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托福听力练习-科学美国人60秒:高频声波使超声图像清晰

2017-02-20 17:33:00来源：科学美国人60秒

点击查看>>科学美国人60秒音频：高频声波使超声图像清晰

　　科学美国人60秒中英文翻译：高频声波使超声图像清晰

　　科学美国人60秒英文文本

　　I'll never forget the day I saw the first ultrasound image of my peanut-size son-to-be.

　　If only the pictures weren't so fuzzy.

　　Is it a boy or—is that her foot?

　　Now physicists at Nanjing University in China have come up with a method to clean up pictures made from high-pitched acoustic waves.

　　Think of a one-way mirror—but for sound.

　　Their system would let the pressure waves that carry sound pass through if they come from the left.

　　But it reflects waves hitting it from the right.

　　No known natural material can do this.

　　But a metamaterial—a clever arrangement of thin brass plates bent into tiny maze-like shapes—has just the right properties.

　　The metamaterial can even be tailored to steer the outgoing sound and to filter out all sounds except those of a particular frequency.

　　That's just what you want for a sharp ultrasound picture.

　　The work appears in Applied Physics Letters.

　　The researchers are now building a prototype of their design.

　　Maybe one day, the only thing fuzzy about those first fetal photos will be the way they make you feel inside.

　　中文翻译请点击下一页

本文关键字: 托福听力练习 科学美国人60秒

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