scholarly journals Qualitative Prediction Model for Dynamic Behavior of Ballasted Tracks

2020 ◽  
Vol 10 (18) ◽  
pp. 6258
Author(s):  
Jung-Youl Choi ◽  
Sun-Hee Kim
Keyword(s):  
Dynamic Response ◽  
Prediction Model ◽  
Dynamic Behavior ◽  
Field Measurement ◽  
Field Measurements ◽  
Bending Stress ◽  
Qualitative Prediction ◽  
Proposed Model ◽  
Ballasted Track ◽  
Two Degree Of Freedom

Theoretical, experimental, analytical, and statistical evaluations were performed to predict and assess the dynamic behavior of a ballasted track, such as the track support stiffness, track impact factor, or dynamic wheel–rail forces. Field measurements were then performed to evaluate the dynamic behavior of the ballasted track and its components. A qualitative prediction model was then developed to predict and assess track performance as a function of dynamic wheel-rail force and variation in track support stiffness. The developed two-degree-of-freedom dynamic track model can define the rail pad and ballast stiffness ranges based on designed and measured values. Using the proposed model, qualitative analysis results are presented as a discrete space of various track responses and parameters, rather than as single values. The proposed model was then validated using field measurements, which demonstrated that the proposed model predicted the vertical rail displacement and rail bending stress within approximately 2–5% of the obtained field measurements. Overall, the developed qualitative prediction model allows the dynamic response of in-service ballasted tracks to be estimated as a function of the rail pad and ballast stiffness using only a simple field measurement.

Field study using additional rails and an approach slab as a transition zone from slab track to the ballasted track

2017 ◽  
Vol 232 (4) ◽  
pp. 970-978 ◽  
Author(s):  
H Heydari-Noghabi ◽  
JA Zakeri ◽  
M Esmaeili ◽  
JN Varandas
Keyword(s):  
Transition Zone ◽  
Dynamic Behavior ◽  
Field Tests ◽  
Field Measurements ◽  
Sudden Increase ◽  
Transition Zones ◽  
Slab Track ◽  
Railway Line ◽  
Approach Slab ◽  
Ballasted Track

An abrupt change in the stiffness of railway tracks at the junction between slab track and ballasted track causes increased dynamic loads, asymmetric settlements, damage of track components, and, consequently, increased maintenance costs. Due to this, a transition zone is usually built at the junction between the ballasted and the ballastless tracks to reduce the aforementioned problems. One of the methods suggested as a transition zone in these areas is to use a combination of an approach slab and additional rails. This study evaluates the dynamic behavior of this type of transition zone using field tests and also compares its performance with a transition zone built only with an approach slab. Hence, in the Tehran–Karaj railway line, two types of transition zones were constructed: one including only the approach slab and the other one including additional rails and an approach slab. Then, by conducting some field tests, the dynamic behavior of the track in these two types of transition zones was examined. The results of the field measurements show that for the analyzed case study, at the combined transition zone with additional rails and an approach slab, instead of a sudden increase in rail displacements from the slab track to the ballasted track (i.e. by 53%), initially, in the first part of the transition zone (with additional rails and an approach slab), the deflections increase by an average of 31%, and then in the second part of the transition zone (with additional rails only) the deflections increase additionally by 11%.

Atomic 2D electric field imaging of a Yagi–Uda antenna near-field using a portable Rydberg-atom probe and measurement instrument

2020 ◽  
Vol 9 (5) ◽  
pp. 305-312
Author(s):  
Ryan Cardman ◽  
Luís F. Gonçalves ◽  
Rachel E. Sapiro ◽  
Georg Raithel ◽  
David A. Anderson
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Field Measurement ◽  
Near Field ◽  
Measurement Instrument ◽  
Rydberg Atom ◽  
Field Measurements ◽  
Atom Probe ◽  
Electric Field Measurement ◽  
Measurement Uncertainties

AbstractWe present electric field measurements and imaging of a Yagi–Uda antenna near-field using a Rydberg atom–based radio frequency electric field measurement instrument. The instrument uses electromagnetically induced transparency with Rydberg states of cesium atoms in a room-temperature vapor and off-resonant RF-field–induced Rydberg-level shifts for optical SI-traceable measurements of RF electric fields over a wide amplitude and frequency range. The electric field along the antenna boresight is measured using the atomic probe at a spatial resolution of ${\lambda }_{RF}/2$ with electric field measurement uncertainties below 5.5%, an improvement to RF measurement uncertainties provided by existing antenna standards.

Influence of the backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set

2016 ◽  
Vol 231 (11) ◽  
pp. 2025-2041 ◽  
Author(s):  
Shijing Wu ◽  
Haibo Zhang ◽  
Xiaosun Wang ◽  
Zeming Peng ◽  
Kangkang Yang ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Planetary Gear ◽  
Tooth Wear ◽  
Transmission Error ◽  
Gear Transmission ◽  
Tooth Surface ◽  
Contact Ratio ◽  
The Impact

Backlash is a key internal excitation on the dynamic response of planetary gear transmission. After the gear transmission running for a long time under load torque, due to tooth wear accumulation, the backlash between the tooth surface of two mating gears increases, which results in a larger and irregular backlash. However, the increasing backlash generated by tooth accumulated wear is generally neglected in lots of dynamics analysis for epicyclic gear trains. In order to investigate the impact of backlash generated by tooth accumulated wear on dynamic behavior of compound planetary gear set, in this work, first a static tooth surface wear prediction model is incorporated with a dynamic iteration methodology to get the increasing backlash generated by tooth accumulated wear for one pair of mating teeth under the condition that contact ratio equals to one. Then in order to introduce the tooth accumulated wear into dynamic model of compound planetary gear set, the backlash excitation generated by tooth accumulated wear for each meshing pair in compound planetary gear set is given under the condition that contact ratio equals to one and does not equal to one. Last, in order to investigate the impact of the increasing backlash generated by tooth accumulated wear on dynamic response of compound planetary gear set, a nonlinear lumped-parameter dynamic model of compound planetary gear set is employed to describe the dynamic relationships of gear transmission under the internal excitations generated by worn profile, meshing stiffness, transmission error, and backlash. The results indicate that the introduction of the increasing backlash generated by tooth accumulated wear makes a significant influence on the bifurcation and chaotic characteristics, dynamic response in time domain, and load sharing behavior of compound planetary gear set.

Dynamics of a Two-DOF Parallel Pointing Mechanism

2005 ◽  
Author(s):  
Alessandro Cammarata ◽  
Rosario Sinatra
Keyword(s):  
Numerical Simulation ◽  
Parallel Mechanism ◽  
Inverse Dynamics ◽  
Kinematic Model ◽  
Degree Of Freedom ◽  
Numerical Examples ◽  
Proposed Model ◽  
Dynamic Analyses ◽  
Moving Platform ◽  
Two Degree Of Freedom

This paper presents kinematic and dynamic analyses of a two-degree-of-freedom pointing parallel mechanism. The mechanism consists of a moving platform, connected to a fixed platform by two legs of type PUS (prismatic-universal-spherical). At first a simplified kinematic model of the pointing mechanism is introduced. Based on this proposed model, the dynamics equations of the system using the Natural Orthogonal Complement method are developed. Numerical examples of the inverse dynamics results are presented by numerical simulation.

Field Measurements on Micro-Climate and Cooling Effect of River Wind on Blocks near the River in Wuhan

2011 ◽  
Vol 361-363 ◽  
pp. 1197-1203
Author(s):  
Yan Yan Huang ◽  
Hong Chen ◽  
Ying Cai ◽  
Li Yuan
Keyword(s):  
Urban Planning ◽  
Field Measurement ◽  
Yangtze River ◽  
Field Measurements ◽  
Cooling Effect ◽  
Architecture Design ◽  
Climate Effects ◽  
Adjustment Mechanism

The special climate effects of waterbody have greater influence on the micro-climate of waterfront. Therefore, taking a typical block alongside Yangtze River as example, the researchers make the field measurement of micro-climate at fixed locations and analyze cooling effect of river wind. It aims to find out the micro-climate adjustment mechanism of Yangtze River, thus providing a guidance for urban planning and architecture design.

DYNAMIC BEHAVIOR OF TELESCOPIC CRANES BOOM

2013 ◽  
Vol 13 (01) ◽  
pp. 1350010 ◽  
Author(s):  
IOANNIS G. RAFTOYIANNIS ◽  
GEORGE T. MICHALTSOS
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Dynamic Behavior ◽  
Analytical Model ◽  
Constant Velocity ◽  
Steel Beam ◽  
Continuum Approach ◽  
Theoretical Formulation ◽  
Modal Superposition ◽  
Superposition Technique

Telescopic cranes are usually steel beam systems carrying a load at the tip while comprising at least one constant and one moving part. In this work, an analytical model suitable for the dynamic analysis of telescopic cranes boom is presented. The system considered herein is composed — without losing generality — of two beams. The first one is a jut-out beam on which a variable in time force is moving with constant velocity and the second one is a cantilever with length varying in time that is subjected to its self-weight and a force at the tip also changing with time. As a result, the eigenfrequencies and modal shapes of the second beam are also varying in time. The theoretical formulation is based on a continuum approach employing the modal superposition technique. Various cases of telescopic cranes boom are studied and the analytical results obtained in this work are tabulated in the form of dynamic response diagrams.

scholarly journals Evaluation of a highly refined prediction model in knowledge-based volumetric modulated arc therapy planning for cervical cancer

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Mingli Wang ◽  
Huikuan Gu ◽  
Jiang Hu ◽  
Jian Liang ◽  
Sisi Xu ◽  
...  
Keyword(s):  
Cervical Cancer ◽  
Prediction Model ◽  
Volumetric Modulated Arc Therapy ◽  
Model Evolution ◽  
Prediction Ability ◽  
Knowledge Based ◽  
Proposed Model ◽  
Arc Therapy ◽  
Knowledge Based Planning

Abstract Background and purpose To explore whether a highly refined dose volume histograms (DVH) prediction model can improve the accuracy and reliability of knowledge-based volumetric modulated arc therapy (VMAT) planning for cervical cancer. Methods and materials The proposed model underwent repeated refining through progressive training until the training samples increased from initial 25 prior plans up to 100 cases. The estimated DVHs derived from the prediction models of different runs of training were compared in 35 new cervical cancer patients to analyze the effect of such an interactive plan and model evolution method. The reliability and efficiency of knowledge-based planning (KBP) using this highly refined model in improving the consistency and quality of the VMAT plans were also evaluated. Results The prediction ability was reinforced with the increased number of refinements in terms of normal tissue sparing. With enhanced prediction accuracy, more than 60% of automatic plan-6 (AP-6) plans (22/35) can be directly approved for clinical treatment without any manual revision. The plan quality scores for clinically approved plans (CPs) and manual plans (MPs) were on average 89.02 ± 4.83 and 86.48 ± 3.92 (p < 0.001). Knowledge-based planning significantly reduced the Dmean and V18 Gy for kidney (L/R), the Dmean, V30 Gy, and V40 Gy for bladder, rectum, and femoral head (L/R). Conclusion The proposed model evolution method provides a practical way for the KBP to enhance its prediction ability with minimal human intervene. This highly refined prediction model can better guide KBP in improving the consistency and quality of the VMAT plans.

Dynamic Behavior of Aircraft Wings Modeled as Doubly-Tapered Composite Thin-Walled Beams

1999 ◽  
Author(s):  
Sungsoo Na ◽  
Liviu Librescu
Keyword(s):  
Composite Materials ◽  
Free Vibration ◽  
Dynamic Response ◽  
Dynamic Behavior ◽  
Transverse Shear ◽  
Dynamical Behavior ◽  
Time Dependent ◽  
Aircraft Wings ◽  
Helicopter Blades ◽  
Thin Walled

Abstract A study of the dynamical behavior of aircraft wings modeled as doubly-tapered thin-walled beams, made from advanced anisotropic composite materials, and incorporating a number of non-classical effects such as transverse shear, and warping inhibition is presented. The supplied numerical results illustrate the effects played by the taper ratio, anisotropy of constituent materials, transverse shear flexibility, and warping inhibition on free vibration and dynamic response to time-dependent external excitations. Although considered for aircraft wings, this analysis and results can be also applied to a large number of structures such as helicopter blades, robotic manipulator arms, space booms, tall cantilever chimneys, etc.

Outburst prediction and influencing factors analysis based on Boruta-Apriori and BO-SVM algorithms

2021 ◽  
pp. 1-18
Author(s):  
Zhang Zixian ◽  
Liu Xuning ◽  
Li Zhixiang ◽  
Hu Hongqiang
Keyword(s):  
Feature Selection ◽  
Prediction Model ◽  
Influencing Factors ◽  
Association Rules ◽  
Coal And Gas Outburst ◽  
Feature Subset ◽  
Gas Outburst ◽  
Proposed Model ◽  
Optimal Feature Subset ◽  
Feature Dimension

The influencing factors of coal and gas outburst are complex, now the accuracy and efficiency of outburst prediction and are not high, in order to obtain the effective features from influencing factors and realize the accurate and fast dynamic prediction of coal and gas outburst, this article proposes an outburst prediction model based on the coupling of feature selection and intelligent optimization classifier. Firstly, in view of the redundancy and irrelevance of the influencing factors of coal and gas outburst, we use Boruta feature selection method obtain the optimal feature subset from influencing factors of coal and gas outburst. Secondly, based on Apriori association rules mining method, the internal association relationship between coal and gas outburst influencing factors is mined, and the strong association rules existing in the influencing factors and samples that affect the classification of coal and gas outburst are extracted. Finally, svm is used to classify coal and gas outbursts based on the above obtained optimal feature subset and sample data, and Bayesian optimization algorithm is used to optimize the kernel parameters of svm, and the coal and gas outburst pattern recognition prediction model is established, which is compared with the existing coal and gas outbursts prediction model in literatures. Compared with the method of feature selection and association rules mining alone, the proposed model achieves the highest prediction accuracy of 93% when the feature dimension is 3, which is higher than that of Apriori association rules and Boruta feature selection, and the classification accuracy is significantly improved, However, the feature dimension decreased significantly; The results show that the proposed model is better than other prediction models, which further verifies the accuracy and applicability of the coupling prediction model, and has high stability and robustness.

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