A 2-D Sensitivity Study of the Dynamic Behavior of a Volcanic Hill in the Azores Islands: Comparison with 1-D and 3-D Models

2001 ◽  
Vol 158 (12) ◽  
pp. 2431-2450 ◽  
Author(s):  
M. V. Sincraian ◽  
C. S. Oliveira
Keyword(s):  
Dynamic Behavior ◽  
Sensitivity Study ◽  
Azores Islands

Effects of the Load Distribution Patterns on the Longitudinal Freight Train Dynamics

2007 ◽  
Author(s):  
Masoud Ansari ◽  
Davood Younesian ◽  
Ebrahim Esmailzadeh
Keyword(s):  
Dynamic Behavior ◽  
Load Distribution ◽  
Distribution Patterns ◽  
Sensitivity Study ◽  
Domain Model ◽  
Computer Simulation Model ◽  
Freight Train ◽  
Longitudinal Dynamic ◽  
Loading Patterns ◽  
Train Dynamics

A comprehensive parametric study is carried out on the longitudinal dynamics of a freight train having different loading patterns. A nonlinear time domain model, with one locomotive and nine wagons, is considered. In another simulation the train model has two locomotives and eight wagons, and in both models, every two cars are connected to each other through an automatic coupler. The effects of different load distribution patterns on the coupler forces for the cases of ascending, descending, constant, ascending-descending and descending-ascending are investigated through a parametric sensitivity study. In order to investigate how an empty wagon and its position in a train-consist model may affect the overall longitudinal dynamic behavior of freight trains a second computer simulation model has been developed. Moreover, the best possible position for the second locomotive with the objective of reaching to the lower longitudinal forces, in the case that an additional locomotive is included will be discussed. Finally, an investigation is carried out to determine the kind of couplers with their relevant specifications that must be installed in different positions of a train-consist in order to improve the longitudinal train dynamic behavior.

Modeling and Parameter Identification of Harmonic Drive Systems

1998 ◽  
Vol 120 (4) ◽  
pp. 439-444 ◽  
Author(s):  
H. D. Taghirad ◽  
P. R. Be´langer
Keyword(s):  
Dynamic Behavior ◽  
Model Performance ◽  
Sensitivity Study ◽  
Model Parameters ◽  
Harmonic Drive ◽  
Nonlinear Regression Models ◽  
Proposed Model ◽  
Stiffness Model ◽  
Drive Systems ◽  
Compact Geometry

The unique performance features of harmonic drives, such as high gear ratios and high torque capacities in a compact geometry, justify their widespread industrial application. However, harmonic drive can exhibit surprisingly more complex dynamic behavior than conventional gear transmission. In this paper a systematic way to capture and rationalize the dynamic behavior of the harmonic drive systems is developed. Simple and accurate models for compliance, hysteresis, and friction are proposed, and the model parameters are estimated using least-squares approximation for linear and nonlinear regression models. A statistical measure of variation is defined, by which the reliability of the estimated parameter for different operating condition, as well as the accuracy and integrity of the proposed model is quantified. By these means, it is shown that a linear stiffness model best captures the behavior of the system when combined with a good model for hysteresis. Moreover, the frictional losses of harmonic drive are modeled at both low and high velocities. The model performance is assessed by comparing simulations with the experimental results on two different harmonic drives. Finally, the significance of individual components of the nonlinear model is assessed by a parameter sensitivity study using simulations.

Race Difference in Auditory Sensitivity

1964 ◽  
Vol 7 (4) ◽  
pp. 389-393 ◽  
Author(s):  
David C. Shepherd ◽  
Robert Goldstein ◽  
Benjamin Rosenblüt
Keyword(s):  
White Women ◽  
White Men ◽  
Sensitivity Study ◽  
Auditory Sensitivity ◽  
Race Difference ◽  
Men And Women ◽  
Auditory Thresholds ◽  
Békésy Audiometry ◽  
Method Of Adjustment ◽  
Better Than

Two separate studies investigated race and sex differences in normal auditory sensitivity. Study I measured thresholds at 500, 1000, and 2000 cps of 23 white men, 26 white women, 21 negro men, and 24 negro women using the method of limits. In Study II thresholds of 10 white men, 10 white women, 10 negro men, and 10 negro women were measured at 1000 cps using four different stimulus conditions and the method of adjustment by means of Bekesy audiometry. Results indicated that the white men and women in Study I heard significantly better than their negro counterparts at 1000 and 2000 cps. There were no significant differences between the average thresholds measured at 1000 cps of the white and negro men in Study II. White women produced better auditory thresholds with three stimulus conditions and significantly more sensitive thresholds with the slow pulsed stimulus than did the negro women in Study II.

Ball bearing turbocharger vibration management: application on high speed balancer

2020 ◽  
Vol 21 (6) ◽  
pp. 619
Author(s):  
Kostandin Gjika ◽  
Antoine Costeux ◽  
Gerry LaRue ◽  
John Wilson
Keyword(s):  
Dynamic Behavior ◽  
High Speed ◽  
Internal Combustion Engines ◽  
Ball Bearing ◽  
Squeeze Film ◽  
Design And Technology ◽  
Squeeze Film Damper ◽  
Damping Coefficients ◽  
Bearing Loads ◽  
Stiffness And Damping

Today's modern internal combustion engines are increasingly focused on downsizing, high fuel efficiency and low emissions, which requires appropriate design and technology of turbocharger bearing systems. Automotive turbochargers operate faster and with strong engine excitation; vibration management is becoming a challenge and manufacturers are increasingly focusing on the design of low vibration and high-performance balancing technology. This paper discusses the synchronous vibration management of the ball bearing cartridge turbocharger on high-speed balancer and it is a continuation of papers [1–3]. In a first step, the synchronous rotordynamics behavior is identified. A prediction code is developed to calculate the static and dynamic performance of “ball bearing cartridge-squeeze film damper”. The dynamic behavior of balls is modeled by a spring with stiffness calculated from Tedric Harris formulas and the damping is considered null. The squeeze film damper model is derived from the Osborne Reynolds equation for incompressible and synchronous fluid loading; the stiffness and damping coefficients are calculated assuming that the bearing is infinitely short, and the oil film pressure is modeled as a cavitated π film model. The stiffness and damping coefficients are integrated on a rotordynamics code and the bearing loads are calculated by converging with the bearing eccentricity ratio. In a second step, a finite element structural dynamics model is built for the system “turbocharger housing-high speed balancer fixture” and validated by experimental frequency response functions. In the last step, the rotating dynamic bearing loads on the squeeze film damper are coupled with transfer functions and the vibration on the housings is predicted. The vibration response under single and multi-plane unbalances correlates very well with test data from turbocharger unbalance masters. The prediction model allows a thorough understanding of ball bearing turbocharger vibration on a high speed balancer, thus optimizing the dynamic behavior of the “turbocharger-high speed balancer” structural system for better rotordynamics performance identification and selection of the appropriate balancing process at the development stage of the turbocharger.

A Sensitivity Study on Low Salinity Waterflooding

2017 ◽  
Vol 04 (03) ◽  
pp. 231-236 ◽  
Author(s):  
Barham S. Mahmood ◽  
Jagar Ali ◽  
Shirzad B. Nazhat ◽  
David Devlin
Keyword(s):  
Sensitivity Study ◽  
Low Salinity ◽  
Low Salinity Waterflooding
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