Validation of Various Linear Spring Stiffness Definitions for a Simple Physical Model for Vibrational Analysis of Cracked Beam Elements Subjected to a Combination of Transverse Loads

2009 ◽  
Author(s):  
M. Skrinar ◽  
T. Pliberšek
Keyword(s):  
Physical Model ◽  
Vibrational Analysis ◽  
Spring Stiffness ◽  
Cracked Beam ◽  
Beam Elements ◽  
Transverse Loads ◽  
Simple Physical Model ◽  
Linear Spring

Validation of GOES-Based Insolation Estimates Using Data from the U.S. Climate Reference Network

2005 ◽  
Vol 6 (4) ◽  
pp. 460-475 ◽  
Author(s):  
Jason A. Otkin ◽  
Martha C. Anderson ◽  
John R. Mecikalski ◽  
George R. Diak
Keyword(s):  
Physical Model ◽  
Land Surface ◽  
Radiative Transfer Model ◽  
Reference Network ◽  
Transfer Model ◽  
Model Errors ◽  
Diverse Range ◽  
Simple Physical Model ◽  
Averaged Model ◽  
The U.S

Abstract Reliable procedures that accurately map surface insolation over large domains at high spatial and temporal resolution are a great benefit for making the predictions of potential and actual evapotranspiration that are required by a variety of hydrological and agricultural applications. Here, estimates of hourly and daily integrated insolation at 20-km resolution, based on Geostationary Operational Environmental Satellite (GOES) visible imagery are compared to pyranometer measurements made at 11 sites in the U.S. Climate Reference Network (USCRN) over a continuous 15-month period. Such a comprehensive survey is necessary in order to examine the accuracy of the satellite insolation estimates over a diverse range of seasons and land surface types. The relatively simple physical model of insolation that is tested here yields good results, with seasonally averaged model errors of 62 (19%) and 15 (10%) W m−2 for hourly and daily-averaged insolation, respectively, including both clear- and cloudy-sky conditions. This level of accuracy is comparable, or superior, to results that have been obtained with more complex models of atmospheric radiative transfer. Model performance can be improved in the future by addressing a small elevation-related bias in the physical model, which is likely the result of inaccurate model precipitable water inputs or cloud-height assessments.

Modeling of a Beam and a Rotor with an Edge Crack Using Dissimilar Elements

2003 ◽  
Vol 9 (10) ◽  
pp. 1159-1187 ◽  
Author(s):  
A. Nandi ◽  
S. Neogy
Keyword(s):  
Finite Elements ◽  
Stress Field ◽  
Edge Crack ◽  
Three Dimensional ◽  
Transition Element ◽  
Two Dimensional ◽  
Cracked Beam ◽  
One Dimensional ◽  
Beam Elements ◽  
Dimensional Plane

Vibration-based diagnostic methods are used for the detection of the presence of cracks in beams and other structures. To simulate such a beam with an edge crack, it is necessary to model the beam using finite elements. Cracked beam finite elements, being one-dimensional, cannot model the stress field near the crack tip, which is not one-dimensional. The change in neutral axis is also not modeled properly by cracked beam elements. Modeling of such beams using two-dimensional plane elements is a better approximation. The best alternative would be to use three-dimensional solid finite elements. At a sufficient distance away from the crack, the stress field again becomes more or less one-dimensional. Therefore, two-dimensional plane elements or three-dimensional solid elements can be used near the crack and one-dimensional beam elements can be used away from the crack. This considerably reduces the required computational effort. In the present work, such a coupling of dissimilar elements is proposed and the required transition element is formulated. A guideline is proposed for selecting the proper dimensions of the transition element so that accurate results are obtained. Elastic deformation, natural frequency and dynamic response of beams are computed using dissimilar elements. The finite element analysis of cracked rotating shafts is complicated because of the fact that elastic deformations are superposed on the rigid-body motion (rotation about an axis). A combination of three-dimensional solid elements and beam elements in a rotating reference is proposed here to model such rotors.

Simple physical model of coronary vasodilation

1987 ◽  
Vol 9 (2) ◽  
pp. 148-152 ◽  
Author(s):  
D. Gattullo ◽  
G. Losano ◽  
P. Riffero ◽  
G.P. Soardo ◽  
G. Vacca
Keyword(s):  
Physical Model ◽  
Coronary Vasodilation ◽  
Simple Physical Model

A New Seismic-Isolation Device Applied in Continuous Beam Bridge

2011 ◽  
Vol 194-196 ◽  
pp. 2008-2013
Author(s):  
Bin Yan
Keyword(s):  
Seismic Performance ◽  
Seismic Isolation ◽  
Viscous Damper ◽  
Continuous Beam ◽  
Spring Stiffness ◽  
Continuous Beam Bridge ◽  
Linear Spring ◽  
Meizoseismal Area ◽  
Isolation Device ◽  
Beam Bridge

Continuous beam bridge was widely used, while seismic problem of it was prominent in meizoseismal area. According to seismic-isolation principle and mechanism of PSD, seismic performance of PSD were studied and the parameters of PSD were analyzed later, based on south approach of North Branch of Xia-Zhang Sea-Crossing Bridge. It was found that PSD, a combination of preloaded spring and liquid viscous damper, was an effective seismic-isolation device which could significantly reduce the seismic response of continuous beam bridge in longitudinal and transverse direction. Damper coefficient was the main parameter of PSD, while preloaded force, linear spring stiffness and damper index had a little effect on seismic performance of PSD.

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