Restricted by heat dissipation conditions, the switching frequency of the traction inverters for rail transit typically remains below 1 kHz, to prevent potential shortening of their service lifetime due to excessive switching losses in power devices. Inverter operation in the middle and high-frequency ranges results in a decrease in carrier ratio, leading to amplified output harmonics. This not only lowers output performance but also elevates peak current levels, intensifying power losses within the insulated-gate bipolar transistor (IGBT) and consequently undermining driving safety. Unlike existing modulation strategies to address low carrier ratios, which mostly focus on optimizing output performance while overlooking the suppression of IGBT power losses, this paper presents a multi-objective optimization modulation strategy for traction inverters under five-division frequency. This strategy aims to maintain a low weighted total harmonic distortion (WTHD) in the inverter output while reducing total power losses. Firstly, numerical and phase relationships between the output voltage and current were established based on the inverter load model. A precise discrete calculation model for IGBT power losses was developed based on the data manual provided by the device manufacturer, leveraging the power loss generation mechanism. Subsequently, the switching angles were solved under the premise of ensuring the fundamental amplitude of inverter output voltages aligned with the reference level, to enable multi-objective optimization modulation for inverters, including both inverter output current harmonics and power losses as optimization objectives. Simulation results indicate that within the operating range, the proposed optimization modulation strategy significantly reduced IGBT power losses and remained superior output performance compared to traditional strategies.
Binary classification is one of the important tasks in machine learning, with wide applications in various fields, including agriculture and food processing. This study compares the performance of the classical Support Vector Machine (SVM) and Quantum Support Vector Machine (QSVM) in wheat grain classification, focusing on accuracy, precision, recall, F1-score, and Area Under the Curve (AUC). The wheat grain dataset consists of physical features relevant to distinguish between two types of grains. The analysis results show that QSVM significantly outperforms classical SVM in all measured metrics, with higher accuracy and a better balance between precision and recall. The superiority of QSVM can be attributed to its ability to handle complex feature interactions and accelerate the training process through quantum algorithms. These findings demonstrate the potential of QSVM as a more effective model for binary classification applications. However, factors such as implementation complexity and availability of quantum computing resources need to be considered. This study provides valuable insights for the development of more efficient classification methods in the context of agriculture and other related fields.Keywords: Quantum Machine Learning, Quantum Support Vector Machine, Classification, Seeds
Introduction. The formation of an overarching network of nodal freight multimodal transport and logistics centres in the Russian Federation and organisation of high-speed freight traffic on schedule on its basis requires the development of science-based proposals for the creation or modernisation of the corresponding regional transport and logistics infrastructure. One of the most important tasks in the implementation of this project in the context of limited investment resources is the correct justification of the number and choice of locations for the transport and logistics centres of the overarching network in the Russian Federation, as well as the locations of transport and logistics centres in the constituent entities of the Russian Federation.Materials and methods. This article provides an evaluation analysis of the classical methods for finding optimal centres on a plane and some construction of mathematical quantitative models for the optimal placement of transport and logistics facilities.Results. According to the evaluation analysis, the authors have drafted a scientifically based concept of a systematic approach to the issues of rational design and placement of elements of transport and logistics infrastructure, in particular, the overarching network of nodal freight multimodal transport and logistics centres, as part of a new highly efficient transport and logistics infrastructure of the Russian Federation and its international transport corridors.Discussion and conclusion. The obtained results of the study can be used for scientifically based decision-making in investment projects related to the development of transport and logistics infrastructure at both regional and federal levels: substantiation of locations and technological capacities of transport and logistics infrastructure facilities; determining the need for the development of objects of the regional transport and logistics infrastructure, while eliminating their bottlenecks; implementation of a phased set of measures to modernise the existing terminal and logistics complex.
The article deals with a FEA results comparison of an open source FEM software CODE_ASTER with a commercial software SolidWorks Simulation and Abaqus. The problem of a statically loaded spherical cap is solved. Result evaluation is aimed at loss of stability, i.e. limit load (equilibrium curve) when loss of stability occurs and its corresponding shape of deformation. The response of the structure is described by a load-deflection curve of a top of a spherical cap in axial direction.
Railroad engineering and operation, Industrial engineering. Management engineering
Focus on the communication delay between the master and slave control locomotive, a detailed longitudinal dynamic simulation model considering the communication delay was established based on the multi-body dynamics theory. The influence of communication delay on longitudinal impulse of train during cycle braking on 12‰ heavy and long descending grade was simulated. Furthermore, the analysis of influence of communication delay on longitudinal impulse under different dynamic braking forces were completed. The simulation results indicated that both the longitudinal tractive force and pressing force increased with the increase of the communication delay, and the position of the maximum pressing force moved towards the train tail as the delay increased. Moreover, the communication delay had a significant effect on the negative acceleration of the vehicles. For the slave control locomotive, the negative accelerations increased with the increase of delays. For the other vehicles, the change of the delays would cause the fluctuation of negative accelerations. Furthermore, the effects of communication delay on longitudinal impulse were in coincide under different dynamic braking forces in air brake process. In air brake release process, the smaller the dynamic braking force was applied, the more significant effect of communication delay on longitudinal impulse exhibits.
Článek je věnovaný problematice záchranných a likvidačních prací složek integrovaného záchranného systému při reálné dopravní nehodě bez přítomnosti nebezpečných látek. V dnešní době se stále častěji setkáváme s mimořádnými událostmi různého charakteru, kdy významnou část zahrnují právě dopravní nehody. Teoretické i praktické poznatky ukazují, že zajištění požadované úrovně spolupráce záchranných složek může přispět ke snížení ztrát na lidských životech a snížení poškození zdraví účastníků zasažených mimořádnou událostí. Cílem článku je simulace společného zásahu složek integrovaného záchranného systému při reálné dopravní nehodě. K dosažení uvedeného cíle je použita síťová analýza, konkrétně metoda kritické cesty, která představuje sled vzájemně závislých činností s nejmenší časovou rezervou. Získané výsledky demonstrují jednu z možných variant optimalizace zkoumané činnosti složek integrovaného záchranného systému při řešení dopravní nehody.
Railroad engineering and operation, Industrial engineering. Management engineering
When the maglev train runs into the tunnel at a certain speed, it will produce the initial compression wave, which will propagate towards the tunnel exit at the local sound speed, and radiate to the surrounding at the tunnel exit to form the micro pressure wave. When the micro pressure wave is large enough, it will produce the sound explosion, which will cause serious harm to the environment, and the micro pressure wave at the entrance is closely related to the initial compression wave. Based on the three-dimensional compressible unsteady turbulent flow Reynolds averaged Navier Stokes equation and SST K - ω two equation turbulent flow model, the air flow and initial compression wave caused by maglev train entering the tunnel were numerically simulated by using the fi nite volume method and overlapping grid technique. The results showed that the initial compression wave had three-dimensional characteristics in the process of the train entering the tunnel, and after a certain distance, it became one-dimensional plane wave; secondly, at the same height, the closer to the car body, the greater the change of the compression wave, the closer to the car body and the closer to the ground, the greater the change of the compression wave, while the change of the initial compression wave far away from the car body was basically the same; The maximum pressure gradient of initial compression wave is approximately proportional to the third power of train speed.
Abstract Cab signaling apparatus is the critical equipment for ground-vehicle communication in electrified railways. With the rapid development of high-speed and heavy-haul railways, the immunity to unbalanced traction current interference for cab signaling apparatus in the onboard train control system is increasingly demanded. This paper analyzes the interference coupling mechanism of the ZPW-2000 track circuit. Based on electromagnetic field theory and the actual working parameters, a calculation model is established to complete the quantitative research of the cab signal induction process and traction current interference. Then, a finite element model is built to simulate the process. The simulation results under the signal frequency, fundamental and harmonic interference are all consistent with the theoretical calculation results. The practical measurement data verify the coupling relationship between cab signal inductive voltage and rail current. Finally, an indirect immunity test method applying this relation for the cab signals is proposed, and the voltage indexes of the disturbance sources are determined, i.e., the test limits. The results provide an accurate quantitative basis for the cab signaling research and design of the immunity test platform; besides, the proposed indirect test method can simplify the test configuration and improve test efficiency.
Abstract Three-dimensional compressible flow simulations were conducted to develop a Hyperloop pod. The novelty is the usage of Gamma transition model, in which the transition from laminar to turbulent flow can be predicted. First, a mesh dependency study was undertaken, showing second-order convergence with respect to the mesh refinement. Second, an aerodynamic analysis for two designs, short and optimized, was conducted with the traveling speed 125 m/s at the system pressure 0.15 bar. The concept of the short model was to delay the transition to decrease the frictional drag; meanwhile that of the optimized design was to minimize the pressure drag by decreasing the frontal area and introduce the transition more toward the front of the pod. The computed results show that the transition of the short model occurred more on the rear side due to the pod shape, which resulted in 8% smaller frictional drag coefficient than that for the optimized model. The pressure drag for the optimized design was 24% smaller than that for the short design, half of which is due to the decrease in the frontal area, and the other half is due to the smoothed rear-end shape. The total drag for the optimized model was 14% smaller than that for the short model. Finally, the influence of the system pressure was investigated. As the system pressure and the Reynolds number increase, the frictional drag coefficient increases, and the transition point moves toward the front, which are the typical phenomena observed in the transition regime.
In order to predict the remaining life of electronic products of rail transit, trial test of ccelerated life test (ALT) was designed and implemented for designing scheme of ALT effectively. According to the operating environmental characteristics of products and step stress implementing method of reliability development test, trial tests of temperature, humidity and vibration were designed. Limit stress level of temperature, humidity and vibration were determined by applying trial test, providing reference and guideline for design of ALT.
Referring to the particular features of mine transportation operation, which was being scheduled, organized and closed, put forward the operation organization model and external interface of autonomous mine haulage system, and the key points in the system design was sorted out. On this basis, the system architecture of autonomous open-pit mine haulage system was proposed as being composed of ground management and monitoring subsystem, vehicle mounted automatic driving subsystem and data communication subsystem, and the function requirements for each subsystem under the architecture were allocated. The operation scenarios of the autonomous mining haulage system were illuminated. The extension of the basic ideas and system architecture of the autonomous open-pit mine haulage system to the similar application field was also prospected.
In order to research the influence of short circuit fault for metro train traction system on safety performance of the power net, the detailed mathematical model was derived for the short circuit fault of metro in the traction line. Combining with the practical parameters of a subway, simulation analysis of short circuit of filter reactor and traction inverter in metro train was completed with MATLAB. The influence of the fault location on the short circuit current and its change rate was revealed. The simulation results could provide power system security assessment data for the metro companies.
In order to conduct a rapid assessment of product life, the effectiveness and applicability for life prediction based on reliability simulation method was discussed. Taking a vehicle-carried processor as research object, the weaknesses of thermal design and vibration design were exposed and the average life of 4.84 years was predicted. Compared to the reliability prediction method, this method doesn’t rely on the failure rate in the handbook and has high precision. Compared to the accelerated life test method, this method has lower cost and test time, which has a bright application prospect.
Vzhľadom na neustále sa meniace požiadavky účastníkov cestnej premávky je potrebné vytvoriť dopravnú infraštruktúru, ktorá bude schopná plniť tieto požiadavky a zaviesť také organizačné opatrenia aby sa dosiahlo jej efektívne využitie. V našom príspevku sme sa zamerali na simuláciu dopravnej situácie na cestnej sieti medzi mestami Bytča a Ružomberok, kde sa často vyskytujú dopravné nehody a kongescie. Daný úsek patrí medzi najviac vyťažené úseky cestnej siete v Slovenskej republike.
Railroad engineering and operation, Industrial engineering. Management engineering
Taking CX1015/08 LB electromagnetic contactor utilized in CRH3 EMUs as study object, a new method for judging contactoroperating mechanism failure by checking and comparing the coil current curves was proposed, which could quantify the failure status byanalyzing coil current waveform. Probability of the method was confirmed by test results, a test system design scheme was provided for realtimemonitoring the working status of the electromagnetic contactor.