Design of new resonant magnetic perturbation coils on the J-TEXT tokamak

The resonant magnetic perturbation(RMP) system is a powerful auxiliary system on tokamaks.On the J-TEXT tokamak, a set of new in-vessel coils is designed to enhance the amplitude of the RMP. The new coils are designed to be two-turn saddle coils. These two-turn saddle coils have been optimized in terms of their structure, support, and protection components to overcome the limitations of the narrow in-vessel space, resulting in a compact coil module that can be accommodated in the vessel. To veri...     

Investigation of the J-TEXT plasma events by k-means clustering algorithm

Various types of plasma events emerge in specific parameter ranges and exhibit similar characteristics in diagnostic signals,which can be applied to identify these events.A semisupervised machine learning algorithm,the k-means clustering algorithm,is utilized to investigate and identify plasma events in the J-TEXT plasma.This method can cluster diverse plasma events with homogeneous features,and then these events can be identified if given few manually labeled examples based on physical understa...     

The spectrum analysis of RMP coils with multiple connection modes and the design of high field side coils on J-TEXT

The phase difference Δξ between locked islands (2/1 and 3/1) has been found to influence the heat transport on the thermal quench during disruptions by numerical modeling [Hu Q et al 2019 Nucl. Fusion 59, 016005]. To verify this experimentally, a set of resonant magnetic perturbation (RMP) coils is required to excite coupled magnetic islands with different Δξ. The spectrum analysis shows that the current RMP coils on J-TEXT can only produce sufficient 2/1 and 3/1 RMP fields with a limited phase difference of Δξ∈[−75°, 75°]. In order to broaden the adjustable range of Δξ, a set of coils on the high field side (HFS) is proposed to generate 2/1 and 3/1 RMP fields with Δξ = 180°. As a result, RMPs with adjustable Δξ∈[−180°, 180°] and sufficient amplitudes could be achieved by applying the HFS coils and the low field side (LFS) coils. This work provides a feasible solution for flexible adjustment of the phase difference between m and m + 1 RMP, which might facilitate the study of major disruptions and their control.     

基于Newton迭代法的Julia集的生成方法

介绍了Newton迭代法的基本思想及其改进方法，研究了用于复多项式的Cayley问题，并且从理论上讨论了Newton迭代法在Julia集研究中的重要作用，给出了用Newton迭代代法和成Julia集的计算机快速算法。     

关于逆Walsh序的快速Walsh变换算法研究

从Walsh变换算法出发，总结出快速算法中的二分技术设计思路，提出了逆Walsh序的快速Walsh变换算法，给出了逆Walsh序的算法的流程图，为算法在图像处理中的实际应用打下基础。     

改进的多级树集合分裂(SPIHT)算法

基于中频和高频子带小波系数中的不重要数的相关性，对SPIHF算法提出一些改进．在改进SPIHT算法中，利用一个组合函数来减少相应位置中频子带的不重要小波系数的冗余．构造集合d来减少高频子带带间的冗余．实验结果表明，改进SPIHT算法相对于改进前SPIHT算法有理想的压缩效果，峰值信噪比和人眼视觉效果都有所提高．     

Walsh矩阵的复制生成及其计算机图像

Walsh函数在信号处理、图像处理、通信等众多领域有着广泛的应用.Walsh函数系是一个正交而完备的函数系,可以通过多种方法生成这一函数系.其中,Swick提出的复制方法应用最为广泛,该方法以Walsh函数的序码作为复制信息,可以复制出任意给定序数的Walsh函数.其本质是基于向量的处理,不适于类似快速变换等二维信号的处理.Walsh函数系可用Walsh方阵Wk表示.提出了基于W_k的行复制和块复制方法.基于对称性引入复制算子,并发现了一种新序(类Walsh序).利用Kronecker积推导了6种序的Walsh方阵的递推公式并绘制了它们的计算机图像,发现这些图像具有分形意义上的自相似结构.结果表明,基于矩阵的复制是比基于序码的复制更先进的复制方法.前者性能更优,适于快速变换的设计.而且,利用它发现了Walsh函数系的第4种对称的序:类Walsh序.通过分析和比较各种序的计算机图像,得出类Walsh序更适合作为Walsh序的逆反形式的猜想.     

基于神经网络与对比度的多聚焦图像融合技术

提出了一种基于小波对比度和神经网络的多聚焦图像融合算法。首先对各源图像进行小波变换，根据变换后系数计算出图像的小波对比度，选取源图像部分区域小波对比度作为前馈神经网络的训练样本，调整神经网络权重；然后用训练好的神经网络组合融合图像的小波系数，对组合后的系数进行一致性校验；最后对该系数进行小波逆变换，得到融合图像。实验结果表明，该算法能够较好地解决多聚焦图像融合问题，生成的融合图像效果优于传统图像融合方法。     

元胞自动机的演化行为研究*

基于元胞自动机演化行为研究与仿真系统,通过对元胞自动机的一、二、三维演化行为的研究,从统计和渐进的角度对元胞自动机进行了分类,将元胞自动机的演化行为动态统计图与沃尔弗拉姆对于元胞自动机的分类对应起来研究.这些从不同视角得到的结果有助于对元胞自动机的演化行为进行深入研究;但从统计和渐进的角度对元胞自动机进行分类是否具有普适性,是需要进一步研究探讨的问题.     

Peano曲线的演化生成算法及其推广

基于演化思想探讨了Peano空间填充曲线的非递归生成算法及其推广.通过基本元素的确定、变换和组合三个步骤完成曲线的绘制.算法简单、快速,而且有一定的通用性.