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Mechanical and Aerospace Engineering Faculty Research & Creative Works
- Keyword
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- Hopfield Neural Nets (2)
- Neurocontrollers (2)
- Optimal Control (2)
- Recurrent Networks (2)
- Stability (2)
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- 15 MA (1)
- 16 G (1)
- 2.5 Cm/S (1)
- 80 V (1)
- Adaptive Control (1)
- Adaptive Critic Based Neural Networks (1)
- Aerospace Control (1)
- Aerospace Vehicle Control (1)
- Angle of Attack (1)
- Case Studies (1)
- Circuit Stability (1)
- Closed Loop Systems (1)
- Control-Constrained Agile Missile Control (1)
- Design Optimization (1)
- Discrete-Time Pole (1)
- Disposal (1)
- Energy Consumption (1)
- Energy Function (1)
- Environmental Factors (1)
- Environmental Performance Analysis (1)
- Feedback (1)
- Feedback Control (1)
- Flightpath Angle (1)
- Force Control (1)
- Frequency Domain Analysis (1)
Articles 1 - 9 of 9
Full-Text Articles in Engineering
Adaptive Critic Based Neural Networks For Control-Constrained Agile Missile Control, Dongchen Han, S. N. Balakrishnan
Adaptive Critic Based Neural Networks For Control-Constrained Agile Missile Control, Dongchen Han, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We investigate the use of an `adaptive critic' based controller to steer an agile missile with a constraint on the angle of attack from various initial Mach numbers to a given final Mach number in minimum time while completely reversing its flightpath angle. We use neural networks with a two-network structure called `adaptive critic' to carry out the optimization process. This structure obtains an optimal controller through solving Hamiltonian equations. This approach needs no external training; each network along with the optimality equations generates the output for the other network. When the outputs are mutually consistent, the controller output is …
Design, Optimization, And The Prototyping Of A Small Tuning-Fork Ultrasonic Piezoelectric Linear Motor, Daniel S. Stutts, James R. Friend
Design, Optimization, And The Prototyping Of A Small Tuning-Fork Ultrasonic Piezoelectric Linear Motor, Daniel S. Stutts, James R. Friend
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The design, optimization, and properties of a prototype small traveling-wave ultrasonic piezoelectric linear motor design are described. A method for optimizing the geometry of the motor to maximize its mechanical output for a given electrical input is described, as is the inherent properties of the design to maximize the motors durability and utilization of the piezoelectric material. Results from testing the motor demonstrate the design and indicate a maximum speed of 2.5 cm/s with a preload of 16 g due to an applied voltage of 80 V/RMS/ at an applied current of 15 mA.
Environmental Performance Analysis Of Solid Freedom Fabrication Processes, Yanchun Luo, Zhiming Ji, Ming-Chuan Leu, R. J. Caudill
Environmental Performance Analysis Of Solid Freedom Fabrication Processes, Yanchun Luo, Zhiming Ji, Ming-Chuan Leu, R. J. Caudill
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper presents a method for analyzing the environmental performance of solid freeform fabrication (SFF) processes. In this method, each process is divided into life phases. Environmental effects of every process phase are then analyzed and evaluated based on the environmental and resource management data. These effects are combined to obtain the environmental performance of the process. The analysis of the environmental performance of SFF processes considers the characteristics of SFF technology, includes material, energy consumption, processes wastes, and disposal. Case studies for three typical SFF processes: stereolithography (SL); selective laser sintering (SLS); and fused deposition modeling (FDM) are presented …
Frequency Domain Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks, Jie Shen, S. N. Balakrishnan
Frequency Domain Robustness Analysis Of Hopfield And Modified Hopfield Neural Networks, Jie Shen, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A variant of Hopfield neural network, called the modified Hopfield network, is formulated in this study. This class of networks consists of parallel recurrent networks which have variable dimensions that can be changed to fit the problem under consideration. It has a structure to implement an inverse transformation that is essential for embedding optimal control gain sequences. Equilibrium solutions of this network are discussed. The robustness of this network and the classical Hopfield network are carried out in the frequency domain using describing functions
Online Identification And Control Of Aerospace Vehicles Using Recurrent Networks, Zhenning Hu, S. N. Balakrishnan
Online Identification And Control Of Aerospace Vehicles Using Recurrent Networks, Zhenning Hu, S. N. Balakrishnan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Methods for estimating the aerospace system parameters and controlling them through two neural networks are presented in this study. We equate the energy function of Hopfield neural network to integral square of errors in the system dynamics and extract the parameters of a system. Parameter convergence is proved. For control, we equate the equilibrium status of a "modified" Hopfield neural network to the steady state Riccati solution with the system parameters as inputs. Through these two networks, we present the online identification and control of an aircraft using its nonlinear dynamics.
Stability Analysis Of Nonlinear Machining Force Controllers, Robert G. Landers, Yen-Wen Lu
Stability Analysis Of Nonlinear Machining Force Controllers, Robert G. Landers, Yen-Wen Lu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Model parameters vary significantly during a normal operation, thus, adaptive techniques have predominately been used. However, model-based techniques that carefully account for changes in the force process have again been examined due to the reduced complexity afforded by such techniques. In this paper, the effect of model parameter variations on the closed-loop stability for two model-based force controllers is examined. It was found that the stability boundary in the process parameter space can be exactly determined for force control systems designed for static force processes. For force control systems designed for first-order force processes, it was found that the stability …
A New Reflection Free Boundary In Uniform Flow Using Mapped Infinite Wave Envelope Elements, Walter Eversman, Indranil Danda Roy
A New Reflection Free Boundary In Uniform Flow Using Mapped Infinite Wave Envelope Elements, Walter Eversman, Indranil Danda Roy
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Variable order mapped infinite wave envelope elements are developed for finite element modeling of acoustic radiation in a uniformly moving medium. These elements can be used outside of the near field as a non-reflecting boundary condition for computations on an infinite domain in which a radiating body is immersed in a moving medium. Mapped infinite wave envelope elements provide a boundary condition equivalent to stiffness, mass, and damping matrices appended to the inner mesh. A demonstration of the characteristics of the mapped infinite wave envelope elements is given in the context of acoustic radiation from a turbofan inlet for which …
Functional Interdependence And Product Similarity Based On Customer Needs, Daniel A. Mcadams, Robert B. Stone, Kristin L. Wood
Functional Interdependence And Product Similarity Based On Customer Needs, Daniel A. Mcadams, Robert B. Stone, Kristin L. Wood
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In this paper, related product functions are determined for a group of approximately 70 consumer products. Using customer need data, a new matrix approach is introduced to identify these relationships. Techniques are then created for determining product similarity. These techniques are clarified and validated through three case studies, including beverage brewers and material-removal products. The results of these case studies are argued to have significant impact on design-by-analogy procedures, benchmarking methods, mass customization strategies and modular design. The paper concludes with a discussion of applications and related procedures for product development.
Hypersonic Drag And Heat Transfer Reduction Using A Forward Facing Jet, Benjamin Meyer, Harlan F. Nelson, David W. Riggins
Hypersonic Drag And Heat Transfer Reduction Using A Forward Facing Jet, Benjamin Meyer, Harlan F. Nelson, David W. Riggins
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A two-dimensional numerical study of the effects of a forward-facing jet located at the stagnation point of a blunt body on wave drag, heat transfer, and skin friction drag is presented for Mach 6.5 flow at 30 km altitude. The full Navier-Stokes equations are used with variable viscosity and thermal conductivity. It is shown that upstream injection can significantly modify the flow field. If the jet conditions are chosen properly, large reductions in drag and heat transfer can be obtained resulting in possible increases in the volumetric efficiency and static stability of aircraft and reductions in heating protection requirements for …