The new safety guidelines were received positively by the factory staff.

received 是动词 receive 的过去分词形式，在句中表示被动语态。receive 的意思是"接收、接受"，这里指"被接受"。 positively 是形容词 positive 的副词形式，positive 意思是"积极的、正面的"，positively 表示"积极地、正面地"。 received positively 表示"被积极接受"。