Asymmetry of rail circuits with dsh-2 relay

2017 ◽  
pp. 280-297
Author(s):  
Alexander Manakov ◽  
Andrey Kabetskiy ◽  
Alexander Troshin ◽  
Yuriy Pashaev
Keyword(s):  
Spin Asymmetry ◽  
Practical Importance ◽  
Rolling Stock ◽  
Voltage Sags ◽  
Natural Experiments ◽  
Longitudinal Asymmetry ◽  
Rail Line ◽  
Track Circuits ◽  
The Impact ◽  
Line Resistance

Objective: To consider the causes and ways to reduce voltage sags on resonant track relays of track circuits with dssh-2 relays. Methods: Analysis of voltage depressions causes on a track relay with track circuit, free of rolling stock on rails, was carried out by means of natural experiments with oscillography and voltage on a track relay analysis, as well as measurement of insulation resistance of rail lines and the inductances of the main windings of transformers. Results: It was determined that one of the causes of voltage depressions on road relays were the transverse asymmetry of the resistance of rail lines caused by metal chips generated by pantograph trains when passing a nonoverlayable interval on the approach to the station. The impact of longitudinal spin asymmetry of rail line resistance on voltage sags, which is formed by a variation in inductance of the primary winding sections of an impedance bond. The relationship of voltage sags and the methods of rolling stock handling as well as places of electric power cut-offs’ was studied. Practical importance: The rule of connecting the main windings of transformers to the rails of sections was proposed, in order to reduce the impact of the variation in total inductance of transformers’ sections on the longitudinal asymmetry of rail line resistance. The conducted research made it possible to determine the causes and ways to reduce voltage dips on the resonant track relays of track circuits with dssh-2 relays.

COMPARATIVE ANALYSIS OF THE RESULTS OF FORCE IMPACT ON THE TRACK WITH APPLICATION OF SCHLUMPF, “RZhD-2016” AND “NVTs-TKP” METHODS

2017 ◽  
pp. 174-189
Author(s):  
Anton Petrov ◽  
Kirill Yeliseyev ◽  
Alexander Tretyakov ◽  
Alexander Marykyn ◽  
Victor Nikityn ◽  
...  
Keyword(s):  
Strain Gauge ◽  
Dynamic Testing ◽  
Practical Importance ◽  
Direct Methods ◽  
Rolling Stock ◽  
Dynamic Tests ◽  
Data Logging ◽  
Continuous Record ◽  
Force Impact ◽  
The Impact

Objective: To improve the integrity of running and dynamic testing results of force impact on the track, on the basis of modern facilities of data logging and wireless transmission from rotary elements of a car, as well as the change from indirect to direct methods of measurement. Methods: Comparative running and dynamic tests of the impact on the track were held simultaneously on the same section of the track, using three methods of logging vertical and side forces, that is Schlumpf (State Standard R 55050-2012), “RZhD-2016” and “NVTs-TKP” methods. The key difference of the third method was the application of strain-gauge set of wheels (TKP), making it possible to keep a continuous record of forces acting in the “wheel-rail” system throughout the track, whereas other methods allowed for the realization of the above mentioned only on districts with a limited amount of sections. Results: According to the results of comparative testing, a conclusion was made on the improvement of integrity and justification of the method of “NVTs-TKP” with an application of strain-gauge set of wheels. Practical importance: It was suggested to apply “NVTs-TKP” method to implementing organizations of running and dynamic tests when evaluating the load of an innovative rolling stock on the track.

scholarly journals Elastic characteristics of the underrail base of a ballastless railway track

2021 ◽  
Vol 2021 (4) ◽  
pp. 469-479
Author(s):  
Alexey F. KOLOS ◽  
◽  
Ksenia I. IVANOVA ◽  
Keyword(s):  
Practical Importance ◽  
Operating Conditions ◽  
Railway Track ◽  
Rolling Stock ◽  
Relative Stiffness ◽  
Ballastless Track ◽  
Full Scale Tests ◽  
The Impact ◽  
Track Modulus ◽  
Elastic Characteristics

Objective: Experimental determination track modulus and the coeffi cient of relative stiffness of underrail base and the rail, which are the main elastic characteristics that determine the stresses in the structural elements of track superstructure under the impact force from the train. The values of these parameters for a track with a ballast layer are well studied, in contrast to a ballastless track. Comparison of the elastic characteristics of a ballastless railway track with analogs of a track on ballast, as well as an assessment of their effect on the stress-strain state of the superstructure elements of a ballastless track. Methods: When carrying out full-scale tests, strain-gauge methods for measuring stresses in the elements of the track superstructure were used. The obtained values were processed by the methods of mathematical statistics. One statistical series included the values of stresses corresponding to one type of rolling stock, fi xed axle load and train speed, changing by no more than 10 km/h. The probability level in processing the results was taken in all cases equal to 0,994. Results: The values of track modulus and the coeffi cient of the relative stiffness of the underrail base and the rail were obtained for a ballastless structure of the RHEDA 2000 type. Practical importance: The results allow us to consider the rail as a beam lying on a solid elastic foundation in relation to the ballastless track and use the existing calculation methods for the design of ballastless track structures depending on the operating conditions.

On equilibrium slope of station gradient

2020 ◽  
Vol 17 (4) ◽  
pp. 575-582
Author(s):  
V. I. Smirnov ◽  
◽  
S. A. Vidiushenkov ◽  
Keyword(s):  
Differential Equation ◽  
Wind Speed ◽  
Analytical Solution ◽  
Piecewise Linear ◽  
Practical Importance ◽  
Wind Loading ◽  
Rolling Stock ◽  
Slope Gradient ◽  
Air Resistance ◽  
The Impact

Objective: Defi nition of slope gradient for station track profi le elevation at which self-induced runningoff of loose running stock. Methods: Simulation of rolling stock movement based on analytical solution of differential equation of equilibrium of cut of wagons. Cut of wagons on station track is treated as a solid on a gradient plane with a mass equal to the mass of the cut of wagons. Track profi le elevation is approximated by piecewise-linear right line. Results: The paper shows that hopper wagons have the highest probability of self-induced running-off due to high air resistance coeffi cient. For three-element profi le the hypothetic wind speed at which running-off of wagons is possible remains relatively low, about 14 metres per second, which leaves the problem of effective fastening of wagons at stations still current. Practical importance: The solution obtained permits evaluating the probability of running-off of loose rolling stock under the action of gravity and under the impact of wind loading, as well as refi ne the norms for fastening of wagons at a station. The proposed calculation scheme also permits gauging the strength with which moving wagons would impact the backing thrust in case it is installed at the end of a track section.

The development of service conditions for special-purpose cars based on the results of full-scale tests

2018 ◽  
pp. 455-462
Author(s):  
Dmitriy Arshintsev ◽  
Sergey Tolmachev ◽  
Alexander Brzhezovskiy
Keyword(s):  
Practical Importance ◽  
Full Scale ◽  
Rolling Stock ◽  
Normative Documents ◽  
Regulatory Documents ◽  
Loading Mode ◽  
Multiple Unit ◽  
Service Conditions ◽  
Full Scale Tests ◽  
The Impact

Objective: To develop the conditions of special cargo railway cars, multi-axis container cars and railway non-autonomous multiple unit trains circulation for transportation of special-purpose goods on public railways of OAO “RZhD”. The speeds of such trains can be higher in comparison with the speeds established by the existing normative documents of JSC “Russian Railways” for cargo trains. Special-purpose cars in nominal loading mode circulate in a train set with a unit locomotive. Methods: The assessment of conditions of the special-purpose rolling stock circulation was carried out by the results of tests on the line as well as the impact on the track and pointwork in the accredited centers, based on the regulations of GOST R 55050–2012. Results: The conditions for the fleet circulation consisting of 8–32-axle special-purpose railway cars, multiaxial container cars and non-autonomous multiple unit trains were established. Practical importance: A set of regulatory documents of JSC “Russian Railways” was developed in the form of regulations on technical conditions of special-purpose railway cars, conveyors and multiple unit trains designed for transportation of special purpose freight.

scholarly journals On Kaufmann's theory of the impact of the pianoforte hammer

1920 ◽  
Vol 97 (682) ◽  
pp. 99-110 ◽  
Keyword(s):  
Initial Conditions ◽  
Practical Importance ◽  
Prima Facie ◽  
Point Of View ◽  
Infinite Length ◽  
Modes Of Vibration ◽  
Rigorous Treatment ◽  
The Subject ◽  
Set Up ◽  
The Impact

The theory of the vibrations of the pianoforte string put forward by Kaufmann in a well-known paper has figured prominently in recent discussions on the acoustics of this instrument. It proceeds on lines radically different from those adopted by Helmholtz in his classical treatment of the subject. While recognising that the elasticity of the pianoforte hammer is not a negligible factor, Kaufmann set out to simplify the mathematical analysis by ignoring its effect altogether, and treating the hammer as a particle possessing only inertia without spring. The motion of the string following the impact of the hammer is found from the initial conditions and from the functional solutions of the equation of wave-propagation on the string. On this basis he gave a rigorous treatment of two cases: (1) a particle impinging on a stretched string of infinite length, and (2) a particle impinging on the centre of a finite string, neither of which cases is of much interest from an acoustical point of view. The case of practical importance treated by him is that in which a particle impinges on the string near one end. For this case, he gave only an approximate theory from which the duration of contact, the motion of the point struck, and the form of the vibration-curves for various points of the string could be found. There can be no doubt of the importance of Kaufmann’s work, and it naturally becomes necessary to extend and revise his theory in various directions. In several respects, the theory awaits fuller development, especially as regards the harmonic analysis of the modes of vibration set up by impact, and the detailed discussion of the influence of the elasticity of the hammer and of varying velocities of impact. Apart from these points, the question arises whether the approximate method used by Kaufmann is sufficiently accurate for practical purposes, and whether it may be regarded as applicable when, as in the pianoforte, the point struck is distant one-eighth or one-ninth of the length of the string from one end. Kaufmann’s treatment is practically based on the assumption that the part of the string between the end and the point struck remains straight as long as the hammer and string remain in contact. Primâ facie , it is clear that this assumption would introduce error when the part of the string under reference is an appreciable fraction of the whole. For the effect of the impact would obviously be to excite the vibrations of this portion of the string, which continue so long as the hammer is in contact, and would also influence the mode of vibration of the string as a whole when the hammer loses contact. A mathematical theory which is not subject to this error, and which is applicable for any position of the striking point, thus seems called for.

scholarly journals Understanding and responding to COVID-19 in Wales: protocol for a privacy-protecting data platform for enhanced epidemiology and evaluation of interventions

BMJ Open ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. e043010
Author(s):  
Jane Lyons ◽  
Ashley Akbari ◽  
Fatemeh Torabi ◽  
Gareth I Davies ◽  
Laura North ◽  
...  
Keyword(s):  
Policy Development ◽  
Healthcare Utilisation ◽  
Population Data ◽  
Population Level ◽  
Risk Groups ◽  
Service Utilisation ◽  
Natural Experiments ◽  
Spread Of Infection ◽  
The Impact

IntroductionThe emergence of the novel respiratory SARS-CoV-2 and subsequent COVID-19 pandemic have required rapid assimilation of population-level data to understand and control the spread of infection in the general and vulnerable populations. Rapid analyses are needed to inform policy development and target interventions to at-risk groups to prevent serious health outcomes. We aim to provide an accessible research platform to determine demographic, socioeconomic and clinical risk factors for infection, morbidity and mortality of COVID-19, to measure the impact of COVID-19 on healthcare utilisation and long-term health, and to enable the evaluation of natural experiments of policy interventions.Methods and analysisTwo privacy-protecting population-level cohorts have been created and derived from multisourced demographic and healthcare data. The C20 cohort consists of 3.2 million people in Wales on the 1 January 2020 with follow-up until 31 May 2020. The complete cohort dataset will be updated monthly with some individual datasets available daily. The C16 cohort consists of 3 million people in Wales on the 1 January 2016 with follow-up to 31 December 2019. C16 is designed as a counterfactual cohort to provide contextual comparative population data on disease, health service utilisation and mortality. Study outcomes will: (a) characterise the epidemiology of COVID-19, (b) assess socioeconomic and demographic influences on infection and outcomes, (c) measure the impact of COVID-19 on short -term and longer-term population outcomes and (d) undertake studies on the transmission and spatial spread of infection.Ethics and disseminationThe Secure Anonymised Information Linkage-independent Information Governance Review Panel has approved this study. The study findings will be presented to policy groups, public meetings, national and international conferences, and published in peer-reviewed journals.

scholarly journals Minimization of the Line Resistance Impact on Memdiode-Based Simulations of Multilayer Perceptron Arrays Applied to Pattern Recognition

2021 ◽  
Vol 11 (1) ◽  
pp. 9
Author(s):  
Fernando Leonel Aguirre ◽  
Nicolás M. Gomez ◽  
Sebastián Matías Pazos ◽  
Félix Palumbo ◽  
Jordi Suñé ◽  
...  
Keyword(s):  
Pattern Recognition ◽  
Ex Situ ◽  
Multilayer Perceptrons ◽  
Spice Simulation ◽  
Large Dataset ◽  
High Line ◽  
Calibration Algorithm ◽  
The Impact ◽  
Line Resistance

In this paper, we extend the application of the Quasi-Static Memdiode model to the realistic SPICE simulation of memristor-based single (SLPs) and multilayer perceptrons (MLPs) intended for large dataset pattern recognition. By considering ex-situ training and the classification of the hand-written characters of the MNIST database, we evaluate the degradation of the inference accuracy due to the interconnection resistances for MLPs involving up to three hidden neural layers. Two approaches to reduce the impact of the line resistance are considered and implemented in our simulations, they are the inclusion of an iterative calibration algorithm and the partitioning of the synaptic layers into smaller blocks. The obtained results indicate that MLPs are more sensitive to the line resistance effect than SLPs and that partitioning is the most effective way to minimize the impact of high line resistance values.

scholarly journals Droplet impact onto a spring-supported plate: analysis and simulations

2021 ◽  
Vol 128 (1) ◽  
Author(s):  
Michael J. Negus ◽  
Matthew R. Moore ◽  
James M. Oliver ◽  
Radu Cimpeanu
Keyword(s):  
High Speed ◽  
Flexible Substrate ◽  
Practical Importance ◽  
Hybrid Approach ◽  
Hydrodynamic Pressure ◽  
Analytical Framework ◽  
Canonical System ◽  
Linear Process ◽  
Plate Motion ◽  
The Impact

AbstractThe high-speed impact of a droplet onto a flexible substrate is a highly non-linear process of practical importance, which poses formidable modelling challenges in the context of fluid–structure interaction. We present two approaches aimed at investigating the canonical system of a droplet impacting onto a rigid plate supported by a spring and a dashpot: matched asymptotic expansions and direct numerical simulation (DNS). In the former, we derive a generalisation of inviscid Wagner theory to approximate the flow behaviour during the early stages of the impact. In the latter, we perform detailed DNS designed to validate the analytical framework, as well as provide insight into later times beyond the reach of the proposed analytical model. Drawing from both methods, we observe the strong influence that the mass of the plate, resistance of the dashpot, and stiffness of the spring have on the motion of the solid, which undergo forced damped oscillations. Furthermore, we examine how the plate motion affects the dynamics of the droplet, predominantly through altering its internal hydrodynamic pressure distribution. We build on the interplay between these techniques, demonstrating that a hybrid approach leads to improved model and computational development, as well as result interpretation, across multiple length and time scales.

scholarly journals A next step in disruption management: combining operations research and complexity science

2021 ◽  
Author(s):  
Mark M. Dekker ◽  
Rolf N. van Lieshout ◽  
Robin C. Ball ◽  
Paul C. Bouman ◽  
Stefan C. Dekker ◽  
...  
Keyword(s):  
Operations Research ◽  
Complexity Science ◽  
Rolling Stock ◽  
Accurate Information ◽  
Disruption Management ◽  
Railway Systems ◽  
Decentralized Decision Making ◽  
Control Situations ◽  
Management Techniques ◽  
The Impact

AbstractRailway systems occasionally get into a state of being out-of-control, meaning that barely any train is running, even though the required resources (infrastructure, rolling stock and crew) are available. Because of the large number of affected resources and the absence of detailed, timely and accurate information, currently existing disruption management techniques cannot be applied in out-of-control situations. Most of the contemporary approaches assume that there is only one single disruption with a known duration, that all information about the resources is available, and that all stakeholders in the operations act as expected. Another limitation is the lack of knowledge about why and how disruptions accumulate and whether this process can be predicted. To tackle these problems, we develop a multidisciplinary framework combining techniques from complexity science and operations research, aiming at reducing the impact of these situations and—if possible—avoiding them. The key elements of this framework are (i) the generation of early warning signals for out-of-control situations, (ii) isolating a specific region such that delay stops propagating, and (iii) the application of decentralized decision making, more suited for information-sparse out-of-control situations.

scholarly journals Conceptualising natural and quasi experiments in public health

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Frank de Vocht ◽  
Srinivasa Vittal Katikireddi ◽  
Cheryl McQuire ◽  
Kate Tilling ◽  
Matthew Hickman ◽  
...  
Keyword(s):  
Public Health ◽  
Study Design ◽  
Grey Literature ◽  
Public Health Research ◽  
Natural Experiments ◽  
Target Trial ◽  
Design Elements ◽  
Randomized Controlled ◽  
Study Designs ◽  
The Impact

Abstract Background Natural or quasi experiments are appealing for public health research because they enable the evaluation of events or interventions that are difficult or impossible to manipulate experimentally, such as many policy and health system reforms. However, there remains ambiguity in the literature about their definition and how they differ from randomized controlled experiments and from other observational designs. We conceptualise natural experiments in the context of public health evaluations and align the study design to the Target Trial Framework. Methods A literature search was conducted, and key methodological papers were used to develop this work. Peer-reviewed papers were supplemented by grey literature. Results Natural experiment studies (NES) combine features of experiments and non-experiments. They differ from planned experiments, such as randomized controlled trials, in that exposure allocation is not controlled by researchers. They differ from other observational designs in that they evaluate the impact of events or process that leads to differences in exposure. As a result they are, in theory, less susceptible to bias than other observational study designs. Importantly, causal inference relies heavily on the assumption that exposure allocation can be considered ‘as-if randomized’. The target trial framework provides a systematic basis for evaluating this assumption and the other design elements that underpin the causal claims that can be made from NES. Conclusions NES should be considered a type of study design rather than a set of tools for analyses of non-randomized interventions. Alignment of NES to the Target Trial framework will clarify the strength of evidence underpinning claims about the effectiveness of public health interventions.

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