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Articles 15151 - 15180 of 21740

Full-Text Articles in Engineering

Electrical Characterization Of The (La,Ca) (Cr,Co)O3 System, S. R. Sehlin, Harlan U. Anderson, Don M. Sparlin Jan 1995

Electrical Characterization Of The (La,Ca) (Cr,Co)O3 System, S. R. Sehlin, Harlan U. Anderson, Don M. Sparlin

Materials Science and Engineering Faculty Research & Creative Works

The results of electrical conductivity and thermopower measurements are presented for selected (La,Ca)(Cr,Co)O3 compositions. The La1 - xCaxCrO3 compounds are typical p-type small polaron conductors. The La1 - xCaxCrO3 compounds are found to be small polaron conductors at room temperature for x ≤ 0.20 with a higher electrical conductivity than the corresponding chromite's. The electrical conductivity at room temperature is lower for Co-rich compositions than for Cr-rich compositions for compositions containing 10 mol% and 20 mol% Ca. This fact is attributed to the trapping of p-type small polarons at energetically lower Cr sites, resulting in a broad room temperature conductivity …

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A Two-Dimensional Image Model Based On Occlusion And Maximum Entropy, John A. Stuller Jan 1995

A Two-Dimensional Image Model Based On Occlusion And Maximum Entropy, John A. Stuller

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Provides New Insights into the Formation of Two-Dimensional Image Autocorrelation Functions. We Model an Image as a Maximum-Entropy Composition of Individual Occluding Object Images that Have Random Positions, Shapes and Intensities. We Derive the Autocorrelation Function of This Image Model, Give an Example, and Comment on the Reasonableness of the Frequently-Made Assumptions of Autocovariance Separability and Isotropy.

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Fuzzy Logic In Restructurable Flight Control Systems, S. N. Balakrishnan, H. S. Ho Jan 1995

Fuzzy Logic In Restructurable Flight Control Systems, S. N. Balakrishnan, H. S. Ho

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In this paper, a fuzzy logic controller (FLC) is proposed for restructurable flight control systems. The role of the FLC is to stabilize the aircraft upon a fault occurrence. The FLC derives pitch/roll/yaw controls from a generic knowledge base characterized by 49 if-then rules. A linearized model representative of a modern jet fighter provides the basis for the numerical simulation. Simulated faults include various degrees of surface loss at the right stabilator, combined with reduced ailerons and rudder control power. The FLC accomplishes the stabilization task under test conditions without any knowledge of the system parameters. The numerical results demonstrate …

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Catalyst Wetting Efficiency In Trickle-Bed Reactors At High Pressure, Muthanna H. Al-Dahhan, Milorad P. Duduković Jan 1995

Catalyst Wetting Efficiency In Trickle-Bed Reactors At High Pressure, Muthanna H. Al-Dahhan, Milorad P. Duduković

Chemical and Biochemical Engineering Faculty Research & Creative Works

Trickle-Bed Reactors Are Widely Used in Industrial High Pressure Operations (Up to 30 MPa). the Knowledge of Catalyst Wetting Efficiency as a Function of Operating Conditions is Needed for Relating Laboratory and Pilot Scale Reactor Data to Large Scale Reactor Operation. the Available Predictions of the Wetting Efficiency Rest on Data Collected at Atmospheric Pressure. in This Study a Phenomenological Analysis Has Been Developed to Relate the Wetting Efficiency with Operating Conditions Such as Reactor Pressure, Gas and Liquid Flow Rate. Experimental Data for the Wetting Efficiency at High Pressure Have Been Obtained Via a Tracer Technique. the Data Support …

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Teaching Statistical Experimental Design Using A Laboratory Experiment, Douglas K. Ludlow, Kirk H. Schulz, John Erjavec Jan 1995

Teaching Statistical Experimental Design Using A Laboratory Experiment, Douglas K. Ludlow, Kirk H. Schulz, John Erjavec

Chemical and Biochemical Engineering Faculty Research & Creative Works

An Experimental Project Introduces the Concepts of Statistical Experimental Design to Undergraduates in a Laboratory Setting. a Safe, Inexpensive and Easily Operable Experiment Uses a Gas Chromatograph to Give Quantitative Results and to Allow Students to Concentrate on Applying Statistical Skills Without Being Impeded by Complex Equipment or Experimental Methods. One of the Unique Aspects of the Experiment is a Trade‐off between the Two Most Significant Variables, Forcing Students to Compromise in the Selection of Optimum Conditions. Such Compromises Are Typical in Many Real‐world Industrial Situations. the Experiment Has Been Used for Several Years in the Undergraduate Chemical Engineering Laboratories …

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Methsnotrophic Biodegradation Of Trichloroethylene In A Hollow Fiber Membrane Bioreactor, Carol E. Aziz, Mark W. Fitch, Larry K. Linquist, Jonathan G. Pressman, George Georgiou, Gerald E. Speitel Jan 1995

Methsnotrophic Biodegradation Of Trichloroethylene In A Hollow Fiber Membrane Bioreactor, Carol E. Aziz, Mark W. Fitch, Larry K. Linquist, Jonathan G. Pressman, George Georgiou, Gerald E. Speitel

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Biodegradation of Trichloroethlyene (TCE) in a Hollow Fiber Membrane Bioreactor Was Investigated using a Mutant of the Methanotrophic Bacteria, Methylosinus Trichosporium 0B3b. Contaminated Water Flowed through the Lumen (I.e., Fiber Interior), and the Bacteria Circulated through the Shell Side of the Membrane Module and an External Growth Reactor. in Mass Transfer Studies with a Radial Cross-Flow Membrane Module, 78.3-99.9% of the TCE Was Removed from the Lumen at Hydraulic Residence Times of 3-15 Min in the Lumen and the Shell. in Biodegradation Experiments, 80-95% of the TCE Was Removed from the Lumen at Hydraulic Residence Times of 5-9 Min in …

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Solubility Of Sodium Chloride In Supercritical Water: A Molecular Dynamics Study, S. T. Cui, J. G. Harris Jan 1995

Solubility Of Sodium Chloride In Supercritical Water: A Molecular Dynamics Study, S. T. Cui, J. G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

We study the solubility of sodium chloride in steam and supercritical water at temperatures from 450 to 550 °C and pressures from 100 to 300 bar as predicted by the simple point charge water model and a simple model of the ions. We calculated the chemical potential of the sodium chloride dimer in supercritical water using a Kirkwood coupling parameter integration in which we computed via molecular simulation the reversable work required to increase the NaCl-water interactions from some reduced value to their full strength. The contribution to the chemical potential of the NaCl particle with reduced interactions we computed …

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Learning To Ignore: Psychophysics And Computational Modeling Of Fast Learning Of Direction In Noisy Motion Stimuli, Lucia M. Vaina, V. Sundareswaran, John G. Harris Jan 1995

Learning To Ignore: Psychophysics And Computational Modeling Of Fast Learning Of Direction In Noisy Motion Stimuli, Lucia M. Vaina, V. Sundareswaran, John G. Harris

Electrical and Computer Engineering Faculty Research & Creative Works

The effects of practice on the discrimination of direction of motion in briefly presented noisy dynamic random dot patterns are investigated in several forced-choice psychophysical tasks. We found that the percentage of correct responses on any specific task increases linearly with repetition of trials within roughly 200 trials from about chance to a performance of 90% or better. The level of performance remained constant or improved over several days, and in most instances, it did not transfer when stimulus parameters changed. We used a modified Radial Basis Function (RBF) representation to model the psychophysical tasks. The performance of the model …

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Performance Of Ai Methods In Detecting Melanoma, Arve Kjoelen, M. J. Thompson, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker Jan 1995

Performance Of Ai Methods In Detecting Melanoma, Arve Kjoelen, M. J. Thompson, Scott E. Umbaugh, Randy Hays Moss, William V. Stoecker

Electrical and Computer Engineering Faculty Research & Creative Works

This research has shown that features extracted from color skin tumor images by computer vision methods can be reliable discriminators of malignant tumors from benign ones. Reliability was demonstrated by the monotonically increasing success ratios with increasing training set size and by the small standard deviations from the mean success rates. An average success rate of 70 percent in diagnosing melanoma was attained for a training set size of 60 percent. The presence or absence of atypical moles in the training and test sets was shown to have a dramatic impact on the effectiveness of the generated classification rules. This …

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Iron Phosphate Glasses As A Potential Nuclear Waste Disposal Medium, Melissa G. Mesko Jan 1995

Iron Phosphate Glasses As A Potential Nuclear Waste Disposal Medium, Melissa G. Mesko

Masters Theses

”Phosphate glasses containing large amounts of Fe2O3 (up to 43wt%) were studied to determine their potential suitability as nuclear waste disposal glasses for high level radioactive wastes containing large concentrations of iron oxide, phosphate, and fluoride compounds. Glass formation and chemical durability was the prime focus of this study, while properties such as density, thermal expansion, dilatometric softening temperature, and devitrification temperature were examined as well. It was found that large amounts of simulated nuclear waste material (up to 44.4wt% Cs2O or 37.5wt% SrO) could be incorporated into the base iron phosphate glass while retaining …

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Effects Of Specimen Size Reduction On The Transition Curve Of The Charpy V-Notch Impact Test, Lonnie Eugene Schubert Jan 1995

Effects Of Specimen Size Reduction On The Transition Curve Of The Charpy V-Notch Impact Test, Lonnie Eugene Schubert

Masters Theses

"This study was undertaken to correlate the impact properties of ASTM standard full size Charpy V-notch impact specimens to the impact properties of subsize specimens. An ASTM A533-B quenched and tempered plate steel was examined. The fine grained martensitic material had a coarse prior austenite grain size, which resulted in a low upper shelf energy for this material. Three sizes of specimens were included. Specimens were irradiated in the TRIGA Reactor Facility operated by the U. S. Geological Survey in Denver, Colorado, to 1 x 1019 n/cm2 (E > 1 MeV) at 150°C (302°F). Unirradiated and irradiated specimens were …

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Eigenproperties Of Nonclassically Damped Dynamic Systems, Daniel Patrick Malone Jan 1995

Eigenproperties Of Nonclassically Damped Dynamic Systems, Daniel Patrick Malone

Masters Theses

"This thesis develops perturbation series solutions for the eigenvalues and eigenvectors of nonclassically damped dynamic systems for the case where the unperturbed system has repeated eigenvalues. The case of repeated eigenvalues is much more complicated than the case of perturbing a system with distinct eigenvalues. Because of this difficulty, only a specific category of dynamic systems with repeated eigenvalues is addressed. Namely, only those systems that when perturbed have series solutions of the form of a power series. This category of systems can be easily identified by an a priori check developed in the application section of this thesis. The …

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On The Use Of Students For Developing Engineering Laboratories, Bopaya Bidanda, Richard E. Billo Jan 1995

On The Use Of Students For Developing Engineering Laboratories, Bopaya Bidanda, Richard E. Billo

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper describes a unique and innovative approach that solved the dual problem of starting up a new engineering instructional laboratory in a timely manner, and for teaching engineering students advanced skills in Automatic Data Collection. Students enrolled in a special pilot course were used to develop and startup an Automatic Data Collection laboratory. These students were assigned individual Automatic Data Collection technologies of interest and given total responsibility for the successful startup of the laboratory. The organization and structure of the course modeled the typical team oriented project development efforts in industry. Feedback from students showed the course to …

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A New Approch To Low Drift Ta₂O₅ By Ph Reactive Sputtering And Sol-Gel Method, Chang-Soo Kim, Dae-Hyuk Kwon, Byung-Woog Cho, Byung-Ki Sohn Jan 1995

A New Approch To Low Drift Ta₂O₅ By Ph Reactive Sputtering And Sol-Gel Method, Chang-Soo Kim, Dae-Hyuk Kwon, Byung-Woog Cho, Byung-Ki Sohn

Electrical and Computer Engineering Faculty Research & Creative Works

No abstract provided.

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A New Ph-Isfet Based Dissolved Oxygen Sensor, Chang-Soo Kim, Dae-Hyuk Kwon, Byung-Ki Sohn Jan 1995

A New Ph-Isfet Based Dissolved Oxygen Sensor, Chang-Soo Kim, Dae-Hyuk Kwon, Byung-Ki Sohn

Electrical and Computer Engineering Faculty Research & Creative Works

"A new dissolved oxygen sensor based on pH-ISFET has been discussed. A platinum working electrode surrounding a pH-sensing gate of the pH-ISFET electrolyzes dissolved oxygen, resulting in a corresponding pH change. The pH-ISFET can determine dissolved oxygen concentration through detecting this pH change."--Summary

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High Temperature Interfacial Phenomena In Processing Cofired Ceramics For Electronic Packaging Of Semiconductor Devices, P. D. Ownby, D. A. Weirauch Jr., J. E. Lazaroff Jan 1995

High Temperature Interfacial Phenomena In Processing Cofired Ceramics For Electronic Packaging Of Semiconductor Devices, P. D. Ownby, D. A. Weirauch Jr., J. E. Lazaroff

Materials Science and Engineering Faculty Research & Creative Works

No abstract provided.

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A Flux-Weakening Strategy For Current-Regulated Surface-Mounted Permanent-Magnet Machine Drives, Keith Corzine, S. D. Sudhoff, H. J. Hegner Jan 1995

A Flux-Weakening Strategy For Current-Regulated Surface-Mounted Permanent-Magnet Machine Drives, Keith Corzine, S. D. Sudhoff, H. J. Hegner

Electrical and Computer Engineering Faculty Research & Creative Works

Permanent-magnet synchronous machines fed from current-regulated converters feature nearly ideal performance at low-to-moderate speeds. However, as rotor speed increases the back emf rises which results in loss of current regulation and decreased torque. In buried-magnet machine drives, flux weakening is often used to extend the speed range. This paper sets forth a flux-weakening control specifically designed for surface-mounted permanent-magnet machines which is simple and does not require knowledge of the machine or system parameters. The proposed method is demonstrated both experimentally and through the use of computer simulation

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An Efficient Multicomputer Algorithm For The Solution Of Chemical Process Flowsheeting Equations, Fikret Ercal, Neil L. Book, S. Pait, J. J. Fielding Jan 1995

An Efficient Multicomputer Algorithm For The Solution Of Chemical Process Flowsheeting Equations, Fikret Ercal, Neil L. Book, S. Pait, J. J. Fielding

Computer Science Faculty Research & Creative Works

This paper presents a parallel solution method of large sparse systems of linear equations arising in the context of a chemical process flowsheeting application on a message passing multicomputer. To maximize the performance, the algorithm uses a novel matrix decomposition and solution method, called parallel two-phased LU decomposition, which schedules the concurrent tasks in a maximally overlapping manner, and at the same time, tries to minimize the interprocessor data dependencies and obtain optimal load balancing. The forward elimination step is performed concurrently with the parallel two-phased LU decomposition step and backward substitution is parallelized in a piecewise manner. Implementation results …

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Analysis Of A Current-Regulated Brushless Dc Drive, Keith Corzine, S. D. Sudhoff, H. J. Hegner Jan 1995

Analysis Of A Current-Regulated Brushless Dc Drive, Keith Corzine, S. D. Sudhoff, H. J. Hegner

Electrical and Computer Engineering Faculty Research & Creative Works

Current-regulated brushless DC machines are used in a wide variety of applications including robotics, actuators, electric vehicles, and ship propulsion systems. When conducting system analysis of this or any other type of drive, average-value reduced-order models are invaluable since they provide a means of rapidly predicting the electromechanical dynamics and are readily linearized for control system synthesis. In this paper, a highly accurate average-value reduced-order model of a hysteresis current-regulated brushless DC drive is set forth. In so doing it is demonstrated that the drive exhibits five distinct operating modes. The physical cause of each of these modes is explained …

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The Multirate Simulation Of Facts Devices In Power System Dynamics, J. G. Chen, Mariesa Crow Jan 1995

The Multirate Simulation Of Facts Devices In Power System Dynamics, J. G. Chen, Mariesa Crow

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, the multirate method is applied to the problem of simulating the dynamics of a power system which contains fast components such as induction machine loads and FACTS devices. Results concerning the numerical stability and accuracy of the multirate method are presented. Implementation concerns are also addressed by studying an example power system which contains a wide range of time response behavior

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System Modeling And Control Of Smart Structures, Frank J. Kern, Leslie Robert Koval, K. Chandrashekhara, Vittal S. Rao Jan 1995

System Modeling And Control Of Smart Structures, Frank J. Kern, Leslie Robert Koval, K. Chandrashekhara, Vittal S. Rao

Electrical and Computer Engineering Faculty Research & Creative Works

This paper presents multidisciplinary research and curriculum efforts at the University of Missouri-Rolla in the smart structures area. The primary objective of our project is to integrate research results with curriculum development for the benefit of students in electrical, and mechanical and aerospace engineering and engineering mechanics. The approach to the accomplishment of curriculum objectives is the development of a two-course sequence in the smart structures area with an integrated laboratory. The research portion of the project addresses structural identification and robust control methods for smart structures. A brief summary of the research results and a description of curriculum development …

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On-Line Cursive Korean Character Recognition By Using Curvature Models, Chang-Soo Kim, Byung Hwan Jun, Moo Young Kim, Woo Seong Kim, Jaihie Kim Jan 1995

On-Line Cursive Korean Character Recognition By Using Curvature Models, Chang-Soo Kim, Byung Hwan Jun, Moo Young Kim, Woo Seong Kim, Jaihie Kim

Electrical and Computer Engineering Faculty Research & Creative Works

A cursive Korean character consists of several Korean alphabets where connection is present within and among the alphabets. Recognition of Korean characters can be carried out by splitting each character into smaller primitives. Small line segments can be used as the primitives. But this approach requires too much processing time, for there can be many candidate references to be matched to one input character and each reference usually consists of too many primitives. In this paper, we propose an approach using structural curvature models to overcome the difficulties of using small line segments. These models are obtained by segmenting the …

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Remote Detection Of Acoustic Boundaries Using Radiation Imaging Operators, Richard E. Dubroff, Md. Ishfaqur Raza, Thomas J. Herrick Jan 1995

Remote Detection Of Acoustic Boundaries Using Radiation Imaging Operators, Richard E. Dubroff, Md. Ishfaqur Raza, Thomas J. Herrick

Electrical and Computer Engineering Faculty Research & Creative Works

In this paper, we present an acoustic imaging operator. This operator is based upon combining the material boundary conditions at an acoustic boundary and the radiation boundary conditions associated with one way wave propagation. Numerical examples, using the second-order imaging operator, are presented in order to demonstrate the applicability of this method to the detection of two-dimensional boundaries.

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The Fast Affine Projection Algorithm, Steven L. Grant, S. Tavathia Jan 1995

The Fast Affine Projection Algorithm, Steven L. Grant, S. Tavathia

Electrical and Computer Engineering Faculty Research & Creative Works

This paper discusses a new adaptive filtering algorithm called fast affine projections (FAP). FAP''s key features include LMS like complexity and memory requirements (low), and RLS like convergence (fast) for the important case where the excitation signal is speech. Another of FAP''s important features is that it causes no delay in the input or output signals. In addition, the algorithm is easily regularized resulting in robust performance even for highly colored excitation signals. The combination of these features make FAP an excellent candidate for the adaptive filter in the acoustic echo cancellation problem. A simple, low complexity numerical stabilization method …

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Anomalous-Diffusion Model Of Ionic Transport In Oxide Glasses, David L. Sidebottom, Peter F. Green, Richard K. Brow Jan 1995

Anomalous-Diffusion Model Of Ionic Transport In Oxide Glasses, David L. Sidebottom, Peter F. Green, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

The power-law frequency dependence of both the conductivity, (), and permittivity, (), of ion-conducting materials suggests that self-similar or scale-invariant behavior influences the transport of ions at high frequencies. Using an anomalous-diffusion model, we derive relevant power-law expressions for () and () and compare these with measurements performed on LiPO3 glass. Superior fits to the measured data are obtained compared to the commonly used Kohlrausch-Williams-Watts (KWW) description of the electrical modulus, most particularly in the notorious high-frequency regime. Evaluation of our results in terms of an anomalous-diffusion model suggests the dominance of interaction-based constraints to diffusion. © 1995 The American …

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Two Contributions To The Ac Conductivity Of Alkali Oxide Glasses, David L. Sidebottom, Peter F. Green, Richard K. Brow Jan 1995

Two Contributions To The Ac Conductivity Of Alkali Oxide Glasses, David L. Sidebottom, Peter F. Green, Richard K. Brow

Materials Science and Engineering Faculty Research & Creative Works

Although the frequency dependent conductivity of ion-containing glasses often displays scale invariant power law dispersion at high temperatures, the exponent increases to unity at lower temperatures. We report measurements of the conductivity of a series of alkali metaphosphate glasses including a mixed alkali composition and demonstrate that this temperature dependence results from the superposition of two power law dispersions originating from separate mechanism, and does not indicate any intrinsic change in scaling of the process which dominates at high temperatures. © 1995 The American Physical Society.

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Maximum-Likelihood Time Delay Estimation: A New Perspective, John A. Stuller, Nancy Hubing Jan 1995

Maximum-Likelihood Time Delay Estimation: A New Perspective, John A. Stuller, Nancy Hubing

Electrical and Computer Engineering Faculty Research & Creative Works

This Paper Introduces a New Realization for Maximum Likelihood Time-Delay Estimation. the New Realization Illuminatesthe Relationships between Maximum Likelihood Time Delay Estimation and Other Methods. We Obtain the Result by Deriving the Likelihood Function using a Fundamental Method that, Surprisingly, Appears to Be New to The field of Array Processing. This Method is a Natural Complement to the Karhunen-Loeve Transform Having Vector Eigenfunctions and Scalar Eigenvalues, and It Generalizes to M Measurements, M 2 2. Moreover, It Can Be Applied to Other Multichannel estimation problems.

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On A Method For Obtaining Approximate Solutions To Sturm-Liouville Problems, Serge Abrate Jan 1995

On A Method For Obtaining Approximate Solutions To Sturm-Liouville Problems, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A method presented recently to find approximate solutions to a Sturm-Liouville problem is shown to be a special case of a classical weighted residual method. The choice of approximation functions and convergence of the method are also examined. © 1995 American Mathematical Society.

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Vibration Of Point-Supported Rectangular Composite Plates, Serge Abrate Jan 1995

Vibration Of Point-Supported Rectangular Composite Plates, Serge Abrate

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A general approach is presented to study the free vibrations of rectangular symmetrically laminated composite plates with point supports by using the Rayleigh-Ritz method and the Lagrange multiplier technique for enforcing the zero displacement constraints at the support locations. Polynomial approximation functions are used, and the constitutive relationships are written in terms of four lamination parameters. With these lamination parameters, the number of design variables is reduced to a minimum, which is useful for design optimization purposes, while all symmetric lay-ups are considered. This paper illustrates how the lamination parameters can be used for optimal design of vibrating plates. Results …

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Thermal Contact Conductance Of Ceramic Substrate Junctions, K. C. Chung, H. K. Benson, John W. Sheffield Jan 1995

Thermal Contact Conductance Of Ceramic Substrate Junctions, K. C. Chung, H. K. Benson, John W. Sheffield

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

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