
- Medicine and Health Sciences (1)
- Multi-Vehicle Systems and Air Traffic Control (1)
- Physical Sciences and Mathematics (1)
- Power and Energy (1)
- Psychiatry and Psychology (1)
- Keyword
-
- Peer-Reviewed Conference Abstracts (4)
- Communication in Aviaiton (3)
- Conference Proceedings (3)
- Mechanical Engineering (3)
- Airfoil (2)
-
- Aviation (2)
- Aviation Managment (2)
- Communication (2)
- Acoustic (1)
- Aerospace Engineering (1)
- Air Traffic Management (1)
- Airline (1)
- Aluminum ; Damage detection ; Ferroelectric materials ; Inspection ; Manufacturing ; Nondestructive evaluation ; Signal processing ; Structural health monitoring (1)
- Apollo (1)
- Articles (1)
- Aviation Security (1)
- Buildings (1)
- Cabin crew (1)
- Composite Wing (1)
- Compressive strength (1)
- Controller Decision Support Tools (1)
- Crack nucleation (1)
- Cracks (1)
- Crm (1)
- Delamination (1)
- Earthquakes (1)
- Ecological Interface Design (1)
- Elasticity (1)
- Energy harvesting (1)
- Engineering (1)
Articles 1 - 23 of 23
Full-Text Articles in Aerospace Engineering
Muscle Synergies Improve Estimation Of Knee Contact Forces During Walking, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd
Muscle Synergies Improve Estimation Of Knee Contact Forces During Walking, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd
Allison Kinney
This study investigates whether use of subject-specific muscle synergies can improve optimization predictions of muscle excitation patterns and knee contact forces during walking. Muscle synergies describe how a small number of neural commands generated by the nervous system can be linearly combined to produce the broad range of muscle electromyographic (EMG) signals measured experimentally. By quantifying the interdependence of individual EMG signals, muscle synergies provide dimensionality reduction for the neural control redundancy problem. Our hypothesis was that use of subjectspecific muscle synergies to limit muscle excitation patterns would improve prediction of muscle EMG patterns at the hip, knee, and ankle …
Muscle Synergy Constraints Improve Prediction Of Knee Contact Force During Gait, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd
Muscle Synergy Constraints Improve Prediction Of Knee Contact Force During Gait, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd
Allison Kinney
Knowledge of patient-specific muscle and joint contact forces during activities of daily living could improve the treatment of movement-related disorders (e.g., osteoarthritis, stroke, cerebral palsy, Parkinson’s disease). Unfortunately, it is currently impossible to measure these quantities directly under common clinical conditions, and calculation of these quantities using computer models is limited by the redundant nature of human neural control (i.e., more muscles than theoretically necessary to actuate the available degrees of freedom in the skeleton). Walking is a particularly important task to understand, since loss of mobility is associated with increased morbidity and decreased quality of life. Though numerous musculoskeletal …
Evaluation Of Different Optimal Control Problem Formulations For Solving The Muscle Redundancy Problem, Friedl De Groote, Allison Kinney, Anil Rao, Benjamin Fregly
Evaluation Of Different Optimal Control Problem Formulations For Solving The Muscle Redundancy Problem, Friedl De Groote, Allison Kinney, Anil Rao, Benjamin Fregly
Allison Kinney
This study evaluates several possible optimal control problem formulations for solving the muscle redundancy problem with the goal of identifying the most efficient and robust formulation. One novel formulation involves the introduction of additional controls that equal the time derivative of the states, resulting in very simple dynamic equations. The nonlinear equations describing muscle dynamics are then imposed as algebraic constraints in their implicit form, simplifying their evaluation. By comparing different problem formulations for computing muscle controls that can reproduce inverse dynamic joint torques during gait, we demonstrate the efficiency and robustness of the proposed novel formulation.
Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd
Synergies Controls Improve Prediction Of Knee Contact Forces And Muscle Excitations During Gait, Benjamin Fregly, Jonathan Walter, Allison Kinney, Scott Banks, Darryl D'Lima, Thor Besier, David Lloyd
Allison Kinney
This study investigates whether use of muscle excitation controls constructed from subjectspecific muscle synergy information can improve optimization prediction of knee contact forces and muscle excitations during walking. Muscle synergies quantify how a large number of experimental muscle electromyographic (EMG) signals can be reconstructed by linearly mixing a much smaller number of neural commands generated by the nervous system. Our hypothesis was that controlling all muscle excitations with a small set of experimentally calculated neural commands would improve prediction of knee contact forces and leg muscle excitations compared to using independently controlled muscle excitations.
Comparison Of Material Properties And Microstructure Of Specimens Built Using The 3d Systems Vanguard Hs And Vanguard Hiq+Hs Sls Systems, T.J. Silverman, Allison Kinney, W. Yong, J.H. Koo
Comparison Of Material Properties And Microstructure Of Specimens Built Using The 3d Systems Vanguard Hs And Vanguard Hiq+Hs Sls Systems, T.J. Silverman, Allison Kinney, W. Yong, J.H. Koo
Allison Kinney
The HiQ upgrade to the 3D Systems Vanguard selective laser sintering (SLS) machine incorporates a revised thermal calibration system and new control software. The paper compares the tensile modulus, tensile strength, elongation at break, flexural modulus, Izod impact resistance and microstructure of two batteries of standard specimens built from recycled Duraform PA (Nylon 12). The first set is built on a Vanguard HS system and the second on the same system with the HiQ upgrade installed. The upgrade reduces user intervention, decreases total build time and improves surface finish. However, using the default processing parameters, tensile, flexure and impact properties …
Construction Of Naca 66-415 Nlf Composite Wing For Acoustic Turbulence Testing, Scott Sawyer, Sean Stewart
Construction Of Naca 66-415 Nlf Composite Wing For Acoustic Turbulence Testing, Scott Sawyer, Sean Stewart
Dr. Scott Sawyer
A design is developed for a Natural Laminar Flow (NLF) wing, to be used at California Polytechnic State University for acoustic turbulence testing. Composite materials are used to produce high-quality surface finishes necessary for laminar flow. A design for the test apparatus is presented and justified. A manufacturing procedure is proposed for the carbon fiber skin, using Vacuum Resin Infusion (VRI). This procedure is tested on a scaled part with satisfactory results; lessons learned are discovered and integrated into the final manufacturing process. The test section has been fit to the Cal Poly wind tunnel, but full implementation has not …
Optimum Grid By Direct Optimization Methods, Ajay Mahajan, Richard Hindman
Optimum Grid By Direct Optimization Methods, Ajay Mahajan, Richard Hindman
Dr. Ajay Mahajan
A solution-adaptive grid procedure based on optimization is developed and applied to the Linearized Viscous Burger's governing equation. The scheme redistributes the grid points as the solution adapts through each successive iteration step to minimize the truncation error terms in the modified equation and satisfy the governing equation. Fist order Roe scheme is used to discretize the governing equation. If the truncation error terms become negligible and the governing equation is satisfied by the scheme then the numerical solution approaches the exact solution.
Grid And Solution Adaptation Via Direct Optimization Methods, Ajay Mahajan
Grid And Solution Adaptation Via Direct Optimization Methods, Ajay Mahajan
Dr. Ajay Mahajan
At present all numerical schemes based on some form of differencing approach are plagued by some lack of accuracy when compared to the exact solution. This lack of accuracy can be attributed to the presence of truncation error in the numerical method. Traditionally the error can be reduced by increasing the number of mesh points in the discrete domain or by implementing a higher order numerical scheme. In recent times the approach has taken a more intelligent direction where adaptation or distribution of the mesh points is affected in such a way to reduce the error. However, grid adaptation with …
Review Of Seal Designs On The Apollo Spacecraft, Joshua Finkbeiner, Patrick Dunlap, Bruce Steinetz, Christopher Daniels
Review Of Seal Designs On The Apollo Spacecraft, Joshua Finkbeiner, Patrick Dunlap, Bruce Steinetz, Christopher Daniels
Dr. Christopher C Daniels
The Apollo spacecraft required a variety of seal designs to support human spaceflight to the moon and to return the crew safely to Earth. High-temperature seals were required for gaps in the thermal protection system to protect the underlying structures from the high heating environment of super orbital reentry. Reliable pressure seals were also required to prevent the loss of habitable atmosphere during missions to the moon...
Ecological Interface Design: Control Space Robustness In Future Trajectory-Based Air Traffic Control Decision Support, Rolf Klomp, Clark Borst, Max Mulder, Gesa Praetorius
Ecological Interface Design: Control Space Robustness In Future Trajectory-Based Air Traffic Control Decision Support, Rolf Klomp, Clark Borst, Max Mulder, Gesa Praetorius
Gesa Praetorius
The current evolution of the Air Traffic Management system towards trajectory-based operations is foreseen to bring large changes to the work domain of the Air Traffic Controller. Although this new form of Air Traffic Control leans heavily on the introduction of advanced automation, the general consensus is that the human must remain actively involved in the decision-making loop, and retain the ultimate responsibility for the safety of operations. These responsibilities, together with the complexities of the new task, require the development of innovative decision support tools. In previous research, and following the principles of Ecological Interface Design, a constraint-based decision …
Inspection And Evaluation Of Dry Fibers In Thick Composites, Vinay Dayal, Sunil Chakrapani, Daniel Barnard
Inspection And Evaluation Of Dry Fibers In Thick Composites, Vinay Dayal, Sunil Chakrapani, Daniel Barnard
Sunil Kishore Chakrapani
This paper presents the investigation of dry fibers in thick composites. Dry fibers can be defined as lack of epoxy in localized regions. These local regions act as potential defects in thick composites under compressive loads and act as an initiation point for defects such as matrix cracking and delamination. Detection and characterization of dryness in glass/epoxy composites, with thickness greater than one inch, is presented in this paper. One inch samples with dry fibers were fabricated and tested. Detection is carried out with the help of air coupled ultrasonics in both through transmission and singled sided inspection. To characterize …
Crack Nucleation In A Peridynamic Solid, S. Silling, O. Weckner, E. Askari, Florin Bobaru
Crack Nucleation In A Peridynamic Solid, S. Silling, O. Weckner, E. Askari, Florin Bobaru
Florin Bobaru Ph.D.
A condition for the emergence of a discontinuity in an elastic peridynamic body is proposed, resulting in a material stability condition for crack nucleation. The condition is derived by determining whether a small discontinuity in displacement, superposed on a possibly large deformation, grows over time. Stability is shown to be determined by the sign of the eigenvalues of a tensor field that depends only on the linearized material properties. This condition for nucleation of a discontinuity in displacement can be interpreted in terms of the dynamic stability of plane waves with very short wavelength. A numerical example illustrates that cracks …
Aeroelastic Energy Harvesting Using A Nonlinear Electromagnetic Oscillator, Katherine Bender, Ndungu Muturi, Alex Spies, Christopher Lee
Aeroelastic Energy Harvesting Using A Nonlinear Electromagnetic Oscillator, Katherine Bender, Ndungu Muturi, Alex Spies, Christopher Lee
Christopher Lee
Results are presented from the design, fabrication and testing of an electromagnetic-inductor device to convert aeroelastic-induced oscillations of an airfoil into electricity. The energy harvester consists of three magnets configured such that the force-displacement relationship can be described by a fifth-degree polynomial. the integration of the harvester into a two-degree-of-freedom, pitch/plunge airfoil system introduces nonlinear stiffness into the plunge direction. This nonlinearity gives rise to limit cycle oscillations which, in turn, are converted to electric power by the harvester. Experimental measurements from wind tunnel tests are compared to predictions of limit cycle response and resulting power generation using a two-degree-of-freedom …
Stall Flutter Measurements From A Two-Degree-Of-Freedom Airfoil With Nonlinear Stiffness, Ndungu Muturi, Alex Spies, Katherine Bender, Christopher Lee
Stall Flutter Measurements From A Two-Degree-Of-Freedom Airfoil With Nonlinear Stiffness, Ndungu Muturi, Alex Spies, Katherine Bender, Christopher Lee
Christopher Lee
Results are presented from an experimental study of stall flutter oscillations from a two-degree-of-freedom, pitch/plunge airfoil system with nonlinear structural stiffness in the plunge direction. With linear (only) structural stiffness, the airfoil system could exhibit a large-pitch-amplitude limit cycle response which is attributed to stall. With the addition of the nonlinear stiffness, the airfoil system could exhibit two classes of limit cycle response: one with low-pitch-amplitude attributed to the structural nonlinearity and one with high-pitch-amplitude attributed to stall. The amplitudes of the limit cycles for cases in which the structurals and aerodynamic nonlinearities co-exist are modulated and remain steady over …
Tools For Engine Diagnostics Under The Nasa Aviation Safety Program, George Baaklini, Andrew Gyekenyesi, K. Smith, Jerzy Sawicki, L. Brasche
Tools For Engine Diagnostics Under The Nasa Aviation Safety Program, George Baaklini, Andrew Gyekenyesi, K. Smith, Jerzy Sawicki, L. Brasche
Jerzy T. Sawicki
No abstract provided.
Technology Engineering And Management In Aviation Chapter:The Evaluation Of Wireless Communication Devices: To Improve In-Flight Security Onboard Commercial Aircraft., Lori Brown, Liang Dong, Anthony Cerrullo
Technology Engineering And Management In Aviation Chapter:The Evaluation Of Wireless Communication Devices: To Improve In-Flight Security Onboard Commercial Aircraft., Lori Brown, Liang Dong, Anthony Cerrullo
Lori J. Brown
As computer and information systems technology advances, industries such as aviation stand to benefit from the overwhelming new advances in hardware, software, and best practices. Technology Engineering and Management in Aviation: Advancements and Discoveries details the essential new developments in technology and management in the aviation industry. Specific and important advances in navigation, air traffic control, and environmental impact all make their way into this volume, which also focuses on management policies keeping up with new technology. This volume is a vital reference for practitioners, management, students, and all those interested in the field of aviation. This chapter will study …
Stochastic Optimal Control In Nonlinear Systems, Celestin Nkundineza
Stochastic Optimal Control In Nonlinear Systems, Celestin Nkundineza
Celestin Nkundineza
Stochastic control is an important area of research in engineering systems that undergo disturbances. Controlling individual states in such systems is critical. The present investigation is concerned with the application of the stochastic optimal control strategy developed by To (2010) and its implementation as well as providing computed results of linear and nonlinear systems under stationary and nonstationary random excitations. In the strategy the feedback matrix is designed based on the achievement of the objectives for individual states in the system through the application of the Lyapunov equation for the system. Each diagonal element in the gain or associated gain …
Structural Damage Assessment Of Propulsions System Components By Impedance Based Health Monitoring, Richard Martin, Andrew Gyekneyesi, Jerzy Sawicki, George Baaklini
Structural Damage Assessment Of Propulsions System Components By Impedance Based Health Monitoring, Richard Martin, Andrew Gyekneyesi, Jerzy Sawicki, George Baaklini
Jerzy T. Sawicki
No abstract provided.
High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion, Albert Juhasz, Jerzy Sawicki
High Temperature Fusion Reactor Cooling Using Brayton Cycle Based Partial Energy Conversion, Albert Juhasz, Jerzy Sawicki
Jerzy T. Sawicki
For some future space power systems using high temperature nuclear heat sources most of the output energy will be used in other than electrical form, and only a fraction of the total thermal energy generated will need to be converted to electrical work. The paper describes the conceptual design of such a “partial energy conversion” system, consisting of a high temperature fusion reactor operating in series with a high temperature radiator and in parallel with dual closed cycle gas turbine (CCGT) power systems, also referred to as closed Brayton cycle (CBC) systems, which are supplied with a fraction of the …
Experimental Evaluation Of Turbine Blade With Potassium Evaporative Cooling, Jessica Townsend
Experimental Evaluation Of Turbine Blade With Potassium Evaporative Cooling, Jessica Townsend
Jessica Townsend
A new method of turbine blade cooling, the Return Flow Cascade, has been developed in which vaporization of a liquid metal such as potassium is used to maintain the blade surface at a nearly uniform temperature. Turbine blades cooled using this technology have lower blade temperature levels compared to that available with conventional air cooling, potentially resulting in higher firing temperatures or a choice of a wider range of materials for the hot gas path. The detailed operation of the Return Flow Cascade is described including fluid mechanic and heat transfer phenomena that occur at high heat flux and gravitational …
A Perching Landing Gear For A Quadcopter, Elsa Culler, Gray Thomas, Christopher Lee
A Perching Landing Gear For A Quadcopter, Elsa Culler, Gray Thomas, Christopher Lee
Christopher Lee
The design, fabrication, and testing of two prototypes of a landing gear mechanism that would allow a quadcopter to grasp and perch upon a branch-like structure are presented. The prototypes are based upon a snapping-claw mechanism that is triggered on the impact of landing. A complaint claw, fabricated using shape deposition manufacturing techniques, can conform to various shapes and contours of perching structures. Results from flight tests with a commercial off-the-shelf quadcopter and zip line tests are presented which demonstrate the performance of the mechanism.
Flight Attendant/Pilot Communication, In A Post 9/11 Environment: Viewed From Both Sides Of The Fortress Door"., Lori Brown
Lori J. Brown
Reports and a recent global survey (Brown, et al., 2010) reported that out of 271 pilots and flight attendants, 13% indicated a discrete wireless communication device would not enhance safety, 18% indicate a slight effect, 33% indicated a device may somewhat enhance safety, and 21% indicated the device would greatly enhance safety. ...
Protecting Airline Passengers In The Age Of Terrorism Chapter:Preparing For In-Flight Security Threats, Lori Brown
Protecting Airline Passengers In The Age Of Terrorism Chapter:Preparing For In-Flight Security Threats, Lori Brown
Lori J. Brown
When it comes to airline security, there is nothing more important than getting people to their destinations safely. Transportation security is also a key component in the overall mission of protecting the nation against terrorist attacks. But airline security is a tricky goal—how do you achieve acceptable levels of security at a reasonable cost and without unduly inconveniencing passengers or invading their privacy? That's exactly what this book is about. Experts examine the latest thinking and analyze the latest research on air passenger security, discuss current practices, and show how technology can solve myriad problems. The book will, in short, …