Numerical study of alpha particle loss with toroidal field ripple based on CFETR steady-state scenario

Effects of plasma equilibrium parameters on the alpha particle loss with the toroidal field ripple based on the CFETR steady-state scenario have been numerically investigated by the orbit-following code GYCAVA. It is found that alpha particle losses decrease and loss regions become narrower with the plasma current increasing or with the magnetic field decreasing. It is because the ripple stochastic transport and the ripple well loss of alpha particle are reduced with the safety factor decreasing. Decrease of the plasma density and temperature can reduce alpha particle losses due to enhancement of the slowing-down effect. The direction of the toroidal magnetic field can significantly affect heat loads induced by lost alpha particle. The vertical asymmetry of heat loads induced by the clockwise and counter-clockwise toroidal magnetic fields are due to the fact that the ripple distribution is asymmetric about the mid-plane, which can be explained by the typical orbits of alpha particle. The maximal heat load of alpha particle for the clockwise toroidal magnetic field is much smaller than that for the counter-clockwise one.

Ripple区块链技术在国际贸易支付中的应用分析

Ripple区块链技术在现代社会的发展进程中,有着非常强大的去中心化系统,而这项系统的合理运用也极大程度上改善了我国现阶段面临的比较严重的国际结算信任以及工作效率问题。文章通过对Ripple区块链技术的详细阐述,更进一步增强了对国际贸易支付的有效管理与应用。基于此,文章从我国跨境支付的市场模式、区块链的金融交易运作原理、Ripple区块链在国际贸易中面临的挑战、Ripple区块链在国际贸易支付中的应用分析等层面开展更为详细的研究与分析。

Nonlinear mixing-based terahertz emission in inclined rippled density plasmas

We propose to investigate the THz field generation using nonlinear mixing mechanism of laser beat wave with inclined rippled density plasmas.Two laser pulses with frequencies(ω_(1),ω_(2)) and wave vectors(k_(1),k_(2)) co-propagate and resultant laser beat wave forms at beat frequency(ω_(1)-ω_(2)).Laser beat wave imparts a nonlinear force on the ambient electrons and pushes them outward with nonlinear velocity v_(NL).Coupling of induced density perturbation and nonlinear velocity v_(NL)generates nonlinear currents at laser beat frequency that further generates electromagnetic field E_((ω_(1)-ω_(2))) in terahertz(THz)range.In the present scheme,density ripples are introduced at an angle with respect to laser propagation and flat Gaussian index(f) is introduced in laser field profile that transform curved top of Gaussian field envelope into flat top field envelope.The combined effect of flat laser pulses with inclined density ripples in plasmas shows 10-fold enhancement in THz field amplitude when flat-Gaussian index(f) varies from 1 to 4.Also,the THz field intensifies when density ripples inclination increases upto a certain angle and then decreases.

Reduction of Unipolar Leakage Flux and Torque Ripple in Consequent-pole PM Vernier Machine

This paper proposes a new consequent-pole permanent magnet vernier machine(CPMVM),which can be regarded as a combination of two conventional CPMVM with opposite polarities.Based on the simplified axial magnetic circuit model,it is verified that the proposed CPMVM can reduce the unipolar leakage flux.In order to reduce the torque ripple of machine and improve the output torque of machine,the flux barrier is placed on the rotor of the proposed machine.Then,the parameters of the proposed CPMVM are optimized and determined.Moreover,the electromagnetic performance,including no-load air-gap flux density,average torque and torque ripple,flux linkage,back-electromotive force,cogging torque,average torque,torque ripple,power factor and loss,is compared with conventional surface-mounted permanent magnet vernier machine(SPMVM)and CPMVM.Finally,it is demonstrated that proposed CPMVM with flux barrier can effectively reduce the unipolar leakage flux and greatly reduce the torque ripple of machine.Also,compared with the SPMVM,the proposed CPMVM with flux barrier saves more than 45%of the permanent magnet material without reducing output torque.

Integrated Sliding Mode Velocity Control of Linear Permanent Magnet Synchronous Motor with Thrust Ripple Compensation

In this paper,a compound sliding mode velocity control scheme with a new exponential reaching law(NERL)with thrust ripple observation strategy is proposed to obtain a high performance velocity loop of the linear permanent magnet synchronous motor(LPMSM)control system.A sliding mode velocity controller based on NERL is firstly discussed to restrain chattering of the conventional exponential reaching law(CERL).Furthermore,the unavoidable thrust ripple caused by the special structure of linear motor will bring about velocity fluctuation and reduced control performance.Thus,a thrust ripple compensation strategy on the basis of extend Kalman filter(EKF)theory is proposed.The estimated thrust ripple will be introduced into the sliding mode velocity controller to optimize the control accuracy and robustness.The effectiveness of the proposal is validated with experimental results.

Design of Digital Linear Power Supply with Low Current Ripple

A linear power supply is a circuit architecture directly driven by AC. Multiple high-voltage LEDs (light-emitting diodes) are connected in series to withstand the input voltage. The LEDs are divided into multiple segments through a segment switching mechanism to adapt to the pulsating DC changes after bridge rectification. Due to imperfect switching between control signals, there may be signal overlap or misalignment, which reduces circuit performance and component lifespan. Firstly, signal overlap occurs when the next segment opens before the previous segment is about to close. This state causes overlapping intervals where two segments of current combine, resulting in a high combined current that can lead to significant power losses and generate heat, potentially reducing the lifespan of the components. Secondly, signal misalignment occurs when the next segment prepares to open after the previous segment has completely closed. In this state, there is a time gap with no current flow, resulting in reduced output power and exacerbating LED flickering. Both of these undesirable phenomena introduce ripple into the LED output current. In this paper, a digitalized design is proposed to precisely compensate for the timing between alternating signals, significantly reducing output current ripple. This approach helps enhance power supply performance, extend component lifespan, and reduce LED index flicker.

Analysis and simulation of the tune ripple effect on beam spill ripple in RF-KO slow extraction

Tune ripple has a significant influence on beam spill ripple in RF-knockout(RF-KO)slow extraction.In this study,a model was proposed to explain how the tune ripple affects the beam spill in RF-KO slow extraction;consequently,a simulation was performed using the lattice of the Xi’an Proton Application Facility(XiPAF)synchrotron to verify the model.The simulation demonstrates that the tune ripple influences the beam spill in two ways.On the one hand,the tune ripple causes a direct fluctuation in the separatrix area,which induces beam spill ripple.On the other hand,the tune ripple influences the emittance growth rate in RF-knockout slow extraction.These two aspects simultaneously contribute to the beam spill ripple.

互联网金融中的RIPPLE:原理、模式与挑战

RIPPLE是互联网金融在国际支付领域的一种新模式,是一种为在全球范围内进行转账和支付而设计的关于金融交易的互联网协议。RIPPLE表现出明显的去中心化、平台化特征,在国际支付中具有实时性、近乎零成本、覆盖范围更广等优势,因此可能对现在主流的SWIFT体系构成冲击。当然,RIPPLE协议要在未来成为主流的国际支付和清算方式,还面临着诸多困难,其中存在的安全风险也不容忽视,与之相适应的监管措施需要及早建立。

卡尔曼滤波器在海马场电位ripple节律分析中的应用

利用自适应自回归(adaptive autoregressive,AAR)模型和卡尔曼滤波器算法,分析小鼠海马CA1区场电位ripple高频振荡的时频特性.研究发现,与传统的基于短时傅立叶变换的实时频谱分析方法相比,利用AAR模型以及卡尔曼滤波器算法的参数化方法在对ripple高频振荡信号进行实时频谱分析时,具有更高的时域和频域分辨率.因此,基于卡尔曼滤波器得到的ripple能量变化,可更为准确、实时地反映ripple高频振荡的发生与变化过程.

Ripple与SWIFT比较分析研究

近年来,随着互联网技术的发展,Ripple1作为一种去中心化的支付清算系统,凭借其诸多优势逐步在国内外支付市场推广应用,并对以SWIFT为代表的国际主流支付系统产生影响。目前,我国的金融机构主要通过SWIFT实施跨境支付清算,但Ripple已开始在中国拓展业务。建议加强对Ripple的运行机制、商业模式等问题的研究,规范其在国内的应用。

从Ripple看区块链技术对跨境支付模式的变革与创新

以Ripple为代表的区块链跨境支付能降低现有支付清算模式下高昂的时间成本和资金成本,对我国金融机构的跨境支付带来了巨大的机遇和挑战。本文在比较分析我国现有的跨境支付的主要模式和Ripple基于区块链技术的跨境支付模式基础上,指出了区块链跨境支付的优势和创新效应,并对我国的区块链跨境支付的变革与创新提出了相应的建议。

基于Ripple的区块链技术在支付领域的应用

区块链技术是通过去中心化和去信任的方式,由集体共同维护一个可靠数据库的技术,众多知名机构均认为区块链技术有望革新现有的支付体系。本文介绍了区块链技术及其特征,并结合Ripple网络技术,探讨了区块链技术在支付领域的应用及其发展所遇到的问题。

Ripple机制构架、运作模式及监管思考

Ripple网络是世界上第一个"去中心化"的开放式支付清算网络,实现了资金点对点之间的转移,颠覆了传统中心交易对手的支付清算模式。本文对Ripple的内在机制构架、市场运作模式、潜在的风险点进行了研究,并在此基础之上,提出了相关政策监管建议。

基于Ripple共识机制的分布式作战资源分配方法研究

为确保分布式联合作战指挥条件下,战场空间、电磁频谱等作战资源在各作战行动间分配的一致性,避免产生作战资源运用上的冲突矛盾,基于区块链技术架构中的Ripple共识机制提出分布式作战资源分配方法。提出区分末端节点、协商节点和审核节点等3类功能节点的作战资源分配作业架构,设计“汇总作战资源使用申请、表决作战资源分配提案、调节作战资源使用冲突、确认作战资源分配结果”等4步作战资源分配流程。案例分析表明,在任意一对协商节点的UNL重复率大于或等于41%,且确认阈值不低于各节点UNL节点数量0.8倍时,能够确保各指挥节点协商得到一致性的作战资源分配结果。

THE LOSS OF STABILITY OF LAMINAR FLOW IN OPEN CHANNEL AND THE MECHANISM OF SAND RIPPLE FORMATION

In the flow on a mobile bed in an open channel, sand ripple often appears after the sediment begins to move. Different scholars have different views on the formation of sand ripples. This paper holds that as the ripple in general is very small, its formation is due to the instability of the laminar flow or the evolution of the small-scale coherent structures in the sublayer adjacent to the wall of the open channel. When the shear stresses caused by the disturbing waves or the coherent structure near the bed surface boundary and the water flow itself are greater than the shields stresses, responses on the bed surface appear and the sand ripple forms. If the frequency of the shear stress caused by the disturbance is close to the natural frequency of the sand grains that produced resonance, such a phenomenon is called the "detection property" of the sediment. It is at this point that the maximum resonance appears and the sand ripple develops rapidly.

Torque Ripple Suppression Control Strategy for Brushless Integrated Starter/Generator Wound-Field Synchronous Motor

A flux linkage compensation field oriented control (FOC) method was proposed to suppress the speed and torque ripples of a brushless wound-field synchronous motor in its starting process. The starting process was analyzed and the model of wound-field synchronous electric machine was established. The change of field current of the electric machine was described mathematically for simplified exciter and rotate rectifier. Based on the traditional field control, the flux linkage compensation was introduced in d-axis current to counteract the flux ripple. Some simulation and preliminary experiments were implemented. The results show that the proposed method is feasible and effective.

A Stator Current Vector Orientation Based Multi-objective Integrative Suppressions of Flexible Load Vibration and Torque Ripple for PMSM Considering Electrical Loss

To store energy from the grid into spiral torsion spring(STS)smoothly and efficiently via PMSM,a multi-objective control problem of flexible load’s vibration,PMSM’s torque ripple,and electrical loss is raised,where the current studies on vibration and torque ripple are mostly addressed separately,not to mention electrical loss.This research attempts to propose a multi-objective integrative control scenario that can simultaneously solve these problems satisfactorily in a unitary nonlinear control framework.Firstly,a dynamic mathematical model of PMSM is built under stator current vector orientation,and then the model of PMSM is combined with the vibration model of STS to establish the overall system model of STS driven by PMSM with considering motor’s electrical loss.Then,a backstepping control principle-based multi-objective integrative control approach is proposed to realize the suppression of flexible load’s vibration and the reduction of PMSM’s torque ripple and electrical loss concurrently.Meanwhile,this research also designs a wide range speed identification method based on the least square algorithm with a forgetting factor.Simulation and experimental results have verified that the proposed integrative control method enables the state variables to track their respective references quickly and accurately,both torque ripple and load vibration are effectively suppressed,and the operating efficiency of the whole system is improved.

Simulations of NBI fast ion loss in the presence of toroidal field ripple on EAST

NBI fast ion losses in the presence of the toroidal field ripple on EAST have been investigated by using the orbit code GYCAVA and the NBI code TGCO.The ripple effect was included in the upgraded version of the GYCAVA code.It is found that loss regions of NBI fast ions are mainly on the low field side near the edge in the presence of ripple.For co-current NBIs,the synergy effect of ripple and Coulomb collision on fast ion losses is dominant,and fast trapped ions located on the low field side are easily lost.The ripple well loss and the ripple stochastic loss of fast ions have been identified from the heat loads of co-current NBI fast ions.The ripple stochastic loss and the collisioninduced loss are much larger than the ripple well loss.Heat loads of lost fast ions are mainly localized on the right side of the radio frequency wave antennas from the inside view toward the first wall.For counter-current NBIs,the first orbit loss due to the magnetic drift is the dominant loss channel.In addition,fast ion loss fraction with ripple and collision for each NBI linearly increases with the effective charge number,which is related to the pitch angle scattering effect.

Research on Torque Ripple Under Healthy and Open-Circuit Fault-Tolerant Conditions in a PM Multiphase Machine

In this paper,research into torque ripple production has been undertaken for both the healthy and open-circuit faulttolerant conditions of a five-phase permanent magnet(PM)machine by using the instantaneous power(I-Power)approach.When only the fundamental component of the phase currents is applied to the phase windings,it has been shown that the 9th and 11th harmonics of the back-electromotive force(back-EMF)causes torque ripples in a five-phase PM machine and its frequency is ten times the frequency of the fundamental phase currents.When the combined fundamental and third harmonic components of the phase currents are applied to the phase windings,it has been shown that the 7th and 13th harmonic of the back-electromotive force(back-EMF)causes additional torque ripples in a five-phase PM machine.These torque ripples under fault-tolerant conditions have been analyzed analytically,as well.It has been proven that there are interactions between the fundamental component of current and the third harmonic component of the back-EMF and vice versa.These interactions cause torque ripples.A finite element analysis(FEA)model of the five-phase PM machine has been done to validate the analytical results.

Torque Ripple Reduction of Synchronous Reluctance Machine by Using Asymmetrical Barriers and Hybrid Magnetic Core

As there is no need of permanent magnet(PM)material and only silicon steel sheet required on the rotor,synchronous reluctance machine(SynRM)can be used for many applications and draws a great research interest.For the SynRM,the torque ripple is a big issue and a great of work could been done on reducing it.In this paper,asymmetrical magnetic flux barriers in the SynRM rotor were studied comprehensively,including angle and width of each layer and each side of the magnetic barrier.The SynRMb with asymmetrical and parallel magnetic flux barrier was found as the best way to design SynRM based on the multi-objective design optimization method.Moreover,each parameter was studied to show the design rule of the asymmetrical magnetic flux barrier.As the average torque will be reduced with the asymmetrical barrier is used,the grain-oriented silicon steel is used on stator teeth of the SynRMb(SynRMbG)was proposed and studied.The analysis results show that the proposed new method can make the SynRM have better performance.