scholarly journals Study on the Comfort of Pedestrians on Landscape Footpath Paved on the Suspension Monorail System

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Zhou Li ◽  
Yuancheng Wei ◽  
Xiaolong Zheng ◽  
Yongping Zeng ◽  
Xinyu Xu ◽  
...  
Keyword(s):  
Vertical Displacement ◽  
Dynamic Responses ◽  
Lateral Acceleration ◽  
Vertical Acceleration ◽  
Analysis Model ◽  
Eccentric Load ◽  
Lateral Response ◽  
First Time ◽  
Peak Value ◽  
Track Beam

This is the first time that the landscape footpath is realized on the suspension monorail system. To study the comfort of pedestrians on the landscape footpath when the vehicle passes, the dynamic responses of the track beam and the landscape footpath at different speeds were analyzed using the established vehicle-bridge dynamic analysis model. To evaluate the comfort of pedestrians on the landscape footpath, two indexes, Root Mean Square (RMS) value of acceleration (ISO 10137) and peak value of acceleration (EN 03), were adopted. Results show that the displacement and acceleration responses of landscape footpath and track beam are obviously different. Vertical displacement of the track beam is much larger than that of the landscape footpath due to the eccentric load of vehicles. Due to the displacement and rotation of the structural components which support the landscape footpath, the lateral response transferred to the landscape footpath would be slightly weakened. Maximum RMS values of the lateral and vertical acceleration of landscape footpath are 0.162 m/s2 and 0.169 m/s2, respectively, which meet the requirements of ISO 10137. Peak lateral acceleration is 0.546 m/s2, which reaches CL3 standard, and the peak vertical acceleration is 0.548 m/s2, which reaches CL2 standard. Lateral comfort is slightly worse than vertical comfort.

scholarly journals Running Safety of Trains under Vessel-Bridge Collision

2015 ◽  
Vol 2015 ◽  
pp. 1-11
Author(s):  
Yongle Li ◽  
Jiangtao Deng ◽  
Bin Wang ◽  
Chuanjin Yu
Keyword(s):  
Element Model ◽  
Dynamic Responses ◽  
Lateral Acceleration ◽  
Vertical Acceleration ◽  
Running Safety ◽  
Derailment Coefficient ◽  
Parametric Studies ◽  
Train Speed ◽  
Unloading Rate ◽  
Bridge System

To optimize the sensor placement of the health monitoring system, the dynamic behavior of the train-bridge system subjected to vessel-collision should be studied in detail firstly. This study thus focuses on the characteristics of a train-bridge system under vessel-bridge collision. The process of the vessel-bridge collision is simulated numerically with a reliable finite element model (FEM). The dynamic responses of a single car and a train crossing a cable-stayed bridge are calculated. It is shown that the collision causes significant increase of the train’s lateral acceleration, lateral wheelset force, wheel unloading rate, and derailment coefficient. The effect of the collision on the train’s vertical acceleration is much smaller. In addition, parametric studies with various train’s positions, ship tonnage, and train speed are performed. If the train is closer to the vessel-bridge collision position or the ship tonnage is larger, the train will be more dangerous. There is a relatively high probability of running danger at a low speed, resulting from longer stay of the train on the bridge. The train’s position, the ship tonnage, and the train speed must be considered when determining the most adverse conditions for the trains running on bridges under vessel-bridge collision.

Quality of life in adolescents and young adults with CHD is not reduced: a systematic review and meta-analysis

2015 ◽  
Vol 26 (3) ◽  
pp. 415-425 ◽  
Author(s):  
Morten Schrøder ◽  
Kirsten A. Boisen ◽  
Jesper Reimers ◽  
Grete Teilmann ◽  
Jesper Brok
Keyword(s):  
Quality Of Life ◽  
Systematic Review ◽  
Young Adults ◽  
Meta Analysis ◽  
Adolescents And Young Adults ◽  
Analysis Model ◽  
Significant Difference ◽  
Newcastle Ottawa Scale ◽  
First Time

AbstractPurposeWe performed a systematic review and meta-analysis of observational studies assessing quality of life in adolescents and young adults born with CHD compared with age-matched controls.MethodsWe carried out a systematic search of the literature published in Medline, Embase, PsychINFO, and the Cochrane Library’s Database (1990–2013); two authors independently extracted data from the included studies. We used the Newcastle–Ottawa scale for quality assessment of studies. A random effects meta-analysis model was used. Heterogeneity was assessed using the I2-test.ResultsWe included 18 studies with 1786 patients. The studies were of acceptable-to-good quality. The meta-analysis of six studies on quality of life showed no significant difference – mean difference: −1.31; 95% confidence intervals: −6.51 to +3.89, I2=90.9% – between adolescents and young adults with CHD and controls. Similar results were found in 10 studies not eligible for the meta-analysis. In subdomains, it seems that patients had reduced physical quality of life; however, social functioning was comparable or better compared with controls.ConclusionFor the first time in a meta-analysis, we have shown that quality of life in adolescents and young adults with CHD is not reduced when compared with age-matched controls.

Dynamic Characteristic Analysis of Irregularity under Turnout by Vehicle-Turnout Rigid-Flexible Coupling Model

2014 ◽  
Vol 945-949 ◽  
pp. 591-595 ◽  
Author(s):  
Meng Chen ◽  
Yan Yun Luo ◽  
Bin Zhang
Keyword(s):  
Finite Element ◽  
Longitudinal Direction ◽  
Element Model ◽  
Vertical Displacement ◽  
Coupling Model ◽  
Interaction Force ◽  
Vertical Acceleration ◽  
Characteristic Analysis ◽  
Flexible Coupling ◽  
Multi Body

Finite element model of track in frog zone is built by vehicle-turnout system dynamics. Considering variation of rail section and elastic support, bending deformation of turnout sleeper, spacer block and sharing pad effects, the track integral rigidity distribution in longitudinal direction is calculated in the model. Vehicle-turnout rigid-flexible coupling model is built by finite element method (FEM), multi-body system (MBS) dynamics and Hertz contact theory. With the regularity solution that different stiffness is applied for rubber pad under sharing pad of different turnout sleeper zone, analysis the variation of vertical acceleration of bogie and wheelset, rail vertical displacement and wheel-rail interaction force, this paper proves that setting reasonable rubber pad stiffness is an efficient method to solve rigidity irregularity problem.

Detailed Stress Analysis of a Spherical Acrylic Submersible by 3-D Finite Element Modeling

1999 ◽  
Author(s):  
Partha S. Das
Keyword(s):  
Finite Element ◽  
Numerical Modeling ◽  
Dissimilar Materials ◽  
Analysis Model ◽  
Element Analysis ◽  
Finite Element Analysis Model ◽  
New Model ◽  
Ocean Exploration ◽  
Near Future ◽  
First Time

Abstract Harbor Branch Oceanographic Institution (HBOI) designed, built and has operated two JOHNSON-SEA-LINK (JSL) manned submersibles for the past 25 years. The JSL submersibles each incorporate a 66–68 in. (1.6764–1.7272 m) OD, 4–5.25 in. (0.1016–0.13335 m) thick acrylic two-man sphere as a Pressure Vessel for Human Occupancy (PVHO). This type of spherical acrylic sphere or submersible was first introduced in around 1970 and is known as Naval Experimental Manned Observatory (NEMO) submersibles. As the demand increases for ocean exploration to 3000 ft. (914.4 m) depth to collect samples, to study the ocean surfaces, the problem of developing cracks at the interface of these manned acrylic submersibles following few hundred dives have become a common phenomena. This has drawn considerable attentions for reinvestigation of the spherical acrylic submersible in order to overcome this crack generation problem at the interface. Therefore, a new full-scale 3-D nonlinear FEA (Finite Element Analysis) model, similar to the spherical acrylic submersible that HBOI uses for ocean exploration, has been developed for the first time in order to simulate the structural behavior at the interface and throughout the sphere, for better understanding of the mechanical behavior. Variation of the stiffness between dissimilar materials at the interface, lower nylon gasket thickness, over designed aluminum hatch are seemed to be few of the causes for higher stresses within acrylic sphere at the nylon gasket/acrylic interface. Following the basic understanding of the stresses and relative displacements at the interface and within different parts of the submersible, various models have been developed on the basis of different shapes and thickness of nylon gaskets, openings of the acrylic sphere, hatch geometry and its materials, specifically to study their effect on the overall performance of the acrylic submersible. Finally, the new model for acrylic submersible has been developed by redesigning the top aluminum hatch and hatch ring, the sphere openings at both top and bottom, as well as the nylon gasket inserts. Altogether this new design indicates a significant improvement over the existing spherical acrylic submersible by reducing the stresses at the top gasket/acrylic interface considerably. Redesigning of the bottom penetrator plate, at present, is underway. In this paper, results from numerical modeling only are reported in details. Correlation between experimental-numerical modeling results for the new model will be reported in the near future.

scholarly journals Road Vehicle-Bridge Interaction considering Varied Vehicle Speed Based on Convenient Combination of Simulink and ANSYS

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Helu Yu ◽  
Bin Wang ◽  
Yongle Li ◽  
Yankun Zhang ◽  
Wei Zhang
Keyword(s):  
Reaction Force ◽  
Sudden Change ◽  
Vertical Direction ◽  
Dynamic Responses ◽  
Force Model ◽  
Vertical Acceleration ◽  
Vehicle Speed ◽  
Road Vehicle ◽  
The Road ◽  
Bridge Model

In order to cover the complexity of coding and extend the generality on the road vehicle-bridge iteration, a process to solve vehicle-bridge interaction considering varied vehicle speed based on a convenient combination of Matlab Simulink and ANSYS is presented. In this way, the road vehicle is modeled in state space and the corresponding motion equations are solved using Simulink. The finite element model for the bridge is established and solved using ANSYS. The so-called inter-history iteration method is adopted to realize the interaction between the vehicle model and the bridge model. Different from typical method of road vehicle-bridge interaction in the vertical direction, a detailed longitudinal force model is set up to take into account the effects of varied vehicle speed. In the force model, acceleration and braking of the road vehicle are treated differently according to their mechanical nature. In the case studies based on a simply supported beam, the dynamic performance of the road vehicle and the bridge under varied vehicle speeds is calculated and discussed. The vertical acceleration characteristics of the midpoint of beam under varied vehicle speed can be grouped into two periods. The first one is affected by the load transform between the wheels, and the other one depends on the speed amplitude. Sudden change of the vertical acceleration of the beam and the longitudinal reaction force are observed as the wheels move on or off the bridge, and the bridge performs different dynamic responses during acceleration and braking.

scholarly journals Experimental study on dynamic response of model shield tunnel induced by moving-axle loads of subway train

2018 ◽  
Vol 14 (10) ◽  
pp. 155014771880278
Author(s):  
Mengxi Zhang ◽  
Xiaoqing Zhang ◽  
Lei Li ◽  
Chengyu Hong
Keyword(s):  
Time History ◽  
Vertical Displacement ◽  
Wheel Speed ◽  
Dynamic Responses ◽  
Scale Model ◽  
Shield Tunnel ◽  
Laboratory Model ◽  
Cover Depth ◽  
Axle Loads ◽  
Subway Train

A new testing method was introduced to apply moving-axle loads of a subway train on a track structure. In order to investigate the dynamic responses of the shield tunnel subjected to moving-axle loads, a series of laboratory model tests were conducted in a 1/40 scale model tunnel. The influences of the axle load, the wheel speed, and the cover depth of the shield tunnel on the vertical displacement and acceleration of the lining were presented and discussed. Parametric studies revealed that the vertical displacement–time history of the lining presents a “W” shape due to the combined action of two axles of a bogie. The peak value of the vertical displacement increased with the axle load linearly, while it decreased with the increase in the cover depth. Moreover, response time of the displacement decreased with the increase in the wheel speed, but the peak values remained stable at the same level. Finally, a three-dimensional dynamic finite element model was adopted to simulate the movement of the axle loads and calculate the responses of the lining. The numerical results analysis agrees well with experimental results.

scholarly journals The primordial black hole formation criterion re-examined: Parametrisation, timing and the choice of window function

2019 ◽  
Vol 29 (02) ◽  
pp. 2030002 ◽  
Author(s):  
Sam Young
Keyword(s):  
Black Hole ◽  
Density Perturbation ◽  
Density Contrast ◽  
Smoothing Function ◽  
Primordial Black Hole ◽  
Curvature Perturbation ◽  
Order Of Magnitude ◽  
Horizon Limit ◽  
First Time ◽  
Peak Value

In this paper, the criterion used to determine whether a density perturbation will collapse to form a primordial black hole (PBH) is re-examined in respect of its use to determine the abundance of PBHs. There is particular focus on which parameter to use, the time at which the abundance should be calculated, and the use of different smoothing functions. It is concluded that, with the tools currently available, the smoothed density contrast should be used rather than the peak value, and should be calculated from the time-independent component of the density contrast in the super-horizon limit (long before perturbations enter the horizon) rather than at horizon crossing. For the first time, the effect of the choice of smoothing function upon the formation criterion is calculated, and, for a given abundance of PBHs, it is found that the uncertainty in the amplitude of the power spectrum due to this is [Formula: see text], an order of magnitude smaller than that suggested by previous calculations. The relation between the formation criterion stated in terms of the density contrast and the curvature perturbation [Formula: see text] is also discussed.

scholarly journals A Determination Method for Gait Event Based on Acceleration Sensors

Sensors ◽  
2019 ◽  
Vol 19 (24) ◽  
pp. 5499 ◽  
Author(s):  
Chang Mei ◽  
Farong Gao ◽  
Ying Li
Keyword(s):  
Motion Capture ◽  
Inertial Sensors ◽  
Gait Recognition ◽  
Three Dimensional ◽  
High Standard ◽  
Vertical Displacement ◽  
Human Gait ◽  
Vertical Acceleration ◽  
Acceleration Signal ◽  
Acceleration Sensors

A gait event is a crucial step towards the effective assessment and rehabilitation of motor dysfunctions. However, for the data acquisition of a three-dimensional motion capture (3D Mo-Cap) system, the high cost of setups, such as the high standard laboratory environment, limits widespread clinical application. Inertial sensors are increasingly being used to recognize and classify physical activities in a variety of applications. Inertial sensors are now sufficiently small in size and light in weight to be part of a body sensor network for the collection of human gait data. The acceleration signal has found important applications in human gait recognition. In this paper, using the experimental data from the heel and toe, first the wavelet method was used to remove noise from the acceleration signal, then, based on the threshold of comprehensive change rate of the acceleration signal, the signal was primarily segmented. Subsequently, the vertical acceleration signals, from heel and toe, were integrated twice, to compute their respective vertical displacement. Four gait events were determined in the segmented signal, based on the characteristics of the vertical displacement of heel and toe. The results indicated that the gait events were consistent with the synchronous record of the motion capture system. The method has achieved gait event subdivision, while it has also ensured the accuracy of the defined gait events. The work acts as a valuable reference, to further study gait recognition.

Vibration characteristics simulation and comparison of traditional cab system model and seat–cab coupled model for trucks

2019 ◽  
Vol 10 (03) ◽  
pp. 1950013 ◽  
Author(s):  
Leilei Zhao ◽  
Yuewei Yu ◽  
Changcheng Zhou ◽  
Simon Feng
Keyword(s):  
Angular Acceleration ◽  
Coupled Model ◽  
Random Excitation ◽  
Vibration Characteristics ◽  
Dynamic Responses ◽  
System Model ◽  
Vertical Acceleration ◽  
Excitation Condition ◽  
Vertical Excitation ◽  
Excitation Conditions

To define the application fields of the traditional cab system model and the seat–cab coupled model, this paper mainly aims to investigate the differences of the vibration characteristics of the two models. First, the two models and their motion equations were introduced. Then, based on the mechanical parameters of the seat and cab system for a truck, the transmissibility characteristics of the two models were analyzed. The results show that the traditional model can relatively accurately predict the pitch and roll vibration characteristics of the real seat–cab system. However, it overvalues the vertical vibration transmitted from the front suspensions of the cab. Third, the typical excitation conditions and the measuring points were selected. Finally, under the typical excitation conditions, the dynamic responses of the measuring points were calculated. The results show that under the vertical excitation condition, the dynamic responses of the two models have obvious differences. Under the roll excitation condition and the pitch excitation condition, the roll responses and the pitch responses of the cab between the two models show almost no obvious difference. Under the random excitation condition, the vertical acceleration responses have relatively larger deviations between the two models, however, the angular acceleration responses are almost the same. For the preliminary design of the cab system, the traditional cab system model can be used. However, for the accurate design and the optimization of the seat–cab system, the seat–cab coupled model is recommended.

The Seismic Dynamic Response on the Steel Spatial Arch Truss with 60 m Span and 0.4 Rise-Span Ratio

2011 ◽  
Vol 368-373 ◽  
pp. 850-853
Author(s):  
Hai Wang Li ◽  
Jing Jing Guo ◽  
Jing Liu
Keyword(s):  
Plastic Hinge ◽  
Vertical Direction ◽  
Nonlinear Effects ◽  
Horizontal Displacement ◽  
Vertical Displacement ◽  
Dynamic Responses ◽  
Peak Acceleration ◽  
Displacement Ductility ◽  
Earthquake Action ◽  
Material Nonlinear

In this paper, the elasto-plastic dynamic analysis on the steel spatial arch truss with 60 m span and 0.4 rise-span ratio is carried out under earthquake wave with SAP2000. In the analyses, the geometric and material nonlinear effects are considered at the same time based on the plastic-hinge theory. Under the action of EL wave with the peak increasing gradually, its elasto-plastic dynamic responses have been obtained. The results show that its failure mode under the earthquake action is elasto-plastic dynamic buckling; that its critical peak acceleration of EL earthquake wave when applied in horizontal direction is 808.5 gal, and is 789.0 gal when applied in vertical direction; The ratio of its maximal node horizontal displacement and its structural height is 1/259, and its displacement ductility coefficient is 1.071; The ratio of its maximal node vertical displacement and its structural span is 1/736, and its displacement ductility coefficient is 1.105.

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