The new models of artificial hearts are expected to be equipped with an external power source.

预计给人造心脏的新模型配备一个外部能源系统。

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It handles up to eight cameras and offers 24-vac or 28-vac selectable outputs to accommodate voltage drops without an external power source.

该装置可同时处理八个摄像机，提供24伏和28伏可选输出，无需外部电源就能适应电压下降。

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Using light as an external power source can alleviate the weight and mass of having an onboard system, leaving room for scientific payloads, for example, and it provides more propulsive power.

利用光束作为外部能量源可以减轻火箭自身携带的系统重量和质量，为科学研究扩大有效载荷空间，并提供更大的推力。

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The engineers found a way to kick-start a radio-frequency device wirelessly using an external power source initially, but running the device afterward on the output of power generated by the inner ear.

WSJ: Harnessing Energy From the Body to Power Devices

Or they can transport heat from an external source of power and manipulate it to cool a surface.

FORBES: The Trillion Mile-Per-Gallon Engine