transform Huang − Railway track inspection based on the vibration response to a scheduled train and the Hilbert Abstract With the development of high-density intercity railway networks, substantial investments are now required, in terms of labor and machinery, in order to be able to conduct safety inspections. This results in high operational costs. Highcapacity and high-speed operations have resulted in levels of damage and deterioration of railway system components that have surpassed all expected values. Thus, traditional methods of periodic inspection, though still necessary, are no longer sufficient to detect the rapid development of defects on railway systems. Therefore, the direct use of operational trains as inspection vehicles to detect defects in real-time has become a current trend in the development of inspection techniques. This study applies an inspection technique previously reported in the literature to on-site testing of track. The response to vibrations on railway bridges, track system components and track irregularities are also studied. The effects are analyzed using the Hilbert-Huang transform approach. It is shown that the proposed data analysis method can be used in conjunction with the routine operation of trains to create a method for the monitoring of track defects.

The flyback converters are widely used in low power applications. The switch typically requires 600 V breakdown voltage in order to perform large step-down voltage. Thus, slight variation on the switch control can either permanently damage the switch or decrease the efficiency of the power conversion. In order to achieve higher power efficiency, the previous literature suggested operating the flyback converter in the discontinuous current mode (DCM). It is then required to understand the critical conditions of the DCM through analyzing the dynamic behavior and discontinuous current mechanism. This paper started from the current waveform analyses, proceeded to the derivation of zero current switching (ZCS) formulation, and finally reached the necessary conditions for the DCM. The entire DCM operation was divided into three phases that subsequently affect the result of the zero voltage switching (ZVS) and then to the ZCS. The experiment shows a power efficiency of over 96% when the output power is around 65 W. The switch used in this paper is a Gallium Nitride High-Electron-Mobility Transistor (GaN HEMT) that is advantageous at the high breakdown voltage up to 800 V. The important findings from the experiments include that the output power increases with the increasing input DC voltage and the duty cycle is rather linearly decreasing with the increasing switching frequency when both the zero voltage switching (ZVS) and ZCS conditions are satisfied simultaneously.

Advances in conventional industrial controllers have led to new technologies such as multilanguage use, cross-platform applications, and remote monitoring and control. However, the human-machine interfaces (HMIs) of conventional industrial controllers and mobile devices cannot directly transmit instant messages to each other. This study describes a simple method of upgrading the HMIs of conventional industrial controllers into controllers capable of Web-based remote access. The study began with the development of a model-view-controller architecture consisting of Hypertext Markup Language, Cascading Style Sheets, and JavaScript and proceeded to the implementation of a single-page application (SPA) method through AJAX and WebSocket, which communicates with the back-end Node.js server to transfer data. Future advancements will enable information to flow through cross-platform devices across various operating systems and Web browsers, allowing users to remotely monitor and control machines from mobile smart devices. We demonstrated the simplicity of the SPA method by transforming a conventional personal computer-based industrial controller, WINPC32, to an all-purpose Web-based HMI for industrial use with the graphic user interface software, GPX.

In this paper, we develop a variable-frequency pulse width modulation (VFPWM) circuit for input control of 6.78-MHz resonant wireless power transfer (WPT) systems. The zero-voltage switching control relies on the adjustments of both duty cycle and switching frequency for the class-E amplifier used in the WPT as the power transmission unit. High-frequency pulse wave modulation integrated circuits exist, but some have insufficiently high frequency or unfavorable resolution for duty cycle tuning. The novelty of this work is the VFPWM circuit design that we put together. A voltage-controlled oscillator (VCO) of radio frequency and capacitor-coupled difference amplifiers are used to simultaneously perform the frequency and duty cycle tuning required in resonant WPT applications. Different circuit topologies of VFPWM are compared analytically and numerically. The most favorable circuit topology, enabling independent control of the frequency and duty cycle, is employed in experiments. The experimental results demonstrate the validity of the novel VFPWM, which is capable of operating at 6.78 MHz and has a duty ratio adjustable from 20% to 45% of the range applicable in the resonant WPT applications.

This paper attempts to disclose a new GaN-based device, called the P-Cascode GaN HEMT, which uses only a single gate driver to control both the D-mode GaN and PMOS transistors. The merit of this synchronous buck converter is that it can reduce the circuit complexity of the synchronous buck converter, which is widely used to provide non-isolated power for low-voltage and high-current supply to system chips; therefore, the power conversion efficiency of the converter can be improved. In addition, the high side switch using a single D-mode GaN HEMT, which has no body diode, can prevent the bi-directional flow and thus reduce the power loss and cost compared to a design based on a series of two opposite MOSFETs. The experiment shows that the proposed P-Cascode GaN HEMT efficiency is above 98% when it operates at 500 kHz with 6 W output. With the input voltage at 12 V, the synchronous buck converter provides an adjustable regulated output voltage from 1.2 V to 10 V while delivering a maximum output current of 2 A.