NF F48-220-1991 铁路固定设备.信号设备、通信设备和计算机设备用模块化电源.二次系统

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Product Code:SAE AIR1672
Title:Practical Methods to Obtain Free-Field Sound Pressure Levels From Acoustical Measurements Over Ground Surfaces
Issuing Committee:A-21 Aircraft Noise Measure Noise Aviation Emission Modeling
Scope: Acquisition of free-field data is of practical significance in the field of aeronautical acoustics. The need for free-field data includes (but is not restricted to) the following: comparison of acoustical data obtained from the same engine under various measurement conditions; comparison of the results obtained from models with those from an engine on a test stand; comparison of noise measurements made on the same engine under static and in-flight conditions; design of test facilities; standardization of techniques for 'in situ' acoustical measurements; spectral decomposition to isolate the contribution of different sources to the total noise; and prediction of aircraft noise on the basis of methods which, generally, provide free-field data. There is an increasing tendency to test full-scale engine components and scale models in anechoic test facilities that provide free-field conditions. This AIR complements this work by identifying those methods in current use which provide free-field acoustic data for measurements on engines under static conditions in the presence of a ground surface. Separate Appendices to this AIR describe different methods for noise measurement in the field that conform with the state-of-the-art to a certain extent. That is, each method has generally been systematically used by at least oe free-field conditions. This AIR complements this work by identifying those methods in current use which provide free-field acoustic data for measurements on engines under static conditions in the presence of a ground surface. Separate Appendices to this AIR describe different methods for noise measurement in the field that conform with the state-of-the-art to a certain extent. That is, each method has generally been systematically used by at least one organization and has been substantiated by data obtained from at least one test site.ne organization and has been substantiated by data obtained from at least one test site.【英文标准名称】:Opticalfibrecables-Part1-1:Genericspecification-General
【原文标准名称】:光纤电缆.第1-1部分:总规范.一般规范
【标准号】:IEC60794-1-1-1999
【标准状态】:作废
【国别】:国际
【发布日期】:1999-03
【实施或试行日期】:
【发布单位】:国际电工委员会(IEC)
【起草单位】:IEC/SC86A
【标准类型】:()
【标准水平】:()
【中文主题词】:
【英文主题词】:
【摘要】:
【中国标准分类号】:M33
【国际标准分类号】:33_180_10
【页数】:75P;A4
【正文语种】:英语