Back-Calculation Method of Subgrade Modulus Based on Traffic Speed Deflectometer

CICTP 2020 ◽  
2020 ◽  
Author(s):  
Guoshuai Zang ◽  
Haizhu Lu ◽  
Guanglai Jin ◽  
Zhixiang Zhang
Keyword(s):  
Calculation Method ◽  
Back Calculation ◽  
Subgrade Modulus ◽  
Traffic Speed

Study on Correction Method of Subgrade Modulus Based on FWD

2013 ◽  
Vol 579-580 ◽  
pp. 862-865
Author(s):  
Xiao Hua Luo ◽  
Qing Yang ◽  
Xin Qiu
Keyword(s):  
Resilient Modulus ◽  
Implementation Process ◽  
Correction Method ◽  
Deformation Analysis ◽  
Test Results ◽  
Moisture Condition ◽  
Back Calculation ◽  
The Mean ◽  
Subgrade Modulus ◽  
New Perspective

In order to calibrate subgrade back calculation modulus, the correction method of subgrade back calculation modulus was put forward based on theoretical analysis and indoor/outdoor experiments, and the detailed implementation process was analyzed combined the latest results of subgrade dynamic modulus and subgrade moisture forecast. The results show that the equivalent resilient modulus of subgrade simultaneously consider subgrade material moisture condition and stress dependency and the forecast equation has higher correlation. The ratio of the loading plate test results to the predicted results ranges from 0.25 to 0.4 and the mean is 0.32, which conforms to the requirements of AASHTO normal value. Utilizing the scale factor 0.65 to calibrate subgrade back calculation modulus is viable and validated. The results provides a new perspective and approach for deformation analysis of subgrade structure. As well, the established method makes up the defect that can't reflect the effect of moisture and stress on equivalent resilient modulus of subgrade.

scholarly journals AIDS Incubation Period: A Statistical Review

2006 ◽  
Vol 5 (2) ◽  
pp. 39-56
Author(s):  
Sahana Prasad ◽  
Nagaraja Rao C. ◽  
T. Srivenkataramana
Keyword(s):  
Statistical Analysis ◽  
Incubation Period ◽  
Calculation Method ◽  
Statistical Review ◽  
World Today ◽  
Rapid Spread ◽  
The World ◽  
The Future ◽  
Back Calculation ◽  
Socioeconomic Consequences

One of the major concerns of healthcare in the world today is HIV/AIDS.The health and socioeconomic consequences of a rapid spread of AIDS are very serious.Thus we need accurate forecasts of the future course of the epidemic.The special feature of AIDS is its long incubation period,whose distribution is difficult to estimate partly due to its length and partly due to its nature of the infected cohorts being followed or identified.This article mainly discusses the features of AIDS incubation period and reviews statistical analysis of a few models developed for the estimation of the incubation period.One of the i9mportant methods of projection namely,Back Calculation method is also discussed.

scholarly journals Calibration Method of Accelerometer Based on Rotation Principle Using Double Turntable Centrifuge

Micromachines ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 62
Author(s):  
Xianshan Dong ◽  
Xinlong Huang ◽  
Guizhen Du ◽  
Qinwen Huang ◽  
Yixiong Huang ◽  
...  
Keyword(s):  
Calculation Method ◽  
Calibration Method ◽  
Calibration Procedure ◽  
Scale Factor ◽  
Centripetal Acceleration ◽  
Mems Accelerometer ◽  
Key Technology ◽  
Acceleration Vector ◽  
Back Calculation ◽  
Input Acceleration

For linear accelerometers, calibration with a precision centrifuge is a key technology, and the input acceleration imposed on the accelerometer should be accurately obtained in the calibration. However, there are often errors in the installation of sample that make the calibration inaccurate. To solve installation errors and obtain the input acceleration in the calibration of the accelerometer, a calibration method based on the rotation principle using a double turntable centrifuge is proposed in this work. The key operation is that the sub-turntable is rotated to make the input axis of the accelerometer perpendicular to the direction of the centripetal acceleration vector. Models of installation errors of angle and radius were built. Based on these models, the static radius and input acceleration can be obtained accurately, and the calibration of the scale factor, nonlinearity and asymmetry can be implemented. Using this method, measurements of the MEMS accelerometer with a range of ±30 g were carried out. The results show that the discrepancy of performance obtained from different installation positions was smaller than 100 ppm after calibrating the input acceleration. Moreover, the results using this method were consistent with those using the back-calculation method. These results demonstrate that the effectiveness of our proposed method was confirmed. This method can measure the static radius directly eliminating the installation errors of angle and radius, and it simplifies the accelerometer calibration procedure.

Visco-Elastic Back-Calculation of Traffic Speed Deflectometer Measurements

2019 ◽  
Vol 2673 (12) ◽  
pp. 439-448 ◽  
Author(s):  
Christoffer P. Nielsen
Keyword(s):  
Calculation Procedure ◽  
Falling Weight Deflectometer ◽  
Calculation Algorithm ◽  
Structural Evaluation ◽  
Driving Speed ◽  
Back Calculation ◽  
Traffic Speed ◽  
Falling Weight ◽  
Calculation Procedures ◽  
Project Level

The traffic speed deflectometer (TSD) has proven a valuable tool for network level structural evaluation. At the project level, however, the use of TSD data is still quite limited. An obstacle to the use of TSD at the project level is that the standard approaches to back-calculation of pavement properties are based on the falling weight deflectometer (FWD). The FWD experiment is similar, but not equivalent, to the TSD experiment, and therefore it is not straightforward to apply the traditional FWD back-calculation procedures to TSD data. In this paper, a TSD-specific back-calculation procedure is presented. The procedure is based on a layered linear visco-elastic pavement model and takes the driving speed of the vehicle into account. This is in contrast to most existing back-calculation procedures, which treat the problem as static and the pavement as purely elastic. The developed back-calculation procedure is tested on both simulated and real TSD data. The real TSD measurements exhibit significant effects of damping and visco-elasticity. The back-calculation algorithm is able to capture these effects and yields model fits in excellent agreement with the measured values.

scholarly journals A novel length back-calculation approach accounting for ontogenetic changes in the fish length – otolith size relationship during the early life of sprat (Sprattus sprattus)

2012 ◽  
Vol 69 (7) ◽  
pp. 1214-1229 ◽  
Author(s):  
Claudia C. Günther ◽  
Axel Temming ◽  
Hannes Baumann ◽  
Bastian Huwer ◽  
Christian Möllmann ◽  
...  
Keyword(s):  
Calculation Method ◽  
Juvenile Stage ◽  
Growth Potential ◽  
Fish Length ◽  
Ontogenetic Changes ◽  
Sprattus Sprattus ◽  
Early Juvenile ◽  
Length Growth ◽  
Early Juvenile Stage ◽  
Back Calculation

An individual-based length back-calculation method was developed for juvenile Baltic sprat ( Sprattus sprattus ), accounting for ontogenetic changes in the relationship between fish length and otolith length. In sprat, metamorphosis from larvae to juveniles is characterized by the coincidence of low length growth, strong growth in body height, and maximal otolith growth. Consequently, the method identifies a point of metamorphosis for an individual as the otolith radius at maximum increment widths. By incorporating this information in our back-calculation method, estimated length growth for the early larval stage was more than 60% higher compared with the result of the biological intercept model. After minimal length growth during metamorphosis, we found the highest increase in length during the early juvenile stage. We thus located the strongest growth potential in the early juvenile stage, which is supposed to be critical in determining recruitment strength in Baltic sprat.

A practical approach to falling-weight deflectometer (FWD) data reduction

2005 ◽  
Vol 42 (2) ◽  
pp. 641-645 ◽  
Author(s):  
Dieter Stolle ◽  
Peijun Guo
Keyword(s):  
Mechanical Properties ◽  
Shear Modulus ◽  
Falling Weight Deflectometer ◽  
Layer System ◽  
Surface Loading ◽  
Back Calculation ◽  
Pavement Response ◽  
Subgrade Modulus ◽  
Falling Weight

The authors present a simplified methodology for preprocessing falling-weight deflectometer (FWD) data, which identify a pseudo-static pavement response to surface loading. This allows one to employ static analysis to back-calculate the mechanical properties of the pavement–subgrade system. It is shown that the subgrade modulus can be identified, independent of the details of the pavement structure itself, at least for a two-layer system. The quality of the effective shear modulus is sensitive to the value of Poisson's ratio selected.Key words: pavement–subgrade system, subgrade modulus, back-calculation, FWD.

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