Examples Of Trains Research Articles

Linear complementarity formulations for contact analysis and wear prediction in gears

This work presents linear complementarity based formulations for contact analysis and wear prediction in gear trains. Assuming steady motion of gears transmitting constant input torque without transmission errors, three sets of linear complementarity formulations are proposed, first for rigid gear teeth, second for gear teeth with skin compliance, and third for gear teeth with full compliance, the last two being new in linear complementarity literature. The developed formulations are used for contact analysis of two examples of gear trains, a pair of spur gears in mesh, and a planetary gear train. The accuracy of the method is tested by considering various time step sizes and stability of the formulations demonstrated for wide range of time steps. Contact forces between meshing teeth are calculated at a pre-defined set of points on the path of contact, and then wear is calculated on gear tooth flank using Archard’s wear equation. These wear calculations are compared with existing results in literature which demonstrate the applicability of the developed LC formulations. Future work is projected to include more state-of-art friction models and extension to 3D contact analysis in helical gear trains.

A connected driver advisory system framework for merging freight trains

This paper proposes an approach to facilitate smooth merging of freight trains into a stream of passenger trains with short headways, to help drivers better control freight trains and avoid red signals. An algorithm architecture is proposed for Driver Advisory Systems (DASs) to compute time/speed advice for freight train drivers. The framework includes four parts: buffer stairway prediction, freight train movement prediction, merging window detection and merging optimization. The basic idea is to predict the traffic state in the merging area regularly and find the feasible merging time window. Proper advice can be presented to freight train drivers and help them to merge smoothly, by comparing the freight train movement to the feasible merging window. The performance of the proposed algorithms is illustrated on examples of merging freight trains in the Meteren and Kijfhoek areas on the Dutch railway network. The experimental results show the efficiency and quality of the proposed algorithms on real world size problems.

Tolerance analysis of gear trains by static analogy

Assembly-level geometric errors such as backlash, center distance errors and shaft misalignments may adversely affect the operation of a gear train. The tolerance analysis method proposed in the paper estimates these errors from tolerance specifications on gears and mounting parts (shafts, bearings, housings). The problem is solved by analogy with an equivalent problem of force analysis: on a properly defined structure, external forces correspond to the assembly-level error, and calculated internal forces and support reactions provide the sensitivities of part tolerances on the total error. Previously developed for generic assemblies, the approach proves especially simple for gear systems compared to existing methods of tolerance analysis, as it relies upon structural analysis procedures that are customary in mechanical design. The method based on static analogy includes a two-level classification of geometric errors, which helps overcome the complexity of tolerance analysis problems for gearings. Two examples of gear trains of different types and configurations are presented to demonstrate the calculation procedure and verify its correctness by comparison with geometric considerations.

Uma Experiência Turística no Trem de Passageiros da Estrada de Ferro Vitória a Minas

Em razão de consecutivas decisões políticas e ações governamentais em âmbito nacional, a oferta de transporte ferroviário de passageiros no Brasil se concentra, principalmente, no transporte férreo urbano presente em algumas áreas metropolitanas populosas. Há raros exemplos de trens que transportam passageiros de longa distância e alguns poucos trens turísticos que operam trechos curtos e, nem sempre, tem frequência regular. Um dos trechos ferroviários que conta com trem de passageiros, diários e regulares é o da Estrada de Ferro Vitória a Minas, operado pela empresa Vale, que liga as capitais Vitória-ES e Belo Horizonte-MG. Este estudo constitui-se em uma pesquisa exploratóriadescritiva, que empregou a técnica de observação participante, para concretizar o objetivo de registrar as experiências de um passageiro-turista, vividas pelo pesquisador, ao realizar o referido percurso. Como resultado detectou-se que apesar do serviço de passageiros ser oferecido para atender moradores da região e constituir-se em um fator que promove o desenvolvimento regional, ele também apresenta características que podem ser aproveitadas por turistas e por operadoras turísticas.

Lntermodal transport development within the New Silk Road

The growth of trade flows between Asia and Europe results in growing container traffic between continents involved. Maritime transport dominates in cargo transport between China and Europe, but due to congestions in Chinese and European sea ports there is a need to develop the alternative transport routes, mainly railroad ones. It is a main goal of the new Chinese project Belt, One under the concept of New Silk Road. The purpose of the article is to analyze both the trade and transport flows between Asia, mainly China and Europe. In the article there are also presented the idea of the New Silk Road as well as the examples of container trains operated between China and Europe. Finally, author presents the role of Poland in development of rail con­nections under New Silk Road.

Power flow and efficiency analysis of multi-flow planetary gear trains

Power flow and efficiency analysis play an important role in the design of multi-flow planetary gear trains. Based on hypergraph and matrix operation, this paper proposes a new method to calculate gear speed ratio, velocity, torque and power. Systematic efficiency computation is carried out by following the power flow, and power loss equations on each node are derived via an approach based on self-rotation relative power. Power flow analysis and efficiency formulas are verified by two examples of multi-flow planetary gear trains. The proposed method significantly reduces the time required to establish the governing equations. Efficiency on each node can be calculated by following power flow, therefore making system efficiency calculation more accurate. Since power losses on certain nodes are dominant, parameter analysis is performed to analyze their influences.

Vibration analysis on multi-mesh gear-trains under combined deterministic and random excitations

In this paper, the vibration of a gear train with multi-meshes under both deterministic and random loads is investigated. The equation of motion is solved with stochastic Newmark algorithm and the responses of the displacements, including means and standard deviations, are obtained through numerical integration. The nonlinearity caused by the clearance between meshing teeth is treated with statistic linearization techniques. Examples of gear trains working under heavy load and light load are simulated and the result shows that the system behaves linearly under heavy load and nonlinearly with softening spring character under light load.

Specific mechanism of use-dependent channel block of calcium-permeable AMPA receptors provides activity-dependent inhibition of glutamatergic neurotransmission

This study examined the blocking action of the selective channel blocker of calcium-permeable (CP) AMPA receptors, N1-(1-phenylcyclohexyl)pentane-1,5-diaminium bromide (IEM-1925), on excitatory postsynaptic currents in rat neostriatal and cortical neurons and in fly neuromuscular junctions. In both preparations, the blocking of CP-AMPA receptor currents increased along with the stimulation frequency. The continuous presence of kainate, which activates AMPA receptors, in the external solution also caused an enhanced blocking effect. Likewise, decrease of the synaptic release by lowering calcium concentration resulted in significant reduction of the blocking action. The activity dependence of the block is explained using the guarded receptor model. The drug molecule can only bind if the channel is open. After the channel has closed, the drug molecule remains trapped inside. However, the trapped molecule slowly egresses from closed channels to the cytoplasm. The total block effect is determined by the equilibrium between accumulation of the drug in the open channels and relief from the closed channels. Therefore, the conditions that favour the open state result in enhanced inhibition. This significant finding reveals a new way to modulate CP-AMPAR-mediated transmission using a physiologically relevant approach. Moreover, it allows the involvement of CP-AMPARs in the physiological and pathological processes – such as high-frequency synaptic activity or increase of the steady-state glutamate concentration – to be examined.

Activity-Dependent Control of Neuronal Output by Local and Global Dendritic Spike Attenuation

Neurons possess elaborate dendritic arbors which receive and integrate excitatory synaptic signals. Individual dendritic subbranches exhibit local membrane potential supralinearities, termed dendritic spikes, which control transfer of local synaptic input to the soma. Here, we show that dendritic spikes in CA1 pyramidal cells are strongly regulated by specific types of prior input. While input in the linear range is without effect, supralinear input inhibits subsequent spikes, causing them to attenuate and ultimately fail due to dendritic Na(+) channel inactivation. This mechanism acts locally within the boundaries of the input branch. If an input is sufficiently strong to trigger axonal action potentials, their back-propagation into the dendritic tree causes a widespread global reduction in dendritic excitability which is prominent after firing patterns occurring in vivo. Together, these mechanisms control the capability of individual dendritic branches to trigger somatic action potential output. They are invoked at frequencies encountered during learning, and impose limits on the storage and retrieval rates of information encoded as branch excitability.

Coronal fast wave trains of the decimetric type IV radio event observed during the decay phase of the June 6, 2000 flare

The 22 min long decimetric type IV radio event observed during the decay phase of the June 6, 2000 flare simultaneously by the Brazilian Solar Spectroscope (BSS) and the Ondřejov radiospectrograph in frequency range 1200–4500 MHz has been analyzed. We have found that the characteristic periods of about 60 s belong to the long-period spectral component of the fast wave trains with a tadpole pattern in their wavelet power spectra. We have detected these trains in the whole frequency range 1200–4500 MHz. The behavior of individual wave trains at lower frequencies is different from that at higher frequencies. These individual wave trains have some common as well as different properties. In this paper, we focus on two examples of wave trains in a loop segment and the main statistical parameters in their wavelet power and global spectra are studied and discussed.

Duality between the kinematics of gear trains and the statics of beam systems

This paper provides geometric insight into the duality between the first-order kinematics of gear trains and the statics of beam systems. The two devices have inherent geometrical relationships that will allow the angular velocities of the gears in a gear train to be investigated from a knowledge of the forces acting on the beams of the dual beam system, and vice versa. The primary contribution of the paper is the application of this duality to obtain the dual beam system for a given compound planetary gear train, and vice versa. The paper develops a systematic procedure to transform between the first-order kinematics of a gear train and the statics of the dual beam system. This procedure provides a simple and intuitive approach to study the speed ratios of a planetary gear train and the force ratios of the dual beam system. The speed ratios are expressed in terms of kinematic coefficients, which are a function of the position of the input gear and provide insight into the geometry of the gear train. Two numerical examples of simple and compound planetary gear trains are presented to demonstrate the simplicity of the proposed approach. A third example is included to illustrate the systematic procedure to transform from a given beam system to a planetary gear train. The examples take advantage of the principle that the speed ratios for gearing are dual to the force ratios for beam systems, and vice versa.

Detection of spike patterns using pattern filtering, with applications to sleep replay in birdsong

Consolidation of memories during sleep may involve neuronal replay of daytime activity patterns. A precise replay phenomenon was observed in the song system nucleus RA. We developed statistical pattern filtering to investigate replay in HVc, where spiking activity is more variable. Long spike sequences during sleep were convolved with filters constructed from exemplar auditory spike sequences. Examining peaks in the filter responses, we found many examples of HVc spike trains with temporal patterns similar to the exemplars, confirming a replay phenomenon for HVc. Statistical pattern filtering has general utility for finding spike patterns when a referent pattern is known.

Solar-wind controlled pulsations at low latitudes

Past observations and present models of the solar-wind controlled dayside Pc 3-Pc 4 pulsations are reviewed. A year-long comparison between solar-wind parameters obtained from IMP-8 and micropulsation measurements made at L'Aquila is presented. This study shows that at low latitudes the relationship between the two phenomena is more clear than at high latitudes. In particular, in agreement with the upstream-wave source mechanism, different frequency regimes of pulsations can be related to different regions of the high-velocity streams. Some examples of spectacular wave trains, with unusual amplitude and period, occurred during the strong geomagnetic storm of March 13, 1989 are also presented.

An improved graphical method for pattern recognition from spike trains of spontaneously active neurons.

Spontaneous activity and rhythmical oscillations are common features of large neuronal networks in mammals. Detection of repetitive spike patterns or pacemaker activity during electrophysiological recording of spontaneous action potentials from single neurons can be difficult if a "noisy" background is present. This paper describes an improved method for an online spike train analysis based on joint interval histograms (JIH, Rodiek et al. 1962). By means of higher ordered JIH the discrimination of spike patterns with repetitive bursting activity or oscillations is possible even when randomly distributed action potentials appear. Examples of simulated spike trains and those recorded from cultured hippocampal neurons are presented.

The height of large ionospheric irregularities

The amplitude of the 54 Mc/s signal from the satellite Transit 4A was recorded at two stations, 100 km apart, from March to August 1964. The time difference between observing similar fluctuations in the fading period at the two stations was used to determine the height of ionospheric irregularities. 44 irregularities were observed, predominantly between the hours 0800 and 1800 local time, at heights from 180 to 750 km. The horizontal sizes varied from 75 to 520 km. The denser irregularities occurred only near the peak of the ionosphere, between 250 and 400 km, so that the mean percentage density fluctuations were approximately the same at all heights. Two examples of trains of irregularities were found, in which the irregularities lay on a straight line tilted down to the south at an angle of about 15 degrees. There was some evidence that the individual irregularities were also tilted down to the south by this amount.