We investigate the simultaneous observability of infinite systems of vibrating strings or beams having a common endpoint where the observation is taking place. Our results are new even for finite systems because we allow the vibrations to take place in independent directions. Our main tool is a vectorial generalization of some classical theorems of Ingham, Beurling and Kahane in nonharmonic analysis.

中文翻译：

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同时观察无限多个弦和梁

我们研究了具有共同端点的振动弦或梁的无限系统的同时可观测性。即使对于有限系统，我们的结果也是新的，因为我们允许振动沿独立方向发生。我们的主要工具是在非谐波分析中对英厄姆，贝林和卡汉的一些经典定理进行矢量归纳。