Four-phase Machine Research Articles

Integration of graph network with kernel SVM and logistic regression for identification of biomarkers in SCA12 and its diagnosis.

Spinocerebellar ataxia type 12 is a hereditary and neurodegenerative illness commonly found in India. However, there is no established noninvasive automatic diagnostic system for its diagnosis and identification of imaging biomarkers. This work proposes a novel four-phase machine learning-based diagnostic framework to find spinocerebellar ataxia type 12 disease-specific atrophic-brain regions and distinguish spinocerebellar ataxia type 12 from healthy using a real structural magnetic resonance imaging dataset. Firstly, each brain region is represented in terms of statistics of coefficients obtained using 3D-discrete wavelet transform. Secondly, a set of relevant regions are selected using a graph network-based method. Thirdly, a kernel support vector machine is used to capture nonlinear relationships among the voxels of a brain region. Finally, the linear relationship among the brain regions is captured to build a decision model to distinguish spinocerebellar ataxia type 12 from healthy by using the regularized logistic regression method. A classification accuracy of 95% and a harmonic mean of precision and recall, i.e. F1-score of 94.92%, is achieved. The proposed framework provides relevant regions responsible for the atrophy. The importance of each region is captured using Shapley Additive exPlanations values. We also performed a statistical analysis to find volumetric changes in spinocerebellar ataxia type 12 group compared to healthy. The promising result of the proposed framework shows that clinicians can use it for early and timely diagnosis of spinocerebellar ataxia type 12.

Comparative Research on Four-Phase Dual Armature-Winding Wound-Field Doubly Salient Generator With Distributed Field Magnetomotive Forces for High-Reliability Application

In this article, a four-phase dual armature-winding wound-field doubly salient machine with distributed field magnetomotive forces (DAW-WFDSM-DF) and corresponding double-redundant rectifier circuit are proposed to improve the electromagnetic performance of the traditional WFDSM in terms of the output voltage ripple, fault-tolerant capability and output capability. Firstly, due to the uniformly distributed field magnetomotive forces of the proposed machine, the more feasible stator/rotor pole combinations of the four-phase machine can be obtained and the influence of stator/rotor-pole combination on electromagnetic performance is investigated, especially for the fault-tolerant capability. Based on a multi-objective evaluation function including output capability, fault-tolerant capability and unbalanced magnetic forces, the $4N$ -stator-pole/ $3N$ -rotor-pole ( $4N/3N)$ and $4N/5N$ combinations are recommended. Then, considering that the fault-tolerant capability of 8/6-pole machine is poorer than that of 12/9-pole one, the 12/9-pole and 8/10-pole DAW-WFDSM-DFs are comparatively researched for taking as the representatives of $4N/3N$ and $4N/5N$ , including no-load and on-load characteristics and fault-tolerance performance under single winding open-circuit condition. Finally, as the 8/10-pole DAW-WFDSM-DF exhibits remarkably higher efficiency and stronger fault-tolerant capability than the 12/9-pole one, an 8/10-pole prototype is manufactured and tested to verify the analytical results.

Influence of Geometric Dimensions on the Performance of Switched Reluctance Machine

In a design of a switched reluctance machine, there are a number of parameters that are chosen empirically inside a certain interval, therefore to find an optimum geometry it is necessary to determine how each parameter acts on the performance of the machine. This work presents a study on the influence of geometric dimensions on the performance of the switched reluctance machine. The analysis is done through finite element simulations based on the variation of one parameter while the others are fixed. Graphical and numerical results of torque and magnetic flux are presented for a 6/4 three-phase machine and an 8/6 four-phase machine. The study presented aims to provide consistent data on which dimensions should be modified for specific applications, and thus to base choices made in the design and optimization stage.

Validation and sensitivity of CFETR design using EU systems codes

The Chinese Fusion Engineering Test Reactor (CFETR) bridges the gap between ITER and a fusion power plant (FPP). The primary objectives of CFETR are: ∼2 GW of fusion power, producing ∼700 MW of net electric power, demonstrate tritium self-sufficiency, operate in steady-state and have a duty cycle of 30–50%. CFETR is in the pre-conceptual design phase and is currently envisaged to be a four-phase machine (from phase I Pfus∼200 MW to phase IV Pfus∼2 GW). In 2016 the EU and China began a collaboration on topics relating to nuclear fusion research and one topic of the work is on CFETR and DEMO. This contribution documents the progress on the collaboration on systems codes studies of CFETR. Systems codes attempt to model all aspects of a fusion power plant using simplified models (0-D, 1-D) and capture the interactions between plant systems. This allows the user to explore many reactor designs at a high level and optimise for different figures-of-merit (e.g. minimise major radius, R0, or maximise fusion gain, Q). The EU systems code used for this work is PROCESS, which is the systems code used to create the EU-DEMO baseline designs. This paper details the work on analysing a 2018 CFETR design point in EU systems code PROCESS and the feasibility of the design with regards to meeting the performance objectives and operation of the machine. The work comments on the four-phased nature of the device and the systems code output focuses on phase IV. In combination with the systems code, an uncertainty quantification tool is used to investigate the sensitivity of a CFETR design point to changes in the input assumptions in the systems code. This paper details sensitivities of the CFETR design and shows that given the specified inputs and the uncertainties there are a reasonable number of feasible design points around the CFETR phase IV design point that still fulfil the high-level objectives of the machine.

Excitation Shifting: A General Low-Cost Solution for Eliminating Ultra-Low-Frequency Torque Ripple in Switched Reluctance Machines

Switched reluctance machines (SRMs) suffer from ultra-low-frequency torque ripple in single pulse mode. This ripple is the result of an imbalance in phase currents, when multiphase excitation occurs. This paper investigates the origin of this imbalance and identifies the imbalanced phase. Excitation shifting strategy, which delays excitation of the imbalanced phase, is then proposed. The delay angle adjusts current amplitude in the imbalanced phase to attain a perfect balance between all phases. The excitation shifting strategy is a general solution, which is applicable to both three-phase and four-phase machines. In addition, the proposed method can be implemented by a much simpler drive structure, when compared to the existing balancing methods. Hardware measurements are provided to verify superior performance of the proposed current balancing technique.