共查询到17条相似文献,搜索用时 125 毫秒
1.
2.
研究了一类二维变量描述的激发系统中漂移螺旋波的抑制问题.通过在整个系统中局部注入带随机相位的电信号,如在系统256×256格点的边界或中心区域中选取4×4或者5×5格点区域施加一个带随机相位的外部激励电信号,在系统内部产生一个持续的靶波信号,实现靶波对螺旋波的动态竞争.数值计算表明:该方法对于Barkley模型中螺旋波有很强的抑制作用,与简单的局部周期信号驱动比较,具有暂态过程比较短的特点,而且对于时空噪声具有一定的抗干扰性.在一定的噪声范围内,即使系统出现不均匀性,也可以观测到靶波,新出现的靶波对螺旋波有抑制作用.
关键词:
螺旋波
靶波
Barkley模型
随机相位 相似文献
3.
采用非连续反馈方法来控制Fitz-Hugh-Nagumo方程描述的激发介质中的螺旋波. 在控制过程中,对于系统各个格点快变量的幅值进行观测并和设定的阈值进行比较,当采样格点的快变量的值大于这个阈值时,则对系统进行直接小幅度的负反馈. 研究发现:在对系统所有格点快变量幅值观测时选择比较小的阈值则更容易将系统的螺旋波消除掉并使系统达到稳定均匀态. 在比较大的阈值下,系统的螺旋波则变得稀疏,也可以导致螺旋波的破裂. 在任意选择单个格点的快变量观测下,比较小的反馈强度仍然可以消除螺旋波,系统也达到稳定均匀态. 当
关键词:
螺旋波
Fitz-Hugh-Nagumo方程
反馈控制 相似文献
4.
5.
采用系统中的局部不均匀性消除振荡系统中的反螺旋波. 该不均匀性在系统中成为一个波源,不断产生稳定的相波. 研究结果发现,不均匀性的尺寸大小存在一个临界值,如果低于此临界值,则系统将无法激发任何相波. 根据不均匀性形状的不同,系统分别产生靶波和行波. 此外,实验还发现靶波与反螺旋波之间以及行波与反螺旋波之间存在着不同的动态竞争. 数值计算表明,对于行波,无论是低频行波还是高频行波,都可以成功地消除系统中的反螺旋波;而对于靶波,只有低频靶波才可以消除反螺旋波. 此控制方法简单易行,且同样适用于消除向外传播的螺旋波 相似文献
6.
在离散可激发介质Greenberg-Hasting模型中引入交替(alternans)行为,研究了交替行为对螺旋波的影响.数值结果表明:在适当选择参数下,交替对螺旋波有很大影响,例如交替导致螺旋波的形状振荡,形成呼吸螺旋波,交替使螺旋波漫游、漂移,甚至使螺旋波漫游出系统的边界,交替使螺旋波破碎形成小螺旋波、反靶波和时空混沌等,首次在均匀介质中观察到交替导致传导障碍,使螺旋波破碎和消失,并对发生这些现象的机理进行了分析.
关键词:
离散可激发介质
螺旋波
靶波
漫游 相似文献
7.
8.
9.
10.
11.
In this paper, an intermittent local electric shock scheme is proposed to
suppress stable spiral waves in the Barkley model by a weak electric shock
(about 0.4 to 0.7) imposed on a random selected n×n grids (n=1-5,
compared with the original 256×256 lattice) and monitored
synchronically the evolutions of the activator on the grids as the sampled
signal of the activator steps out a given threshold (i.e., the electric
shock works on the n×n grids if the activator
u\leq0.4 or u \geq 0.8). The numerical
simulations show that a breakup of spiral is observed in the media
state evolution to finally obtain homogeneous states if the electric
shock
with appropriate intensity is imposed. 相似文献
12.
Based on fractional Fourier transform, an image encryption algorithm is proposed and researched. A local random phase encoding is introduced into this algorithm. The data at the local area of complex function is converted by fractional Fourier transform. The local random phase encoding is performed many times. Moreover only one set of random phase data is used in image encryption process. Compare to double random phase encoding, the parameter defining local area can be regarded as the additional key to increase the security of the encryption scheme. Some numerical simulations are achieved to demonstrate the performance of the image encryption scheme. 相似文献
13.
In this paper, we develop an efficient splitting domain decomposition method (S-DDM) for compressible contamination fluid flows in porous media over multiple block-divided sub-domains by combining the non-overlapping domain decomposition, splitting, linearization and extrapolation techniques. The proposed S-DDM iterative approach divides the large domain into multiple block sub-domains. In each time interval, the S-DDM scheme is applied to solve the water head equation, in which an efficient local multilevel scheme is used for computing the values of water head on the interfaces of sub-domains, and the splitting implicit scheme is used for computing the interior values of water head in sub-domains; and the S-DDM scheme is then proposed to solve the concentration equation by combining the upstream volume technique. Numerical experiments are performed and analyzed to illustrate the efficiency of the S-DDM iterative approach for simulating compressible contamination fluid flows in porous media. The developed method takes the excellent attractive advantages of both the non-overlapping domain decomposition and the splitting technique, and reduces computational complexities, large memory requirements and long computational durations. 相似文献
14.
Nishaanthan Nadarajah Elaine Wong Ka Lun Lee Ampalavanapillai Nirmalathas 《Optics Communications》2007,273(1):246-251
A scheme for upstream transmission and local area network emulation in passive optical networks using a single reflective semiconductor optical amplifier placed at the customer premises is proposed and experimentally demonstrated. In this scheme, two optical carriers are delivered to the optical network units from the central office for the transmission of upstream and local area network signals, respectively. 相似文献
15.
大规模量子通信网络中,采用量子分组传输技术能有效提升发送节点的吞吐量,提高网络中链路的利用率,增强通信的抗干扰性能.然而量子分组的快速传输与路由器性能息息相关.路由器性能瓶颈将严重影响网络的可扩展性和链路的传输效率.本文提出一种量子通信网络分层结构,并根据量子密集编码和量子隐形传态理论,给出一种基于分层的量子分组信息传输方案,实现端到端的量子信息传输.该方案先将量子分组按照目的地址进行聚类,再按聚类后的地址进行传输.仿真结果表明,基于分层的量子分组信息传输方案能够有效减少量子分组信息在量子通信网络中的传输时间,并且所减少的时间与量子路由器性能与发送的量子分组数量有关.因此,本文提出的量子分组信息传输方案适用于大规模量子通信网络的构建. 相似文献
16.
In order to effectively improve the quality of side information in distributed video coding, we propose a side information generation scheme based on a coefficient matrix improvement model. The discrete cosine transform coefficient bands of the Wyner–Ziv frame at the encoder side are divided into entropy coding coefficient bands and distributed video coding coefficient bands, and then the coefficients of entropy coding coefficient bands are sampled, which are divided into sampled coefficients and unsampled coefficients. For sampled coefficients, an adaptive arithmetic encoder is used for lossless compression. For unsampled coefficients and the coefficients of distributed video coding coefficient bands, the low density parity check accumulate encoder is used to calculate the parity bits, which are stored in the buffer and transmitted in small amount upon decoder request. At the decoder side, the optical flow method is used to generate the initial side information, and the initial side information is improved according to the sampled coefficients by using the coefficient matrix improvement model. The experimental results demonstrate that the proposed side information generation scheme based on the coefficient matrix improvement model can effectively improve the quality of side information, and the quality of the generated side information is improved by about 0.2–0.4 dB, thereby improving the overall performance of the distributed video coding system. 相似文献
17.
MA Jun YI Ming ZHANG Li-Ping JIN Wu-Yin LI Yan-Long 《理论物理通讯》2008,49(6):1541-1546
In this paper, a new scheme of spatial perturbation is proposed to stabilize the pattern in the oscillatory media, which could be described with the complex Ginzburg-Landau equation. The numerical simulation results confirm that the spiral wave, antispiral wave and spatiotemporal chaos in the complex Ginzburg-Landau equation could be suppressed, and the scheme is also discussed with the conservative field theory. Furthermore, the spatiotemporal noise is also introduced into the whole media, it just confirms that it is robust to the spatiotemporal noise. 相似文献