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1
Li, Weixi, Geordie S. Roscoe, Zhipeng Zhang, M. Rapik Saat, and Christopher P. L. Barkan. "Quantitative Analysis of the Derailment Characteristics of Loaded and Empty Unit Trains." Transportation Research Record: Journal of the Transportation Research Board 2672, no. 10 (November 29, 2018): 156–65. http://dx.doi.org/10.1177/0361198118810780.
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Operation of unit trains has grown substantially over the past half century owing to their ability to provide economic and efficient transportation of bulk products. Although various aspects of train safety have been studied, there has been limited research examining the effect of train loading conditions on derailment occurrence, cause and severity. An algorithm was developed to identify derailments of loaded and empty unit trains on mainlines and sidings recorded in the Federal Railroad Administration database. A dataset of these accidents for the 15-year period of 2001–2015 was developed and analyzed. The frequency of derailments for both loaded and empty unit trains declined by more than 50%. The average number of cars derailed per accident fluctuated for both loading conditions, but showed no particular trend. Approximately five times more loaded unit train derailments were recorded in the database than empty unit trains, but in the absence of specific unit train traffic data, inferences about rates are not possible. Loaded unit trains were more than four times heavier than empty unit trains and loaded train derailments tended to involve more cars than empty trains. The distribution of derailment causes differed for loaded and empty unit trains. Loaded trains most frequently derailed because of broken rails and welds, while the leading cause of empty train derailments was obstructions, in particular severe weather. Over 90% of the derailments of loaded and empty unit trains considered in this study occurred on mainline tracks, and the distribution of causes differed between mainline and siding tracks.
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Liu, Xiang. "Risk Comparison of Transporting Hazardous Materials in Unit Trains versus Mixed Trains." Transportation Research Record: Journal of the Transportation Research Board 2608, no. 1 (January 2017): 134–42. http://dx.doi.org/10.3141/2608-15.
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This research developed an integrated, generalized risk analysis methodology for comparing hazardous materials transportation risk in unit trains versus mixed trains for the same amount of traffic demand. The risk methodology accounted for FRA track class, method of operation, annual traffic density, train length, speed, point of derailment, the number and placement of tank cars in a train, tank car placement, tank car safety design, and population density along the rail line. With these inputs, the methodology estimates train derailment rate, the probability of tank car derailment and release, and release consequence by train configuration. The analysis showed that tank car positions could affect the risk comparison between unit trains and mixed trains in transporting hazardous materials. In particular, if all tank cars were in positions that were least prone to derailment, distributing tank cars to many unit trains could reduce the overall risk. Otherwise, consolidating tank cars into unit trains could lead to a lower risk. The methodology has been implemented in a computer-aided decision support tool that automatically calculates the risk values for various track, rolling stock, and operational characteristics.
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Zaytsev, A. A., and P. S. Troitskiy. "Freight Electric Multiple-Unit Trains as an Alternative to Locomotive Traction. Comparison and Analysis." World of Transport and Transportation 17, no. 3 (September 27, 2019): 72–81. http://dx.doi.org/10.30932/1992-3252-2019-17-3-72-81.
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The advantages of introduction of modular freight electric trains in comparison with freight trains using locomotive traction are described, the main prerequisites for introduction of a distributed multiple-unit freight traction are indicated. The results of comparison of the technology of transportation with traction by locomotive situated at the head of the train and by the train with self-propelled coaches, as well as the analysis of traction calculations of two types of trains are suggested. The international experience of developing freight trains with distributed traction is described.The main directions of implementation of the concept of accelerating freight transportation on the territory of the Russian Federation are noted. It is concluded that in modern conditions, when speed becomes an economic category, it is necessary to create rolling stock of a new generation (wheel and magnetic suspension), and introduction of freight trains with distributed traction becomes extremely relevant.
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Jiang, Zhibin, Yuyan Tan, and Özgür Yalçınkaya. "Scheduling Additional Train Unit Services on Rail Transit Lines." Mathematical Problems in Engineering 2014 (2014): 1–13. http://dx.doi.org/10.1155/2014/954356.
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This paper deals with the problem of scheduling additional train unit (TU) services in a double parallel rail transit line, and a mixed integer programming (MIP) model is formulated for integration strategies of new trains connected by TUs with the objective of obtaining higher frequencies in some special sections and special time periods due to mass passenger volumes. We took timetable scheduling and TUs scheduling as an integrated optimization model with two objectives: minimizing travel times of additional trains and minimizing shifts of initial trains. We illustrated our model using computational experiments drawn from the real rail transit line 16 in Shanghai and reached results which show that rail transit agencies can obtain a reasonable new timetable for different managerial goals in a matter of seconds, so the model is well suited to be used in daily operations.
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Arshintsev, Dmitriy, Sergey Tolmachev, and Alexander Brzhezovskiy. "The development of service conditions for special-purpose cars based on the results of full-scale tests." Proceedings of Petersburg Transport University, no. 3 (September 20, 2018): 455–62. http://dx.doi.org/10.20295/1815-588x-2018-3-455-462.
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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.
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Bowman, D. M., J. J. Eggermont, and G. M. Smith. "Effect of stimulation on burst firing in cat primary auditory cortex." Journal of Neurophysiology 74, no. 5 (November 1, 1995): 1841–55. http://dx.doi.org/10.1152/jn.1995.74.5.1841.
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1. Neural activity was recorded extracellularly with two independent microelectrodes aligned in parallel and advanced perpendicular to isofrequency sheets in cat primary auditory cortex. Multiunit activity was separated into single-unit spike trains using a maximum variance spike sorting algorithm. Only units that demonstrated a high quality of sorting and a minimum spontaneous firing rate of 0.2 spikes/s were considered for analysis. The primary aim of this study was to describe the effect of periodic click train and broadband noise stimulation on short-time-scale (< or = 50 ms) bursts in the spike trains of single auditory cortical units and to determine whether stimulation influenced the occurrence, spike count, and/or temporal structure of burst firing relative to a spontaneous baseline. 2. Extracellular recordings were made in 20 juvenile and adult cats from 69 single auditory cortical units during click train stimulation and silence, and from 30 single units during noise stimulation and in silence. In an additional 15 single units the effect of both click train and noise stimulation was investigated. The incidence, spike count, and temporal structure of short-time-scale burst firing in the first 100 ms following stimulus presentation was compared with burst firing in the period starting 500 ms after stimulus presentation and with spontaneous burst firing. In addition, the serial dependence of interspike intervals within a burst was tested during periods of stimulation. 3. Burst firing was present in the stimulation, poststimulation, and spontaneous conditions. Longer bursts (consisting of > or = 3 spikes) were more commonly observed in the poststimulation and spontaneous conditions than in the stimulation condition. This effect was most pronounced during click stimulation. A period of elevated firing activity was present in a subset of units 0.5-1.5 s after stimulus presentation, indicating prolonged effects of stimulation on single-unit firing behavior. 4. For both stimuli, the proportion of single-unit responses composed of bursts was significantly greater in poststimulation and spontaneous periods than during stimulation. Burst rate was higher in post-click-train stimulation and spontaneous periods than during periods of click stimulation. The isolated spike rate was significantly higher during periods of noise and click stimulation than in the poststimulation and spontaneous periods. 5. An examination of the autocorrelograms and higher-order interspike interval histograms of single-unit responses during click train stimulation indicated that 25% of single-unit spike trains contained an excess of brief first-order intervals and 14% of spike trains contained a shortage of long higher-order interspike intervals relative to a spontaneous baseline. During noise stimulation, 10% of single-unit responses contained an excess of short intervals relative to baseline. Interspike intervals of short-duration bursts were not serially dependent during periods of stimulation. 6. A comparison of the autocorrelograms and higher-order interval histograms of single-unit responses in the poststimulation and spontaneous conditions indicated that 20% of single-unit spike trains contained an excess of short first-, second-, and third-order intervals following stimulation. This subgroups of single units could not be distinguished on the basis of the age of the animal or the depth at which the recording was made. 7. The low incidence of burst firing during stimulation opposes the view that bursts serve as a mechanism to emphasize or amplify particular stimulus-related responses in the presence of ongoing spontaneous activity in the primary auditory cortex. Moreover, there is little evidence to support the notion that brief bursts represent neural codes, because intraburst intervals are not serially dependent. It is suggested that pyramidal burst firing may be an effective way to evoke postsynaptic firing in inhibitory interneurons and subsequ
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Glushko, Marat Ivanovich, Nadezhda Grigorievna Fetisova, and Artyom Razhapovich Galiullin. "Brake condition monitoring in multiple unit trains." Transport of the Urals, no. 1 (2016): 86–87. http://dx.doi.org/10.20291/1815-9400-2016-1-86-87.
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Bomford, John P. "A PSYCHIATRIC UNIT TRAINS FOR CRISIS INTERVENTION." Australian Occupational Therapy Journal 23, no. 2 (August 27, 2010): 70–75. http://dx.doi.org/10.1111/j.1440-1630.1976.tb01046.x.
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Wilkinson, D. T. "Electric Braking Performance of Multiple-Unit Trains." Proceedings of the Institution of Mechanical Engineers, Part D: Transport Engineering 199, no. 4 (October 1985): 309–16. http://dx.doi.org/10.1243/pime_proc_1985_199_171_01.
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The paper describes the many interrelationships of the various factors and types of braking techniques including the partially contradictory relationship between maximizing the use of the electric braking effort capability and maximizing the electrical regeneration capability and in the frequently misunderstood terms of maximum demand and peak demand. Various braking techniques from the past, present and looking towards the future are described which minimize the overall energy consumption and thus the operating costs of an electric railway system.
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Bedenbaugh, Purvis, and George L. Gerstein. "Multiunit Normalized Cross Correlation Differs from the Average Single-Unit Normalized Correlation." Neural Computation 9, no. 6 (August 1, 1997): 1265–75. http://dx.doi.org/10.1162/neco.1997.9.6.1265.
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As the technology for simultaneously recording from many brain locations becomes more available, more and more laboratories are measuring the cross-correlation between single-neuron spike trains, and between composite spike trains derived from several undiscriminated cells recorded on a single electrode (multiunit clusters). The relationship between single-unit correlations and multiunit cluster correlations has not yet been fully explored. We calculated the normalized cross-correlation (NCC) between single unit spike trains and between small clusters of units recorded in the rat somatosensory cortex. The NCC between small clusters of units was larger than the NCC between single units. To understand this result, we investigated the scaling of the NCC with the number of units in a cluster. Multiunit cross-correlation can be a more sensitive detector of neuronal relationship than single-unit cross-correlation. However, changes in multiunit cross-correlation are difficult to interpret uniquely because they depend on the number of cells recorded on each electrode and because they can arise from changes in the correlation between cells recorded on a single electrode or from changes in the correlation between cells recorded on two electrodes.
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Tolliver, Denver, and Pan Lu. "Forecasting Class I Railroad Fuel Consumption by Train Type." Transportation Research Record: Journal of the Transportation Research Board 2674, no. 2 (February 2020): 284–90. http://dx.doi.org/10.1177/0361198120906420.
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Fuel efficiency is an important consideration in evaluating public-sector investments in multimodal corridors. Two approaches are typically used in corridor studies to forecast railroad diesel fuel consumption: (1) system-average efficiency factors, and (2) detailed analytical estimates derived from train performance calculators. The former method is easy to apply but may not be reflective of the actual mix of trains used. The second method is data- and time-intensive and can only be effectively implemented with specialized software that is not publicly available. An intermediate method is introduced in this paper which allows distinctions among the types of trains that might be utilized in a corridor (e.g., unit, way, and through). A model is estimated from publicly available data that has excellent statistical properties and quantifies the absolute and relative fuel efficiencies of train options. The analysis demonstrates that using system-average fuel consumption factors may significantly understate railroad fuel economy when traffic moves in unit trains instead of mixed train service. The new method offers greater accuracy than system-average comparisons yet is much less data-intensive than train performance calculators or analytical methods.
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Kalinin, N. P., and M. Yu Obukhov. "Increasing the energy efficiency of an electric train by installing electric energy storage units." Proceedings of Petersburg Transport University 17, no. 4 (December 2020): 449–64. http://dx.doi.org/10.20295/1815-588x-2020-4-449-464.
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Objective: To increase the energy effi ciency of the Russian multi-unit rolling stock of railways by installing electric energy storage devices. Methods: The goal is achieved by applying integrated approach method to the problem of multi-unit rolling stock energy efficiency, with focus on the practical signifi cance and economic feasibility of the results. Results: The solutions produced can serve as a basic concept for the modernization of domestic rolling stock. Practical importance: Concepts of an electric train with electric energy storage units based on Russian electric trains have been developed in order to increase their energy efficiency.
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Wang, Yuqiang, Yuguang Wei, Hua Shi, Xinyu Liu, Liyuan Feng, and Pan Shang. "The unit train make-up scheme for loaded direction in the heavy haul railway." Smart and Resilient Transport 1, no. 1 (May 14, 2019): 30–44. http://dx.doi.org/10.1108/srt-07-2019-0005.
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Purpose The purpose of this paper is to study the unit train make-up scheme for loaded direction in the heavy haul railway. Design/methodology/approach A 0-1 nonlinear integer programming model with the aim of minimizing the idling period between actual train arrival time and expected train arrival time for all loaded unit trains are proposed. Findings The proposed model is applied into a case study based on Daqin heavy haul railway. Results show that the proposed model can offer operators an optimal unit train make-up scheme for loaded direction in heavy haul railway. Originality/value The proposed model can offer operators an optimal unit train make-up scheme for loaded direction in heavy haul railway.
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Eggermont, J. J., and G. M. Smith. "Synchrony between single-unit activity and local field potentials in relation to periodicity coding in primary auditory cortex." Journal of Neurophysiology 73, no. 1 (January 1, 1995): 227–45. http://dx.doi.org/10.1152/jn.1995.73.1.227.
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1. We recorded responses from 136 single units and the corresponding local field potentials (LFPs) from the same electrode at 44 positions in the primary auditory cortex of 25 juvenile, ketamine-anesthetized cats in response to periodic click trains with click repetition rates between 1 and 32 Hz; to Poisson-distributed click trains with an average click rate of 4 Hz; and under spontaneous conditions. The aim of the study is to evaluate the synchrony between LFPs and single-unit responses, to compare their coding of periodic stimuli, and to elucidate mechanisms that limit this periodicity coding in primary auditory cortex. 2. We obtained averaged LFPs either as click-triggered averages, the classical evoked potentials, or as spike-triggered averages. We quantified LFPs by initial negative peak-to-positive peak amplitude. In addition, we obtained trigger events from negativegoing level crossings (at approximately 2 SD below the mean) of the 100-Hz low-pass electrode signal. We analyzed these LFP triggers similarly to single-unit spikes. 3. The average ratio of the LFP amplitude in response to the second click in a train and the LFP amplitude to the first click as a function of click rate was low-pass with a slight resonance at approximately 10 Hz, and, above that frequency, decreasing with a slope of approximately 24 dB/octave. We found the 50% point at approximately 16 Hz. In contrast, the LFP amplitude averaged over entire click trains was low-pass with a similar resonance but a high-frequency slope of 12 dB/octave and a 50% point at approximately 12 Hz. 4. The LFP amplitude for click repetition rates between 5 and 11 Hz often showed augmentation, i.e., the amplitude increased in response to the first few clicks in the train and thereafter decreased. This augmentation was paralleled by an increase in the probability of firing in single units simultaneously recorded on the same electrode. 5. We calculated temporal modulation transfer functions (tMTFs) for single-unit spikes and for LFP triggers. They were typically bandpass with a best modulating frequency of 10 Hz and similar shape for both single-unit spikes and LFP triggers. The tMTF per click, obtained by dividing the tMTF by the number of clicks in the train, was low-pass with a 50% cutoff frequency at approximately Hz, similar to that for the average LFP amplitude. 6. the close similarity of the tMTFs for single-unit spikes and LFP triggers suggests that single-unit tMTFs can be predicted from LFP level crossings.(ABSTRACT TRUNCATED AT 400 WORDS)
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Su, Huanyin, Wencong Tao, and Xinlei Hu. "A Line Planning Approach for High-Speed Rail Networks with Time-Dependent Demand and Capacity Constraints." Mathematical Problems in Engineering 2019 (March 17, 2019): 1–18. http://dx.doi.org/10.1155/2019/7509586.
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In high-speed rail networks, trains are operated with high speeds and high frequencies, which can satisfy passenger demand with different expected departure times. Given time-dependent demand, this paper proposes a line planning approach with capacity constraints for high-speed rail networks. In this paper, a bilevel optimization model is formulated and the constraints include track section capacity per unit time, train seat capacity, and the gap between the number of starting trains and that of ending trains at a station. In the upper level, the objective is to minimize train operational cost and passenger travel cost, and the decision variables include the line of each train, carriage composition of each train, train stop patterns, train start times, and train arrival and departure times at stops in the line plan. In the lower level, a schedule-based passenger assignment method, which assigns time-varying demand on trains with seat capacity constraints by simulating the ticket-booking process, is used to evaluate the line plan obtained in the upper level. A simulated annealing algorithm is developed to solve the model in which some strategies are designed to search for neighborhood solutions, including reducing train carriages, deleting trains, adding trains, increasing train carriages, and adjusting train start times. Finally, an application to the Chinese high-speed rail network is presented. The numerical results show that (i) the average time deviations between the expected departure times and the actual boarding times of passengers are within 30 min, (ii) the unserved passengers are less than 200, and (iii) the average load factors of trains are about 70%. Hence, line plan solutions meet time-dependent demand well and satisfy the capacity constraints for high-speed rail networks.
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Day, Scott J., and Manuel Hulliger. "Experimental Simulation of Cat Electromyogram: Evidence for Algebraic Summation of Motor-Unit Action-Potential Trains." Journal of Neurophysiology 86, no. 5 (November 1, 2001): 2144–58. http://dx.doi.org/10.1152/jn.2001.86.5.2144.
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Prompted by the observation that the slope of the relationship between average rectified electromyography (EMG) and the ensemble activation rate of a pool of motor units progressively decreased (showing a downward nonlinearity), an experimental study was carried out to test the widely held notion that the EMG is the simple algebraic sum of motor-unit action-potential trains. The experiments were performed on the cat soleus muscle under isometric conditions, using electrical stimulation of α-motor axons isolated in ventral root filaments. The EMG signals were simulated experimentally under conditions where the activation of nearly the entire pool of motor units or of subsets of motor units was completely controlled by the experimenter. Sets of individual motor units or of small groups of motor units were stimulated independently, using stimulation profiles that were strictly repeatable between trials. This permitted a rigorous quantitative comparison of EMGs that were recorded during combined activation of multiple motor filaments with EMGs that were synthesized from the algebraic summation of motor unit action potential trains generated by individual nerve filaments. These were recorded separately by individually stimulating the same filaments with the same activation profiles that were employed during combined stimulation. During combined activation of up to 10 motor filaments, experimentally recorded and computationally synthesized EMGs were virtually identical. This indicates that EMG signals indeed are the outcome of the simple algebraic summation of motor-unit action-potential trains generated by concurrently active motor units. For both recorded and synthesized EMGs, it was confirmed that EMG magnitude increased nonlinearly with the ensemble activation rate of a pool of motor units. The nonlinearity was largely abolished when EMG magnitude was estimated as the sum of rectified, instead of raw, motor-unit action-potential trains. This suggests that the downward nonlinearity in the EMG-ensemble activation rate relation is due to signal cancellation arising from the perfectly linear summation of positive and negative components of action-potential waveforms. The findings provide a much needed post hoc validation of the concept of EMG generation by strict algebraic summation of motor unit action potentials that is generally relied on in theoretical modeling studies of EMG and in EMG decomposition algorithms.
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Zhang, Jing, Hui Li, and Rong Hua Li. "Automatic Positioning Control System of Train." Advanced Materials Research 328-330 (September 2011): 1801–5. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1801.
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A type of automatic positioning control system of train has been introduced. The key element of system is based on induction radio communication technology. System is composed of four parts: ground control unit, communication unit, train control unit and external control part. The carrier of position produced by generator is amplified and sent to the coded flat cable. Then the signal is induced by antenna of train. Through control unit of train, the location of train will be gained. The location signal is sent out to PLC control part which will control some external equipment. It is especially for real-time address detecting online of subway or light rail trains during running. Several functions of automatic stop, positioning, opening, closing and others have been achieved in this control system.
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Lin, Jun Ting, Xiao Ming Wang, and Jian Wu Dang. "A New Collision Avoidance Strategy for Chinese Train Control System." Applied Mechanics and Materials 614 (September 2014): 179–83. http://dx.doi.org/10.4028/www.scientific.net/amm.614.179.
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There are still enormous amount of collision between trains even if comprehensive and complex technology, such as train control system, is extensively deployed in the infrastructure which should help to avoid such collisions. Experiences from aviation, maritime, and road transport systems have shown that the probability of collisions can be significantly reduced with collision avoidance systems basing on direct vehicle-to-vehicle communication on-board, which do hardly require infrastructure components. Additional Collision Avoidance System overlay Train Control System (CASOTCS) for Chinese railway, which is independent of the regular control mechanism, is provided in this paper. CASOTCS unit architecture and its key issues: position detection, direct train-to-train communication and collision surveillance resolution are also discussed. CASOTCS receives and evaluates the information broadcasted by other infinity trains, if a potential collision is detected, lead to collision alerts and avoidance resolution advisories. CASOTCS has the potential to increase safety and efficiency in the future, such as shorten the distance between trains.
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Lu, Chao, Leishan Zhou, Jinjin Tang, and Ran Chen. "Hierarchical framework for coordinate optimization of train timetable and electric motor train unit circulation plan." Advances in Mechanical Engineering 9, no. 7 (July 2017): 168781401770579. http://dx.doi.org/10.1177/1687814017705798.
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To meet the increasing demand for improving railway service quality while using the precious mobile resources reasonably and economically, this research proposes a hierarchical approach that integrates the model for constructing an efficient electric motor train unit circulation plan into the model for optimized timetable design without predefining timetable details. A simulated annealing algorithm for solving the timetabling (main) model is designed, in which the neighborhood system is pretreated. A special tree construction–based branch-and-bound algorithm is improved for solving the electric motor train unit circulation planning (sub)model. The results of the numerical experiment verify the effectiveness of the proposed method. Specifically, compared to the randomly generated initial solution, the optimal solution obtained by the proposed methods reduces the total travel time by 686 min and reduces the number of electric motor train units by 5. The number of electric motor train units needed by the proposed method is on average at least two less than the method that handles the problem in a sequential way. Railway operators can implement this approach for balancing the efficiency of timetable and the quality of electric motor train unit circulation plan within a reasonable computation time when scheduling trains in railways.
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Jackiewicz, Jacek. "Coupler force reduction method for multiple-unit trains using a new hierarchical control system." Railway Engineering Science 29, no. 2 (June 2021): 163–82. http://dx.doi.org/10.1007/s40534-021-00239-w.
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AbstractDuring traction and braking of multiple-unit trains, substantial longitudinal dynamic forces might occur in couplers due to the non-optimal distribution of traction and braking forces generated by self-propelled carriages. These dynamic forces might create shocks affecting the reduction of endurance of the weakest train structural components primarily. Thus, the overall operational safety of the train is also lowered. The purpose of the paper is to develop a new control system to supervise the activities related to the longitudinal dynamics of each train carriage in a multiple-unit train to reduce the longitudinal coupler forces acting during train traction and braking. The hierarchical structure of the control system consists of two levels. The first master level of control works like standard cruise control. However, the reduction of longitudinal coupler forces is achieved by applying a second level of slave control systems with a control configuration of feedback compensation.
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Kushnarev, Aleksey, Sergey Schitov, and Evgeniy Kuznetsov. "STUDY OF ROTATION KINEMATICS OF MULTI-LINK TRACTOR AND TRANSPORTATION UNITS WITH DEVICES CORRECTING THE WIDTH OF THE TRANSPORTATION CORRIDOR." Tekhnicheskiy servis mashin 1, no. 142 (January 2021): 65–71. http://dx.doi.org/10.22314/2618-8287-2020-59-1-65-71.
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The efficiency of the tractor-transport unit is largely due to its mobility, which in turn depends on many interrelated factors, such as handling, stability of movement and agility. One of the most important factors is the turnability, which ensures the ability of the tractor-transport unit to perform curved movement efficiently and safely. (Research purpose) The research purpose is in increasing the efficiency of the tractor-transport unit by using multi-link tractor trains. (Materials and methods) The main deterrent to the use of multi-link tractor trains in the Russian Federation is the increase in the overall width of the turn lane. The article presents a device that allows you to adjust the turning radius of the second trailer in order to optimize the width of the transport corridor. By changing the point of connection of the links in the turn, the movement is stabilized and the width of the transport corridor of the second link (trailer) is adjusted when moving. The article presents parameters of maneuverability of the tractor-transport train. (Results and discussion) The article presents the results of theoretical and experimental studies of the influence of the design and technological parameters of the proposed device on the maneuverability parameters of multi-link tractor-transport units. (Conclusions) The use of a towing-distributing device allows optimizing the width of the transport corridor of a multi-link tractor-transport unit by changing the turning radius of the second trailer.
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Binder-Macleod, S. A., and H. P. Clamann. "Force output of cat motor units stimulated with trains of linearly varying frequency." Journal of Neurophysiology 61, no. 1 (January 1, 1989): 208–17. http://dx.doi.org/10.1152/jn.1989.61.1.208.
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1. A relation between stimulation frequency and muscle force is usually determined with stimulus trains of constant frequency and described as a single-valued sigmoid curve. This relationship fails to explain a number of features of rate coding. 2. Single motor units were isolated in medial gastrocnemius or soleus muscles of cats deeply anesthetized with pentobarbital sodium. Motor units were classified as fast or slow. Each unit was stimulated with a train whose frequency varied linearly from less than 3 pulses per second (pps) to 20% above the unit's fusion frequency and back to about 3 pps with a period of 5 s. 3. All motor units showed a marked hysteresis during frequency-varying stimulation. A greater force was produced when frequency was decreasing than when it was increasing. The force output of each unit remained nearly maximal as stimulus frequency declined from its maximum to about one-half of the unit's fusion frequency; force rapidly declined with further decreases in frequency. The force-frequency relation could change with each trial as frequency increased but was highly reproducible when frequency decreased. This suggested a strategy by which central nervous system (CNS) control could maximize the force at any discharge rate and produce a predictable force-frequency relation. 4. Posttetanic potentiation, motor unit slowing, and a preload which causes a motor unit to operate on the negatively sloping portion of the length-tension curve may each contribute to the observed hysteresis under certain circumstances. None can explain why hysteresis was consistently seen in all motor units. A time-dependent rate of tension development and decay together with a catchlike property can account for all of the properties of hysteresis and appeared to be the primary cause of hysteresis in fully potentiated motor units.
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Dobretsov, Roman, Matvey Gubachev, Ivan Naletov, and Alexey Vasiliev. "On the way to driverless road-train: Digital technologies in modeling of movement, calculation and design of a road-train with hybrid propulsion unit." SHS Web of Conferences 44 (2018): 00030. http://dx.doi.org/10.1051/shsconf/20184400030.
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Today, road-trains are one of the most widely-spread and multi-tonnage transport vehicles on road arteries interconnecting countries and cities. The concept of hybrid road-trains mostly meets the widely-spread policy for stepping up the rates of exhaust gas emissions and reducing specific hydrocarbon fuel costs but only an intermediate link in the development of more significant and important design – a driverless road-train. This article considers active trailers and their models with different design options for heavy tractor truck propulsion unit drive. The influence of trailer link drive on turning has been studied in “Universal gear” software. Special attention has been given to an electrical drive of active semi-trailer wheels as the most advanced one at the present moment. We have obtained the data intended to be used in design of active trailer chassis and identified the weight and size characteristics of energy accumulators required for movement of a road-train with active trailer. The efficiency factor for different semitrailer drives has been analyzed and calculated, in particular: Low EF of electrical drive. The relevancy of active trailer concept including that for driverless road-trains has been determined on the basis of received data.
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Zamyshliaev, A. M., A. N. Ignatov, A. I. Kibzun, and E. O. Novozhilov. "On traffic safety incidents caused by intrusion of derailed freight cars into the operational space of an adjacent track." Dependability 18, no. 3 (September 5, 2018): 39–45. http://dx.doi.org/10.21683/1729-2646-2018-18-3-39-45.
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Aim.Derailments of rolling stock units (cars, locomotive units) of freight trains cause damage to roadbed and rolling stock, as well as possible loss of transported cargo. Of special interest are cases when derailed rolling stock units intrude into the operational space ofan adjacent track. This, for instance, happened in the case of the Moscow – Chișinșu train at the Bekasovo I – Nara line on May 20, 2014, when as a result of the derailment of freight cars with subsequent intrusion into the operational space of an adjacent track 6 people were killed as the result of collision with an opposing train. In some cases intruding units may collide with an opposing freight train, which may cause the death of that train’s crew and derailment of its cars, which in case of transportation of hazardous loads (e.g. oil and gasoline) may have catastrophic consequences. Intrusion into the operational space ofan adjacent track also interrupts the traffic in both directions. In this context, evaluating the probability of derailed cars intruding into the operational space of an adjacent track is extremely important in order to maintain the tolerable level of risk in railway transportation, while the aim of this paper is to construct functional dependences between the probability of derailed cars intruding into the operational space of an adjacent track and various factors.Methods. Probability theory and mathematical statistics methods were used: maximum likelihood method, logistic regression, probit regression, Cauchy regression.Results.For each of the groups of incidents: derailments due to faulty cars/locomotive units, derailments due to faulty track, using the classic binary choice model an estimation was constructed of the probability of at least one derailed freight car intruding into the operational space of an adjacent track. This estimation turned out to be dependent upon the train loading and number of derailed units. As the number of derailed units is a priori (before the derailment) unknown, it was suggested to construct the probability of intrusion by at least one derailed freight car into the operational space of an adjacent track using a parametric model of dependence between the average number of derailed units and various traffic factors. The resulting dependences were compared. A numerical example was examined.Conclusions.There is a significant direct correlation between the random values that characterize intrusion by at least one unit into the operational space of an adjacent track and the number of derailed freight train units. A direct dependence between the train loading and intrusion by derailed units into an adjacent track was established. In case of derailment due to faulty track, for loaded trains the probability of at least one derailed unit intruding into the operational space of an adjacent track is extremely high.
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Luo, Xiaolin, Tao Tang, Hongjie Liu, Lei Zhang, and Kaicheng Li. "An Adaptive Model Predictive Control System for Virtual Coupling in Metros." Actuators 10, no. 8 (August 1, 2021): 178. http://dx.doi.org/10.3390/act10080178.
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Virtual coupling (VC) is an emerging concept and hot research topic in railways, especially for metro systems. Several unit trains in VC drive with a desired minimum distance, and they, as a whole, are regarded as a single train. In this work, a distributed adaptive model predictive control (AMPC) system is proposed to coordinate the driving of each unit train in VC. To obtain the accurate parameters of train dynamics model in a time varying environment, an estimator of the train dynamics model is designed for each AMPC controller. A variable step descent algorithm along the negative gradient direction is adopted for each estimator, which steers the estimated values of the parameters to real ones. Simulations are conducted and the results are compared with both nominal model predictive control system and AMPC system with fixed steps in the literature. Our proposed AMPC system with variable step (AMPCVS) has better performances than other two systems. Results indicate that there is an improvement of the proposed AMPC system with variable steps system when compared with other two existed systems. A running process of VC in a whole inter-station is also simulated here. Experimental results show that the trains track the desired objective well.
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Li, Wen-Jun, and Xiao Feng. "Delay propagation cellular automata model based on max-plus algebra for robustness evaluations of non-periodic train operation plans." Modern Physics Letters B 34, no. 21 (May 26, 2020): 2050213. http://dx.doi.org/10.1142/s0217984920502139.
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Based on discrete-event dynamic system theory, train operation events in high-speed railway transportation systems are regarded as the basic elements of these dynamic systems. For non-periodic timetable railways in China, based on a max-plus algebra method, a delay propagation cellular automata model is proposed to evaluate the robustness of high-speed train operation plans. The cellular automata evolution rules that can reproduce the delay propagation state of trains mainly consider train safety headway constraints, passenger transfer constraints, and electric multiple unit (EMU) connection constraints. A simulation analysis of actual cases is performed. The simulation results show that the model can be used to evaluate the robustness of the train operation plan. The numerical results show that in the preparation of train operation plans, the proposed model can predict which trains have significant influences on delays in advance and improve the possibility of reducing the occurrence of delays to maintain high-quality service.
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Vittuari, Luca, Bogdan Pavkovic, Alexis Guinamard, Fabio Casciati, Matteo Zanzi, Antonio Ghetti, Lazar Berbakov, and Michele Vece. "Positioning Units for Critical Asset Tracking and Emergency Management." Advances in Science and Technology 101 (October 2016): 152–57. http://dx.doi.org/10.4028/www.scientific.net/ast.101.152.
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Motivated by the opportunity to develop industry pull applications and services for the European EGNOS and GALILEO satellite systems, within SPARTACUS project are being tested satellite based positioning units aided by small inertial navigation platforms. In particular, three different types of tracking units were designed and realized for: (i) freight trains tracing, (ii) relief goods distribution, and (iii) coordination of first responders. In order to improve the positioning accuracy in presence of several units installed on the same convoy, were developed software solutions based on two steps (low and high level) in order to allow the integration of information collected by the individual tracking unit and by the whole array of sensors.
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Lázaro, Mariano, David Lázaro, Edurne Cortabarria, and Daniel Alvear. "Innovations for smoke management in passenger trains." Journal of Fire Sciences 38, no. 2 (December 24, 2019): 194–211. http://dx.doi.org/10.1177/0734904119895775.
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Spanish manufacturer Construcciones y Auxiliar de Ferrocarriles developed an innovative alternative for compartmentation, based on a smoke extraction system, to guarantee safe conditions during evacuation processes in a passenger unit. To demonstrate its performance in a train unit, a real-scale experimental programme, supported by the application of fire computer modelling, was applied in a new Construcciones y Auxiliar de Ferrocarriles’ rolling stock. The new smoke exhaust system aims to extract the smoke generated during a fire in the passenger area by exhaust fans of the heating, ventilation, and air conditioning system, allowing the ingress of fresh exterior air in the lower part of the rear ends of the car. These key elements create an air flow that evacuates the smoke to prevent people from being exposed to it. Full-scale fire tests were developed in the train unit following the Australian standard AS 4391-1999. A fire of 140 kW was used, and the smoke was generated by a clean smoke machine. Measurement points included six thermocouple trees, 10 gas flow velocity probes and two GoPro HD video cameras (for the estimation of the visibility). The system performance was successful with the tenability criteria, since the value of visibility at the non-fire car was greater than 30 m and the temperature was lower than 30°C during all the tests at a height of 1.7 m above the floor. Experimental results were used to validate the computational model. The computational model results show a good accuracy compared with the tests.
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Nečas, Jan, Tomáš Mlčák, Jiří Zegzulka, and Roman Hrbáč. "Optimization of Drive Unit through Load Measurement." Applied Mechanics and Materials 260-261 (December 2012): 494–98. http://dx.doi.org/10.4028/www.scientific.net/amm.260-261.494.
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The basis is a device that contains tension sensor. The output of tension sensor is associated with the input control unit. The tension sensor is connected between the two loads. The sensing signal is processed using a PC measuring card with special software. The resulting device will be part of trains. Data sensing by this device will be transmitted from the PC to the control unit.
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Cho, Sungzoon, and James A. Reggia. "Learning Competition and Cooperation." Neural Computation 5, no. 2 (March 1993): 242–59. http://dx.doi.org/10.1162/neco.1993.5.2.242.
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Competitive activation mechanisms introduce competitive or inhibitory interactions between units through functional mechanisms instead of inhibitory connections. A unit receives input from another unit proportional to its own activation as well as to that of the sending unit and the connection strength between the two. This, plus the finite output from any unit, induces competition among units that receive activation from the same unit. Here we present a backpropagation learning rule for use with competitive activation mechanisms and show empirically how this learning rule successfully trains networks to perform an exclusive-OR task and a diagnosis task. In particular, networks trained by this learning rule are found to outperform standard backpropagation networks with novel patterns in the diagnosis problem. The ability of competitive networks to bring about context-sensitive competition and cooperation among a set of units proved to be crucial in diagnosing multiple disorders.
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Sandercock, T. G., J. A. Faulkner, J. W. Albers, and P. H. Abbrecht. "Single motor unit and fiber action potentials during fatigue." Journal of Applied Physiology 58, no. 4 (April 1, 1985): 1073–79. http://dx.doi.org/10.1152/jappl.1985.58.4.1073.
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Muscle fatigue is defined as a loss of tension development during constant stimulation. Although the relationship is not well documented, muscle fatigue has been inferred from electromyogram (EMG) signals. The purpose of this study was to determine the relationship between the amplitude and duration of single motor unit action potentials (MUAPs) and the loss of tension development (fatigue) in the medial gastrocnemius muscles of cats. Single motor units were fatigued by continuous stimulation at 10 or 80 Hz or with trains of 40-Hz stimuli. When motor units were stimulated at 10 Hz and with trains at 40 Hz (low frequency), tension declined and remained depressed during recovery. The changes in the MUAP correlated poorly with changes in tension. During and after stimulation at 80 Hz (high frequency), changes in the amplitude and duration of MUAPs correlated highly with changes in tension development. Since the EMG signal is dependent on a summation and cancellation of individual MUAPs, the EMG provides a reasonable estimate of high-frequency fatigue but an unreliable measure of low-frequency fatigue.
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Zhou, Xianping, Xiang Wei, Lin Ma, Fuwei Bai, and Hongwei Huang. "Research on emergency rescue technology and equipment for train operation accidents on a heavy-haul railway network." Transportation Safety and Environment 2, no. 4 (June 27, 2020): 260–70. http://dx.doi.org/10.1093/tse/tdaa014.
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Abstract Bridges, tunnels, cuttings and high subgrade account for a relatively large proportion in China's heavy-haul railway system, where 10 000 t of unit trains and 20 000 t of combined trains are in operation. When a train operation accident occurs, it can easily cause vehicle intrusions, slant-span lines, tipping and stacking. Based on the viewpoint of system engineering, rescue methods such as hoisting, lifting, pulling and overturning are integrated, according to the characteristics of heavy-haul transport and the construction practice of train accident rescue system. A scheme of technical research and equipment configuration relating to heavy-haul railway rescue in China is put forward based on the situation—embankment, bridge, tunnel (including cuttings), ramp and curve rescue, and so on—and three-dimensional finite-element modelling and calculation checks on the key components are carried out.
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Smolyaninov, Alexander Vasilyevich, and Konstantin Mikhaylovich Kolyasov. "Analysis of parameters and design solutions of bodies for innovative cars." Transport of the Urals, no. 4 (2020): 34–39. http://dx.doi.org/10.20291/1815-9400-2020-4-34-39.
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Development strategy of railway transport envisages operation of heavy-load trains on the following directions: Kuzbass — Far East (7100 tons), Kuzbass — South, Kuzbass — Centre, Kuzbass — North-West (9000 tons). But the existing rolling stock used for coal transportation doesn’t allow making up trains with the set weight on standard length of receivingand- departure tracks in direction of Far East. That is why the designers and manufacturers of open-box cars got a task to realize a design weight-bearing capacity in the unit of the rolling stock. The task has been solved by the increase of internal dimensions of open-box car body in existing limits by changing bodies design.
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Zeitler, Magteld, Pascal Fries, and Stan Gielen. "Assessing Neuronal Coherence with Single-Unit, Multi-Unit, and Local Field Potentials." Neural Computation 18, no. 9 (September 2006): 2256–81. http://dx.doi.org/10.1162/neco.2006.18.9.2256.
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The purpose of this study was to obtain a better understanding of neuronal responses to correlated input, in particular focusing on the aspect of synchronization of neuronal activity. The first aim was to obtain an analytical expression for the coherence between the output spike train and correlated input and for the coherence between output spike trains of neurons with correlated input. For Poisson neurons, we could derive that the peak of the coherence between the correlated input and multi-unit activity increases proportionally with the square root of the number of neurons in the multi-unit recording. The coherence between two typical multi-unit recordings (2 to 10 single units) with partially correlated input increases proportionally with the number of units in the multi-unit recordings. The second aim of this study was to investigate to what extent the amplitude and signal-to-noise ratio of the coherence between input and output varied for single-unit versus multi-unit activity and how they are affected by the duration of the recording. The same problem was addressed for the coherence between two single-unit spike series and between two multi-unit spike series. The analytical results for the Poisson neuron and numerical simulations for the conductance-based leaky integrate-and-fire neuron and for the conductance-based Hodgkin-Huxley neuron show that the expectation value of the coherence function does not increase for a longer duration of the recording. The only effect of a longer duration of the spike recording is a reduction of the noise in the coherence function. The results of analytical derivations and computer simulations for model neurons show that the coherence for multi-unit activity is larger than that for single-unit activity. This is in agreement with the results of experimental data obtained from monkey visual cortex (V4). Finally, we show that multitaper techniques greatly contribute to a more accurate estimate of the coherence by reducing the bias and variance in the coherence estimate.
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Lim, Kwang-kyun, and Gyeong-Cheol Yun. "Estimation of Unit Fare Based on Transport Costs for Sightseeing Trains." Journal of the Korean Society for Railway 21, no. 2 (March 31, 2018): 200–207. http://dx.doi.org/10.7782/jksr.2018.21.2.200.
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Su, Shuai, Tao Tang, and Xiang Li. "Driving strategy optimization for trains in subway systems." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 232, no. 2 (October 24, 2016): 369–83. http://dx.doi.org/10.1177/0954409716671546.
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Energy-efficient operation of trains in subway systems is regarded as one of the most effective strategies to cut down the operational cost. Most of the studies about the energy-efficient operation of trains aim to minimize the consumption of mechanical energy of trains. In this paper, an energy-efficient train control model is proposed under the practical billing system by introducing the traction efficiency. In addition, a numerical solution approach is presented to solve the energy-efficient driving strategy, which consists of the control sequences and the corresponding switching points. First, the authors analyze the energy-efficient control problem by applying the maximum principle, from which the energy-efficient control regime is proved to include the maximum acceleration, coasting, cruising with partial braking, and maximum braking. Second, the control sequences for one section are fully analyzed and an algorithm is presented to calculate the switching points with the energy consumption constraint. To obtain the solution to an interval with variable speed limits and gradients, the interval is divided into several sections, where the gradient and speed limit of each section are constants. A primary energy-efficient solution, which costs a longer trip time, is given. Then, energy units are assigned into multiple sections to shorten the trip time of the primary solution. Specifically, each energy unit is added into the selected section to achieve the maximum time reduction. Finally, the energy-efficient driving strategy at all sections will be obtained when the scheduled trip time of the interval is delivered. Some examples based on the practical data are conducted to illustrate that the proposed approach has a good potential on saving energy of trains.
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Hung, Chou P., Benjamin M. Ramsden, and Anna Wang Roe. "Weakly Modulated Spike Trains: Significance, Precision, and Correction for Sample Size." Journal of Neurophysiology 87, no. 5 (May 1, 2002): 2542–54. http://dx.doi.org/10.1152/jn.00420.2001.
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Many single-unit electrophysiological studies of visual cortex have investigated strong evoked responses to simple stimuli such as oriented gratings. Experiments involving other types of stimuli, such as natural scenes, higher-order features, and surface brightness, produce single-unit responses that are more difficult to interpret. Experiments with brightness, in particular, evoke single-unit responses that are typically weakly modulated. When the brightness is generated by a visual illusion such as the Cornsweet illusion, statistical tests are often necessary to distinguish true responses from baseline fluctuations. Here, using data collected from cat Areas 17 and 18 in response to real and illusory brightness stimuli, we provide a method for detecting and quantifying weak but significant periodic responses. By randomizing spike trains (via bootstrap methods), we provide confidence levels for response significance, permitting the evaluation of both weak and strong responses. We show that because of a strong dependence on total spike number, response significance can only be appropriately determined with randomized spike trains of similar spike number. Such randomizations can be performed for both stimulus-elicited and spontaneously occurring spike trains. By developing a method for generating randomized modulated spike trains (phase-restricted randomization) from actual recordings, we calculate upper and lower confidence limits of modulated spike trains and describe how measurement precision varies as a function of total spike count. Finally, using this randomization method, we describe how a correction function can be determined to correct for measurement bias introduced at low spike counts. These methods may also be useful in the study of small but potentially significant responses in other systems.
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Middleton, Jason W., André Longtin, Jan Benda, and Leonard Maler. "Postsynaptic Receptive Field Size and Spike Threshold Determine Encoding of High-Frequency Information Via Sensitivity to Synchronous Presynaptic Activity." Journal of Neurophysiology 101, no. 3 (March 2009): 1160–70. http://dx.doi.org/10.1152/jn.90814.2008.
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Parallel sensory streams carrying distinct information about various stimulus properties have been observed in several sensory systems, including the visual system. What remains unclear is why some of these streams differ in the size of their receptive fields (RFs). In the electrosensory system, neurons with large RFs have short-latency responses and are tuned to high-frequency inputs. Conversely, neurons with small RFs are low-frequency tuned and exhibit longer-latency responses. What principle underlies this organization? We show experimentally that synchronous electroreceptor afferent (P-unit) spike trains selectively encode high-frequency stimulus information from broadband signals. This finding relies on a comparison of stimulus-spike output coherence using output trains obtained by either summing pairs of recorded afferent spike trains or selecting synchronous spike trains based on coincidence within a small time window. We propose a physiologically realistic decoding mechanism, based on postsynaptic RF size and postsynaptic output rate normalization that tunes target pyramidal cells in different electrosensory maps to low- or high-frequency signal components. By driving realistic neuron models with experimentally obtained P-unit spike trains, we show that a small RF is matched with a postsynaptic integration regime leading to responses over a broad range of frequencies, and a large RF with a fluctuation-driven regime that requires synchronous presynaptic input and therefore selectively encodes higher frequencies, confirming recent experimental data. Thus our work reveals that the frequency content of a broadband stimulus extracted by pyramidal cells, from P-unit afferents, depends on the amount of feedforward convergence they receive.
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Rodriguez-Falces, Javier, Francesco Negro, and Dario Farina. "Correlation between discharge timings of pairs of motor units reveals the presence but not the proportion of common synaptic input to motor neurons." Journal of Neurophysiology 117, no. 4 (April 1, 2017): 1749–60. http://dx.doi.org/10.1152/jn.00497.2016.
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We investigated whether correlation measures derived from pairs of motor unit (MU) spike trains are reliable indicators of the degree of common synaptic input to motor neurons. Several 50-s isometric contractions of the biceps brachii muscle were performed at different target forces ranging from 10 to 30% of the maximal voluntary contraction relying on force feedback. Forty-eight pairs of MUs were examined at various force levels. Motor unit synchrony was assessed by cross-correlation analysis using three indexes: the output correlation as the peak of the cross-histogram (ρ) and the number of synchronous spikes per second (CIS) and per trigger (E). Individual analysis of MU pairs revealed that ρ, CIS, and E were most often positively associated with discharge rate (87, 85, and 76% of the MU pairs, respectively) and negatively with interspike interval variability (69, 65, and 62% of the MU pairs, respectively). Moreover, the behavior of synchronization indexes with discharge rate (and interspike interval variability) varied greatly among the MU pairs. These results were consistent with theoretical predictions, which showed that the output correlation between pairs of spike trains depends on the statistics of the input current and motor neuron intrinsic properties that differ for different motor neuron pairs. In conclusion, the synchronization between MU firing trains is necessarily caused by the (functional) common input to motor neurons, but it is not possible to infer the degree of shared common input to a pair of motor neurons on the basis of correlation measures of their output spike trains. NEW & NOTEWORTHY The strength of correlation between output spike trains is only poorly associated with the degree of common input to the population of motor neurons. The synchronization between motor unit firing trains is necessarily caused by the (functional) common input to motor neurons, but it is not possible to infer the degree of shared common input to a pair of motor neurons on the basis of correlation measures of their output spike trains.
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Matsuyama, Atsushi, Shinichiro Nakao, Daisuke Ono, Yoshiaki Miyazato, and Masashi Kashitani. "Two-dimensional quantitative visualization of isolator shock trains by rainbow schlieren deflectometry." EPJ Web of Conferences 180 (2018): 02063. http://dx.doi.org/10.1051/epjconf/201818002063.
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The rainbow schlieren deflectometry is effective in studying quantitatively the density fields in shock-containing free jets at high precision and high spatial resolution. However, there has been no practical application of rainbow schlieren deflectometry for shock trains in a confined duct. Therefore, in the present study, the rainbow schlieren deflectometry is applied to the flow field including a shock train in a constant-area duct where just upstream of the shock train the freestream Mach number is 1.34, the unit Reynolds number is 5.39 × 107 m-1, and the boundary layer displacement thickness is 0.149 mm. As a result, a two- dimensional density field of the shock train is for the first time quantitatively displayed and the fine structure of the shock train is illustrated as a color gradation representation.
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Thomas, C. K., and B. H. Ross. "Distinct Patterns of Motor Unit Behavior During Muscle Spasms in Spinal Cord Injured Subjects." Journal of Neurophysiology 77, no. 5 (May 1, 1997): 2847–50. http://dx.doi.org/10.1152/jn.1997.77.5.2847.
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Thomas, C. K. and B. H. Ross. Distinct patterns of motor unit behavior during muscle spasms in spinal cord injured subjects. J. Neurophysiol. 77: 2847–2850, 1997. Surface electromyograms (EMG) and force were recorded during repeated involuntary spasms of paralyzed triceps surae muscles of four men with chronic cervical spinal cord injury. The firing rates of 78 medial gastrocnemius (MG) motor units also were recorded intramuscularly with tungsten microelectrodes. Spasms typically involved a relatively rapid rise, then a more gradual fall in triceps surae EMG and torque. Motor unit firing rates either increased and then decreased with the spasm intensity (54%) or were relatively constant (26%), firing mainly at 2–10 Hz. The remaining units (20%) produced trains that included one or several doublets. Mean peak spasm firing rates were 18 ± 9 Hz (mean ± SD) for rate modulated units and 11 ± 10 Hz for units with little or no rate modulation. Some motor units fired at rates comparable with those recorded previously during maximum voluntary contractions performed by intact subjects. Others fired at rates below the minimum usually seen when normal units are first recruited (<6 Hz). Doublets (interspike interval <10 ms) often repeated every 123–333 ms, or were interspersed in trains firing at low steady rates (<11 Hz). This study shows that rate coding for many motor units appears to be similar whether descending motor input is intact or whether it has been reduced severely by spinal cord injury. In contrast, rate modulation in other units appears to depend mainly on voluntary motor commands.
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Aeles, J., L. A. Kelly, Y. Yoshitake, and A. G. Cresswell. "Fine-wire recordings of flexor hallucis brevis motor units up to maximal voluntary contraction reveal a flexible, nonrigid mechanism for force control." Journal of Neurophysiology 123, no. 5 (May 1, 2020): 1766–74. http://dx.doi.org/10.1152/jn.00023.2020.
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We recorded for the first time single motor unit action potential trains in the flexor hallucis brevis, a short toe muscle, over the full range of maximum voluntary contraction. Its motor units are recruited up to very high (98%) recruitment thresholds with a substantial range of discharge rates. We further show high variability with crossover of discharge rates as a function of recruitment threshold both between participants and between motor units within participants.
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Etkin, Dagmar Schmidt, Matthew Horn, and Andrew Wolford. "CBR-Spill RISK: Model to Calculate Crude-by-Rail Probabilities and Spill Volumes." International Oil Spill Conference Proceedings 2017, no. 1 (May 1, 2017): 3189–210. http://dx.doi.org/10.7901/2169-3358-2017.1.3189.
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ABSTRACT Abstract ID: 2017-142 – Evaluating risks from crude-by-rail (CBR) traffic for Environmental Impact Statements or contingency planning purposes requires quantification of both the probabilities and potential impacts from spill events. Despite publicity surrounding CBR accidents of the last few years, there are actually relatively few incidents to analyze for projecting spill probabilities and volumes. This paper presents a method (CBR-SpillRISK) to calculate spill probability and volumes for CBR risk evaluation using historical freight rail accident and tank car release data with adjustments specifically for CBR factors is presented. These factors include: CBR unit trains are operated differently from other freight trains with respect to maximum speed; CBR unit trains act differently with respect to lateral stability; operators plan to make capital improvements on rail lines; and a number of safety improvements for CBR have been, or will be, implemented due to federal and state regulations.
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Bawa, Parveen, and Blair Calancie. "Rate-coding of spinal motoneurons with high-frequency magnetic stimulation of human motor cortex." Canadian Journal of Physiology and Pharmacology 82, no. 8-9 (July 1, 2004): 740–48. http://dx.doi.org/10.1139/y04-069.
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Rate-coding in spinal motoneurons was studied using high-frequency magnetic stimulation of the human motor cortex. The subject made a weak contraction to cause rhythmic (i.e., tonic) discharge of a single motor unit in flexor (or extensor) carpi radialis or tibialis anterior, while the motor cortical representation of that muscle was stimulated with brief trains of pulses from a Pyramid stimulator (4 Magstim units connected by 3 BiStim modules). An "m@n" stimulus train consisted of m number of pulses (1–4), with an interpulse interval (IPI) of n ms (1–6). Peristimulus time histograms were constructed for each stimulus condition of a given motor unit, and related to the average rectified surface electromyography (EMG) from that muscle. Surface EMG responses showed markedly more facilitation than single-pulse stimulation, with increasing numbers of pulses in the train; responses also tended to increase in magnitude for the longer IPI values (4 and 6 ms) tested. Motor-unit response probability increased in a manner comparable to that of surface EMG. In particular, motoneurons frequently responded twice to a given stimulus train. In addition to recruitment of new motor units, the increased surface EMG responses were, in part, a direct consequence of short-term rate-coding within the tonically discharging motoneuron. Our results suggest that human corticomotoneurons are capable of reliably following high-frequency magnetic stimulation rates, and that this activity pattern is carried over to the spinal motoneuron, enabling it to discharge at extremely high rates for brief periods of time, a pattern known to be optimal for force generation at the onset of a muscle contraction.Key words: Human, single motor unit, repetitive transcranial magnetic stimulation, rate-coding, high-frequency stimulation, corticomotoneuron, peri-stimulus time histogram.
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Li, Xiao-Bai, Guang Chen, Zhe Wang, Xiao-Hui Xiong, Xi-Feng Liang, and Jing Yin. "Dynamic analysis of the flow fields around single- and double-unit trains." Journal of Wind Engineering and Industrial Aerodynamics 188 (May 2019): 136–50. http://dx.doi.org/10.1016/j.jweia.2019.02.015.
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Alexandrov, Alexander Ernstovich, Elena Nikolaevna Timukhina, and Igor Alexandrovich Kovalev. "Optimization model of the transportation process with the use of unit trains." Transport of the Urals, no. 4 (2017): 36–39. http://dx.doi.org/10.20291/1815-9400-2017-4-36-39.
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王, 大鹏. "Research on Safety Egress Evaluation for Railway Drivers of Multiple Unit Trains." Open Journal of Transportation Technologies 07, no. 04 (2018): 229–36. http://dx.doi.org/10.12677/ojtt.2018.74029.
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Dominic, S., and U. Maier. "Dynamic Modeling and Simulation of Compressor Trains for an Air Separation Unit." IFAC Proceedings Volumes 47, no. 3 (2014): 432–37. http://dx.doi.org/10.3182/20140824-6-za-1003.01510.
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Dominic, S., Y. A. W. Shardt, and S. X. Ding. "Economic Performance Indicator Based Optimization for the Air Separation Unit Compressor Trains." IFAC-PapersOnLine 48, no. 21 (2015): 858–63. http://dx.doi.org/10.1016/j.ifacol.2015.09.634.
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Malanda, Armando, Javier Navallas, Javier Rodriguez-Falces, Ignacio Rodriguez-Carreño, and Luis Gila. "Averaging methods for extracting representative waveforms from motor unit action potential trains." Journal of Electromyography and Kinesiology 25, no. 4 (August 2015): 581–95. http://dx.doi.org/10.1016/j.jelekin.2015.04.007.
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