Journal articles on the topic 'Rail surface temperatures'
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Chapman, L., J. E. Thornes, Y. Huang, X. Cai, V. L. Sanderson, and S. P. White. "Modelling of rail surface temperatures: a preliminary study." Theoretical and Applied Climatology 92, no. 1-2 (June 27, 2007): 121–31. http://dx.doi.org/10.1007/s00704-007-0313-5.
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Alizadeh Otorabad, Hossein, Parisa Hosseini Tehrani, Davood Younesian, Jilt Sietsma, and Roumen Petrov. "Analytical Formulation for Temperature Evolution in Flat Wheel-Rail Sliding Surfaces." Mathematical Problems in Engineering 2018 (November 12, 2018): 1–7. http://dx.doi.org/10.1155/2018/4239658.
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Studying the temperature evolution of the thermally affected zone (TAZ) of sliding surfaces is crucial because of its influence on microstructural evolution, wear, and fatigue. Due to the complexity of thermal analysis of sliding bodies, relationships that predict their surface temperature evolution are very helpful because they can be used as time-dependent boundary conditions; this makes the thermal analysis of sliding bodies independent. In this paper, by assuming thermal contact conductance (TCC) at the sliding common surface, the differential equation governing the thermal analysis of the wheel-rail sliding is solved throughout a wheel flat. The temperature evolution of wheel and rail surfaces and the heat partitioning factor are among the main results. Finally, the equations obtained for wheel and rail surface temperatures are applied to a freight wagon and a passenger car as two real cases. The results are discussed and compared to existing data in the literature and a solid agreement is achieved.
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Mirković, Nikola, Ljiljana Brajović, Zdenka Popović, Goran Todorović, Luka Lazarević, and Miloš Petrović. "Determination of temperature stresses in CWR based on measured rail surface temperatures." Construction and Building Materials 284 (May 2021): 122713. http://dx.doi.org/10.1016/j.conbuildmat.2021.122713.
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Hsu, Li-Shan, Pao-Chang Huang, Chih-Cheng Chou, Kung-Hsu Hou, Ming-Der Ger, and Gao-Liang Wang. "Effect of Nickel–Phosphorus and Nickel–Molybdenum Coatings on Electrical Ablation of Small Electromagnetic Rails." Coatings 10, no. 11 (November 10, 2020): 1082. http://dx.doi.org/10.3390/coatings10111082.
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The electromagnetic rail catapult is a device that converts electrical energy into kinetic energy, which means that the strength of electrical energy directly affects the muzzle speed of armature. In addition, the electrical conductivity, electromagnetic rails and armature surface roughness, and the holding force of the rail are influencing factors that cannot be ignored. However, the electric ablation on the surface of the electromagnetic rails caused by high temperatures seriously affects the service life performance of the electromagnetic catapult system. In this study, electrochemically deposited nickel-phosphorus and nickel-molybdenum alloy coatings are plated on the surface of electromagnetic iron rails and their effects on the reduction of ablation are investigated. SEM (scanning electron microscopy) with EDS (energy dispersive spectroscopy) detector, XRD (X-ray diffraction), 3D optical profiler, and Vickers microhardness tester are used. Our results show that the sliding velocity of the armature decreases slightly with the increased roughness of the rail coating surface. On the other hand, the area of electric ablation on the rail surface is inversely related to the hardness of the rail material. The electrically ablated surface areas of the rails are in: annealed nickel–molybdenum < nickel–molybdenum < annealed nickel–phosphorus < nickel–phosphorus < iron material. Heat treatment at 400 and 500 °C, respectively for Ni–P and Ni–Mo alloys, significantly increases hardness due to the precipitation of intermetallic compounds such as Ni3P and Ni4Mo phases. Comprehensive data analysis shows that the annealed nickel–molybdenum coating has the best electrical ablation wear resistance. The possible reason for that might be attributed to the high hardness of the heat-treated nickel–molybdenum coating. In addition, the thermal resistance capability of molybdenum is better than that of phosphorus, which might also contribute to the high wear resistance to electric ablation.
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Mazov, Yuriy Nikolaevich, Aleksey Alekseevich Loktev, and Vyacheslav Petrovich Sychev. "Assessing the influence of wheel defects of a rolling stockon railway tracks." Vestnik MGSU, no. 5 (May 2015): 61–72. http://dx.doi.org/10.22227/1997-0935.2015.5.61-72.
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Transfer of the load from the wheels on the rail occurs at a very small area compared with the size of the wheels and rails. The materials near this site have a very large voltage. Determination of contact stresses is complicated by the fact that the magnitude of these stresses in the rails under actually revolving wheel load exceeds the yield and compressive strength of modern rail steel. We should note that the metal of the rail head, experiencing contact stresses, especially when the location of the pads is closer to the middle of the rail head, works in the conditions close to the compression conditions, and therefore can withstand higher voltage without plastic deformation than the standard compressible sample. But, as a rule, the observed hardening of the metal in the zone of contact stresses and lapping at the edges of the rail head indicates the presence of plastic deformation and, consequently, higher stresses in the wheel-rail contact zone than the yield strength of the metal rail even in the conditions of its operation in the rail head.The use of the design equations derived on the basis of the Hertz theory for metal behavior in elastic stage, is valid. The reason is that each individual dynamic application of wheel loads on the rail is very short, and the residual plastic deformation from the individual loads of the pair of wheels on the rail is actually small. This elastic-plastic deformation of the rail becomes visible as a result of gradual gaining of a missed tonnage of rails and wheels respectively. Irregularities on the running surface of the wheels are of two types. The most common are the so-called continuous bumps on the wheel, when due to the uneven wear of rail the original shape of the wheel across the tread surface distorts. But nowadays, more and more often there occur isolated smooth irregularities of the wheel pairs, due to the increased wear of the wheel because of the stopping and blocking of wheels of the vehicles - slides (potholes), etc.The motion of the wheels with irregularities on the surface of the rail leads to vertical oscillation of the wheel, resulting in the forces of inertia, which is an additional load on the rail. In case of movement of the wheel with isolated roughness on the tread surface of the slide there is a strike, having a very large additional impact on the rail. Such attacks can cause kinked rails, especially in the winter months when there is increased fragility of rail steel, because of lowered temperatures. This is an abnormal phenomenon and occurs relatively rarely, at a small number of isolated irregularities on a wheel of the rolling stock. As correlations connecting the contact force and local deformation in the interaction of the wheel-rail system, we use the quasi-static Hertz’s model, linear-elastic model and two elastoplastic contact models: Alexandrov-Kadomtsev and Kil’chevsky. According to the results of Loktev’s studies ratios of the contact Hertz’s theory are quite suitable for modeling the dynamic effects of wheel and rail for speeds up to 90 km/h for engineering calculations. Since the contact surface is homogeneous and isotropic, the friction forces in the contact zone are not taken into account, the size of the pad is small compared to the dimensions of the contacting bodies and characteristic radii of curvature of the undeformed surfaces, the contacting surfaces are smooth.When train is driving, the position of the wheelset in relation to the rails varies con- siderably, giving rise to different combinations of the contact areas of the wheel and rail. Even assuming constant axial load the normal voltage will vary considerably because of the differences in the radii of curvature of the contacting surfaces of these zones. Thus, the proposed method allows evaluating the influence of several types of wheel defects on the condition of the rail and the prospects of its use in the upper structure of a railway track on plots with different speed and traffic volumes. Also the results can be used to solve the inverse of the considered problems, for example, when designing high-speed highways, when setting the vehicle speed and axle load, and the solution results are the parameters of the defects, both wheelsets and the rails, in case of which higher require- ments for the safe operation of railways are observed.
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Szychta, Elzbieta, and Leszek Szychta. "Comparative Analysis of Effectiveness of Resistance and Induction Turnout Heating." Energies 13, no. 20 (October 10, 2020): 5262. http://dx.doi.org/10.3390/en13205262.
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Turnouts are key parts of rail roads and are exposed to adverse weather conditions such as snowfall, snow drifts, low temperatures, or sleet. Effective protection assures good turnout function and contributes to rail traffic efficiency and safety. Presently, resistance heating (RH) is the most common system of turnout heating in Europe. In this study, we attempted to implement energy-saving induction heating (IH) in order to cut costs of operation and electricity. A turnout heating test stand, including a stock-rail and a switch-rail, was executed in a climatic chamber. Air temperature was constant at the time of heating. Active power received by both the systems was identical for any measurement (450 W). Test results enabled an assessment of switch-rail position and variations of climatic chamber air temperature on growth of turnout temperatures. Effects of heating type on correct lubrication of the slide plate surface were compared. Dynamics of heating variations and their impact on effectiveness of snow or ice removal were defined for both heating systems. Turnout’s readiness for switch-rail shifting and lubrication conditions of turnout’s moving parts were compared. An in-depth comparative analysis of efficiency of RH and IH turnout heating was undertaken in the conclusion.
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Galay, Marina, and Eduard Sidorov. "Increasing the operational stability of running surfaces of aluminothermiс welded rail joints by hot grinding." MATEC Web of Conferences 216 (2018): 01004. http://dx.doi.org/10.1051/matecconf/201821601004.
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Welded joints have traditionally been a weak point in a design of continuous welded rail (CWR) tracks. Grinding can be used as a resource-saving technology. The purpose of this paper is to study the grinding technology for welded rail joints at different temperatures. The temperature in the weld grinding zone varied from 560 to 850 °С. Using methods of microstructural analysis and hardness measurement, it has been established that different temperature conditions for weld grinding lead to the creation of non-identical mechanical properties of metal and a surface structure of the rail head in the weld zone. As a result of the research, an optimum temperature range, 600 ... 560 °C, was determined. This range is recommended for grinding aluminothermic welded joints.
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Tarabrin, V. F. "COMPARISON OF CHARACTERISTICS OF SEARCHING SYSTEMS OF MOBILE MEANS OF RAILS OF RAIL DEFECTOSCOPY." Kontrol'. Diagnostika, no. 268 (October 2020): 40–48. http://dx.doi.org/10.14489/td.2020.10.pp.040-048.
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The characteristics of wheel-type search systems and sliding systems used for ultrasonic rail monitoring are considered, and their comparison is performed. It is shown that the use of a wheel-type system, the acoustic path of which contains a liquid medium with an increased propagation time of ultrasonic vibrations, limits the control speed to 60 km/h. It is noted that when passing a wheel-type search system of curved sections of track and rails with lateral wear, a change in the direction of propagation of the ultrasonic beam is observed due to a change in the tilt of the wheel relative to the rolling surface of the rail head, which reduces the reliability of detection of rail defects. The disadvantages of the wheel system also include a complex design, low maintainability, poor protection when operating at low temperatures and mechanical stresses, limitations on the ability to operate at high speeds, complicated alignment and, in general, the complexity of maintenance. The characteristics of the retrieval sliding system developed by the specialists of JSC Firma TVEMA are given that provide detection of rail defects with high reliability, operate at low temperatures, and realize a control speed of up to 140 km/h, including in curved sections of the track. The advantages of the proposed non-contact magnetic centering system of the search system, excluding mechanical contact with the rail and the dependence of the centering accuracy on the state of the working face of the rail head, providing unhindered passage of turnouts, including without reducing the speed of control, are presented.
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Tarabrin, V. F. "COMPARISON OF CHARACTERISTICS OF SEARCHING SYSTEMS OF MOBILE MEANS OF RAILS OF RAIL DEFECTOSCOPY." Kontrol'. Diagnostika, no. 268 (October 2020): 40–48. http://dx.doi.org/10.14489/td.2020.10.pp.040-048.
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The characteristics of wheel-type search systems and sliding systems used for ultrasonic rail monitoring are considered, and their comparison is performed. It is shown that the use of a wheel-type system, the acoustic path of which contains a liquid medium with an increased propagation time of ultrasonic vibrations, limits the control speed to 60 km/h. It is noted that when passing a wheel-type search system of curved sections of track and rails with lateral wear, a change in the direction of propagation of the ultrasonic beam is observed due to a change in the tilt of the wheel relative to the rolling surface of the rail head, which reduces the reliability of detection of rail defects. The disadvantages of the wheel system also include a complex design, low maintainability, poor protection when operating at low temperatures and mechanical stresses, limitations on the ability to operate at high speeds, complicated alignment and, in general, the complexity of maintenance. The characteristics of the retrieval sliding system developed by the specialists of JSC Firma TVEMA are given that provide detection of rail defects with high reliability, operate at low temperatures, and realize a control speed of up to 140 km/h, including in curved sections of the track. The advantages of the proposed non-contact magnetic centering system of the search system, excluding mechanical contact with the rail and the dependence of the centering accuracy on the state of the working face of the rail head, providing unhindered passage of turnouts, including without reducing the speed of control, are presented.
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Moon, Abhijeet, and R. Balasubramaniam. "Determination of Hydrogen Diffusivity in Rail Steels by Sub-Scale Microhardness Profiling Technique." Defect and Diffusion Forum 293 (August 2009): 41–45. http://dx.doi.org/10.4028/www.scientific.net/ddf.293.41.
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Hydrogen diffusivity was estimated in three different eutectoid rail steels (C-Mn, Cu-Mo and Ni-Cu-Cr) at ambient temperatures using the technique of sub-surface microhardness profiling after cathodic hydrogen charging in 0.5mol/l sulphuric acid at a current density of 0.1A/cm2 for 24 hours. The increase in the concentration of hydrogen at a certain depth below the surface was related to the microhardness increase at this location as compared to the bulk value. The procedure used to obtain the diffusion coefficient of hydrogen from the microhardness profiles is discussed. The hydrogen diffusivity values in all of the rail steels were found to be similar (of the order of 10-13m2/sec). The estimated hydrogen diffusivity in the rail steel was lower than in pure iron (10-8m2/sec). Possible reasons for the difference are discussed.
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MA, Lei, Wenjian WANG, Jun GUO, and Qiyue LIU. "Study on Wear and Fatigue Performance of Two Types of High-Speed Railway Wheel Materials at Different Ambient Temperatures." Materials 13, no. 5 (March 5, 2020): 1152. http://dx.doi.org/10.3390/ma13051152.
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The wear and fatigue behaviors of two newly developed types of high-speed railway wheel materials (named D1 and D2) were studied using the WR-1 wheel/rail rolling–sliding wear simulation device at high temperature (50 °C), room temperature (20 °C), and low temperature (−30 °C). The results showed that wear loss, surface hardening, and fatigue damage of the wheel and rail materials at high temperature (50 °C) and low temperature (−30 °C) were greater than at room temperature, showing the highest values at low temperature. With high Si and V content refining the pearlite lamellar spacing, D2 presented better resistance to wear and fatigue than D1. Generally, D2 wheel material appears more suitable for high-speed railway wheels.
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Tokmakova, E. N., Ivan Perkov, Pavel Ivanov, and Konstantin Zagranichek. "Development of rails of a new category for use in particularly harsh operating conditions." RUSSIAN RAILWAY SCIENCE JOURNAL 81, no. 4 (October 20, 2022): 339–46. http://dx.doi.org/10.21780/2223-9731-2022-81-4-339-346.
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Introduction. In the conditions of an annual increase in load stress on the roads of the Eastern Polygon, an effective technical solution to the problem of an increased number of rolling stock derailments due to rail breakage is the creation of rails for cold climate conditions with increased hardness to increase wear resistance and contact endurance with simultaneously high values of impact strength. Such a set of properties can be achieved by using separate heating for quenching and cooling with a quenching medium with a high cooling capacity. Rails manufactured using this technology will belong to a new category. In this regard, the purpose of this work was to create a new category of rails for their use in particularly harsh operating conditions.Materials and methods. In this paper the effect of separate induction heating before differentiated quenching with compressed air of controlled humidity on the microstructure and mechanical properties (hardness, mechanical properties during tensile and impact tests, endurance limit, cyclic crack resistance) of rails of type R65 was investigated.The results of the study. A comparative analysis of the results obtained with similar indicators for rails of the DT350, DT350NN and DT370IK categories according to GOST R 51685-2013 was carried out. Studies of the chemical composition, mechanical properties, hardness on the rolling surface of the rail head and cross-section, as well as the microstructure of the rails of the experimental batch showed compliance with the requirements of GOST R 51685-2013 for rails of categories DT350, DT370IK, DT350NN.Discussion and conclusion. It is shown that as a result of the application of differentiated thermal hardening of the rail using compressed air of controlled humidity as a quenching medium, a new category of DTO350NN rails was obtained, characterized by a favorable combination of strength properties, plasticity characteristics and brittle fracture resistance indicators. Rails of the new category can be recommended for use in particularly severe operating conditions (in curved sections of the track of a small radius at low temperatures), including on the roads of the Eastern Polygon.
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Stojanović, Željko, Božidar Matijević, Sanja Stanisavljev, and Spasoje Erić. "Investigation of fractures mechanisms of railway axles." Zastita materijala 62, no. 1 (2021): 51–62. http://dx.doi.org/10.5937/zasmat2101051s.
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The paper gives a systematic overview of literature sources who consider impacts critical damage of mechanical, corrosive and thermal nature which may occur on railway axles during operation and which may be the causes of their fracture. The results of the research of the mechanisms that cause cracks, crack propagation and final fracture of the railway vehicle axle, such as material fatigue and the appearance of localized notches caused by paint (coating) separation, damage from ballast impact and pitting corrosion are presented. The influence of high temperatures and overheating on the axles was analyzed and an excerpt from the research published in one research report was given. Some significant suggestions for optimizing the design of the axles are highlighted which would take into account the analysis of time-varying axle stresses, stress spectrum in operation, axle tolerance to damage and the existence of residual surface stresses. The reliefs of the fracture surfaces of the axle after the railway incidents and the derailment of the rail vehicle from the rails are presented and explained.
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Ding, Siyuan, Meixian Zhang, Yiding Ou, and Lei Ma. "Study on the Influence of Friction and Wear Properties of High-Speed Rail Brake Materials under Humidity Environment and Temperature Conditions." Materials 16, no. 4 (February 15, 2023): 1610. http://dx.doi.org/10.3390/ma16041610.
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A multi-functional friction and wear testing machine was used to test the pin disk wear of high-speed railway brake friction material under different disk temperatures (20 °C, 100 °C, and 200 °C) and different ambient humidities (55%, 95%). The test results show that the change in the disk temperature and different ambient humidities have significant effects on the frictional wear performance of the high-speed railway brake material. Under the conditions of 20 °C, 100 °C and 200 °C, the instantaneous friction coefficient and wear rate of the brake material decreased as the ambient humidity increased. The different ambient humidity caused severe surface damage to the brake materials, but the damage mechanisms were dramatically different. At constant temperature, the higher the ambient humidity, the lower the maximum equilibrium temperature of the disc.
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Nurutdinov, Azamat, and Klara Yamaletdinova. "Evaluation of sorbents’ oil capacity properties at various temperatures." Bulletin of scientific research results, no. 1-2 (July 17, 2017): 16–22. http://dx.doi.org/10.20295/2223-9987-2017-1-2-16-22.
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Objective: The oil capacity properties of the sorbents used for oil collection are qualitatively estimated at various temperatures. One of the factors securing sustained rail transport development is taking measures to prevent and eliminate the accidental spillages of dangerous goods including oil and oil products. Such accidents occur causing significant environmental contamination. Methods: Using sorbents for containment and elimination of such accidents has a good track record. Their properties have not been, however, sufficiently investigated at various temperatures. The sorbents’ oil capacity is determined by the standard gravimetric method using the difference between the weight of a sorbent impregnated with oil product and that of a pure sorbent based on 1 g (kg) of a pure sorbent. Results: Oil viscosity grows as the temperature goes down. The research findings show higher sorbents’ oil capacity figures caused by a changed oil recovery mechanism due to its higher viscosity: at a low or moderate viscosity, oil sorbs inside the sorbent volume, whereas at a high viscosity (above 200 mm2/s) sorbent surface adhesion occurs. Practical importance: A qualitative analysis of sorbents is important for ensuring environmental safety.
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Gudipati, M., and M. Greiner. "Computational fluid dynamics simulations of fuel cladding and basket surface temperatures in multipurpose canister rail cask during normal transport." Packaging, Transport, Storage & Security of Radioactive Material 19, no. 3 (September 2008): 173–79. http://dx.doi.org/10.1179/174651008x309088.
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Kim, Dong-wook, Jung-Hyun Woo, and Kyoung-Su Park. "Investigation of the thermal effect of a tubular permanent magnet actuator with a water cooling channel for active lateral suspension of a high-speed train." Advances in Mechanical Engineering 11, no. 3 (March 2019): 168781401881966. http://dx.doi.org/10.1177/1687814018819666.
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Worldwide, high-speed rail is becoming an increasingly popular and efficient means of transport. However, increasing the speed of a train leads to major reductions in stability and ride comfort. Here, we develop a tubular permanent magnet actuator to overcome these problems. To increase actuator thrust, the electromagnetic circuit requires a high current and, thus, becomes hot. We use a water cooling system with 12 straight copper channels to reduce the temperature. We calculate heat transfer coefficients using empirical convection correlations between laminar flow in the channels and experimental results. The predicted, tube surface temperatures correlated well with the experimental data. We evaluated the effects of flow rate and initial water temperature on various design parameters. The cooling system allowed application of a current greater than 100 A, developing a thrust force of over 8000 N. Thus, the system was robust under harsh operating conditions. We measured the thrust and cogging forces and the performance of the water cooling system in terms of the maximum acceptable temperature. The thrust was high and the cogging torque was low, greatly reducing lateral vibration; the temperature remained below the acceptable maximum.
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Flanagan, Paul Xavier, Rezaul Mahmood, Natalie A. Umphlett, Erin Haacker, C. Ray, William Sorensen, Martha Shulski, Crystal J. Stiles, David Pearson, and Paul Fajman. "A Hydrometeorological Assessment of the Historic 2019 Flood of Nebraska, Iowa, and South Dakota." Bulletin of the American Meteorological Society 101, no. 6 (June 1, 2020): E817—E829. http://dx.doi.org/10.1175/bams-d-19-0101.1.
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Abstract During early 2019, a series of events set the stage for devastating floods in eastern Nebraska, western Iowa, and southeastern South Dakota. When the floodwaters hit, dams and levees failed, cutting off towns while destroying roads, bridges, and rail lines, further exacerbating the crisis. Lives were lost and thousands of cattle were stranded. Estimates indicate that the cost of the flooding has topped $3 billion as of August 2019, with this number expected to rise. After a warm and wet start to winter, eastern Nebraska, western Iowa, and southeastern South Dakota endured anomalously low temperatures and record-breaking snowfall. By March 2019, rivers were frozen, frost depths were 60–90 cm, and the water equivalent of the snowpack was 30–100 mm. With these conditions in place, a record-breaking surface cyclone rapidly developed in Colorado and moved eastward, producing heavy rain toward the east and blizzard conditions toward the west. In areas of eastern Nebraska, western Iowa, and southeastern South Dakota, rapid melting of the snowpack due to this rain-on-snow event quickly led to excessive runoff that overwhelmed rivers and streams. These conditions brought the region to a standstill. In this paper, we provide an analysis of the antecedent conditions in eastern Nebraska, western Iowa, and southeastern South Dakota and the development of the surface cyclone that triggered the historic flooding, along with a look into the forecast and communication of flood impacts prior to the flood. The study used multiple datasets, including in situ observations and reanalysis data. Understanding the events that led to the flooding could aid in future forecasting efforts.
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Kusaka, J., M. Sueoka, K. Takada, Y. Ohga, T. Nagasaki, and Y. Daisho. "A basic study on a urea-selective catalytic reduction system for a medium-duty diesel engine." International Journal of Engine Research 6, no. 1 (February 1, 2005): 11–19. http://dx.doi.org/10.1243/146808705x7310.
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NOx conversion performance of a urea-selective catalytic reduction (SCR) system comprising V2O5/TiO2 catalyst under steady state operating conditions of an 8-litre, common-rail turbo direct injection (TDI) diesel engine was investigated. It was shown that the urea-SCR system achieves 70–90 per cent NOx conversion under medium and high load conditions at 1440 r/min and that NOx conversion is low under low load conditions because of the low catalyst temperatures and the NO/NO2 ratio being higher than unity. It was also shown that NOx conversion exceeds 90 per cent when the catalyst temperature is higher than 530 K. To investigate the details of the chemistry and thermofluid dynamics within the urea-SCR system, a computational fluid dynamics (CFD) code that incorporates detailed surface chemistry was developed based on the modified subroutines of CHEMKIN-II. The spatial variations of chemical species including NO and NH3 in a thin catalyst channel was calculated using the model. The calculated result of NO conversion showed relatively good agreement with experimental results.
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Yuan, Bei, Dunming Liao, Wenming Jiang, Han Deng, and Guangyu Li. "Study on Friction and Wear Properties and Mechanism at Different Temperatures of Friction Stir Lap Welding Joint of SiCp/ZL101 and ZL101." Metals 13, no. 1 (December 20, 2022): 3. http://dx.doi.org/10.3390/met13010003.
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In order to achieve the goal of lightening the braking system of urban rail trains, SiCp/ZL101 and ZL101 plates were welded by friction stir lap welding (FSLW) to prepare a new type of brake disc material. The friction and wear properties of the friction-stir-processed composite material were studied at different temperatures (30 °C, 100 °C, 150 °C, 200 °C, 250 °C, 300 °C) to provide a theoretical basis for the evaluation of braking performance. The experimental results showed that the sliding friction processes at each temperature were relatively stable, the friction coefficients did not vary much and the average friction coefficients changed slightly, stabilizing at about 0.4. The wear extent and the depth of wear scars increased with the increase in the temperature, reaching the highest at 150 °C and then began to decrease. At room temperature, the wear forms were mainly oxidative wear and abrasive wear; as the temperature rose, under the cyclic shearing action of the grinding ball, the abrasive debris fell off under the expansion of fatigue cracks and fatigue wear was the main form at this stage. When the temperature reached 200 °C, it began to show the characteristics of adhesive wear; after 250 °C, due to the gradual formation of a mechanical mixed layer containing more SiC particles and oxides on the wear surface, it exhibited high-temperature lubrication characteristics, and the wear extent was equivalent to 35% of the wear extent at normal temperature, indicating that the composite material had good high-temperature friction and wear properties.
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Schieber, C., M. Hettig, M. F. Zaeh, and C. Heinzel. "3D modeling and simulation of thermal effects during profile grinding." Production Engineering 14, no. 5-6 (September 15, 2020): 655–65. http://dx.doi.org/10.1007/s11740-020-00983-8.
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AbstractA new heat transfer model for profile grinding was developed to analyze distortions caused by residual tensile stresses in linear guide rails. The simulative analysis of the thermal effects caused by a non-uniform heat source on the surface using the finite element method depends on an accurate representation of the locally variable contact area. The complexity of the V-groove profile disqualifies a 2-dimensional simulation approches so far used in the literature. This paper focuses on the redefinition of these mathematical relationships of the process parameters and the resulting heat flux. The heat flux model is adapted to the geometry of the workpiece depending on the grinding parameters and approximating the V-groove of a linear guide rail. This 3-dimensional modeling allows a better understanding of the thermo-metallurgical effects that occur during the grinding process. Furthermore, the calculation of the internal stresses induced into the workpiece material through the grinding process is possible. The simulation model results in a generally valid model for the analysis of distortions. In order to confirm the validity of the new heat flux profile, a comparison of the different finite element simulation results was made and experiments under wet grinding conditions were conducted. The results show that the newly developed grinding process model allows a more accurate prediction of workpiece distortion caused by grinding forces and temperatures. This research also offers a new approach to a method based on a 2-dimensional implementation developed in the literature for predicting the distortions of linear guide rails and a derivation of possible simulation-based compensation strategies.
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Mazilu, Traian, and Mihai Cornel Leu. "On the Modelling of Rail Joint." Materials Science Forum 957 (June 2019): 33–42. http://dx.doi.org/10.4028/www.scientific.net/msf.957.33.
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Jointed track is still used to build the secondary lines where the maximum speed does not exceed 100-120 km/h. Jointed track construction is based by the fact that the rails are joined end-to-end via the rail joints in order to assure the continuity of the rolling surface of the rails. The rails are jointed using two metal joint bars (fishplates) bolted to the ends of adjoining rails. The rail joints are featured with small gaps to allow the thermic expansion of the rails when the environmental temperature is higher than that during the fitting. In this paper, an analytical model for the rail joint considering the influence of the joint gap is presented and analysed. The model consists of three Euler-Bernoulli beams, two for the rail ends of the rail joint and the third beam for the two joint bars, connected to the rail ends by a Winkler layer. The concept of weakness of the rail joint (rail joint deflection/continuous rail deflection) is introduced and used to analyse the static behaviour of three types of rail joints used at CFR (Romanian Railways). The influence of the joint bars length and bending stiffness, and the influence of the joint gap length upon the rail joint weakness is pointed out.
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Dumitriu, Mădălina. "Numerical Analysis of the Vertical Bogie Accelerations at Failure of the Damper in the Primary Suspension of the Railway Vehicle." Materials Science Forum 957 (June 2019): 43–52. http://dx.doi.org/10.4028/www.scientific.net/msf.957.43.
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Jointed track is still used to build the secondary lines where the maximum speed does not exceed 100-120 km/h. Jointed track construction is based by the fact that the rails are joined end-to-end via the rail joints in order to assure the continuity of the rolling surface of the rails. The rails are jointed using two metal joint bars (fishplates) bolted to the ends of adjoining rails. The rail joints are featured with small gaps to allow the thermic expansion of the rails when the environmental temperature is higher than that during the fitting. In this paper, an analytical model for the rail joint considering the influence of the joint gap is presented and analysed. The model consists of three Euler-Bernoulli beams, two for the rail ends of the rail joint and the third beam for the two joint bars, connected to the rail ends by a Winkler layer. The concept of weakness of the rail joint (rail joint deflection/continuous rail deflection) is introduced and used to analyse the static behaviour of three types of rail joints used at CFR (Romanian Railways). The influence of the joint bars length and bending stiffness, and the influence of the joint gap length upon the rail joint weakness is pointed out.
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Kowalik, Paweł, and Mariusz Fabijański. "Effect of biodegradable oil use on the mechanical properties of plastics used in the railway surface (Odziaływanie biodegradowalnego oleju na właściwości mechaniczne tworzyw sztucznych stosowanych w nawierzchni kolejowej)." WUT Journal of Transportation Engineering 128 (March 1, 2020): 81–88. http://dx.doi.org/10.5604/01.3001.0014.0906.
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The purpose of this study is to present the requirements, methodology, and results of research on the impact of biodegradable oil on plastic components used in the construction of a railway turnout. Briefly discussed are what railroad turnouts are, how they work, and what problems occur with substances used for their lubrication. They have an impact on the mechanical properties and durability of products made of polymeric materials. These types of materials absorb various kinds of chemicals, to a greater or lesser degree, and this affects their properties. For the tests, we used a universal lubrication oil with biodegradable properties, which is its most significant advantage. However, it may not cause deterioration of the turnout operation and change the properties of materials used for its construction. These types of oils require more frequent applications on cooperating components. We used the two most popular polymer materials. The first is high-density polyethylene (HDPE), used to make all kinds of rail spacers, dowels for fixing rails, sleeves, etc. The second, polyurethane (PUR) is most commonly used for rail pads of various shapes. The methodology and results of testing the impact of a lubricant (biodegradable oil) on the change of mechanical properties such as strength and hardness are presented. The tests were carried out at various temperatures; the time of exposure to oil was seven days; the results were referred to samples conditioned under standard conditions. The tests carried out on the impact of the biodegradable lubricant on polymeric materials (HDPE and PUR) showed little effect on the change of strength parameters of these materials. Celem niniejszego opracowania jest przedstawienie wymagań, metodyki oraz wyników badań oddziałania biodegradowalnego oleju na elementy z tworzyw sztucznych stosownych w budo-wie rozjazdu kolejowego. Krótko omówiono czym są rozjazdy kolejowe i jak działają oraz jakie występują problemy z substancjami używanymi do ich smarowania, które nie pozostają bez wpływu na właściwości mechaniczne i trwałość wyrobów z materiałów polimerowych. Materiały tego typu wchłaniają różnego rodzaju substancje chemiczne w większym lub mniejszym stopniu, a to ma wpływ na ich właściwości. Do badań został wykorzystany uniwersalny olej do smarowania o biodegradowalnych właściwościach, co jest jego największą zaletą. Jednak nie może on powodować pogorszenia pracy rozjazdu oraz zmieniać właściwości materiałów użytych do jego budowy. Tego typu oleje wymagają częstszego aplikowania na elementy współpracujące ze sobą. W pracy wykorzystano dwa najbardziej popularne materiały polimerowe. Pierw-szy to polietylen o dużej gęstości (HDPE), z którego wykonuje się wszelkiego rodzaju przekładki podszynowe, dyble do mocowania szyn, tuleje, itp. Drugi to poliuretan (PUR) stosowany najczęściej na przekładki podszynowe o różnym kształcie. Zaprezentowano metodykę i wyniki ba-dań oddziaływania środka smarnego (biodegradowalnego oleju) na zmianę właściwości mechanicznych takich jak wytrzymałość oraz twardość. Badania zostały przeprowadzone w różnych temperaturach, a czas ekspozycji na olej wynosił 7 dób, wyniki odniesiono do próbek klimatyzowanych w standardowych warunkach. Przeprowadzone badania oddziaływania biodegradowalnego środka smarnego na tworzywa polimerowe (HDPE i PUR), wykazały niewielki wpływ na zmianę parametrów wytrzymałościowych tych materiałów.
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Viesca, JL, S. González-Cachón, A. García, R. González, and A. Hernández Battez. "Tribological behaviour of microalloyed and conventional C–Mn rail steels in a pure sliding condition." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 232, no. 9 (March 14, 2018): 2201–14. http://dx.doi.org/10.1177/0954409718765063.
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This paper compares the tribological behaviour of microalloyed rail steel with conventional C–Mn rail steel under different test conditions (load, temperature and humidity). Pin-on-disc tribological tests were performed inside a climate chamber under different loads (20, 30 and 40 N), relative humidity (15, 55 and 70%) and temperatures (20 and 40 ℃). After the friction and wear tests, the worn surfaces were analysed using both confocal and scanning electron microscopies. The results obtained show that the use of microalloyed steel in railway applications under severe conditions (high loads and humidity) could lead to increased service life of the rails and could extend the time between maintenance operations.
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Sarychev, V. D., S. G. Molotkov, V. E. Kormyshev, S. A. Nevskii, and E. V. Polevoi. "Simulation of differentiated thermal processing of railway rails by compressed air." Izvestiya. Ferrous Metallurgy 63, no. 11-12 (January 3, 2021): 907–14. http://dx.doi.org/10.17073/0368-0797-2020-11-12-907-914.
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Mathematical modeling of differentiated thermal processing of railway rails with air has been carried out. At the first stage, onedimensional heat conduction problem with boundary conditions of the third kind was solved analytically and numerically. The obtained temperature distributions at the surface of the rail head and at a depth of 20 mm from the rolling surface were compared with experimental data. As a result, value of the coefficients of heat transfer and thermal conductivity of rail steel was determined. At the second stage, mathematical model of temperature distribution in a rail template was created in conditions of forced cooling and subsequent cooling under natural convection. The proposed mathematical model is based on the Navier-Stokes and convective thermal conductivity equations for the quenching medium and thermal conductivity equation for rail steel. On the rail – air boundary, condition of heat flow continuity was set. In conditions of spontaneous cooling, change in temperature field was simulated by heat conduction equation with conditions of the third kind. Analytical solution of one-dimensional heat conduction equation has shown that calculated temperature values differ from the experimental data by 10 %. When cooling duration is more than 30 s, change of pace of temperature versus time curves occurs, which is associated with change in cooling mechanisms. Results of numerical analysis confirm this assumption. Analysis of the two-dimensional model of rail cooling by the finite element method has shown that at the initial stage of cooling, surface temperature of the rail head decreases sharply both along the central axis and along the fillet. When cooling duration is over 100 s, temperature stabilizes to 307 K. In the central zones of the rail head, cooling process is slower than in the surface ones. After forced cooling is stopped, heating of the surface layers is observed, due to change in heat flow direction from the central zones to the surface of the rail head, and then cooling occurs at speeds significantly lower than at the first stage. The obtained results can be used to correct differential hardening modes.
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Sarychev, V. D., S. G. Molotkov, V. E. Kormyshev, S. A. Nevskii, and E. V. Polevoi. "Simulation of differentiated thermal processing of railway rails by compressed air." Izvestiya. Ferrous Metallurgy 63, no. 11-12 (January 3, 2021): 907–14. http://dx.doi.org/10.17073/0368-0797-2020-11-12-907-914.
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Mathematical modeling of differentiated thermal processing of railway rails with air has been carried out. At the first stage, onedimensional heat conduction problem with boundary conditions of the third kind was solved analytically and numerically. The obtained temperature distributions at the surface of the rail head and at a depth of 20 mm from the rolling surface were compared with experimental data. As a result, value of the coefficients of heat transfer and thermal conductivity of rail steel was determined. At the second stage, mathematical model of temperature distribution in a rail template was created in conditions of forced cooling and subsequent cooling under natural convection. The proposed mathematical model is based on the Navier-Stokes and convective thermal conductivity equations for the quenching medium and thermal conductivity equation for rail steel. On the rail – air boundary, condition of heat flow continuity was set. In conditions of spontaneous cooling, change in temperature field was simulated by heat conduction equation with conditions of the third kind. Analytical solution of one-dimensional heat conduction equation has shown that calculated temperature values differ from the experimental data by 10 %. When cooling duration is more than 30 s, change of pace of temperature versus time curves occurs, which is associated with change in cooling mechanisms. Results of numerical analysis confirm this assumption. Analysis of the two-dimensional model of rail cooling by the finite element method has shown that at the initial stage of cooling, surface temperature of the rail head decreases sharply both along the central axis and along the fillet. When cooling duration is over 100 s, temperature stabilizes to 307 K. In the central zones of the rail head, cooling process is slower than in the surface ones. After forced cooling is stopped, heating of the surface layers is observed, due to change in heat flow direction from the central zones to the surface of the rail head, and then cooling occurs at speeds significantly lower than at the first stage. The obtained results can be used to correct differential hardening modes.
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Kukulski, Jacek, Piotr Gołębiowski, Jacek Makowski, Ilona Jacyna-Gołda, and Jolanta Żak. "Effective Method for Diagnosing Continuous Welded Track Condition Based on Experimental Research." Energies 14, no. 10 (May 17, 2021): 2889. http://dx.doi.org/10.3390/en14102889.
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The correct operation of the continuous welded track requires diagnosing its condition and preparation of track metrics requiring measurements of displacements of rail under operation. This is required as there are additional thermal stresses in the rails with values depending on the temperature changes of the rails. Therefore, the climatic conditions are important. This paper presents the original effective analytical method for diagnosing the condition of continuous welded track based on experimental research. The method allows for an appropriate repair or maintenance recommendation. In the experimental research, the authors considered track diagnostic conditions for two conditions: track under load and track without load. This paper presents empirical formulas for calculating rail temperature and longitudinal force based on ambient temperature, developed from long-term measurements. The formulas were developed for a track located on a straight section—both for a rail loaded and unloaded with a passing train under the following conditions: 60E1 rail, not on an engineering structure, conventional surface, wooden sleepers and very high train traffic load. The obtained results in the value of the correlation coefficient R2 ≥ 0.995 attest to very high accuracy of the calculations performed with the method proposed by the authors.
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Nakano, Teppei, Antoine Pacco, Shota Iwahata, Efrain Altamirano, and Akihisa Iwasaki. "(Digital Presentation) A Novel Method For Molybdenum Etching Using a Combination of Surface Oxidation By Ozone-Gas-Bake and Wet Selective Removal for Future Semiconductor Devices." ECS Meeting Abstracts MA2022-01, no. 28 (July 7, 2022): 1261. http://dx.doi.org/10.1149/ma2022-01281261mtgabs.
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1. Introduction Alternative metals are being researched to mitigate the resistivity of the metal wiring at 3 nm technology node and beyond. A performance index or figure of merit (FOM) calculated by multiplying the resistivity and the electron mean free path of the bulk metal has been defined to allow the selection of candidate metals to reduce the resistance of fine wiring. Mo (6.0) is a good candidate compared to the conventional metals such as Cu (6.7) and W (8.2) [1-3]. Commodity wet chemistries, e.g. SC-1 or mixed acids like, Phosphoric:Acetic:Nitric-acid (PAN) are not suitable for wet recess etch of Mo since they increase its surface roughness too much. The model for the increase in roughness has been reported to be due to the presence of grain boundaries on the Mo surface, where preferential "oxidation-dissolution" reactions occur simultaneously in the chemical solution [4,5]. To minimize the roughness, a new cyclic process of dry oxidation and wet etching is developed so that oxidation and etching reactions are separated. In the oxidation step, a homogeneous oxide layer is formed by baking in ozone (O3) gas, then it is selectively etched by subsequent wet chemistry which doesn’t contain any oxidant [6]. In this paper, we report the development of this molybdenum recess process with a higher baking temperature to increase the recess depths, targeting application of buried power rail in logic and word line recess in 3D NAND memory. 2. Experimental Sample: 50 nm Mo films were deposited by Plasma Vapor Deposition on a 100 nm SiO2 film. After metal deposition, the wafers were annealed for 20 minutes at 420°C in pure N2 gas. Etching process: oxidation process is performed in an O3 gas chamber on a single wafer cleaning tool. Bake plate in the O3 gas chamber was heated to 180-290°C. O3 concentration was 100 g/m3 and gas flow rate was 18 L/min. The subsequent wet etch process was performed in wet process chamber on the same tool. 29% NH4OH was mixed with ultrapure water in a 1:8 or 1:100 volume ratio at RT or 70°C. Characterization: the recess amounts of metallic Mo and MoOx thicknesses were measured by sheet resistance measurements and mass measurements of 300 mm wafers. Roughness was measured by Atomic Force Microscope, XSEM was used to validate the above. The polycrystallinity of MoOx was analyzed by Grazing Incidence X-ray Diffraction. 3. Results/Discussion Mo thickness decreases as the number of oxidation and etching cycles increases, and the recess amount per cycle was 6 nm at 290°C (Fig. 1). The recess amount per 3 cycles increased as bake temperature increases (Fig. 2). Rq increased from 0.4 nm to 2.8 nm at bake temperatures ≥ 250°C (Fig. 3). XSEM showed that the cause of the surface roughness is residual MoOx (Fig. 4). XRD showed that the MoOx changes significantly at bake temperatures ≥ 250°C since other than the metallic crystalline Mo peak at 2θ = 40° were detected, which suggests that polycrystalline MoOx is formed at high temperature (Fig. 5). The formation of a polycrystalline MoOx could be the cause of the surface roughness because these MoOx are tough to dissolve and therefore the surface would not be recessed evenly. On the other hand, the residual MoOx was etched by NH4OH in a 1:8 ratio at 70°C and Rq was reduced to 0.38 nm after a cyclic process using a 290°C bake with O3 (Fig. 3, 4). 4. Conclusion A novel etching method using a combination of “ozone-gas-bake” and “wet selective removal” was developed to overcome the roughness increase during etching of Mo observed with commodity wet chemistries. This method demonstrates good controllability of Mo etching amount by changing the number of cycles without roughening the surface. The surface roughness increased at bake temperatures ≥ 250°C due to the formation of polycrystalline MoOx that could not be removed with the conventional NH4OH solution, but this was mitigated by increasing the temperature of the subsequent NH4OH oxide dissolution step. This new process is expected to be used to recess Mo in logic and memory devices for next generation applications. References [1] D. Gall, J. Appl. Phys. 127, 050901. 2020. [2] D. Gall, J. Appl. Phys. 119, 085101. 2016. [3] C. Adelmann, et al., Proc. IEEE IITC 2018, pp.: 154-156 [4] A. Zambova, et al., J. Electrochem. Soc., 139, 9, 2470. 1992. [5] A. Pacco, et al., Solid State Phenomena, 2021, 314, pp. 295-301. [6] A.Pacco, et al., IITC 2021. Figure 1
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TANIMOTO, Hiraku, and Hua CHEN. "2A22 Influence of Surface Roughness and Temperature on the Adhesion of Wheel and Rail in Wet Conditions(Boundary)." Proceedings of International Symposium on Seed-up and Service Technology for Railway and Maglev Systems : STECH 2015 (2015): _2A22–1_—_2A22–8_. http://dx.doi.org/10.1299/jsmestech.2015._2a22-1_.
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Prokof’iev, O., R. Gubatyuk, S. Rymar, V. Sydorets, and Valery Kostin. "Inductor for Uniform Bulk Heat Treatment of Welded Butt Joints of Railway Rails." Solid State Phenomena 313 (January 2021): 72–81. http://dx.doi.org/10.4028/www.scientific.net/ssp.313.72.
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To improve the structure of metal in welded butt joints of railway rails produced by flash-butt welding and increase the reliability of butt joints, it is advisable to carry out their induction heat treatment using high-frequency currents. Solving the problem of a uniform bulk heating of weld metal of railway rails in a narrow area during its heat treatment remains an urgent task. The work describes the principle of designing an inductor without magnetic cores for carrying out a uniform bulk heat treatment of welded butt joints of railway rails for realization of favorable phase transformations of metal and normalization of its structure. The principle is based on the physical laws of propagation of electromagnetic fields and electric currents in the inductor and a rail. Based on the carried out investigations, an inductor was designed that has a variable shape along the perimeter of a rail and a variable distance from it, as well as a partial splitting of the inductor busbar for current parallelization, which provides a uniform bulk heating of a rail butt joint. Splitting of the inductor busbar allowed adjusting the propagation of currents in the inductor and a rail in such a way as to avoid overheating of a rail in its particular areas without a significant increase in the distance between the inductor and a rail, and respectively without a significant increase in the reactive power of the “inductor-product” system. The carried out experiments on heating the welded butt joint of a rail by the designed inductor showed the indices of uniformity and rate of its bulk heating, which are acceptable for heat treatment of rails both on the surface as well as in the depth of a rail in a narrow heating zone with providing the required temperature levels.
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Prokof’iev, O., R. Gubatyuk, S. Rymar, V. Sydorets, and Valery Kostin. "Inductor for Uniform Bulk Heat Treatment of Welded Butt Joints of Railway Rails." Solid State Phenomena 313 (January 2021): 72–81. http://dx.doi.org/10.4028/www.scientific.net/ssp.313.72.
Full textAbstract:
To improve the structure of metal in welded butt joints of railway rails produced by flash-butt welding and increase the reliability of butt joints, it is advisable to carry out their induction heat treatment using high-frequency currents. Solving the problem of a uniform bulk heating of weld metal of railway rails in a narrow area during its heat treatment remains an urgent task. The work describes the principle of designing an inductor without magnetic cores for carrying out a uniform bulk heat treatment of welded butt joints of railway rails for realization of favorable phase transformations of metal and normalization of its structure. The principle is based on the physical laws of propagation of electromagnetic fields and electric currents in the inductor and a rail. Based on the carried out investigations, an inductor was designed that has a variable shape along the perimeter of a rail and a variable distance from it, as well as a partial splitting of the inductor busbar for current parallelization, which provides a uniform bulk heating of a rail butt joint. Splitting of the inductor busbar allowed adjusting the propagation of currents in the inductor and a rail in such a way as to avoid overheating of a rail in its particular areas without a significant increase in the distance between the inductor and a rail, and respectively without a significant increase in the reactive power of the “inductor-product” system. The carried out experiments on heating the welded butt joint of a rail by the designed inductor showed the indices of uniformity and rate of its bulk heating, which are acceptable for heat treatment of rails both on the surface as well as in the depth of a rail in a narrow heating zone with providing the required temperature levels.
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Tuschl, Christoph, Beate Oswald-Tranta, and Sven Eck. "Inductive Thermography as Non-Destructive Testing for Railway Rails." Applied Sciences 11, no. 3 (January 22, 2021): 1003. http://dx.doi.org/10.3390/app11031003.
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Inductive thermography is a non-destructive testing method, whereby the specimen is slightly heated with a short heating pulse (0.1–1 s) and the temperature change on the surface is recorded with an infrared (IR) camera. Eddy current is induced by means of high frequency (HF) magnetic field in the surface ‘skin’ of the specimen. Since surface cracks disturb the eddy current distribution and the heat diffusion, they become visible in the IR images. Head checks and squats are specific types of damage in railway rails related to rolling contact fatigue (RCF). Inductive thermography can be excellently used to detect head checks and squats on rails, and the method is also applicable for characterizing individual cracks as well as crack networks. Several rail pieces with head checks, with artificial electrical discharge-machining (EDM)-cuts and with a squat defect were inspected using inductive thermography. Aiming towards rail inspection of the track, 1 m long rail pieces were inspected in two different ways: first via a ‘stop-and-go’ technique, through which their subsequent images are merged together into a panorama image, and secondly via scanning during a continuous movement of the rail. The advantages and disadvantages of both methods are compared and analyzed. Special image processing tools were developed to automatically fully characterize the rail defects (average crack angle, distance between cracks and average crack length) in the recorded IR images. Additionally, finite element simulations were used to investigate the effect of the measurement setup and of the crack parameters, in order to optimize the experiments.
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Zhou, Dongdong, Feng Gao, Junjian Wang, and Ke Xu. "Study of Surface Temperature Distribution for High-Temperature U75V Rail Steel Plates in Rolling Process by Colorimetry Thermometry." Metals 12, no. 5 (May 17, 2022): 860. http://dx.doi.org/10.3390/met12050860.
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Surface temperature is a critical operating parameter that influences the phase transition time and rolling quality of U75V rail steel plates in the rolling process. There is still no extensive online detection system for the surface temperature of rail steel plates due to the hazardous environment, incorrect surface emissivity, and complex backgrounds. In this paper, online surface temperature detection equipment based on multi-spectral photography was built for high-temperature rail steel plates in the rolling processes. Then, the emissivity model for a high-temperature environment, colorimetric thermometry, and noise filtering methods were investigated to improve the accuracy of the temperature detection results of rail steel plates. Finally, the surface temperature of the U75V rail steel plate during three rolling passes could be calculated online point by point, and the greatest error was approximately 0.82% due to the blackbody calibration experiments. The results not only have a positive effect on understanding the temperature declination process of low-alloy rail steel plates during the rolling process, but could also benefit the control of the cooling rate and optimize the rolling model during rolling passes.
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Umanskii, A. A., A. V. Golovatenko, A. S. Simachev, V. V. Dorofeev, and T. N. Oskolkova. "Plasticity and deformation resistance of the alloyed rail steels in rolling temperature interval." Izvestiya. Ferrous Metallurgy 62, no. 6 (June 28, 2019): 452–60. http://dx.doi.org/10.17073/0368-0797-2019-6-452-460.
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On the basis of conducted experimental studies, regularities of the influence of temperature-speed rolling conditions on the plasticity and deformation resistance in the zones of continuously cast billets of alloy rail steels of E76KhF, E76KhSF grades are determined and scientifically substantiated. The results indicate the complex nature of dependence of rail steel E76KhF plasticity on deformation temperature. In particular, for near-surface layers of continuously cast billets, a noticeable decrease in plasticity in the temperature range of 1025 – 1075 °Cwas recorded, which is absent for the layers located in central zone of that billets. Generalization of the results of plasticity studies of various layers of continuously cast rail E76KhF steel billets has shown that absolute values of the plasticity criterion are significantly reduced with the distance from the surface to the central zone. This fact can be explained by a coarse-grained structure and increased concentration of non-metallic inclusions in the central zone of continuously cast billets relative to their surface layers; it was confirmed by the results of metallographic studies. In particular, it was found that the average grains diameter in the surface layer of deformed continuously cast billets is in 1.3 – 2.1 times less compared to the central zone. There was confirmed the presence of significant concentrations of non-deformable inclusions of the silicate type (Al2O3· SiO2 ; FeO·SiO2 ; MnO·SiO2 ), which have most negative influence on steel plasticity while in the surface area such inclusions are absent. On the basis of conducted researches it was established that with increase in deformation temperature of rail steel E76KhSF there is a decrease in resistance to plastic deformation according to the exponential law. In this case, absolute values of the steel deformation resistance are reduced with the distance from the surface to the central zone of continuously cast billets, which is associated with the above illustrated increase in grain size and localization of non-metallic inclusions. The revealed tendency to reduce the deformation resistance from the surface layers to the center of continuously cast billets is maintained regardless to deformation rate, while the absolute values of the deformation resistance increase significantly with the growth of deformation rate from 1 to 10 s–1. Mathematical processing of the obtained experimental data allowed to obtain regression equations that help to predict plastic and deformation properties of alloyed rail steels of E76KhF and E76KhSF grades with a sufficient degree of reliability under the specified rolling conditions and are complex theoretical basis for the development and improvement of new heating modes of billets for rolling and rail rolling schemes. Adequacy of the obtained experimental dependences is confirmed by results of pilot industrial testing of the new mode of railway rails production on the universal rail mill of “EVRAZ ZSMK”.
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Mekis, Eva, Ronald E. Stewart, Julie M. Theriault, Bohdan Kochtubajda, Barrie R. Bonsal, and Zhuo Liu. "Near-0 °C surface temperature and precipitation type patterns across Canada." Hydrology and Earth System Sciences 24, no. 4 (April 9, 2020): 1741–61. http://dx.doi.org/10.5194/hess-24-1741-2020.
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Abstract. The 0 ∘C temperature threshold is critical for many meteorological and hydrological processes driven by melting and freezing in the atmosphere, surface, and sub-surface and by the associated precipitation varying between rain, freezing rain, wet snow, and snow. This threshold is especially important in cold regions such as Canada, because it is linked with freeze–thaw, snowmelt, and permafrost. This study develops a Canada-wide perspective on near-0 ∘C conditions using hourly surface temperature and precipitation type observations from 92 climate stations for the period from 1981 to 2011. In addition, nine stations from various climatic regions are selected for further analysis. Near-0 ∘C conditions are defined as periods when the surface temperature is between −2 and 2 ∘C. Near-0 ∘C conditions occur often across all regions of the country, although the annual number of days and hours and the duration of these events varies dramatically. Various types of precipitation (e.g., rain, freezing rain, wet snow, and ice pellets) sometimes occur with these temperatures. Near-0 ∘C conditions and the reported precipitation type occurrences tend to be higher in Atlantic Canada, although high values also occur in other regions. Trends of most temperature-based and precipitation-based indicators show little or no change despite a systematic warming in annual surface temperatures over Canada. Over the annual cycle, near-0 ∘C temperatures and precipitation often exhibit a pattern: short durations occur around summer, driven by the diurnal cycle, and a tendency toward longer durations around winter, associated with storms. There is also a tendency for near-0 ∘C surface temperatures to occur more often than expected relative to other temperature windows at some stations due, at least in part, to diabatic cooling and heating that take place with melting and freezing, respectively, in the atmosphere and at the surface.
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Antoni, Grégory. "On a New Kinetic Modelling Approach of the Irreversible Quasi-Surface Metallurgical Phase Transformations." Journal of Solid State Physics 2014 (July 20, 2014): 1–7. http://dx.doi.org/10.1155/2014/163725.
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Irreversible quasi-surface metallurgical phase transformations are the specific response of some metallic materials—such as metals and alloys—subjected to high thermomechanical loads applied very near their surface during the manufacturing processes or after being put into operation. These solid/solid phase transformations can be observed, for example, on the tread of many rails in railroad networks frequented by freight trains. The severe thermal and mechanical loads imposed on the surface of the rails and in the immediate vicinity of the surface by the wheel/rail contact often result in highly localized irreversible metallurgical transformations. A new kinetic model based on a previous study is presented here, which accounts more realistically for the nucleation and growth of these irreversible solid/solid phase transformations resulting from high thermomechanical loads. This metallurgical behavioral model was developed in the framework of continuum thermodynamics with gradients of temperature and internal variables.
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Zhou, Xinyi, Tie Li, Yijie Wei, and Ning Wang. "Scaling liquid penetration in evaporating sprays for different size diesel engines." International Journal of Engine Research 21, no. 9 (December 6, 2019): 1662–77. http://dx.doi.org/10.1177/1468087419889835.
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Scaled model experiments can greatly reduce the cost, time and energy consumption in diesel engine development, and the similarity of spray characteristics has a primary effect on the overall scaling results of engine performance and pollutant emissions. However, although so far the similarity of spray characteristics under the non-evaporating condition has been studied to some extent, researches on scaling the evaporating sprays are still absent. The maximum liquid penetration length has a close relationship with the spray evaporation processes and is a key parameter in the design of diesel engine spray combustion system. In this article, the similarity of maximum liquid penetration length is theoretically derived based on the hypotheses that the spray evaporation processes in modern high-pressure common rail diesel engines are fuel–air mixing controlled and local interphase transport controlled, respectively. After verifying that the fuel injection rates are perfectly scaled, the similarity of maximum liquid penetration length in evaporating sprays is studied for three scaling laws using two nozzles with hole diameter of 0.11 and 0.14 mm through the high-speed diffused back-illumination method. Under the test conditions of different fuel injection pressures, ambient temperatures and densities, the lift-off law and speed law lead to a slightly increased maximum liquid penetration length, while the pressure law can well scale the maximum liquid penetration length. The experimental results are consistent with the theoretical analyses based on the hypothesis that the spray evaporation processes are fuel–air mixing controlled, indicating that the local interphase transports of energy, momentum and mass on droplet surface are not rate-controlled steps with respect to spray evaporation processes.
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Muravev, Vitaliy V., Kirill A. Tapkov, Ludmila V. Volkova, and Andrei V. Platunov. "Strain Stress Model of the Rail with Crack in its Head and Estimation of its Operational Lifetime." Materials Science Forum 970 (September 2019): 177–86. http://dx.doi.org/10.4028/www.scientific.net/msf.970.177.
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The most common reason of the fatigue crack appearance is the presence of stresses in the rail. The process of stress strain state simulation for the R65 rail is presented in the paper. Values of residual stresses were modeled and chosen to be maximum allowed by GOST (State Standard): -77 MPa in the rail head, -125 MPa in the web and 106 MPa in rail foot. These stresses match the value-77 MPa measured by the acoustoelastic method from the center of the rolling surface of the rail. The influence of the crack at the highest level of the stress strain state was studied in cases of the maximum train load and its absence. According to results of modeling, stresses in the sharp edge of the crack can exceed the lowest acceptable by GOST (State Standard) value of the yield strength by more than 5 times in case of the presence of the train load. In case of the absence of the train load, the crack does not have a significant influence on the stress strain state. The modelling process was also used to study the influence of the installation temperature difference on the operational lifetime of the rail. The paper presents the description of the influence between the installation temperature difference and the crack initiation. According to modeling results and the rail defect catalogue, rails with the lowest acceptable mechanical characteristics are prohibited to be used after 300∙109 kg and higher tonnage.
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LeBleu, Charlene, Mark Dougherty, Keith Rahn, Amy Wright, Ryan Bowen, Rui Wang, Jeisson Orjuela, and Kaylee Britton. "Quantifying Thermal Characteristics of Stormwater through Low Impact Development Systems." Hydrology 6, no. 1 (February 5, 2019): 16. http://dx.doi.org/10.3390/hydrology6010016.
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Urbanization causes alteration of the thermal regime (surface, air, and water) of the environment. Heated stormwater runoff flows into lakes, streams, bays, and estuaries, which potentially increases the base temperature of the surface water. The amount of heat transferred, and the degree of thermal pollution is of great importance to the ecological integrity of receiving waters. This research reports on a controlled laboratory scale test to assess low impact development (LID) stormwater control measure impacts on the thermal characteristics of stormwater runoff. We hypothesize that LID stormwater control measures (SCMs) such as pervious surfaces and rain gardens/bioretention can be used to mitigate the ground level thermal loads from stormwater runoff. Laboratory methods in this study captured and infiltrated simulated stormwater runoff from four infrared heated substrate microcosms (pervious concrete, impervious concrete, permeable concrete pavers, and turf grass), and routed the stormwater through rain garden microcosms. A data logging system with thermistors located on, within, and at exits of the microcosms, recorded resulting stormwater temperature flux. Researchers compared steady state temperatures of the laboratory to previously collected field data and achieved between 30% to 60% higher steady state surface temperatures with indoor than outdoor test sites. This research helps establish baseline data to study heat removal effectiveness of pervious materials when used alone or in combination as a treatment train with other stormwater control measures such as rain gardens/bioretention.
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Leach, J. A., and R. D. Moore. "Winter stream temperature in the rain-on-snow zone of the Pacific northwest: influences of hillslope runoff and transient snow cover." Hydrology and Earth System Sciences Discussions 10, no. 10 (October 31, 2013): 12951–3003. http://dx.doi.org/10.5194/hessd-10-12951-2013.
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Abstract. Stream temperature dynamics during winter are less well studied than summer thermal regimes, but the winter season thermal regime can be critical for fish growth and development in coastal catchments. The winter thermal regimes of Pacific Northwest headwater streams, which provide vital winter habitat for salmonids and their food sources, may be particularly sensitive to changes in climate because they can remain ice-free throughout the year and are often located in rain-on-snow zones. This study examined winter stream temperature patterns and controls in small headwater catchments within the rain-on-snow zone at the Malcolm Knapp Research Forest, near Vancouver, British Columbia, Canada. Two hypotheses were addressed by this study: (1) winter stream temperatures are primarily controlled by advective fluxes associated with runoff processes and (2) stream temperatures should be depressed during rain-on-snow events, compared to rain-on-bare-ground, due to the cooling effect of rain passing through the snowpack prior to infiltrating the soil or being delivered to the stream as saturation-excess overland flow. A reach-scale energy budget analysis of two winter seasons revealed that the advective energy input associated with hillslope runoff overwhelms the effects of energy exchanges at the stream surface during rain and rain-on-snow events. Historical stream temperature data and modelled snowpack dynamics were used to explore the influence of transient snow cover on stream temperature over 13 winters. When snow was not present, daily stream temperature during winter rain events tended to increase with increasing air temperature. However, when snow was present, stream temperature was capped at about 5 °C, regardless of air temperature. The stream energy budget modelling and historical analysis support both of our hypotheses. A key implication is that climatic warming may generate higher winter stream temperatures in the rain-on-snow zone due to both increased rain temperature and reduced cooling effect of snow cover.
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Zhang, P., and T. Shu. "Influence of the orbital configuration of a four-rail electromagnetic launcher on Joule heat." Advanced Electromagnetics 11, no. 4 (October 5, 2022): 1–9. http://dx.doi.org/10.7716/aem.v11i4.2003.
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During the working process of electromagnetic launcher, the rapid temperature rise caused by heat accumulation has an important influence on the performance and life of the armature and rail. In order to better solve the thermal ablation problem of the armature and rail of the four-rail electromagnetic launcher, three different configurations of the rail and armature model are established, using the finite element method, the Joule heating characteristics of the three structures are simulated, analyzed and compared. The simulation results show that the Joule heat of the armatures of the three structures is concentrated at the throat, and the Joule heat of the rail is concentrated at the edge of the rail and the contact surface of the pivot rail; among the three structures, the electromagnetic launcher of the convex rail-concave armature structure has the smallest temperature rise rate, in addition, the peak temperature on the contact surface between the armature and the guide rail is the lowest, the safety of the ammunition is the highest, and the performance is more advantageous than the electromagnetic launcher of the other two structures.
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Sims, Elizabeth M., and Guosheng Liu. "A Parameterization of the Probability of Snow–Rain Transition." Journal of Hydrometeorology 16, no. 4 (July 29, 2015): 1466–77. http://dx.doi.org/10.1175/jhm-d-14-0211.1.
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Abstract When estimating precipitation using remotely sensed observations, it is important to correctly classify the phase of precipitation. A misclassification can result in order-of-magnitude errors in the estimated precipitation rate. Using global ground-based observations over multiple years, the influence of different geophysical parameters on precipitation phase is investigated, with the goal of obtaining an improved method for determining precipitation phase. The parameters studied are near-surface air temperature, atmospheric moisture, low-level vertical temperature lapse rate, surface skin temperature, surface pressure, and land cover type. To combine the effects of temperature and moisture, wet-bulb temperature, instead of air temperature, is used as a key parameter for separating solid and liquid precipitation. Results show that in addition to wet-bulb temperature, vertical temperature lapse rate affects the precipitation phase. For example, at a near-surface wet-bulb temperature of 0°C, a lapse rate of 6°C km−1 results in an 86% conditional probability of solid precipitation, while a lapse rate of −2°C km−1 results in a 45% probability. For near-surface wet-bulb temperatures less than 0°C, skin temperature affects precipitation phase, although the effect appears to be minor. Results also show that surface pressure appears to influence precipitation phase in some cases; however, this dependence is not clear on a global scale. Land cover type does not appear to affect precipitation phase. Based on these findings, a parameterization scheme has been developed that accepts available meteorological data as input and returns the conditional probability of solid precipitation.
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Gould, Marc, and Martin Jeffries. "Temperature variations in lake ice in central Alaska, USA." Annals of Glaciology 40 (2005): 89–94. http://dx.doi.org/10.3189/172756405781813825.
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AbstractIn winter 2002/03 and 2003/04, thermistors were installed in the ice on two shallow ponds in central Alaska, USA, in order to obtain data on ice temperatures and their response to increasing and decreasing air temperatures, and flooding and snow-ice formation. Snow depth and density, and ice thickness were also measured in order to understand how they affected and were affected by ice temperature variability. The lowest ice temperature (–15.5˚C) and steepest temperature gradient (–39.8˚Cm–1) occurred during a 9week period in autumn 2002/03 when there was no snow on the ice. With snow on the ice, temperature gradients were more typically in the range –20 to –5˚Cm–1. Average ice temperatures were lower during the warmer, first winter, and higher during the cooler, second winter because of differences in the depth and duration of the snow cover. Isothermal ice near the freezing point resulted from flooding and snow-ice formation, and brief episodes of warm weather with freezing rain. Under these circumstances, congelation-ice growth at the bottom of the ice cover was interrupted, even reversed. It is suggested that the patterns in temperatures brought about by the snow-ice formation and rain events may become more prevalent due to the increase in frequency of these events in central Alaska if temperature and precipitation change as predicted by Arctic climate models.
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Guo, Jun, Wei Li, Ze Feng Wen, and Xue Song Jin. "Mutual Interaction of Two Rail Surface Cracks under Thermo-Mechanical Contact Loading." Advanced Materials Research 97-101 (March 2010): 543–46. http://dx.doi.org/10.4028/www.scientific.net/amr.97-101.543.
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A finite element analysis is conducted to study the mutual interaction of two oblique surface cracks in rail under the wheel-rail full slip contact loading and frictional heating. In the present thermo-mechanical coupling finite element model, the heat-convection between the rail and ambient, heat transfer between the crack surfaces, and temperature-dependent material properties are taken into consideration. The variation of stress intensity factors with the distance between two cracks is investigated. The results reveal that the stress intensity factor K1 increases with an increase of the distance between the cracks. The effect of the distance between the cracks on the stress intensity factor range K2 is not significant.
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Zhao, Yanjun, Jun Xia, Zongxue Xu, Lei Zou, Yunfeng Qiao, and Peng Li. "Impact of Urban Expansion on Rain Island Effect in Jinan City, North China." Remote Sensing 13, no. 15 (July 29, 2021): 2989. http://dx.doi.org/10.3390/rs13152989.
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Rapid urbanization leads to changes in urban micro meteorology, such as the urban heat island effect and rain island effect, which eventually brings about urban waterlogging and other problems. In this study, the data of precipitation, temperatures and impervious surfaces with long series and high resolution are used to study the rain island effect in Jinan City, China. MK-Sen’s slope estimator, Pettitt test and Pearson correlation analysis are used to quantitatively analyze the impact of urban expansion on extreme climate indices. The results show that Jinan City has experienced rapid urbanization since the 1978 economic reform, and the impervious surface areas have increased from 311.68 km2 (3.04%) in 1978 to 2389.50 km2 (23.33%) in 2017. Urban expansion has a significant impact on temperature, with large variations in extreme temperature indices over the intensive construction area relative to the sparse construction area. The extreme temperature indices have a significant correlation with impervious surfaces. Jinan City shows a certain degree of rain island effect, which seems to be spatially correlated with the urban heat island effect. The frequency of short-duration precipitation events significantly increases and the intensity of precipitation events generally increases. The magnitude and frequency of extreme precipitation indices in the intensive construction area significantly increase when compared to that in the sparse construction area, and they have a significant correlation with impervious surfaces. There is a tendency that Jinan City’s rainfall center moves towards to the intensive construction area.
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Lynn, Barry H., Richard Healy, and Leonard M. Druyan. "An Analysis of the Potential for Extreme Temperature Change Based on Observations and Model Simulations." Journal of Climate 20, no. 8 (April 15, 2007): 1539–54. http://dx.doi.org/10.1175/jcli4219.1.
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Abstract The study analyzes observational climate data for June–August 1977–2004 and simulations of current and future climate scenarios from a nested GCM/regional climate model system to assess the potential for extreme temperature change over the eastern United States. Observational evidence indicates that anomalously warm summers in the eastern United States coincide with anomalously cool eastern Pacific sea surface temperatures, conditions that are conducive to geopotential ridging over the east, less frequent precipitation, and lower accumulated rainfall. The study also found that days following nighttime rain are warmer on average than daytime rain events, emphasizing the importance of the timing of precipitation on the radiation balance. Precipitation frequency and eastern Pacific sea surface temperature anomalies together account for 57% of the 28-yr variance in maximum surface temperature anomalies. Simulation results show the sensitivity of maximum surface air temperature to the moist convection parameterization that is employed, since different schemes produce different diurnal cycles and frequencies of precipitation. The study suggests that, in order to accurately project scenarios of extreme temperature change, models need to realistically simulate changes in the surface energy balance caused by the interannual variation of these precipitation characteristics. The mesoscale model that was realistic in this respect predicted much warmer mean and maximum surface air temperatures for five future summers than the parallel GCM driving simulation.
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Weingrill, Leonhard, Jörg Krutzler, and Norbert Enzinger. "Temperature Field Evolution during Flash Butt Welding of Railway Rails." Materials Science Forum 879 (November 2016): 2088–93. http://dx.doi.org/10.4028/www.scientific.net/msf.879.2088.
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Flash butt welding (FBW) of railway rails was investigated in this work. For this purpose samples of R260 rail steel and 60E1 profile were instrumented and subsequently welded on a Schlatter GAA 100 welding machine under industrial conditions. The intention is to gain in depth process knowledge by more accurately depicting thermal cycles for an entire welding sequence in the immediate proximity of the weld as well as in the heat affected zone (HAZ). A detailed characterization of the single stages of the heat up phase of the process is important. Additionally, the secondary welding voltage was measured simultaneously during the experiments to characterize the transient heat input. Moreover, these data were used in the analysis of the temperature signals to better cope with electrical interferences. Additionally, a finite element (FE) model of this FBW process was developed in the present work. Its implementation and solution is realized with the help of ESI’s FE-software SYSWELD. A strong coupled thermo-electrokinetical and metallurgical calculation routine was used. The model comprises the transition resistance at the welding surfaces as the main heat source to the process. Temperature dependent material properties and a corresponding metallurgical model based on an experimental CCT diagram of the rail steel R350HT are implemented in the simulation as well.
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Webster, P. J., G. Mills, X. D. Wang, W. P. Kang, and T. M. Holden. "Residual stresses in alumino-thermic welded rails." Journal of Strain Analysis for Engineering Design 32, no. 6 (August 1, 1997): 389–400. http://dx.doi.org/10.1243/0309324971513508.
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Neutron strain scanning has been used to map the residual stress field that is generated in a railway rail by a standard gap alumino-thermic weld made using routinely specified procedures. The longitudinal and vertical residual stress fields in the sections well away from the weld are characteristic of many unwelded rails, being generally tensile in the head and foot with balancing compression in the web. In the vicinity of the weld the residual stress patterns are very different. At the top and bottom surfaces of the rail the longitudinal residual stress field is strongly compressive, which is generally beneficial in that it would tend to inhibit the initiation and propagation of fatigue cracks from surface defects. Just at the surface the vertical residual stress attenuates to zero but internally, in the web region, both longitudinal and vertical components of the residual stress field are strongly tensile, which increases the susceptibility of that region to crack initiation and propagation from internal material defects. This pattern is consistent with practical operating experience, which is that most of the small proportion of alumino-thermic welds that do fail do so as a result of porosity or inclusions in the weld. It is found that the ‘boundaries’ of the ‘weld type’ residual stress fields do not coincide with the boundary of the weld, nor of the heat-affected zone, but correlate reasonably well with the positions of the extremities of the mould assembly and with the location of the steepest longitudinal temperature gradients.
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Liu, Pengzhan, Wenjun Zou, Jin Peng, and Furen Xiao. "Investigating the Effect of Grinding Time on High-Speed Grinding of Rails by a Passive Grinding Test Machine." Micromachines 13, no. 12 (November 30, 2022): 2118. http://dx.doi.org/10.3390/mi13122118.
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High-speed rail grinding is a unique passive grinding maintenance strategy that differs from conventional grinding techniques. Its grinding behavior is dependent on the relative motion between the grinding wheel and rail; hence, it possesses great speed and efficiency. In this study, the effects of the duration of grinding time and the increase in the number of grinding passes on the grinding of high-speed rails were investigated using passive grinding tests with a single grinding time of 10 s and 30 s and grinding passes of once, twice, and three times, respectively. The results show that when the total grinding time was the same, the rail removal, grinding ratio of grinding wheels, rail grinding effect, grinding force, and grinding temperature were better in three passes of 10 s grinding than in one pass of 30 s grinding, indicating that the short-time and multi-pass grinding scheme is not only conducive to improving the grinding efficiency and grinding quality in the high-speed rail grinding but can also extend the service life of the grinding wheels. Moreover, when the single grinding times were 10 s and 30 s, respectively, the grinding removal, grinding efficiency, grinding marks depth, and surface roughness of rail increased with the number of grinding passes, implying that the desired rail grinding objective can be achieved by extending the grinding time via the multi-pass grinding strategy. The results and theoretical analysis of this study will contribute to re-conceptualizing the practical operation of high-speed rail grinding and provide references for the development of the grinding process and grinding technology.