Track Profile Research Articles

Identification and control of a multiplace hyperbaric chamber.

This work presents the automation of a multiplace hyperbaric chamber. It includes the system modeling, identification, controller calculation and system validation. With the proposed approach a good pressure profile tracking and repeatability are achieved. Moreover, the proposed automation includes the implementation of powerful treatment tools such as Pause and Alleviation procedures. The control system implemented is based on a special zero-pole cancellation regulator. Experimental results are provided to illustrate the behavior of the automated chamber. It is important to remark that the chamber automated in this work is being successfully used in a real hospital since 2015 treating more than 40 patients per day, five days a week.

Effect of deposition material and heat treatment on wear and rolling contact fatigue of laser cladded rails

To develop a laser cladding technique for repairing rail surface damages due to rolling contact, wear and rolling contact fatigue characteristics of a set of laser cladded rails were investigated using a roller-on-disc test machine. Three deposition materials 410L, SS420 and Stellite 6, were chosen to clad a premium hypereutectoid steel rail under two different heat treatment processes. In the first heat treatment, only preheating at 350 °C was conducted and in the second heat treatment, preheating at 350 °C, post-heating at 350 °C (1 h) then slow-cooling to room temperature was conducted. Preheating the substrate was insufficient to prevent martensite formation resulting from the rapid cooling rate, whereas post heat treatment was beneficial for refining the lamellar spacing and eliminating martensite formation in the clad layer and heat affected zone. Following the roller-on-disc tests, wear loss was calculated from wear track profiles using a laser optical profilometer. The level of surface degradation, surface cracking and spalling was investigated using an optical microscope. Experimental results revealed that SS420 cladding had the highest wear resistant behaviour but severe surface cracks and spalling were found in the worn area. Stellite 6 cladding showed similar wear resistance as the parent substrate rail and the best fatigue resistance behaviour among the three cladded rail samples. Based on this research, Stellite 6 is the most promising deposition material for repairing rails by laser cladding.

Multi-color Localization Microscopy of Single Membrane Proteins in Organelles of Live Mammalian Cells

Knowledge about the localization of proteins in cellular subcompartments is crucial to understand their specific function. Here, we present a super-resolution technique that allows for the determination of the microcompartments that are accessible for proteins by generating localization and tracking maps of these proteins. Moreover, by multi-color localization microscopy, the localization and tracking profiles of proteins in different subcompartments are obtained simultaneously. The technique is specific for live cells and is based on the repetitive imaging of single mobile membrane proteins. Proteins of interest are genetically fused with specific, so-called self-labeling tags. These tags are enzymes that react with a substrate in a covalent manner. Conjugated to these substrates are fluorescent dyes. Reaction of the enzyme-tagged proteins with the fluorescence labeled substrates results in labeled proteins. Here, Tetramethylrhodamine (TMR) and Silicon Rhodamine (SiR) are used as fluorescent dyes attached to the substrates of the enzymes. By using substrate concentrations in the pM to nM range, sub-stoichiometric labeling is achieved that results in distinct signals. These signals are localized with ~15-27 nm precision. The technique allows for multi-color imaging of single molecules, whereby the number of colors is limited by the available membrane-permeable dyes and the repertoire of self-labeling enzymes. We show the feasibility of the technique by determining the localization of the quality control enzyme (Pten)-induced kinase 1 (PINK1) in different mitochondrial compartments during its processing in relation to other membrane proteins. The test for true physical interactions between differently labeled single proteins by single molecule FRET or co-tracking is restricted, though, because the low labeling degrees decrease the probability for having two adjacent proteins labeled at the same time. While the technique is strong for imaging proteins in membrane compartments, in most cases it is not appropriate to determine the localization of highly mobile soluble proteins.

MATHEMATICAL MODELING OF SECTIONS OF VARIABLE RIGIDITY IN FRONT OF ARTIFICIAL STRUCTURES

For the English abstract and full text of the article please see the attached PDF-File (English version follows Russian version).ABSTRACT The article deals with the features of the transition zone from the ballast under-sleeper base to the bridge structure with various types of span structures, as well as the sections of the ballastless track, conjugated with the transient zone. An analytical model is proposed for describing the dynamic behavior of a railway track in the form of a transversely isotropic plate with variable rigidity parameters. Examples of the use of the proposed model for calculating the dynamic depression of a roadbed under the influence of a rolling stock with different freight and speed characteristics are given. Keywords: railway, bridge, roadbed, residual deformation, variable rigidity section, track depression, slope, elastic wave, track profile, transversal-isotropic plate.

Investigation of flux dependent sensitivity on single event effect in memory devices**Project supported by the National Natural Science Foundation of China (Grant Nos. U1532261, 11690041, and 11675233).

Heavy-ion flux is an important experimental parameter in the ground based single event tests. The flux impact on a single event effect in different memory devices is analyzed by using GEANT4 and TCAD simulation methods. The transient radial track profile depends not only on the linear energy transfer (LET) of the incident ion, but also on the mass and energy of the ion. For the ions with the energies at the Bragg peaks, the radial charge distribution is wider when the ion LET is larger. The results extracted from the GEANT4 and TCAD simulations, together with detailed analysis of the device structure, are presented to demonstrate phenomena observed in the flux related experiment. The analysis shows that the flux effect conclusions drawn from the experiment are intrinsically connected and all indicate the mechanism that the flux effect stems from multiple ion-induced pulses functioning together and relies exquisitely on the specific response of the device.

Dynamic evolutions of swift heavy ion induced latent tracks under electron bombardment from TEM

Abstract Dynamic evolutions of morphology and size of swift heavy ion (SHI) induced latent tracks in muscovite mica were explored using in situ transmission electron microscopy (TEM) in this paper. Prior to the measurements, muscovite mica sheets were irradiated with Kr and Bi ions with electronic energy loss (dE/dx)e of 5.9 keV/nm and 31.5 keV/nm, respectively. It is observed in TEM micrographs that the latent tracks in mica are continuously along the cross section view of the ion tracks. The track profile is not found dramatically uniform but rather it is found slightly fluctuating for similar (dE/dx)e values. In situ TEM observation clarify that atoms in the track halo are unstable compared with the lattice atoms in the vicinity of the track. Point defects induced by the electron bombardment are generated preferentially around the track core, which results in the increased diameter of the track.

Alternative Approach to Extract the Bulk Etching Rate of PADC Nuclear Detector

The paper aims to propose the maximum track length (L max ) measurement as an alternative approach to evaluate and extract the bulk etch rate (V b ) of the nuclear detector PADC CR-39, and compare it with the results obtained by the removal layer thickness measurement of the etched detector. The alternative L max -method mainly relies on the measuring the length of the etched tracks, their maximum values and saturation times from the obtained track profile images. The detectors were irradiated with different energies of alpha particles emitted from the 241 Am source and then etched in a 6.5 N NaOH solution at 70�1 o C for different successive time intervals. In order to calculate V b , the maximum length of the tracks and their saturation times were determined corresponding to the energies of the alpha particles used. A direct proportion between the maximum length of the tracks and the energy of the alpha particle was observed. However, the value of V b is found to be 1.344�0.0202 mm h -1 obtained using the L max -method, and it was consistent with that computed by the method based on the measurement of the thickness difference of the etched detector which was 1.354�0.065 mm h -1 .

Effects of Microstructure of Compacted Graphite Iron in Tribological Strategy

In this paper, the effect of compacted graphite iron (CGI) microstructure has been investigated in tribological strategy. From industrial context, two coatings have been chosen: a single layer coating (physical vapor deposition (PVD)) and a multilayer coating (chemical vapor deposition (CVD)). Pin-on-disk tests have been done to analyze wear mechanisms and to directly obtain the coefficient of friction. Rotation speed of the disk has been adjusted to get the same linear velocity on different disk radii to get up to 150 m min−1 similar to machining condition. Three-dimensional (3D) profilometer, scanning electron microscopy, and nano-indentation were used to observe the track profiles, the pin, and the disk wears and to measure the hardness of microstructure components, respectively. Results showed that PVD coating was more abrasive and had more volume of sticking materials. Chemical vapor deposition coating, which could be the most appropriate for machining CGI, has a real antisticking property and has less friction coefficient than PVD coating. But the presence of small TiCN precipitates in CGI material has a proven negative effect in CVD coating lifetime.

MODELLING AND ANALYSIS OF AN IRREGULAR RAILWAY TRACK SYSTEM FOR COMPUTATION OF CRITICAL VELOCITY FOR LIMITING VERTICAL ACCELERATION

The irregularity in the railway tracks is a very common topic of interest among the researchers in recent times. The trains run on the tracks with very high velocities to meet the demands of the passengers. But due to the unevenness of the track, the body of the train car faces vertical accelerations, which in turn causes discomfort to the passengers sitting inside the train car. In the present report, vertical acceleration is analyzed for uneven tracks by taking the car body as a single degree of freedom model. The investigation shows a clear explanation of the critical velocity values for the train, so as to maintain the passenger comfort conditions. Random sinusoidal curves were generated using MATLAB to analyze the random unevenness of the track. It is observed that the vertical accelerations in the car body are directly proportional to the speed of the train. Finally, a critical velocity is proposed for a train running on uneven sinusoidal profile track such that, the vertical acceleration not exceeding 0.2g.

The benefits of mechatronically-guided railway vehicles: A multi-body physics simulation study

Mechatronically-guided railway vehicles are of paramount importance in addressing the increasing interest in reducing wheel-rail wear and improving guidance and steering. Conventional passively-guided rail vehicles are limited by the mechanical constraints of the suspension elements. Currently, a typical rail vehicle suspension needs to be sufficiently stiff to stabilize the wheelsets while being complaint enough to negotiate curved track profiles. The suspension is therefore a compromise for the contradictory requirements of curving and stability.In mechatronic vehicles, actuators are used with the conventional suspension components to provide additional stiffness or damping forces needed to optimise a vehicle for a wide variety of scenarios, and not rely on a sub optimal combination of passive components.This research demonstrates the benefits of active guidance and steering when compared to a conventional vehicle using simulation results from a multi-body simulation software Simpack. It also provides insights into the relative performance of the mechatronic schemes. The Simpack modeling allows for a complex model with high fidelity, which provides an additional level of proof of the control algorithms working on a real rail vehicle. Each vehicle is assessed in terms of guidance on straight track, steering on curved track, actuation requirements and wheel-rail wear. Significant benefits are demonstrated in one of the guided vehicles with independently-rotating wheelsets.

Improvement of railway ballast maintenance approach, incorporating ballast geometry and fouling conditions

Ballast plays an important role in the stability of railway track systems. The effectiveness of the ballast in maintaining the track stability is very much dependent on its mechanical conditions. The available ballast maintenance approaches are mainly based on only track geometry conditions (such as track profile) which do not sufficiently reflect the ballast mechanical behaviors. That is, the ballast potential of degradation (i.e., ballast long term behaviors) has been omitted. This makes the effectiveness of the current ballast maintenance approach questionable, indicating a need for a more comprehensive and effective ballast conditions assessment technique. In response to this need, two ballast condition indices based on ballast geometry degradation (BGI) and the level of ballast fouling (BFI) as the main indicators of ballast mechanical behavior were developed. The BGI is a function of the standard deviations of track alignment, unevenness and twist. The BFI was developed based on the data obtained from the ground penetration radar (GPR). Making use of the new indices, a more reliable maintenance algorithm was developed. Through illustrations of the applicability of the new maintenance algorithm in a railway line, it was shown that the new algorithm causes a considerable improvement in the maintenance effectiveness and an increase in the life cycle of railway tracks by making more effective allocation of resources and more accurate maintenance planning.

Effect of the sorting track profile change on the it’s occupancy quality at train humping

To increase the hump yard capacity, it is necessary to ensure high quality of sorting track occupancy. The purpose of this paper is to study the effect of changing the track profile on the quality of its occupancy. The simulation model developed for occupancy of sorting tracks based on the calculation of the speed of the cut and taking the following into consideration was used for the study: the possibility of starting the cut movement after a stop, errors in operation of the devices in charge of the speed of releasing the cut to the track, the possibility of displacement of the cars when the next cut collides with them. A real profile of the sorting facility track was analyzed as an example of it. It was determined that the profile caused strong effect on the track occupancy quality. The sagging of the profile causes an increase in the probability of collision of the cuts with exceeding the permissible speed. An increase in the up-gradient reduces the range of the run-off distance, which in turn causes an increase in the number of car back-ins. Profile correction will allow increasing the track occupancy quality.

Исследование влияния изменения профиля пути сортировочного парка на качество его заполнения при расформировании составов

Исследование влияния изменения профиля пути сортировочного парка на качество его заполнения при расформировании составов

Simulation of processes of electric power consumption for traction in conditions of changing the traffic schedule of freight trains at the electrified sections

The paper is devoted to the solution of the problem of increasing the energy efficiency of the transportation process on the electrified sections of the railways. The task is considered in the aspect of energy efficiency when comparing forecasted traffic schedules with each other and assessing the effectiveness of implementing the forecasted and executed schedule of train traffic at the section. The basis for the calculations is a simulation modeling of the interaction between the electric rolling stock and the traction power supply system at the sections with different track profiles. Simulation modeling was carried out for the conditions of changing the traffic schedule of freight trains and maintaining the amount of traffic and the amount of work unchanged. The results of the change in the amount of electric power for traction and the level of unbalance of energy for existing sections of constant and alternating current are used as the basis for construction of approximating models, in the function of which regression and neural network models are used. Comparison of the results of approximation of the considered models for the estimation of changes in amount of electric power for traction and unbalance is made. Models with the best results of approximation to simulation results are determined.

Optimization of noise abatement aircraft terminal routes using a multi-objective evolutionary algorithm based on decomposition

Recently, a multi-objective evolutionary algorithm based on decomposition (MOEA/D) has emerged as a potential method for solving multi-objective optimization problems (MOPs) and attracted much attention from researchers. In MOEA/D, the MOPs are decomposed into a number of scalar optimization sub-problems, and these sub-problems are optimized concurrently by only utilizing the information from their neighboring sub-problems. Thanks to these advantages, MOEA/D has demonstrated to be more efficient than the non-dominated sorting genetic algorithm II (NSGA-II) and other methods. However, its applications to practical problems are still limited, especially in the domain of aerospace engineering. Therefore, this paper aims to present a new application of MOEA/D for the optimal design of noise abatement aircraft terminal routes. First, in order to optimize aircraft noise for aircraft terminal routes while taking into account the interests of various stakeholders, bi-objective optimization problems including noise and fuel consumption are formulated, in which both the ground track and vertical profile of a terminal route are optimized simultaneously. Then, MOEA/D is applied to solve these problems. Furthermore, to ensure the design space of vertical profiles is always feasible during the optimization process, a trajectory parameterization technique recently proposed is also used. This technique aims at reducing the number of model evaluations of MOEA/D and hence the computational cost will decrease significantly. The efficiency and reliability of the developed method are evaluated through case studies for departure and arrival routes at Rotterdam The Hague Airport in the Netherlands.

Methodology for the navigation optimization of a terrain-adaptive unmanned ground vehicle

The goal of this article is to design a navigation algorithm to improve the capabilities of an all-terrain unmanned ground vehicle by optimizing its configuration (the angles between its legs and its body) for a given track profile function. The track profile function can be defined either by numerical equations or by points. The angles between the body and the legs can be varied in order to improve the adaptation to the ground profiles. A new dynamic model of an all-terrain vehicle for unstructured environments has been presented. The model is based on a half-vehicle and a quasi-static approach and relates the dynamic variables of interest for navigation with the topology of the mechanism. The algorithm has been created using a simple equation system. This is an advantage over other algorithms with more complex equations which need more time to be calculated. Additionally, it is possible to optimize to any ground-track-profile of any terrain. In order to prove the soundness of the algorithm developed, some results of different applications have been presented.

Ocena stanu torowiska z wykorzystaniem metody Grey Relational Analysis

The article concerns the developed methodology for assessing the technical condition of a tramway track. Thanks to the data collected from multiple tram journeys equipped with an on-board vibration recording system, it was possible to create profiles of crossings through track sections in different technical condition. In order to identify the track condition, an algorithm based on the gray-scale modeling was proposed, and a similarity comparison between the obtained track profiles. A new measure of similarity has been proposed that has not been used so far in gray-scale modeling. The obtained results confirm the applicability of the proposed methodology

High downforce race car vertical dynamics: aerodynamic index

ABSTRACTRace car performance is strongly affected by aerodynamics. Due to downforce generated by the vehicle floor (i.e. diffuser), vehicle ride heights are key parameters to improve performance, and the coupling of aerodynamics and suspension is one of the key points of race car setting. This work focuses on the suspension and aerodynamic coupling from the vertical dynamics point of view. Besides road holding performance, for race cars, aerodynamic performance and stability are major factors. Downforce decreases laptime (the main performance target) but pitch instability is a non-desired effect that can happen in high downforce race cars. A new vertical dynamic performance index is proposed through the use of simulation to improve aerodynamic performance and understand the pitch instability phenomenon. This new index uses all relevant vehicle nonlinearities related to vertical dynamics and can handle a specific track profile and vehicle speed range, allowing the analysis be conducted according to a circuit specification. A previously validated Formula 3 car model was used as an example.

Communication-Based Train Control System Performance Optimization Using Deep Reinforcement Learning

Communication-based train control (CBTC) systems are automated train control systems based on continuous and bidirectional train-ground communications. CBTC is the direction of future train control systems. Complex channel condition and frequent handoff can severely affect urban rail CBTC train-ground communication performance, and consequently affect CBTC operation efficiency. Current research regarding CBTC does not consider the impact of train-ground communications on train control performance. This paper studies the joint optimization of communication and control in CBTC systems. With the objective to minimize the optimal operation profile tracking error and energy consumption, linear quadratic cost is defined as the control performance measure. In order to ensure train operation safety, the optimization model puts constraints on train control actions related to safety. Moreover, based on the stochastic channel characteristics and the real-time train position information, handoff decision and train control policy are jointly optimized using deep reinforcement learning. Extensive simulation results based on real-field channel measurements illustrate that the proposed optimization method can significantly improve the train control performance in CBTC systems, and CBTC systems need to sacrifice part of performance to ensure system safety.

An Efficient Application of the MOEA/D Algorithm for Designing Noise Abatement Departure Trajectories

In an effort to allow to increase the number of aircraft and airport operations while mitigating their negative impacts (e.g., noise and pollutant emission) on near-airport communities, the optimal design of new departure routes with less noise and fuel consumption becomes more important. In this paper, a multi-objective evolutionary algorithm based on decomposition (MOEA/D), which recently emerged as a potential method for solving multi-objective optimization problems (MOPs), is developed for this kind of problem. First, to minimize aircraft noise for departure routes while taking into account the interests of various stakeholders, bi-objective optimization problems involving noise and fuel consumption are formulated where both the ground track and vertical profile of a departure route are optimized simultaneously. Second, in order to make the design space of vertical profiles feasible during the optimization process, a trajectory parameterization technique recently proposed is employed. Furthermore, some modifications to MOEA/D that are aimed at significantly reducing the computational cost are also introduced. Two different examples of departure routes at Schiphol Airport in the Netherlands are shown to demonstrate the applicability and reliability of the proposed method. The simulation results reveal that the proposed method is an effective and efficient approach for solving this kind of problem.