江苏省四校2017届高三12月联考英语试卷_高中英语试卷

江苏省四校2017届高三12月联考英语试卷

　　Among the most basic forms of the technology is body power. When certain materials are squeezed or stretched, the movement of their atoms creates an electrical charge. Automatic watches have employed the concept for decades, for example, by winding themselves when their user moves their arm. Now, the concept is being considered for a number of other devices.

　　In a contest seeking visionary ideas for wearable technologies, Intel awarded $5,000 for a concept to change the temperature difference between a person’s body and a special piece of clothing they’d wear into electricity for mobile devices.

　　Using sound to power devices is another energy-harvesting variation. Stanford University engineers are testing smart microchips that create electricity from ultrasound to power implantable devices that can analyze a person’s nervous system or treat their diseases.

　　A textile research association in Spain is proposing to obtain electricity from radio waves that flow around everyone to power sensors sewn into clothes, which can monitor a person's heartbeat or other vital signs. Research firm lDTechEx has estimated that annual global sales of energy-harvesting products could hit $2.6 billion by 2024, while WinterGreen Research predicts sales of $4.2 billion by 2019.

　　Obtaining stable energy from devices can be complex, however. For one thing, the motion that generates the electricity has to be constant to be useful. Moreover, the amount of power the devices produce depends on the person using them，according to a Columbia University study. It determined that taller people on average provide about 20 percent more power than shorter ones when walking, running or cycling.