Rails on Elastic Foundations Under the Influence of High-Speed Traveling Loads

1953 ◽  
Vol 20 (1) ◽  
pp. 13-22
Author(s):  
H. E. Criner ◽  
G. D. McCann
Keyword(s):  
High Speed ◽  
Narrow Range ◽  
Analog Computer ◽  
Point Load ◽  
Specific Design ◽  
Computer Technique ◽  
Elastic Foundations ◽  
Constant Magnitude ◽  
Electric Analog ◽  
Track Beam

Abstract This paper presents an electric-analog-computer technique for the analysis of beams on elastic foundations that are subjected to traveling loads. This method is applicable to the study of such conditions as nonuniform beams, load magnitude and velocity variations, and such nonlinear conditions as the beam leaving contact with the foundation for upward deflections. A general set of dimensionless solutions is presented for the specific case of a point load of constant magnitude and velocity traveling over an infinite uniform linear track beam. These show high values of deflection and moment for a rather narrow range of velocity above and below the critical velocities producing peak disturbances. It was found that quite high accelerations are required to produce significantly less disturbance than in the constant velocity case. A range of nonlinear track-bouncing conditions was studied in connection with a specific design problem. For none of these cases could more severe conditions be produced than indicated by the linear solutions.

A Hybrid Electromechanical Analog Computer Technique for Optimizing Vibration Systems

1972 ◽  
Vol 94 (2) ◽  
pp. 381-387 ◽  
Author(s):  
S. F. Masri ◽  
A. M. Ibrahim
Keyword(s):  
Simulation Method ◽  
Analog Computer ◽  
Design Parameters ◽  
Clearance Ratio ◽  
Computer Technique ◽  
Impact Damper ◽  
Time Simulation ◽  
Electric Analog ◽  
Vibration Problems ◽  
The Impact

A simple and efficient real-time simulation method is presented for investigating certain classes of vibration problems by employing a hybrid electro-mechanical analog computer. This approach combines the efficiency of electric-analog techniques with the advantages of using actual mechanical components to generate “genuine” functions that are not known or not well defined analytically. The response of a two-deg-of-freedom system equipped with an impact damper was investigated by using this approach and the effects of mode shape, frequency ratio, mass ratio, coefficient of restitution, and damper clearance ratio on the response of the system were determined. This simulation method, which is useful in automated design processes, was used to determine the optimum design parameters of the impact damper.

Application of Electric-Analog Computers to Heat-Transfer and Fluid-Flow Problems

1949 ◽  
Vol 16 (3) ◽  
pp. 247-258
Author(s):  
G. D. McCann ◽  
C. H. Wilts
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
High Speed ◽  
Analog Computer ◽  
Flow Problems ◽  
California Institute Of Technology ◽  
Mathematical Problems ◽  
Electric Analog ◽  
Institute Of Technology ◽  
Moderate Complexity

Abstract There are two general classes of mathematical problems encountered in science and engineering for which high-speed mechanical computation is required. One of these embraces those problems of such complexity that it is impractical to obtain even a few solutions by conventional analysis. In the other class are problems which may be of only moderate complexity, but in which it is necessary to obtain a large number of solutions before the results become of practical value. It is the intent of this paper to discuss some of the applications that have been made of the California Institute of Technology “electric-analog computer” to heat-transfer and fluid-flow problems of both of the classes mentioned.

Vibration of Multifrequency Systems During Acceleration Through Critical Speeds

1949 ◽  
Vol 16 (4) ◽  
pp. 375-382
Author(s):  
G. D. McCann ◽  
R. R. Bennett
Keyword(s):  
Analog Computer ◽  
Degree Of Freedom ◽  
Generalized Solutions ◽  
Critical Speeds ◽  
Constant Magnitude ◽  
Electric Analog ◽  
Two Degree Of Freedom ◽  
Single Constant

Abstract This paper presents generalized solutions for the response of a linear two-degree-of-freedom system excited by a single constant-magnitude sinusoidal force whose frequency varies uniformly with time. These solutions were obtained with the Cal Tech “electric-analog computer” which is described briefly since it has wide application to problems of this type.

Beam-Vibration Analysis With the Electric-Analog Computer

1950 ◽  
Vol 17 (1) ◽  
pp. 13-26
Author(s):  
G. D. McCann ◽  
R. H. MacNeal
Keyword(s):  
Steady State ◽  
Vibration Analysis ◽  
Degrees Of Freedom ◽  
Analog Computer ◽  
Accurate Solution ◽  
Rotary Inertia ◽  
Beam Vibration ◽  
Lumped Constant ◽  
Electric Analog

Abstract The authors have developed a true dynamic analogy which has been used with the Cal Tech electric-analog computer for the rapid and accurate solution of both steady-state and transient beam problems. This analogy has been found well suited to the study of beams having several coupled degrees of freedom, including torsion, simple bending, and bending in a plane. Damping and effects such as rotary inertia may be handled readily. The analogy may also be used in the study of systems involving combined beams and “lumped-constant” elements.

A hybrid computer technique for power spectrum analysis

SIMULATION ◽  
1966 ◽  
Vol 6 (4) ◽  
pp. 258-265
Author(s):  
Lee C. Thomas
Keyword(s):  
Power Spectrum ◽  
Autocorrelation Function ◽  
Analog Computer ◽  
Frequency Multiplier ◽  
Frequency Resolution ◽  
Power Density Spectrum ◽  
Wave Form ◽  
Density Spectrum ◽  
Computer Technique ◽  
State Frequency

A technique is presented by which the power density spectrum of an analog computer waveform may be meas ured to a specified amplitude precision and frequency resolution. The procedure involves sampling the wave form, storing the samples in a digital computer, and dig itally computing the autocorrelation function and the cosine transform of the autocorrelation function to yield the power spectrum. The theory required for selection of the parameters of sampling and computation is presented as are the required methods of data smoothing and proces sing. A description is given of an application of the tech nique to the design of a solid-state frequency multiplier. The computational system is designer-controlled and is capable of giving rapid indications of the effect of changes in the process being simulated on the analog computer.

The Wolfrom Gear Train: A Case of Highest-Complexity Related Modifications of the Tooth Meshing

2009 ◽  
Author(s):  
Kiril Arnaudov ◽  
Dimitar Karaivanov
Keyword(s):  
Design Problem ◽  
High Speed ◽  
Technical Problem ◽  
Gear Train ◽  
Speed Ratio ◽  
Specific Design ◽  
Number Of Teeth

The Wolfrom gear is suitable for high speed ratios with an efficiency which is not optimal, but still acceptable. The version with single-rim satellites has significant design and technological advantages. However, the determination of the most appropriate modification coefficients poses a technical problem as the modifications are now related instead of being chosen independently. The geometrical calculations of the single-rim satellites version are performed in the paper. Speed ratio, number of teeth of the satellites, pressure angles and modification coefficients are determined. Advisable values for these parameters are given. As an example a specific design problem for the replacement of a three-stage planetary reducer (consisting of 15 gears) with a Wolfrom gear train (6 gears) the following calculations were performed.

Using Pontryagin's Maximum Principle to Solve One-Dimensional Optimization Problems, with and without Constraints, on an Iterative Analog Computer

SIMULATION ◽  
1965 ◽  
Vol 4 (6) ◽  
pp. 382-389 ◽  
Author(s):  
Hans L. Steinmetz
Keyword(s):  
Maximum Principle ◽  
Differential Equations ◽  
Time Domain ◽  
Pontryagin’S Maximum Principle ◽  
Analog Computer ◽  
Solution Time ◽  
Pontryagin's Maximum Principle ◽  
Computer Technique ◽  
One Dimensional ◽  
Time Required

An analog computer technique is presented which enables application of Pontryagin's maximum prin ciple to the problem of optimizing control systems. The key problem in using Pontryagin's maximum principle is the extremization of the Hamiltonian function at every instant of time. Since the analog computer is an excellent differential equation solver, it is of advantage to convert this task into a dynamic problem. The technique used to do this is based upon the steepest ascent method. The method is applied to a one-dimensional control problem; higher-di mensional control problems can be treated using the same approach. The argument that an analog computer can solve differential equations with only one independent variable, corresponding to machine time, is true only in a technical sense. In practice it is feasible for cer tain types of problems to integrate one set of differ ential equations sufficiently fast enough so that, while integrating another set of differential equations at a much slower rate, the solution error associated with this approach remains within acceptable limits. When using the analog computer in this way, one time domain always corresponds to the solution time required for solving the differential equations de scribing the system; a second time domain corre sponds to the solution time required for solving an auxiliary set of differential equations which has no direct relationship with the system. Technological improvements and innovations made in the analog computer field during the recent past have contributed to the successful application of this approach.

Microbubble Formation in Collapsing Process of a Single Vapor Bubble Injected in Subcooled Pool

2009 ◽  
Author(s):  
Ichiro Ueno ◽  
Yasusuke Hattori
Keyword(s):  
Heat Flux ◽  
Vapor Bubble ◽  
High Speed ◽  
Narrow Range ◽  
Heated Surface ◽  
Lighting System ◽  
Vapor Bubbles ◽  
Bubble Behavior ◽  
Subcooled Liquid ◽  
Boiling Process

‘Microbubble emission boiling,’ known as MEB, is a phenomenon that emerges in a narrow range of subcooled condition with a higher heat flux than critical heat flux (CHF) accompanying with microbubble emission from the heated surface. The authors focus on the condensing process of vapor bubbles in order to comprehend the mechanism of the microbubble formation and emitting processes. In order to simplify a surely complex boiling process, the authors try to extract an interaction between the vapor bubble and the subcooled bulk in a boiling phenomenon, that is, growing and collapsing processes of a vapor bubble ejected to subcooled liquid bath. Vapor bubble is produced by vapor generate system, and ejected to a bulk of saturated distilled water at a designated degree of subcooling. The degree of subcooling is varied from 0 to 50 K. The growing/collapsing of vapor bubble behavior is detected by employing a high-speed camera at frame rates up to 50,000 fps with a back-lighting system. In the present study, the process of microbubble emission as well as the process of the irrupting vapor bubbles to the subcooled bulk is compared to that in a MEB on a thin wire.

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