Theory and practice for assessing structural integrity and dynamical integrity of high-speed trains

Purpose–The safety and reliability of high-speed trains rely on the structural integrity of their components and the dynamic performance of the entire vehicle system.This paper aims to define and substantiate the assessment of the structural integrity and dynamical integrity of high-speed trains in both theory and practice.The key principles and approacheswill be proposed,and their applications to high-speed trains in Chinawill be presented.Design/methodology/approach–First,the structural integrity and dynamical integrity of high-speed trains are defined,and their relationship is introduced.Then,the principles for assessing the structural integrity of structural and dynamical components are presented and practical examples of gearboxes and dampers are provided.Finally,the principles and approaches for assessing the dynamical integrity of highspeed trains are presented and a novel operational assessment method is further presented.Findings–Vehicle system dynamics is the core of the proposed framework that provides the loads and vibrations on train components and the dynamic performance of the entire vehicle system.For assessing the structural integrity of structural components,an open-loop analysis considering both normal and abnormal vehicle conditions is needed.For assessing the structural integrity of dynamical components,a closed-loop analysis involving the influence of wear and degradation on vehicle system dynamics is needed.The analysis of vehicle system dynamics should follow the principles of complete objects,conditions and indices.Numerical,experimental and operational approaches should be combined to achieve effective assessments.Originality/value–The practical applications demonstrate that assessing the structural integrity and dynamical integrity of high-speed trains can support better control of critical defects,better lifespan management of train components and better maintenance decision-making for high-speed trains.

Research Progress of Aerodynamic Multi-Objective Optimization on High-Speed Train Nose Shape

The aerodynamic optimization design of high-speed trains(HSTs)is crucial for energy conservation,environmental preservation,operational safety,and speeding up.This study aims to review the current state and progress of the aerodynamic multi-objective optimization of HSTs.First,the study explores the impact of train nose shape parameters on aerodynamic performance.The parameterization methods involved in the aerodynamic multiobjective optimization ofHSTs are summarized and classified as shape-based and disturbance-based parameterizationmethods.Meanwhile,the advantages and limitations of each parameterizationmethod,aswell as the applicable scope,are briefly discussed.In addition,the NSGA-II algorithm,particle swarm optimization algorithm,standard genetic algorithm,and other commonly used multi-objective optimization algorithms and the improvements in the field of aerodynamic optimization for HSTs are summarized.Second,this study investigates the aerodynamic multi-objective optimization technology for HSTs using the surrogate model,focusing on the Kriging surrogate models,neural network,and support vector regression.Moreover,the construction methods of surrogate models are summarized,and the influence of different sample infill criteria on the efficiency ofmulti-objective optimization is analyzed.Meanwhile,advanced aerodynamic optimization methods in the field of aircraft have been briefly introduced to guide research on the aerodynamic optimization of HSTs.Finally,based on the summary of the research progress of the aerodynamicmulti-objective optimization ofHSTs,future research directions are proposed,such as intelligent recognition technology of characteristic parameters,collaborative optimization of multiple operating environments,and sample infill criterion of the surrogate model.

Upregulation of histone H3 caused by CRYAA may contribute to the development of age-related cataract

Objective:Age-relate cataract(ARC)is a disease of the eyes with no effective drugs to prevent or treat patients.The aim of the present study is to determine whether histone H3,αA-crystallin(CRYAA),β-galactosidase(GLB1),and p53 are involved in the pathogenesis of ARC.Methods:A total of 99 anterior lens capsules(ALCs)of patients with ARC of various nuclear grades,ultraviolet models of ALCs,and two human lens epithelial cell lines(FHL-124 and SRA01/04)were used,and the expression of histone H3,CRYAA,GLB1,and p53 were detected by immunoblotting and reverse transcription and real time-quantitative polymerase chain reaction.The association between CRYAA with histone H3,GLB1,and p53 was assessed in FHL-124 and SRA01/04 cells following CRYAA overexpression.Results:Histone H3 and p53 in ALCs of patients with ARC were up-regulated in a grade-dependent manner,and the expression of CRYAA showed a positive association with histone H3,p53,and GLB1.In UV models of ALCs and human lens epithelial cell lines,the expression levels of histone H3,cell apoptosis factors(Bax/Bcl-2,cleaved caspase-3),and inflammation factors(interleukin-6,tumor necrosis factor-α)were all up-regulated.Furthermore,transfection of CRYAA in FHL-124 cells induced overexpression of histone H3.Conclusion:CRYAA-mediated upregulation of histone H3 may be involved in the pathogenesis of ARC.p53 may also have a role in ARC development,but not via the CRYAA-histone H3 axis.The results of the present study may assist in improving our understanding of the pathogenesis of ARC and in identifying potential targets for treatment.

Fault diagnosis for distillation process based on CNN–DAE

Distillation is the most widely used operation for liquid mixture separation in the chemical industry. It is of great importance to detect and diagnose faults in distillation process. Due to the strong feedback and coupling of processes in a distillation column, it is difficult to use deep auto-encoders(DAEs) alone to achieve good results in detecting and diagnosing faults, in terms of accuracy and efficiency. This paper proposes a hybrid fault-diagnosis model based on convolutional neural networks(CNNs) and DAEs, by integrating the powerful capability of CNN in feature extraction and of DAE in classification. A case study was carried out with the distillation process of depropanization. It is shown that the proposed hybrid model is of good performance compared to other models, in terms of the accuracy of fault detection in such a process. Also, with the increase of structural layers of the CNN–DAE model, the diagnostic accuracy will be improved, with an optimal accuracy of 92.2%.

Influence of pantograph fixing position on aerodynamic characteristics of high-speed trains

To study the influence of the pantograph fixing position on aerodynamic characteristics of high-speed trains, the aerodynamic models of high-speed trains with eight cars were established based on the theory of com- putational fluid dynamics, and eight cases with pantographs fixed on different positions and in different operational orientations were considered. The pantographs were fixed on the front or the rear end of the first middle car or fixed on the front or the rear end of the last middle car. The external flow fields of the high-speed trains were numeri- cally simulated using the software STAR-CCM＋. The results show that the pantograph fixing position has little effect on the aerodynamic drag force of the head car and has a large effect on the aerodynamic drag force of the tail car. The influences of the pantograph fixing position on the aerodynamic lift forces of the head car, tail car and pan- tographs are obvious. Among the eight cases, considering the total aerodynamic drag force of the train and the aerodynamic lift force of the lifted pantograph, when the pantographs are fixed on the rear end of the last middle car and the lifted pantograph is in the knuckle-upstream ori- entation, the aerodynamic performance of the high-speed train is the best.

One compound approach combining factor-analytic model with AMMI and GGE biplot to improve multi-environment trials analysis

To improve multi-environmental trial(MET)analysis,a compound method—which combines factor analytic(FA)model with additive main effect and multiplicative interaction(AMMI)and genotype main effect plus genotype-by-environment interaction(GGE)biplot—was conducted in this study.The diameter at breast height of 36 open-pollinated(OP)families of Pinus taeda at six sites in South China was used as a raw dataset.The best linear unbiased prediction(BLUP)data of all individual trees in each site was obtained by fitting the spatial effects with the FA method from raw data.The raw data and BLUP data were analyzed and compared by using the AMMI and GGE biplot.BLUP results showed that the six sites were heterogeneous and spatial variation could be effectively fitted by spatial analysis with the FA method.AMMI analysis identified that two datasets had highly significant effects on the site,family,and their interactions,while BLUP data had a smaller residual error,but higher variation explaining ability and more credible stability than raw data.GGE biplot results revealed that raw data and BLUP data had different results in mega-environment delineation,test-environment evaluation,and genotype evaluation.In addition,BLUP data results were more reasonable due to the stronger analytical ability of the first two principal components.Our study suggests that the compound method combing the FA method with the AMMI and GGE biplot could improve the analysis result of MET data in Pinus teada as it was more reliable than direct AMMI and GGE biplot analysis on raw data.

路堑高边坡设计安全风险评估研究

山区高速公路路堑高边坡安全风险问题较为突出,目前针对设计阶段公路边坡的风险评估的研究成果较少。为保障路堑高边坡建设安全,基于贵州省对边坡风险管控的迫切需求,结合区域边坡特征构建设计阶段安全风险评估指标体系,提出风险发生概率、风险后果、风险等级评估方法及分级标准,并应用于实际工程。结果表明:风险评估指标体系及方法操作方便,评估结果与实际相符,可为类似工程开展边坡设计风险评估及管理提供参考。

Numerical Study on Aerodynamic Performance of High-Speed Pantograph with Double Strips

Pantograph is a critical component of the high-speed train.It collects power through contact with catenary,which significantly affects the running safety of the train.Pantograph with double collector strips is one common type.The aerodynamic performance of the collector strips may affect the current collection of the pantograph.In this study,the aerodynamic performance of the pantograph with double strips is investigated.The numerical results are consistent with the experimental ones.The error in the aerodynamic drag force of the pantograph between numerical and experimental results is less than 5%.Three different conditions of the strips are studied,including the front strip,the rear strip,and the double strips.Results show that the presence of the front strip will affect the lift force of the rear strip,and reduce the resistance of the rear strip under the opening condition.Meanwhile,the rear strip has few effects on the front strip under the opening operation condition.The law of the resistance for the interaction between two strips under the closing condition is similar to the opening one.

Step-by-Step Numerical Prediction of Aerodynamic Noise Generated by High Speed Trains

In this paper,the unsteady flow around a high-speed train is numerically simulated by detached eddy simulation method(DES),and the far-field noise is predicted using the Ffowcs Williams-Hawkings(FW-H)acoustic model.The reliability of the numerical calculation is verified by wind tunnel experiments.The superposition relationship between the far-field radiated noise of the local aerodynamic noise sources of the high-speed train and the whole noise source is analyzed.Since the aerodynamic noise of high-speed trains is derived from its different components,a stepwise calculation method is proposed to predict the aerodynamic noise of high-speed trains.The results show that the local noise sources of high-speed trains and the whole noise source conform to the principle of sound source energy superposition.Using the head,middle and tail cars of the high-speed train as noise sources,different numerical models are established to obtain the far-field radiated noise of each aerodynamic noise source.The far-field total noise of high-speed trains is predicted using sound source superposition.A step-by-step calculation of each local aerodynamic noise source is used to obtain the superimposed value of the far-field noise.This is consistent with the far-field noise of the whole train model’s aerodynamic noise.The averaged sound pressure level of the far-field longitudinal noise measurement points differs by 1.92 dBA.The step-by-step numerical prediction method of aerodynamic noise of high-speed trains can provide a reference for the numerical prediction of aerodynamic noise generated by long marshalling high-speed trains.

Analysis of steering performance of differential coupling wheelset

In order to improve the curving performance of the conventional wheelset in sharp curves and resolve the steering ability problem of the independently rotating wheel in large radius curves and tangent lines, a differential cou- pling wheelset （DCW） was developed in this work. The DCW was composed of two independently rotating wheels （IRWs） coupled by a clutch-type limited slip differential. The differential contains a static pre-stress clutch, which could lock both sides of IRWs of the DCW to ensure a good steering performance in curves with large radius and tangent track. In contrast, the clutch could unlock the two IRWs of the DCW in a sharp curve to endue it with the characteristic of an IRW, so that the vehicles can go through the tight curve smoothly. To study the dynamic performance of the DCW, a multi-body dynamic model of single bogie with DCWs was established. The self-centering capability, hunting stability, and self-steering performance on a curved track were analyzed and then compared with those of the conventional wheelset and IRW. Finally, the effect of coupling parameters of the DCW on the dynamic performance was investigated.

基于Rockfall数值模拟的危岩体运动规律分析

危岩体发育过程具有渐进性,失稳过程具有突变性和强致灾性,危岩崩塌灾害是山区公路工程建设及运营过程中普遍存在的突发性重大安全隐患,前期预测和分析危岩体落石运动特征可为危岩体治理提供参考。本文以兴义环高某特大桥桥台上方的危岩体为例,通过现场调查研究,分析危岩特征,采用Rockfall数值软件模拟危岩落石运动轨迹、落石终点水平位置,分析落石速度及其能量大小。结果表明:危岩体W5发生崩塌后,有大部分落石到达桥面,且在到达桥面时仍有较大动能和转动速度,会对桥面造成严重撞击和破坏,威胁和影响行车安全。建议对危岩体进行防护或加固,以保障公路建设运营安全。

Numerical simulation and optimization of aerodynamic uplift force of a high-speed pantograph

Aiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent,and their magnitudes do not satisfy the corresponding standard, the aerodynamic uplift forces of pantographs with baffles are numerically investigated, and an optimization method to determine the baffle angle is proposed. First, the error between the aerodynamic resistances of the pantograph obtained by numerical simulation and wind tunnel test is less than 5%, which indicates the accuracy of the numerical simulation method. Second, the original pantograph and pantographs equipped with three different baffles are numerically simulated to obtain the aerodynamic forces and moments of the pantograph components.Three different angles for the baffles are-17°, 0° and 17°.Then the multibody simulation is used to calculate the aerodynamic uplift force of the pantograph, and the optimal range for the baffle angle is determined. Results show that the lift force of the baffle increases with the increment of the angle in the knuckle-downstream condition, whereas the lift force of the baffle decreases with the increment of the angle in the knuckle-upstream condition. According to the results of the aerodynamic uplift force, the optimal angle of the baffle is determined to be 4.75° when the running speed is 350 km/h, and pantograph–catenary contact forces are 128.89 N and 129.15 N under the knuckledownstream and knuckle-upstream operating conditions,respectively, which are almost equal and both meet the requirements of the standard EN50367:2012.

Aerodynamic Design of a Subsonic Evacuated Tube Train System

The so-called Evacuated Tube Train(ETT)is currently being proposed as a high-speed transportation system potentially competitive with airplane transportation.Aerodynamic resistance is one of the most crucial factors for the successful design of an ETT.In the present work,a three-dimensional concept ETT model has been elaborated.The aerodynamic characteristics of the subsonic ETT have been numerically simulated under different conditions.The train’s running speed varies from 600 km/h up to 1200 km/h,and the blockage ratio is in the range between 0.1 and 0.3.As the blocking ratio and running speed increase,the resistance of the head car increases greatly,while the resistance of the middle car changes slightly.The aerodynamic resistance of the tail car is affected by the shock wave emerging in the wake flow.Two different design criteria for the maximum allowed aerodynamic resistance are proposed for aerodynamic parameter matching.With an increase in the blockage ratio and running speed,the atmospheric pressure in the tube should be decreased to achieve a balance.

Aerodynamic performances and vehicle dynamic response of high-speed trains passing each other

Based on the aerodynamics and vehicle dynamics, the aerodynamic performances and vehicle dynamic characteristics of two high-speed trains passing each other on the ground, embankment and bridge are studied. Firstly, a train aerodynamic model and a vehicle dynamic model are established. Through the simulation of the two models, the pressure waves, aerodynamic forces, and vehicle dynamic responses are obtained. Then, the pressure waves and aero- dynamic forces on different foundations are compared. The results show that the variation trends of pressure wave and aerodynamic forces of trains passing each other on different foundations are almost similar. The peak-to-peak differ- ences in pressure wave and aerodynamic force are below 4% and 3% in three cases in open air. Besides, the differences of security indexes, including coefficient of derailment, wheel unloading rate, the wheelset lateral force, and the wheel- rail vertical force, are below 2% among the three cases; the differences of comfort indexes, including the lateral acceleration and the vertical acceleration, are also below 2%. It is concluded that the dynamic performances of trains pass- ing each other are influenced little by different foundations in open air.

Selection of Landscape Tree Species of Tolerant to Sulfur Dioxide Pollution in Subtropical China

Sulfur dioxide (SO2) is a major air pollutant, especially in developing countries. Many trees are seriously impaired by SO2, while other species can mitigate air pollution by absorbing this gas. Planting appropriate tree species near industrial complexes is critical for aesthetic value and pollution mitigation. In this study, six landscape tree species typical of a subtropical area were investigated for their tolerance of SO2: Cinnamomum camphora (L.) J. Presl., Ilex rotunda Thunb., Lysidice rhodostegia Hance, Ceiba insignis (Kunth) P. E. Gibbs & Semir, Cassia surattensis Burm. f., and Michelia chapensis Dandy. We measured net photosynthesis rate, stomatal conductance, leaf sulfur content, relative water content, relative proline content, and other parameters under 1.31 mg·m-3 SO2 fumigation for eight days. The results revealed that the six species differed in their biochemical characteristics under SO2 stress. Based on these data, the most appropriate species for planting in SO2 polluted areas was I. rotunda, because it grew normally under SO2 stress and could absorb SO2.

Various Scoring Systems for Predicting Revascularization of Chronic Coronary Total Occlusion by Percutaneous Coronary Intervention

Successful revascularization of chronic total occlusion (CTO) by percutaneous?coronary intervention (PCI) is associated with reduced major adverse cardiovascular events (MACEs) compared with CTO PCI failure. The developments of new strategies and new devices have improved the success rate of CTO PCI. However, the complexity of CTO lesions, clinical characteristics of patients and operator experience highly determine the successful revascularization. Using search items,?“chronic total occluion”,?“percutaneous coronary intervention”,?“scoring systems”,?“predictablity”.?We searched Pubmed, ScienceDirect, Web of Science, Cochrane Library, and CNKI. We found six clinically used scoring systems from 2011 to 2018. They included J-CTO score, CT-RECTOR score, CL score, PROGRESS CTO score, ORA score, and Ellis score. All parameters of each scoring systems have been systematically reviewed. The patients with higher score have found to have?adecreased?probability of CTO recanalization. Ellis score that mainly focused on ambiguous proximal cap and hybrid approach seems to provide better predictability in deciding procedure strategy.

车轮退化对HXD3型电力机车动力学性能的影响

本文是以HXD3型电力机车为研究对象,根据实测的轮对数据基于随机过程理论揭示不同运行里程下机车轮对退化的演变规律。在此基础上,建立了轮对退化的机车系统动力学模型,分析轮径、轮径差变化对机车动力学性能变化的影响。仿真结果表明:轮径差变化对车辆动力学性能的影响最大,在最大的运行速度120 km/h下,为保障机车运行稳定性,机车安全运行条件下不同里程机车轮径差的工作区间,初始轮径差不能超出7.66 mm,50万里程时轮径差不能超出7.18 mm,100万里程时轮径差不能超出7.21 mm。

Simulation of unsteady aerodynamic loads on high-speed trains in fluctuating crosswinds

To study the unsteady aerodynamic loads of high-speed trains in fluctuating crosswinds, the fluctuating winds of a moving point shifting with high-speed trains are calculated in this paper based on Cooper theory and harmonic superposition method. The computational fluid dynamics method is used to obtain the aerodynamic load coefficients at different mean yaw angles, and the aero- dynamic admittance function is introduced to calculate unsteady aerodynamic loads of high-speed trains in fluctuating winds. Using this method, the standard deviation and maximum value of the aerodynamic force （moment） are simulated. The results show that when the train speed is fixed, the varying mean wind speeds have large impact on the fluctuating value of the wind speeds and aerodynamic loads; in contrast, when the wind speed is fixed, the varying train speeds have little impact on the fluctuating value of the wind speeds or aerodynamic loads. The ratio of standard deviation to 0.SpKU2, or maximum value to 0.5pKU2, can be expressed as the function of mean yaw angle. The peak factors of the side force and roll moment are the same （ - 3.28）, the peak factor of the lift force is - 3.33, and the peak factors of the yaw moment and pitch moment are also the same （- 3.77）.

Experimental investigation of the fluctuations in nonchaotic scattering in microwave billiards

We report on the experimental investigation of the properties of the eigenvalues and wavefunctions and the fluctuation properties of the scattering matrix of closed and open billiards, respectively, of which the classical dynamics undergoes a transition from integrable via almost integrable to fully chaotic. To realize such a system, we chose a billiard with a 60° sector shape of which the classical dynamics is integrable, and introduced circular scatterers of varying number, size,and position. The spectral properties of generic quantum systems of which the classical counterpart is either integrable or chaotic are universal and well understood. If, however, the classical dynamics is pseudo-integrable or almost-integrable,they exhibit a non-universal intermediate statistics, for which analytical results are known only in a few cases, e.g., if it corresponds to semi-Poisson statistics. Since the latter is, above all, clearly distinguishable from those of integrable and chaotic systems, our aim was to design a billiard with these features which indeed is achievable by adding just one scatterer of appropriate size and position to the sector billiard. We demonstrated that, while the spectral properties of almostintegrable billiards are sensitive to the classical dynamics, this is not the case for the distribution of the wavefunction components, which was analyzed in terms of the strength distribution, and the fluctuation properties of the scattering matrix which coincide with those of typical, fully chaotic systems.

Coseismic responses of groundwater levels in the Three Gorges well-network to the Wenchuan M_S8.0 earthquake

We systematically analyze coseismic responses and post-seismic characteristics of groundwater levels in the Three Gorges well-network to the Ms8.0 Wenchuan earthquake on 12 May 2008. The results indicate that these characteristics differ among wells. On the conditions of similar borehole configurations, the differences are associated with geological structural sites of wells, burial types of aquifers monitored, and transmissivities of aquifer systems. We explored coseismic and post-seismic step-rise and step-drop mechanical mechanisms and their implication to earthquake prediction. We validated the inference that the residual step-rise zone is a possible earthquake risk zone based on recent seismic activity on the Xiannüshan fault in the area.