中文摘要：

介绍了一种全新的基于小波分析原理的处理非等间隔数据的方法：加权小波z变换（WeightedWaveletZ—transform，WWZ）．收集了类星体3C345光学B波段100多年来较为完整的观测数据，获得了其长期光变曲线．利用wwz变换对3C345B波段28yr的光变数据进行分析，通过研究发现3C345的光变曲线中包含有624~941d、4．54-5．23yr和9．59-11．51yr的周期成分，并分析了它们随时间演化的情况．其中后两个周期成分属于稳定周期，而前一个周期成分波动比较大，可以推测它并不是一个稳定周期．

英文摘要：

A new method to analyze unevenly spaced data is described, which is based on the principle of wavelet analysis called the Weighted Wavelet Z-transform （WWZ）. All available optical B-band data of quasar 3C 345 from more than 100 years are collected in this paper, and the long-term light curves of 3C 345 are presented. With the WWZ method, the data between the years of 1965 to 1992 are analyzed. The results show that there are 3 periodic components in the data. Based on our analysis, the periodicity of T=4.54~5.23 yr and T=9.59~11.51 yr is steady, while T=624-941 d is not a steady period.