a device for concentrating (= increasing the strength of) a substance by removing or reducing the amount of something such as water, or by collecting particular atoms or molecules together

She uses an oxygen concentrator to make it easier to breathe. 氧气浓缩器

a mirror or group of mirrors that focuses light from the sun (= directs its waves towards a particular point) so it can be used to produce power

The company will build at least 50 acres of solar concentrators behind the plant to generate solar power. 该公司将在工厂后面建造至少50英亩的太阳能聚光镜来发电。

a device in a computer or telephone network that collects and combines information or signals from separate sources

The primary concentrators process and store information, received from some 40 meters. 主集中器处理和存储从大约40米处接收到的信息。

Each node (PC) attaches to a hub (or concentrator) via a cable. 每个节点（个人电脑）通过电缆连接到一个集线器（或集中器）上。

at some universities, someone who is studying a particular subject as their main subject

At Harvard in the late 1950s, philosophy concentrators were few. 1950年代末，哈佛大学主修哲学专业的学生很少。

You need a year of math if you're going to be a biology concentrator. 要成为生物专业的学生，需要学习一年的数学。