scholarly journals Study on the Influence of the Marshalling Position of Vehicles Without Braking Function on the Safety of Empty Freight Trains Under Braking Condition

2020 ◽  
Author(s):  
Yiping Jiang ◽  
Chunhui Yang ◽  
Shimin Luo
Keyword(s):  
System Dynamics ◽  
Dynamic Model ◽  
Dynamic Performance ◽  
Safety Performance ◽  
Front Part ◽  
Freight Train ◽  
Derailment Coefficient ◽  
Coupling System ◽  
Coupling Dynamics ◽  
Unloading Rate

In order to study the influence of the position of without braking function on the safety of empty freight trains, a dynamic model of the locomotive and vehicle-track coupling system was established based on the theory of vehicle system dynamics and the theory of train-track coupling dynamics. And the safety indicators of the empty freight train’s lateral wheelset force, derailment coefficient, and wheel unloading rate were analyzed and compared with the dynamic safety indicators of the empty freight trains with normal braking function, while the vehicles without braking function located in the front, middle and rear parts of the freight train. The results show that during the service brake conditions, whether there are vehicles without braking function or not, the safety performance of the empty freight train is not much different, and all meet the requirements of the GB5599-2019 standard, the safety performance of the vehicles without braking function is not significantly different from that of the normal vehicles, the lateral wheelset force and the derailment coefficient are slightly greater than those in other parts while the vehicles without braking function located at the front part of the train, and the dynamic performance is not much different when the vehicles without braking function located in the middle and rear of the train.

Inductor Saturation Compensation in Three-Phase Three-Wire Voltage-Source Converters via Inverse System Dynamics-I

2020 ◽  
Author(s):  
Ziya Özkan ◽  
Ahmet Masum Hava
Keyword(s):  
Dynamic Model ◽  
Dynamic Performance ◽  
Current Control ◽  
Inverse System ◽  
Voltage Source ◽  
Voltage Source Converter ◽  
Two Phase ◽  
Inverse Dynamic ◽  
Three Phase ◽  
Steady State Current

In three-phase three-wire (3P3W) voltage-source converter (VSC) systems, utilization of filter inductors with deep saturation characteristics is often advantageous due to the improved size, cost, and efficiency. However, with the use of conventional synchronous frame current control (CSCC) methods, the inductor saturation results in significant dynamic performance loss and poor steady-state current waveform quality. This paper proposes an inverse dynamic model based compensation (IDMBC) method to overcome these performance issues. Accordingly, a review of inductor saturation and core materials is performed, and the motivation on the use of saturable inductors is clarified. Then, two-phase exact modelling of the 3P3W VSC control system is obtained and the drawbacks of CSCC have been demonstrated analytically. Based on the exact modelling, the inverse system dynamic model of the nonlinear system is obtained and employed such that the nonlinear plant is converted to a fictitious linear inductor system for linear current regulators to perform satisfactorily.

Front steering design guidelines formulation for e-scooters considering the influence of sitting and standing riders on self-stability and safety performance

2021 ◽  
pp. 095440702199217
Author(s):  
Milan Paudel ◽  
Fook Fah Yap
Keyword(s):  
Preventive Measures ◽  
Recent Trend ◽  
Dynamic Performance ◽  
Design Guidelines ◽  
Safety Performance ◽  
Design Parameters ◽  
Single Track ◽  
Standing Posture ◽  
Last Mile ◽  
Current Design

E-scooters are a recent trend and are viewed as a sustainable solution to ease the first and last mile problem in modern transportation. However, an alarming rate of accidents, injuries, and fatalities have caused a significant setback for e-scooters. Many preventive measures and legislation have been put on the e-scooters, but the number of accidents and injuries has not reduced considerably. In this paper, the current design approach of e-scooters has been analyzed, and the most common range of design parameters have been identified. Thereafter, validated mathematical models have been used to quantify the performance of e-scooters and relate them with the safety aspects. Both standing and seated riders on e-scooters have been considered, and their influence on the dynamic performance has been analyzed and compared with the standard 26-in wheel reference safety bicycle. With more than 80% of the accidents and injuries occurring from falling or colliding with obstacles, this paper tries to correlate the dynamics of uncontrolled single-track vehicles with the safety performance of e-scooters. The self-stability, handling, and braking effect have been considered as major performance matrices. The analysis has shown that the current e-scooter designs are not as stable as the reference safety bicycle. Moreover, these e-scooters have been found unstable within the most common range of legislated riding velocity. The results corroborate with the general perception that the current designs of e-scooters are less stable, easy to lose control, twitchy, or wobbly to ride. Furthermore, the standing posture of the rider on the e-scooter has been found dangerous while braking to avoid any disturbances such as potholes or obstacles. Finally, the front steering design guidelines have been proposed to help modify the current design of e-scooters to improve the dynamic performance, hence the safety of the e-scooter riders and the surroundings.

scholarly journals Numerical Investigation on Hydrodynamic Performance of a Portable AUV

2021 ◽  
Vol 9 (8) ◽  
pp. 812
Author(s):  
Lin Hong ◽  
Renjie Fang ◽  
Xiaotian Cai ◽  
Xin Wang
Keyword(s):  
Numerical Investigation ◽  
Dynamic Model ◽  
Autonomous Underwater Vehicle ◽  
Dynamic Performance ◽  
Plane Motion ◽  
Hydrodynamic Performance ◽  
Wave Forces ◽  
Modeling And Control ◽  
Experiment Platform ◽  
Cfd Method

This paper conducts a numerical investigation on the hydrodynamic performance of a portable autonomous underwater vehicle (AUV). The portable AUV is designed to cruise and perform some tasks autonomously in the underwater world. However, its dynamic performance is strongly affected by hydrodynamic effects. Therefore, it is crucial to investigate the hydrodynamic performance of the portable AUV for its accurate dynamic modeling and control. In this work, based on the designed portable AUV, a comprehensive hydrodynamic performance investigation was conducted by adopting the computational fluid dynamics (CFD) method. Firstly, the mechanical structure of the portable AUV was briefly introduced, and the dynamic model of the AUV, including the hydrodynamic term, was established. Then, the unknown hydrodynamic coefficients in the dynamic model were estimated through the towing experiment and the plane-motion-mechanism (PMM) experiment simulation. In addition, considering that the portable AUV was affected by wave forces when cruising near the water surface, the influence of surface waves on the hydrodynamic performance of the AUV under different wave conditions and submerged depths was analyzed. Finally, the effectiveness of our method was verified by experiments on the standard models, and a physical experiment platform was built in this work to facilitate hydrodynamic performance investigations of some portable small-size AUVs.

Dynamic Modeling of Planar Flexible Multi-Link Manipulators with Accounting for both Link Foreshortening and Link Material Damping

2011 ◽  
Vol 199-200 ◽  
pp. 19-24
Author(s):  
Jin Fu Zhang
Keyword(s):  
Dynamic Model ◽  
Dynamic Modeling ◽  
Dynamic Performance ◽  
Material Damping ◽  
Motion Responses ◽  
Case Simulation ◽  
Tip Mass ◽  
Lagrange Approach

In order to investigate dynamic performance of flexible multi-link manipulators more exactly, establishing the dynamic model with accounting for link foreshortening and link material damping is needed. In this paper, a new dynamic model for planar flexible multi-link manipulators is established by using Lagrange approach. Both link foreshortening and link material damping are accounted for in this model. As a case simulation, this model is applied to a planar flexible two-link manipulator with a tip mass, and the motion responses of the manipulator are obtained using Gear method.

scholarly journals The use of tools and approaches of system dynamics in the analysis of the efficiency of BIM implementation and its impact on the management and planning of investments in the construction sector

2019 ◽  
Vol 279 ◽  
pp. 01011
Author(s):  
Martin Hotový
Keyword(s):  
Decision Making ◽  
System Dynamics ◽  
Dynamic Model ◽  
Investment Decision ◽  
Construction Sector ◽  
Strategic Investment ◽  
Investment Projects ◽  
Investment Decision Making ◽  
Proposed Model ◽  
The Impact

This paper presents the use of tools and approaches of system dynamics in the analysis of the efficiency of BIM tools implementation in relation to the management and planning of investments in the construction sector. The dynamic model based on the approach of system dynamics allows to simulate the impact rate (range) of BIM implementation in strategic investment decision-making in the construction sector. Based on the analysis, the key parameters critically affecting the large construction investment projects are determined. The proposed model is implemented as a submodel in the dynamic model designed for potential refinements in the strategic planning of the extent of investments into projects of civil infrastructure of the Czech Republic. The model allows to test different strategies in the virtual world before their implementation. The prediction of future developments based on the proposed model allows to streamline planning and decision-making processes.

The Optimization of Thermocouple Galvanometer System Dynamics When Measuring Temperature Transients

1973 ◽  
Vol 6 (9) ◽  
pp. 384-388
Author(s):  
W. H. McKenzie ◽  
A. H. Richards
Keyword(s):  
System Dynamics ◽  
Natural Frequency ◽  
Time Constant ◽  
Exponential Type ◽  
Natural Frequencies ◽  
Low Voltage ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Ultra Violet ◽  
Dimensional Parameter

When using thermocouples directly connected to ultra-violet galvanometers for recording temperature transients, the low-voltage outputs necessitate the use of galvanometers with low natural frequencies. This puts a limitation on the overall dynamic performance. In a particular application, the user has to select the damping resistor for the galvanometer and the work describes how this is done so that the system is optimised for minimum integrated errors during a transient. The transient considered was of an exponential type which occurs frequently in practice and it is shown that the correct damping ratio and hence damping resistor for the galvanometer depends upon the non-dimensional parameter defined by the product of the natural frequency of the galvanometer and the time constant of the exponential. The results show that the usual value of damping ratio of 0·64 based on minimum sinusoidal distortion has to be modified for best dynamic performance. However, if the non-dimensional parameter is sufficiently large, higher values of damping can be used, which produce a large trace with acceptably small errors.

ICT Powered Strategic Flexibility System Dynamic Model

2014 ◽  
Vol 3 (1) ◽  
pp. 90-110 ◽  
Author(s):  
Agnes Mindila ◽  
Anthony Rodrigues ◽  
Dorothy McCormick ◽  
Ronald Mwangi
Keyword(s):  
System Dynamics ◽  
Strategic Management ◽  
Dynamic Model ◽  
Dynamic Capabilities ◽  
System Dynamic ◽  
Strategic Flexibility ◽  
System Dynamic Model ◽  
Sustainable Competitive Advantage ◽  
Modeling Methodology ◽  
The Impact

Resource-Based View (RBV) of the firm in strategic management literature focuses on firm internal endowments in terms of resources, capabilities and dynamic capabilities for their development. By establishing a learning mechanism, where they are able to adapt and influence the environment, enterprises build a dynamic competence and sustainable competitive advantage. This paper posits that this dynamic competence or strategic flexibility as referred to by strategic management scholars is a phenomenon that needs to be understood by scholars and practitioners in MSEs so that effective intervention programs can be designed. The paper argues that by treating strategic flexibility as a CAS provides a methodology within which models based on known theories in strategic management are employed and tested using system dynamics. The paper also posits that System Dynamics (SD) modeling is a good modeling methodology that captures the dynamism in a CAS. The paper therefore presents a conceptual model for strategic flexibility and a system dynamic model that reveals the variables in play and their relationships. In so doing the paper exposes influence points in the CAS that act as intervention points by practitioners in strategic flexibility of firms. The paper presents ICTs as interventions at the influence points and presents a generic strategic flexibility system dynamic model that brings to play the impact of ICT.

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