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{
"metadata": {
"name": "",
"signature": "sha256:4126f9237f2a14d1c68d93136eb798698a28e20e098ed4ce42f02e377a8fbabb"
},
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"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"5: Acoustics"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.1, Page number 97"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"T1=1.5; #R time for empty hall(s)\n",
"T2=1; #R time with curtain cloth(s)\n",
"A=20; #area of absorber(sq.m)\n",
"V=10*8*6; #volume of hall(cu.m)\n",
"\n",
"#Calculation\n",
"a=((0.161*V)/(2*A))*((1/T2)-(1/T1)); #absorption coefficient\n",
"\n",
"#Result\n",
"print \"absorption coefficient is\",round(a,2),\"Sabines\"\n",
"print \"answer given in the book varies due to rounding off errors\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"absorption coefficient is 0.64 Sabines\n",
"answer given in the book varies due to rounding off errors\n"
]
}
],
"prompt_number": 4
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.2, Page number 97"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"V=20*15*10; #volume of hall(cu.m)\n",
"T1=3.5; #reverberation time(s)\n",
"l=20; \n",
"b=15;\n",
"h=10; #dimensions of hall\n",
"am=0.5; #absorption coefficient\n",
"T2=2.5; #reverberation time after cloth use(s)\n",
"\n",
"\n",
"#Calculation\n",
"A=(0.161*V)/T1; \n",
"S=2*((l*b)+(b*h)+(h*l)); #surface area(sq.m)\n",
"sigma_a=A/S; #average absorption coefficient of hall(o.w.u)\n",
"S1=(((0.161*V)/(am-sigma_a))*((1/T2)-(1/T1))); #area of wall covered by curtain cloth(sq.m)\n",
"\n",
"#Result\n",
"print \"average absorption coefficient of hall is\",round(sigma_a,3),\"o.w.u\"\n",
"print \"area of wall covered by curtain cloth is\",round(S1,3),\"sq.m\"\n",
"print \"answer for area covered S1 varies due to rounding off errors\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"average absorption coefficient of hall is 0.106 o.w.u\n",
"area of wall covered by curtain cloth is 140.156 sq.m\n",
"answer for area covered S1 varies due to rounding off errors\n"
]
}
],
"prompt_number": 8
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 5.3, Page number 98"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"V=1450; #volume of hall(cu.m)\n",
"A1=112*0.03; #absorption due to plastered wall\n",
"A2=130*0.06; #absorption due to wooden floor\n",
"A3=170*0.04; #absorption due to plastered ceiling\n",
"A4=20*0.06; #absorption due to wooden door\n",
"A5=100*1; #absorption due to cushioned chairs\n",
"\n",
"#Calculation\n",
"sigma_as=A1+A2+A3+A4+A5; #total absorption in empty hall\n",
"T1=(0.161*V)/sigma_as; #reverberation time case-1(s)\n",
"T2=(0.161*V)/(sigma_as+(60*4.7)); #persons=60,A=4.7 case-2\n",
"T3=(0.161*V)/(sigma_as+(100*4.7)); #seat cushioned=100 case-3\n",
"\n",
"#Result\n",
"print \"reverberation time for case-1 is\",round(T1,3),\"sec\"\n",
"print \"reverberation time for case-2 is\",round(T2,3),\"sec\"\n",
"print \"reverberation time for case-3 is\",round(T3,3),\"sec\"\n",
"print \"answer for T3 given in the book is wrong\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"reverberation time for case-1 is 1.959 sec\n",
"reverberation time for case-2 is 0.582 sec\n",
"reverberation time for case-3 is 0.396 sec\n",
"answer for T3 given in the book is wrong\n"
]
}
],
"prompt_number": 12
}
],
"metadata": {}
}
]
}
|
