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Mechanical and Aerospace Engineering Faculty Research & Creative Works

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Articles 991 - 1020 of 1287

Full-Text Articles in Engineering

Laser Welding Control, Y.-S. Huang, Hai-Lung Tsai, P. Turner, P.-C. Wang Jan 2004

Laser Welding Control, Y.-S. Huang, Hai-Lung Tsai, P. Turner, P.-C. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In laser welding of metallic workpieces, the energetic beam is moved over the workpiece surface to form a pool of molten weld metal that quickly solidifies behind the advance of the laser into a weld nugget. The laser beam produces a keyhole of plasma-containing vapor within the molten pool. Weld nugget porosity, due to entrapment of the vapor, is minimized by continually sensing radiation from the molten metal pool to determine pool depth and width and then controlling laser power and speed to continually produce a weld metal pool wide enough for the liquid to fully expel the vapor and …

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Metal Transfer In Arc Welding, Hai-Lung Tsai, P.-C. Wang Jan 2004

Metal Transfer In Arc Welding, Hai-Lung Tsai, P.-C. Wang

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A double pulse welding current method is disclosed for the generation and transfer of droplets of welding metal from an electrode wire to a workpiece in an arc welding process. A suitable background direct current level is specified to deliver a desired number of droplets to the weld site. During each cycle of droplet formation and transfer, a first increased current pulse is applied to the electrode and arc to generate a droplet on the tip of and electrode and then a second further increased current pulse is applied to timely separate the droplet from the electrode for transport in …

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Airframe Noise Modeling Appropriate For Multidisciplinary Design And Optimization, Serhat Hosder, Bernard Grossman, Joseph A. Schetz, William H. Mason Jan 2004

Airframe Noise Modeling Appropriate For Multidisciplinary Design And Optimization, Serhat Hosder, Bernard Grossman, Joseph A. Schetz, William H. Mason

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Trailing Edge Noise Metric has been developed for constructing response surfaces that may be used for optimization problems involving aerodynamic noise from a clean wing. The modeling approach includes a modified version of a theoretical trailing edge noise prediction and utilizes a high fidelity CFD (RANS) code with a two-equation turbulence model to obtain the characteristic velocity and length scales used in the noise model. The noise metric is not the absolute value of the noise intensity, but an accurate relative noise measure as shown in the validation studies. Parametric studies were performed to investigate the effect of the …

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Automatic Feedback Control Of Mechanical Gas Face Seals Via Clearance Control, Sachin S. Yelma, Robert G. Landers, Brad A. Miller Jan 2004

Automatic Feedback Control Of Mechanical Gas Face Seals Via Clearance Control, Sachin S. Yelma, Robert G. Landers, Brad A. Miller

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An approach based on proper orthogonal decomposition and Galerkin projection is presented for developing low-order nonlinear models of the gas film pressure within mechanical gas face seals. A technique is developed for determining an optimal set of global basis functions for the pressure field using data measured experimentally or obtained numerically from simulations of the seal motion. The reduced-order gas film models are shown to be computationally efficient compared to full-order models developed using the conventional semidiscretization methods. An example of a coned mechanical gas face seal in a flexibly mounted stator configuration is presented. Axial and tilt modes of …

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Characterization And Modeling Of Local Electromechanical Response In Stress-Biased Piezoelectric Actuators, N. Navapan-Traiphol, Robert W. Schwartz, Daniel S. Stutts, J. Wood Jan 2004

Characterization And Modeling Of Local Electromechanical Response In Stress-Biased Piezoelectric Actuators, N. Navapan-Traiphol, Robert W. Schwartz, Daniel S. Stutts, J. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Numerous investigators have explored the factors that contribute to the high electromechanical performance of stress-biased actuators with particular attention being given to the importance of the extrinsic (domain wall translation) response mechanism. Based on the variation in lateral stress through the thickness of the piezoelectric layer within these devices, it has been suggested that the piezoelectric coefficient varies as a function of position within the layer, though no direct evidence has been previously presented. In this study, the results of Moire interferometry investigations of local strains within these devices are reviewed. The technique permits effective depth-profiling of local deformations at …

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Development And Implementation Of New Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan Jan 2004

Development And Implementation Of New Nonlinear Control Concepts For A Ua, Vijayakumar Janardhan, Derek Schmitz, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A reconfigurable flight control method is developed to be implemented on an Unmanned Aircraft (UA), a thirty percent scale model of the Cessna 150. This paper presents the details of the UAV platform, system identification, reconfigurable controller design, development, and implementation on the UA to analyze the performance metrics. A Crossbow Inertial Measurement Unit provides the roll, pitch and yaw accelerations and rates along with the roll and pitch. The 100400 mini-air data boom from spaceage control provides the airspeed, altitude, angle of attack and the side slip angles. System identification is accomplished by commanding preprogrammed inputs to the control …

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Development And Analysis Of A Feedback Treatment Strategy For Parturient Paresis Of Cows, Radhakant Padhi, S. N. Balakrishnan Jan 2004

Development And Analysis Of A Feedback Treatment Strategy For Parturient Paresis Of Cows, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An intelligent on-line feedback treatment strategy based on nonlinear optimal control theory is presented for the parturient paresis of cows. A limitation in the development of an existing nonlinear mathematical model for the homogeneous system is addressed and further modified to incorporate a control input. A neural network based optimal feedback controller is synthesized for the treatment of the disease. Detailed studies are used to analyze the effectiveness of a feedback medication strategy and it is compared with the current "impulse" strategy. The results show that while the current practice may fail in some cases, especially if it is carried …

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Solid State Aircraft Concept Overview, M. Shahinpoor, P. Jenkins, C. Smith, Kakkattukuzhy M. Isaac, T. Dalbello, Anthony Colozza Jan 2004

Solid State Aircraft Concept Overview, M. Shahinpoor, P. Jenkins, C. Smith, Kakkattukuzhy M. Isaac, T. Dalbello, Anthony Colozza

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Due to recent advances in polymers, photovoltaics, and batteries a unique type of aircraft may be feasible. This is a "solid-state" aircraft, with no conventional mechanical moving parts. Airfoil, propulsion, energy production, energy storage and control are combined in an integrated structure. The key material of this concept is an ionic polymeric-metal composite (IPMC) that provides source of control and propulsion. This material has the unique capability of deforming in an electric field and returning to its original shape when the field is removed. Combining the IPMC with thin-film batteries and thin-film photovoltaics provides both energy source and storage in …

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A Theoretical And Numerical Study Of Thin Film Delamination Using The Pull-Off Test, Zuo Sun, Kai-Tak Wan, David A. Dillard Jan 2004

A Theoretical And Numerical Study Of Thin Film Delamination Using The Pull-Off Test, Zuo Sun, Kai-Tak Wan, David A. Dillard

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An accurate closed-form analytical solution for the strain energy release rate for a thin rectangular film loaded by a central line force using the pull-off test is derived in the presence of a tensile residual stress. the theoretical constitutive relation and the strain energy release rate agree very well with two-dimensional nonlinear finite element analysis for the entire deformation regime ranging from bending plate to stretching membrane. Fracture modes for this pull-off test are also investigated based upon the finite element analysis, offering additional insights to the interfacial delamination. © 2003 Elsevier Ltd. All rights reserved.

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Stationkeeping Of An L₂ Libration Point Satellite With Θ-D Technique, Ming Xin, S. N. Balakrishnan, Henry J. Pernicka, Michael W. Dancer Jan 2004

Stationkeeping Of An L₂ Libration Point Satellite With Θ-D Technique, Ming Xin, S. N. Balakrishnan, Henry J. Pernicka, Michael W. Dancer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A new method for L2 libration-point orbit stationkeeping is proposed in this paper using continuous thrust. The circular restricted three-body problem with Sun and Earth as the two primaries is considered. The unstable orbit about the L2 libration-point requires stationkeeping maneuvers to maintain the nominal path. In this study, an approach, called the "θ-D technique," based on optimal control theory gives a closed-form suboptimal feedback solution to solve this nonlinear control problem. In this approach the Hamiltonian-Jacobi-Bellman (HJB) equation is solved approximately by adding some perturbations to the cost function. The controller is designed such that the actual …

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Design And Technologies For A Smart Composite Bridge, K. Chandrashekhara, Prakash Kumar, Steve Eugene Watkins, Antonio Nanni Jan 2004

Design And Technologies For A Smart Composite Bridge, K. Chandrashekhara, Prakash Kumar, Steve Eugene Watkins, Antonio Nanni

Mechanical and Aerospace Engineering Faculty Research & Creative Works

An all-composite, smart bridge design for shortspan applications is described. The bridge dimensions are 9.14-m (30-ft.) long and 2.74-m (9-ft.) wide. A modular construction based on assemblies of pultruded fiber-reinforced-polymer (FRP) composite tubes is used to meet American Association of State Highway and Transportation Officials (AASHTO) H20 highway load ratings. The hollow tubes are 76 mm (3 in.) square and are made of carbon/vinyl-ester and glass/vinyl-ester. An extensive experimental study was carried out to obtain and compare properties (stiffness, strength, and failure modes) for a quarter portion of the full-sized bridge. The bridge response was measured for design loading, two-million-cycle …

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Optimal Beaver Population Management Using Reduced Order Distributed Parameter Model And Single Network Adaptive Critics, Radhakant Padhi, S. N. Balakrishnan Jan 2004

Optimal Beaver Population Management Using Reduced Order Distributed Parameter Model And Single Network Adaptive Critics, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using a distributed parameter model for beaver population that accounts for their spatial and temporal behavior, an optimal control for a desired distribution of the animals is presented. Optimal solutions are obtained through a "single network adaptive critic" (SNAC) neural network architecture. The objective of this research is to design an "optimal" beaver harvesting scheme for a region of interest.

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Optimal Control Synthesis Of A Class Of Nonlinear Systems Using Single Network Adaptive Critics, Radhakant Padhi, Nishant Unnikrishnan, S. N. Balakrishnan Jan 2004

Optimal Control Synthesis Of A Class Of Nonlinear Systems Using Single Network Adaptive Critics, Radhakant Padhi, Nishant Unnikrishnan, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Adaptive critic (AC) neural network solutions to optimal control designs using dynamic programming has reduced the need of complex computations and storage requirements that typical dynamic programming requires. In this paper, a "single network adaptive critic" (SNAC) is presented. This approach is applicable to a class of nonlinear systems where the optimal control (stationary) equation is explicitly solvable for control in terms of state and costate variables. The SNAC architecture offers three potential advantages; a simpler architecture, significant savings of computational load and reduction in approximation errors. In order to demonstrate these benefits, a real-life micro-electro-mechanical-system (MEMS) problem has been …

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Analysis Of Jet-Wing Distributed Propulsion From Thick Wing Trailing Edges, Serhat Hosder, Joseph A. Schetz, Vance Dippold Jan 2004

Analysis Of Jet-Wing Distributed Propulsion From Thick Wing Trailing Edges, Serhat Hosder, Joseph A. Schetz, Vance Dippold

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Conventional airliners use two to four engines in a Cayley-type arrangement to provide thrust, and the thrust is concentrated right behind the engine. Distributed propulsion is the idea of redistributing the thrust across most, or all, of the wingspan of an aircraft. This can be accomplished by using several large engines and using a duct to spread out the exhaust flow to form a jet-wing or by using many small engines spaced along the span of the wing. Jet-wing distributed propulsion was originally suggested as a way to improve propulsive efficiency. A previous study at Virginia Tech assessed the potential …

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Enhanced Practical Photosynthetic Co₂ Mitigation, David J. Bayless, Morgan Lefay Vis-Chiasson, Gregory G. Kremer Dec 2003

Enhanced Practical Photosynthetic Co₂ Mitigation, David J. Bayless, Morgan Lefay Vis-Chiasson, Gregory G. Kremer

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This process is unique in photosynthetic carbon sequestration. An on-site biological sequestration system directly decreases the concentration of carbon-containing compounds in the emissions of fossil generation units. In this process, photosynthetic microbes are attached to a growth surface arranged in a containment chamber that is lit by solar photons. A harvesting system ensures maximum organism growth and rate of CO2 uptake. Soluble carbon and nitrogen concentrations delivered to the cyanobacteria are enhanced, further increasing growth rate and carbon utilization.

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Utilization Of A Piezoelectric Polymer To Sense Harmonics Of Electromagnetic Torque, Jason Neely, Steven Pekarek, Daniel S. Stutts, Philip Beccue Sep 2003

Utilization Of A Piezoelectric Polymer To Sense Harmonics Of Electromagnetic Torque, Jason Neely, Steven Pekarek, Daniel S. Stutts, Philip Beccue

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, the use of a piezoelectric polymer material to measure the harmonics of electromagnetic torque produced by a permanent magnet synchronous machine is described. The advantages of the polymer include low cost, durability, and flexibility. In addition, wide-bandwidth sensors are relatively easy to design and couple to drive system hardware for harmonic evaluation or to use in feedback-based control. To illustrate the use of the polymer, the electrical and mechanical properties of three sensors are described. The results of time-domain simulation and hardware experiments are used to validate that the voltage obtained from the sensors is linearly related …

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Thermal Properties Of La₀.₅Sr₀.₅Co₁₋ₓnixo₃-D Ceramics Using Photopyroelectric Technique, M. T. Sebastian, C. Preethy Menon, J. Philip, Robert W. Schwartz Sep 2003

Thermal Properties Of La₀.₅Sr₀.₅Co₁₋ₓnixo₃-D Ceramics Using Photopyroelectric Technique, M. T. Sebastian, C. Preethy Menon, J. Philip, Robert W. Schwartz

Mechanical and Aerospace Engineering Faculty Research & Creative Works

La0.5Sr0.5Co1-xNixO3-delta (0<= x<= 0.6) ceramics were prepared using a conventional solid-state ceramic route. The thermal properties—thermal conductivity and heat capacity—of these ceramics were measured by the photopyroelectric technique. The thermal conductivity was found to increase with increasing Ni content. These materials were also found to exhibit a metallic-type variation of thermal conductivity with temperature, and no metal-insulator (M-I) transition was found to occur in any of the samples prepared by this route. However, a M-I transition was found to occur in La0.5Sr0.5CoO3-delta samples prepared by hot pressing. The difference is attributed to variations in oxygen content in the samples.

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Application Of A Diagnostic Tool In Laser Aided Manufacturing Processes, Sashikanth Prakash, Mallikharjuna Rao Boddu, Frank W. Liou Aug 2003

Application Of A Diagnostic Tool In Laser Aided Manufacturing Processes, Sashikanth Prakash, Mallikharjuna Rao Boddu, Frank W. Liou

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Lasers play a vital role in producing parts with high dimensional accuracy, strength and quality in today's rapid prototyping industry. In the process of Laser Metal Deposition, many problems are encountered where the part quality does not meet the required standards. This could be due to the nonconformity of control parameters or unnecessary interactions between the control factors. This paper discusses the implementation of Dr. Genichi Taguchiï's optimization techniques using Design of Experiments (DOE) where a series of fractional factorial experiments are performed on the laser deposition process. The results from these experiments are evaluated with respect to the rate …

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Modeling For The Control Of The Laser Aided Manufacturing Process (Lamp), Mallikharjuna R. Boddu, Vishnu P. Thayalan, Robert G. Landers Aug 2003

Modeling For The Control Of The Laser Aided Manufacturing Process (Lamp), Mallikharjuna R. Boddu, Vishnu P. Thayalan, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Many state-of-the-art Rapid Prototyping (RP) technologies adopt lasers to fabricate 3-D solid parts by material deposition in layers. The ability of these RP technologies to control the process requires a thorough understanding of the process mechanics. This paper presents the analysis of an analytical, dynamic model explaining the complex phenomenon of Laser Aided Manufacturing Process (LAMP). The equilibrium of the dynamic model is analyzed and dynamic simulations are performed to determine its stability characteristics. This model forms the basis for the real-time control of the LAMP.

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Process Control Of Laser Metal Deposition Manufacturing -- A Simulation Study, Robert G. Landers Aug 2003

Process Control Of Laser Metal Deposition Manufacturing -- A Simulation Study, Robert G. Landers

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The laser metal deposition process is a rapid manufacturing operation capable of producing functional prototypes with complex geometries and thin sections. This process inherently contains significant uncertainties and, therefore, extensive experimentation must be performed to determine suitable process parameters. An alternative is to directly control the process on-line using feedback control methodologies. In this paper, a nonlinear control strategy based on feedback linearization is created to automatically regulate the bead morphology and melt pool temperature. Extensive simulation studies are conducted to validate the control strategy.

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Growth And Optical Properties Of Srbi₂Nb₂O₉ Ferroelectric Thin Films Using Pulsed Laser Deposition, Pingxiong Yang, David L. Carroll, John Ballato, Robert W. Schwartz Jun 2003

Growth And Optical Properties Of Srbi₂Nb₂O₉ Ferroelectric Thin Films Using Pulsed Laser Deposition, Pingxiong Yang, David L. Carroll, John Ballato, Robert W. Schwartz

Mechanical and Aerospace Engineering Faculty Research & Creative Works

High quality SrBi2Nb2O9 ferroelectric thin films were fabricated on platinized silicon using pulsed laser deposition assisted with dc glow discharge plasma. Microstructure and ferroelectric properties of the films were characterized. Optical properties of the thin films were studied by spectroscopic ellipsometry and photoluminescence from the ultraviolet to the infrared region. Optical constants, n~0.56 in the infrared region and n~2.24 in the visible spectral region, were determined through multilayer analyses on their respective pseudodielectric functions. The band-gap energy is estimated to be 3.60 eV. A photoluminescence peak at 0.78 µm, whose intensity decreases with decreasing temperature, was observed when excited with …

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Comparison Of 3-, 5-, And 6-Phase Machines For Automotive Charging Applications, B. Zhang, Hua Bai, Walter Eversman, Ronald J. Krefta, Duane J. Buening, Steven Pekarek, Gregory R. Holbrook Jan 2003

Comparison Of 3-, 5-, And 6-Phase Machines For Automotive Charging Applications, B. Zhang, Hua Bai, Walter Eversman, Ronald J. Krefta, Duane J. Buening, Steven Pekarek, Gregory R. Holbrook

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, the performance of a 5-phase claw-pole machine/converter system is compared with those of 3-phase and 6-phase systems of the same volume. It is shown that the acoustic output of the 5-phase machine compares favorably with that of the 6-phase machine and is much lower than that of the 3-phase machine over a majority of the operating range. In addition, the output current produced by the 5-phase machine Is, in general, 6-8% higher than those of the 3-phase and 6-phase machines. These results suggest that for maximizing power density while minimizing cost and acoustic noise, 5-phase machines provide …

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A Single-Element Tuning Fork Piezoelectric Linear Actuator, J. Satonobu, K. Nakamura, S. Ueha, Daniel S. Stutts, James R. Friend Jan 2003

A Single-Element Tuning Fork Piezoelectric Linear Actuator, J. Satonobu, K. Nakamura, S. Ueha, Daniel S. Stutts, James R. Friend

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper describes the design of a piezoelectric tuning-fork, dual-mode motor. The motor uses a single multilayer piezoelectric element in combination with tuning fork and shearing motion to form an actuator using a single drive signal. Finite-element analysis was used in the design of the motor, and the process is described along with the selection of the device's materials and its performance. Swaging was used to mount the multilayer piezoelectric element within the stator. Prototypes of the 25-mm long bidirectional actuator achieved a maximum linear no-load speed of 16.5 cm/s, a maximum linear force of 1.86 N, and maximum efficiency …

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Approximate Dynamic Programming Based Optimal Neurocontrol Synthesis Of A Chemical Reactor Process Using Proper Orthogonal Decomposition, Radhakant Padhi, S. N. Balakrishnan Jan 2003

Approximate Dynamic Programming Based Optimal Neurocontrol Synthesis Of A Chemical Reactor Process Using Proper Orthogonal Decomposition, Radhakant Padhi, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The concept of approximate dynamic programming and adaptive critic neural network based optimal controller is extended in this study to include systems governed by partial differential equations. An optimal controller is synthesized for a dispersion type tubular chemical reactor, which is governed by two coupled nonlinear partial differential equations. It consists of three steps: First, empirical basis functions are designed using the "Proper Orthogonal Decomposition" technique and a low-order lumped parameter system to represent the infinite-dimensional system is obtained by carrying out a Galerkin projection. Second, approximate dynamic programming technique is applied in a discrete time framework, followed by the …

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A Product Architecture-Based Conceptual Dfa Technique, Robert B. Stone, Daniel A. Mcadams, Varghese J. Kayyalethekkel Jan 2003

A Product Architecture-Based Conceptual Dfa Technique, Robert B. Stone, Daniel A. Mcadams, Varghese J. Kayyalethekkel

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A conceptual design for assembly (DFA) method is introduced in this paper. The method incorporates DFA analysis into the conceptual design phase. Current DFA methods, essentially all of which are post-design DFA analyses, are reviewed with emphasis on the popular Boothroyd and Dewhurst method. The product architecture-based conceptual DFA method developed and presented in this article uses two relatively new concepts: the functional basis and the method of module heuristics. The functional basis is used to derive a functional model of a product in a standard language and the module heuristics are applied to the functional model to identify a …

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Modeling Fracture In Laminated Automotive Glazing Impacted By Spherical Featureless Headform, Lokeswarappa R. Dharani, S. R. Mettu, S. Zhao, S. D. Barbat, L. Chai Jan 2003

Modeling Fracture In Laminated Automotive Glazing Impacted By Spherical Featureless Headform, Lokeswarappa R. Dharani, S. R. Mettu, S. Zhao, S. D. Barbat, L. Chai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Laminated glass consisting of two soda lime glass plies adhered by a polyvinyl butyral interlayer (PVB) is used for automotive glazing. This paper describes the application of a dynamic, nonlinear finite element method to investigate the failure modes of a laminated glass subjected to low-velocity impact with a spherical head form. Crack type, crack location and crack initiation time are evaluated using the maximum principal stress and J-integral criterion. Failure occurred due to flexural stresses and not bearing stresses. the first crack always initiated at the center of the outer impacted ply and PVB interface, and later on the exterior …

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Multidimensional, Time-Accurate Cfd Simulation Of Adsorption/Desorption In A Carbon Canister, Xingyan Bai, Kakkattukuzhy M. Isaac, D. Klein, R. Banerjee, J. Edson, W. Breig, L. Oliver Jan 2003

Multidimensional, Time-Accurate Cfd Simulation Of Adsorption/Desorption In A Carbon Canister, Xingyan Bai, Kakkattukuzhy M. Isaac, D. Klein, R. Banerjee, J. Edson, W. Breig, L. Oliver

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Computational fluid dynamics simulations of fixed-bed adiabatic adsorption/desorption processes are presented in this paper. Linear driving force model is used for heat and mass transfer rates. a two-dimensional cylindrical canister and three-dimensional automotive production canister geometry are used to study the adsorption/desorption processes of carbon dioxide in helium carrier gas on Norit B4 activated carbon. the two-dimensional results compare well with the results of Hwang et al. [1]. Computational results as breakthrough curve, adsorption amount and temperature profiles are provided. Results show that non-adiabatic model should be used to fully utilize the activated carbon bed capacity prior to breakthrough. Copyright …

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Experimental Studies Assessing The Repeatability Of A Functional Modeling Derivation Method, Mark A. Kurfman, Michael E. Stock, Robert B. Stone, Jagan Rajan, Kristin L. Wood Jan 2003

Experimental Studies Assessing The Repeatability Of A Functional Modeling Derivation Method, Mark A. Kurfman, Michael E. Stock, Robert B. Stone, Jagan Rajan, Kristin L. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper presents the results of research attempts to substantiate repeatability and uniqueness claims of a functional model derivation method following a hypothesis generation and testing procedure outlined in design research literature. Three experiments are constructed and carried out with a participant pool that possesses a range of engineering design skill levels. the experiments test the utility of a functional model derivation method to produce repeatable functional models for a given product among different designers. in addition to this, uniqueness of the functional models produced by the participants is examined. Results indicate the method enhances repeatability and leads designers toward …

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Mapping Function To Failure Mode During Component Development, Irem Y. Tumer, Robert B. Stone Jan 2003

Mapping Function To Failure Mode During Component Development, Irem Y. Tumer, Robert B. Stone

Mechanical and Aerospace Engineering Faculty Research & Creative Works

When designing aerospace systems, it is essential to provide crucial failure information for failure prevention. Failure modes and effect types of analyses and prior engineering knowledge and experience are commonly used to determine the potential modes of failures a product might encounter during its lifetime. When new products are being considered and designed, this knowledge and information is expanded upon to help designers extrapolate based on their similarity with existing products and the potential design tradeoffs. in this work, we aim to enhance this process by providing design-aid tools which derive similarities between functionality and failure modes. Specifically, this paper …

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Missile Longitudinal Autopilot Design Using A New Suboptimal Nonlinear Control Method, Ming Xin, S. N. Balakrishnan Jan 2003

Missile Longitudinal Autopilot Design Using A New Suboptimal Nonlinear Control Method, Ming Xin, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A missile longitudinal autopilot is designed using a new nonlinear control synthesis technique called the θ-D approximation. The particular θ-D methodology used is referred to as the θ-D H2 design. The technique can achieve suboptimal closed-form solutions to a class of nonlinear optimal control problems in the sense that it solves the Hamilton-Jacobi-Bellman equation approximately by adding perturbations to the cost function. An interesting feature of this method is that the expansion terms in the expression for suboptimal control are nothing but solutions to the state-dependent Riccati equations associated with this class of problems. The θ-D H2 design has the …

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