Rotor Localization and Phase Mapping of Cardiac Excitation Waves Using Deep Neural Networks

The analysis of electrical impulse phenomena in cardiac muscle tissue is important for the diagnosis of heart rhythm disorders and other cardiac pathophysiology. Cardiac mapping techniques acquire local temporal measurements and combine them to visualize the spread of electrophysiological wave phenomena across the heart surface. However, low spatial resolution, sparse measurement locations, noise and other artifacts make it challenging to accurately visualize spatio-temporal activity. For instance, electro-anatomical catheter mapping is severely limited by the sparsity of the measurements, and optical mapping is prone to noise and motion artifacts. In the past, several approaches have been proposed to create more reliable maps from noisy or sparse mapping data. Here, we demonstrate that deep learning can be used to compute phase maps and detect phase singularities in optical mapping videos of ventricular fibrillation, as well as in very noisy, low-resolution and extremely sparse simulated data of reentrant wave chaos mimicking catheter mapping data. The self-supervised deep learning approach is fundamentally different from classical phase mapping techniques. Rather than encoding a phase signal from time-series data, a deep neural network instead learns to directly associate phase maps and the positions of phase singularities with short spatio-temporal sequences of electrical data. We tested several neural network architectures, based on a convolutional neural network (CNN) with an encoding and decoding structure, to predict phase maps or rotor core positions either directly or indirectly via the prediction of phase maps and a subsequent classical calculation of phase singularities. Predictions can be performed across different data, with models being trained on one species and then successfully applied to another, or being trained solely on simulated data and then applied to experimental data. Neural networks provide a promising alternative to conventional phase mapping and rotor core localization methods. Future uses may include the analysis of optical mapping studies in basic cardiovascular research, as well as the mapping of atrial fibrillation in the clinical setting.

SIMULATION AND EXPERIMENTAL RESEARCH OF CLAW POLE MACHINE WITH A HYBRID EXCITATION AND LAMINATED ROTOR CORE

This paper presents the design and research results of a claw pole machine with hybrid excitation. This machine is excited by permanent magnets and an electromagnetic coil. Both excitation sources are located in the rotor of the machine. Additionally, the rotor is made of a laminated core. This approach facilitates the process of its construction and enables the implementation of even very complicated structure of the rotor, which would be difficult in case of making the rotor from a one piece of material. This paper presents the construction as well as the results of simulation and experimental tests of the machine prototype. The tests showed that the proposed machine has the ability to adjust the voltage in a wide range. Such as a feature could be used, for example, to increase the speed of motor operation in case of an electric vehicle application, but also to regulate the voltage in wind turbines which generators operate at varying rotor speeds resulting from changing wind speed.

Design and Development of a Small-Scale Mechanical Energy Conversion Device

This study aims to design and construct a small-scale mechanical energy conversion device. It is designed to produce electrical power by harnessing the available mechanical energy from renewable resources. This study started off with literature review for the predominant principles and laws on how the machine shall be fabricated in order to function. The process is followed by the material selection and analysis before proceeding to the final design and construction. The constructed machine is then being tested through series of experiments. It was found that the small scale device was able to produce 6V of maximum voltage with rotor rotation speed up to 3000 RPM. The outcome from the experimentation shows that the small scale device is useful for power generation from renewable sources, such as stream energy with a micro hydro turbine. For future study, the machine shall consider a few improvements, such as rebuilding it using laminated iron as rotor core and increase the number of poles to enhance the performance of the machine in term of energy conversion and extraction. The design and built of this machine would definitely contribute to the environmental sustainability and development of rural area.