简介:摘要电力在国民经济发展中占据非常重要的地位,用电的安全稳定影响着各行各业的发展,关系到人民群众的安居乐业。因此,企业在建设过程中一定要重视电力基础设备的安装工作,只有做好电力基础设备的安装工作,才能保证企业的正常运行,减少不必要的损失。笔者结合自己掌握的有关电力设备的安装知识,介绍了电力工程配电设备安装的相关内容,希望能够为电力设施的基础建设出一份力。
简介:Proceedingfromtheeigenvalueequationofthenormalmodeinhomogeneousshallowwater,wederiveseveralformulaecalculatingthemodeattenuationandgroupvelocity,andcomparetheiraccu-racybymeansofnumericalresults.Thepaperespeciallydiscussestheattenuationandthegroupve-locityofcriticalmodeinaPekerischannelandshowsthatingeneral,theattenuationandthegroupvelocityofthecriticalmoderespectivelyarelessthantheabsorptionandthesoundspeedinthebot-tom.Therefore.theKornhauser,Raney,WestonTindle‘sconclusionsaremodifiedthattheattenuationandthegroupvelocityofthecriticalmodeareexactlyequaltotheabsorptionandthesoundspeedinthebottom,respectively.
简介:BasedonthenoisesurveyinChina,theformula(H′=H+N-HN/120)ofISO/DIS1999.2("Acous-tics-DeterminationofOccupationalnoiseexposureandestimationofnoise-inducedhearingimpairment,1985)wasappliedtothecalculationofthehearingthresholdlevelassociatedwithageandnoise(HTLAN)ofthenoise-impairedpeople.AccordingtotheGaussciandistribution,whenthenoise-exposurelevelLEX8hwas85,90,95,100dBandthehearingthresholdfrequencyisfrom0.5kto6kHz,theHTLANofnoise-exposedpeoplewithdifferentdurationofexposureanditsrelationvaluestothehearingthresholdfrequencyassociatedwithage(HTLA)wereobtained.TheISO/DIS1999.2hasbeenprovedtobeapplicableinChina.