问题 问答题 简答题

刮大风或阴天下雨加热炉如何操作?

答案

参考答案:

如风小,对加热炉操作影响不大,但风大时,必须适当关小烟道挡板和风门,以免因风大形成抽力过大,使加热炉熄火,影响操作。

阴天下雨时,气压低,烟囱抽力受影响,必须适当开大烟道挡板,增加烟囱抽力,才能保证正常操作。

单项选择题

E

Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri (MU) researchers are developing a nuclear energy source that is smaller, lighter and more efficient.

"To provide enough power, we need certain methods with high energy density(密度)" ,said Jae Kwon, assistant professor of electrical and computer engineering at MU. "The radioisotope (放射性同位素) battery can provide power density that is much higher than chemical batteries. "

Kwon and his research team have been working on building a small nuclear battery, presently the size and thickness of a penny, intended to power various micro/nanoelectromechanical systems (M/NEMS). Although nuclear batteries can cause concerns, Kwon said they are safe.

"People hear the word ’ nuclear’ and think of something very dangerous," he said, "However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems. "

His new idea is not only in the battery’ s size, but also in its semiconductor(半导体). Kwon’ s battery uses a liquid semiconductor rather than a solid semiconductor.

"The key part of using a radioactive battery is that when you harvest the energy, part of the ra- diation energy can damage the lattice structure (晶体结构) of the solid semiconductor," Kwon said, "By using a liquid semiconductor, we believe we can minimize that problem. "

Together with J. David Robertson, chemistry professor and associate director of the MU Re- search Reactor, Kwon is working to build and test the battery. In the future, they hope to increase the battery’ s power, shrink its size and try with various other materials. Kwon said that battery could be thinner than the thickness of human hair.

According to Jae Kwon, his nuclear battery().

A. uses a solid semiconductor

B. will soon replace the present ones

C. could be extremely thin

D. has passed the final test

单项选择题 A3/A4型题