Nano-Modified Meta-Aramid Insulation Paper with Advanced Thermal, Mechanical, and Electrical Properties

Molecular dynamics simulations were used to analyze the internal mechanism for the observed improvement in performance of nano-modified meta-aramid insulation paper from a microscopic point of view. The results showed that the k-polyphenylsilsesquioxane(PPSQ) modified meta-aramid insulation paper was superior to b-PPSQ modified meta-aramid insulation paper in terms of its thermal stability and mechanical and electrical properties. The analysis of microscopic parameters showed that the stiffness of k-PPSQ was less than that of b-PPSQ, and the hydroxyl groups on the open-loop system were more likely to enter the dispersed system, resulting in higher bonding strength, meta-aramid fiber chains between k-PPSQ molecules, and the formation of hydrogen bonds. Additionally, the nano-enhancement effects of k-PPSQ and b-PPSQ resulted in various improvements, including a reduction in pores between molecules in the blend model, an increase in the contact area, the formation of interfacial polarization, and a reduction in defects at the interface.

ALGORITHM FOR SELF-TUNING THE PID CONTROLLER

An algorithm for self-tuning the PID controller to the second order systems is proposed in this paper. The proposed self-tuning procedure was developed according to the maximum stability degree criterion, the criterion that permits to achieve the high stability degree, good performance and robustness of the system. According to the proposed algorithm, the controller can be tuned according to the parameters that characterize the process and they can be determinate from the experimental response of the open loop system. To demonstrate the efficiency of proposed procedure of self-tuning the PID controller, the computer simulation was performed and the obtained results were compared with Haeri’s method, maximum stability degree method with iterations and parametrical optimization method. According to the developed algorithm, it was performed the control of the thermal regime in the oven.

Anti-sway method for reducing vibrations on a tower crane structure

We develop a solution to the problem of the behavior of a tower crane considered as a deformable system, and therefore subject to vibrations, whereas the controlled movement of a payload is implemented. The motion of the payload is calculated taking into account the normal vibration modes of the tower crane and the swaying of the payload. A “command smoothing” method relative to an open-loop system is used for reducing the sway of the payload, through smoothing the original command by the crane operator. This leads, as a consequence, to a reduction in the vibrations of the crane structure. An iterative calculation of the sway angle and the corresponding applied velocity profiles as input to the crane motors is applied. The tower crane is considered as a high nonlinear underactuated system; it is modeled considering the possible deformation of the structure. The results relating to the normal deformations of the crane are obtained, highlighting how these vibrations are strongly attenuated when an anti-sway system for the payload is implemented. Therefore, it is shown how this control leads to the best results in terms of performance for both the payload movement (shortest possible profile for the rotation movement and damping of the load oscillation) and the structure of the tower crane. Applying the method described in this paper, the structure of the tower crane does not undergo the strong horizontal and vertical oscillations that occur when the elastic structure is not considered in the crane model.

Passive system of cooling and refrigerant fluid circulation, assisted by capillary pumping

We propose a concept design of a cooling system, primarily targeting gas-insulated switchgear enclosures which use a mixture of a refrigerant fluid, such as Novec™ 649, and a non-condensable gas for electrical insulation. The novel open-loop system relies on evaporative cooling assisted by capillary pumping, and refrigerant vapor condensation on the walls of the system enclosure. The results of experiments on a laboratory prototype are presented and discussed. Besides cooling, a major benefit of the system is in facilitating the circulation of the gas mixture in the enclosure.

Cost of Controls for Multi-Rotor Drones

This paper focuses on the energy costs of using a control system to follow a specific trajectory as opposed to directly choosing the inputs in an open-loop sense to achieve a specific trajectory. Results show that the PID controller will use 7–13% more energy than the open-loop system for the small-amplitude trajectories and 62–74% more energy for the high-amplitude trajectories while maintaining trajectory errors of approximately 5% and 19%, respectively. The PD controller will use 0.03–0.04% less energy than the open loop system for the small-amplitude trajectories and 0.35% less energy for the high-amplitude trajectories while maintaining similar trajectory errors to the PID controller. The two trajectories have different trajectory errors (5% vs. 19%). Therefore, the controller does not have to move the rotor speeds to the same level, thus causing more energy saved for the large-amplitude trajectory. Based on these simulations, it can be concluded that the PD controller will be significantly more energy efficient than the PID controller while maintaining similar trajectory errors throughout the entire flight. This is because the integral control term in the PID controller accumulates the error so any initial large errors in the position will result in large controller inputs later in the flight. The accumulation of error in the integral term then results in large variations in rotor speed which often leads to a higher energy usage. Thus, a PD controller may be a more energy efficient choice while maintaining effectiveness in trajectory-tracking. These results highlight the importance of considering and comparing the energy costs of various control systems when designing controllers for multi-rotor drones.

FEATURES AND PRINCIPLES OF THE DEVELOPMENT OF BRUSHLESS MAGNETOELECTRIC SYSTEMS OF THE RETURN-ROTARY MOTION

The paper reviews the results of studies of brushless magnetoelectric systems of return-rotary motion, carried out for many years at the Electrodynamics Institute of the National Academy of Sciences of Ukraine. Structures of specialized brushless magnetoelectric motors with elastic magnetic coupling between the stator and the rotor are presented. An example of structural optimization of the motor is given. The electromechanical characteristics of the motors of the return-rotary motion are described and the indexes of their efficiency are proposed. An example of the formation of functional dependences for motor control in an open-loop system is given. Structures of the system for automatic control of the rotor oscillations angle amplitude and stator current limitation, as well as a system for vector control of the auxiliary winding current for active compensation of reactive alternating torque of the main rotor are presented. Examples of calculation of transient responses of the main parameters of the motor are given. Reference 11, figure 9.

FREQUENCY CHARACTERISTICS OF BRUSHLESS MAGNETOELECTRIC MOTORS OF RETURN-ROTARY MOTION

n this paper, the frequency characteristics of a special brushless magnetoelectric motor of return-rotary motion with sinusoidal and rectangular forms of the carrier signal are investigated. The method of generating a feedback signal on the amplitude of the rotor shaft oscillations angle has been improved by fixing the value of the signal at the moment of reaching its amplitude. The method of calculating the control system of the oscillations angle amplitude is investigated based on the frequency characteristics of the open-loop system by setting the phase stability margin. Examples of the calculation of transient processes of regulation of the oscillations angle amplitude and the effective value of the stator current when starting the motor and changing the mechanical load are given. References 9, figures 6, tables 2.

Portable Gantry Crane Payload Angle Limitation Control with the Presence of Trolley Position Vibration using Optimal Control

In this paper, a portable gantry crane is designed and controlled with the presence of trolley vibration disturbance using robust control technique. In the open loop system, the payload angle is not stable in both the impulse and step input force signals. Comparison of the system with H 2 and μ - synthesis controllers have been done for a step and impulse input force signal and a promising results have been analyzed.

Design and Simulation of a Steam Turbine Generator using Observer Based and LQR Controllers

A steam turbine generator is an electromechanical system which converts heat energy to electrical energy. In this paper, the modelling, design and analysis of a simple steam turbine generator have done using Matlab/Simulink Toolbox. The open loop system have been analyzed to have an efficiency of 76.92 %. Observer based & linear quadratic regulator (LQR) controllers have been designed to improve the generating voltage. A comparison of this two proposed controllers have been done for increasing the performance improvement to generate a 220 DC volt. The simulation result shows that the steam turbine generator with observer based controller has a small percentage overshoot with minimum settling time than the steam turbine generator with LQR controller and the open loop system. Finally, the steam turbine generator with observer based controller shows better improvement in performance than the steam turbine generator with LQR controller.