Hysteretic effect considered monitoring model for interpreting abnormal deformation behavior of arch dams: A case study

2019 ◽  
Vol 26 (10) ◽  
Author(s):  
Shaowei Wang ◽  
Yingli Xu ◽  
Chongshi Gu ◽  
Tengfei Bao ◽  
Qun Xia ◽  
...  
Keyword(s):  
Deformation Behavior ◽  
Arch Dams ◽  
Monitoring Model ◽  
Hysteretic Effect

scholarly journals Deformation Behavior of Nanocrystalline Body-Centered Cubic Iron with Segregated, Foreign Interstitial: A Molecular Dynamics Study

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5351
Author(s):  
Ahmed Tamer AlMotasem ◽  
Matthias Posselt ◽  
Tomas Polcar
Keyword(s):  
Molecular Dynamics ◽  
Grain Boundary ◽  
Deformation Behavior ◽  
Large Scale ◽  
Grain Boundary Sliding ◽  
Carbon And Nitrogen ◽  
Embedded Atom ◽  
Boundary Sliding ◽  
Dynamics Simulations

In the present work, modified embedded atom potential and large-scale molecular dynamics’ simulations were used to explore the effect of grain boundary (GB) segregated foreign interstitials on the deformation behavior of nanocrystalline (nc) iron. As a case study, carbon and nitrogen (about 2.5 at.%) were added to (nc) iron. The tensile test results showed that, at the onset of plasticity, grain boundary sliding mediated was dominated, whereas both dislocations and twinning were prevailing deformation mechanisms at high strain. Adding C/N into GBs reduces the free excess volume and consequently increases resistance to GB sliding. In agreement with experiments, the flow stress increased due to the presence of carbon or nitrogen and carbon had the stronger impact. Additionally, the simulation results revealed that GB reduction and suppressing GBs’ dislocation were the primary cause for GB strengthening. Moreover, we also found that the stress required for both intragranular dislocation and twinning nucleation were strongly dependent on the solute type.

A GPS Data Based Monitor Model of Unoccupied Taxis at Transportation Hubs

2014 ◽  
Vol 641-642 ◽  
pp. 767-772
Author(s):  
Xiao Lin Che ◽  
Jian Cheng Weng ◽  
Quan Yu ◽  
Tian Yu Xu
Keyword(s):  
Travel Demand ◽  
Field Investigation ◽  
Gps Data ◽  
Passenger Transport ◽  
Peak Period ◽  
International Airport ◽  
Model Based ◽  
Monitoring Model ◽  
Scientific Analysis

Taxis account for a large percent of urban public passenger transport. This research proposes a monitor model of analyzing unoccupied taxis at a defined area. By scientific analysis of taxi GPS data precision and quality, 16,255 valid taxis in register list were filtered, and two coefficients were introduced to correct the taxi monitoring model. Based on the location reports of valid taxis, the number of unoccupied taxi which was able to dispatch to meet passengers’ demands can be predicted. Take the terminal 3 of Beijing Capital International Airport as a case study, the field investigation results show that the precision of model reached 87.25%. It provides reliable systematic support and alert for a low taxi number when there comes up large taxi travel demand during the peak period or under severe weathers.

scholarly journals A monitoring model for the stress on a super-high arch dam during pre-impoundment construction

2020 ◽  
Vol 20 (8) ◽  
pp. 3604-3614
Author(s):  
Jingtai Niu ◽  
Xiang Luo ◽  
Zhiping Deng ◽  
Yang Zhang ◽  
Yingjia Guo ◽  
...  
Keyword(s):  
Structural Characteristics ◽  
In Situ Stress ◽  
Arch Dam ◽  
Stress Monitoring ◽  
High Arch Dam ◽  
Factors Affecting ◽  
Arch Dams ◽  
Monitoring Model ◽  
Elastoplastic Constitutive Model ◽  
High Arch Dams

Abstract This paper presents a proposed model for monitoring the stress on a super-high arch dam during construction. Using mathematics, mechanics, and dam engineering principles, the mathematical expressions of the self-weight component of the dam prior to and following the sealing of the bottom of the arch were derived. The visco-elastoplastic constitutive model of dam concrete during construction was identified and used to develop a stress monitoring model for a super-high arch dam. Based on in-situ stress monitoring data collected during the construction of a super-high arch dam, the stress monitoring model was applied to a super-high arch dam accounting for future impoundment, and the key components of the monitoring model were isolated. The results show that the model has high fitting accuracy and incorporates an appropriate selection of factors affecting dam stress. The hydrograph of each component conforms to the structural characteristics of super-high arch dams during construction. This model overcomes the limitations of applying the complete self-weight of the dam body on the cantilever beam and was validated using data from a super-high arch dam construction project. Thus, this paper provides evidence for a safety monitoring model for super-high arch dams during construction.

scholarly journals Application of Spatiotemporal Hybrid Model of Deformation in Safety Monitoring of High Arch Dams: A Case Study

2020 ◽  
Vol 17 (1) ◽  
pp. 319 ◽  
Author(s):  
Chongshi Gu ◽  
Xiao Fu ◽  
Chenfei Shao ◽  
Zhongwen Shi ◽  
Huaizhi Su
Keyword(s):  
Hybrid Model ◽  
Data Representation ◽  
Arch Dam ◽  
Deformation Analysis ◽  
Arch Dams ◽  
Dam Operation ◽  
Representation Method ◽  
The Relationship ◽  
Safety And Stability

As an important feature, deformation analysis is of great significance to ensure the safety and stability of arch dam operation. In this paper, Jinping-I arch dam with a height of 305 m, which is the highest dam in the world, is taken as the research object. The deformation data representation method is analyzed, and the processing method of deformation spatiotemporal data is discussed. A deformation hybrid model is established, in which the hydraulic component is calculated by the finite element method, and other components are still calculated by the statistical model method. Since the relationship among the measuring points is not taken into account and the overall situation cannot be fully reflected in the hybrid model, a spatiotemporal hybrid model is proposed. The measured values and coordinates of all the typical points with pendulums of the arch dam are included in one spatiotemporal hybrid model, which is feasible, convenient, and accurate. The model can predict the deformation of any position on the arch dam. This is of great significance for real-time monitoring of deformation and stability of Jinping-I arch dam and ensuring its operation safety.

Numerical study on predicting and correcting assembly deformation of a large fuselage panel during digital assembly

2014 ◽  
Vol 34 (2) ◽  
pp. 204-216 ◽  
Author(s):  
Yunbo Bi ◽  
Weimiao Yan ◽  
Yinglin Ke
Keyword(s):  
Deformation Behavior ◽  
Numerical Study ◽  
Numerical Control ◽  
Fe Model ◽  
Least Squares Regression ◽  
Content Type ◽  
Position Errors ◽  
Assembly Accuracy ◽  
High Level

Purpose – The deformation of a large fuselage panel is unavoidable due to its weak-stiffness and low-rigidity. Sometimes, the assembly accuracy of the panel is out of tolerance. The purpose of this paper is to propose a method to predict and correct the assembly deformation of a large fuselage panel during digital assembly by using a finite element (FE) analysis and partial least squares regression (PLSR) method. Design/methodology/approach – A FE model is proposed to optimize the layout of load-transmitting devices to reduce panel deformation after the process of hoisting and supporting. Furthermore, another FE model is established to investigate the deformation behavior of the panel. By orthogonal simulations, the position error data of measurement points representing the precision of the panel are obtained. Then, a mathematical model of the relationship between the position errors of measurement points on the panel and the displacements of numerical control positioners is developed based on the PLSR method. Findings – The case study shows that the model has a high level of computing accuracy and that the proposed method is an efficient way to correct the panel deformation in digital assembly. Originality/value – The results of this study will enhance the understanding of the deformation behavior of a panel in aircraft digital assembly and help to improve the assembly precision systematically and efficiently.

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