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In view of the abnormal wear of the vibration damping track with small radius curve on the subway, the vibration and noise problems associated with it have been widely concerned by society. The dynamic model of vehicle-track system including elastic damping track is established by using simulation software. The influence of structural parameters of steel spring floating slab track (SSFST) with small radius curve on the mode and vibration frequency, as well as the resonance characteristics of elastic track structure are analyzed. The results show the following: (1) Increasing the length of floating slab can effectively reduce natural frequency, while the range of frequency variation caused by the thickness of floating slab is relatively small. The length and thickness of floating slab can be properly adjusted to avoid the track resonance. (2) It is more integrated for the rail and floating slab through increasing the vertical stiffness of fastener, which increases the vibration frequency of the track structure. There is little effect on the vibration characteristics of SSFST for changing the installation spacing of steel springs. (3) It is more obvious for resonance to occur between the inner rail and floating slab at 116 Hz, 130 Hz and 161 Hz, and the track vibration mode shows multi-step reverse vibration on both sides and overall vertical bending vibration. (4) Due to the unbalance load caused by curve superelevation, the inner wheel weight plays the restraining role, which makes the inner rail and floating slab have various forms of bending deformation in a certain frequency range, increasing the complexity of the bending deformation of the track structure. [ABSTRACT FROM AUTHOR]

The estimation of maximum storm surges along a coast is indispensable for emergency action planning, design, and adaptation of coastal infrastructure. The existing studies on the Bay of Bengal coast have used synthetic tracks with constant track parameters such as the maximum wind speed, radius of maximum wind, and central pressure to estimate the probable maximum storm surges. However, the analysis of the best tracks from the Joint Typhoon Warning Center during 1978–2019 shows that the track parameters vary from origin to landfall locations. The reported studies along the Bay of Bengal have failed to capture such variations and overestimated probable maximum storm surges due to constant track parameters. Therefore, this study proposes a methodology for estimating wind speed of various return periods and associated track parameters that vary along a synthetic track. The wind speed of different return periods is computed at each eye location using the probabilistic approach. Thus, the calculated wind speeds vary from origin to landfall locations, and such a pattern of wind speed variation is observed to be similar to the historical cyclones. The radius of maximum wind and central pressure is calculated using the regression equations derived from historical tracks. The accuracy of the proposed methodology is investigated by simulating the cyclones Thane and Vardah that occurred along the Tamil Nadu coast. The results suggest that the varying track parameters using the proposed methodology produce realistic surge values similar to parameters from best track data, and it overcomes the overestimation of surge heights. The proposed methodology is further utilized to analyse the maximum surge scenarios along the Tamil Nadu coast resulting from various track shifts and angles of attack. The proposed methodology is expected to improve the estimation of storm surges in other basins. [ABSTRACT FROM AUTHOR]

The objective of this paper is to describe a model for the simulation of the lateral dynamics of a vehicle, specifically buses, under variable trajectory conditions, such as camber and radius of curvature; in addition, a variable speed is added as a simulation parameter. The objective of this study is the prevention of vehicle rollover and sideslip. An 8 degrees of freedom model was developed, considering a front and a rear section of the bus with its respective suspension system, and both sections have been connected by a torsion spring that emulates the torsional stiffness of the vehicle chassis. A Panhard bar is also added at the rear as an additional element to the suspension and the behavior of the bus when it is added is analyzed. This model also allows the evaluation of the force on each suspension component, which allows for future controllability of the active suspension components. The results show the dynamic behavior of the vehicle, and some indicators are introduced to show the possible sideslip or rollover. As a conclusion, the influence of the road parameters on the dynamic behavior of the bus and the effect of the Panhard bar on the dynamic behavior of the bus can be pointed out. [ABSTRACT FROM AUTHOR]

Carbody hunting stability has attracted more and more attention due to its great influence on the dynamic performance of a railway vehicle. To fully understand the correlation between the wheel–rail contact relationship and the carbody hunting stability of an electric locomotive, the wheel–rail contact geometry analysis and the multi-body dynamics simulation are carried out in this work. The focus is on the influences of track parameters (including rail profile, rail cant and track gauge) on wheel–rail contact relationships and carbody hunting stability. A group of rail profiles are obtained by interpolating between the standard CHN60 profile and the worn rail profiles. The nominal equivalent conicity, the effective equivalent conicity and the wheel–rail contact bandwidth for a wheelset lateral displacement of ±6 mm are used to evaluate the wheel–rail contact relationship, while the lateral continuous comfort index is used to evaluate the carbody hunting stability. The simulation results show that keeping the rail cant at about 1/40 and reducing the track gauge and the wear depth at the gauge corner of rail can improve the carbody hunting stability of the electric locomotive. Furthermore, the effective equivalent conicity is a good choice to establish the relationship between the wheel–rail contact geometry and the carbody hunting stability. [ABSTRACT FROM AUTHOR]

The objective of this paper is to describe a model for the simulation of the lateral dynamics of a vehicle, specifically buses, under variable trajectory conditions, such as camber and radius of curvature; in addition, a variable speed is added as a simulation parameter. The objective of this study is the prevention of vehicle rollover and sideslip. An 8 degrees of freedom model was developed, considering a front and a rear section of the bus with its respective suspension system, and both sections have been connected by a torsion spring that emulates the torsional stiffness of the vehicle chassis. A Panhard bar is also added at the rear as an additional element to the suspension and the behavior of the bus when it is added is analyzed. This model also allows the evaluation of the force on each suspension component, which allows for future controllability of the active suspension components. The results show the dynamic behavior of the vehicle, and some indicators are introduced to show the possible sideslip or rollover. As a conclusion, the influence of the road parameters on the dynamic behavior of the bus and the effect of the Panhard bar on the dynamic behavior of the bus can be pointed out.

To investigate the effects of a trapezoidal sleeper track (TST) on the vibration and noise of rail transit viaducts, the wheel–rail interaction model was first built according to the vehicle–track coupling dynamics theory. Subsequently, the vibration responses of the viaduct were analyzed using the beam–slab finite element method, and its radiated noise was calculated using the acoustic boundary element method. The modeling method was verified based on the test data of a 3 × 40 m continuous rigid frame bridge. Taking the Jialing River Bridge of Chongqing Rail Transit Line 9 as the background, the control effects of the TST on the vibration and noise of the viaduct and the effective laws of different track parameters on the bridge noise were analyzed. Results show that the simulated and measured values are in good agreement; for example, the modeling methods are reliable; the radiated noise of the viaduct is influenced by the vibration responses under the action of train load, which are jointly determined by dynamic wheel–rail force (external excitation) and displacement admittance (self-vibration characteristics); compared with embedded sleeper track (EST), the TST can reduce the overall vibration acceleration level and sound pressure level of the box girder web plate by 13.9 dB and 7.8 dB, respectively; the stiffness of the damping path is the primary factor influencing the noise of the elevated box girder, followed by the sleeper thickness and the fastener stiffness; taking the bottom plate as an example, the stiffness of the damping pad is reduced by 1 and the overall sound pressure level can be reduced by approximately 3 dB; the sleeper thickness is increased by 1, and the overall sound pressure level can be reduced by 1–2 dB; and the fastener stiffness is reduced by 1, and the noise reduction is within 1 dB. [ABSTRACT FROM AUTHOR]

Tracked mining vehicles (TMVs) are key equipment in deep-sea mining systems and can easily slip when walking on soft sediments on the seabed. Thus, it is important to investigate the effect of track parameters and grounding-specific pressure on the shear interaction between mining vehicles and sediment. The sediment was simulated using a mixture of bentonite and water, and a shear test of the track with a single grouser and sediment was conducted. A numerical model of the track–sediment shear test was established, and the shear strength and failure mode of the sediment soil under the track action were examined. The results demonstrate that the peak shear strength of the track–sediment interface increases with an increase in the grounding-specific pressure, gradually increases with an increase in grouser height, and tends to stabilize at a given level of grouser height. Owing to the presence of the grouser, the deep-sea sediment transitions from the elastic state to the plastic state faster than the typical clay during the shear test. The variation law of peak shear strength at the track-sediment interface with the height of track grouser under different grounding-specific pressures was analyzed, and a modified shear stress-displacement relationship model was proposed. Wedge failure is the predominant method of failure for a single-grouser shear sediment soil at various heights. The primary factor affecting the horizontal disturbance range is the grouser height, and the range increases as the grouser height increases; the primary element affecting the vertical disturbance range is the grounding-specific pressure, and the range increases as the grounding-specific pressure increases. The relationship of the grouser height and cohesiveness with the interfacial shear strength was examined and a new shear stress–displacement relationship model that can accurately capture the shear mechanical behavior between the track and sediment under various grouser heights was proposed. In conclusion, the study findings could serve as a guide for the engineering design of a TMV walking system. • Explored the characteristics of the shear stress-displacement curves, and analyzed the effects of the grouser height and the grounding specific pressure on the peak shear strength of the interface. • Proposed a shear stress-displacement relationship model considering the grouser parameters. • Analyzed the failure process and final failure mode of sediment from the mesoscopic perspective. [ABSTRACT FROM AUTHOR]

In this study, a numerical procedure is developed to predict the wear of turnout rails, and the effect of track parameters is investigated. The procedure includes simulation of the dynamic interaction between the train and the turnout, the rolling contact analysis, and the wear model. The dynamic interaction is simulated with the validated commercial software Simpack that uses a space-dependent model of a railway turnout. To reproduce the actual operating conditions of a railway turnout, stochastic variations in the input parameters are considered in the simulation of the dynamic interaction. The rolling contact is analyzed with the semi-Hertzian method and improved FASTSIM algorithm, which enable the contact model to deal with situations of multipoint contact and nonelliptic contact. Based on the Archard’s wear law, the wear model requires the calculation of normal/tangential stresses and a relative slide on the contact patches. The numerical procedure is performed for the selected sections of the vehicle, which runs through the railway turnout in the diverging route. By using the numerical procedure, the effect of track parameters (track gage, rail inclination, and friction coefficient) on the wear of turnout rails is analyzed. The results show that the wear of the front wheelset is more serious than the wear of the rear wheelset for a single vehicle. The degree of wear of switch rails is more severe than that of the stock rails and the difference is more obvious for the front wheelset of the switch rails. The wear of switch rails is mainly concentrated on the rail gage corner, while the wear of stock rails is mainly concentrated on the rail crown. For the analysed CN60-1100-1:18 turnout and the high-speed vehicle CRH2 in China, the rail wear rate could be slowed down by increasing the track gage and decreasing the rail inclination. Alternatively, the rail wear rate could be slowed by decreasing the friction coefficient; however, the variation of wear depth is quite small for friction coefficients that are larger than 0.3. [ABSTRACT FROM AUTHOR]

In response to the global demand for commercial mining of deep-sea manganese nodules, the four-tracked mining vehicle (FTMV) with excellent tractive and travelling performance is crucial for constructing the entire commercial system. In order to better evaluate the tractive and travelling performance of the FTMV, the dynamic sinkage phenomenon concerning soft seabed and front-rear track effect are proposed. Meanwhile, the pressure-sinkage and traction force-slip rate mathematical models are established based on terramechanics theory. The quantitative calculation was carried out based on the model and found that the grouser's parameters affect the sinkage depth of the FTMV. In the range of 10 ~ 20 cm, the height of the rectangular grouser increases by 1 cm, which will lead to a 0.15 cm of sinkage depth decreased. When the ratio of rectangular grouser thickness to track shoe length is between 0.1 and 0.3, every 1% increase in this ratio will decrease a 0.13 cm of sinkage depth. The maximum traction force obtained by the FTMV from the soft seabed sediment was 54.5 kN, which occurred when the slip rate of the track was 16%. Moreover, due to the front-rear track effect, the traction force of the front and rear tracks showed a significant difference, the front track contributed 32.4 kN, and the rear track contributed 22.1 kN when the traction force reached the peak. Furthermore, the optimization directions for track parameters were suggested according to the relationship surface of the track dimensional parameters-slip-traction. It was found that each track was 4.2 ~ 6 m long, with a length-width ratio of 3.2, which was conducive to the reduction of track slip and got relatively much traction force from soft seabed sediment. The simulation results confirm dynamic sinkage and front-rear track effect and verify the accuracy of the new traction force-slip rate model, providing a valuable reference for the development of commercial deep-sea mining vehicles. • The dynamic sinkage phenomenon and the front-rear track effects of the four-tracked vehicle are proposed. • The track traction force-slip rate model of the four-tracked seabed mining vehicle was derived. • Quantitative calculations and three groups of computer simulations were conducted to verify the accuracy of the new traction force-slip rate model. [ABSTRACT FROM AUTHOR]

The aim of this research is study of tracks growth experimentally and theoretically in cellulose nitrate LR-115 detector .The detector of 12jam thickness is irradiated normally by alpha particles with incident energies from 1 to 5MeV and incident angle 90°,by using 24lAm source , The etching of the detector Pieces was implemented by using chemical etchant NaOH with concentration 10% and temperature (60±1°C) ,A computer program ,(TRACK_TEST) also used for calculating track parameters as tracks depth and plotting track-wall profiles and contours of the track opening .The results showed that a maximum energy lost is occurred when the energy of the a-particles is about 2MeV. The tracks' tip for incident alpha energies 1 and 2MeV appeared in a spherical phase which is called rounded or over etched phase ,while a sharp phase for energies 3,4 and 5MeV was investigated . It was found that the track's depth which is calculated by computer program greater than that measured experimentally and that the percentage difference between two can be about 38% for 3MeV.

In this work, we have used CR-39 detectors to estimate the LET (linear energy transfer) spectrum of secondary particles due to 171 MeV proton beam at different depths of water including the Bragg peak region. The measured LET spectra were compared with those obtained from FLUKA Monte Carlo simulation. The absorbed dose ( D LET ), dose equivalent ( H LET ) were estimated using the LET spectra. The values of D LET and H LET per incident proton fluence were found to increase with the increase in depth of water and were maximum at Bragg peak. [ABSTRACT FROM AUTHOR]

Continuous welded rail (CWR) track has several advantages when compared with conventional jointed rail track. However, a thermally induced axial load can lead to the buckling of CWR tracks, which can result in train derailment. The buckling of CWR tracks is affected by several parameters, including the rail’s neutral temperature, misalignment of the rails and ballast resistance. Most of these parameters can be considered as random variables. A deterministic analysis approach is generally used to predict the buckling of CWR tracks; however, it can provide conservative results since it is based on the worst-case scenario of these buckling parameters. This paper presents a probabilistic buckling analysis scheme for CWR tracks. [ABSTRACT FROM AUTHOR]

Cellulose nitrate LR-115 detectors were irradiated with alpha particles in the energy range from 1 to 5MeV at incident angles from 20° to 90°, using an 241Am source. After etching in a 2.5N NaOH solution kept at 60°C for various periods, the diameters of the major and minor axes of the track openings, track growing rate, track etch rate, etching ratio, and track length were found as a function of energies and incident angles. The measured track parameters were compared to calculated values, and the etching ratio was formulated as a Durrani–Green's function of the incident energy and angle. [ABSTRACT FROM AUTHOR]

Abstract: A new algorithm for the tracking of charged particles through timing detectors is proposed, providing as output the coordinates, slopes, velocity and an offset time at a given reference plane. The algorithm is based on a least squares method and works directly with first level data provided by the detectors, either coordinates or readout times. Some general analytical solutions valid for different detector layouts are given. Advantages compared to traditional straight track fitting algorithms are discussed. [ABSTRACT FROM AUTHOR]

Abstract: A new method, based on Digital Holographic Microscopy (DHM), to visualize and to analyze etched tracks in SSNTD has been developed. The proposed method is based on the possibility of the digital holography to perform whole reconstruction of the recorded wave front, so that phase and intensity distribution at a plane located between the object and recording plane and along the reconstructed image of the object can be determined. In a DHM system, the back focal plane of the lens can be reconstructed so that complex amplitudes of the Fraunhofer diffraction of light distribution across the object can be known. With the knowledge and manipulation of the components of this plane is possible to design different methods of image analysis. In this paper, the DHM method was applied to determine the track parameters in CR-39 detectors, showing that most of studies carried out with Confocal Microscopy and Atomic Force Microscopy could be also done, with the sufficient exactitude and precision, but in a simpler and more economic way. The developed microholographic method provides a new alternative procedure that overcomes the current techniques at least in technological simplicity. [ABSTRACT FROM AUTHOR]

Dynamic behavior of railway tracks when trains are running is influenced by several factors, i.e. rolling stock, the components of superstructure and their specifications. Usually, features like the sleeper spacing, rail pad stiffness, ballast damping and stiffness have an effect on the dynamic response of the track. The best method to study the dynamic behavior of the track is to model the track assembly and the train as a whole and carry out an analysis of dynamic interaction. Such analysis makes the identification of the track’s dynamic behavior easer and helps to anticipate the deterioration of the track elements, and determines the effects of increase or decrease of mentioned parameters. This paper presents track-train dynamic interaction without considering irregularity of the rail face. A sensitivity analysis was carried out on the selected model. The analysis was undertaken with the view of varying one of the mentioned parameters and the results were presented to further identify the deterioration of the track elements. The results indicate that reducing sleeper spacing, rail pad stiffness, ballast stiffness, and increasing ballast damping reduces wheel-rail, rail-sleeper, and sleeper - ballast contact forces. [ABSTRACT FROM AUTHOR]

Computer programs have been developed to calculate track parameters and to plot track openings and wall profiles. The programs are based on equations derived for three-dimensional consideration of track development. All possible cases of track openings and wall profiles are obtainable from these equations. Results are given for lengths of major and minor axes, track depths and surface areas of track openings. Some examples of track openings and wall profiles are also presented. [Copyright &y& Elsevier]

Three-dimensional analytical determinations of track parameters are extended to cases where the tracks are in the rounded and spherical phases of development. The equation for the track wall in three dimensions and the equation of contour line of the opening were derived for all types of tracks. The expression for the surface area of the track opening has also been found. The equations come up to the well-known expressions for minor and major axes for the special case of constant track etch rate. [Copyright &y& Elsevier]