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The BRCA2 tumor suppressor protects genome integrity by promoting homologous recombination-based repair of DNA breaks, stability of stalled DNA replication forks and DNA damage-induced cell cycle checkpoints. BRCA2 deficient cells display the radio-resistant DNA synthesis (RDS) phenotype, however the mechanism has remained elusive. Here we show that cells without BRCA2 are unable to sufficiently restrain DNA replication fork progression after DNA damage, and the underrestrained fork progression is due primarily to Primase-Polymerase (PRIMPOL)-mediated repriming of DNA synthesis downstream of lesions, leaving behind single-stranded DNA gaps. Moreover, we find that BRCA2 associates with the essential DNA replication factor MCM10 and this association suppresses PRIMPOL-mediated repriming and ssDNA gap formation, while having no impact on the stability of stalled replication forks. Our findings establish an important function for BRCA2, provide insights into replication fork control during the DNA damage response, and may have implications in tumor suppression and therapy response.

A typical flywheel energy storage system (FESS) includes an electrical machine, a flywheel, and magnetic bearings, which are independent of each other. Therefore, the structure of FESS is complicated, which leads to the problems of high cost and low integration. This article presents a novel stator PM excitation solid rotor machine (SPE-SRM) for FESS, which integrates an electrical machine, flywheels, and a magnetic bearing. The design method of the SPE-SRM is presented specifically. First, the structure and operation principle of the SPE-SRM are illustrated. Second, the design and optimization of the flywheel-rotor are presented with considering of power, energy storage, and mechanical strength. Third, the magnetic equivalent circuit of the SPE-SRM is established to simplify the design. Besides, the armature reaction and leakage flux factor are investigated. Fourth, the performance indexes, including torque, suspension force, no-load back electromotive force (back-EMF), losses, and temperature rise are fully analyzed by the finite element analysis. Finally, a 22 kW prototype is manufactured and tested. The rationality of the concept and design is validated by experiments. The SPE-SRM has the merits of high integration, robust structure, and low cost, so it has the potential for wide application in FESS. [ABSTRACT FROM AUTHOR]

Homopolar inductor machine (HIM) has caught much attention in the field of flywheel energy storage system (FESS) due to its merits of robust rotor, brushless exciting, and high reliability. Compared with permanent magnet HIM (PM-HIM), the HIM with field winding (FW-HIM) can effectively eliminate the idling loss caused by the no-load magnetic field by cutting off the excitation current, while the charge/discharge efficiency of the HIM would be decreased due to the copper loss of field winding. To address this contradiction, a novel PM-HIM with a mechanical flux modulator (MFM-HIM) is proposed to achieve low idling loss and high charge/discharge efficiency. First, the special structure and operation principle of the MFM-HIM are investigated. Afterwards, the characteristic of the equivalent magnetic circuit of the MFM-HIM is analyzed and the key structure parameters of it are derived and optimized. Moreover, the electromagnetic performance indexes of the MFM-HIM, including back electromotive force, flux weakening ability, losses, etc. are fully analyzed. Finally, a prototype of the MFM-HIM is designed, manufactured, and tested. Experiment results confirm those obtained by simulations. Results show that the proposed MFM-HIM inherits the merits of high charge/discharge efficiency of PM-HIM and almost no idling electromagnetic loss of FW-HIM. The MFM-HIM could be a promising candidate for the application of FESS. [ABSTRACT FROM AUTHOR]

The urban rail transit system has the characteristics of wide voltage fluctuation, intermittent and strong impact load, limited heat dissipation capacity. The high-speed flywheel energy storage system (FESS) is used to provide network voltage stability and regenerative braking energy recovery due to its high power density, unlimited number of charge-discharge cycles, fast response and environmental friendliness. When considering the design of high-speed FESS converter with 3.6 kHz fundamental frequency and 330 kW rated power used in 1500 VDC urban rail transit system, the two-stage topological converter reduces the efficiency and increase the cost and size, meanwhile, the series-connected converters and the multilevel converter increase the difficulties of control and insulation, so the two-level and I-type three-level converters of high-speed FESS are designed and evaluated. Several comparisons are made by detailed experimental data from the perspective of the traction load characteristics of the 1500 VDC urban rail transit system and the technical and economical requirements of the high-speed FESS. It is found that the three-level converter has significant advantages in matching the traction load characteristics for its higher duty cycle capability, as well as improving the technical and economical performances such as efficiency, du/dt value, THD, voltage stability, and reducing the cost by 40% when compared to the two-level converter. While in the future MW class high-speed FESS development, the maximum output power capacity of the three-level FESS is relatively lower than that of the two-level FESS. The theoretical analyses were verified by experiments. [ABSTRACT FROM AUTHOR]

Homopolar inductor machine (HIM) has been applied in the field of flywheel energy storage system (FESS) due to its merits of simple structure, high reliability, and low idling losses. However, the HIM features unipolar air-gap flux density, which makes its power density lower than that of the electrical machine with bipolar air-gap flux density. Addressing this issue, a novel outer rotor homopolar inductor machine (OR-HIM) is proposed in this article. First, the special structure and operation principle of the OR-HIM are illustrated. Then, the unit motors of the OR-HIM are obtained and investigated based on the magnetic equivalent circuit method to facilitate the design. Moreover, the performance indexes, including power density, output characteristics, losses, and rotor stress of the OR-HIM, are fully analyzed. Finally, a 13-kW prototype is designed, manufactured, and tested. The back electromotive force, load voltage, output torque, and efficiency are measured and compared with those obtained by the finite element analysis. The results indicate that the proposed OR-HIM is a promising candidate for the application of FESS. [ABSTRACT FROM AUTHOR]

An air-core compensated pulse alternator is a compact pulsed power supply for electromagnetic launchers. The structures of these machines are designed distinct from that of traditional synchronous generators. The materials used to build rotor and stator are non-ferromagnetic instead of the traditional ferromagnetic materials. They are usually designed slotless to enhance the stiffness of coupling of windings. As a result, the method of windings inductance calculation is different from that of the traditional ones. The parameter of windings inductance of air-core compensated pulsed alternator plays an important role in the machine design and performance simulation. Therefore, an analytical method to calculate the windings inductance is needed. In this paper, two analytical methods, a 2D method and a 3D method, are used to calculate the windings inductance. As to the special figuration of these windings, a 2D analysis method based on the parallel two-conductor line electromagnetic theory and the superposition principle is employed to calculate the self-inductance and the mutual-inductance of them. Then, a 3D analytical method based on the theory of mutual-inductance between two parallel rectangular loops whose central axes are the same is presented. Finally, a finite-element method based on the software ANSYS is also used to calculate the inductance, which is used to verify the accuracy of the analytical methods. Index Terms--Air-core machine, compulsator, inductance calculation, pulsed alternator, winding design.

Brushless structure is beneficial for air-core compensated pulsed alternator (ACPA) because its field current and rotation speed are too large for the slip rings and carbon brushes. To achieve the brushless structure, a cascaded brushless self-excited ACPA (CBSACPA), which consists of an exciter and a generator in cascade, is proposed, in this article. The exciter and generator have a common rotor. A novel squirrel-cage rotor winding (SCRW), which can eliminate the end winding compared with conventional wound rotor winding (WRW), is proposed to simplify the rotor structure and improve the performance. First, the structure of the CBSACPA with the SCRW is introduced. Second, the operation principles of the machine are elaborated. Third, the dynamic mathematical model is presented. Fourth, the operation principles are demonstrated by the finite-element method. In addition, the performance of the SCRW is compared with the WRW as well. Finally, a prototype of CBSACPA is developed and tested to validate the analyses and simulations. In conclusion, this study gives detailed introduction, analyses, and validation about the CBSACPA, which provides a new solution to achieve a brushless structure for the ACPA. [ABSTRACT FROM AUTHOR]

This article presents the design and analysis of a 12/7 (numbers of stator/rotor poles) hybridly excited asymmetric stator pole doubly salient machine (HEASPDSM) with a main focus on the special topology and operational principle by using the analytical and 2-D finite element analysis. A full comparison is conducted on the average torque, torque ripples, no-load back electromotive force and flux regulation capacity under the condition of different structural parameters, which can provide good references to the machine design. A 12/7 HEASPDSM is designed and the main performance indexes are analyzed in detail. Based on the parameters, the performance of 12/7 HEASPDSM is compared with traditional 6/7 doubly salient permanent magnet machine (DSPMM) with the same volume and thermal load. Finally, a prototype of the 12/7 HEASPDSM is manufactured and tested to validate the theoretical analysis. The results fully demonstrate that the HEASPDSM possesses the merits of strong flux regulation capability, higher torque density, and wider constant power speed range benefitted from the dc field winding than the traditional DSPMM. [ABSTRACT FROM AUTHOR]

The homopolar inductor machine (HIM) has attracted recent interest in the field of flywheel energy storage system due to its merits of robust rotor and low idling losses. In some situations, the analytical methods of a conventional wound-field synchronous machine (WSM) can be used to analyze the HIM, but the clear explanation about why these can be done and the relationship between HIM and WSM were not given in the literature. To address these issues, this paper studies the HIM based on the basic theoretical model and equations. First, the structure and magnetic circuit characteristics of HIM are introduced. Second, the mathematical model of HIM is derived and then decomposed, which indicates that the HIM can be seen as a WSM with large end leakage inductance when rotor tooth width $ {\theta _t} \leq \pi /p$ , or a combination of WSM and synchronous reluctance machine (SynRM) when ${\theta _t} > \pi /p$. Third, the performance indexes of HIM and corresponding equivalent machines, including air gap flux density, back electromotive force, and inductance parameters, are analyzed and fully compared. Finally, an HIM is prototyped and tested on an experimental platform. The simulation and experiment results show that it is reasonable to regard the HIM as a WSM or a combination of WSM and SynRM. The conclusion gives a transparent explanation about the relationship between HIM and WSM, which helps to simplify the analysis of the HIM. [ABSTRACT FROM AUTHOR]

Homopolar inductor machine (HIM) has a wide range of applications in the field of flywheel energy storage system and ship propulsion due to its merits of simple structure, brushless exciting, and low idling losses. However, the three-dimensional finite element method (3-D FEM) is mainly used to investigate the electromagnetic performance indexes of HIM due to its intrinsic 3-D flux density distribution, which is time-consuming. To facilitate the analysis of HIM, an analytical method (AM) is necessary, especially in the initial design stage. Hence, this article presents an AM for analyzing the electromagnetic performance of HIM. First, the structure and operation principle of HIM are illustrated. Second, the magnetic equivalent circuit of HIM is built considering the saturation of stator and rotor core. Third, the air-gap permeance function is obtained considering the affection of stator and rotor slots. Finally, the magnetomotive force, air-gap flux density, back electromotive force, inductances and electromagnetic torque of HIM are calculated, then validated by 3-D FEM and corresponding experiments. The results indicate that the proposed AM can provide reasonable results to estimate the electromagnetic performance of HIM, which would be helpful for the analysis of HIM. [ABSTRACT FROM AUTHOR]

A novel hybrid excited asymmetric stator pole doubly salient machine (HEASPDSM) is proposed in this paper. The new topologies and operational principle are first investigated by using a simplified equivalent magnetic circuit model. The harmonic components of air-gap flux density are then analyzed. The influence of key structural parameters of the proposed machine on the flux regulation ability and torque is studied. A full comparison on main electromagnetic performance indexes of the proposed 12/7 (stator/rotor poles) HEASPDSPM and several traditional doubly salient machines is presented. A prototype is fabricated and tested to validate the theoretical analysis. The results well demonstrate that the HEASPDSPM possesses various merits, such as strong flux regulation capability, high torque density, low cogging torque, and low torque ripple. [ABSTRACT FROM AUTHOR]

A novel brushless self-excited air-core compensated pulsed alternator (BSACPA) is presented in this paper. It consists of two submachines in cascade, among which one serves as an exciter and the other works as a generator. The rotor windings of the two submachines are connected by a reverse phase sequence to realize reversal of the magnetic field. The stator windings are connected by a rectifier to realize the brushless self-excited structure. As an air-core compensated pulsed alternator (CPA) of new topology, it is necessary to derive its mathematical model and carry out a comparative design. Thus, this paper focuses on the detailed design and analysis of a BSACPA prototype, which includes dimensional design and equivalent circuit establishment. In addition, the critical speed is also acquired. Accordingly, the numbers of winding coil turns are designed to increase the discharge current and power based on the theoretical analysis. Finally, the analysis and design are verified by finite-element analysis (FEA). [ABSTRACT FROM AUTHOR]

Pulsed power technology is widely used in medical treatment, military, and scientific research, such as laser burst and electromagnetic launch. Compensated pulsed alternator (CPA) is a kind of device generating that pulsed power. One of the shortages for the air-core pulsed alternator is the huge excitation loss. In order to solve the problems, a multidisk axial flux CPA (MAFCPA) is proposed, which replaces the excitation windings with permanent magnets, saving the self-excitation process. In addition, multidisks are designed, especially to reduce subtransient reactance when the CPA discharges, which contributes to increasing the discharging current. This paper mainly focuses on researching the feasibility of MAFCPA in aspects of thermal issues, rotor statics, and dynamics problems. First, the topology and principle of MAFCPA are introduced, and the properties of the materials are listed as well. Second, the loss of discharging is calculated and the temperatures of both stator and rotor are solved. Then, the maximum stresses of different materials are obtained. Afterward, the critical speeds are researched in order to avoid resonance. Finally, the conclusion is made that MAFCPA can work safely under a speed of 10000 r/min and supply a pulse of over 50 ms. [ABSTRACT FROM AUTHOR]

The compensated pulsed alternators (CPAs) have good applications in high-energy lasers, electromagnetic rail guns, and other electromagnetic launch devices. Among various electrical machine topologies, homopolar inductor alternators (HIAs) have attracted interest as CPAs due to their merits of simple and reliable structure, brushless excitation, and high-speed operation. However, the length of the conventional HIA is difficult to expand because it is limited by the rotor diameter, and the rotor diameter is restricted by the maximum speed of rotor tip, which results in low-energy storage capacity of a single machine. Besides, HIA suffers from the relatively low-power density due to its unipolar air-gap flux density (UAFD). To solve these problems, two novel HIAs with multistage stator cores (HIA-MSCs) are proposed in this paper. One is HIA with UAFD (HIA-UAFD) and the other is HIA with unipolar and bipolar air-gap flux density (HIA-UBAFD). First, the structure and operation principle of HIA-MSCs are illustrated. Then, the key parameters of HIA-MSCs are derived, and the corresponding models are built. Finally, the electromagnetic performances of HIA-MSCs are investigated by 3-D finite-element analysis method. Compared with HIA-UAFD, HIA-UBAFD has relatively higher discharge current and output power, which indicates that HIA-UBAFD is a better candidate for the pulsed alternator. [ABSTRACT FROM AUTHOR]

Air-core compensated pulsed alternator (ACPA) has been applied to the field of pulsed power technology, especially electromagnetic launch. The high-field current and the rotating speed of the ACPA bring the benefits of high power and energy density, but also make it suffer from low reliability and poor performance due to the serious heat and wear in the slip rings and brushes. To solve this problem, a novel brushless self-excited ACPA (BSACPA) is presented in this paper. It consists of two submachines in cascade, namely, an exciter and a generator, for which the air-gap flux rotation directions are opposite. The rotor windings are specially arranged and adopt the principle of negative sequence alternate current excitation, thus eliminating brushes and slip rings, and no rotary rectifier diode is needed. First, the structure and the operation principle of the BSACPA are described. Second, the magnetic field distribution and the coupling between the two submachines are analyzed. Third, the mathematical model of BSACPA is established. Finally, the validity of its operation principle is verified by finite-element and circuit analyses. In conclusion, BSACPA achieves the brushless structure and provides a new solution to improve the performance and the reliability of a conventional ACPA. [ABSTRACT FROM AUTHOR]

Homopolar inductor machines (HIMs) are promising candidates of the pulsed alternator for the application of high power pulsed supplies. However, a single HIM can hardly serve as both a pulsed alternator and a motor, because the voltage and frequency of the pulsed alternator are usually much higher than those of the motor. Thus, a prime motor is needed to drag the pulsed alternator, which makes the pulsed alternator system rather complex. To simplify the structure of the system, this paper proposes a novel four-stator-core HIM (FSCHIM) consisting of an alternator and a motor. First, both the configuration and operation principle of the FSCHIM are introduced. Second, the sizing equations of the FSCHIM are deduced to obtain its primary size parameters. Third, the armature reaction is investigated and the influences of main structure parameters on key output indices are studied by using finite-element analysis (FEA). Finally, the optimized scheme is validated by three-dimensional FEA and experimental results on the subelectrical machines. The results demonstrate that the FSCHIM can serve as a combination of the motor and the pulsed alternator, which enjoys the merits of high-voltage and high-frequency discharge performance with a lower voltage and lower frequency driving system. [ABSTRACT FROM AUTHOR]

An axial-flux permanent-magnet (PM)-assisted claw-pole generator (APCG) is designed based on an equivalent magnetic circuit model (EMCM). It is designed for generating power in vehicle with the merits of high power density, no brush, and wide airgap flux density modulation range. This paper mainly focuses on establishing the EMCM of the APCG and designing a set of optimal structure parameters. First, the topology and operation principle of the APCG are introduced in detail, including material, fabrication, and magnetic flux distribution. Second, the magnetic circuits in claw poles are simplified and the relationships among the key parameters are discussed. Finally, based on the simplified model and the relationships among the key parameters, the EMCMs of current and PM excitation are established, respectively. According to the EMCM, a scheme of a 4 kW APCG is carried out. Comprehensive investigations demonstrate that the EMCM is time-saving and relatively accurate when compared with a finite element method. [ABSTRACT FROM AUTHOR]

An automobile generator has stringent requirements on its weight and volume. As a combination of permanent magnet and electric excitation motor, hybrid excitation machine has the merits of small size, lightweight, and adjustable output voltage, which can meet the requirements of the vehicular generator. In this paper, a novel axial flux stator partition hybrid excitation brushless synchronous generator (ASHG) is proposed. First, the structure and the operating principle of ASHG is illustrated. Afterward, the shape of the magnetic pole is optimized to obtain the air-gap flux density with low harmonic component. Finally, the regulation performance of the magnetic field and output voltage are investigated by using the 3-D finite-element analysis method. The result indicates that the ASHG has a good ability to adjust the terminal voltage. [ABSTRACT FROM AUTHOR]

The homopolar inductor machine (HIM) is of particular interest in the field of flywheel energy storage system, where it has the potential to significantly reduce self-discharge associated with magnetic losses. However, the conventional HIM suffers from low power and torque density due to its unipolar air-gap flux density. Besides, the air-gap flux density of HIM is limited by the cross section of rotor, and the rotor diameter is limited by the maximum tip speed of the rotor. Thus, the maximum effective length and diameter of rotor should be within a certain range, which constrains the output power and stored energy of the HIM. To solve these problems, a novel multi-unit out-rotor HIM (MO-HIM) with bipolar air-gap flux density is proposed in this paper. First, the structure and operating principle of MO-HIM is illustrated. Then, the characteristics of the proposed machine are analyzed, indicating that MO-HIM can be regarded as a superposition of multiple unit machines. Finally, to verify the superior performances of the proposed MO-HIM, it is compared with a unipolar out-rotor HIM with multi-segment stator cores in terms of air-gap flux density, back electromotive force, and output torque. Results show that the proposed MO-HIM has larger fundamental air-gap flux density, higher power, and torque density. [ABSTRACT FROM AUTHOR]

Doubly salient permanent magnet machine (DSPMM) has received extensive attentions recently due to its simple structure, high reliability, high torque density, etc. An improved 4/4 stator/rotor single-phase asymmetric-stator-pole DSPMM is proposed in this paper. First, it has investigated the topologies and operating principle based on torque expression and graphical description. Then, the effect of key structure parameters on torque is studied based on the 2-D finite-element algorithm. And then, comprehensive comparison on electromagnetic torque for the original and new machines is made. Finally, one prototype for the improved structure is manufactured and tested. It indicates that lower cogging torque, lower torque ripple, and stronger starting capability can be obtained by the improved structure. The theoretical results are well validated by comprehensive experiments. [ABSTRACT FROM AUTHOR]

The torque ripple is a main source of the noise and vibration which has a considerable effect on the performance of the machine. A design technique, tooth notching, which was extensively used in permanent magnet machines, has been innovatively applied to a wound‐rotor brushless doubly‐fed machine (BDFM) to reduce the torque ripple. First of all, the winding structure, the winding space harmonics and magnetic fields of the stator and the rotor were studied. Then, general analytical expressions of the electromagnetic torque (EMT) for the BDFM were deduced. Finally, prediction of the results was verified by several models which were calculated by the finite‐element analysis method, meanwhile, the influences of different tooth‐notching structures and the notch depth on the EMT were investigated. It is shown that the torque ripple can be reduced by the suggested design with small increment of the magnetic field saturation and the currents of the control winding and the rotor winding. [ABSTRACT FROM AUTHOR]

In this paper, one novel heteropolar radial hybrid magnetic bearing (HRHMB) with low-power loss is proposed for flywheel energy storage system. First, its structure and equivalent magnetic circuit (EMC) are introduced in detail. Then, some main design parameters are analyzed based on EMC, including air-gap bias flux density, magnetic pole area, permanent magnet (PM) dimensions, and control current. Furthermore, to improve the performances of the novel HRHMB, the optimizations are implemented both on its structure and some key size parameters, such as the second air-gap length, PM height, and width. Finally, the optimal scheme is verified by the 3-D finite-element analysis, which indicates the maximum control current can be reduced to only 40% that of initial design by the optimizations. [ABSTRACT FROM AUTHOR]

In order to improve the working performance of linear metro, the multistep model predictive control (MMPC) is applied to linear induction machine (LIM) in this paper. However, due to the maximum current and voltage limitations, the optimal problem of multistep model predictive control (MMPC) becomes difficult to handle in practice. For simplifying the optimal problem of an MMPC with constraints, first, the optimal problem of MMPC is solved off-line, with the assumption that the input voltage of the LIM is continuous without limitations. And, the expression of current constraint is expressed by voltage variables through the mathematical model of the LIM to simultaneously consider both the voltage and current limitations. Then, according to the solved optimal value without constraints, one iterative algorithm is proposed to search a suboptimal value, which satisfies both the current and voltage limitations. Finally, the proposed strategy is applied to two 3-kW arc induction motors to verify its effectiveness. [ABSTRACT FROM AUTHOR]

While having various desired merits of high structural robustness and thus reliability, high thrust density, low fabrication cost, and so on, the stator-magnet moving-iron transverse-flux linear oscillatory machine suffers from high consumption of rare-earth magnetic material (high material cost) and heavy flux leakage at the stator outer region (underutilization of permanent magnets). To mitigate the demerits, a novel stator-magnet moving-iron transversal-flux hybrid-flux-path linear oscillatory machine (SMTHLOM), with additional back iron and auxiliary radially magnetized ferrite magnets, is proposed in this paper. The topology and operational principle of the proposed SMTHLOM are explained in detail. The 3-D finite-element analysis is introduced to investigate the sensitivities of main structural parameters, which enables the selection of optimal dimensions. Based on a set of comparison rules, a comprehensive comparison was conducted between these two topologies on various key indicators, such as the back electromotive force, thrust, and thermal distribution. The simulation results show that the SMTHLOM is low cost and small stator outer flux leakage, and thus is more suitable for some applications, e.g., fridge compressors, requiring low cost and high thrust density. [ABSTRACT FROM AUTHOR]

In this paper, one novel heteropolar radial hybrid magnetic bearing (HRHMB) is proposed for flywheel energy storage system. First, its structure and working principle are introduced in detail. Then, its fundamental equations are derived based on magnetic circuit model, such as displacement stiffness, current stiffness, and load capacity. Furthermore, its suspension performance and magnetic coupling are analyzed based on the 2-D finite-element analysis. Finally, the comparison of main performance indexes between the proposed HRHMB and conventional one under the same constraints is made. It indicates that the displacement stiffness can be reduced by the novel structure. In addition, the rotor core loss of the novel HRHMB is just 22.53 W, which is only 41.6% of the conventional eight-pole HRHMB with the same load capacity. [ABSTRACT FROM AUTHOR]

The pulsed high-power supplies in this paper employs a homopolar inductor alternator (HIA) as the motor/generator integrated energy storage pulsed alternator. Lumped parameter design equations are developed, which is used to establish the mathematical model of the HIA, and the analytic calculation method of inductance matrix is derived. Prototype flywheel energy storage was built, and the basic structure of HIA is analyzed by using finite-element method (FEM). This paper proposes a simplified equivalent 2-D salient-pole synchronous generator model to simplify the 3-D FEM of HIA and investigates the motor control method of HIA based on the simplified 2-D equivalent model. The experiments were conducted for speed up to 8000 rpm and the six-step inverter drive strategy presented in this paper achieves the motor/generator integrated control on inductor energy storage pulsed alternator (IESPA). Most experimental results were in line with designed value. [ABSTRACT FROM PUBLISHER]

Pulsed alternators have the merits of high energy and power densities, which are applied to a wide range of applications, such as the electromagnetic launch, the pulsed laser, and the pulsed high magnetic field. A new type of high-speed and high-frequency pulsed alternator integrating an alternator and a motor, is proposed in this paper. A solid rotor which is made of high-strength alloy steel with high yield strength is used in the pulsed alternator, so it can work at a high tip speed. This machine consists of two alternators and a motor which share one rotor and one field winding. According to different voltage levels and operation frequencies, the motor and the alternators with different stack lengths and pole-pairs are designed, respectively. Therefore, it has the abilities of being driven by low-frequency current and discharging high-frequency pulses. In this paper, the basic structure and fundamental of the pulsed alternator are introduced, the specific parameters of the prototype are given, and the performances are verified by the simulation. The results show that the machine proposed in this paper is suitable for the applications that require high-frequency pulsed discharge. [ABSTRACT FROM PUBLISHER]

Homopolar inductor alternator (HIA) has been widely used as a high-speed pulsed alternator in the electromagnetic launch field due to its merits of high-speed operation, power density, and reliability. To achieve the above-mentioned merits, a high-strength and high-stiffness solid rotor is usually adopted in the HIA. However, the solid rotor would be subject to high eddy current loss. Some works have been done to analyze the rotor eddy current of the HIA, while the research on analytic calculation and reduction of rotor eddy current loss is relatively few. In this paper, an analytic calculation method is established to calculate no-load rotor eddy current loss for HIA, which is validated by the finite-element analysis and corresponding experiments. Besides, to minimize the rotor eddy current loss, a simple method, by slitting the rotor tooth, is proposed. Moreover, the influence of circumferential and axial slits on the rotor eddy current loss and air friction loss is comparatively studied. Finally, the influence of the width, depth, and number of slits on the eddy current loss is investigated. It is shown that the circumferential slits have better performance than that of axial slits to reduce the eddy current loss. [ABSTRACT FROM PUBLISHER]

The deadbeat control (DBC) can track current reference closely, depending on the model of a linear induction machine (LIM). However, the DBC has to consider both the voltage and current constraints for staying in the safe working region of LIM, when calculating the input voltage vector of LIM. To solve such a challenge, one improved DBC with an iterative algorithm is proposed in this paper to solve the voltage and current constraints problem in the traditional DBC. Finally, the improved DBC is applied to 3 kW arc induction motors to verify its effectiveness. [ABSTRACT FROM AUTHOR]

One novel 4/6 stator/rotor single-phase doubly salient permanent magnet machine with asymmetric stator poles is proposed in this paper. The stator poles of proposed machine are distributed non-uniformly along the circumference of the stator yoke. First, it investigates the new topology and working principle in detail. Then, the presented structure is optimized based on 2-D finite element analysis. Finally, full comparison of electromagnetic performance indexes of the new machine with those of the traditional one is also presented. It indicates that the novel structure has a much higher torque density, lower cost of permanent magnet, and a much better starting capability than those of the traditional one under the constant volume and electrical load. [ABSTRACT FROM AUTHOR]

Persistent DNA damage is considered as a main cause of cellular senescence induced by ionizing radiation. However, the molecular bases of the DNA damage and their contribution to cellular senescence are not completely clear. In this study, we found that both heavy ions and X-rays induced senescence in human uveal melanoma 92–1 cells. By measuring senescence associated-β-galactosidase and cell proliferation, we identified that heavy ions were more effective at inducing senescence than X-rays. We observed less efficient repair when DNA damage was induced by heavy ions compared with X-rays and most of the irreparable damage was complex of single strand breaks and double strand breaks, while DNA damage induced by X-rays was mostly repaired in 24 hours and the remained damage was preferentially associated with telomeric DNA. Our results suggest that DNA damage induced by heavy ion is often complex and difficult to repair, thus presents as persistent DNA damage and pushes the cell into senescence. In contrast, persistent DNA damage induced by X-rays is preferentially associated with telomeric DNA and the telomere-favored persistent DNA damage contributes to X-rays induced cellular senescence. These findings provide new insight into the understanding of high relative biological effectiveness of heavy ions relevant to cancer therapy and space radiation research. [ABSTRACT FROM AUTHOR]

An air-core pulsed alternator is extremely attractive for driving the electromagnetic launchers. The reason is that the machine can offer high voltage and current performance in a single-element energy storage device, a smooth pulse profile, and naturally cycled current zeros, which can allow for extremely low muzzle currents and simplifies switching requirements. But because of the short history of the air-core pulsed alternator in China, the relevant theoretical research is not enough and the experience in fabrication is absent. It is really necessary to summarize a preliminary design method in order to rapidly determine the size and approximately evaluate the electrical performance of the machine. The optimization will be based on this first-stage design scheme. In this paper, based on the requirements of the railgun, some important design considerations of a seven-phase and six-pole air-core pulsed alternator are presented in detail. In addition, it is significant to obtain the analytical formulas for the first-stage design requiring less costs; these formulas intuitively allow us to expedite the design process and optimize the design scheme. Finally, some basic output parameters of the machine are given for the preliminary design; the designed pulsed alternator will generate 1.4 kV and drive a train of 1-MA pulses into a 5-m railgun, accelerating 200-g masses at 2 km/s. [ABSTRACT FROM PUBLISHER]

The high power pulsed charging power supply is usually necessary for the pulsed power devices with high power repetitive discharge. This paper first introduces a new topology structure of a charge and discharge system for high voltage capacitor and its operating principle, then comes up with technical requirements for the pulsed alternator. Afterward, design features of the inductor pulsed alternator, including the structure, main dimensions, and sizes of rotor teeth and slots are studied, and the main parameters of homopolar inductor pulsed alternator (HIPA) prototype are provided. The choice of rotor material and bearing failure phenomenon are also investigated to find a responsible solution. Finally, the experimental waveforms of HIPA prototype without and rated load when charging capacitor are given. The research shows that the pulsed power supply based on the inductor pulsed alternator is competitive for its high energy storage density, moderate power density, and high reliability, which is suited to the charging power supply of pulsed capacitor. [ABSTRACT FROM AUTHOR]

This paper presents an unexpected fluctuation of voltage for a 30-kW wound rotor brushless doubly-fed machine (BDFM) in a standalone power generation system. To address this issue, an improved method of harmonic injection is introduced. A voltage and current double closed-loop control strategy, based on control winding (CW) current decoupling, is applied through the entire experiment. Consequently, the experimental outcomes are fairly aligned with the dynamic simulations in most conditions. However, the voltage fluctuation in the power winding (PW) can be observed for a certain speed range. Harmonic analysis is then carried out on experimental data of PW voltage and CW current. A pair of interharmonic waves, which are symmetric with respect to the fundamental wave, is demonstrated to exist in PW voltage and CW current. Due to the analysis, these harmonic conjugate waves are caused by the high-order magnetomotive force tooth harmonics and current harmonics within a specific speed range. Accordingly, the control strategy of harmonic injection is employed to effectively eliminate these harmonic conjugate waves. The experimental results further highlight that the voltage amplitude can be maintained with less harmonic contents by our tailored control scheme. In addition, the formation and presence of harmonic conjugate waves may lead to the voltage amplitude fluctuation of BDFM in the standalone power generation system. [ABSTRACT FROM AUTHOR]

The air-core pulsed alternator has been studied for more than three decades. However, its optimized design theories are still rarely reported. The performance of the air-core pulsed alternator-based pulsed-power system is often closely associated with the electrical machine parameters, the system structure, and the load requirements. The parametric optimization of this type of alternator has a very important influence on the performance. This paper focuses on the optimization theory of the air-core pulsed alternator design, including the optimization of the magnetic field distribution, the turn number of armature winding, and the turn number of field winding. The features of the magnetic field distribution in the air-core pulsed alternators are analyzed based on the analytical expressions. By designing a ferromagnetic shield put on the outside of the stator, the radial magnetic field component increases and the circumferential one decreases. The optimization principles of the winding turn numbers are also deduced based on the system circuit and operation mode. The optimization theories are verified by system-level dynamic simulation. Finally, some rules are summarized, which are beneficial to the optimized design of the air-core pulsed alternator. [ABSTRACT FROM PUBLISHER]

As a novel pulsed-power supply, the air-core pulsed alternator is outstanding in providing repetitive pulse with high energy density, and preferred in a variety of fields including laser and electromagnetic launch, etc. To achieve a superior field excitation power supply, the air-core pulsed alternator usually adopts a self-excitation module, putting some emphasis on the design of the excitation conditions. In previous studies, the commutation voltage drop is neglected in excitation condition analysis. However, the voltage drop may have some significant impacts on the excitation conditions, and the neglect would cause a deviation between analysis and practices. This paper focuses on the analysis of excitation condition, taking the commutation voltage drop into account. [ABSTRACT FROM PUBLISHER]

In pulsed-power supply for electromagnetic launchers, air-core pulsed alternators have obvious advantages to enhance the power and energy densities. Compared with conventional machines, self-excitation mode is usually adopted due to the requirement of the large excitation current to establish the high flux densities in the air-core magnetic circuits. In this paper, a detailed description of the transient process involved with the air-core pulsed alternator operating at self-excitation mode is presented. First, it is necessary to supply a seed current rapidly prompting the alternator into the self-excitation mode. The capacitance and precharged voltage of the capacitor in excitation initialization module, which determine the seed current, are analyzed, and reasonable value ranges of the capacitance and the voltage are obtained. Then, when the machine is in self-excitation mode, a detailed study about the current and the voltage of the windings is carried out. Some innovational concepts, such as the equivalent impedance of the excitation winding R\mathbf {feq} and the growth rate of the excitation current K\mathbf {fi} , are proposed to simplify the transient analysis. They play a significant role to guide the optimization of our systems. Finally, the analysis is verified through the comparison with the Saber simulation results. [ABSTRACT FROM PUBLISHER]

This paper presents a novel brushless doubly fed alternator (BDFA) based on the differential mode and conducts research on its applications in a pulse capacitor charge power supply (CCPS). Since there are no brushes, the brushless doubly-fed alternator is expected to have high reliability and long service life. The excitation winding of the BDFA that is placed in the stator slots can be supplied with either dc or ac. In previous studies, regardless of the rotor configuration, the natural speed of BDFA is 60f/(p1+ p2) , i.e., based on the additive mode. To increase the alternator’s natural speed, expand the alternator’s operation as well as control range and to promote the alternator’s power density, this paper presents the differential mode, i.e., natural speed is equal to 60f/\vert p1-p2\vert . The author will introduce the detailed design method of the BDFA based on the differential mode. Utilizing the finite-element model of the alternator, we will analyze the magnetic field distribution and calculate inductance parameters of the BDFA. Subsequently, the inductance mathematic model of the BDFA will be established. We also establish the simulation model of the pulse CCPS. Finally, we will verify the feasibility of the design scheme for the BDFA through the simulation results in a pulse CCPS system. [ABSTRACT FROM PUBLISHER]

Background. Carbon ion therapy may be better against cancer than the effects of a photon beam. To investigate a biological advantage of carbon ion beam over X-rays, the radioresistant cell line HeLa cells were used. Radiationinduced changes in the biological processes were investigated post-irradiation at 1 h by a clinically relevant radiation dose (2 Gy X-ray and 2 Gy carbon beam). The differential expression proteins were collected for analysing biological effects. Materials and methods. The radioresistant cell line Hela cells were used. In our study, the stable isotope labelling with amino acids (SILAC) method coupled with 2D-LC-LTQ Orbitrap mass spectrometry was applied to identity and quantify the differentially expressed proteins after irradiation. The Western blotting experiment was used to validate the data. Results. A total of 123 and 155 significantly changed proteins were evaluated with treatment of 2 Gy carbon and X-rays after radiation 1 h, respectively. These deregulated proteins were found to be mainly involved in several kinds of metabolism processes through Gene Ontology (GO) enrichment analysis. The two groups perform different response to different types of irradiation. Conclusions. The radioresistance of the cancer cells treated with 2 Gy X-rays irradiation may be largely due to glycolysis enhancement, while the greater killing effect of 2 Gy carbon may be due to unchanged glycolysis and decreased amino acid metabolism. [ABSTRACT FROM AUTHOR]

Air-core pulsed alternators greatly enhance the power density capabilities of pulsed power supply for electromagnetic launchers. Compared with iron-core electric machines, they require very high-excitation currents. Usually, the self-excitation mode is adopted in these systems. However, the self-excitation mode is a positive feedback process that should be precisely controlled to avoid the system being destroyed. The excitation losses are very large during the process of establishing the large field current. To solve these problems, a new excitation mode, the pulse-excitation mode, is presented in this paper. The main idea is that a pulsed current charges the field coil so that the field coil and the armature coil conduct only for a short time around the main discharge pulse. This will avoid the machine being overheated and the risk of positive feedback process. Compared with the self-excitation mode, the pulsed alternator can be operated in a higher discharge frequency and the circuit schematic of the system is simpler. A larger field capacitor is used that charges the field coil to the desired current just by a pulse. As the energy density of pulse capacitor is enhanced rapidly, the volume and mass of the field capacitor are acceptable. The pulse-excitation mode is a combination of pulsed alternator and pulsed capacitor. In this paper, the characteristics of self-excitation and pulse-excitation are analyzed, respectively. The performances of both systems are simulated, and the main waveforms are presented. Finally, there is a practical comparison between them. [ABSTRACT FROM PUBLISHER]

The investigation of inductance mathematic model of a homopolar inductor alternator (HIA) in a novel pulse-capacitor charge power supply (CCPS) is presented. We study the characteristics of the inductance parameters based on the HIA theory and 3-D finite element analysis, establish the inductance mathematics model of HIA, and build a novel pulse-CCPS with 12/10-pole HIA. We also establish the simulation model of the power supply and compare the simulation results with the experimental one. The results prove the correctness of the inductance mathematic model. Finally, the problem of parameters-matching between the charging circuit and the HIA inductance is discussed. [ABSTRACT FROM PUBLISHER]