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The permanent magnet linear synchronous motors have the advantages of high efficiency, high thrust density and high power factor, which is mostly attractive to the fields of electromagnetic launch. The electromagnetic field of long primary PMLSM with different structures are analyzed firstly by finite element method in this paper. Then, the thrust characteristics of the motors with different topologies are studied and compared, which fully demonstrates the advantages and feasibility of the proposed PMLSM.

In this article, the hindrance effect of multiple-stage synchronous induction coil launcher (MSICL) during the emission procedure is analyzed. Considering the direction of the coil emission current and induced current, a new method to restrain the hindrance effect is proposed in this work, which can reduce the current operating time and increase the armature exiting speed. Based on this method, an eight-stage SICL is simulated by the finite element algorithm (FEA), including the electromagnetic force, armature speed, and the distribution of the magnetic field, etc., which shows that impact of the hindrance effect can be greatly improved.

In order to improve the thrust density and efficiency of linear induction motors (LIM) in large load transport situations, a cross-shaped linear induction motors (CSLIM) structure is proposed in this paper. Firstly, for analyzing the characteristics of CSLIM, the magnetic field and electromagnetic thrust expression of long primary double-sided linear induction motors (LP-DSLIM) when considering the saturation of iron core are deduced, based on which the effect of iron saturation on electromagnetic thrust is analyzed. Secondary, the equivalent circuit of CSLIM is proposed and the effect of coupling on the electromagnetic thrust is analyzed. The results show that, the maximum electromagnetic thrust is reduced and the corresponding slip frequency is increased when iron saturation and coupling. For improving the problem of iron core saturation and coupling of CSLIM, a structure with square-type iron and lap winding is further proposed, and the rationality of CSLIM structure is verified by comparing the finite element simulation results of flux density on core, eddy current on secondary and the electromagnetic thrust.

Permanent magnet linear synchronous motor (PMLSM) has the advantages of high thrust density and good control accuracy, which can be applied in high-power and high-speed occasions. In this paper, the analytical models are established to obtain the electromagnetic performance for the PMLSMs with dual secondaries and dual primaries. The air-gap flux density and the electromagnetic thrust are also obtained by the finite element model to verify theoretical analysis. Besides, an improved structure is also put forward in order to suppress the thrust fluctuation of the PMLSM. Finally, the advantages and disadvantages of two PMLSMs topologies are listed. These analyses would provide a guide for the design of PMLSMs applied in high-power and high-speed occasions.

In order to meet the rapid transportation of modern ton-level flammable and explosive materials such as oil, there is an increasing demand for the development of electromagnetic transportation systems. For the electromagnetic transportation systems, the linear motor is its core component, which not only requires high thrust density, but also maintains a stable speed during operation, and requires in-depth consideration of electromagnetic compatibility and reliability. In order to ensure the normal operation of the transportation system, according to the actual operating environment and needs, the optimal selection of the motor type is an important factor in determining the performance of the system. In this paper two linear induction motors based on the working conditions that meet the requirements of rapid material transportation are designed by using the magnetic circuit method, namely a bilateral long primary linear induction motor and a bilateral permanent magnet linear synchronous motor. Using the finite element method to compare and analyze the electromagnetic thrust, power factor, efficiency and other performances of the two types of motors in detail. As a result, both motors can better meet the design requirements of the electromagnetic transportation system and have good application prospects. The optimal selection can be made according to the adaptability of the actual application environment, which provides technical support for the optimal design of the electromagnetic transportation system.

Static longitudinal end effect caused by truncated iron and coil windings is the inherent characteristic of linear motors. For multi-segment long primary double-sided linear induction motors (LP-DSLIM), subsection power supply mode result in longer iron than excited coil windings that enhances the static longitudinal end effect, thus aggravating the motor asymmetry. We deduce the analytic expression of pulsating magnetic field and electric potential, and analyze the influence between number of poles, length of end iron on the motor asymmetry. The results show that the motor asymmetry of the even pole motor is enhanced with the increase of end iron length, and is decreased with the increase of the pole number. Theory analysis, which is validated by simulation experiments, could be the reference for the optimal design and performance analysis of LP-DSLIM.

The end effect of the long primary permanent magnet linear synchronous motor (PMLSM) mainly comes from the breaking of the end permanent magnet field, which is a unique phenomenon and problem. This effect has a significant impact on the air-gap magnetic field and the electromagnetic parameters of the motor. Aiming at the end effect of the long primary PMLSM, this paper uses Schwarz-Christoffel transform to establish and solve the long primary PMLSM airgap magnetic field analysis model that takes into account the end effect, the expression of the additional magnetic field is obtained. Moreover, the equivalent circuit model of PMLSM considering the end effect is proposed based on the principle of equal field-circuit complex power, and the end effect reactance is obtained. Finally, the rationality of the end reactance was verified by the finite element numerical calculation, thus proving the validity of the equivalent circuit model that takes into account the end effect.

The direct thrust force control scheme of permanent magnet synchronous linear motor is mainly inspired by the direct torque control of its rotating counterparts so as to achieving excellent force characteristics. However, due to the inherent characteristics of permanent magnet linear synchronous motor, such as open-wide air gap, small equivalent inductance and large mechanical time constant, the control performance of traditional direct thrust control algorithm is greatly deteriorated, which are of prime concern. In this paper, the traditional direct thrust control of permanent magnet linear synchronous motor is analyzed strictly, with the limitations pointed out. Contributed to the concept of predictive control, by optimizing of switching vector and introduction of disturbance observer, the thrust performance of direct thrust force control is improved. At the same time, switching frequency can be optimized, thrust and flux ripple can be suppressed, and outer loop control performance can be improved, when compared to the state of the art.

After organ and tissue injury, the proliferation and differentiation of stem cells themselves play only a small role in the repair of injury, and their repair role is mainly played through the paracrine function of stem cells. Exosomes are nano-scale vesicles that are secreted into the extracellular space in an exocytic manner, and its own function will be regulated after the target cells absorb the exosomes. Stem cell-derived exosomes communicate between cells by transmitting proteins, lipids and micro-RNAs (miRNAs). The targeting and biological properties of stem cell-derived exosomes are determined by the level of miRNAs that they carry. After the exosomes reach the target cells and undergo fusion, the gene expression of the target cells is changed by degradation and expression. In addition, the RNA and protein of stem cell-derived exosomes can also limit the development of injury through cell homing. This article will review the mechanism of stem cell-derived exosomes in wound healing, joint injury, fracture healing and cardiac injury.

A design scheme of a new high-speed high-power permanent magnet linear synchronous motor for the driving source of impact acceleration simulation device is proposed. The electromagnetic properties of no-load back EMF, cogging force, air gap flux density and electromagnetic thrust are calculated by finite element method. The maximum theoretical thrust of the linear motor is obtained. Besides, the characteristic curves of electromagnetic thrust and initial phase angle of current are obtained. The structure of permanent magnet linear synchronous motor is optimized and analyzed. The motor thrusts under different structure scheme are also compared, and a good design scheme of high speed and high power permanent magnet linear synchronous motor is proposed. The research in this paper is of great reference significance to the further research on this type of motor.

The principle of the interception effect of the multistage synchronous induction coil launcher during the launch process is analyzed in this paper. By establishing a finite element simulation model of the multi-stage synchronous induction coil launcher and changing the direction of the discharge current of the last-stage drive coil, the effect of multi-stage synchronous induction coil launcher performance is studied.

Permanent magnet linear synchronous motor (PMLSM) has a good application prospect in the fields of electromagnetic emission. The finite element method is applied to analyze the magnetic field of PMLSM with different permanent magnet (PM) structures. Then, the thrust characteristic of the PMLSM is optimized by PM cutting and Halbach PM, which promotes the study of permanent magnet structure problems in the design of PMLSM.