PIC microcontroller has a vital role in various types of controllers and nowadays the presence of PIC microcontroller is unavoidable in most control applications. This paper describes the enhancement of soft starting of induction motors using PIC microcontroller. Soft starting is required for the induction motors with reduced applied voltages so that the peak starting current is reduced and the startup of the motor is smooth with controlled torque and reduced mechanical vibrations, reduced starting current with correspondingly reduced bus voltage drops. While many of the available schemes of soft starting offer better results in view of smooth starting process, the proposed methodology offers soft starting as well as it cares about the source current quality. In contrast to the conventional multistep starting scheme, in this work a continuously controlled starting scheme is proposed. The three phase AC voltage controller topology is used as the core controller. In each of the half cycles, instead of a single conduction period with a single delay angle, the proposed AC voltage controller is switched symmetrically in each half cycle with multiple pulses in each quarter cycle. Symmetrically placed fixed numbers of switching pulses are used. The paper also describes the various time ratio controls namely the phase angle controller, the extinction angle controller and the symmetrical angle controller. The design aspects of the proposed soft starting scheme and the validation of the proposed system in the MATLAB SIMULINK environment are presented in this paper.

The mechanical and tribological properties of the Al/CNT composites could be controlled and improved by the method of its fabrication process. This research article deals with the optimization of mechanical and tribological properties of Al/CNT composites, which are fabricated using the mechanical alloying process with the different weight percentage of multi-walled CNT reinforcement. The phase change and the presence of CNT are identified using the X-Ray Diffraction (XRD) analysis. The influence of mechanical alloying process and the multi-walled CNT reinforcement on the mechanical, and tribological behaviours of the Al/CNT composites are studied. The optimal mechanical alloying process parameters and the weight percentage of multi-walled CNT reinforcement for the Al/CNT composite are identified using the Response Surface Methodology (RSM), which exhibits the better hardness, compressive strength, wear rate and Coefficient of Friction (CoF). The Al/CNT composite with 1.1 wt.% of CNT has achieved the optimal responses at the milling speed 301 rpm and milling time 492 minutes with the ball to powder weight ratio 9.7:1, which is 98% equal to the experimental result. This research also reveals that the adhesive wear is the dominant wear mechanism for the Al/CNT composite against EN31 stainless steel but the optimal Al/CNT composite with 1.1 wt.% of multi-walled CNT has experienced a mild abrasive wear.

The paper presents issues associated with the impact of electromagnetic interference on track-side cabinets of a closed-circuit television system (CCTV) functioning in a railway transport environment. The measurements of an electromagnetic field emitted by a track-side CCTV cabinet were presented. Designs of this kind are operated in railway facilities; therefore, they should not disturb the functioning of other equipment, the rail traffic control systems, in particular (so-called inner compatibility). An analysis of the obtained results enabled developing a research model, and a further reliability and operational analysis, taking into account electromagnetic interference. This enabled determining a relationship allowing the determination of the probability of a track-side CCTV cabinet staying in a state of full ability. The presented discussions regarding a track-side CCTV cabinet, taking into account electromagnetic interference, allow for the numerical assessment of different types of solutions (technical and organizational), which can be implemented in order to mitigate the impact of electromagnetic interference on a system’s functioning.

This work evaluates the influence of gate drive circuitry to cascode GaN device’s switching waveforms. This is done by comparing three PCBs using three double-pulse-test (DPT) with different gate driving loop design. Among important parasitic elements, source-side inductance shows a significant impact to gate-source voltage waveform. A simulation model based on experimental measurement of the cascode GaNFET used in this work is modified by author. The simulation model is implemented in a synchronous buck converter topology and hereby to assess the impact of gate driving loop of cascode GaN device in both continuous conduction mode (CCM) and critical conduction mode (CRM). Apart from simulation, a synchronous buck converter prototype is presented for experimental evaluation, which shows a 99.15% efficiency at 5A under soft-switching operation (CRM) with a 59ns dead-time.

Individual identification of similar communication emitters in the complex electromagnetic environment has great research value and significance in both military and civilian fields. In this paper, a feature extraction method called HVG-NTE is proposed based on the idea of system nonlinearity. The shape of the degree distribution, based on the extraction of HVG degree distribution, is quantified with NTE to improve the anti-noise performance. Then XGBoost is used to build a classifier for communication emitter identification. Our method achieves better recognition performance than the state-of-the-art technology of the transient signal data set of radio stations with the same plant, batch, and model, and is suitable for a small sample size.

The development of combustion systems construction is associated with the possibility of increasing the thermal or overall efficiency of an internal combustion engine. The combustion systems currently in use (mainly related to direct fuel injection) are increasingly being replaced by hybrid systems, including direct and indirect injection. Another alternative is the use of prechambers in new combustion systems. This article concerns the thermodynamic aspect of this issue – namely, the assessment of the inter-chamber flow of a marine engine equipped with a prechamber combustion spark ignition system. The research was carried out using mainly one-dimensional simulation apparatus, and detailed analyses were presented using three-dimensional modeling. The tests included the engine model at medium load. Differences in mass flows were shown at different diameters and different numbers of holes from the preliminary chamber (while maintaining the same cross-sectional area). Similar values of excess air coefficient during ignition of the fuel dose in the prechamber were observed, which resulted in changes in the flow between the prechamber and the main chamber. The differences in mass flow affected the temperatures achieved in the individual combustion chambers. Based on three-dimensional analyses, the mass transfer rate between the chambers and the temperature distribution were assessed during fuel ignition initiated in the prechamber.

The article presents a new generation of ultra-fast hybrid switching systems (USH) for reliable, ultra-fast protection of various medium and low voltage DC systems (MVDC and LVDC). The DC switch-off takes place in a vacuum chamber (VC) cooperating with a semiconductor module using current commutation of natural or forced type. Against the background of the current state of science and technology, the paper depicts the basic scopes of USH applications and their particular suitability for operation in high magnetic energy DC circuits. In the case of DC system failures, this magnetic energy should be dissipated outside the system as soon as possible. Usually, magnetic blow-out switches (MBOS) with relatively low operating speed are used for this purpose. The article describes the theoretical basis and principles of construction of two types of novel USH systems: a direct current switching system (DCSS) and a direct current ultra-fast hybrid modular switch (DCU-HM). The DCSS family is designed for quench protection of superconducting electromagnets’ coils in all areas of application. The DCU-HM family is designed for the protection of all systems or vehicles of DC electrical traction and for related industrial applications. The conducted comparative analysis of the effectiveness of USH with respect to MBOS shows clear technical advantages of the new generation switching systems over MBOS. List of abbreviations used in the article is provided at the end.