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Articles 14821 - 14850 of 21740

Full-Text Articles in Engineering

A Class Of Modified Hopfield Networks For Aircraft Identification And Control, Jie Shen, S. N. Balakrishnan Jan 1996

A Class Of Modified Hopfield Networks For Aircraft Identification And Control, Jie Shen, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents a class of modified Hopfield neural networks and their use in solving aircraft optimal control and identification problems. This class of networks consists of parallel recurrent networks which have variable dimensions that can be changed to fit the problems under consideration. It has a structure to implement an inverse transformation that is essential for embedding optimal control gain sequences. Equilibrium solutions are discussed. Energy minimization of the networks leads to identification of the system parameters. Numerical results are provided to identify the dynamics of an aircraft, and the corresponding optimal control is calculated online. Comparison of the …

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Effect Of Inflow Pressure And Wall Heat Transfer On Shock-Induced Combustion/Detonation, B. S. Green, Harlan F. Nelson Jan 1996

Effect Of Inflow Pressure And Wall Heat Transfer On Shock-Induced Combustion/Detonation, B. S. Green, Harlan F. Nelson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Oblique detonation waves are possible ignition mechanisms for scramjet engines. Results from a numerical study of the effects of changing the inflow pressure on oblique detonation wave structure for supersonic flow of a stoichiometric hydrogen-air mixture over a flat plate followed by a ramp are presented. Viscous effects and finite-rate chemistry are considered. Inflow pressure is varied from 0.1 to 1 atmosphere for Mach 4 inflow over a 30-degree ramp. Also, the effect of wall heat transfer rate is examined by comparing adiabatic wall, and constant temperature wall solutions. A separation bubble forms at the intersection of the flat plate …

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A Finite Element Model Of Thermoacoustic Oscillations In Rayleigh Flow, Carlos A. Gutierrez, Walter Eversman Jan 1996

A Finite Element Model Of Thermoacoustic Oscillations In Rayleigh Flow, Carlos A. Gutierrez, Walter Eversman

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The work reported here describes a portion of the development of a finite element model of thermoacoustic oscillations in ducted flows, including three dimensional geometries and nonuniform mean flows with steady heat addition. The thermoacoustic problem is not modeled by a form of the convected wave equation but instead by the conservation equations in primitive form. In this paper the three-dimensional model is reduced to one dimension, applicable to a uniform geometry, but allowing an axially nonuniform flow with sharp gradients in temperature, density, and Mach number. The steady mean flow is computed as a Rayleigh flow. Calculations are shown …

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Target Profile Estimation Using Haar Functions, William R. Bockman, S. N. Balakrishnan, Christopher D'Souza, James Cloutier Jan 1996

Target Profile Estimation Using Haar Functions, William R. Bockman, S. N. Balakrishnan, Christopher D'Souza, James Cloutier

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approach to estimating the target acceleration in a maneuvering target model using Haar function partial summations to model the target acceleration is developed. A kinematic constraint is applied to the maneuvering target model and the effects of the use of this constraint are reviewed.

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Radiative Heating In Scramjet Combustors, Harlan F. Nelson Jan 1996

Radiative Heating In Scramjet Combustors, Harlan F. Nelson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Currently, there is considerable interest in scramjet engines for hypersonic aircraft and missiles. This paper presents preliminary calculations of the radiative heating of the walls of scramjet combustion chambers. The analysis assumes isothermal, constant property flow fields which are representative of actual combustor flow fields. The fuel is H2 and N2 is taken as inert. Temperature in the combustor is on the order of 2000 to 3000 K and pressure is of the order of 5 atm. The combustion products consist mainly of H2O and OH. These gases are strong radiators in the infrared. Radiation heating can be significant because …

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Global Characteristics And Structure Of Hydrogen-Air Counterflow Diffusion Flames, J. Zhao, Kakkattukuzhy M. Isaac, G. L. Pellett Jan 1996

Global Characteristics And Structure Of Hydrogen-Air Counterflow Diffusion Flames, J. Zhao, Kakkattukuzhy M. Isaac, G. L. Pellett

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A model based on similarity transformation, for the nitrogen-diluted, H2-air opposed-jet laminar counterflow diffusion flame (CFDF), was developed independently of earlier models, and numerically solved to study flame location and flame structure and extinction limits. Numerical stiffness is handled by a special treatment of the species production term. Flame location with respect to the stagnation plane is identified as an important parameter that governs H2-air diffusion flames, and physical explanations are given to show how flame location is affected by fuel dilution, strain rate, and Lewis number. Results show very good agreement with experimental extinction conditions. The effect of thermal …

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Analysis Of A Single-Phase Induction Machine With A Shifted Auxiliary Winding, T. A. Walls, Scott D. Sudhoff Jan 1996

Analysis Of A Single-Phase Induction Machine With A Shifted Auxiliary Winding, T. A. Walls, Scott D. Sudhoff

Electrical and Computer Engineering Faculty Research & Creative Works

This paper extents the method of multiple reference frames to the analysis of asymmetrical induction motors with non-orthogonal stator windings, with particular emphasis on the permanent split capacitor (PSC) machine. The predictions of the method are verified by comparison to both experimental results and to results obtained using a machine variable computer simulation. Once verified, the method is used to derive the transfer function relating rotor speed to load torque disturbance, which is of particular interest when analyzing PSC machines driving compressor loads. It is shown that the transfer function exhibits a distinct resonant point, and that the magnitude of …

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Performance Of Laminated Glass Units Under Simulated Windborne Debris Impacts, Richard A. Behr, Paul A. Kremer Jan 1996

Performance Of Laminated Glass Units Under Simulated Windborne Debris Impacts, Richard A. Behr, Paul A. Kremer

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Severe windstorm events such as Hurricane Andrew in 1992 have underscored the vulnerability of building envelopes to breaching under the combined effects of windborne debris impacts and wind pressures. Damage to building interiors and disruption of building functions are exacerbated greatly when building envelopes are breached. When the inner glass ply in a laminated glass window unit is unbroken, the integrity of that part of the building envelope is preserved - provided that the inner glass ply has sufficient resistance to subsequent positive and negative wind pressures. In an effort to develop glazing systems that are resistant to breaching due …

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Biodegradation Of Nonionic Surfactants And Effects Of Oxidative Pretreatment, Craig D. Adams, S. Spitzer, R. M. Cowan Jan 1996

Biodegradation Of Nonionic Surfactants And Effects Of Oxidative Pretreatment, Craig D. Adams, S. Spitzer, R. M. Cowan

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The aerobic biodegradability of nonionic, ethoxylated surfactants and model compounds, and the effect of advanced oxidation pretreatment on the biodegradability of the biorefractory surfactants were examined. Bioassays conducted using a mixed microbial seed showed that the linear primary alcohol ethoxylates, the fatty acid ethoxylates, and also polyethylene glycol were all degradable. The biomineralization of the linear secondary alcohol ethoxylate, ethylene oxide/propylene oxide block copolymer, and alkylphenol ethoxylate was observed to be inhibited to varying degrees. Additional bioassays were conducted on model compounds to examine the effect of specific structural components on biodegradability. Advanced oxidation pretreatment using hydrogen peroxide in combination …

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Comparison Of Linear And Nonlinear Seismic Drift Histories For Midrise Steel Frames, K. Z. Truman, C. Pantelides, Richard A. Behr, Abdeldjelil Belarbi Jan 1996

Comparison Of Linear And Nonlinear Seismic Drift Histories For Midrise Steel Frames, K. Z. Truman, C. Pantelides, Richard A. Behr, Abdeldjelil Belarbi

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The linear and nonlinear seismic responses for two midrise office buildings of five- and 24-storeys were generated by two independent research groups using three commercial analysis packages, ABAQUS, SAP90 and DRAIN-2DX. The results indicate that a variability of up to 25% occurred between the independent research groups' seismic responses. Originally, these models and analyses were generated for the purpose of aiding in the development of load histories for the seismic testing of architectural glass at the University of Missouri-Rolla. The independent researchers were provided with the same structures, accelerograms and basic modelling assumptions and were directed to perform both linear …

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Development Of A Loading History For Seismic Testing Of Architectural Glass In A Shop-Front Wall System, C. P. Pantelides, K. Z. Truman, Richard A. Behr, Abdeldjelil Belarbi Jan 1996

Development Of A Loading History For Seismic Testing Of Architectural Glass In A Shop-Front Wall System, C. P. Pantelides, K. Z. Truman, Richard A. Behr, Abdeldjelil Belarbi

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Moderate earthquakes can pose significant threats to the serviceability and structural integrity of the architectural glazing systems that are included in most building envelope systems. Building envelope damage can cause considerable economic losses due to operational disruptions for extended periods following an earthquake. Furthermore, glazing system structural failures are potentially hazardous to both building occupants and pedestrians. In this paper a systematic analytical study of the effect of the SOOE component of the 1940 El Centro earthquake on the response of a one-storey glass and aluminum shop-front wall system is presented. The seismic response of a one-storey commercial building comprised …

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A Dual Neural Network Architecture For Linear And Nonlinear Control Of Inverted Pendulum On A Cart, S. N. Balakrishnan, Victor Biega Jan 1996

A Dual Neural Network Architecture For Linear And Nonlinear Control Of Inverted Pendulum On A Cart, S. N. Balakrishnan, Victor Biega

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The use of a self-contained dual neural network architecture for the solution of nonlinear optimal control problems is investigated in this study. The network structure solves the dynamic programming equations in stages and at the convergence, one network provides the optimal control and the second network provides a fault tolerance to the control system. We detail the steps in design and solve a linearized and a nonlinear, unstable, four-dimensional inverted pendulum on a cart problem. Numerical results are presented and compared with linearized optimal control. Unlike the previously published neural network solutions, this methodology does not need any external training, …

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Method And Apparatus For Applying Herbicides, Marian Mazurkiewicz Jan 1996

Method And Apparatus For Applying Herbicides, Marian Mazurkiewicz

Mining Engineering Faculty Research & Creative Works

A method of applying herbicide to plants involves delivering a liquid herbicide solution to the plant foliage in a high pressure jet of sufficient energy to physically disrupt the surface of the foliage. The high pressure jet can be either a coherent jet or it can be a stream of droplets. The coherent stream can have sufficient energy to cut the foliage, creating new surfaces that are more wettable by the herbicide solution, and more susceptible to penetration by the herbicide in the solution. The droplets in the droplet stream can be made to be of sufficient size and energy …

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Effect Of Pt Doping On Nucleation And Crystallization In Li2o · 2sio2 Glass: Experimental Measurements And Computer Modeling, K. Lakshmi Narayan, K. F. Kelton, C. S. Ray Jan 1996

Effect Of Pt Doping On Nucleation And Crystallization In Li2o · 2sio2 Glass: Experimental Measurements And Computer Modeling, K. Lakshmi Narayan, K. F. Kelton, C. S. Ray

Materials Science and Engineering Faculty Research & Creative Works

Heterogeneous nucleation and its effects on the crystallization of lithium disilicate glass containing small amounts of Pt are investigated. Measurements of the nucleation frequencies and induction times with and without Pt are shown to be consistent with predictions based on the classical nucleation theory. A realistic computer model for the transformation is presented. Computed differential thermal analysis data (such as crystallization rates as a function of time and temperature) are shown to be in good agreement with experimental results. This modeling provides a new, more quantitative method for analyzing calorimetric data.

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Liquid Phase Behaviour In Nonstoichiometric Calcium-Doped Lanthanum Chromites, J. D. Carter, M. M. Nasrallah, Harlan U. Anderson Jan 1996

Liquid Phase Behaviour In Nonstoichiometric Calcium-Doped Lanthanum Chromites, J. D. Carter, M. M. Nasrallah, Harlan U. Anderson

Materials Science and Engineering Faculty Research & Creative Works

The sinter ability of (La,Ca)CrO3 is analyzed by comparing the liquid phase behavior in A-site excess and A-site deficient compositions (referring to the ABO3 formula). The analysis shows that a series of A-site excess and deficient compositions form distinct liquid phases belonging to the CaO-Cr2O3 phase system. Although both series experience grain growth and densification due to the presence of a liquid phase, the A-site excess compositions exhibit greater shrinkage and sinter to closed porosity, whereas the A-site deficient compositions remain porous. During the final stages of sintering, surplus liquid from the A-site excess material exudes to the free-surface forming …

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Structure And Phase Transformation Of Lanthanum Chromate, J. D. Carter, Harlan U. Anderson, M. G. Shumsky Jan 1996

Structure And Phase Transformation Of Lanthanum Chromate, J. D. Carter, Harlan U. Anderson, M. G. Shumsky

Materials Science and Engineering Faculty Research & Creative Works

Lanthanum chromate (LaCrO4) was synthesized as a low temperature ( < 700°C) intermediate to perovskite-type, lanthanum chromite (LaCrO3). The lattice parameters, atom positions and bond lengths determined from X-ray powder diffraction show that LaCrO4 forms a monazite-type crystal structure. Lanthanum chromate forms a solid solution with Ca, having a solubility between 10 and 20 at %. Thermal analysis shows that at ambient oxygen pressure, LaCrO4 transforms to LaCrO3 at a temperature near 700°C. It also indicates that (La,Ca)CrO4 initially transforms to LaCrO3 and CaCrO4 with the subsequent formation of a (La,Ca)CrO3 solid solution. Evidence of Ca segregation to the surface of (La,Ca) CrO3 particles is given by Auger electron spectroscopy and scanning electron microscopy. © 1996 Chapman & Hall.

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A Robust Path Tracking Algorithm For Homotopy Continuation, S. H. Choi, D. A. Harney, Neil L. Book Jan 1996

A Robust Path Tracking Algorithm For Homotopy Continuation, S. H. Choi, D. A. Harney, Neil L. Book

Chemical and Biochemical Engineering Faculty Research & Creative Works

Conventional path tracking algorithms used in homotopy continuation systems sometimes miss roots owing to jumping from one segment of the homotopy path to another even if there exists homotopy paths to the roots. A robust path tracking algorithm is proposed which loses significant efficiency only on those portions of the path where segment jumping is likely to occur. The method presented here basically performs the predictor-corrector procedure using the Euler predictor and the Newton corrector. Any available algorithm can be used to control the step size. Robustness is achieved by adding the following rule: control the step size so that …

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Catalyst Bed Dilution For Improving Catalyst Wetting In Laboratory Trickle-Bed Reactors, Muthanna H. Al-Dahhan, Milorad P. Duduković Jan 1996

Catalyst Bed Dilution For Improving Catalyst Wetting In Laboratory Trickle-Bed Reactors, Muthanna H. Al-Dahhan, Milorad P. Duduković

Chemical and Biochemical Engineering Faculty Research & Creative Works

The Catalyst Bed Dilution Technique Has Found Rather Widespread Applications as a Means of Producing Reliable and Reproducible Results for Successful Scale-Up and Scale-Down When Testing Commercially Used Catalyst Particle Sizes and Alternative Feedstocks in Small-Scale Laboratory Trickle-Bed Reactors. in Such Small-Diameter Laboratory Units When the Catalyst Used in Commercial Units is Employed as the Only Packing, Low Liquid Velocities Lead to Incomplete Catalyst Utilization Due to Incomplete External Catalyst Wetting, Liquid Maldistribution, and Wall Effects. Diluting the Bed with Fines is Recommended to Remedy These Shortcomings. the Effect of the Bed Dilution with Fines on Catalyst Wetting Efficiency, Pressure …

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Gas Dynamic Unstart In Superdetonative Ram Accelerators, Kaveh Ghorbanian, James D. Sterling Jan 1996

Gas Dynamic Unstart In Superdetonative Ram Accelerators, Kaveh Ghorbanian, James D. Sterling

Business and Information Technology Faculty Research & Creative Works

In this paper we analyze the reflection of non-reacting shock waves as oblique detonation waves. The 2D, steady, inviscid analysis makes use of detonation polar diagrams to identify incident shock angles that lead to reflected detonations, with and without detonation Mach stem formation. The implications of the results for design and operation of superdetonative ram accelerators are explored. The influence of the projectile forebody geometry, the propellant composition, and the takeover velocity is described. We conclude with a discussion of the significance of these parameters on superdetonative ram accelerator unstart phenomena.

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Enhanced Combustion Pulsejet Engines For Mach 0 To 3 Applications, J. Sterling, K. Ghorbanian, T. Sobota Jan 1996

Enhanced Combustion Pulsejet Engines For Mach 0 To 3 Applications, J. Sterling, K. Ghorbanian, T. Sobota

Business and Information Technology Faculty Research & Creative Works

In this paper, we discuss the cyclic operation of an enhanced combustion pulsejet engine (ECPE) applicable in the Mach number range of 0 to 3. The geometry of this engine naturally provides for integration into a new combined cycle engine with ramjets. As in the operation of conventional pulsejets, an ECPE provides engine aspiration, charge compression, combustion and expansion without the use of turbomachinery. The use of modern electronics, fuel injection, and feedback control offers the potential for performance improvements that could make the ECPE a cost-effective competitor for the turbojet engine. This article describes the operating cycle of a …

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An Experimentally Obtainable Heat Source Due To Absorption Of Ultrasound In Biological Media, James L. Drewniak, F. Dunn Jan 1996

An Experimentally Obtainable Heat Source Due To Absorption Of Ultrasound In Biological Media, James L. Drewniak, F. Dunn

Electrical and Computer Engineering Faculty Research & Creative Works

Deposition of heat as a result of loss in an ultrasonic wave may result in damage to biological tissues. The extensive use of ultrasound for diagnostic purposes during pregnancy necessitates the evaluation of thermal risk to a developing fetus during routine clinical exposures. Because of the small ultrasonic absorption coefficient in soft tissues at low megahertz frequencies, temperature elevations exceeding 1 °C are not expected from clinically employed ultrasound systems, and there is no evidence that such small temperature increases can result in deleterious effects. However, when the propagation path includes bone, which is known to be highly lossy, theoretical …

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Effects Of Accelerated Weathering On Architectural Laminated Glass In A Windstorm Environment, Richard A. Behr, Joseph E. Minor, Paul A. Kremer Jan 1996

Effects Of Accelerated Weathering On Architectural Laminated Glass In A Windstorm Environment, Richard A. Behr, Joseph E. Minor, Paul A. Kremer

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

An experimental study was conducted to assess the serviceability and ultimate limit state behavior of a fully glazed architectural laminated glass system under accelerated weathering conditions. Glazed specimens included heat-strengthened laminated glass with a low-emissivity, metallic solar coating on one glass surface next to the polyvinyl butyral interlayer. The laminated glass units were anchored to the aluminum curtain wall frame with a perimeter anchor bead of medium-modulus structural silicone sealant. Accelerated weathering was performed in a manner similar to the provisions of ASTM E773-88 and E774-92. All specimens (weathered and unweathered) were then subjected to a severe windstorm simulation test, …

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Degradation Of Trichloroethylene By Methanol-Grown Cultures Of Methylosinus Trichosporium Ob3b Pp358, Mark W. Fitch, G. E. Speitel, G. Georgiou Jan 1996

Degradation Of Trichloroethylene By Methanol-Grown Cultures Of Methylosinus Trichosporium Ob3b Pp358, Mark W. Fitch, G. E. Speitel, G. Georgiou

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A Soluble Methane Monooxygenase-Constitutive Mutant Strain of Methylosinus Trichosporium OB3b, Strain PP358, Was Grown with Methanol as the Carbon Source, and the Kinetics of Trichloroethylene (TCE) Degradation Were Determined. PP358 Exhibited High TCE Degradation Rates under Both Oxygen- and Carbon-Limiting Conditions. the Optimal Pseudo First-Order Rate Constant for TCE Was Comparable to the Values Measured for Cells Grown with Methane. We Found that Growth under Oxygen-Limiting Conditions Results in Increased Accumulation of Polyhydroxybutyrate, Which in Turn Correlates with Higher Transformation Capacities for TCE. It Was Also Shown that Methanol Inhibits TCE Degradation Only at High Concentrations. Thus, Methanol-Grown Cultures of …

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Plastic Fiber Rolling For Concrete Reinforcement, Jeffery S. Thomas Jan 1996

Plastic Fiber Rolling For Concrete Reinforcement, Jeffery S. Thomas

Masters Theses

"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 …

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Stock Market Prediction Using Different Neural Network Classification Architectures, Karsten Schierholt, Cihan H. Dagli Jan 1996

Stock Market Prediction Using Different Neural Network Classification Architectures, Karsten Schierholt, Cihan H. Dagli

Engineering Management and Systems Engineering Faculty Research & Creative Works

In recent years, many attempts have been made to predict the behavior of bonds, currencies, stocks, or stock markets. The Standard and Poors 500 Index is modeled using different neural network classification architectures. Most previous experiments used multilayer perceptrons for stock market forecasting. A multilayer perceptron architecture and a probabilistic neural network are used to predict the incline, decline, or steadiness of the index. The results of trading with the advice given by the network is then compared with the maximum possible performance and the performance of the index. Results show that both networks can be trained to perform better …

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Influence Of Formation Processes On Oblique Detonation Wave Stabilization, K. Ghorbanian, J. D. Sterling Jan 1996

Influence Of Formation Processes On Oblique Detonation Wave Stabilization, K. Ghorbanian, J. D. Sterling

Business and Information Technology Faculty Research & Creative Works

In this article we report steady, two-dimensional, inviscid solutions for the near field and far field of a supersonic reactive flow over a variable-double-ramp geometry. The incident shock wave compresses and heats the reactants that will combust after flowing some induction length. Upon reaction, a detonation wave forms and intersects the leading wave at some distance from the ramp surface. In this article, reaction-polar diagrams are developed, and the detonation branch solutions are used to investigate the wave interaction processes that may lead to a steady three-wave structure. By considering this formation process new oblique detonation wave stabilization criteria based …

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Consensus Building Model To Select Casis In Small Communities, Steven W. Mccrary, Colin Othniel Benjamin, Vijay E. Ambavanekar Jan 1996

Consensus Building Model To Select Casis In Small Communities, Steven W. Mccrary, Colin Othniel Benjamin, Vijay E. Ambavanekar

Engineering Management and Systems Engineering Faculty Research & Creative Works

This paper examines: (1) The automated mapping/facilities management and geographic information system (AM/FM/GIS), which are called computer-assisted spatial information systems (CASIS) in this paper, software selection process; (2) develops a knowledge-based, multiattribute, multiobjective, consensus building model (CBM); and (3) establishes the validity for using the exogenously developed CBM for the selection of CASIS software. Model formulation is based on analyzing how well the attributes of the software meet user requirements in four areas: functionality, technical capability, vendor characteristics, and costs. Expert knowledge was gathered from several domain practitioners regarding the ability of GIS software functions to fulfill a user's needs. …

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Optimization For Maximum Performance High-Speed Engines, David W. Riggins Jan 1996

Optimization For Maximum Performance High-Speed Engines, David W. Riggins

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Fuel-air combustion and the generation of irreversibility in high-speed flows are described in terms of the fundamental principles of nonequilibrium, work availability, and entropy increases. Engine thrust is analytically related to the overall engine irreversibility and the degree of combustion: Issues involving mixing enhancement assessment and engine optimization are then formalized and clarified. The concept of thrust-potential, as used in engine design and optimization, is shown to be a consistent application of the principles and findings of this and related investigations. This work was supported through NASA Grant NAG 1-1189. Special thanks are due to Charles McClinton at NASA Langley …

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Hamiltonian Based Adaptive Critics For Missile Guidance, S. N. Balakrishnan, Jie Shen Jan 1996

Hamiltonian Based Adaptive Critics For Missile Guidance, S. N. Balakrishnan, Jie Shen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Hamiltonian based adaptive critic structure is proposed for solving missile guidance problems. This structure consists of a supervisor neural network called 'critic' and a controller network called 'action'. Together they are used to solve model-based guidance problems. The advantage of this approach is that: i) the training data for each network is created by the other network, ii) the converged solutions yield near optimal guidance over the entire span of the training range, and iii) they can be used as feedback controllers though trained off-line. A main contribution is that we establish a direct link between traditional optimal control …

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Non-Axisymmetric Matrix Cracking And Interface Debonding With Friction In Ceramic Composites, F. S. Ji, Lokeswarappa R. Dharani Jan 1996

Non-Axisymmetric Matrix Cracking And Interface Debonding With Friction In Ceramic Composites, F. S. Ji, Lokeswarappa R. Dharani

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An three-dimensional analytical model based on the principle of minimum potential energy is developed and applied to determine the stress state in a discrete fiber/matrix composite cylinder subjected to axial tensile loading in the fiber direction and containing a non-symmetric transverse matrix crack and an interface debond. The friction over the debonded interface is incorporated into the analysis. The strain energy release rates associated with the matrix crack and the interface debonding under the combination of the applied load and the interface frictional force are computed. The strain energy release rate criterion has been employed to evaluate the critical applied …

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