High-speed Operation Research Articles

Experimental determination of lateral sway of a pneumatic spring when passing through a railroad switch in conditions of provision of high-speed trains` safety

Experimental determination of lateral sway of a pneumatic spring when passing through a railroad switch in conditions of provision of high-speed trains` safety

Enhanced perpendicular magnetic anisotropy energy and Curie temperature in the CrOCl monolayer: strain effects

Abstract Magnetic monolayers offer a wide variety of applications in enhancing the functionalities of storage devices including higher thermal stability, lower power consumption, and higher operation speed, owing to their intrinsic long-range spin ordering. Herein, we study the biaxial ([110]) strain range of ± 5% influence on the formation energetics, electronic structure, and magnetic behaviour of the CrOCl monolayer (ML) based on the ab-initio calculations including spin–orbit coupling (SOC) effects. It is predicted that the system displays an insulating character having an energy band gap (E g ) of 2.05 eV with a ferromagnetic (FM) ground state in its unstrained state. The estimated partial spin magnetic moment on the Cr ion is +2.7 μ B /f.u. (per formula unit) with S = 1.5 and lies in a + 3 oxidation state with an electronic distribution of t 2 g 3 ↑ t 2 g 0 ↓ e g 0 ↑ e g 0 ↓ . Along with this, [001] (c-axis) is found to be the easy magnetic axis, which results in a magnetic anisotropy energy (MAE) of 0.2 meV having an MAE constant of 0.25 mJ m−2 and the computed Curie temperature (T c ) using Ising model is 157 K. Furthermore, the system shows the robustness of the FM insulating behavior against considered strains. However, a significant shift in the conduction band edge (CBE) position to lower energies is evident for tensile strains, which substantially reduces the E g up to 13%. The decrease in E g value is evidence of higher absorption in the visible range which makes it the best option for optoelectronics and photocatalysis. Simultaneously, our results revealed that strain enhances the MAE and T c up to 190% and 43%, respectively. Hence, optimized E g , MAE, and T c within a considerable strain range, make the CrOCl ML a potential candidate for its utilization in magnetic memory devices.

Refinement of Control Strategies for Wheel-Fan Systems in High-Speed Air-Floating Vehicles Operating in Atmospheric Pressure Pipelines

This study explored the optimization of control systems for atmospheric pipeline air-floating vehicles traveling at ground level by introducing a novel composite wheel-fan system that integrates both wheels and fans. To evaluate the control impedance, the system simulates road conditions like inclines, uneven surfaces, and obstacles by using fixed, random, and high torque settings. The hub motor of the wheel fan is managed through three distinct algorithms: PID, fuzzy PID, and the backpropagation neural network (BP). Each algorithm’s control strategy is outlined, and tracking experiments were conducted across straight, circular, and curved trajectories. Analysis of these experiments supports a hybrid control approach: initiating with fuzzy PID, employing the PID algorithm on straight paths, and utilizing the BP neural network for sinusoidal and circular paths. The adaptive capacity of the BP neural network suggests its potential to eventually supplant the PID algorithm in straight path scenarios over extended testing and operation, ensuring improved control performance.

LCRTR-Net: A low-cost real-time recognition network for rail corrugation in railway transportation

Rail corrugation has a significant impact on the safety of high-speed railway operations, making its identification particularly important. Traditional manual inspection methods are infeasible for large-scale identification within limited time frames, while existing methods based on machine vision or axle box acceleration face challenges such as high costs, complex equipment installation and maintenance, as well as difficulties in achieving real-time performance. To address these challenges, this study proposes an innovative low-cost real-time recognition network (LCRTR-Net), which utilizes accelerometers installed on the underside of the train body and combines wavelet packet decomposition with dilated causal convolution in a residual neural network. Specifically, the approach first extracts the latent features of train body acceleration caused by rail corrugation through wavelet packet decomposition and reconstruction. Next, dilated causal convolution is employed to capture the temporal causal relationships and long-term dependencies of these latent features. Finally, the integration of residual connections further enhances the feature extraction performance and computational efficiency of LCRTR-Net. Experimental results demonstrate that LCRTR-Net exhibits significant generalization ability and real-time performance, achieving an average recognition accuracy exceeding 97.0%, with a recognition time of only 0.17 ms per rail corrugation sample, significantly outperforming existing rail corrugation recognition methods. This indicates that LCRTR-Net has broad application potential in practical railway operations. Future research directions will focus on unsupervised or few-shot learning algorithms and multi-sensor integration to further improve recognition accuracy and real-time performance, promoting the practical application of this technology.

Vehicle Target Detection Using the Improved YOLOv5s Algorithm

This paper explores the application of the YOLOv5s algorithm integrated with the DeepSORT tracking detection algorithm in vehicle target detection, leveraging its advantages in data processing, loss function, network structure, and training strategy. Regarding detection frame regression, adopting Focal-EIOU can improve vehicle detection accuracy by precisely measuring overlap and better handle complex scenarios, enhancing the overall performance. The CoordConv convolution layer with more spatial position information is employed to enhance the original network structure’s convolution layer and improve vehicle positioning accuracy. The principle and effectiveness of the Shuffle Attention mechanism are analyzed and added to the YOLOv5s network structure to enhance training, improve detection accuracy and running speed. And the DeepSORT tracking detection algorithm is designed to achieve high-speed operation and high-accuracy matching in target tracking, enabling efficient and reliable tracking of objects. Simultaneously, the network structure is optimized to enhance algorithmic speed and performance. To meet the requirements of vehicle detection in practical transportation systems, real-world vehicle images are collected as a dataset for model training to achieve accurate vehicle detection. The results show that the accuracy rate P of the improved YOLOv5s algorithm is increased by 0.484%, and mAP_0.5:0.95 reaches 92.221%, with an increase of 1.747%.

Research on control sequence of work mode switching for planetary row multi-mode hybrid powertrain system

According to the characteristics of the planetary row hybrid power system, it is an important issue for the system to adopt a reasonable working mode to realize the efficient operation of the hybrid power system in different operating conditions. Paper takes the single-row hybrid system as the research object. To address the complexity of the working model, a self-construction method using vehicle modeling is proposed. State-space equations are developed for each mode, and an objective function model integrating main and sub-mode switching rules is constructed using the DP algorithm. Learning Vector Quantization (LVQ) network clustering extracts mode-switching sequences. Urban and highway cycles (UDDS and HWFET) are chosen as global optimization parameters. The DP algorithm’s global optimization is applied, extracting sequence basis from UDDS and HWFET compound conditions. Utilizing LVQ input data, the main mode’s power demand is divided into 4 sub-mode regions, generating a switching sequence diagram. Joint simulations verify the effectiveness. ECMS control with regular mode switching yields 4.7458 L/100 km fuel consumption under UDDS & HWFET, 5.53% higher than DP optimization. WLTC conditions, with more medium and high-speed operation, consumption is 5.031 L/100 km, offering further optimization potential.

Operational Adaptability Improvement of High-Speed Trains Through Multi-Objective Control on Carbody Lateral Vibration

To improve the operational adaptability of high-speed trains, a control method is proposed to mitigate carbody lateral vibration by leveraging the dynamic vibration absorption effect of multi-suspended equipment. A comprehensive analysis of five typical wheel/rail contact relationships, closely related to vehicle operational status in the long-term service, is conducted and incorporated into the established rigid-flexible coupling dynamic model. Based on the proposed improved niche genetic algorithm (INGA), an objective function, which holistically assesses the vibration of the carbody and suspended equipment, is constructed to undertake the optimization analysis. The results show that the dynamic vibration absorption effect of the suspended equipment proves effective in controlling carbody lateral vibration, thereby enhancing operational adaptability. However, the improvement in vehicle performance varies under different operating conditions, influenced by the competitive relationship between multiple control objectives. While carbody lateral vibration performance could be further improved without considering equipment vibration tolerance, such improvements are limited, indicating that it is reasonable and necessary to consider equipment vibration tolerance in the research of carbody vibration control. This study furnishes valuable insights for improving the adaptability of high-speed train operations and provides ideas for further research on carbody vibration control using the suspended equipment.

Ta alloy doped InSbTe ensuring high thermal stability and fast operation speed in phase change memory

The excellent performance of phase change memory (PCM) in non-volatile and storage density makes it one of the most attractive solutions for storage-class memory and neuromorphic computing, whereas the slow operation and low thermal stability limit its extensive applications. Here Ta-doped In0.43Sb2Te3has been proposed, which enhances the amorphous stability without sacrificing its operating speed. Ta0.12(In0.43Sb2Te3)0.88 film possess excellent 10-year data retention temperature of 184.5 °C and the PCM based on Ta0.12(In0.43Sb2Te3)0.88 achieved an operating speed of 6 ns. Both experimental results indicate that Ta doping reduces grain size, enhances the ability to maintain face-center cubic phase, and improves phase separation caused by In doping. A long endurance of 1 × 106 has been achieved, which is originating from the small volume change of 1.71 %. Therefore, Ta0.12(In0.43Sb2Te3)0.88 material is a potential candidate for application in PCM.

Thermal-Gas-Elastic Coupling Modeling and Performance Analysis of Foil Cylindrical gas Film Seal Considering Speed Slip, Temperature Jump and Shaft Misalignment

Abstract The Compliant foil cylindrical gas film seal is an advanced sealing technology designed for high-speed and high-temperature conditions in a jet engine. Its design involves using a compliant foil to create a cylindrical sealing surface, achieving adaptive sealing in environments with high pressure differences and rotational speeds. For high-speed and high-temperature operation, a speed slip flow model was established by considering film slip flow, wall temperature jump, foil deformation, and gas viscosity-temperature thermal effects. The variations in the lubrication performance of the foil cylindrical gas film seal with changes in shaft misalignment directions, misalignment angles, and operating parameters were investigated. The speed slip leads to a decrease in gas film lift and an increase in leakage. The wall temperature jump phenomenon caused by speed slip leads to a 2.56% decrease in film temperature. The shaft misalignment angles on the high-pressure and low-pressure sides have different impacts on the flow field, with film pressure and temperature differing by 66.78% and 11.19%, respectively.

Picosecond Operation of Optoelectronic Hybrid Phase Change Memory Based on Si‐Doped Sb Films

AbstractPhase‐change random access memory is anticipated to break the bottleneck of the “storage wall” due to its advantages in simultaneous data storage and in‐memory computing. However, operation speed constrains its application scenarios. Antimony (Sb) thin film has ultrafast phase change speeds, low power consumption, and a straightforward chemical composition. In this study, silicon (Si) doping is employed to enhance the stability of pure Sb while achieving both ultrafast operational speeds and superior thermal stability concurrently. By utilizing optoelectronic hybrid phase change memory, the SET and RESET operation speeds can reach as fast as 26 and 13 ps, respectively, when using Si‐doped Sb films. The absence of the Si─Sb bond results in simple cubic nuclei within the amorphous film, which is posited as the structural basis for the high operational speed. These novel insights into ultrafast speed and phase mechanisms are poised to have valuable evidence for future high‐speed memory designs.

Research on digital twin technology and its application in intelligent operation and maintenance of high-speed railway infrastructure

PurposeThis paper analyzes the application of digital twin technology in the field of intelligent operation and maintenance of high-speed railway infrastructure from the perspective of top-level design.Design/methodology/approachThis paper provides a comprehensive overview of the definition, connotations, characteristics and key technologies of digital twin technology. It also conducts a thorough analysis of the current state of digital twin applications, with a particular focus on the overall requirements for intelligent operation and maintenance of high-speed railway infrastructure. Using the Jinan Yellow River Bridge on the Beijing–Shanghai high-speed railway as a case study, the paper details the construction process of the twin system from the perspectives of system architecture, theoretical definition, model construction and platform design.FindingsDigital twin technology can play an important role in the whole life cycle management, fault prediction and condition monitoring in the field of high-speed rail operation and maintenance. Digital twin technology is of great significance to improve the intelligent level of high-speed railway operation and management.Originality/valueThis paper systematically summarizes the main components of digital twin railway. The general framework of the digital twin bridge is given, and its application in the field of intelligent operation and maintenance is prospected.

Harnessing the Distributed Computing Paradigm for Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy allows fast and versatile elemental analysis, standing as a promising technique for a wide range of applications both at the research and industry levels. Yet, its high operation speed comes with a high throughput of data, which introduces some challenges at the level of the data processing domain, mainly due to the large computational load and data volume. In this work, we analyze and discuss opportunities of distributed computing paradigms and resources to address some of these challenges, covering most of the procedures usually employed in typical applications. We infer the possible impact of such computing resources by presenting some metrics of simple processing prototypes running in state-of-the-art computing facilities. Our results allow us to conclude that, while underexplored so far, these computing resources may allow for the development of tools for timely research and analysis in demanding applications and introduce novel solutions toward a more agile working environment.

A decomposition approach to solve the individual railway crew Re-planning problem

Crew re-planning is an important and difficult task in railway crew management. In this paper, we establish a path-based model solving the Individual Crew Re-planning Problem (ICRP). The individual indicates that we focus the problem on specific (non-anonymous) crew members, considering their roles (leader and cabin crew) and qualifications. This problem is inspired by the crew planning problem faced in Chinese high-speed railway operations. To generate feasible paths, we construct a multi-layer time-space connection network and develop a heuristic algorithm. To decrease the complexity and scale of the model, we decompose the ICRP into two sub-problems (for leaders and for cabin crew members respectively) which can be solved in sequence. In addition, we develop a Lagrangian relaxation (LR) algorithm to get valid paths quickly for both sub-problems. We combine the LR algorithm with solving the restricted decomposed models to get a good quality solution for the studied ICRP problem. We test our methods on several real-world instances from Chinese high-speed railways. The computational experiments show that our LR algorithm with a decomposition strategy can solve the decomposed models in a relatively short computation time compared to solving the original model directly, while obtaining (near-)optimal solutions for all instances.

Development of a cell-type cylindrical carrot seeder

Accurate planting of the required number of carrot seeds is one of the important parameters in developing a carrot seeding device. This study developed a metering mechanism that promotes the deposition of <3 carrot seeds on each planting hill at negligible seed damage. The metering disc and hopper were especifically designed to ensure consistency and uniformity in seed loading into the seed cell and their subsequent efficient discharge onto the planting hills. A key feature of the design is the clearance between the metering disc and the hopper, which was strategically designed to scrape excess seeds from the seed cells, allowing the surplus to freely slide back into the hopper without causing damage. The performance of the seeder was evaluated by examining key parameters, including the number of seeds dropped per hill, scattering index, hill diameter, hill spacing, and missing index across various operating speeds (60, 80, 100, 120, and 140 cm/s). The results demonstrated that the seeder achieved optimal performance at operating speeds between 80–120 cm/s, with an average of 1.70 to 1.81 seeds dropped per hill. Mean hill spacing between hills ranged from 10.98 to 13.50 cm at speeds below 120 cm/s. At a higher speed of 140 cm/s, the mean hill spacing and missing index were 23.06 cm and 53.33 %, respectively. Additionally, the scattering index decreased at a higher operating speed. The developed metering mechanism significantly enhanced the efficiency of the seeder, ensuring precise seed placement and reducing seed wastage across varying operating conditions.

Discrete Element Analysis of the Dynamic Mechanical Characteristics of Ballasted Track on Bridges Under Train Loading

The operation and service performance of ballasted track on bridges face significant challenges due to high-speed railway train operations. To investigate the mechanical characteristics of ballasted track on bridges, field experiments were conducted. A coupling model of ballasted track on a simply-supported girder bridge was established using the coupling method of discrete element and multi-flexible body dynamics and analyzes the changes in ballast bed settlement deformation, stiffness and energy with increasing load cycles. The findings reveal that dynamic loading alters the original contact state of ballast particles, displaying notable anisotropy vertically and longitudinally and isotropy horizontally. The vibration of ballast particles on bridges is more pronounced than on the subgrade, with vibration acceleration under the sleeper at 150[Formula: see text]mm depth on the bridge being 2.89 times that on the subgrade foundation. As the system stabilizes, the interlocking effect among granular ballast particles strengthens, reducing mutual sliding and increasing ballast bed stiffness by approximately 7.8–9.5% compared to the initial state, while total energy and dissipated energy gradually decrease. It is recommended to monitor the quality of ballast particles under the sleeper of ballasted tracks on bridges, implement vibration mitigation measures, or periodically replace ballast particles.

Time-encoded photonic quantum states: Generation, processing, and applications

Encoding and processing quantum information in the time-of-arrival of photons offer significant advantages for quantum information science and technology. These advantages include ease of experimental realization, robustness over photon state transmission, and compatibility with existing telecommunication infrastructure. Additionally, time-of-arrival encoding has the potential for high-rate quantum communication and holds promise for the future development of quantum internet. This review explores the generation, processing, and applications of time-encoded quantum states, focusing on both single-photon states, energy–time entanglement, and time-bin entanglement. We summarize the nonlinear optics platforms and advanced laser and modulation techniques utilized for photon sources that enable quantum information encoding onto the photons' time-of-arrival. We also highlight advanced quantum state processing methods in the time domain, including the Franson interferometry, optical switch-based schemes, and state-of-the-art measurement and detection schemes that allow for high-speed and multi-dimensional quantum operations. Finally, we review the mainstream implementations mainly including the quantum communication demonstrations and outline future directions for developing practical quantum networks leveraging time-encoded photon states.

Enabling Fast Photoresponse in Hybrid Perovskite/MoS2 Photodetectors by Separating Local Photocharge Generation and Recombination.

Interfacing CH3NH3PbI3 (MAPbI3) with 2D van der Waals materials in lateral photodetectors can suppress the dark current and driving voltage, while the interlayer charge separation also renders slower charge dynamics. In this work, we show that more than one order of magnitude faster photoresponse time can be achieved in MAPbI3/MoS2 lateral photodetectors by locally separating the photocharge generation and recombination through a parallel channel of single-layer MAPbI3. Photocurrent (Iph) mapping reveals electron diffusion lengths of about 20 μm in single-layer MAPbI3 and 4 μm in the MAPbI3/MoS2 heterostructure. The illumination-power scaling of Iph and time-resolved photoluminescence studies point to the dominant roles of the heterostructure region in photogeneration and single-layer MAPbI3 in charge recombination. Our results shed new light on the material design that can concurrently enhance photoresponsivity, reduce driving voltage, and sustain high operation speed, paving the path for developing high-performance lateral photodetectors based on hybrid perovskites.

Effect of Induced Wheel and Impeller Inlet Diameter on the Hydrodynamic Performance of High-speed Centrifugal Pumps

The high-speed centrifugal pump plays a crucial role in fields such as aerospace and petrochemical industries, owing to its characteristics of elevated rotational speed and high head. During high-speed operation, the centrifugal pump is prone to cavitation, which alters the fluid flow state within the pump, leading to vibrations, noise, and a sudden decrease in pump head and efficiency. Simultaneously, the collapse of cavitation bubbles generates impact pressure that can damage the pump's internal flow components, significantly reducing its operational lifespan and causing severe consequences. Moreover, under constant-flow conditions, the absolute and relative velocities of the fluid at the impeller inlet are functions of the suction pipe diameter. Therefore, there exists an optimal value for the impeller inlet diameter to enhance the centrifugal pump's resistance to cavitation. Similarly, the different geometric and structural parameters of the inducer also influence the hydraulic performance of the centrifugal pump. The focus of this study is on the external characteristics and internal flow patterns of an optimized high-speed centrifugal pump. In this paper, the entire flow field of the model pump is numerically simulated using ANSYS CFX software. The performance and overall flow field state of the high-speed centrifugal pump under different impeller configurations and inlet diameters are explored. The influence of blade wrap angle and inlet diameter on the high-speed centrifugal pump is revealed, providing a theoretical basis for subsequent optimal design.

Practice and validation of inversion of seismic source localisation based on genetic algorithm

As the mining depth of coal resources increases, resulting in frequent mine earthquakes during mining. In this study, the rolling window ratio method is firstly chosen as the seismic phase recognition method to read the mine earthquake data received by the microseismic sensor. Secondly, the improved genetic algorithm is used as the optimization algorithm of the objective function to build the algorithmic framework of accurate inverse localization of mine earthquake. Finally, the accuracy of the algorithm for seismic source localization is verified based on actual engineering cases. Results show that the first arrival time extraction by the rolling window ratio method has the advantages of high accuracy and fast algorithm operation speed. The Fast Fourier Transform-Butterworth joint noise reduction method has a good noise reduction effect, which successfully suppresses the noise outside the mine earthquake signal and effectively improves the problem of much noise in the mine earthquake signal. Compared with the microseismic monitoring date, the mine earthquake localization error is within 5%.

Static Approximate Modified Mirror—Full Adder for High Speed and Low Power Operations Using 32 nm CNTFET Technology

ABSTRACTThe error tolerance nature of the digital multimedia applications enables the implementation of approximate digital circuits to achieve the benefits of high speed of operation and low power consumption. This paper proposes a static approximate modified mirror full adder (SAMM‐FA) circuit designed using logic level approximation to reduce the number of transistors in the circuit. Owing to the balanced electrical characteristics, better stability and higher on‐current to off‐current ratio (Ion/Ioff), 32 nm carbon nanotube field effect transistor (CNTFET) technology has been used for implementing the proposed circuit in the Cadence Virtuoso tool. Featuring only 10 transistors and operating at a supply voltage of 0.5 V, the proposed SAMM‐FA has a low power dissipation of just 4.14 nW, and propagation delay of just 3.82 ps. The power delay product and energy delay product figure of merits of the proposed circuit are found to be excellent when compared with the contemporary designs.