Train Suspension Research Articles

Does right ventricular remodeling in elite athletes persist years after training cessation?

Abstract Funding Acknowledgements Type of funding sources: None. Background Intense and prolonged exercise training induces morpho-functional cardiac changes, known as "athlete’s heart". The physiologic nature of this cardiac remodeling has been questioned and data on reversibility of cardiac remodeling, especially of the right ventricle (RV), after the suspension of high intensity training are scarce. Purpose To describe cardiac morpho-functional changes by echocardiography in a group of Olympic athletes prior the Olympic games (T1) and years after cessation of their competitive athletic career (T2). Methods Endurance athletes evaluated prior their participation to the Olympic games (edition 2004-2008-2012) and after cessation of their athletic career (> 3 years of cessation of intensive exercise training) were invited to be evaluated at our Institute. 12-lead ECG, exercise ECG test and echocardiogram were performed. Echocardiogram parameters at T1 and T2 were compared including left ventricle (LV) and RV dimension, systolic and diastolic function. Results 25 athletes were enrolled (mean age 47±2 years). The mean time from the end of their agonistic activity was 12 ± 7 years. No differences in terms of LV dimensions and function were observed (Table). Veterans showed a significant decrease in RV dimensions and improvement in function at T2 compared to T1. Conclusion After suspension of competitive training, Veteran athletes showed reverse remodeling of the right ventricle compared with the evaluation during the peak training by echocardiography.

Series-parallel mechanical circuit synthesis of a positive-real third-order admittance using at most six passive elements for inerter-based control

This paper investigates the circuit synthesis problem for a certain positive-real bicubic (third-order) admittance with a simple pole at the origin (s=0) to be realizable as a one-port series-parallel damper-spring-inerter circuit consisting of at most six elements, where the results can be directly applied to the design and physical realization of inerter-based control systems. Necessary and sufficient conditions for such a specific bicubic admittance to be realizable by a one-port passive series-parallel mechanical circuit containing at most six elements are derived, and a group of mechanical circuit configurations covering the whole set of realizability conditions are presented together with element value expressions. The conditions and element value expressions are related to the admittance coefficients and the roots of certain algebraic equations. The circuit synthesis results of this paper are illustrated by several numerical examples including the control system design of a train suspension system. Any realization circuit in this paper contains much fewer passive elements than the ten-element realization circuit by the well-known Bott-Duffin circuit synthesis approach. The investigations of this paper can contribute to the theory of circuit synthesis and many other related fields.

Electromagnetic Modelling and Ripple Suppression of Asymmetrical Ground Coil Integrated With Propulsion, Levitation and Guidance For EDS Train

Integrated ground coils realize combination of propulsion, levitation and guidance (PLG) functions for electrodynamic suspension (EDS) train, which is of great significance for cost-saving and cycle-shortening in the process of construction. In this paper, a high-efficient analytical model, emphatically considering the geometrical asymmetry of integrated ground coil, is built to calculate electromagnetic performance of PLG system. Afterwards, to suppress the ripple of electromagnetic force, a multi-objective optimization is employed to improve the operating quality and output performance of PLG system. Resorting to proposed analytical model, the Pareto solution set is generated on the basis of Non-Dominated Sorting Genetic Algorithm (NSGA-II) method. Finally, the representative solutions are extracted by K-means clustering method, where these optimized schemes are compared with the initial scheme. The optimized schemes indicate that asymmetrical structure of ground coil could effectively reduce force ripple, thereby increasing the performance of PLG system.

Adaptive fault-tolerant control of high-speed maglev train suspension system with partial actuator failure: design and experiments

Adaptive fault-tolerant control of high-speed maglev train suspension system with partial actuator failure: design and experiments

Mapping the Needs of Different Groups of Athletes of the City of Zagreb and the Republic of Croatia During Crisis Situations (Covid – 19 and Earthquake) – Athlete Perspective

This paper was created as part of the project "Trešnjevka Wrestlers for Civil Society Sports Organizations (SOCD) in Crisis Situations." with a specific ambition - to pursue improving the capacity of civil society organizations to respond to the needs of the local community in crisis situations. For this purpose and as one of the project activities, the mapping of the needs of different groups of athletes and sports workers of the City of Zagreb and the Republic of Croatia during the crises of Covid – 19 and the earthquake is carried out. This research used a qualitative approach that includes focus group pre-research. To ensure broad coverage of the researched topic and for the purpose of heterogeneity, research deliberately focused on 17 different groups of sport. The structure of pre-research participants who were selected intentionally from 17 sports resulted in a total of 17 athletes. All respondents are athletes and adults who have consented to participate in the survey. Qualitative research was conducted through pre-questionnaires and semi-structured interviews and the survey was guided from February to April 2022. Each athlete belonging to a defined sports community (club or federation) was examined separately. Respondents were introduced to the aim of the research and general questions asked and were also informed about the confidentiality of the answers. Collected data materials were processed by comparative analysis. Alternate observation of the responses, similarities and differences among them, and according to the superior aspect of the research (improving the capacity of civil society organizations to provide an effective response to the needs of the local community in crisis situations) along with the intensity of life quality for athletes managing sport during the pandemic, led to the following question: What needs have been identified by different groups of athletes of the City of Zagreb and the Republic of Croatia during crises (Covid - 19 and earthquakes)? The most frequent declarations are associated with impaired training continuity or suspension of training due to epidemiological measures and earthquake-damaged infrastructure, cancellation of the competitions and a decrease in motivation. 
 Keywords: occurrences, crisis situations, athletes, needs assessment, quality of life

Fuzzy Linear Active Disturbance Rejection Control Method for Permanent Magnet Electromagnetic Hybrid Suspension Platform

The permanent magnetic suspension (PMS) train has distinct advantages in reducing energy consumption and increasing the suspension air gap. Aiming at the problems of uncontrollable magnetic field and underdamping of the PMS system, the electromagnetic damping structure is introduced, and a fuzzy linear active disturbance rejection control (Fuzzy-LADRC) method with an air gap deviation integrator is proposed. Firstly, the permanent magnet electromagnetic hybrid suspension (PEMS) system is constructed, and the model analysis is carried out to prove that the system is controllable and observable, and the hardware experimental platform is built. Secondly, a LADRC method is designed based on the model of the platform suspension control unit, and fuzzy control is introduced into the LADRC state error feedback control theory for parameter self-tuning to improve the adaptability and robustness of the platform. At the same time, an air gap deviation integrator is introduced to further improve the control accuracy. Finally, the comparison experiments with LADRC and PID control methods are carried out in terms of stability, anti-interference, robustness and adaptability. The experimental results show that the proposed Fuzzy-LADRC method has the best control effect. It provides practical reference for improving the stability of the PMS train.

Data-Driven Nonlinear Iterative Inversion Suspension Control

The commercial operation of the maglev train has strict requirements for the reliability and safety of the suspension control system. However, due to a large number of unmodeled dynamics of the suspension system, it is difficult to obtain the precise mathematical model of the suspension system. After the suspension system has been operated for a long time with high load, the system model will change due to the wear, aging and failure of components, as well as the settlement of the line and track. The control performance is degraded. Therefore, this paper proposes a data-driven nonlinear iterative inversion suspension control algorithm, which can achieve high-precision tracking performance recovery control after control performance degradation without depending on the suspension system model. The control performance of the suspension system is improved by learning the measured data of the historical suspension system, and the fast convergence of the tracking error and high-precision stable suspension control are realized in the presence of unmodeled dynamics and external noise interference. Based on the historical suspension data of the maglev train suspension control system, the inverse dynamics model of the suspension system is identified by iterative inversion learning based on data drive, and the suspension control framework based on iterative inversion is designed. Then, the nonlinear input update strategy is used to realize the rapid convergence of the learning process. Finally, the simulation experiment of the maglev train suspension system and the physical experiment of the maglev system experimental platform are combined. It is verified that the proposed levitation control algorithm can achieve high-precision fast tracking performance recovery control after the system control performance degrades under noise environment.

Harmonic Magnetic Field Analysis Method and Modeling of Double-Sided Air-Cored Superconducting Linear Synchronous Motor for EDS Train

This study introduces a novel methodology based on the idea of double Fourier series and coil segmentation, performed based on governing equations, with harmonic magnetic field analysis of a double-sided air-cored superconducting linear synchronous motor for electrodynamic suspension train. This method can solve the harmonic magnetic field generated by arbitrarily shaped coils. First, with rectangular-shaped coils and race-track-shaped coils as examples, the process of calculating harmonic magnetic field using the proposed method is introduced comprehensively, and the influence of the end effect is also considered. Second, based on the solution results of the harmonic magnetic field, a modeling method that can quickly solve no-load superconducting flux linkage, no-load back EMF, and three-dimensional (3-D) electromagnetic forces without losing accuracy is presented, which is verified by finite element simulation. Finally, two static tests are designed. The effectiveness of the proposed method is verified by the test results of static thrust and static normal force.

Vehicle-track coupled dynamics model for superconducting electrodynamic suspension train

In the previous studies of superconducting EDS train, the magneto-electric coupling between superconducting magnets (SCMs) and null-flux coils (NFCs), was equivalent to a vibration system with constant stiffness. This premise has decoupled the magnetic/track interaction and is not able to study the dynamics issues in an accurate and comprehensive level. Therefore, the vehicle-track coupled dynamics model of superconducting EDS train, with magneto-electric-force coupling fully considered, was established to explore the vehicle-track interaction relationship in this paper. A mathematical model based on Newton’s laws and 3-D dynamic co-simulation model were built respectively by Simulink and MATLAB-SIMPACK to compare the operating performances with the time/frequency domain. Meanwhile, the dynamic electromagnetic forces were calculated by dynamic circuit theory rather than merely assuming the constant stiffness. The dynamic responses of suspension vehicle show that, the vibration of carbody and frame are mainly concentrated about 1 Hz and 5 Hz respectively. The use of equivalent model in the previous studies has overestimated the negotiation capacity of superconducting EDS train. Furthermore, the vertical vibration accelerations of frame in the coupled model are relatively larger, whereas the lateral vibration is comparatively smaller. Therefore, the electromagnetic calculation of superconducting EDS train with constant stiffness overestimates/underestimates the dynamic performances.

Evaluation of the Quality of Clinical Education and the Clinical Self-efficacy of Nursing Students during the COVID-19 Pandemic

Background: Clinical education is the most important part of the education of nursing, operating room, and anesthesia students. During the COVID-19 pandemic and the suspension of clinical training, these students became very concerned. Nursing schools also limited clinical education to create a balance between the educational needs and safety of students. Therefore, the present study aimed to investigate the effect of changing clinical education conditions during the COVID-19 pandemic on the quality of clinical education and the clinical self-efficacy of nursing, operating room, and anesthesia students in Tehran, Iran. Methods: This descriptive cross-sectional study was conducted in 2020 on 277 seventh and eighth-semester nursing, operating room, and anesthesia students in Tehran, Iran. Students were selected by simple random sampling using a random number table. The study tools included the demographic questionnaire, the clinical education quality questionnaire, and the clinical self-efficacy questionnaire, which were sent to the participants via WhatsApp and Telegram after confirming their validity and reliability. Results and Discussion: 64.30% of students were female, and the mean age was 23.59±3.49. The mean of total scores for the quality of clinical education and clinical self-efficacy was equal to 57.38±12.43 and 104.88±23.01, respectively. 57% of students considered moderate the level of the quality of clinical education and 51.60% of them moderate the level of clinical self-efficacy. The total score for clinical self-efficacy had a significant correlation with the quality of clinical education (r=0.12, P-value=0.04). Conclusion: The use of new educational methods, planning the course based on the needs of learners and in accordance with the conditions, and increasing the capability and the clinical self-efficacy of nursing students should be considered by nursing professors.

ВЛИЯНИЕ ПАРАМЕТРОВ ГОРИЗОНТАЛЬНЫХ СВЯЗЕЙ РЕССОРНОГО ПОДВЕШИВАНИЯ СКОРОСТНЫХ ЭЛЕКТРОПОЕЗДОВ НА УСТОЙЧИВОСТЬ ДВИЖЕНИЯ

The article considers the design, as well as a regression analysis of the spread of values of horizontal elastic-dissipative connections of the 1st and 2nd stages of spring suspension of high-speed and high-speed electric trains. In order to assess the influence of the longitudinal and transverse stiffness of the wheelset connections with the bogie frame, as well as the dissipation of the longitudinal hydraulic vibration damper of the 2nd stage of suspension on the stability of the crew movement, a numerical study was carried out using a mathematical model of a trailer car of the Sapsan electric train in the Universal Mechanism software package

CARACTERÍSTICAS DAS PRINCIPAIS LESÕES ESPORTIVAS EM ATLETAS DE ALTO DESEMPENHO

ABSTRACT Introduction The focus of attention in high-performance athlete injuries tends to be on physical recovery, neglecting psychological factors and their practical social impacts on the rehabilitation of the injured athlete. In this phase, giving attention to the importance of athletes’ thoughts, emotions, and motivation can speed up the biopsychosocial rehabilitation process. Objective To analyze the characteristics involved in the major sports injuries of high-level athletes to provide a reference for athletes and coaches during recovery. Methods This article analyzes through bibliographic research the characteristics of the major sports injuries in high-level athletes, including physiological, psychological, and social factors. Results The physical impact of injuries requires patience and persistence for recovery, including additional muscle strengthening to compensate for the loss of residual joint proprioception, ensuring performance recovery. Mental factors such as insecurity when returning from games, reduced self-confidence, and fear of hurting the team must be worked through in parallel in multi-professional care and during long recovery periods. Conclusion Sports injuries can occur in athletes of all levels. For elite athletes, the impact of injuries, especially severe ones that need to interrupt training or even surgery, will lead to forced suspension of training or competition, preventing the improvement of sports performance, decreasing the quality of the sports career, and may even lead to physical or psychological disability in severe cases. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Study on the Hybrid Damping Semi-active Control of Secondary Suspension of Superconducting Electrodynamic Suspension Train

Study on the Hybrid Damping Semi-active Control of Secondary Suspension of Superconducting Electrodynamic Suspension Train

Genetic Algorithm Tuned Super Twisting Sliding Mode Controller for Suspension of Maglev Train With Flexible Track

The suspension air-gap of Maglev train needs controller for it is inherently unstable and highly nonlinear. To maintain a high quality of ride, comfort and safety for the passengers the train suspension controller must maintain the suspension air-gap. During operation the suspension air-gap of a Maglev train is only in millimeters. This easily causes instability under excitation of nonlinear load and track tiny deformation. Additionally, a track with a low stiffness will experience larger bending displacement and result in high vibrations. A high stiffness track experience minor bending displacement, which will diminish the vibration and improve riding quality. Unfortunately, using high stiffness guideway track is expensive. Instead, by designing a good controller the low stiffness material can be used. In this paper genetic algorithm tuned super twisting sliding mode control is proposed for it offers a good controlling ability since it is insensitive to external disturbance, parameter variation and has a fast dynamic response. The proposed controllers are tested under different circumstances, i.e., Maglev train with rigid track and with flexible track under variable load and external random disturbance.

A new suppression strategy of pitching vibration based on the magnetic-electric-mechanical coupling dynamic model for superconducting EDS transport system

The superconducting electrodynamic suspension (EDS) train is suitable for high-speed maglev rail transit because of its low drag force, strong levitation force, large suspension gap, and so on. However, the electromagnetic forces of four pairs of superconducting coils on one bogie are dynamically unequal in practical operation. This causes the bogie to vibrate in the pitching axis, which affects the train system's safety, stability, and comfort. Therefore, proposing an appropriate strategy to suppress the bogie pitching vibration is significant. First, based on the dynamic circuit theory, energy method and rigid body dynamics, the magnetic-electric-mechanical coupling dynamic model of eight superconducting high-field coils in the bogie and ground null-flux coils was established to explore the characteristics of fluctuating and unequal electromagnetic forces. The synchronous current and motion responses were further calculated using the Runge-Kutta algorithm. Second, the bogie's vibration characteristics were analyzed and the reasons for the vertical and pitching vibration were discussed. And the accuracy of the model was verified by comparing the levitation force with the experiment data. Third, a non-uniform exciting currents supply strategy for the superconducting coils was proposed under the comprehensive evaluation of the suppressing effect on the pitching vibrations. Finally, several cases were given to prove the effectiveness of the strategy. The results show that the total electromotive force increased by 0.005% after adopting the proposed non-uniform exciting currents supply strategy. But the minimum and maximum amplitude of pitching vibration and the growth rate of pitching vibration decreased by 97.00%, 95.76%, and 81.45%, respectively. This new strategy can effectively suppress the pitching vibration of the bogie without changing the already-designed mechanical structure. This established magnetic-electric-mechanical coupling dynamic model and the suppression strategy provide reference and a new idea for the superconducting EDS system's safety, stability, and comfort.

Nonlinear Robust Composite Levitation Control for High-Speed EMS Trains With Input Saturation and Track Irregularities

Unavoidable track irregularities continuously excite a traveling high-speed electromagnetic suspension (EMS) train. This issue deteriorates the levitation performances such as stability and comfortability. A robust levitation controller is critical for the EMS unit to suppress irregularities. In this work, a novel composite control scheme is proposed for high-speed maglev trains. It combines a fixed-time disturbance observer (FTDO) and a global finite-time controller (FTC). The FTDO is designed to estimate irregularities precisely within desired bandwidth, while the FTC is to address the fast dynamics of the levitation system of a high-speed maglev train. In addition, the command filter is integrated to increase the practicability of the composite control scheme. Theoretical analysis establishes the stability of the whole system. With ideal irregularity models and the field data measured from a commercial line, numerical simulations under various operation scenarios, including high speed, time-varying speed, gust and slope, verify that the proposed control scheme improves the air gap response while maintaining the stationarity of primary levitation and the ride comfortability for passengers. The simulations on a full bogie with load also demonstrate effectiveness of the proposed scheme.

Classroom Teaching Design of Alpine Skiing Based on Virtual Reality Technology

Due to the limitation of venues for seasonal projects, it is a great challenge for students to adapt and maintain their sports status in non-snow seasons. Therefore, it is very important to do well in the non-snow season Lu-snow conversion training. At this stage, when the school formulates the teaching work plan for the school year, due to the limitation of the venue, the non-snow season Lu-snow conversion training is mainly based on physical training, while special skills training is supplemented, and there are problems such as poor teaching effect, insufficient teaching methods, and single practice means. At the same time, due to the reduction or even suspension of technical movement training in non-snow seasons, the teaching of alpine skiing lacks continuity and systematicity, which affects teaching effect. With the application of virtual reality technology in alpine skiing courses, this study conducts experimental research on the teaching and training effects in non-snow seasons, demonstrates the advantages of virtual reality technology in alpine skiing teaching and training, and optimizes the conversion of alpine skiing between land and snow in non-snow seasons.

3-D Modeling of Current Decay in a Closed HTS Racetrack Coil Under Traveling Magnetic Fields

High temperature superconducting (HTS) magnets working in persistent current mode (PCM) have shown a superior potential in electrodynamic suspension (EDS) train applications. When exposed to the external traveling magnetic fields generated by the propulsion coils, the on-board HTS coils used as the secondary of synchronous motor will suffer a non-negligible loss resulting from dynamic resistance which is much larger than caused by joint resistance. In this work, we build a 3-D finite element model of a real scale HTS racetrack coil to predict its behaviour. In the modeling, homogenization technique and the symmetry plane are adopted for accelerating computation, and the proper boundary conditions are used for field-cooling excitation as well as applying traveling fields. Firstly, the effectiveness of the model has been validated by comparing with experimental results of a small prototype. Then based on the method, a real scale HTS racetrack magnet model with the symmetry modified as to adapt the EDS scenario is built for investigating the current decay property varying with the external fields. Moreover, the effect mechanism of the instantaneous AC loss on the current attenuation is deeply analyzed.

Strategies for improving the force performance of a superconducting linear synchronous motor

Combined with superconducting technology, an electrodynamic suspension train can reach a higher traveling speed by taking advantage of the strong magnetic field generated by high-temperature superconducting (HTS) magnets. However, a HTS linear synchronous motor (LSM) in a propulsion system typically uses an air-core structure to reduce the normal force. As a result, excessive propulsive force ripple occurs due to magnetic circuit divergence and a large air gap, which leads to an uncomfortable ride and unexpected mechanical resonance. To reduce this ripple, this study first improves the traditional short-pitch winding structure of the stator. By staggering the double-layer coils of the stator, the ripples of the magnetic flux density generated by the upper and lower coils change from superposition to suppression. Then, the propulsive force of a pair of pole magnets of the HTS-LSM under this structure is analyzed, and its primary ripple frequency is 6 times the fundamental frequency. By installing two pairs of magnets in a bogie and staggering them by a 30° electrical angle, the peak and valley of the propulsive force of the two magnets are staggered so that the total propulsive force waveform of the bogie can be smoothed as much as possible. Concurrently, the AC loss generated by the alternating magnetic field on the HTS magnets can be reduced. Also, this study investigates the influence of the short pitch factor on the propulsive force, and the ripple can be suppressed by reducing the factor.

Fast Optimization of Null-Flux Coils for Superconducting Electrodynamic Suspension Train With RSM and AMGA

Fast Optimization of Null-Flux Coils for Superconducting Electrodynamic Suspension Train With RSM and AMGA