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Articles 751 - 780 of 799
Full-Text Articles in Engineering
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 …
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 …
Multiple High Voltage Output Dc-To-Dc Power Converter, Don Cronin, Bertrand F. Farber, Hartmut K. Gehm, Daniel S. Goldin
Multiple High Voltage Output Dc-To-Dc Power Converter, Don Cronin, Bertrand F. Farber, Hartmut K. Gehm, Daniel S. Goldin
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Disclosed is a multiple output DC-to-DC converter. The DC input power is filtered and passed through a chopper preregulator. The chopper output is then passed through a current source inverter controlled by a squarewave generator. The resultant AC is passed through the primary winding of a transformer, with high voltages induced in a plurality of secondary windings. The high voltage secondary outputs are each solid-state rectified for passage to individual output loads. Multiple feedback loops control the operation of the chopper preregulator, one being responsive to the current through the primary winding and another responsive to the DC voltage level …
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.
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 …
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.
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.
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 …
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. …
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
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 …
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.
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.
Transient Thermal Stresses In A Sphere By Local Heating, J. B. Cheung, T. S. Chen, K. Thirumalai
Transient Thermal Stresses In A Sphere By Local Heating, J. B. Cheung, T. S. Chen, K. Thirumalai
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The problem of transient thermal stresses in a solid, elastic, homogeneous, and isotropic sphere is solved for uniform and nonuniform, local surface heating. The temperature solutions are obtained by using separation of variables and integral transformation. The corresponding thermal stresses are derived by superposing a particular displacement potential function on Boussinesq solutions. Numerical solutions for two particular cases of localized heating of a typical brittle spherical solid have been obtained and presented. The results indicate a tensile stress concentration in the interior of the solid below the heated zone. © 1974 by ASME.
Vibration Characteristics Of Free Thin Cylindrical Shells, Floyd M. Cunningham, D. E. Leanhardt
Vibration Characteristics Of Free Thin Cylindrical Shells, Floyd M. Cunningham, D. E. Leanhardt
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This paper considers the flexural vibrations of free thin circular cylinders. A frequency equation is derived using free-free characteristic beam functions to represent the variation of mid-surface shell displacement components, u, v and w, with respect to the axial direction. Timoshenko strain-displacement relations for thin cylinders are used to determine elastic vibratory strain energy. Energy methods are applied to obtain the frequency equation and associated amplitude ratios for each of its roots. This energy solution is checked experimentally using a vibration exciter and numerically using the SABOR IV finite element program. With minor modification, the frequency equation conforms to the …
Engineering And Scientific Manpower- A Scarce Resource For The 1970'S, Merl Baker
Engineering And Scientific Manpower- A Scarce Resource For The 1970'S, Merl Baker
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Nonequilibrium Structure Of Argon Shock Waves, Harlan F. Nelson
Nonequilibrium Structure Of Argon Shock Waves, Harlan F. Nelson
Mechanical and Aerospace Engineering Faculty Research & Creative Works
This theoretical study investigates the influence of (1) the nonequilibrium excited state population in the relaxation region and (2) line radiation in the precursor on shock wave structure by considering strong shock waves propagating at Mach 18 and 24 into a theoretical argon-like gas at a pressure of 1 cm Hg and a temperature of 300°K. The argon atom is modeled as having two bound states plus a continuum, and the calculations include finite atom-atom and electron-atom collisional ionization and excitation rates as well as continuum and line radiation. The electron gas is allowed to be at a different temperature …
Breakdown Of The Laminar Flow Regime In Permeable-Walled Ducts, E. M. Sparrow, G. S. Beavers, T. S. Chen, J. R. Lloyd
Breakdown Of The Laminar Flow Regime In Permeable-Walled Ducts, E. M. Sparrow, G. S. Beavers, T. S. Chen, J. R. Lloyd
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The stability of laminar flow in a parallel-plate channel having one permeable bounding wall is investigated by means of linear theory. The analysis lakes account of the coupling of the disturbance, fields in the channel and in the permeable material and of velocity slip at the surface of the permeable wall. Complementary experiments are performed in which the breakdown of the laminar regime in flat rectangular ducts is identified from pressure-drop measurements and from flow visualization studies. The experiments cover the range of slip velocities from 15-30 percent of the mean velocity and, in addition, the case of zero slip …
Decision-Directed Detector For Overlapping Pcm/Nrz Signals, Cheng Wang, Thomas L. Noack
Decision-Directed Detector For Overlapping Pcm/Nrz Signals, Cheng Wang, Thomas L. Noack
Mechanical and Aerospace Engineering Faculty Research & Creative Works
A decision-directed (DD) technique for the detection of overlapping PCM/NRZ signals in the presence of white Gaussian noise is investigated. The performance of the DD detector is represented by probability of error PE versus input signal-to-noise ratio (SNR). To examine how much improvement in performance can be achieved with this technique, PE's with and without DD feedback are evaluated in parallel. Further, analytical results are compared with those found by Monte Carlo simulations. The results are shown in good agreement. © 1973, IEEE. All rights reserved.
An Experimental And Numerical Study Of Elastic Strain Waves On The Center Line Of A 6061-T6 Aluminum Bar, J. L. Habberstad, K. G. Hoge, J. Earl Foster
An Experimental And Numerical Study Of Elastic Strain Waves On The Center Line Of A 6061-T6 Aluminum Bar, J. L. Habberstad, K. G. Hoge, J. Earl Foster
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The elastic strain waves resulting from the impact of two 3/4-in-dia 6061-T6 aluminum bars are studied experimentally and analytically. Experimental data are obtained from strain gages on the center line and outer surface of the bar, located at various distances from the impact end of the bar. Experimental data are compared to numerical results obtained from integrating the exact equations of two-dimensional motion. In general, agreement between the numerical and experimental results is very good. © 1972 by ASME.
An Application Of Bubble Shape Theory To The Determination Of Air Transfer Through Adsorbed Surface Films, Robert A. Medrow
An Application Of Bubble Shape Theory To The Determination Of Air Transfer Through Adsorbed Surface Films, Robert A. Medrow
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
A Strain Energy Comparison Of Discrete Modeling For Vibrating Continuous Systems, S. K. Tolani, Richard Dale Rocke
A Strain Energy Comparison Of Discrete Modeling For Vibrating Continuous Systems, S. K. Tolani, Richard Dale Rocke
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Lumped parameter models commonly used to describe continuous one-dimensional and Bernoulli-Elder beam vibration problems have been compared on the basis of maximum system, strain energy. The consistent mass matrix approach has been included in the comparison. Standard matrix techniques have been employed to mathematically obtain desired solutions. Closed form solutions and solutions via the models to Ike system strain energy were obtained for all systems in three dynamic states: Free vibrations, constant base acceleration, and half sine base acceleration. Behavior of the strain energy errors, in general, were found to be similar to those of the frequency root errors. © …
Magnetohydrodynamic Stability Of The Developing Laminar Flow In A Parallel-Plate Channel, T. S. Chen, T. E. Eaton
Magnetohydrodynamic Stability Of The Developing Laminar Flow In A Parallel-Plate Channel, T. S. Chen, T. E. Eaton
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Linear stability of the developing laminar flow of an electrically conducting, incompressible fluid in a parallel-plate channel under a transverse magnetic field is investigated. The case of small magnetic Reynolds numbers is treated. The developing flows whose stability characteristics are studied correspond to those induced by a uniform and a parabolic velocity distribution at the channel inlet. The stability of the fully developed Hartmann flow is also reexamined. Neutral stability curves and axial variations of the critical Reynolds number are presented for a range of Hartmann numbers between 0 and 4. It is found that for Hartmann numbers larger than …
Reply To The Comments Of H. M. Princen [2], Robert A. Medrow, B. T. Chao
Reply To The Comments Of H. M. Princen [2], Robert A. Medrow, B. T. Chao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
No abstract provided.
Forming Of 7075-T6 Aluminum In High Pressure Environments, Richard L. Pendleton, Robert L. Davis
Forming Of 7075-T6 Aluminum In High Pressure Environments, Richard L. Pendleton, Robert L. Davis
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Plates of 7075-T6 Aluminum have been folded along a major axis in pressure environments of atmospheric, 20,000 psi, and 40,000 psi. A finite element computer program is used to determine the stress state in the plates at various loads. Tension and compression tests conducted in pressure environments up to 70,000 psi were used to construct models using effective stress, effective strain, and pressure as parameters to predict the behavior of the material under various stress conditions. A prediction of the occurrence of fracture in the folded plate was possible using the computer results and the pressure dependent model. As better …