同时，为了进一步了解黑洞的物理过程，通过研究黑洞态以及其光变曲线的周期性变化一直以来是一种十分重要的方法。
Moreover, it is a very important method with study black hole states and the periodicity of the light curve to study their physical process.
第二部分研究了在氩气作保护气体的情况下，用变极性TIG焊方法焊钢时，焊接电流、电压的变化情况和电弧形态的变化。
The second is, when steel is welded by means of VPTIG of argon, the changes in current, voltage and arc shape.
第三部分研究了在氦气作保护气体的情况下，用变极性TIG焊方法焊铝时，焊接电流、电弧电压的变化情况和电弧形态的变化。
The third is, when Al is welded by means of VPTIG method of helium, the changes in current, voltage and arc shape.
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