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变阶数有限差分法及逆时偏移有效边界存储最优化策略
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作者 宋利伟 石颖 +2 位作者 柯璇 张伟 孔祥琦 《地球物理学进展》 CSCD 北大核心 2017年第6期2527-2532,共6页
地震资料逆时偏移方法在计算过程中需要保存大量的波场信息,这种巨大的存储需求限制了该方法的实际应用.因此,研究能够显著降低波场存储量的存储策略对于推进逆时偏移方法的实用化具有重要的理论意义和实际价值.本文分别从时间和空间的... 地震资料逆时偏移方法在计算过程中需要保存大量的波场信息,这种巨大的存储需求限制了该方法的实际应用.因此,研究能够显著降低波场存储量的存储策略对于推进逆时偏移方法的实用化具有重要的理论意义和实际价值.本文分别从时间和空间的角度提出了相应的波场存储策略:(1)提出变阶数有限差分算子,在计算波场左、右和下边界处时,将差分阶数由高阶递减至二阶,结合有效边界存储策略,可在不损失波场重建精度的同时大幅降低波场存储量;(2)借鉴checkpoint策略和缓冲区思想,提出了基于拉格朗日乘子法的参数最优化方案,在时间方向上压缩波场存储量.通过对二维盐丘模型进行震源波场重建和逆时偏移存储量测试,结果表明:本文方法可实现对震源波场的高精度重建,与传统方法相比,在不损失成像精度的前提下,新的存储策略可大幅降低逆时偏移方法的波场存储需求. 展开更多
关键词 变阶数差分 逆时偏移 有效边界 存储策略 最优化策略
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A fractional-order multifunctional n-step honeycomb RLC circuit network 被引量:2
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作者 Ling ZHOU Zhi-zhong TAN Qing-hua ZHANG 《Frontiers of Information Technology & Electronic Engineering》 SCIE EI CSCD 2017年第8期1186-1196,共11页
We investigate a multifunctional n-step honeycomb network which has not been studied before. By adjusting the circuit parameters, such a network can be transformed into several different networks with a variety of fun... We investigate a multifunctional n-step honeycomb network which has not been studied before. By adjusting the circuit parameters, such a network can be transformed into several different networks with a variety of functions, such as a regular ladder network and a triangular network. We derive two new formulae for equivalent resistance in the resistor network and equivalent impedance in the LC network, which are in the fractional-order domain. First, we simplify the complex network into a simple equivalent model. Second, using Kirchhoff's laws, we establish a fractional difference equation. Third, we construct an equivalent transformation method to obtain a general solution for the nonlinear differential equation. In practical applications, several interesting special results are obtained. In particular, an n-step impedance LC network is discussed and many new char- acteristics of complex impedance have been found. 展开更多
关键词 Honeycomb network Equivalent transformation Fractional differential equation Impedance characteristics
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