Being efficient to assist the aging or handicapped people when they live alone, the personal emergency response system ( PERS ) has owned more and more subscribers recently in western countries. 个人急救反应系统作为老年人、残疾人独立生活的辅助工具,近来在西方国家拥有越来越多的用户。
A Personal Instrument for Measuring Frequency Response Characteristics of an Audio System 一种测试音频系统频率特性的个人仪器