High-speed System Research Articles

Exploration of the effect of fractional elements in nonlinear transmission lines

Purpose The purpose of this paper is to explore how fractional derivatives affect the transient and steady-state behaviour of nonlinear transmission lines. This problem is of significance for high-frequency design of systems such as high-speed sampling systems and radar systems. Design/methodology/approach This paper shall consider the transient and steady-state responses of nonlinear transmission lines when fractional derivatives are considered. A lumped-parameter model is considered and the product-integration implicit trapezoidal rule shall be used for simulations. Findings The important observation is that small deviations of the order of the derivative from an integer order can have a significant effect on the transient and steady-state behaviour. This includes a change in the speed of the wave on the transmission line and on its damping. Originality/value The work is novel as it uses a lumped-parameter model with nonlinear capacitors and explores the effect on the dynamical behaviour when fractional derivatives are present. This is in contrast to the typical approach of using a partial differential equation derived under certain assumptions such as the nature of the nonlinear capacitor.

A newly developed multi-kilo-channel high-speed and high-precision waveform digitization system for Jinping Neutrino Experiment

A newly developed multi-kilo-channel high-speed and high-precision waveform digitization system for Jinping Neutrino Experiment

Wind speed forecasting in high-speed railway system based on secondary decomposition and gated recurrent unit network

Wind speed forecasting in high-speed railway system based on secondary decomposition and gated recurrent unit network

Three-dimensional characterization of nanoporous membranes by capillary filling using high speed interferometry.

A high-speed interferometric system was developed to analyze nanostructured porous silicon (PS) membranes by measuring reflectance variations during capillary filling from both sides. A high-speed camera was employed to capture the reflectance evolution of the entire sample area with the necessary temporal resolution, providing quantitative information on filling dynamics. By integrating these data with a simple fluid dynamic model, it is possible to examine the internal structure of the membranes and determine the effective pore radii profiles along their thickness. The system is capable of accurately measuring radii within the range of 10-20nm, with a spatial resolution of ∼20 μm and an in-depth resolution of ≈1μm. This three-dimensional characterization provides valuable insights into the complex morphology of PS membranes and can be applied to other nanostructured porous materials.

Dynamic analysis of high-speed vehicle-track coupled system due to lateral differential deformation induced by subgrade frost heave

Dynamic analysis of high-speed vehicle-track coupled system due to lateral differential deformation induced by subgrade frost heave

Identification of structured features for positioning in the guideway maintenance of high-speed maglev system

Identification of structured features for positioning in the guideway maintenance of high-speed maglev system

Modeling and validation of high-speed pneumatic system for interstage separation

Modeling and validation of high-speed pneumatic system for interstage separation

Study on failure analysis and reliability optimization of high-speed railway fastener system

Study on failure analysis and reliability optimization of high-speed railway fastener system

Twin spacing manipulation of (111)-orientation nanotwinned copper via the aeration flow control in the high-speed direct-current electroplating system with thiol organic additives

It is a challenge to develop a cost-effective and time-efficient process for manufacturing nanotwinned copper foils with the precise control of twin spacing, a crucial determinant of the nanotwinned copper...

Problems and Solutions in US Stock Market

This research explores critical challenges facing the U.S. stock market, specifically focusing on the impacts of algorithmic trading-induced market volatility and cybersecurity threats. Algorithmic trading, which utilizes high-speed computer systems to make trades, has increased market efficiency but also introduced risks of extreme price fluctuations and flash crashes. In parallel, the digitalization of financial markets has heightened exposure to cybersecurity threats, posing risks to trading integrity and data security. To address these issues, this study proposes two targeted solutions. For the issue of market volatility driven by algorithmic trading, the research recommends implementing circuit breakers and trading halts. These mechanisms can prevent severe market disruptions by temporarily pausing trading during extreme price movements, allowing the market to stabilize and preventing panic-driven selloffs. For the cybersecurity challenges, the study suggests enhancing information sharing and fostering collaborative defense strategies among financial institutions and regulatory bodies. By encouraging greater collaboration, the financial sector can more effectively identify and counteract cybersecurity threats, reducing vulnerabilities across the market.

Horizontal vibration and control methods in high-speed elevator car systems: a review

Horizontal vibration and control methods in high-speed elevator car systems: a review

Research on explicit model predictive control method for horizontal vibration of high-speed elevator car system

Research on explicit model predictive control method for horizontal vibration of high-speed elevator car system

Design and Development of a Precision Defect Detection System Based on a Line Scan Camera Using Deep Learning

The manufacturing industry environment is rapidly evolving into smart manufacturing. It prioritizes digital innovations such as AI and digital transformation (DX) to increase productivity and create value through automation and intelligence. Vision systems for defect detection and quality control are being implemented across industries, including electronics, semiconductors, printing, metal, food, and packaging. Small and medium-sized manufacturing companies are increasingly demanding smart factory solutions for quality control to create added value and enhance competitiveness. In this paper, we design and develop a high-speed defect detection system based on a line-scan camera using deep learning. The camera is positioned for side-view imaging, allowing for detailed inspection of the component mounting and soldering quality on PCBs. To detect defects on PCBs, the system gathers extensive images of both flawless and defective products to train a deep learning model. An AI engine generated through this deep learning process is then applied to conduct defect inspections. The developed high-speed defect detection system was evaluated to have an accuracy of 99.5% in the experiment. This will be highly beneficial for precision quality management in small- and medium-sized enterprises

WS2/Graphene/MoS2 Sandwich van der Waals Heterojunction for Fast-Response Photodetectors.

Fast-response photodetectors have attracted considerable attention in the application of high-speed communication, real-time monitoring, and optical imaging systems. However, most reported photodetectors suffer from limitations of the inherent properties of materials, low carrier transport efficiency, and unmatched interfaces, which lead to a low response speed. Here, we report a WS2/graphene/MoS2 vertical van der Waals heterojunction fabricated by mechanical exfoliation and dry transfer methods for fast response. To improve the response speed of the previously reported WS2/MoS2 heterojunction with excellent photoelectric performances, the embedded graphene is employed to optimize the interface defects and improve the carrier transport efficiency due to its high mobility and smooth and flat surface. Under the illuminations of a 405 nm laser and a bias voltage of 0.5 V, our device can realize rise and fall times of 44 and 52 μs, respectively. For a bias voltage of 2.5 V, moreover, the device can also show outstanding performances including a high responsivity of 220 A/W, a considerable detectivity of 1.2 × 1013 Jones, a large external quantum efficiency of 6.7 × 104 %, and a low dark current of 1.05 × 10-13 A. Additionally, the device enables high-speed transmission with a low bit error rate in a closed-loop optical communication system. Therefore, the proposed scheme can provide an idea for the design of photodetectors with fast response and high performance.

A high-speed camera-based measurement system for monitoring and controlling the induced jet break-up fabrication of advanced ceramic breeder pebbles

The production of lithium-rich ceramic pebbles is crucial for future fusion reactors, as they are one of the most important components of the tritium-breeding blankets. In order to produce high-quality pebbles, a melt-based fabrication process KALOS (KArlsruhe Lithium OrthoSilicate) has been developed at the Karlsruhe Institute of Technology (KIT), which produces pebbles utilising the break-up of a molten laminar jet. Since the production of the pebbles is very precise (with diameters of hundreds of micrometres) and significantly influenced by process parameters, a system that monitors and regulates the fabrication in real-time is essential. This paper elaborates on a high-speed camera-based measurement system for automatically monitoring and controlling the production process. Experimental proof demonstrates that the presented measurement system can provide the real-time sizes, locations and distance distribution of the molten ceramic droplets accurately. In addition, the system is also designed to enable the control of the pebble production by adjusting a production parameter, i.e. the driving frequency, based on the real-time output of the proposed measurement system.

FPGA Implementation for 24.576-Gbit/s Optical PAM4 Signal Transmission with MLP-Based Digital Pre-Distortion.

In this work, we implemented a short-reach real-time optical communication system using MLP for pre-distortion. Lookup table (LUT) algorithms are commonly employed for pre-distortion in intensity modulation and direct detection (IM/DD) systems. However, storage limitations typically restrict the LUT pattern length to 9, limiting its effectiveness in compensating for nonlinear effects. A multilayer perceptron (MLP) can overcome this limitation by predicting errors and generating pre-distorted signals, thus replacing the extensive storage requirements of LUTs with minimal computational resources. The MLP-based digital pre-distortion (MLP-DPD) technique enables the creation of long-pattern LUTs for improved nonlinear compensation. In this work, an MLP-DPD scheme was implemented on a field-programmable gate array (FPGA). The FPGA was used to generate a 14.7456 GBaud pre-distorted pulse amplitude modulation 4-level (PAM4) signal. This signal was then transmitted over 20 km of standard single-mode fiber (SSMF). At the receiver, the parallel constant modulus algorithm (PCMA) was applied for signal processing. The bit error rate (BER) achieved met the 2.4 × 10-2 threshold for soft-decision forward error correction (SD-FEC), enabling a net transmission bit rate of 24.576 Gbit/s. This approach demonstrates the feasibility of using MLP-DPD for effective nonlinear compensation in high-speed optical communication systems with limited resources.

Exact analytic technique for designing controller architecture in multi-axis active magnetic bearings with rotor eccentricities

Multi-coil active magnetic bearing systems require an efficient controller design to maintain stability, maximize performance, and improve flexibility in high-speed transport systems, particularly those used in electric cars, military, and aerospace. By employing Fourier-based frameworks rather than conventional Laplace-based methods, the work reported here simplifies the AMBs controllers, offering more flexibility to complex dynamics and adaptability to non-linearity. For computational and mathematical brevity, the entire formulation has been linearized around a specific range of uncertainty in this work. The magnetic field pattern with rotor eccentricities is characterized by using a subdomain technique and a perturbation methodology. Complex magnetic field formulations are obtained by the estimation of zeroth and first-order formulae in polar coordinates. For every coil, predictive model-based interpolation functions are constructed and optimal controller settings for stability are found by eigenvalue evaluation. The study enhances accuracy and effectiveness by validating these analytical methods against numerical results, offering deeper insights into rotor dynamics and controller adjustments.

Study on applicability of rocking piers to high-speed railway bridge-track system under strong ground motions

Rocking piers have significant advantages in limiting the residual post-earthquake displacement of the pier top and reducing thus the structural damage. However, the application and research of such kind of piers are mainly concentrated on highway bridges. To study the applicability of rocking pier in high-speed railway (HSR) bridge-track system under strong ground motions, a preliminary rocking seismic design method for HSR gravity piers is proposed. The HSR simply supported beam bridge-track-subgrade integrated finite element model of the conventional pier system and the rocking pier system are established. The seismic response of the two pier systems under strong ground motions is compared and analysed. Results show that under strong ground motions, in the HSR bridge-track system, rocking bridge piers can exhibit smaller bending moments at the pier bottom and residual displacement at the pier top concerning conventional piers. Hence, the piers can effectively be protected from damage during a seismic event, while the bearings and the sliding layer exhibit smaller residual post-earthquake deformation. Thereby, with this system, it is possible to significantly improve the geometric irregularities of the rails, and increase the safety and comfort of running after strong ground motions.

Research on Velocity Test of Fragment Group of Gradient Scattering Preformed Fragment Warhead

Abstract In order to obtain the velocity of the fragment group of gradient scattering preformed fragment warhead, the radial scattering field of the fragments was photographed by the laser high-speed CCD camera system, and the velocities of all the fragments in the image after filtering the explosion firelight were obtained. The velocity of the preformed fragments shows a continuous gradient distribution from 77.9 m/s to 424.2 m/s, which was consistent with the theoretical calculation results. This indicates that the test technology is feasible and provides a new method for the velocity test of the fragment group.

Femtosecond laser direct writing of fiber bragg grating with high-speed and high-resolution scanning technique

We employed two fabrication methods, a laser scanning system and a phase mask, to produce Fiber Bragg Gratings (FBGs). A micro-scanning adapter was used to enable high-speed and high-resolution laser focusing inside the optical fiber via a scanner and an objective lens. By continuously moving the fiber-fixed stage while adjusting the scanner repetition speed, micropatterns with various periods were generated. This approach allowed for the detection of FBG signals at multiple wavelengths.Laser direct writing, utilizing a high-speed and high-resolution laser scanning system, facilitated FBG production without the need to remove the fiber coating. This method provided a straightforward way to control the FBG wavelength, signal intensity, and bandwidth by adjusting the scanner and stage movement speeds. The use of femtosecond lasers for FBG fabrication offers the additional advantage of reduced material dependence, enabling FBG production in various optical fibers without requiring additional processing steps compared to conventional methods.