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Articles 511 - 540 of 708
Full-Text Articles in Engineering
On The Flow Near An Enclosed Rotating Blade In The Neighborhood Of The Ground, Tze-Lien Liang
On The Flow Near An Enclosed Rotating Blade In The Neighborhood Of The Ground, Tze-Lien Liang
Masters Theses
"The flow in the vicinity of an enclosed rotating blade near the ground was studied both analytically and experimentally. Experimental results were obtained by making pitot tube traverses across the face of the housing but gave only a qualitative indication of the velocity distribution. Tufts of strings were used to locate the flow directions in the vicinity of the ground and the housing. The two dimensional potential flow solution was found to yield unreasonable results for this flow configuration due to viscous and rotative effects. The three-dimensional Navier-Stokes equations were solved numerically by using the successive underrelaxation method. The results …
Ionization Of Air Produced By Strong Shocks, Howard Sajon Joyner
Ionization Of Air Produced By Strong Shocks, Howard Sajon Joyner
Doctoral Dissertations
"This dissertation provides theoretical predictions along with experimental results for electron concentrations behind a shock as a function of Mach number over a range from 11 to 20 using a combustion driven shock tube operating in air. These theoretical predictions represent an upper bound for chemical equilibrium. The model for air was 78.0880% nitrogen, 20.949% oxygen, 0.0300% carbon dioxide, 0 .9300% argon, 0.0025%neon, and 0.0005% helium. Also the theory of a double diaphragm shock tube with corresponding pressure ratio vs. Mach number relationships is provided. A computor [sic] program using iterative techniques for a succinct presentation covering the modifications and …
Use Of The Turbulence Kinetic Energy Equation In Prediction Of Nonequilibrium Turbulent Boundary Layers, William Madison Byrne Jr.
Use Of The Turbulence Kinetic Energy Equation In Prediction Of Nonequilibrium Turbulent Boundary Layers, William Madison Byrne Jr.
Doctoral Dissertations
"A differential method is proposed for the prediction of a broad range of turbulent boundary layers of engineering and scientific interest. A digital computer program is presented which is applicable to boundary layers with positive, negative, and zero pressure gradient in the main-stream direction as well as boundary layers with suction, blowing or zero mass addition at the wall. The turbulence kinetic energy equation is solved simultaneously with the longitudinal momentum and continuity equations to provide an independent means for determining the effective viscosity which makes allowance for "history" effects in the flow. It is shown that the prediction method …
Optimizing Diesel Engine Efficiency Using The Controllability Of A Variable Ratio Hydrostatic Transmission, Gordon Wright
Optimizing Diesel Engine Efficiency Using The Controllability Of A Variable Ratio Hydrostatic Transmission, Gordon Wright
Doctoral Dissertations
"A linear mathematical model of a diesel engine, hydrostatic transmission, and electric dynamometer system was developed. This model was used as an aid in designing a single input controller which regulates engine speed to optimize efficiency while maintaining constant transmission output speed under changing load conditions. Compensation was necessary to stabilize the system because of positive feedback in the engine control system. The compensated system's response was compared to that which was predicted analytically. The analytical model was then extended to design the control system parameters to operate the engine and transmission in a representative vehicle"--Abstract, page ii.
Linear Analysis Of Pneumatic Dashpot Damping, Nathalal Gordhanbhai Patel
Linear Analysis Of Pneumatic Dashpot Damping, Nathalal Gordhanbhai Patel
Masters Theses
"The linear analysis of pneumatic damping with orifice or capillary restrictions and with or without mean flow is presented. Temperature and pressure relationships are derived from energy considerations rather than the usual simplification of an assumed polytropic coefficient. Analytical results are compared with the experimental results and a coefficient of heat transfer, Ch, is defined for calculation of the equivalent linear damping factor Cd"--Abstract, page ii.
Heat Transfer Through A Spherical Gas Shell, Adel Nassif Saad
Heat Transfer Through A Spherical Gas Shell, Adel Nassif Saad
Masters Theses
"The radiative transfer through an absorbing-emitting gas shell contained within black concentric spheres at uniform but different temperatures was investigated. A close form exact solution and an approximate solution were derived for the case of isothermal gas layer. The two solutions appear to compare well specially at low diameter ratios, and both agree with the radiative equilibrium solution in the thin limit. An approximate method was developed for the radiative equilibrium, non-isothermal gas layer, of the above problem. The method is based on the assumption of a hyperbolic emissive power distribution through the gas shell. The jump boundary conditions were …
Numerical Solutions Of The Torsional Oscillations Of A Shaft-Flywheel System, Mahendrakumar Ramkrishna Patel
Numerical Solutions Of The Torsional Oscillations Of A Shaft-Flywheel System, Mahendrakumar Ramkrishna Patel
Masters Theses
"The application of the finite-difference technique, the Fourier transform, and the Laplace transform for the solution of a system governed by the one-dimensional wave equation is examined. A specific example consisting of a continuous shaft-flywheel system acted upon by an exciting torque applied at a specific section of the shaft is studied. The exact solution to this example is obtained using the classical method of superposition of modes, and is used as a reference to evaluate the accuracy (in terms of the rms error) and relative efficiency (based on computer time) of three approximate solution methods. A sinusoidal excitation was …
A Digital Computer Program For Studying Elasto-Plastic Structural Behavior Due To Cyclic Loading, Rameshchandra Chandulal Hazariwala
A Digital Computer Program For Studying Elasto-Plastic Structural Behavior Due To Cyclic Loading, Rameshchandra Chandulal Hazariwala
Masters Theses
"A computer program has been developed to study the behavior of plane stress structures under cyclic loading. Such phenomena as thermal ratcheting, alternate plasticity, shake-down and the Bauschinger effect may be considered. The incremental theory of plasticity has been used. The program deals with realistic conditions such as nonlinear strain hardening, nonlinear temperature distribution and occurrence of both compressive and tensile plastic flow. The concept of an average material property has been used. Thermal ratcheting of a beam subjected to a constant bending moment and a temperature cycle has been studied in detail. The analysis shows analytically that the rate …
A Transient Method Of Negligible Internal Thermal Resistance For Determining Thermal Contact Conductance In A Vacuum, Richard Chuka Oboka
A Transient Method Of Negligible Internal Thermal Resistance For Determining Thermal Contact Conductance In A Vacuum, Richard Chuka Oboka
Masters Theses
"A transient method for experimentally determining the interface conductance between metallic surfaces in contact is developed. The method applies the theory of negligible internal thermal resistance of one of the materials which form the interface. The method is applicable when the interface conductance is very low, a situation which exists when low conductance interstitial materials are used between contacting surfaces for purposes of thermal isolation. In this investigation, stainless steel wire screens of 10 and 100 mesh were used as interstitial materials between aluminum surfaces in a vacuum environment of 10⁻⁵ to 10⁻⁶ Torr. The interface pressure ranged from 40 …
Effect Of Surface Conditions On Nucleate Pool Boiling Of Refrigerant-11, Abbas M. Sinnarwalla
Effect Of Surface Conditions On Nucleate Pool Boiling Of Refrigerant-11, Abbas M. Sinnarwalla
Masters Theses
"The purpose of this investigation was to determine the effect of surface conditions on the heat transfer for nucleate pool boiling from flat horizontal surfaces. Experiments were carried out using Refrigerant-11 at atmospheric pressure as the test fluid with Inconel-600 as the heater material. The heat transfer coefficient was determined for mirror finished, chemically etched, glass beaded and sandpaper roughened heater surfaces over heat flux ranging for 0 to 18000 BTU/HR SQ FT. At a given heat flux, the heat transfer coefficient was found to be the lowest for mirror finished surface and the highest for sandpaper roughened surface"--Abstract, page …
The Closed Cycle-External Combustion Engine And Air Pollution, Galen Lee Pearson
The Closed Cycle-External Combustion Engine And Air Pollution, Galen Lee Pearson
Masters Theses
"The impact of the internal combustion engine on the air pollution problem in this country was presented and alternative propulsion systems for the land transportation vehicle were investigated. The potential characteristics of the more promising closed cycle-external combustion engine concepts were established and discussed. The closed thermodynamic power cycles analyzed include the Rankine, Stirling, and Feher supercritical cycles. Thermodynamic property data on eighteen candidate working fluids for the Rankine and Feher supercritical power cycles have been assembled and were presented in a utilizable form. The thermal efficiency (ratio of the net work out to the heat input) and the many …
Measurement Of Thermal Accommodation Coefficients Of Steel Surfaces, Wing On Ho
Measurement Of Thermal Accommodation Coefficients Of Steel Surfaces, Wing On Ho
Masters Theses
"The thermal accommodation coefficient plays an important role in low density thermal energy transfer measurement. The object of this investigation was to measure the thermal energy transfer between a heated test surface and a water cooled reference surface (flat black lacquer) consisting of two infinite concentric cylinders separated by dry air. Two machined and sanded steel cylinders with mean surface roughnesses of 25 microinches and 7.5 microinches were used as the test surfaces . Measurements were made in the pressure range of 1.2 x 10⁻⁶ mm Hg. to 1.8 x 10⁻⁶ mm Hg. and temperature range for test cylinders of …
Magnetohydrodynamic Channel Flow With Non-Uniform Inlet Velocity Profiles, Gwok-Liang Chen
Magnetohydrodynamic Channel Flow With Non-Uniform Inlet Velocity Profiles, Gwok-Liang Chen
Masters Theses
"An analysis is made of laminar magnetohydrodynamic (MHD) flow development in the entrance region of a parallel-plate channel. The problem is formulated in general for any velocity distribution at the channel inlet by extending the linearization method of Sparrow, Lin, and Lundgren for non-MHD duct flows. This method involves linearization of the inertia terms in the equation of motion by introducing a stretched axial coordinate. A closed form solution is obtained for the velocity distributions which are continuous across the channel and along the length all the way from the entrance to the fully developed region. An expression for the …
Evaluation Of Cascaded Inertial Vibration Isolation Systems, Rajnikant Bhikhabhai Patel
Evaluation Of Cascaded Inertial Vibration Isolation Systems, Rajnikant Bhikhabhai Patel
Masters Theses
"Cascaded inertial vibration isolation systems are examined in this report. Systems employing one, two or three masses in series on isolators are investigated. The objective is to determine if the cascaded systems have appreciable advantages over the classical single mass system. The equations of motion for these systems are derived by applying Newton's second law of motion. The homogeneous and steady state sinusoidal excitation solutions have been established. Transmissibility of forces and moments to the foundation has been obtained for several cases of force excitation. Comparisons of the cases investigated are based upon the principal mode frequencies, mode shapes, center …
A Theoretical Analysis Of The Free Vibrations Of A Clamped Circular Plate With Damping, Bhalchandra Krishnaji Vaidya
A Theoretical Analysis Of The Free Vibrations Of A Clamped Circular Plate With Damping, Bhalchandra Krishnaji Vaidya
Masters Theses
"A theoretical analysis of the free vibrations of a clamped circular plate was undertaken. The effects of transverse shear were considered for application to relatively thick plates in which there exist sharp transients and frequencies corresponding to higher modes. The method adopted by R. D. Mindlin was used to develope [sic] the differential equation of motion for the plate. The damping effect due to the resistance of the medium in which the plate vibrates was also considered. This damping was assumed to be due to the generation of pressure waves caused by the displacement of the plate...Since the solution requires …
Experimental Determination Of Dynamic Properties Of Aluminum Including Poisson's Ratio, Terry Lee Holman
Experimental Determination Of Dynamic Properties Of Aluminum Including Poisson's Ratio, Terry Lee Holman
Masters Theses
"Two rods of 7075-T651 aluminum are longitudinally impacted to investigate the material's dynamic properties. The test rod, initially at rest, is instrumented with strain gages to record the strain-time history after the impact rod, accelerated to uniform velocity by an air gun launcher, strikes the test rod. A camera records the strain-time pattern displayed on an oscilloscope. The experiment indicates a consistent rise time of approximately 9 µsec. Simple one-dimensional theory correlates well with the experimental data. Compensation is included for the transverse sensitivity of the gages used. The dynamic values for both the modulus of elasticity and Poisson's ratio …
A Finite Element Method For Geometrically Nonlinear Large Displacement Problems In Thin, Elastic Plates And Shells, Ronald August Melliere
A Finite Element Method For Geometrically Nonlinear Large Displacement Problems In Thin, Elastic Plates And Shells, Ronald August Melliere
Doctoral Dissertations
"A finite element method is presented for geometrically nonlinear large displacement problems in thin, elastic plates and shells of arbitrary shape and boundary conditions subject to externally applied concentrated or distributed loading. The initially flat plate or curved shell is idealized as an assemblage of flat, triangular plate, finite elements representing both membrane and flexural properties. The 'geometrical' stiffness of the resulting eighteen degree-of-freedom triangular element is derived from a purely geometrical standpoint. This stiffness in conjunction with the standard small displacement 'elastic' stiffness is used in the linear-incremental approach to obtain numerical solutions to the large displacement problem. Only …
The Analysis Of R-S-S-R Spatial Four-Bar Mechanism, David Perng Chyi
The Analysis Of R-S-S-R Spatial Four-Bar Mechanism, David Perng Chyi
Masters Theses
"Although many methods are known for the kinematic analysis of spatial mechanisms, such as descriptive geometry, vector analysis, dual number theory, matrices, screw calculus, and various other methods, a better way to analyze the specific R-S-S-R four-bar mechanism is to use tensor methods in order to eliminate the apparently formidable and tedious tasks of mathematically formulating problems and obtaining solutions. The analysis described in this paper is developed basically by using tensor notations and operations, and the calculations take advantage of the capabilities of modern digital computers. A FORTRAN program for the IBM 360 Data Processing System which will analyze …
Method For Optimizing Multi-Layer Insulation, William Donald Morath
Method For Optimizing Multi-Layer Insulation, William Donald Morath
Masters Theses
"The use of multi-layer insulation can result in reduced material cost, weight, or volume. A method for selecting layer materials is described. Each layer material is selected to operate at its upper temperature limit and to contribute to the overall performance of the wall. The analyses required for optimizing flat and cylindrical walls are developed. Use of the digital computer makes it feasable [sic] to select layer materials from a large group of candidates. Fortran IV programs for optimizing flat and cylindrical walls are presented, and their use is demonstrated by the solution of example problems. Methods for improving the …
Film Boiling From Inclined Flat Surfaces, Charles Ernest Price
Film Boiling From Inclined Flat Surfaces, Charles Ernest Price
Masters Theses
"The object of this investigation was to determine the effect of inclination on the heat transfer for saturated film pool boiling from a flat plate heater. Nitrogen at atmospheric pressure was used as the test fluid. The test plate was oriented at various angles from the horizontal position and the convective film coefficient was determined for each angle. Tests were conducted for heater angles of 0°, 30°, 60°, and 90°. The heater strip was placed in a container of the liquid and was heated electrically. Heat transfer results were obtained for plate temperatures ranging from 100 to 800°F. As the …
Apparatus And Techniques For The Plane Wave Analysis Of Acoustic Filters, Victor Hugo Simon
Apparatus And Techniques For The Plane Wave Analysis Of Acoustic Filters, Victor Hugo Simon
Masters Theses
"This thesis describes a method for determining the reflection and transmission characteristics of acoustic filters under static (i.e. no flow) conditions. These characteristics are obtained by the combination of linear plane wave acoustic theory with a sequential experimental procedure. The experimental data necessary for the calculation of the reflection characteristics were obtained from measurements made on the inlet side of the filter with a standing wave tube apparatus. In order to calculate the transmission characteristics of the filter, the standing wave measurements were augmented with measurements taken on both the inlet and outlet side of the filter. This was accomplished …
A Computerized Method For Finding The Dynamic Response Of Multi-Mass Systems With Damping To Arbitrary Inputs, Bakulesh Balbhadra Patel
A Computerized Method For Finding The Dynamic Response Of Multi-Mass Systems With Damping To Arbitrary Inputs, Bakulesh Balbhadra Patel
Masters Theses
"A practical procedure for the systematic application of Foss's method to the solution of multi-degree-of-freedom damped systems is presented. It is relatively easy to determine the response of classically damped systems to various inputs. For non-classically damped systems the method proposed by K. A. Foss has been employed. This method gives an exact and complete solution for the response of linear multi-mass damped systems subjected to arbitrary inputs. Since the method requires lengthy and complex computations, the use of a digital computer is essential. In order to obtain the complete response of a multi-mass damped system to both sinusoidal and …
A Comparison Of Lumped Parameter Models Commonly Used To Describe One-Dimensional Vibration Problems, Suresh Kumar Tolani
A Comparison Of Lumped Parameter Models Commonly Used To Describe One-Dimensional Vibration Problems, Suresh Kumar Tolani
Masters Theses
"Three lumped parameter model representations of the one-dimensional uniform continuous system in a vibration state are examined. The exact (continuous) solutions were used as a reference to evaluate the accuracy of the results obtained via these discrete element models. The model comparisons, carried out for both the principal modes and the systems under forced excitations, are based on the maximum strain energy. The effect of varying the number of segments in the model representation showed improvement in approximating the exact strain energy solution as the number of segments was increased. In general, the results of the model comparisons based on …
Dynamic Response Of A Gyrocompass, Subhash Govind Kelkar
Dynamic Response Of A Gyrocompass, Subhash Govind Kelkar
Masters Theses
"A gyrocompass with three degrees of freedom is studied and an attempt made to solve the exact equations of motion numerically. The equations are obtained by using the Lagrange formulation of the problem. The kinetic energy and the potential energy of the system are determined from the energies of the various components. These are then substituted into Lagrange's equation to obtain the three equations of motion for the three angular coordinates. As few restrictive assumptions as possible are made during this development. From these exact equations of motion an approximate analytical solution is obtained by making several assumptions and then …
The Use Of Turbulence Energy Equation In Boundary Layer Study, Ro-Chi Tai
The Use Of Turbulence Energy Equation In Boundary Layer Study, Ro-Chi Tai
Masters Theses
"A turbulent boundary layer problem has been studied analytically and compared with an available experiment in the literature. Correlations of the experimental data were made to investigate the validity of the commonly used empirical relations on turbulent shear stresses. It was found that the model which related the local turbulent shear stress linearly with the local turbulent kinetic energy, as used by Bradshow et. al., appeared to be most reasonable. combining this model with the expression of turbulent viscosity given by Boussinesq, it was then possible to introduce the turbulence-energy equation in addition to the governing equations of continuity and …
Design Of R-C-C-R Spatial Mechanism, Kao-Chien Hsei
Design Of R-C-C-R Spatial Mechanism, Kao-Chien Hsei
Masters Theses
"An analysis to design a particular R-C-C-R spatial mechanism was developed using tensor notations and operations. This specific R-C-C-R spatial mechanism can be used to couple two shafts intersected at a skew angle with constant rotating speed ratio. This skew angle, or bending angle of the two shaft, may vary from 30 up to 180 degrees. The governing equations of relative positions of the mechanism were formulated as a function of two variables: the bending angle of the shafts and the rotating angle of the input link. To exemplify the various design conditions, the design parameter versus the bending angle …
Dynamic Response Of Circular Plates To Transient And Harmonic Transverse Loads Including The Effect Of Transverse Shear And Rotary Inertia, Perakatte Joseph George
Dynamic Response Of Circular Plates To Transient And Harmonic Transverse Loads Including The Effect Of Transverse Shear And Rotary Inertia, Perakatte Joseph George
Doctoral Dissertations
"Using an improved theory of plate vibration suggested by R. D. Mindlin which takes into account the effects of transverse shear and rotary inertia, free and forced transverse vibrations of uniform circular plates are studied and the results compared with those obtained using the classical theory of plate vibration. The governing equations are developed in polar coordinates using the equations of elasticity. Frequency equations for axisymmetric and antisymmetric vibrations are derived for solid circular plates under different boundary conditions and for an annular plate rigidly mounted on a shaft. The response of plates to different types of rapidly applied axisymmetric …
Analysis Of A Water Level Control, Bhupendra Girdharlal Shah
Analysis Of A Water Level Control, Bhupendra Girdharlal Shah
Masters Theses
"This thesis presents the analysis of a controller for a liquid level control system. The controller was built using an analog computer providing the ability to easily construct up to three modes of control. The controllers analyzed were: 1.) Proportional, 2.) Proportional plus reset, and 3.) Proportional plus reset plus preact. The system was tuned experimentally to provide satisfactory operation and root loci were also plotted to show the system stability for the three modes"--Abstract, page ii.
The Design Of A Direct Current Generator Field Controller, Melvyn Elwin Downs
The Design Of A Direct Current Generator Field Controller, Melvyn Elwin Downs
Masters Theses
"A controller was built utilizing transistors and silicon controlled rectifiers to allow torque control of the General Electric dynamometer, type TLC-50. The current gain of the controller was approximately 10⁶ such that the field current could be controlled by an input current of zero to approximately two microaaperes. The transfer function for the controller-dynamometer system was experimentally determined. The results indicate that the gain of the open loop torque control system is constant for frequencies up to 1.1 radians per second. Satisfactory values of gain for proportional and proportional plus integral control, were experimentally determined by operating the closed loop …
Application Of Approximate Transmission Matrices To Describe Transverse Beam Vibrations, Ranjit Kumar Roy
Application Of Approximate Transmission Matrices To Describe Transverse Beam Vibrations, Ranjit Kumar Roy
Masters Theses
"This paper is a report of an investigation of an approximate method for finding the principal mode frequency roots for beams in transverse vibration. The method utilizes approximate transmission matrices obtained by a power series expansion of the basic differential equation which governs the transmission matrix. Investigation has been carried out to examine the efficiency of the method in producing the first several normal mode frequency roots. This has been achieved by applying the method to several uniform and non-uniform beams and comparing the results with the exact solutions. The technique has further been applied to non-uniform beams of tapered …