Modeling and simulation of high-speed passenger train movements in the rail line

In this paper, we propose a new formula of the real-time minimum safety headway based on the relative velocity of consecutive trains and present a dynamic model of high-speed passenger train movements in the rail line based on the proposed formula of the minimum safety headway. Moreover, we provide the control strategies of the high-speed passenger train operations based on the proposed formula of the real-time minimum safety headway and the dynamic model of highspeed passenger train movements. The simulation results demonstrate that the proposed control strategies of the passenger train operations can greatly reduce the delay propagation in the high-speed rail line when a random delay occurs.

Random dynamic analysis of vertical train–bridge systems under small probability by surrogate model and subset simulation with splitting

The response of the train–bridge system has an obvious random behavior.A high traffic density and a long maintenance period of a track will result in a substantial increase in the number of trains running on a bridge,and there is small likelihood that the maximum responses of the train and bridge happen in the total maintenance period of the track.Firstly,the coupling model of train–bridge systems is reviewed.Then,an ensemble method is presented,which can estimate the small probabilities of a dynamic system with stochastic excitations.The main idea of the ensemble method is to use the NARX(nonlinear autoregressive with exogenous input)model to replace the physical model and apply subset simulation with splitting to obtain the extreme distribution.Finally,the efficiency of the suggested method is compared with the direct Monte Carlo simulation method,and the probability exceedance of train responses under the vertical track irregularity is discussed.The results show that when the small probability of train responses under vertical track irregularity is estimated,the ensemble method can reduce both the calculation time of a single sample and the required number of samples.

DYNAMIC MODEL AND SIMULATION OF A NOVEL ELECTRO-HYDRAULIC FULLY VARIABLE VALVE SYSTEM FOR FOUR-STROKE AUTOMOTIVE ENGINES

在现代四击的引擎技术，可变阀门预定和电梯控制提议潜力为做一台高效的引擎受益。去四击的汽车的引擎的一列新奇电镀物品水力的充分可变的阀门火车被介绍。阀门火车系统和它的动态分析的非线性的数学模型的构造也被介绍。试验性并且模拟结果证明新奇电镀物品水力的阀门火车能完成充分可变的阀门预定和电梯控制。因而，不同负担和速度上的引擎表演将显著地被增加。技术也允许消除传统在汽油引擎和增加引擎设计灵活性扼杀阀门。

Simulation optimization for train movement on a single-track railway

Optimizing train movement has a great significance for railway traffic. In this paper, based on the optimal velocity car-following model, we propose a new simulation model for optimizing train movement in railway traffic. Here a kind of single-track railway is considered. Our aim is to reduce the energy consumption of train movement and ensure the train being on time by controlling the velocity curve of train movement. The simulation results indicate that the proposed model is effective for optimizing train movement. In addition, some major characteristics of train movement can be well captured. This method provides a new way to optimize train movement in railway traffic.

Design and Implementation of Training Simulator for Multi-purpose Construction Crawler

An efficient multi-purpose construction crawler training simulator is developed based on windows platform using digital signal processing,multimedia,sensing,simulation modeling and real-time visualization simulation technologies. The simulator architecture and each part are discussed in this paper. The module designs for data acquisition,dynamic modeling and visual,sound and assess simulation are focused. The system has been put into practice and the satisfactory results are got.

Animal model-based simulation training for three emergent and urgent operations of penetrating thoracic injuries

Purpose:To develop animal models of penetrating thoracic injuries and to observe the effects of the animal model-based training on improving the trainees’performance for emergent and urgent thoracic surgeries.Methods:With a homemade machine,animal models of lung injuries and penetrating heart injuries were produced in porcine and used for training of chest tube drainage,urgent sternotomy,and emergent thoracotomy.Coefficient of variation of abbreviated injury scale and blood loss was calculated to judge the reproducibility of animal models.Five operation teams from basic-level hospitals(group A)and five operation teams from level III hospitals(group B)were included to be trained and tested.Testing standards for the operations were established after thorough literature review,and expert questionnaires were employed to evaluate the scientificity and feasibility of the testing standards.Tests were carried out after the training.Pre-and post-training performances were compared.Post-training survey using 7-point Likert scale was taken to evaluate the feelings of the trainees to these training approaches.Results:Animal models of the three kinds of penetrating chest injuries were successfully established and the coefficient of variation of abbreviated injury scale and blood loss were all less than 25%.After literature review,testing standards were established,and expert questionnaire results showed that the scientific score was 7.30±1.49,and the feasibility score was 7.50±0.89.Post-training performance was significantly higher in both group A and group B than pre-training performance.Post-training survey showed that all the trainees felt confident in applying the operations and were generally agreed that the training procedure were very helpful in improving operation skills for thoracic penetrating injury.Conclusions:Animal model-based simulation training established in the current study could improve the trainees’performance for emergent and urgent thoracic surgeries,especially of the surgical teams from basic-level hospitals.

Effect of RANS Turbulence Model on Aerodynamic Behavior of Trains in Crosswind

The numerical simulation based on Reynolds time-averaged equation is one of the approved methods to evaluate the aerodynamic performance of trains in crosswind.However,there are several turbulence models,trains may present different aerodynamic performances in crosswind using different turbulence models.In order to select the most suitable turbulence model,the inter-city express 2(ICE2)model is chosen as a research object,6 different turbulence models are used to simulate the flow characteristics,surface pressure and aerodynamic forces of the train in crosswind,respectively.6 turbulence models are the standard k-ε,Renormalization Group(RNG)k-ε,Realizable k-ε,Shear Stress Transport(SST)k-ω,standard k-ωand Spalart-Allmaras(SPA),respectively.The numerical results and the wind tunnel experimental data are compared.The results show that the most accurate model for predicting the surface pressure of the train is SST k-ω,followed by Realizable k-ε.Compared with the experimental result,the error of the side force coefficient obtained by SST k-ωand Realizable k-εturbulence model is less than 1%.The most accurate prediction for the lift force coefficient is achieved by SST k-ω,followed by RNG k-ε.By comparing 6 different turbulence models,the SST k-ωmodel is most suitable for the numerical simulation of the aerodynamic behavior of trains in crosswind.

Discrete-time movement model of a group of trains on a rail line with stochastic disturbance

This paper presents a discrete-time model to describe the movements of a group of trains, in which some operational strategies, including traction operation, braking operation and impact of stochastic disturbance, are defined. To show the dynamic characteristics of train traffic flow with stochastic disturbance, some numerical experiments on a railway line are simulated. The computational results show that the discrete-time movement model can well describe the movements of trains on a rail line with the moving-block signalling system. Comparing with the results of no disturbance, it finds that the traffic capacity of the rail line will decrease with the influence of stochastic disturbance. Additionally, the delays incurred by stochastic disturbance can be propagated to the subsequent trains, and then prolong their traversing time on the rail line. It can provide auxiliary information for rescheduling trains When the stochastic disturbance occurs on the railway.

Reservoir lithology stochastic simulation based on Markov random fields

Markov random fields(MRF) have potential for predicting and simulating petroleum reservoir facies more accurately from sample data such as logging, core data and seismic data because they can incorporate interclass relationships. While, many relative studies were based on Markov chain, not MRF, and using Markov chain model for 3D reservoir stochastic simulation has always been the difficulty in reservoir stochastic simulation. MRF was proposed to simulate type variables(for example lithofacies) in this work. Firstly, a Gibbs distribution was proposed to characterize reservoir heterogeneity for building 3-D(three-dimensional) MRF. Secondly, maximum likelihood approaches of model parameters on well data and training image were considered. Compared with the simulation results of MC(Markov chain), the MRF can better reflect the spatial distribution characteristics of sand body.

Comprehensive Model Construction and Simulation for Superconducting Electrodynamic Suspension Train

With the advantages of levitation/guidance self-stability,large levitation gap,and high lift-to-drag ratios,superconducting electrodynamic suspension(SC-EDS)train is becoming a viable candidate for the high-speed and ultra-high-speed rail transportation.In order to provide the basis for designing the optimization and control strategy,this paper establishes a comprehensive model for the SC-EDS train,which considers the dynamics of the bogie and car body in all directions.The obtained model reveals the complex coupling and feedback relationships among the variables,which cannot be described by the existing local models of the SC-EDS train.Simulation examples under different parameters and initial conditions are presented and discussed to demonstrate the potential use of the model given in this paper.

潜艇作战嵌入式训练系统研究

嵌入式训练是将仿真系统嵌入到实际装备中,人员操作真实装备进行训练。首先介绍了嵌入式训练的概念和应用情况,然后提出了潜艇作战嵌入式训练系统的三种结构:独立式、集成式和混合式,分析了潜艇作战嵌入式训练系统的工作原理和主要功能。重点研究了嵌入式技术、建模仿真、时空一致、虚拟作战环境生成、计算机生成兵力、评估反馈和航行模拟关键技术,最后提出了潜艇作战嵌入式训练系统的发展趋势。通过加装嵌入式训练系统,可以有效提高潜艇实装的训练效益。

宫腔镜模拟在妇产科技能培训中的应用

宫腔镜是现阶段妇产科医师需掌握的必备手术技能之一,但鉴于宫腔镜检查和手术的特殊性,使其难以通过对患者进行实际操作来提高手术技能。宫腔镜模拟培训是提高医学生及住培医师宫腔镜技能的重要手段,近年来得到国内外学者的重视。文章以国际上最新的研究结果为基础,结合中南大学湘雅三医院宫腔镜培训的经验,对宫腔镜模拟培训的必要性、现阶段宫腔镜模拟培训内容的设置、宫腔镜模拟培训模型的种类及优缺点、宫腔镜模拟培训采用的不同评价体系进行了总结和分析,提示开展相应的宫腔镜模拟培训可在一定程度上提高住培医师对宫腔镜操作的自信心和兴趣,也可以提高其相应的手眼协调能力和基本手术技能,为宫腔镜模拟培训的开展提供一定的参考依据。

翻转课堂和情景模拟教学法在实验室安全培训中的应用

目的 探讨翻转课堂和情景模拟教学法在实验室安全培训中的应用效果。方法 选取兰州大学第一医院医学检验中心2021年6月—2022年6月在岗人员共91名作为培训人员,包括科室人员60名,实习生31名,分为试验组(46名)与对照组(45名)。应用翻转课堂联合情景模拟教学法对试验组培训人员进行实验室安全培训。其中,主要运用翻转课堂模式进行安全理论培训,应用情景模拟教学法进行安全实践操作培训。对照组培训人员用教师讲授法进行理论和操作的培训。培训后进行理论和操作考核。并对所有培训人员进行满意度调查。比较2组理论、实践操作成绩和满意度评分。结果试验组理论成绩为(95.26±3.14)分、实践操作成绩为(89.89±6.06)分及满意度评分为(46.43±3.32)分,均高于对照组的(82.33±5.11)分、(80.56±7.89)分、(38.71±5.53)分,差异有统计学意义(P <0.001)。结论翻转课堂及情景模拟教学法适用于实验室安全培训,并取得了较好的培训效果。

土壤学互融互补混合式智慧教学模式改革成效

土壤学是理论系统性高和应用实践性强的重要专业基础课。探索基于网络信息技术的土壤学线上线下混合式教学的新型模式,对于全面推进新时代一流专业建设及一流专业人才培养至关重要。综合应用文献查阅法、问卷调查法和经验总结法,以优化教学内容和变革教学策略为途径,构建土壤学“互融互补混合式智慧教学模式”。这一新型教学模式包含“思政元素、专业应用、学科前沿、行业发展”的四元融合知识体系、“课前-课中-课后”三环渐进混合式智慧教学方式、“一、二课堂互补,现实虚拟互补”的二维互补实践创新能力培养体系。模式实施以来有力地提升土壤学“一流课程”“思政示范课”建设质效,以及富有“三农”情怀、能“识土-辨土-用土-改土”的新农科复合型高级人才质量,为其他传统专业课改革提供借鉴。

Gallbladder Removal Simulation for Laparoscopic Surgery Training: A Hybrid Modeling Method

Laparoscopic surgery has many advantages, but it is difficult for a surgeon to achieve the necessary surgical skills. Recently, virtual training simulations have been gaining interest because they can provide a safe and efficient learning environment for medical students and novice surgeons. In this paper, we present a hybrid modeling method for simulating gallbladder removal that uses both the boundary element method （BEM） and the finite element method （FEM）. Each modeling method is applied according to the deformable properties of human organs： BEM for the liver and FEM for the gallbladder. Connective tissues between the liver and the gallbladder are also included in the surgical simulation. Deformations in the liver and the gallbladder models are transferred via connective tissue springs using a mass-spring method. Special effects and techniques are developed to achieve realistic simulations, and the software is integrated into a custom-designed haptic interface device. Various computer graphical techniques are also applied in the virtual gallbladder removal laparoscopic surgery training. The detailed techniques and the results of the simulations are described in this paper.

面向空战仿真的智能对手建模研究进展与展望

智能对手建模是空战仿真领域的重要课题,对于加快空战模拟训练的转型升级,提高训练效益、节约训练成本、降低训练风险等方面具有重要意义。总结了近年来国外智能对手建模技术研究进展;论述了智能对手能力需求与关键技术,分别对智能对手对抗空间表示与建模、态势评估与推理、智能对手自主决策与优化、多智能对手行动协同与控制进行分析。对未来空战智能对手建模技术的发展方向进行了总结和展望,以期为相关研究人员提供参考与启发。

基于生成性学习理论的幼儿保育沉浸式虚拟仿真实训设计研究

利用虚拟现实技术进行幼儿保育典型工作环节的虚拟实训,是一项在学前教育教学领域利用虚拟现实技术的模拟性和沉浸性来开展幼儿园生活保育实训的新型实践模式,使学习者能在虚拟的幼儿园环境中,以虚拟实训的方式完成幼儿保育工作的实操实训,目前鲜有相关研究。根据生成性学习理论、沉浸理论,构建基于VR环境的沉浸式虚拟仿真实训生成性学习模型,有利于沉浸式虚拟现实仿真实训在学前教育领域的推广。

基于虚拟现实的森林灭火指挥训练系统研究

森林消防队伍日常训练和考评主要以森林灭火应急预案进行实装演练,针对训练中成本高、环境受限、内容不足等问题,迫切需要采用虚拟现实、人工智能等先进技术实现森林灭火指挥训练与考评系统。本文自主研发了一套基于定制化的Unity3D渲染引擎的虚拟仿真训练教学考评系统。对比国外主流虚拟仿真软件,本系统中场景细节更逼真,能进行实景虚拟仿真训练,更加贴近灭火实战;同时系统具有自主可控性、可扩展性,为用户提供简单编辑方式,支持火环境设计制作等森林消防专业应用逻辑。本文研究结果对于探索建立规范化、信息化森林灭火指挥员训练考评体系具有重要的现实意义。