Left Rail Research Articles

Dynamic responses of subgrade under double-line high-speed railway

The majority of high-speed railways around the world is in China and more than 90% of the high-speed railways in China are double-line. At present, studies on the dynamic responses of subgrade under double-line high-speed railways are quite limited due to the complexity of these railways. In this study, a three-dimensional finite element model was developed using ABAQUS software for a double-line ballastless track-subgrade system subject to 8-carriage moving constant loads. The dynamic responses (specifically the vertical stress, displacement, velocity and acceleration) were determined at three points on the subgrade surface (Point A, Point B, and Point C) for trains travelling at different speeds (250, 300, and 360 km/h) and line patterns (unidirectional and bidirectional operations). The vertical stress distributions at selected points on the subgrade surface at these train speeds and line patterns are presented, and the vertical stress distributions along the soil depth of the subgrade at Point A and Point B are discussed. The key findings of this study are as follows. The maximum vertical displacement at the three observation points decreases as the train speed increases whereas the absolute maximum vertical velocity slightly increases as the train speed increases. In bidirectional operation, the maximum vertical stresses occur under the rails on the subgrade surface and the stress distributions are asymmetric. At Point A (point on the subgrade surface underneath the left rail in the left line), the vertical stress decreases along the soil depth and the vertical stress attenuation is more pronounced for bidirectional operation. However, at Point B (point at the centre of the subgrade surface), the vertical stress increases along the soil depth. The vertical stresses at Point A and Point B tend to be close to one another with an increase in soil depth such that the values are nearly coincident in the embankment layer within the range of train speeds investigated in this study.

An adaptive fault diagnosis approach using pipeline implementation for railway inspection

Railway tracks must be periodically inspected. This study proposes a new approach for eliminating two major disadvantages experienced during rail inspection applications performed via computer vision. The first is the blurring effect on images, resulting from physical vibration during movement on the rail lines. This effect significantly reduces the high accuracy rate expected from anomaly inspection algorithms. The second disadvantage is the need to operate in real time. This study presents a new three-stage computer vision method approach that eliminates both disadvantages. First, a three-stage pipeline architecture is implemented and IMU-assisted blur detection is performed on images taken from the left and right rail lines. Next, a convolutional neural network is used for learning. In the third test stage, anomaly detection and classification training are conducted. By performing the implementation with parallel programming on graphic processing units, a highly accurate, cost-effective computer vision rail inspection, based on image processing and capable of operating in real time, is successfully carried out.

How Does a Photocatalytic Antimicrobial Coating Affect Environmental Bioburden in Hospitals?

BACKGROUND The healthcare environment is recognized as a source for healthcare-acquired infection. Because cleaning practices are often erratic and always intermittent, we hypothesize that continuously antimicrobial surfaces offer superior control of surface bioburden. OBJECTIVE To evaluate the impact of a photocatalytic antimicrobial coating at near-patient, high-touch sites in a hospital ward. SETTING The study took place in 2 acute-care wards in a large acute-care hospital. METHODS A titanium dioxide-based photocatalytic coating was sprayed onto 6 surfaces in a 4-bed bay in a ward and compared under normal illumination against the same surfaces in an untreated ward: right and left bed rails, bed control, bedside locker, overbed table, and bed footboard. Using standardized methods, the overall microbial burden and presence of an indicator pathogen (Staphylococcus aureus) were assessed biweekly for 12 weeks. RESULTS Treated surfaces demonstrated significantly lower microbial burden than control sites, and the difference increased between treated and untreated surfaces during the study. Hygiene failures (>2.5 colony-forming units [CFU]/cm2) increased 2.6% per day for control surfaces (odds ratio [OR], 1.026; 95% confidence interval [CI], 1.009-1.043; P=.003) but declined 2.5% per day for treated surfaces (OR, 0.95; 95% CI, 0.925-0.977; P<.001). We detected no significant difference between coated and control surfaces regarding S. aureus contamination. CONCLUSION Photocatalytic coatings reduced the bioburden of high-risk surfaces in the healthcare environment. Treated surfaces became steadily cleaner, while untreated surfaces accumulated bioburden. This evaluation encourages a larger-scale investigation to ascertain whether the observed environmental amelioration has an effect on healthcare-acquired infection. Infect Control Hosp Epidemiol 2018;39:398-404.

MATHEMATICAL MODEL OF DPKR-2 DYZEL TRAIN CAR

Purpose. In order to study the dynamic phenomena arising when rolling stock moves along a rail track both in the straight and curved track sections, the article is aimed to construct a mathematical model of DPKr-2 diesel train car. It will be constructed on the basis of mechanical model of this car of Kryukiv Railway Car Building Works. Methodology. To construct a mathematical model a system of 38 differential equations of the diesel train movement is formed. When it is used a pneumatic spring in the core stage of spring suspension, its equivalent mechanical mo-del is presented as Kelvin-Voigt knot. It includes a parallel elastic element and an element of viscous friction. Rail track flexibility is taken into account by elastic and dissipative elements. During simulation it was assumed that the wheel pair and the track weight interacting with it were moving intact. Geometric inequalities of the left and right rails were accepted as disturbances when studying the forced vertical and horizontal oscillations. Findings. On the basis of the adopted mechanical model of the diesel train car we constructed the mathematical model consisting of 38 differential equations of motion . Originality. For the first time, for the DPKr-2 diesel train car we developed its spatial mathematical model taking into account the features of the interaction of individual elements of its construction and the possibilities of the rail track depression. When constructing the mathematical model, it was proposed to take into account the flexibility of the rail track by elastic and dissipative elements. Originality. The mathematical model of the diesel train car will be used for studying the dynamic phenomena and determining the dynamic loads of structural elements during operation. The study of these phenomena is necessary for optimal choice of the scheme and parameters of rolling stock equipment, in particular antivibration devices (spring suspension, horizontal, longitudinal and transverse joints of wheel pairs with the bogie frame, bogie with the body), as well as for reduction of dynamic forces acting on the elements of rolling stock construction and rail track.

Application of Geocell Track Substructure Support System to Correct Surface Degradation Problems Under High-Speed Passenger Railroad Operations

Ballast fouling and associated degradation of track geometry is a serious problem for railway systems in general and high-speed passenger rail systems in particular. This paper presents the results of a field test on Amtrak’s Northeast Corridor where a long-term problem area existed near Oakington Road, Havre de Grace, Maryland, near MP 63.7 between Philadelphia and Washington DC. This test looked at the application of a new generation of three-dimensional cellular confinement systems (geocells) in reducing the rate of track geometry degradation, particularly in poor subgrade and ballast locations which require frequent, expensive, track surface maintenance. The field test compared two distinct sets of rebuilt track conditions, to include zones with and without a layer of geocell material. Both zones were rebuilt with improved drainage and a good, well-defined track structure and substructure (to include a well-defined depth of clean ballast). The test measurements included pre-maintenance and post-maintenance track geometry measurements together with comparative subgrade pressure measurements inside and outside the geocell cell zones. The pressure cell measurements, which looked at subgrade pressure under left and right rails in both the geocell zone and the control (non-geocell) zones, included measurements under both Acela high-speed trains and lower speed regional trains. In all cases, the subgrade pressures in the geocell zone were approximately half of those for the cells in the control zone (no geocell). Track geometry measurements were made using Amtrak’s track geometry vehicle which measures key track geometry parameters at 1-ft intervals along the track. There were several well-defined locations in the overall test zone that experienced significant track geometry degradation; these were all corrected during reconstruction. In the zones with no geocell material, these geometry variations reappeared within 6 to 7 months with the same if not greater amplitudes. By contract, in the geocell zone, the “after” geometry variations were significantly smaller than the pre-reconstruction geometry variations. Furthermore, the rate of geometry degradation was signficantly less for the geocell zones compared to the pre-geocell time periods for the exact same track. This indicated the effectiveness of the geocell material in reducing the rate of track geometry degradation and extending the surfacing maintenance cycles. Analysis of the rate of degradation showed that the effect of installing the geocell material was to significantly reduce the rate of degradation (and thus increase the surfacing cycle) by a factor of 6.7 times the pre-geocell installation surfacing cycle.

Vibration based diagnosis of wheel defects of metro train sets using one period analysis on the wayside

This research examines two different methods; Wavelet Packet Energy (WPE) and Time-domain Features (TDF) which are effective in faulty signal feature extraction of metro wheels in wayside level using vibration sensors. Signals of each wheelset passing of a trainset with both healthy and faulty wheels are recorded by the vibration sensors which are mounted on both left and right rails and a novel one-period sampling is performed at 51.2 kHz sample rate. Retrieved signal samples are used in the construction of a database which is consistent of healthy and faulty cases. Since the database has insufficient number of faulty samples, the database is balanced by a method so called Adaptive Synthetic Sampling (ADASYN) so that each class has the same number of observations. Two state-of art classifiers; Support Vector Machines (SVM) and Fisher Linear Discriminant Analysis (FLDA) are employed by utilizing 16-fold cross validation to solve the two-class problem. Referring to the results, SVM-I-TDF outperforms by classifying all samples with a success rate of 100 % and other methods have also promising results. Proposed methods may be used in the condition monitoring of metro wheelsets effectively by means of not only performance but also cost-efficiency.

Investigation of rail irregularity effects on wheel/rail dynamic force in slab track: Comparison of two and three dimensional models

Rail irregularity is one of the most significant load amplification factors in railway track systems. In this paper, the capability and effectiveness of the two main railway slab tracks modeling techniques in prediction of the influences of rail irregularities on the Wheel/Rail Dynamic Force (WRDF) were investigated. For this purpose, two 2D and 3D numerical models of vehicle/discontinuous slab track interaction were developed. The validation of the numerical models was made by comparing the results of the models with those obtained from comprehensive field tests carried out in this research. The effects of the harmonic and non-harmonic rail irregularities on the WRDF obtained from 3D and 2D models were investigated. The results indicate that the difference between WRDF obtained from 2D and 3D models is negligible when the irregularities on the right and left rails are the same. However, as the difference between irregularities of the right and left rails increases, the results obtained from 2D and 3D models are considerably different. The results indicate that 2D models have limitations in prediction of WRDF; that is, a 3D modeling technique is required to predict WRDF when there is uneven or non-harmonic irregularity with large amplitudes. The size and extent of the influences of rail irregularities on the wheel/rail forces were discussed leading to provide a better understanding of the rail-wheel contact behavior and the required techniques for predicting WRDF.

A Study on the Experimental Analysis of Noise from Vehicle Power Seat Slide Rail

In this study was conducted with focus on the change in vibration characteristics in the rail to analyze the noise produced in the rail upon operation of slide mechanism in power seat for vehicles. Preferentially, the motor rpm was simultaneously measured about operating noise, vibration as operating into direction of forward and backward with the slide mechanism. And, modal test was conducted according to operation position of the seat rail, through which overall analysis was conducted for the effects of vibration characteristics of the rail on operating to noise. According to the results, it could be seen that resonance occurred between the 2nd natural frequency generated on the left upper rail and the 3rd order of motor rotation to affect the operating noise.

Influence of uneven rail irregularities on the dynamic response of the railway track using a three-dimensional model of the vehicle–track system

A mathematical model of the vehicle–track interaction is developed to investigate the coupled behaviour of vehicle–track system, in the presence of uneven irregularities at left/right rails. The railway vehicle is simplified as a 3D multi-rigid-body model, and the track is treated as the two parallel beams on a layered discrete support system. Besides the car-body, the bogies and the wheel sets, the sleepers are assumed to have roll degree of freedom, in order to simulate the in-plane rotation of the components. The wheel–rail interface is treated using a nonlinear Hertzian contact model, coupling the mathematical equations of the vehicle–track systems. The dynamic interaction of the entire system is numerically studied in time domain, employing Newmark's integration method. The track irregularity spectra of both the left/right rails are taken into account, as the inputs of dynamic excitations. The dynamic responses of the track system induced by such irregularities are obtained, particularly in terms of the vertical (bounce) and roll displacements. The numerical model of the present research is validated using several benchmark models reported in the literature, for both the smooth and unsmooth track conditions. Four sample profiles of the measured rail irregularities are considered as the case studies of excitation sources, examining their influences on the dynamic behaviour of the coupled system. The results of numerical simulations demonstrate that the motion of track system is significantly influenced by the presence of uneven irregularities in left/right rails. Dynamic response of the sleepers in the roll direction becomes more sensitive to the rail irregularities, as the unevenness severity of the parallel profiles (quantitative difference between left and right rail spectra) is increased. The severe geometric deformation of the track in the bounce–pitch–roll directions is mainly related to such profile unevenness (cross-level) in left/right rails.

2C22 Development of the secondary suspension for the improvement of the wheel load variation (Part2)(Safety-Vehicle)

Improving running safety in sharp curves, especially in transition curve, reducing wheel load variation is very important. When railway vehicle runs in transition curve section, superelevation gradually reduces continuously and the plane consisted of right and left rail is twisted. This track twist produce diagonal differential pressures of secondary suspensions in the car which makes unbalance of wheel load in the car. So we developed newly system "connecting front and rear air springs" to reduce wheel load variation. Connecting front and rear air springs has an effect of cancellation of diagonal differential pressures, which can be realized by additional air pipings and differential pressure valves. We installed this system in Tokyo Metro Chiyoda line train, and carried out test run to evaluate the effect of this system. The test data show wheel load variation rate of proposed system was improved compared to conventional system. And the diagonal differential pressure (equal to car body twist) was significantly improved with this system.The test results show that wheel load variation rate is improved approximately from 20% to 30%, as a result, derailment coefficient data was improved approximately from 15% to 25% for each curves in the test.

Calculated disturbances for evaluation of dynamical properties of freight cars

Purpose. To form realizations of the calculated disturbances for studying the dynamic properties of railway vehicles. Methodology. Records of the track-test car for one of the typical track sections of the Pridneprovsk railroad are the basic data for building the disturbance components. To derive the true geometric parameters of the railway gauge the records of the track-test car using a double-point metering circuit are transformed considering the transfer function of the measuring system. A model of the calculated disturbances is presented as the four components: a symmetric vertical irregularity determined as a semi-sum of vertical irregularities of the right and left rails; an oblique-symmetric vertical irregularity of the track determined as a semi-difference of vertical irregularities of the right and left rails; horizontal irregularities of the right and left rails. Acceptability criterion of the constructed disturbances is a relationship between the values of the dynamical properties factors of cars and the corresponding experimental data. Findings. The three techniques for the calculated disturbances forming are proposed. The first technique uses records of the track-test car for the track with a sufficiently high amount for given track conditions as components of the calculated disturbances. In so doing symmetrical vertical components of disturbances resulting from records of settling are corrected with the mass and stiffness parameters of the car under consideration. The second technique uses building and applying the theoretical realizations of irregularities corresponding to a real track according to a spectral analysis. The third technique ensures a polyharmonic model of disturbances, the parameters of which are the values of the basic frequencies and amplitudes that are typical for irregularities of a railway track. A possibility of practical applying of the constructed models of disturbances are presented using an example for defining the standardized factors of the dynamical properties of empty and loaded open cars. Comparison of the calculated factors and experimental data demonstrated its assurance. Originality. The three models of the calculated disturbances that can be used for calculating estimation of the maximal values of the standardized dynamical factors of freight vehicles are proposed. Practical value. The research results ensure an acceptable predicted evaluation of the dynamical properties factors for the designed or refitted vehicles of railway rolling stock, refinement of the values of the certain system parameters at the stage of prototypes, reduction of the expenses for performance trials, etc.

Prediction of railway induced ground vibration through multibody and finite element modelling

Abstract. The multibody approach is now recognized as a reliable and mature computer aided engineering tool. Namely, it is commonly used in industry for the design of road or railway vehicles. The paper presents a framework developed for predicting the vibrations induced by railway transportation. Firstly, the vehicle/track subsystem is simulated, on the basis of the home-made C++ library EasyDyn, by mixing the multibody model of the vehicle and the finite element model of the track, coupled to each other through the wheel/rail contact forces. Only the motion in the vertical plane is considered, assuming a total symmetry between left and right rails. This first step produces the time history of the forces exerted by the ballast on the foundation, which are then applied to a full 3-D FEM model of the soil, defined under the commercial software ABAQUS. The paper points out the contribution of the pitch motion of the bogies and carbodies which were neglected in previous publications, as well as the interest of the so-called coupled-lumped mass model (CLM) to represent the influence of the foundation in the track model. The potentialities of the model are illustrated on the example of the Thalys high-speed train, riding at 300 km h−1 on the Belgian site of Mévergnies.

레일 경좌 변화에 따른 곡선부 통과열차의 주행안전성 해석

So far today, there is a speed limit by the radius of curve based on operation regulation in domestic railway, however a study for the maximum running speed at the curved section without any derailment would be necessary. The two major factors related to the running safety of railway vehicle are classified as the railway vehicle condition and the track condition. In terms of the rail inclination among many other factors, the determination of rail inclination within the possible limit is necessary for the geometrical structure of the optimum track. The disregard of the geometrical parameter related to the rail inclination may cause a serious problem to the running safety of railway vehicle. This study is focusing on the analyzing of running safety regard to the change of rail inclination among the many other parameters to improve derailment safety, so that there is an affection analysis of the running safety regard to the change of rail inclination in the ideal and geometric track condition. Also There is an affection analysis of the running safety regard to the simultaneous change of rail inclination and the running speed at the curved section. According to analysis results of running safety, In case that the left and right rail inclination are 1/40, the running safety of this condition defined than other conditions. Also, the rail inclination of conventional lines is 1/40, Therefore, the railway vehicle passing through curve is safe when the railway vehicle runs in conventional lines.

Method of Modeling the Excitation Spectrum of Train Based on Track Irregularity

A new technique is present in this paper that transforms the railway track irregularity power spectral density of left and right rails into the excitation power spectral density of wheelset of train, compared with the railway track irregularity spectrums of left and right rails which are not the direct inputs of simulation dynamic model of trail. A parameter model is chosen as the model of excitation spectrum and parameters fitting result shows that this model is suitable for the excitation spectrums of traversing, floating and head shaking, and the method present in this paper is effective.

Accurate Representation of the Rail Geometry for Multibody System Applications

The objective of this study is to examine the geometric description of the spiral sections of railway track systems, in order to correctly define the relationship between the geometry of the right and left rails. The geometry of the space curves that define the rails are expressed in terms of the geometry of the space curve that defines the track center curve. Industry inputs such as the horizontal curvature, grade, and superelevation are used to define the track centerline space curve in terms of Euler angles. The analysis presented in this study shows that, in the general case of a spiral, the profile frames of the right and left rails that have zero yaw angles with respect to the track frame have different orientations. As a consequence, the longitudinal tangential creep forces acting on the right and left wheels, in the case of zero yaw angle, are not in the same direction. Nonetheless, the orientation difference between the profile frames of the right and left rails can be defined in terms of a single pitch angle. In the case of small bank angle that defines the superelevation of the track, one can show that this angle directly contributes to the track elevation. The results obtained in this study also show that the right and left rail longitudinal tangents can be parallel only in the case of a constant horizontal curvature. Since the spiral is used to connect track segments with different curvatures, the horizontal curvature cannot be assumed constant, and as a consequence, the right and left rail longitudinal tangents cannot be considered parallel in the spiral region. Numerical examples that demonstrate the effect of the errors that result from the assumption that the right and left rails in the spiral sections have the same geometry are presented. The numerical results obtained show that these errors can have a significant effect on the quality of the predicted creep contact forces.

Design evaluation of a French refrigerator drawer system subjected to repeated food storage loads

Based on field data and a tailored set of accelerated life tests, the drawer system of food storage in a French refrigerator was redesigned. Using a force balance analysis, the simple mechanical loads of the drawer system were evaluated. The failure modes and mechanisms found experimentally were similar to those of the failed samples in the field. Failure analysis, accelerated life tests and corrective action plans were used to identify the key control parameters and level for the mechanical drawer system. The missing controllable design parameters of the drawer system in the design phase included no corner rounding and rib thickness in the intersection areas between the box and its cover, the right, center support and left rail system. After a tailored series of accelerated life tests with corrective action plans, the B 1 life of the new draw system is now guaranteed to be over 10 years with a yearly failure rate of 0.1%.

Constraint equations between the wheelset and rails on straight railway track

The rolling angle and the vertical displacement of the centre of gravity of the wheelset are not independent degrees of freedom while the wheelset runs on railway track. On straight track, the effects of the lateral displacement of the wheelset, of the lateral and vertical displacements of the neutral axis of the left and right rails, of roll around the centre roll of the left and right rails, of the longitudinal profile and lateral alignment irregularities of the left and right rails, and of the conicity of the left and right wheel treads on the rolling angle and the vertical displacement of the centre of gravity of the wheelset are considered in this paper. A generalized spatial rail beam element is presented. The finite element forms of the constraint equations for rolling angle, rolling angular velocity, rolling angular acceleration, vertical displacement, vertical velocity and vertical acceleration of the centre of gravity of the wheelset are expressed by the dependent factors mentioned above. These equations can be useful in three-dimensional vehicle/track interaction modelling.

SPRINT AND BALANCE ABILITY AFTER 30 DAYS OF BEDREST WITH VERSUS WITHOUT SUPINE LBNP EXERCISE

Introduction: We hypothesized supine treadmill exercise in lower body negative pressure (LBNP) would decrease losses of sprint and balance ability in subjects exposed to prolonged microgravity, simulated by 30 days of bedrest in 6 degree head down tilt. Methods: Six pairs of male identical twins (n = 12) were tested PRE and POST bedrest for one foot rail balance eyes closed (EC) (up to 30 sec), sprint time (30.5m) and rail walk balance eyes open (EO) (4.9m beam). Each twin was randomly assigned to: 1) an experimental group that ran on a vertically oriented treadmill 40 minutes, 6 days per week in LBNP (EXP) or 2) a control group that did not (CON). Rail balance performance was determined by averaging percent distance traveled divided by total time. Results: EXP performed better (but not significantly) than CON in POST left and right EC rail balance (EXP left: 17.5 (4.82)s; right: 13.8 (4.80)s, CON left: 8.6 (4.24)s; right: 10.0 (4.73)s (mean (SE))) and in POST sprint (EXP 5.2 (0.15)s, CON 5.8 (0.16)s). Significant differences (P < 0.05) existed between PRE and POST performances for the subsequent reported comparisons. Left and right foot balance times EC were longer PRE than POST for both CON (left: 26.0 (4.02)s; right: 21.56 (5.34)s vs. left: 8.6 (4.24)s; right: 10.0 (4.73)s) and EXP (left: 24.4 (3.34)s; right: 16.8 (3.14)s vs. left: 17.5 (4.82)s; right: 13.8 (4.80)s). PRE sprint times were faster than POST times for both CON (4.8 (0.20)s vs. 5.8 (0.16)s) and EXP (4.7 (0.35)s vs. 5.2 (0.15)s). Rail walk EO was better PRE than POST for both CON (10.7 (1.80) % s-1 vs. 8.3 (1.48) % s-1) and EXP (10.2 (1.47) % s-1 vs. 7.6 (1.97) % s-1). Trends in results suggest exercise in LBNP may reduce loss of sprint and balance ability. This research was supported by National Aeronautics and Space Administration grant #199–26–12–34.

Random Field Modeling of Railway Track Irregularities

Track irregularity is considerably important in track-vehicle studies. Recorded data of these irregularities form a basis to develop track standards. This also helps specify track inputs to the vehicles. In this paper random field models for vertical irregularity data obtained from Indian railways has been presented. It is shown that irregularity in the vertical profile can be modeled as stationary Gaussian random field, which can be defined in terms of the power spectral density (PSD) function. Such a model can predict the values of peak amplitudes in a given track length. Further, the absolute vertical profile of the left and right rails belong to the isotropic random field. The implication of this in describing the input matrix of multiaxle vehicles is discussed.

Electronic recording of pressure exerted by cows against structures in free-stall housing

Pressure exerted by cows against the feeding rail and side rails, neck rail and brisket board of cubicles was recorded by means of pressure transducers. Video surveillance was used to examine the nature of the body contact.Pressure during feeding was recorded during a normal and a contrived situation at the feeding table, and during feeding from a manger elevated 16–18 cm above floor level. Forty-three percent of recordings were above 50 kg during the contrived situation and 8% when feeding from the standard manger.In the cubicle, side rails were leant against most often. The resting cow pressed more frequently on the left side rail than on the right one, viz. 28 vs. 10% of recordings over 50 kg. Occasionally, cows bumped the brisket board with their front legs. This could result in contusions to the knees. The neck rail was only occasionally touched by the cows.