periodical variation的用法和樣例：
例句
- Variations in the properties of the weld occurring at short regular intervals along the weld line due to repetitive variation in welding heat.
由於焊接熱量周期變化，使得沿焊縫線每一固定的小間距焊縫的性能出現周期性變化。 - Parametric rolling is a kind of the resonance phenomena of ship motions, caused by the periodical fluctuations of stability parameters of ships in waves.
參數橫搖是指船舶在波浪中由於自身系統中穩性參數的周期性變化所引起的船體梁橫搖共振運動現象。
