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We investigated if poly‐lactic acid (PLA) nanopillar array can trigger the differentiation of human epicardial (ADSCs) (heADSCs) into cardiomyocyte‐like cells and explored the effects of these cardiomyocyte‐like cells on myocardial infarction (MI) in vivo. PLA nanopillar array (200 nm diameter) and plain PLA film (PLA planar) induced heADSCs were marked with carboxyfluorescein. After 7 days, the expressions of myocardiocyte‐specific genes were significantly enhanced in cells seeded on PLA nanopillar array compared with that on PLA planar, especially CACNA1C, KCNH2, and MYL2 genes (p < 0.05). However, the expressions of cardiac troponin T (cTNT), KCNQ1, and KCNA5 were lower than those in PLA planar‐induced heADSCs (p < 0.05), whereas GATA4 tended to increase with time. The cells with positively stained α‐actinin and cTNT were elevated in heADSCs induced by PLA nanopillar array compared with those induced by PLA planar only (p < 0.05). In vivo experiments showed that cardiac function was improved after injecting PLA‐nanopillar array‐induced heADSCs into the ischemic heart (p < 0.05, compared with PLA planar + MI group). Furthermore, tyrosine hydroxylase density was significantly lower (p < 0.05). PLA nanopillar array directly drives the differentiation of heADSCs into cardiomyocyte‐like cells, and the induced heADSCs exhibit a protective effect on ischemic myocardium by improving cardiac function in MI rats. [ABSTRACT FROM AUTHOR]

Based on a four‐phase 8/6 structure switched reluctance machine for electric vehicles, the influence of different magnetic pole distributions on iron loss and temperature field is studied here. Firstly, by fitting the core silicon sheet iron loss data of the prototype, a mathematical calculation model of switched reluctance iron loss is constructed. Then, in order to analyse the flux density waveform of the iron core, a 2D finite element model is proposed. Under different magnetic pole distributions, the magnetic flux densities of the iron core are compared and the iron loss is calculated as well. Finally, the simulation results are obtained by establishing the 2D finite element thermal model of the prototype and analysed. Then, the experimental test platform is built and experimental data are recorded and analysed. By comparing the experimental results, it is found that the temperature rise is well consistent with the temperature rise of the 2D finite element thermal model. [ABSTRACT FROM AUTHOR]

In this study, the design optimisation of a switched reluctance machine (SRM) with the layered method has been studied. Firstly, a multi‐physical analytical model for the SRM is established. The proposed model consists of an electromagnetic model, an electrical model, a loss model, and a thermal model. Then a layered optimisation design method suitable for the SRM is proposed in combination with the multi‐physical field simulation model. Taguchi method is used to analyse the influence degree of the main geometric dimensions on the dynamic performance, and the parameters are divided into high‐sensitivity parameters (HSPs) and low‐sensitivity parameters. The non‐dominated sorting genetic algorithm‐II algorithm is used to optimise the HSP by the proposed model. The iron loss, average torque, average torque per unit mass, torque ripple and efficiency are taken as the objective functions. Finally, the prototype is manufactured and a testing platform is built. The flux linkage of several special positions of the machine is verified experimentally, and the accuracy of the electromagnetic model in the multi‐physical field model is verified. The temperature experiments are carried out on the machine, and the accuracy of the equivalent heat circuit model in the multi‐physical field model is verified. [ABSTRACT FROM AUTHOR]

This study sets forth an equivalent electric circuit (EEC) model including core losses and phase interactions to obtain a more accurate steady and dynamic performance of the high speed switched reluctance motor (SRM) during the design, analysis, and control of the SRM drive system. The magnetic equivalent circuit (MEC) method is used to calculate the flux linkage and torque quickly and relative accurately. Based on the principle of transformation between the MEC and EEC, the EEC model is derived from the MEC model. To enhance the model precision, the dynamic core losses and phase interactions are analysed and added to the EEC model. The relationship between the phase current and virtual current corresponding to different parts is deduced. Then the simulation model of the whole SRM driver systems is established in MATLAB/Simulink to obtain the phase current and virtual current corresponding to a different portion. The experimental and simulated results of the static MEC model and the whole SRM drive system including the EEC model provide the conclusive evidence for validating their practicability. [ABSTRACT FROM AUTHOR]

A fast method to calculate the iron loss of switched reluctance motor (SRM) is proposed. The key of the method is that the flux density waveforms in different parts of the motor can be obtained quickly. First, the static flux density data varying with phase current and rotor position in various parts of SRM are obtained by finite element method (FEM). Then, the static flux density data are stored in 2D look‐up tables in Matlab/Simulink to get the flux density waveforms by look‐up table method, and the obtained flux density waveforms are verified by FEM results. Since the flux waveforms are non‐sinusoidal and non‐linear, an accurate and fast model for the iron loss prediction is presented, and different modified factors are applied to calculate the hysteresis loss according to the classification of flux density waveforms. Based on that, the calculation model is established in Matlab/Simulink, and iron losses of a three‐phase 6/4 structure SRM under different turn‐on and turn‐off angles and load conditions are calculated and analysed. Finally, measured results are presented to verify the precision of the calculation model. [ABSTRACT FROM AUTHOR]