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118 results on '"Zakis, Janis"'

3. Dynamic Resonant-Inductive Wireless Power Transfer System for Automated Guided Vehicles with Reduced Number of Position Sensors.

Author

Stepins, Deniss, Sokolovs, Aleksandrs, and Zakis, Janis

Subjects
AUTOMATED guided vehicle systems, WIRELESS power transmission, POSITION sensors, SENSOR placement, MICROCONTROLLERS, MAGNETIC sensors, ELECTRON tube grids
Abstract

This paper deals with the position detection of automated guided vehicles (AGVs) in dynamic resonant-inductive wireless power transfer (WPT) systems. A position detection is necessary to activate the correct transmitting coil. One of the simplest and most effective approaches for a position detection method is to use optical or magnetic position sensors for each coil. However, due to needing a high number of sensors, this technique is relatively expensive. Therefore, an AGV position detection technique based on a reduced number of optical or magnetic sensors (by a factor of two) is proposed. The proposed detection technique was verified experimentally by using a scaled-down prototype of the dynamic WPT system. The proposed approach can be easily implemented by uploading a specific program code to a microcontroller. The microcontroller with the code developed by us was used for processing data from AGV position detection sensors, activating a suitable transmitting coil and controlling an inverter of the dynamic WPT system. As shown by the experiments, due to the proposed approach for the position detection of AGVs and activation of transmitting coils, the number of the position detection sensors is reduced by a factor of two, leading to reductions in the overall cost and level of complexity of the dynamic WPT system without degrading its performance. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Air‐Stable Bis‐Cyclometallated Iridium Catalysts for Ortho‐Directed C(sp2)−H Borylation.

Author

Zakis, Janis M., Messinis, Antonis M., Ackermann, Lutz, Smejkal, Tomas, and Wencel‐Delord, Joanna

Subjects
*IRIDIUM catalysts, *BORYLATION, *IRIDIUM
Abstract

We report a class of isolable bis‐cyclometallated iridium precatalysts (ImIr) and their use in regioselective ortho−C−H borylation of aromatic, heteroaromatic, acrylic, and aliphatic systems. The catalysts consist of two imine ligands and an acetate coordinated to an iridium (III) center. The isolable character of ImIr warrants its compatibility with high‐throughput experimentation, a prerequisite for applications in late‐stage functionalization (LSF) of complex substrates. Initial mechanistic studies point towards an inner‐sphere mechanism involving bis‐cyclometallated species shedding light on the general mechanistic understanding of ortho‐selective C−H borylations. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Current Sensorless Control Algorithm for Single-Phase Three-Level NPC Inverter

Author

Suzdalenko Alexander, Zakis Janis, and Steiks Ingars

Subjects
sensorless control, current control, pulse width modulation inverters, Electrical engineering. Electronics. Nuclear engineering, TK1-9971
Abstract

The current measurement is becoming a challenging task in power converters operating at high switching frequencies, moreover traditional control system requires two control loops - first (slow) regulates DC-link voltage, second (fast) controls the shape of current, that all together results in complicated transfer function and long transition periods. The current sensorless control (CSC) allows neglecting the mentioned problems. This research for the first time presents the solution of CSC implementation in single-phase three-level neutral point clamped inverter. Mathematical equations were defined for inductor current peaks and transistor conduction time during discontinuous and continuous conduction modes, as well as major problem of current fitting between different voltage levels (consequently with different current peak-to-peak values) was solved, providing two solutions - pre-fitting and post-fitting trajectories. The verification of our theoretical assumptions and analytical equations was confirmed by the simulation analysis. Challenges of real experiments are discussed in the conclusion.

Published
2014
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