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采用标度变换法对陇中地区1368—1948年(明代至新中国建立前)各等级干旱灾害及旱季序列的时间分维值进行测算。并深入讨论了各旱灾序列时间分维与其线性特征之间的关系,以及分维随时间演进的变化趋势。对4个干旱等级、4个旱季序列的分维值进行研究,发现:①干旱灾害具有客观的分形结构,其时间序列是具有自组织性质的,干旱灾害是自组织系统;②各等级干旱灾害有自己的时间重演律,干旱灾害越轻,无标度区越宽,分维值越高,短周期更明显;③各旱季分维值与其发生频次成正比;④整个时期的动态总体上表现为:各旱灾序列(旱灾、大旱灾、中度干旱、春旱及伏旱)分维值逐渐增大,旱灾发生趋向混沌无序,旱灾系统趋向平衡态,稳定性减小;⑤分形分析法与常规统计方法之间有着内在联系。
Scale analysis was used to estimate the fractal values of the time series of drought disaster and drought season in Longzhong region from 1368 to 1948 (before Ming Dynasty to the founding of New China). The relationship between the fractal dimension of each drought sequence and its linear features and the trend of the fractal dimension evolution with time are discussed in depth. The fractal values of four drought gradients and four dry season sequences are studied. It is found that: ①Drought disasters have an objective fractal structure, the time series is self-organizing, and the drought disasters are self-organizing systems. Have their own time to recapitulate the law, the lighter the drought disaster, the wider the scale-free zone, the higher the fractal dimension value, the shorter the cycle is more obvious; (3) the fractal dimension value of every dry season is proportional to the frequency of occurrence; (4) the dynamic of the whole period The fractal dimension values of all drought series (drought, severe drought, moderate drought, spring drought and drought) gradually increase, the drought tends to chaos and disorder, and the drought system tends to the equilibrium state with less stability; ⑤ The fractal analysis There is an inherent relationship between conventional statistical methods.