scholarly journals Theoretical Studies on the Longitudinal Inhomogeneity of Track Stiffness and a Track Status Estimation Method

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Wen Bai ◽  
Lei Xu
Keyword(s):  
State Estimation ◽  
Estimation Method ◽  
Coupled Model ◽  
The Finite Element Method ◽  
Random Parameters ◽  
Numerical Studies ◽  
Longitudinal Inhomogeneity ◽  
Environmental Variations ◽  
Track Stiffness ◽  
Track Status

Due to material multiplicity, rigid-flexible hybrid and environmental variations, and so forth, the properties of the tracks will be inevitably changed due to the cyclic loads temporally and spatially. In this paper, a theoretical study is conducted to clarify the influence of the longitudinal inhomogeneity of track stiffness on system responses and then a general state estimation method is proposed to inversely predict the parametric distribution of the tracks. To achieve these purposes, a 3D nonlinear vehicle-track coupled model is firstly constructed, where track systems are established by the finite element method with random parameters. Based on this dynamic model, the distribution characteristics of system responses due to random parametric excitations are properly revealed. The numerical studies show that the longitudinal inhomogeneity of track supporting stiffness has significant effects on system responses; besides, the response distributions are varied against different parametric distributions. Finally, a representative example is demonstrated to show the effectiveness of the proposed track state estimation method.

scholarly journals A Two-layer Sequential State Estimation Method for electricity and heat Networks

2021 ◽  
Vol 1802 (3) ◽  
pp. 032088
Author(s):  
Xiaonan Yang ◽  
Yansheng Lang ◽  
Heng Zhang ◽  
Yan Lv ◽  
Chengzhi Zhu ◽  
...  
Keyword(s):  
State Estimation ◽  
Estimation Method ◽  
Heat Networks

scholarly journals Investigations on Torsion of the Two-Chords Single Laced Members

2017 ◽  
Vol 25 (2) ◽  
pp. 147-160
Author(s):  
Paweł Lorkowski ◽  
Bronisław Gosowski
Keyword(s):  
Cross Sections ◽  
Experimental Studies ◽  
The Finite Element Method ◽  
Second Moment ◽  
Steel Columns ◽  
Numerical Studies ◽  
Traction Network ◽  
Railway Traction ◽  
Parametric Analyses ◽  
The Relationship

Abstract The paper presents experimental and numerical studies to determine the equivalent second moment of area of the uniform torsion of the two-chord steel single laced members. The members are used as poles of railway traction network gates, and steel columns of framed buildings as well. The stiffness of uniform torsion of this kind of columns allows to the determine the critical loads of the spatial stability. The experimental studies have been realized on a single - span members with rotation arrested at their ends, loaded by a torque applied at the mid-span. The relationship between angle of rotation of the considered cross-section and the torque has been determined. Appropriate numerical model was created in the ABAQUS program, based on the finite element method. A very good compatibility has been observed between experimental and numerical studies. The equivalent second moment of area of the uniform torsion for analysed members has been determined by comparing the experimental and analytical results to those obtained from differential equation of non-uniform torsion, based on Vlasov’s theory. Additionally, the parametric analyses of similar members subjected to the uniform torsion, for the richer range of cross-sections have been carried out by the means of SOFiSTiK program. The purpose of the latter was determining parametrical formulas for calculation of the second moment of area of uniform torsion.

scholarly journals Assessing ENSO Simulations and Predictions Using Adjoint Ocean State Estimation

2004 ◽  
Vol 17 (22) ◽  
pp. 4301-4315 ◽  
Author(s):  
Dietmar Dommenget ◽  
Detlef Stammer
Keyword(s):  
State Estimation ◽  
Positive Impact ◽  
Coupled Model ◽  
Estimation Procedure ◽  
Time Interval ◽  
Seasonal Forecasts ◽  
Predictive Skill ◽  
Sst Anomaly ◽  
Ocean State Estimation

Abstract Simulations and seasonal forecasts of tropical Pacific SST and subsurface fields that are based on the global Consortium for Estimating the Circulation and Climate of the Ocean (ECCO) ocean-state estimation procedure are investigated. As compared to similar results from a traditional ENSO simulation and forecast procedure, the hindcast of the constrained ocean state is significantly closer to observed surface and subsurface conditions. The skill of the 12-month lead SST forecast in the equatorial Pacific is comparable in both approaches. The optimization appears to have better skill in the SST anomaly correlations, suggesting that the initial ocean conditions and forcing corrections calculated by the ocean-state estimation do have a positive impact on the predictive skill. However, the optimized forecast skill is currently limited by the low quality of the statistical atmosphere. Progress is expected from optimizing a coupled model over a longer time interval with the coupling statistics being part of the control vector.

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