Artykuły w czasopismach na temat „Track”
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Zou, Ke, Hao Zhu, Allan De Freitas, Yongfu Li i Hamid Esmaeili Najafabadi. "Track-to-Track Association for Intelligent Vehicles by Preserving Local Track Geometry". Sensors 20, nr 5 (4.03.2020): 1412. http://dx.doi.org/10.3390/s20051412.
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Track-to-track association (T2TA) is a challenging task in situational awareness in intelligent vehicles and surveillance systems. In this paper, the problem of track-to-track association with sensor bias (T2TASB) is considered. Traditional T2TASB algorithms only consider a statistical distance cost between local tracks from different sensors, without exploiting the geometric relationship between one track and its neighboring ones from each sensor. However, the relative geometry among neighboring local tracks is usually stable, at least for a while, and thus helpful in improving the T2TASB. In this paper, we propose a probabilistic method, called the local track geometry preservation (LTGP) algorithm, which takes advantage of the geometry of tracks. Assuming that the local tracks of one sensor are represented by Gaussian mixture model (GMM) centroids, the corresponding local tracks of the other sensor are fitted to those of the first sensor. In this regard, a geometrical descriptor connectivity matrix is constructed to exploit the relative geometry of these tracks. The track association problem is formulated as a maximum likelihood estimation problem with a local track geometry constraint, and an expectation–maximization (EM) algorithm is developed to find the solution. Simulation results demonstrate that the proposed methods offer better performance than the state-of-the-art methods.
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Wertheimer, Albert I. "Welcome track and trace". Journal of Pharmaceutical Health Services Research 7, nr 4 (11.11.2016): 207–8. http://dx.doi.org/10.1111/jphs.12158.
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Xing, Lida, Martin Lockley, Zhitao Wang, Jianjun Liu, W. Scott Persons IV, Bolin Tong i Liu Chang. "Dinosaur Track from the Jurassic Xiahuayuan Formation of Northern China". Biosis: Biological Systems 3, nr 1 (1.04.2022): e003. http://dx.doi.org/10.37819/biosis.003.01.0168.
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An isolated but moderately well-preserved theropod track from the coal-bearing strata of the Zhangjiakou City region of Hebei Province was reported to have originated from the Xiahuayuan Formation, which is considered Middle Jurassic in age. Although the track has a wide divarication angle and length-width ratio reminiscent of Cretaceous tracks like Magnoavipes, it would be speculative to apply this Identification based on a single track. Therefore, it is considered most likely to be a preservational variant of Kayentapus, in which the heel trace is lacking. Kayentapus is widely known from the Lower Jurassic of China. This is the first report of a track or any vertebrate fossil from the Middle Jurassic of this region of Hebei Province, China.
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Fedosov, A. D., i E. S. Antereykin. "Comparison of work volumes on maintenance of tram track sections on various stages of life cycle". Transport of the Urals, nr 2 (2021): 79–84. http://dx.doi.org/10.20291/1815-9400-2021-2-79-84.
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The paper presents the assessment of technical condition of track on the example of two tram sections on Titov and Svyazistov streets in Novosibirsk. The authors have compared sections by the number of derailments and have revealed the main reasons of the derailments. As a result, they have established the volumes of maintenance of tram tracks and the required labour costs, as well as the works that make the main share of labour costs for 5 years on both considered sections. In order to control the track position for the provision of comfortable and safe transportation of passengers the authors recommend to use a track measuring truck.
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O'Neill, Tanya A., Megan R. Balks i Jerónimo López-Martínez. "Ross Island recreational walking tracks: relationships between soil physiochemical properties and track usage". Polar Record 51, nr 4 (3.07.2014): 444–55. http://dx.doi.org/10.1017/s0032247414000400.
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ABSTRACTThe objective of this research was to determine the number of people using the Ross Island recreational walking tracks, and to examine the relationships between the number of users, track morphological characteristics, and soil physiochemical properties. Infrared track counters provided 2-years of data on five walking tracks on the island. Track width and track incision were measured and soil sampling in the vicinity of the track counter and an adjacent control site was undertaken. Between January 2009 and January 2011 5084 passes were recorded on the Scott Base to McMurdo Station walking track, 2842 on the Wind Vane Hill walking track, 3561 on the Round Observation Hill walking track, 10936 on the Up Observation Hill track, and 693 on the Crater Hill summit walking track. There were more users on all tracks in the 2010–2011 summer season than the 2009–2010 summer season. The highest frequency of visitors occurred on Sundays during the summer (November to January). There was no relationship between the number of passes on the track and the measured impact indicators. This indicates that higher usage of a formed track had little cumulative impact. Track width and incision were related to the slope of the terrain, with tracks traversing flatter areas generally wider (R2 = 0.85) and less incised (R2 = 0.96), than those traversing steeper hillsides. There were no significant differences between tracks and control samples in soil pH, soil EC, organic C, total N, and total P. However, soil bulk density was higher in the walking tracks than adjacent control areas (p < 0.05).
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Shibata, Masateru, i David J. Varricchio. "Horseshoe crab trace fossils from the Upper Cretaceous Two Medicine Formation of Montana, USA, and a brief review of the xiphosurid ichnological record". Journal of Paleontology 94, nr 5 (15.05.2020): 887–905. http://dx.doi.org/10.1017/jpa.2020.16.
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AbstractA locality in the Upper Cretaceous Two Medicine Formation of Montana preserves abundant and variable horseshoe crab tracks and trails of the ichnotaxon Kouphichnium isp. These specimens span six morphologies differing in track form and trail configuration. These differences likely reflect variations in track-maker locomotion and behavior, substrate consistency, epichnial versus hypichnial preservation, and undertrack versus true tracks. Several tracks preserve the first clear appendage impressions for an extinct horseshoe crab. This discovery adds new information to the fossil horseshoe crab diversity in the Cretaceous Period. Trackway dimensions, such as the external width across the pusher legs or of the prosomal drag mark, provide information on the track-maker size. Most trackways correspond with crabs 9–14 cm wide; the abundance but limited size range of the traces suggests the large assemblage corresponds to a mating aggregation. The trace fossil record of xiphosurids indicates that throughout their history, horseshoe crabs inhabited both marine and nonmarine settings. They were definitively present in freshwater habitats from the lower Carboniferous through at least the Paleogene. Horseshoe crab trace abundance is highest from the upper Carboniferous through the Jurassic and likely reflects two factors: true upper Carboniferous taxonomic diversity and a preponderance of suitable sites for trackway preservation in the Late Triassic and Jurassic. Cretaceous traces are uncommon, and this Two Medicine locality is the first occurrence of horseshoe crab traces in the Late Cretaceous worldwide. Overall, track abundance and diversity would seem to correspond well with the reported horseshoe crab body fossil record.
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Dong, Kai, Hai Peng Wang i Yu Liu. "Formation Track Association Algorithm in the Presence of Sensor Bias Based on Double Fuzzy Topology". Applied Mechanics and Materials 536-537 (kwiecień 2014): 329–32. http://dx.doi.org/10.4028/www.scientific.net/amm.536-537.329.
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Aiming to solve the track association problem of the formation targets in the presence of sensor bias, a formation track association algorithm based on double fuzzy topology (DFT-FTA) is proposed according to the topology characteristics of the formation tracks. The formations are identified among sensors tracks based on the circulatory threshold model firstly. Then the formation tracks are replaced by their center track so that the first fuzzy topology model is established to realize preparatory association of formation tracks and common tracks. At last, the second fuzzy topology model based on the associated formation tracks and associated common tracks is established to realize formation inner track association. The simulation result shows that the proposed algorithm outperforms the fuzzy track alignment-association algorithm based on target invariable information (TII-FTA) and modified weight track association algorithm (MW-TA).
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Zarei-Jalalabadi, Mahboubeh, Seyed M. B. Malaek i Solmaz S. Kia. "A Track-to-Track Fusion Method for Tracks With Unknown Correlations". IEEE Control Systems Letters 2, nr 2 (kwiecień 2018): 189–94. http://dx.doi.org/10.1109/lcsys.2017.2779465.
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Nikezic, Dragoslav, Peter Yu i Dragana Kostic. "Three-dimensional model of track growth: Comparison with other models". Nuclear Technology and Radiation Protection 18, nr 2 (2003): 24–30. http://dx.doi.org/10.2298/ntrp0302024n.
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Here, we present a three-dimensional model of track growth in nuclear track detectors. The equation for the track wall in three dimensions and the equation of the contour line of the track opening have been derived for all types of tracks (i. e., tracks with sharp tips and tracks with rounded tips). The expression for the surface area of the track opening has also been found. The equations become the well-known expressions for minor and major axes for the special case of constant track etch rates. Computations of track parameters based on our model have been compared with the track growth models given by Somogyi and Szalay and the one given by Fews and Henshaw. Good agreements have been found among these three independent models.
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Ouyang, Cheng, Hong Bing Ji i Jun Gen Zhang. "Improved Estimate-to-Track Association Method for Track Continuity". Key Engineering Materials 467-469 (luty 2011): 806–11. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.806.
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The probability hypothesis density (PHD) filter is a practical alternative to the optimal Bayesian multi-target filter based on finite set statistics. However, the PHD filter keeps no record of target identities and hence does not produce track-valued estimates of individual targets. To solve this problem, an improved estimate-to-track association method for track continuity is proposed in this paper. Firstly, a multi-step prediction of current target states is made, and then the weighted labels are assigned to them according to the inertia. Secondly, the fuzzy membership degrees of the current state estimates belonging to the tracks are obtained by utilizing the maximum entropy fuzzy clustering. Finally, the tracks are maintained by integrating all this information. Different from the traditional estimate-to-track association method, the proposed algorithm does not update the track information by simply summing the log likelihood ratios between adjacent scans, but take the entire multi-scan information into account by the operations such as weighting and clustering. The simulation results show that the proposed algorithm can maintain target tracks more accurately, even when the targets cross each other, implying strong robustness and excellent performance of track continuity.
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Lee, Jae-Ik, Kyu-Hwan Oh i Yong-Gul Park. "Separate Track Impact Factor Application Depending on Track Types through Correlative Analysis with Track Support Stiffness". Infrastructures 5, nr 2 (6.02.2020): 17. http://dx.doi.org/10.3390/infrastructures5020017.
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Track impact factor (TIF) is a coefficient for estimating the increase of train dynamic load and is a major factor for the evaluation of dynamic stability of railway tracks. Many kinds of TIF in ballasted and ballast-less slab tracks consider only speed as a variable in different regions of the world. Because of this lack of clarification, nations such as Korea and those in the Middle East, and South East Asia are implementing overly simplified calculation methods for TIF, resulting in inconsistent maintenance of different railway track types. A comparative analysis of theoretically track support stiffness (TSS) and trackside measurement calculated TSS at wheel-rail contact point shows different values (depending on speed) between ballasted and ballast-less slab tracks. Based on this finding, this paper investigates a TIF formulation method that considers both dynamic wheel load and speed as variables, and a separate application of TIF formulation depending on track types is proposed. A clarified distinction of how these parameters (TSS and TIF) interact differently between ballasted and ballast-less slab track structures can be an important factor in case of track designing and maintenance aspects.
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Šestáková, Janka. "Quality of Slab Track Construction – Track Alignment Design and Track Geometry". Civil and Environmental Engineering 11, nr 1 (1.05.2015): 2–9. http://dx.doi.org/10.1515/cee-2015-0001.
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Abstract The slab track superstructure design (without ballast) is a perspective construction especially for building tunnels and bridges in the modernized sections of railway tracks in Slovakia. Monitoring of the structure described in this article is focused on the transition areas between standard structure with ballast and slab track construction.
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Roskos, Steven E., Tyler W. Barreto, Julie P. Phillips, Valerie J. King, W. Suzanne Eidson-Ton i Aimee R. Eden. "Maternity Care Tracks at US Family Medicine Residency Programs". Family Medicine 53, nr 10 (5.11.2021): 857–63. http://dx.doi.org/10.22454/fammed.2021.237852.
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Background and Objectives: The number of family physicians providing maternity care continues to decline, jeopardizing access to needed care for underserved populations. Accreditation changes in 2014 provided an opportunity to create family medicine residency maternity care tracks, providing comprehensive maternity care training only for interested residents. We examined the relationship between maternity care tracks and residents’ educational experiences and postgraduate practice. Methods: We included questions on maternity care tracks in an omnibus survey of family medicine residency program directors (PDs). We divided respondent programs into three categories: “Track,” “No Track Needed,” and “No Track.” We compared these program types by their characteristics, number of resident deliveries, and number of graduates practicing maternity care. Results: The survey response rate was 40%. Of the responding PDs, 79 (32%) represented Track programs, 55 (22%) No Track Needed programs, and 94 (38%) No Track programs. Residents in a track attended more deliveries than those not in a track (at Track programs) and those at No Track Needed and No Track programs. No Track Needed programs reported the highest proportion of graduates accepting positions providing inpatient maternity care in 2019 (21%), followed by Track programs (17%) and No Track programs (5%; P<.001). Conclusions: Where universal robust maternity care education is not feasible, maternity care tracks are an excellent alternative to provide maternity care training and produce graduates who will practice maternity care. Programs that cannot offer adequate experience to achieve competence in inpatient maternity care may consider instituting a maternity care track.
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Auersch, Lutz, i Samir Said. "Slab Track Behaviour under Train Passage and Hammer Impact - Measurements at Different Sites and Calculated Track Interaction with Continuous Soils". International Journal of Acoustics and Vibration 25, nr 3 (30.09.2020): 341–54. http://dx.doi.org/10.20855/ijav.2020.25.31622.
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This contribution intends to give an overview on the vibration behaviour of slab tracks in comparison of measurements and calculations and -6mmalso-6mm by comparison of different track types at more than ten different measuring sites. In theory, tracks on -6mmcontinuous-6mm soil are calculated by the frequency-wavenumber domain method. In experiment, geophone measurements are transformed to displacement results. Two aspects of track behaviour are considered, the frequency-dependant compliance of the track, measured by hammer impact, and the deflection under a passing axle load. In theory, the response to a single axle can be calculated, whereas in experiment, only the passage of the whole train can be measured. For comparison of theory and experiment, the calculated deflection under a single axle is superposed to get the response of the whole train. As a result, the slab track characteristics are completely different from the ballast track characteristics where each axle can be seen in the time histories. The slab track has a more global behaviour where only a whole bogie can be found in the track response and moreover, the two neighbouring bogies are not completely separated. The measurement of the different track elements (rail, sleeper, track plate, base layer) and the frequency-dependant compliances with possible resonances yield further information about the properties of the track elements. The calculations show that the soil has the dominant influence on the amplitudes and the width of the track-plate displacements. In the measurement results, the following parameters are analysed: slab track vs.~ballast track, different types of slab tracks, damaged slab tracks, different trains, switches at different measuring points, voided sleepers, an elastic layer, the mortar layer, and different soils at different places. Finally, a good agreement between measured and calculated results is found for the normal and some special (damaged, floating) slab tracks.
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Xu, Peng, Reng-Kui Liu, Feng Wang, Fu-Tian Wang i Quan-Xin Sun. "Railroad Track Deterioration Characteristics Based Track Measurement Data Mining". Mathematical Problems in Engineering 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/970573.
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Accurate information on future railroad track condition is essential to optimally schedule track Maintenance & Renewal activities in order to minimize influences of the activities on rail traffic under constraints of limited budgets and maintaining allowable condition tracks. In this paper, a track measurement data mining method is presented to this aim. It is developed on the basis of track deterioration characteristics. Actual track measurement data is used to analyze errors in track condition predictions by the method. The analysis results show that the proposed method can mine accurate track deterioration rates from historical track measurement data and thus accurately provides future track condition two or three months in advance.
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Balekwa, Bingo Masiza, i Daramy Vandi Von Kallon. "Correlation of Short Pitch Rail Corrugation with Railway Wheel-Track Resonance at Low Frequencies of Excitation". Vibration 3, nr 4 (8.12.2020): 491–520. http://dx.doi.org/10.3390/vibration3040031.
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As much as there has been a significant increase in the development of railway systems in recent years, one of the significant drawbacks on this mode of transport is ground-borne vibrations and noise emanating from vehicle-track interaction in service. This greatly affects the ecology and physical surroundings of the railway track. Experimental tests and Finite Element modal and complex eigenvalue analysis are conducted to investigate the dynamics of a traction wheelset and rail track. This is done to establish the correlation between the short pitch rail corrugation in the Belfast to Steelpoort railway line, in the Limpopo Province of South Africa, with railway wheel-tract resonance at low frequencies of excitation. A 3D Finite Element Method (FEM) and complex eigenvalue analysis are used to validate the resonance modes of the wheelset and rail track obtained through experimental modal analysis. Mode shapes are determined for natural frequencies that match the excitation frequency induced by short pitch rail corrugation. The results show that based on average train speeds around track curves, the excitation frequency induced by corrugation matches (quite reasonably) natural frequencies of the wheelset. Whilst the wheelset FEM results are in better agreement, they rather prove the correlation to occur at 100 Hz. In a previous study by the authors, at the average speeds per track curve, the corrugation excitation frequency was found to be 108 Hz. The current study goes further by investigating natural frequencies of rail tracks. Moreover, mode shapes of a traction wheelset and rail tracks are also investigated, and the results are presented herein.
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Ketcham, Richard A., i Murat T. Tamer. "Confined fission-track revelation in apatite: how it works and why it matters". Geochronology 3, nr 2 (23.08.2021): 433–64. http://dx.doi.org/10.5194/gchron-3-433-2021.
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Abstract. We present a new model for the etching and revelation of confined fission tracks in apatite based on variable along-track etching velocity, vT(x). Insights from step-etching experiments and theoretical energy loss rates of fission fragments suggest two end-member etching structures: constant-core, with a central zone of constant etching rate that then falls off toward track tips; and linear, in which etching rates fall linearly from the midpoint to the tips. From these, we construct a characterization of confined track revelation that encompasses all relevant processes, including penetration and widening of semi-tracks etching in from the polished grain surface, intersection with and expansion of confined tracks, and analyst selection of which tracks to measure and which to bypass. Both etching structures are able to fit step-etching data from five sets of paired experiments of fossil tracks and unannealed and annealed induced tracks in Durango apatite, supporting the correctness of our approach and providing a series of insights into the theory and practice of fission-track thermochronology. Etching rates for annealed induced tracks are much faster than those for unannealed induced and spontaneous tracks, impacting the relative efficiency of both confined track length and density measurements and suggesting that high-temperature laboratory annealing may induce a transformation in track cores that does not occur at geological conditions of partial annealing. The model quantifies how variation in analyst selection criteria, summarized as the ratio of along-track to bulk etching velocity at the etched track tip (vT/vB), likely plays a first-order role in the reproducibility of confined length measurements. It also accounts for and provides an estimate of the large proportion of tracks that are intersected but not measured, and it shows how length biasing is likely to be an insufficient basis for predicting the relative probability of detection of different track populations. The vT(x) model provides an approach to optimizing etching conditions, linking track length measurements across etching protocols, and discerning new information on the underlying structure of fission tracks.
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Chavan, Sushma S., Amol M. Mhatre, Ashok K. Pandey i Hemlata K. Bagla. "Alpha track registration and revelation in CR-39 using new etching method for ultratrace alpha radioactivity quantification in solution media". Radiochimica Acta 109, nr 6 (17.05.2021): 503–12. http://dx.doi.org/10.1515/ract-2020-0010.
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Abstract A CR-39 based method was developed for measuring the ultra-trace alpha radio activities in aqueous samples having curie levels of γ/β-radio activities. The chemical etching method was optimized to reveal the alpha tracks in CR-39. This new chemical etching method involved the use of a phase transfer catalyst tetraethylammonium bromide which reduced the track revelation induction time without deteriorating the track-etch parameters. The alpha track-etch parameters such as bulk-etch rate, track-etch rate, induction time, and the critical angle of alpha track registration were measured at 60 and 70 °C, with and without using a phase transfer catalyst in the chemical etching for the comparison and optimization. The track registration efficiency of CR-39 in the solution medium was measured using the samples having known alpha activity of mixPu, and value obtained was found to be (4.42 ± 0.12) × 10−4 cm. The registration efficiency value thus obtained was corroborated with the expected efficiency expected from the calculated range of alpha particles in the solution. This CR-39 based method was employed to quantify the alpha activity, as low as 0.2 Bq mL−1, in the aqueous radiopharmaceutical samples having the curie levels of γ/β radio activities.
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Ižvolt, Libor, Jana Ižvoltová i Janka Šestáková. "Influence of Construction of Railway Superstructure on Railway Quality". Applied Mechanics and Materials 617 (sierpień 2014): 54–59. http://dx.doi.org/10.4028/www.scientific.net/amm.617.54.
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The operation of railway tracks is historically confirmed that the classic structure of the railway superstructure is capable to ensure operational capability of standard railway tracks for a relatively long period of time (railways tracks to speed of 160 km.h-1). Such a railway track and its track is considered the railway track with a classic structure of the railway superstructure, where track removal is stored in the ballast. In the case of high operating and axle load, increasing track speed and requirements for safety of operation, which are associated with high requirements on the track geometry, it appears that such structure has its operational (in terms of guaranteeing the long-term safety and reliability of the railway track) and economic (in terms of the cost of maintenance of railway track) limits. "Floating" placement of the track removal during each passage of a rail vehicle, or train leads to the growth of dynamic horizontal and vertical forces that cause gradual degradation of track geometry, what subsequently leads to restless journey of moving rail vehicles. Elimination of imperfections in track geometry - the quality of the railway track - forces the operators to remove such imperfections of railway track in time and financially consuming maintenance work in certain periods. However, it is sufficient if only the weakest element of classic railway superstructure is replaced in the railway, and it is the track ballast using other more appropriate component representing no elastic and plastic behaviour. The structure is such replacement, in which the track removal is concreted (monolithic structure) or stored on a concrete or asphalt bearing layer (layered structure), namely structural design, which is referred to as unconventional railway superstructure. The structure of railway superstructure is characterized by cross sleepers used in a modified shape or they are not part of it at all. Currently, thus conceived railway track is referred to as a slab track (hereinafter referred to as the "ST"), which requires flexibility of the railway superstructure for the system of the wheel/rail secured using elastic elements disposed between the rail and the sleeper and/or under the sleeper. In general, the structure of ST has been currently applied mainly to high-speed track and the tracks that have high operational load, where the cost of maintaining the track with the classic structure of the railway superstructure strongly grows. At the same time, however, this structure also promotes in the upgraded sections of the standard tracks (track speed to 160 km.h-1), especially in track sections conducted in tunnels, as there are located the required properties of the ballast that do not demonstrate subsidence. The subgrade without a drop also offers for application of the ST structure bridges, and therefore, the application of this structure is also possible in these track sections.
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Wehbi, Mohamed, i Niyazi Özgür Bezgin. "Proposal and Application of a New Technique to Forecast Railway Track Damage Because of Track Profile Variations". Transportation Research Record: Journal of the Transportation Research Board 2673, nr 4 (kwiecień 2019): 568–82. http://dx.doi.org/10.1177/0361198119836973.
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This paper presents a new technique to estimate dynamic impact forces on railway tracks that develop because of variations in track profile. The approach presented uses a wavelet decomposition method to systematically define the irregular profile variation of a rough track length in relation to regular wavelet functions. These functions provide the regular profile variation parameters to estimate the dynamic impact forces using a new method proposed by Bezgin. This paper begins with an introduction of the proposed Bezgin Method and two equations developed by this method to estimate dynamic impact force factors that develop along descending track profiles, followed by the presentation of the wavelet decomposition method to represent the irregular variations in rough track profiles by wavelet functions. The paper then presents three case studies that involve track profile and stiffness measurements and track damage data collection along three railway tracks in the United Kingdom and continues with the applications of the wavelet decomposition method to the measured variations in the track profiles. The equations developed by the Bezgin Method then make use of the processed profile data to estimate the dynamic impact force factors along the railway tracks. The paper ends by correlating the estimated dynamic impact force factors to the damage data collected along the tracks and shows that there is a relation between the observed track damage and the estimated dynamic impact force factors. The proposed technique has, therefore, the potential applications to assess railway track conditions and forecast railway track damage.
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Jóvér, V., M. Sysyn, J. Liu i S. Fischer. "Geometry variation of ballasted railway tracks due to weather conditions". Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, nr 1 (28.02.2023): 74–79. http://dx.doi.org/10.33271/nvngu/2023-1/074.
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Purpose. Investigate and establish the relationship between track geometry measurements and weather conditions to determine the parameters that influence the lifetime of railway tracks’ superstructure system. The study of ballasted beds of railway tracks is very important for operation and maintenance in case of main lines, industrial sidings and mine transport. Methodology. Determination of the annual load of the selected section based on the regulations. Compari of the track parameters measurements made by TrackScan 4.01 instrument in different seasons and temperatures. Among the parameters measured by the instrument, the track gauge, alignment, longitudinal level, and superelevation parameters are considered and analyzed in this article.Since the main lines’ traffic are permanently loaded with passenger and freight transport and the industrial sidings and mine tracks are used in the production process, the examinations can only be done on tramway tracks during the standstills at night. The results of these measurement on tramway tracks can help to understand the identify of railway tracks’ lifetime and can be used in mainlines, industrial and mining railway tracks. Findings. The change in the average values of selected track geometrical parameters is analyzed, considering the typical weather conditions. Based on the measurement and results, there is an evident connection between the evaluated results of track geometry measurements and the change in weather conditions. Originality. Finding the relationship between changes in track geometry values and weather conditions on the basis of an evaluation of track geometry measurements taken on average every third month. Practical value. The results can then be used as input data for determining the service life of the track superstructure in the case of tramways, mainlines, industrial and mining railway tracks.
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Chen, Zhaowei, Wanming Zhai i Qiang Yin. "Analysis of structural stresses of tracks and vehicle dynamic responses in train–track–bridge system with pier settlement". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 232, nr 2 (28.10.2016): 421–34. http://dx.doi.org/10.1177/0954409716675001.
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Pier settlement causes deformation of bridge structures, and further distorts the track structures placed on bridge decks, which may greatly affect the service life of the tracks and safe operation of trains. This study analyzes track stresses and vehicle dynamic responses in train–track–bridge system with pier settlement and determines the pier settlement safe value for high-speed railways with China Railway Track System (CRTS) II slab tracks. First, a detailed train–track–bridge dynamic model is established based on the train–track–bridge dynamic interaction theory. Verified with field experimental results, the model is utilized to calculate the dynamic responses of the vehicle–track–bridge system with different pier settlement values. Finally, the safe value of the pier settlement in the CRTS II slab track railway line is determined according to the limit of the vehicle dynamic indicators and the structural stresses of tracks. The results show that the vertical acceleration of the car body is more sensitive to pier settlement among all the vehicle dynamic indicators. Structural stresses of tracks caused by pier settlement appear at the positions of the pier with settlement and its two adjacent piers. The effect of train loads on the track stresses is much smaller than that of the pier settlement. It is important to adopt the structural stresses of tracks as the evaluation criteria of the pier settlement safe value than the vehicle dynamic indicators. Taking the effects of the bridge pier settlement, the vehicle load, the prestress effect, and the self-weight into consideration, the pier settlement safe value for the high-speed railway lines with the CRTS II slab track is 11.5 mm.
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Weiss, Daniel I. "A "TRACK" IS NOT A "TRACT"". Ophthalmic Surgery, Lasers and Imaging Retina 16, nr 7 (lipiec 1985): 457. http://dx.doi.org/10.3928/1542-8877-19850701-16.
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Thompson, Cheryl A. "Track-and-trace technology slowly progresses". American Journal of Health-System Pharmacy 64, nr 23 (1.12.2007): 2416–20. http://dx.doi.org/10.2146/news07070101.
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Colton, Chris. "A tract on track—an attack". Injury 32, nr 5 (czerwiec 2001): 347–48. http://dx.doi.org/10.1016/s0020-1383(01)00025-0.
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Yang, Lei, Qian Chen, Jun Tian i Dapeng Wu. "Robust track-and-trace video watermarking". Security and Communication Networks 5, nr 4 (30.03.2011): 353–63. http://dx.doi.org/10.1002/sec.319.
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Auersch, L. "Characteristics of train passages over slab tracks from measurements and different track–soil models: Damage detection and ground vibration reduction". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, nr 2 (6.03.2019): 142–60. http://dx.doi.org/10.1177/0954409719835036.
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The characteristics of train passages over intact or damaged slab tracks on different soils have been calculated by the finite-element boundary-element method or the wavenumber-domain method. The influence of track and soil parameters on the distribution of track displacements and soil forces has been analysed. The measured and calculated displacement time histories of train passages could be used to identify track damages such as loose sleepers or a loose track plate. The time histories and spectra of soil forces can explain the measured ground vibration reduction in the slab tracks. The calculated displacement and force distributions of slab tracks on continuous soils do not fulfil the Winkler hypothesis, and Winkler models should not be used for track analysis.
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Javaid, Omer, i Dong-Ho Choi. "Effect of Track Irregularities on the Response of Two-Way Railway Tracks". Applied Sciences 10, nr 1 (18.12.2019): 11. http://dx.doi.org/10.3390/app10010011.
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In predicting the response of track from a moving train only one track is generally considered. However, the effect of ground vibrations from one track and its effect on the nearby tracks has not been studied completely. Therefore, in the present paper, the effect of track irregularities and speed on the prediction of two-way tracks response is investigated. For this purpose, a three-dimensional dynamic finite element (FE) model capable of simulating interactions between the train and track by using a nonlinear hertz contact method was developed. The model uses tensionless stiffness between the wheel and rail to couple them. The model components including the sleeper, ballast, and soil domain are represented by solid brick elements. The rails are modeled as 3D Euler–Bernoulli beam elements. An iterative numerical algorithm was established for the integrations of the train and track interface. A comparative analysis was performed at various speeds and rail surface irregularity wavelengths. With the increase in speed, the results showed a significant increase in the adjacent tracks response and can induce much larger track vibrations at high frequency.
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Wang, Mingze, Chengbiao Cai, Shengyang Zhu i Wanming Zhai. "Experimental study on dynamic performance of typical nonballasted track systems using a full-scale test rig". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 231, nr 4 (4.03.2016): 470–81. http://dx.doi.org/10.1177/0954409716634751.
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This paper presents an experimental study on dynamic performance of China Railway Track System (CRTS) series track systems using a full-scale test rig. The test rig has been constructed based on 55.17 m long full-scale nonballasted tracks composed of four typical CRTS track elements in high-speed railways. First, the dynamic characteristics of different nonballasted tracks are investigated by conducting wheel-drop tests, where a wheel-drop testing vehicle with a dropping wheelset is devised to provide the wheel-drop load. The vibration levels of different track systems are assessed by the root-mean-square acceleration per one-third octave band, and the vibration transmission characteristics of the CRTS series tracks are evaluated by transfer functions. Further, a mathematical track model is used to extract the dynamic stiffness and damping coefficient of the four types of nonballasted track systems based on the wheel–rail impact response. The vibration characteristics, the dynamic stiffness, and damping coefficient of different nonballasted track systems under various wheel-drop heights are compared and discussed in detail.
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Chang, Edmund K. M., Yanjuan Guo, Xiaoming Xia i Minghua Zheng. "Storm-Track Activity in IPCC AR4/CMIP3 Model Simulations". Journal of Climate 26, nr 1 (1.01.2013): 246–60. http://dx.doi.org/10.1175/jcli-d-11-00707.1.
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Abstract The climatological storm-track activity simulated by 17 Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4)/phase 3 of the Coupled Model Intercomparison Project (CMIP3) models is compared to that in the interim ECMWF Re-Analysis (ERA-Interim). Nearly half of the models show significant biases in storm-track amplitude: four models simulate storm tracks that are either significantly (>20%) too strong or too weak in both hemispheres, while four other models have interhemispheric storm-track ratios that are biased by over 10%. Consistent with previous studies, storm-track amplitude is found to be negatively correlated with grid spacing. The interhemispheric ratio of storm-track activity is highly correlated with the interhemispheric ratio of mean available potential energy, and this ratio is biased in some model simulations due to biases in the midlatitude temperature gradients. In terms of geographical pattern, the storm tracks in most CMIP3 models exhibit an equatorward bias in both hemispheres. For the seasonal cycle, most models can capture the equatorward migration and strengthening of the storm tracks during the cool season, but some models exhibit biases in the amplitude of the seasonal cycle. Possible implications of model biases in storm-track climatology have been investigated. For both hemispheres, models with weak storm tracks tend to have larger percentage changes in storm-track amplitudes over the seasonal cycle. Under global warming, for the NH, models with weak storm tracks tend to project larger percentage changes in storm-track amplitude whereas, for the SH, models with large equatorward biases in storm-track latitude tend to project larger poleward shifts. Preliminary results suggest that CMIP5 model projections also share these behaviors.
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Koti, Daniel, John Powell, Himani Naesstroem i K. T. Voisey. "Powder catchment efficiency in laser cladding (directed energy deposition). An investigation into standard laser cladding and the ABA cladding technique". Journal of Laser Applications 35, nr 1 (luty 2023): 012025. http://dx.doi.org/10.2351/7.0000904.
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This paper investigates the efficiency of powder catchment in blown powder laser cladding (a directed energy deposition technique). A comparison is made between standard “track by overlapping track” cladding (“AAA” cladding) and “ABA” cladding, where the gaps left between an initial set of widely spaced tracks (“A” tracks), are filled in by subsequent “B” tracks. In both these techniques, the melt pool surface is the collection area for the cladding powder, and the shape of this pool can be affected by several parameters including cladding speed, intertrack spacing, and type of cladding technique. The results presented here are derived from of an analysis of high-speed videos taken during processing and cross sections of the resultant clad tracks. The results show that the first track in AAA cladding has a different melt pool shape to subsequent tracks, and that the asymmetry of the subsequent track melt pools results in a reduction in the powder catchment efficiency. In contrast to this, the geometry of the “B” track melt pools between their adjacent “A” tracks results in an enhanced powder catchment efficiency.
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Zhang, Luo, Haihong Zhu, Jiahe Liu i Xiaoyan Zeng. "Track evolution and surface characteristics of selective laser melting Ti6Al4V". Rapid Prototyping Journal 24, nr 9 (12.11.2018): 1554–62. http://dx.doi.org/10.1108/rpj-01-2018-0004.
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Purpose The purpose of this paper is to investigate the track evolution and surface characteristics of selective laser melting Ti6Al4V. Design/methodology/approach In the present paper, Ti6Al4V single-track, multi-track and bulk sample were formed at different scanning speed by selective laser melting (SLM). Then, the surface morphology, three-dimension profile and surface roughness were evaluated. The width of the single and multi-track was measured and compared. Findings The results showed that the heat accumulation played a great role on the evolution of tracks and surface characteristics from single-track to multi-track and to bulk. The surface morphology of the subsequent tracks became more regular when the single-track was irregular at the same high scanning speed. The width of last track Wn was always larger than that of the first track W1. The Ra of the top of the bulk increased with the increase of the scanning speed, this trend was as same as the Ra of the single-track, but the trend of Ra of the side was opposite. Originality/value The effect of heat accumulation on the track evolution and surface characteristics is obtained. The results can help to derive a smooth surface with a regular and continuous track in SLM.
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Huh, Kunsoo, Chung Choo Chung, I. M. Kim i Mun-suk Suh. "Track Tension Controller Design and Experimental Evaluation in Tracked Vehicles". Journal of Dynamic Systems, Measurement, and Control 126, nr 4 (1.12.2004): 764–71. http://dx.doi.org/10.1115/1.1852461.
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Track tension is closely related to the maneuverability of tracked vehicles and the durability of their tracks and suspension systems. The tension needs to be maintained at an optimum level throughout the maneuver in order to minimize the excessive load on the tracks and to prevent track peeloff from the sprocket. In this paper, a track tension control system is developed for tracked vehicles which are subject to various maneuvering tasks. It consists of track tension estimator, track tension controller, and hydraulic unit. The tension around the idler and sprocket is estimated in real time, respectively. Using the estimated track tension and considering the highly nonlinear vehicle characteristics, a fuzzy logic controller is designed in order to control the track tension in the vehicles. The performance of the proposed tension control system is verified through simulation and experimental field tests.
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Shi, Li, Xiaoqiang Ye, Pengfei Zhang i Lin Guo. "A Comparative Study on Vertical Dynamic Responses of Three Types of Elevated Railway Tracks Subjected to a Moving Train". Mathematical Problems in Engineering 2019 (25.08.2019): 1–11. http://dx.doi.org/10.1155/2019/3290958.
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A theoretical model incorporating the moving train, the railway track, and the elevated viaduct is established and then solved using periodic theory in this paper. The vertical wheel/rail forces and the dynamic responses of track and viaduct girder are obtained and compared for three different types of tracks, i.e., the double-block ballastless track, the rubber-pad floating slab track, and the steel-spring floating slab track. It is observed that the rubber-pad and steel-spring floating slab tracks can reduce more than 10% of the wheel/rail force and the reaction force at girder supports, when compared to those of the double-block ballastless track. Especially, the steel-spring floating slab track develops an uplifting force larger than the installation force of the fastening clip, which may cause failure of the rail fastening system.
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Mehrali, Mohammad, Morteza Esmaeili i Saeed Mohammadzadeh. "Application of data mining techniques for the investigation of track geometry and stiffness variation". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, nr 5 (25.04.2019): 439–53. http://dx.doi.org/10.1177/0954409719844885.
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Railway tracks are one of the most important national assets of many countries. The major part of the annual budget of railway companies concerns repairing, improving, and maintaining railway tracks, which is a challenge for railway managers. The logical method of repair and maintenance should take into account all the economic and technical aspects of the problem and proper management of track maintenance—without knowing the factors and parameters responsible for the track failure—quality control methods, and finally, the choice of the appropriate repair methods. Railway track geometry is the main factor that identifies the track behavior and condition. It is based on measuring the geometric parameters of the track determined by the track quality indices. The existing track quality indices mostly represent the geometrical condition of the railway track superstructure. In the past years, the effects of track bed stiffness on the track condition have been investigated. This paper investigates the railway track condition based on the railway track geometry parameters as well as the vertical track stiffness. A method for continuous measurement of track stiffness along a railway line is described and demonstrated. By measuring the track geometry parameters and stiffness, the superstructure and the substructure condition of the railway track are assessed. In addition, the relation between these data is investigated by using data mining techniques such as classification, decision tree, clustering, and dominant wavelength filtering. It is shown that filtering the data based on the dominant wavelength provides the best correlation between the track geometry in the vertical direction and stiffness.
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Choi, Jungyoul. "Retracted: Influence of Track Support Stiffness of Railway Tracks on Track Impact Factor". Journal of Engineering Mechanics 140, nr 8 (sierpień 2014): 04014052. http://dx.doi.org/10.1061/(asce)em.1943-7889.0000744.
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Booth, James F., Young-Oh Kwon, Stanley Ko, R. Justin Small i Rym Msadek. "Spatial Patterns and Intensity of the Surface Storm Tracks in CMIP5 Models". Journal of Climate 30, nr 13 (lipiec 2017): 4965–81. http://dx.doi.org/10.1175/jcli-d-16-0228.1.
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To improve the understanding of storm tracks and western boundary current (WBC) interactions, surface storm tracks in 12 CMIP5 models are examined against ERA-Interim. All models capture an equatorward displacement toward the WBCs in the locations of the surface storm tracks’ maxima relative to those at 850 hPa. An estimated storm-track metric is developed to analyze the location of the surface storm track. It shows that the equatorward shift is influenced by both the lower-tropospheric instability and the baroclinicity. Basin-scale spatial correlations between models and ERA-Interim for the storm tracks, near-surface stability, SST gradient, and baroclinicity are calculated to test the ability of the GCMs’ match reanalysis. An intermodel comparison of the spatial correlations suggests that differences (relative to ERA-Interim) in the position of the storm track aloft have the strongest influence on differences in the surface storm-track position. However, in the North Atlantic, biases in the surface storm track north of the Gulf Stream are related to biases in the SST. An analysis of the strength of the storm tracks shows that most models generate a weaker storm track at the surface than 850 hPa, consistent with observations, although some outliers are found. A linear relationship exists among the models between storm-track amplitudes at 500 and 850 hPa, but not between 850 hPa and the surface. In total, the work reveals a dual role in forcing the surface storm track from aloft and from the ocean surface in CMIP5 models, with the atmosphere having the larger relative influence.
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Cohen, Andrew S., James Halfpenny, Martin Lockley i Ellinor Michel. "Modern vertebrate tracks from Lake Manyara, Tanzania and their paleobiological implications". Paleobiology 19, nr 4 (1993): 433–58. http://dx.doi.org/10.1017/s009483730001407x.
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We studied mammal and bird track formation at the northern edge of Lake Manyara, Tanzania, to develop models for interpreting fossil tracks and trackways. Lake Manyara is a closed-basin, alkaline lake in the East African Rift System. The area has a high vertebrate diversity, allowing us to investigate tracks in an environment similar to that of many ancient track-bearing sequences. Three study sites, two on mud flats adjacent to the lake margin and a third on a delta floodplain, provided contrasting environments in which to assess the types of biological data that can potentially be extracted from fossil trackways.Our censuses of mammals and their tracks revealed that most species that occur within the study area leave a track record, and that common species leave abundant tracks, although numbers of trackways are not proportional to numbers of individuals. Logarithmic increases in track sampling area yield a linear increase in the proportion of both the medium and large-sized local mammals represented in a track record. Transect vs. area mapping methods produced different censusing results, probably because of differences in monitoring periods and areal coverage.We developed a model of expected track production rates that incorporates activity budget and stride length data in addition to abundance data. By using these additional variables in a study of diurnal birds, we obtained a much better estimator relating track abundance to trackmaker abundance than that provided by census data alone. Proportions of different types of tracks predicted by the model differ significantly from the observed proportions, almost certainly because of microenvironmental differences between the censusing and track counting localities. Censuses of fossil tracks will be biased toward greater numbers of depositional-environment generalists and away from habitat-specific species.Trackways of migratory animals were dominantly shoreline-parallel, whereas trackways of sedentary species were more variable. A strong shoreline-parallel environmental zonation at the Alkaline Flats site exerted an influence on trackmaker distribution patterns, initial track formation, and track preservation. Variations in habitat usage by different species, as well as species abundance and directionality of movement, were all important in determining the number of preservable tracks a species produced within a given environmental zone.Fossil trackways are time-averaged, although over entirely different temporal scales than are bones. Unlike bones, tracks are not space-averaged. Therefore, wherever possible, fossil track and bone studies should be used to complement each other, as they provide fundamentally different pictures of paleocommunities. Tracks provide “snapshot” views of localized assemblages of organisms useful in reconstructing autecological relationships, whereas bones yield a broader image of a local fauna in which seasonal and microenvironmental variation are more commonly smoothed out.
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Ngamkhanong, Chayut, Chuah Ming Wey i Sakdirat Kaewunruen. "Buckling Analysis of Interspersed Railway Tracks". Applied Sciences 10, nr 9 (29.04.2020): 3091. http://dx.doi.org/10.3390/app10093091.
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Nowadays, timber sleepers are still used for ballasted railway tracks to carry passengers and transport goods. However, the process of natural decay causes the problem of timber sleeper degradation over time. A temporary “interspersed” approach is used to replace rotten timbers with concrete sleepers. This implementation has several inadequacies, as interspersed railway tracks have inconsistent stiffness and experience significant deterioration over the years. Increased heat due to the change in the global climate can induce a compression force in the continuous welded rail (CWR), leading to a change in track geometry called “track buckling”. A literature review shows that track buckling on plain tracks has been widely studied. However, the buckling of interspersed tracks has not been fully studied. This study presents 3D finite element modelling of interspersed railway tracks subjected to temperature change. The effect of the boundary conditions on the buckling shape is considered. The obtained results show that the interspersed approach may reduce the likelihood of track buckling. This study is the world’s first to investigate the buckling behaviour of interspersed railway tracks. The insight into interspersed railway tracks derived from this study will underpin the life cycle design, maintenance, and construction strategies related to the use of concrete sleepers as spot replacement sleepers in ageing railway track systems. The outcome of this study will help track engineers to improve the inspection of the lateral stiffness of interspersed tracks in areas prone to extreme temperature.
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Balcı, Erdem, Niyazi Özgür Bezgin i Mohamed Wehbi. "Variation of Track Response to Wheel Forces with Bogie Axle Spacing: Apparent Track Stiffness and its Influence on Dynamic Impact Forces on Railway Tracks". Transportation Research Record: Journal of the Transportation Research Board 2676, nr 4 (17.12.2021): 570–88. http://dx.doi.org/10.1177/03611981211062487.
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Track stiffness is an important parameter that affects railway track response. Axle spacing influences the response of the track to wheel forces and has an effect on track stiffness. Track response to train wheels within a bogie or between neighboring bogies vary in relation to their mutual interference, depending on the mechanical characteristics of the layers composing the track, axle spacing and bogie spacing. This interference affects the force-deflection characteristic of the railway track under a wheel. Dynamic impact forces caused by track and wheel roughness relate to track stiffness. Therefore, everything else being the same, two trains with different bogie spacing may generate different dynamic impact forces on the railway track. As a result, the accumulated damage to a railway track over time can relate not only to cumulative tonnage but also to the axle spacing of the trains operating on the railway track. Through superposition of the estimated track deflections by the beam-on-elastic-foundation theorem and looking at it from a new perspective, this paper discovers a set of relations between the variations of track stiffness with bogie axle spacing. The paper introduces a new concept of apparent track stiffness and hypothesizes that dynamic impact forces on the railway tracks relate to axle spacing. The paper then presents a numerical study and an analytical study that analyzes wheel and track interaction along stiffness transition zones for different values of axle spacing and shows that bogie axle spacing has an effect on dynamic impact forces on railway tracks.
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Ahac, Maja, i Stjepan Lakušić. "TRAM TRACK MAINTENANCE-PLANNING BY GAUGE DEGRADATION MODELLING". TRANSPORT 30, nr 4 (18.12.2015): 430–36. http://dx.doi.org/10.3846/16484142.2015.1116464.
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Tram track system management is a complex, costly and interdisciplinary process. It involves construction, monitoring and maintenance of track infrastructure and rolling stock, and public transport organization. Track management cost reduction requires development of a modern management system that is based on integration and mutual complementarity of engineering and maintenance activities. The first step of its establishment is increasing the proportion of planned predictive-preventive track maintenance at the expense of corrective maintenance. This requires creation of a maintenance-planning model. Its basic prerequisite is the development of a mathematical model of tram track degradation during exploitation. The research presented in this paper describes the creation of mechanisticempirical models for tram tracks (narrow) gauge degradation by adopting the modelling methodology used on the classic railway constructions. Two types of tram tracks are observed: tracks with indirect elastic rail fastening system and stiffer direct elastic rail fastening system. These models represent the first step towards establishing a predictive maintenance system on Zagreb tram tracks.
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Pokropski, Dominik. "Methods used to prevent loss of contactless track stability". Bulletin of the Military University of Technology 69, nr 1 (31.03.2020): 23–34. http://dx.doi.org/10.5604/01.3001.0014.2783.
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The article is about the issue of maintaining a contactless track. Due to the forces occurring in the track, arising from both temperature changes and from rolling stock rolling on the track, it is necessary to monitor a displacement of rail tracks and stress in rails. The article presents a summary of the methods for monitoring the contactless track condition. The comparison of the methods was also presented, showing the pros and cons of each of them. Keywords: contactless track, contactless track buckling, track stress
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Kong, Gyuyeol, i Minchae Jung. "Tabu Search Aided Multi-Track Detection Scheme for Bit-Patterned Media Recording". Applied Sciences 12, nr 19 (28.09.2022): 9783. http://dx.doi.org/10.3390/app12199783.
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A tabu search (TS) aided multi-track detection scheme for bit patterned magnetic recording is proposed. The proposed detection scheme adopts the simplified multi-track detector with a two-dimensional generalized partial response (GPR) target, uses a priori information, and employs a reliability test and a TS detector. The proposed detection scheme processes signals in three stages. First, the single-track detector with a one-dimensional GPR target detects the data for the main-track and side-tracks. Second, the reliability test is performed to detect bits with low reliability in the side-tracks by comparing the distance between the readback signal and the estimated and reconstructed readback signal. If the distance is greater than a specific value, the TS detector is conducted to improve the reliability of bits with low reliability in the side-tracks. Lastly, the simplified multi-track detector detects the main-track data using a priori information from the outputs of the TS or single-track detectors for the side-track data. The proposed and conventional detection schemes are compared in terms of the bit error rate performances. Simulation results show that the proposed detection scheme with slightly additional complexity has more than 3 dB gains compared to the conventional detection schemes.
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Niyazgulov, F. Kh, i A. V. Krivous. "Investigation of the determination accuracy of the railway track spatial position by the Gedo track measuring trolley". Vestnik SSUGT (Siberian State University of Geosystems and Technologies) 27, nr 5 (2022): 124–37. http://dx.doi.org/10.33764/2411-1759-2022-27-5-124-137.
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The implementation of the concept of integrated development of the scientific and technical project "Digital Railway" provides for the development of digital technologies in all areas of activity of JSC "Russian Railways", including the track economy. In order to monitor the current state of the tracks, digital models of the tracks are created and maintained at the level of modern requirements, used to collect, store and evaluate spatial data on the current state of the tracks and develop recommendations for the prevention and elimination of identified malfunctions. The most effective and universal means of controlling and straightening the track is the coordinate method based on a system of continuous coordinate-digital description of the track in a single coordinate system. Track measuring wagons widely used in the railway network do not allow obtaining the geometric parameters of the track in a single coordinate system. Because of this, in our country and in foreign countries, various track-measuring systems have been developed and are used, allowing to obtain the CMR in coordinates. Therefore, the purpose of theoretical and experimental research is to identify the accuracy of determining the geometric parameters of the railway track using the Gedo track measuring trolley. The method of determining the track geometry, technical characteristics and distinctive features of the Gedo track measuring trolley are considered. A program of experimental studies is described and comparative accuracy estimates of the railway track geometry determination by the geodetic method, using a Gedo track measuring trolley and a rail gauge template are given. It is shown that in connection with the transition of the railway industry to digital technologies for modeling infrastructure facilities, it is most expedient to use the Gedo track measuring trolley for monitoring the geometry of the railway track, which provide the required accuracy of determining the geometry of the track, productivity and obtaining the necessary information in a single coordinate system.
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Levy, Joseph S., Andrew G. Fountain, Michael N. Gooseff, J. E. Barrett, Robert Vantreese, Kathy A. Welch, W. Berry Lyons, Uffe N. Nielsen i Diana H. Wall. "Water track modification of soil ecosystems in the Lake Hoare basin, Taylor Valley, Antarctica". Antarctic Science 26, nr 2 (10.07.2013): 153–62. http://dx.doi.org/10.1017/s095410201300045x.
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AbstractWater tracks are zones of high soil moisture that route shallow groundwater down-slope, through the active layer and above the ice table. A water track in Taylor Valley, McMurdo Dry Valleys, was analysed for surface hydrogeological, geochemical, and biological characteristics in order to test the hypothesis that water tracks provide spatial structure to Antarctic soil ecosystems by changing the physical conditions in the soil environment within the water tracks from those outside the water tracks. The presence of the water track significantly affected the distribution of biotic and abiotic ecosystem parameters: increasing soil moisture, soil salinity, and soil organic matter within the water track relative to soils outside the water track, and reducing soil phosphate, soil pH, and the population of nematodes and other invertebrates in water track soils relative to off track soils. These results suggest that water tracks are distinct and extreme ecological zones in Taylor Valley that provide long-range (kilometre to multi- kilometre) structure to Antarctic hillslope ecosystems through physical control on soil moisture and solute content. Contrary to expectations, these high soil-moisture sites are not hotspots for faunal biological activity because high soil salinity makes them suitable habitats for only the most halo-tolerant organisms.
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Nakamura, Jennifer, Upmanu Lall, Yochanan Kushnir, Patrick A. Harr i Kyra McCreery. "Early Season Hurricane Risk Assessment: Climate-Conditioned HITS Simulation of North Atlantic Tropical Storm Tracks". Journal of Applied Meteorology and Climatology 60, nr 4 (kwiecień 2021): 559–75. http://dx.doi.org/10.1175/jamc-d-20-0237.1.
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AbstractWe present a hurricane risk assessment model that simulates North Atlantic Ocean tropical cyclone (TC) tracks and intensity, conditioned on the early season large-scale climate state. The model, Cluster-Based Climate-Conditioned Hurricane Intensity and Track Simulator (C3-HITS), extends a previous version of HITS. HITS is a nonparametric, spatial semi-Markov, stochastic model that generates TC tracks by conditionally simulating segments of randomly varying lengths from the TC tracks contained in NOAA’s Best Track Data, version 2, dataset. The distance to neighboring tracks, track direction, TC wind speed, and age are used as conditioning variables. C3-HITS adds conditioning on two early season, large-scale climate covariates to condition the track simulation: the Niño-3.4 index, representing the eastern equatorial Pacific Ocean sea surface temperature (SST) departure from climatology, and main development region, representing tropical North Atlantic SST departure from climatology in the North Atlantic TC main development region. A track clustering procedure is used to identify track families, and a Poisson regression model is used to model the probabilistic number of storms formed in each cluster, conditional on the two climate covariates. The HITS algorithm is then applied to evolve these tracks forward in time. The output of this two-step, climate-conditioned simulator is compared with an unconditional HITS application to illustrate its prognostic efficacy in simulating tracks during the subsequent season. As in the HITS model, each track retains information on velocity and other attributes that can be used for predictive coastal risk modeling for the upcoming TC season.
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Vu, Linh, Dong-Doo Jang i Yun-Suk Kang. "Assessment of Structural Dynamic Response and Vehicle-Track Interaction of Precast Slab Track Systems". Applied Sciences 11, nr 8 (15.04.2021): 3558. http://dx.doi.org/10.3390/app11083558.
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Recently, precast slab tracks have been used widely in railway applications, especially in conventional urban railway lines. These types of tracks are rapidly constructed and limit interruptions to train operation. However, the problems of dynamic stability when the trains run on the discontinuous type of tracks must be seriously considered. This paper focuses on analyzing the train-track interaction in two types of tracks under the dynamic load by using the numerical analysis program (APATSI) to evaluate the structural response as well as the running safety to precisely understand the load transfer efficiency of precast slab track systems.
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Zakeri, Jabbar Ali, Roshan Talebi i Fatemeh Rahmani. "Field investigation on the lateral resistance of ballasted tracks with strengthened steel sleepers using the multi sleeper push test". Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 234, nr 9 (26.09.2019): 969–75. http://dx.doi.org/10.1177/0954409719877776.
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Lack of lateral resistance is one of the emerging problems in continuously welded rails. Lateral resistance is a type of resistance in which the railway track mobilizes against the applied lateral forces. Thus, curved tracks, especially sharp curves (curves with small radiuses), are the most susceptible segments for the lack of lateral resistance. The reason is, on curved tracks, in addition to the lateral forces applied by the train, longitudinal forces are decomposed into two parts, with one part being tangential (tangent to the curve) and the other part being radial. This radial force causes some defects to the track such as track buckling, transversal shifting of the track, pulling out of fastening shoulders, etc. Therefore, according to the general track instructions, welding of rails is not possible on curved tracks with a radius less than 400 m. With the help of laboratory tests, the authors of this paper previously showed that using two stiffeners under the steel sleeper increased the lateral resistance of the track adequately (by 140%) compared to the track with normal steel sleepers. In this paper, the effect of using two plate stiffeners under the steel sleepers was examined by field investigation on a real track. Two test methods, including the Single Tie (sleeper) Push Test (STPT) and the Multiple Tie (sleeper) Push Test (MTPT), were used to investigate the lateral resistance of the track. The results obtained by the STPT and MTPT methods showed an increase in lateral resistance by 139.6% and 135.5%, respectively. The obtained results are in accordance with the results of the laboratory tests. Moreover, the results showed that using two stiffeners under steel sleepers increased the lateral resistance of the track adequately, thereby enabling rails to be welded on curved tracks.
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Patiris, D. L., K. Blekas i K. G. Ioannides. "A MATLAB code for recognition and counting of track images". HNPS Proceedings 14 (5.12.2019): 119. http://dx.doi.org/10.12681/hnps.2259.
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A computer program named TRIAC written in MATLAB has been developed for track recognition and track parameters measurements from images of Solid State Nuclear Track Detectors CR39. The program using image analysis tools counts the number of tracks and classifies the tracks according to their radii. Comparison of manual scanning counts with those output by the automatic system are presented for detectors exposed to a radon rich environment. The system was also tested to differentiate tracks recorded by alpha particles of different energies
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Ding, Zhao, Yaoming Li i Zhong Tang. "Theoretical Model for Prediction of Turning Resistance of Tracked Vehicle on Soft Terrain". Mathematical Problems in Engineering 2020 (20.03.2020): 1–9. http://dx.doi.org/10.1155/2020/4247904.
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Skid-steered tracked vehicles are commonly used in soft agricultural terrain due to its low ground pressure between vehicle tracks and the ground. However, the sliding and sinkage of the track during a turning maneuver causes considerable turning resistance, which reduces the vehicle's turning ability. Therefore, we constructed a theoretical model that predicts the turning resistance of tracked vehicles—under steady-state conditions on soft terrain—accounting for track sinkage effects and track slip and skid. The results demonstrate that the moment of turning resistance decreases with increased track slip and skid ratio but increases with track sinkage depth. The model-predicted moments of turning resistance for the outer and inner tracks—at a given track sinkage depth and track slip and skid ratio—are in reasonably close agreement with available experimental data. This theoretical model can be employed as a predictor for testing the turning resistance of tracked vehicles operating on a wide range of soils.