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Articles 751 - 780 of 809
Full-Text Articles in Aerospace Engineering
The Force On A Lattice Defect In An Elastic Body, R. C. Batra
The Force On A Lattice Defect In An Elastic Body, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
It is shown that the force on a lattice defect in an elastic body is, like the force on a disclination in a nematic liquid crystal, a real force which, for equilibrium, must be balanced by an external force applied to the closed surface enclosing the defect. © 1987 Martinus Nijhoff Publishers.
Closed-Loop Dynamic Response Of A Static Scherbius Drive., Aaron J. Miles, B. Lequesne
Closed-Loop Dynamic Response Of A Static Scherbius Drive., Aaron J. Miles, B. Lequesne
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Generalized root-loci techniques, for squirrel-cage motors have been extended to wound-rotor, slip-energy-recovery systems (static Scherbius drive). The influence of a feedback control loop on these root loci is considered. General conclusions on Scherbius drive dynamics, as well as supporting experimental results, are presented.
Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig
Elasto-Composition Waves In Inhomogeneous Solids, R. C. Batra, Manfred Wuttig
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Generalized Root-Loci Theory For The Static Scherbius Drive, B. Lequesne, Aaron J. Miles
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Generalized root-loci techniques, developed in the mid 70's for squirrel cage motors, have been extended in the static Scherbius configuration to wound rotor, slip energy, recovery systems. This arrangement is now applied to large power drives in the 0.5 to 50 MW range. In this paper, general results applicable to all machines are presented for the open-loop control scheme, but only the sub synchronous mode of operation in which a voltage source type inverter is used is addressed. Copyright © 1984 by The Institute of Electrical and Electronics Engineers, Inc.
Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra
Saint-Venant's Principle In Linear Elasticity With Microstructure, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Toupin's version of the Saint-Venant principle in linear elasticity is generalized to the case of linear elasticity with microstructure. That is, it is shown that, for a straight prismatic bar made of an isotropic linear elastic material with microstructure and loaded by a self-equilibrated force system at one end only, the strain energy stored in the portion of the bar which is beyond a distance s from the loaded end decreases exponentially with the distance s. © 1983 Martinus Nijhoff Publishers.
Linear Inversion Method To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Donald E. Hagen, Darryl J. Alofs
Linear Inversion Method To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Donald E. Hagen, Darryl J. Alofs
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Use of a Differential Mobility Analyzer to Perform Aerosol Size Spectrum Measurements Requires an Inversion Method to Go from the Measured Sensor Responses to the Desired Size Spectrum Information. Here We Present a Linear Inversion Method that Can Be Run on a Microcomputer or a Small Minicomputer. It Does Not Use Some of the Approximations Made in the Techniques Currently Available and Hence Gives Better Inversion Accuracy. the Method Shows Good Immunity to Both Random and Systematic Experimental Error. It is Applied to Numerous Test Case Aerosols. © 1983 Elsevier Science Publishing Co., Inc.
A Potential Problem With The Tsi Electrostatic Aerosol Classifier, Darryl J. Alofs, Max B. Trueblood
A Potential Problem With The Tsi Electrostatic Aerosol Classifier, Darryl J. Alofs, Max B. Trueblood
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar
Inversion To Obtain Aerosol Size Distributions From Measurements With A Differential Mobility Analyzer, Darryl J. Alofs, P. Balakumar
Mechanical and Aerospace Engineering Faculty Research & Creative Works
To Measure Size Distributions of Sub micrometer Aerosols with an Electrical Differential Mobility Analyzer (DMA) Requires an Inversion Procedure. the Knutson (1976) and the Hoppel (1978) Inversion Procedures Were Numerically Investigated for the Case of Log-Normal Aerosol Size Distributions. It Was Found that the Hoppel Procedure Converges to the Same Result as that Given by the Knutson Procedure. the Computational Range for Geometric Mean Diameter (Χg) Was 0.025-0.25 Μm, and for Geometric Standard Deviation (Σg) Was 1.1-2.4. the Inversion Error Was Found to Be Greater Than 10% in Certain "Forbidden Zones" of Χg and Σ …
Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu
Atmospheric Measurements Of Ccn In The Supersaturation Range 0.013-0.681%., Darryl J. Alofs, T. H. Liu
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Concentrations of Cloud Condensation Nuclei in the Atmosphere Were Measured at Rolla, Missouri, Near Ground Level. a Total of 432 Spectra Were Measured over a 10-Month Period. No Consistent Seasonal or Diurnal Pattern Was Observed. Possible Implications for Fogs and Stratus Clouds and for Nuclei Chemical Composition Are Discussed.-From Authorscloud Condensation Nuclei Rolla Missouri Fogs
Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel
Combined Heat And Lass Transfer In Mixed Confection Ower A Horizontal Flat Plate, T. S. Chen, F. A. Strobel
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The combined effects of buoyancy forces from thermal and species diffusion on the heat and mass transfer characteristics are analyzed for laminar boundary layer flow over a horizontal flat plate. The analysis is restricted to processes with low concentration levels such that the interfacial velocities due to mass diffusion and the diffusion-thermo/thermo-diffusion effects can be neglected. Numerical results for friction factor, Nusselt number, and Sherwood number are presented for gases having a Prandtl number of 0.7, with Schmidt numbers ranging from 0.6 to 2.0. In general, it is found that, for the thermally assisting flow, the surface heat and mass …
Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra
Rubber Covered Rolls-The Nonlinear Elastic Problem, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The problem of the indentation of a rubberlike layer bonded to a rigid cylinder and indented by another rigid cylinder is analyzed. The rubberlike layer is assumed to be made of a homogeneous Mooncy-Rivlin material. The materially and geometrically nonlinear problem is solved by using the finite-element code developed by the author. Results computed and presented graphically include the pressure profile at the contact surface, stress distribution at the bond surface and the deformed shape of the indented surface. © 1980 by ASME.
Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr
Nucleation Experiments With Monodisperse Nacl Aerosols., Darryl J. Alofs, M. B. Trueblood, D. R. White, V. L. Behr
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Nucleation Experiments with Monodisperse NaCl Aerosols Showed Good Agreement with the Kohler Theory Relating the Critical Super-Saturation S//c to the Dry Size. Aerosols Produced by Condensing NaCl Showed the Same S//c as Those Produced by Evaporating Aqueous NaCl Solution Droplets. This Indicates that If There is an Energy Barrier in Going from a Dry NaCl Particle to a Solution Droplet, This Energy Barrier is Small. the Fact that the Evaporation Aerosol Particles Are Cubical Crystals and the Condensation Aerosols Are Amorphous Spheres is Shown to Make No Difference in the Nucleation Threshold. the Investigation Also Gives Insights into the Performance …
Performance Of A Dual-Range Cloud Nucleus Counter., Darryl J. Alofs
Performance Of A Dual-Range Cloud Nucleus Counter., Darryl J. Alofs
Mechanical and Aerospace Engineering Faculty Research & Creative Works
An Instrument for Measuring the Concentrations of Cloud Condensation Nuclei as a Function of Nucleus Critical Supersaturation (S//c) is Described. in the Range 0. 1% Less Than Equivalent to S//c Less Than Equivalent to 0. 1%, the Instrument is Operated as a Vertical Flow Thermal Diffusion Chamber. in the Range of 0. 016% Less Than Equivalent to S//c Less Than Equivalent to 0. 1%, the Chamber is Operated at 100% Humidity, and the Equilibrium Radii of the Nuclei Are Measured with an Optical Counter. This Paper Presents a Large Body of Data Taken in the Laboratory to Evaluate the Performance …
Mixed Convection Across A Horizontal Cylinder With Uniform Surface Heat Flux, A. Mucoglu, T. S. Chen
Mixed Convection Across A Horizontal Cylinder With Uniform Surface Heat Flux, A. Mucoglu, T. S. Chen
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Optimal Cantilever Dynamic Vibration Absorbers, R. G. Jacquot, J. Earl Foster
Optimal Cantilever Dynamic Vibration Absorbers, R. G. Jacquot, J. Earl Foster
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This work considers the use of a double-ended cantilever beam as a distributed parameter dynamic vibration absorber applied to a single-degree-of-freedom system in the presence of sinusoidal forces. The problem is analyzed exactly and by an energy approach using a single mode approximation for the cantilever beam. The results for both techniques compare favorably and damping is introduced in the form of a complex beam modulus. Optimal tuning and optimal damping parameters are found for a given ratio of absorber mass to main mass. © 1977 by ASME.
Studies Of Vibrational Surface Modes In Ionic Crystals. I. Detailed Shell-Model Studies For The Unrelaxed (001) Face Of Seven Crystals Having The Rocksalt Structure, T. S. Chen, F. W. De Wette, G. P. Alldredge
Studies Of Vibrational Surface Modes In Ionic Crystals. I. Detailed Shell-Model Studies For The Unrelaxed (001) Face Of Seven Crystals Having The Rocksalt Structure, T. S. Chen, F. W. De Wette, G. P. Alldredge
Mechanical and Aerospace Engineering Faculty Research & Creative Works
We present a comprehensive, unified account of the lattice dynamics of unrelaxed (001) faces of seven crystals having the rock salt structure, three of which have an absolute gap between the acoustical and optical bulk bands (RbF, RbCl, and NaI) and four of which have overlap between these bulk bands (NaF, NaCl, LiF, and MgO). The results are obtained from calculations of the normal modes of a thin crystal film in which the ionic interactions are described by the rigid-shell model. An outline of the formulation of the shell model for the film is given, and the rapid convergence of …
Deformation Produced By A Simple Tensile Load In An Isotropic Elastic Body, R. C. Batra
Deformation Produced By A Simple Tensile Load In An Isotropic Elastic Body, R. C. Batra
Mechanical and Aerospace Engineering Faculty Research & Creative Works
It is shown that a simple tensile load produces a simple extension provided the empirical inequalities (Truesdell and Noll [1], eqn. 51.27) hold. © 1976 Noordhoff International Publishing.
Bit Penetration Into Rock-A Finite Element Study, J. K. Wang, T. F. Lehnhoff
Bit Penetration Into Rock-A Finite Element Study, J. K. Wang, T. F. Lehnhoff
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The sequence of rock failure mechanisms and quantitative information on stress, displacement and material failure in the process of bit penetration have been obtained through computer simulation. A finite element approach has been developed to simulate bit penetration from bit-rock interaction to chip formation. A mathematical rock failure model, based on available rock failure experiments, has been proposed to represent post-failure rock behavior and applied in the penetration simulations. The finite element code was developed for two-dimensional plane strain problems to consider non-linear material properties, geometric non-linearity, and fracture propagation. An anistropic element as well as variable stiffness and stress …
Development Of Helicopter Flight Path Models, Alfred Fermelia, Donald A. Gyorog, V. J. Flanigan
Development Of Helicopter Flight Path Models, Alfred Fermelia, Donald A. Gyorog, V. J. Flanigan
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The objective of this paper is to present general techniques for simulating helicopter flight trajectory response. During flight the pilot manipulates the controls either to trim the helicopter for steady flight by balancing the external forces and moments or to produce a desired maneuver by controlling the unbalance of these forces and moments. Discussions of the physical phenomena involved with the aerodynamics of the rotors and fuselage are given in [1] through [3]. The simulated control function will be composed forward-aft cyclic, lateral cyclic, pedal, and collective. This control will be represented by the vector
Numerical Simulation Of A Widely Used Cloud Nucleus Counter., Darryl J. Alofs, J. C. Carstens
Numerical Simulation Of A Widely Used Cloud Nucleus Counter., Darryl J. Alofs, J. C. Carstens
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The Performance of the Conventional Horizontal Plate Thermal Diffusion Chamber as a Cloud Nucleus Counter Was Studied. Numerical Calculations Were Performed in Order to Follow the Simultaneous Drop Growth and Sedimentation in the Spatially and Temporally Nonuniform Supersaturation Field. the Effect of Nuclei Distribution and Smallest Detectable Drop Size Were Investigated. the Results Indicate Order of Magnitude Uncertainty in the Count at 0. 1% Supersaturation, and a Factor of 2 Uncertainty at 1. 0% Supersaturation.
A Closed-Form Solution For The Radiosity At The Edge Of A Rectangular Cavity, Alfred L. Crosbie
A Closed-Form Solution For The Radiosity At The Edge Of A Rectangular Cavity, Alfred L. Crosbie
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Mie Scattering Computations For Moderately Large Spherical Particles, Dwight C. Look
Mie Scattering Computations For Moderately Large Spherical Particles, Dwight C. Look
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Predicting Natural Frequencies Of A Hydrodynamically Lubricated Journal Bearing With Constant Oil Supply Pressure, D. C. Edwards, N. Khorzad, Charles L. Edwards
Predicting Natural Frequencies Of A Hydrodynamically Lubricated Journal Bearing With Constant Oil Supply Pressure, D. C. Edwards, N. Khorzad, Charles L. Edwards
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The analytical and experimental investigations reported here deal with the natural frequencies and system behavior of a full journal bearing subjected to a small sinusoidal load superimposed on a large unidirectional static load. The analysis, verified by experimentation, shows that the bearing can be regarded as two independent second-order systems acting perpendicular to each other. The variable coefficients of the equations of motion cause the bearing to behave as an underdamped system for low values of static eccentricity ratio to, and as an overdamped system for intermediate values of to. The bearing tends to be unstable above a particular to. …
The Effects Of Main-Flow Radial Velocity On The Stability Of Developing Laminar Pipe Flow, F. C.T. Shen, T. S. Chen, L. M. Huang
The Effects Of Main-Flow Radial Velocity On The Stability Of Developing Laminar Pipe Flow, F. C.T. Shen, T. S. Chen, L. M. Huang
Mechanical and Aerospace Engineering Faculty Research & Creative Works
In studying the stability due to axisymmetric disturbances of the developing flow of an incompressible fluid in the entrance region of a circular tube, a generalized version of the Orr-Sommerfeld equation was derived which takes account of the radial velocity component in the main flow. The new terms in the generalized Orr-Sommerfeld equation are inversely proportional to the Reynolds number. The resulting eigenvalue problem consisting of the disturbance equation and the boundary conditions was solved by a direct numerical integration scheme along with an iteration procedure. Neutral stability curves and critical Reynolds numbers at various axial locations are presented. A …
Transport Phenomena In Thermally Stratified Boundary Layers, D. W. Pepper, S. C. Lee
Transport Phenomena In Thermally Stratified Boundary Layers, D. W. Pepper, S. C. Lee
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Studies of heat, mass, and momentum transfer are made to analyze the formation of marine fogs in thermally stratified boundary layers in the atmosphere. The governing partial differential equations of continuity, momentum, temperature, and concentration are used to describe the transport phenomena. An additional equation of turbulence energy is introduced to account for the development of the turbulent motions. Simultaneous solution of this system of equations allows the turbulent exchange coefficients to be treated in the same way as all other dependent parameters. Verification of the theoretical approach is made by comparing the numerical predictions with wind tunnel simulations of …
Thermal Stresses In A Sphere Due To Local Heating Followed By Complete Cooling, T. S. Chen, K. Thirumalai, J. B. Cheung
Thermal Stresses In A Sphere Due To Local Heating Followed By Complete Cooling, T. S. Chen, K. Thirumalai, J. B. Cheung
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Measurement Of Growth Rate To Determine Condensation Coefficients For Water Drops Grown On Natural Cloud Nuclei., A. M. Sinnarwalla, Darryl J. Alofs, J. C. Carstens
Measurement Of Growth Rate To Determine Condensation Coefficients For Water Drops Grown On Natural Cloud Nuclei., A. M. Sinnarwalla, Darryl J. Alofs, J. C. Carstens
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Growth Rate Measurements Were Made for Water Drops Grown on Nuclei in Atmospheric Air Samples Taken in Rolla, Missouri. Rolla, Having a Population of 15,000 and Very Little Industry, is Relatively Free of Urban Pollutants. the Measurements Were Made in a Vertical Flow Thermal Diffusion Chamber at Supersaturations of 0. 5 and 1%. the Time to Grow from Near Dry Radius to the Final Radius (6 to 7. 5 Mu M) Was Measured. If One Assumes the Thermal Accomodation Coefficient is Unity, the Measurements Indicate an Average Value of 0. 026 for the Condensation Coefficient. the Temperature Ranged from 22. …
Insoluble Condensation Nuclei: The Effect Of Contact Angle, Surface Roughness And Adsorption., P. C. Mahata, Darryl J. Alofs
Insoluble Condensation Nuclei: The Effect Of Contact Angle, Surface Roughness And Adsorption., P. C. Mahata, Darryl J. Alofs
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Condensation of Water Vapor on Various Surfaces Was Studied Experimentally. for Surfaces with an Air-Water Contact Angle Theta Less Than 20 Degree, the Experimentally Determined Values of Critical Supersaturation S//c Agreed with Those Given by the Volmer Theory. at Higher Theta, the Experimental Values of S//c Were Below the Volmer Theory Values. When the Applied Supersaturation Was Less Than S//c, Condensation Was Avoided for Periods as Long as 20 H. It Was Determined Both by Experiment and Theoretical Analysis that the Effect of Surface Roughness is to Decrease S//c Only Slightly. These Results Suggest that Most Insoluble Airborne Particles Are …
The Application Of Impact Dampers To Continuous Systems, Ranjit K. Roy, Richard D. Rocke, J. Earl Foster
The Application Of Impact Dampers To Continuous Systems, Ranjit K. Roy, Richard D. Rocke, J. Earl Foster
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A study has been made of the application of impact dampers to two types of continuous systems, a simply supported and a clamped beam. Experimental models were tested in the laboratory and computer programs were developed to calculate response by two separate approaches. Results from calculations agreed favorably with experimental tests. Curves presented show the response to be expected for values of significant system parameters and enable the user to apply impact dampers to these types of continuous systems. © 1975 by ASME.