 کلمات کلیدی اتاق کنترل محاسبه ثابت صدا

 محاسبه ثابت اتاق در کنترل صدا masoomi دبیر انجمن       ارسال‌ها: 3,938 موضوع‌ها: 3,765 تاریخ عضویت: Aug 2012 اعتبار: 76 رشته تحصیلی: مهندسی بهداشت حرفه ای 07-20-2020، 11:55 AM (آخرین تغییر در ارسال: 07-20-2020، 12:40 PM توسط masoomi.) Now the last parameter R, the room constant, is very important and is defined as (R = A / (1- αm (R = Sαm / (1- αm :where (A = total room sound absorption (m2 Sabine αm = average absorption coefficient (S = total surface area (m2  room constant and sound pressure level (Lp = Lw + 10 log (Q / (4 π r^2) + 4 / R :where (Lp = received sound pressure level (dB (LW = sound power level from source (dB D = directivity coefficient (typical 1 for receivers in the middle of the room (R = room constant (m2 Sabin π = 3.14 (r = distance from source (m Example - Received Sound The sound power generated from a machine is 90 dB. The machine is located in a room with total sound aborption 12.2 m2 Sabine and mean absorption coefficient 0.2 The room constant can be calculated as R = (12.2 m2) / (1 - 0.2)  = 15.3 m2 Sabine For a receiver located in the middle of the room with a directivity coefficient 1 and distance 2 m from the source - the received sound pressure level can calculated as Lp = (90 dB) + 10 log (1 / (4 π (2 m)2) + 4 / (15.3 m2 Sabine) = 84.8 dB ثابت اتاق R، بسیار مهم است و به صورت زیر تعریف می‌شود (R = A / (1- αm (R = Sαm/ (1- αm A = جذب صدای کل اتاق (متر مربع Sabine) αm = متوسط ضریب جذب  S = مساحت کل (متر مربع) رابطه تراز فشار صوت با ثابت اتاق  (Lp = Lw + 10 log (Q / (4 π r^2) + 4 / R αm = ضریب جذب متوسط S = مساحت کل (متر مربع) Lp =  تراز فشار صوتی دریافت شده (dB) LٌW = تراز توان صدا از منبع (dB) Q = ضریب هدایت (1 عادی برای گیرندهها در وسط اتاق) R = ثابت اتاق (متر مربع سابین) r = فاصله از منبع (m) مثال - دریافت کننده صدا توان صوتی حاصل از یک ماشین 90 دسی بل است. دستگاه در اتاقی با كاهش صدا در کل 12.2 مترمربع سابین و متوسط ضریب جذب 0.2 قرار دارد. ثابت اتاق را می تواند به صورت زیر محاسبه شود مترمربع سابین 15.3= (R = A / (1- αm)=  R = (12.2 m2) / (1 - 0.2  برای گیرنده واقع در وسط اتاق با ضریب هدایت 1 و فاصله 2 متر از منبع - میزان فشار صوتی دریافتی می تواند به صورت زیر محاسبه شود Lp = (90 dB) + 10 log (1 / (4 π (2 m)^2) + 4 / (15.3 m^2 Sabine) = 84.8 dB Example A typical machine tool manufacturing area is 100 × 100 × 20 ft and has a room constant R of approximately 2000. From Fig. 9.4, the noise level due to the reverberant field at 5 ft from the machine is at most 2 dB above the free-field level. At 10 ft, the sound level of the reverberant field is about 4 dB above the free-field level, and at 20 ft the difference is nearly 10 dB Consider now the effect of increasing the room constant to 5000, i.e. , adding absorption. Note that at 5 ft there is no difference between the free field and the reverberant field; at 10 ft the noise level is only 2 dB above the free field, and at 20 ft the level is only about 4 dB above the free field. If, however, the room constant were increased to 10,000 (5 times the original absorption), noise level reductions of 6 to 8 dB could be obtained for distances beyond 10 ft Some conclusions can now be drawn Significant noise reduction can be obtained in manufacturing, assembly, or production areas by adding absorbing materials. However, little reduction is usually achieved within 10 ft of the source, which often includes a machine operator  In many factory areas, the noise sources or machines are distributed over the whole floor area. As such, moving 10 ft from a machine merely puts one into the near field of another with little or no noise reduction achieved  In summary, reverberation control in closely packed machine environments is usually only a secondary noise reduction measure. However, in areas remote to a noisy source, say 20 ft or more, the addition of absorptive treatment may reduce the reverberant noise buildup by 10 dB or more. Often these remote areas will contain a cluster of personnel such as inspectors, clerks, etc. , who will benefit significantly منابع مورد استفاده:Lewis H. Bell, Industrial Noise Control.2nd ed.new york:marcel dekke;1994

 موضوعات مشابه ... موضوع نویسنده پاسخ بازدید آخرین ارسال کنترل صدا و مثال های از کنترل صدا masoomi 0 473 04-13-2019، 12:12 AM آخرین ارسال: masoomi کنترل مدیریتی و کنترل مهندسی یا فنی صدای محیط کار masoomi 0 643 07-18-2018، 01:44 PM آخرین ارسال: masoomi

پرش به انجمن:

 کاربران در حال بازدید این موضوع: 1 مهمان 