10 log 10 W W 10 L W = 10 log 10 W 10 12 10 log 10 I I 0 I 0 =10 12 I = P2 ρc = ρcv2
L p = 10 log 10 p 2 p 0 2 = 20 log 10 p p = 20 log p 10 0 2 10 5 L 3 = 10 log 10 10 L 1 /10 +10 L 2 ( /10 ) L 1 =10 log 10 10 L 3 /10 10 L 2 ( /10 )
10 L 1 /10 +10 L 2 /10 + 10 L 3 /10 +... +10 L n L =10 log /10 10 n E i = E r + E a + E t
α = E i E r E i = E a + E t E i τ = E t E i Ei Ea Et Er A = Sα α = A S = S i α i + A j S S i α i A j T = K V A = 0.16V Sα
1 TL =10 log 10 τ =10 log E i 10 E t TL 0 = 20 log 10 ( f m) 43 TL m = TL 0 10 log 10 ( 0.23 TL 0 )
L w = K w +10 log 10 Q + 20 log 10 P + C + BFI
cosθ R = 10 log S e + 1 α 2πd 2 αs w θ d d = ( 800 700) 2 + 650 2 + 400 2 = 770mm = 0.77m cosθ = 650 / d = 650 / 770 = 0.84 S e = 0.9 0.5 = 0.45m 2 S w = (1.1 0.7 2)+ (1.5 0.7 2) + (1.5 1.1 2) = 6.94m 2
α = {( S w S e S i ) 0.79 + ( S e + S i ) 1.0} S w { } 6.94 = 0.81 = ( 6.94 0.45 0.55 0.55) 0.79 + (0.45+ 0.55 0.55) 1.0 0.84 1 0.81 R = 10 log 10 0.45 2 + 2π 0.77 0.81 6.94 = 9.3dB L W = K +10 log 10 f + 50 log 10 U +10 log 10 S + 10 log 10 D 18 C = 1 BF = 1 C 1 BF = ( C 1) ( C 1) C 4 BF = C 1 ( ) ( ) C 1 C > 4 BF = 0.68 C 0.15 0.22 U = Q (S BF) St = f DU St < 25 K = 5 10.7 log 10 St St > 25 K = 40.2 35.9 log St 10 BF = ( 8 1) ( 8 1)= 0.26 U = (8000 3600) (0.5 0.5 0.26) = 34.2 St = 1000 0.5 34.2 = 14.6 K = 5 10.7 log 10 14.6 = 7.5
L w = 7.5 +10 log 10 1000 + 50 log 10 34.2 + 10 log 10 (0.5 0.5) +10 log 10 0.5 18 = 72dB L W = K +10 log 10 f + 50 log 10 U +10 log 10 S + 10 log 10 D + r + T 750 450mm (D M = 0.66m) Q = 8500CMH U M = 7.0m / s D = 4 S π 400 300mm (D M = 0.39m) Q = 2100CMH U B = 4.9m / s U M U B = 7.0 4.9 = 1.43 St = 1000 0.39 4.9 = 79.6 L w = 30 +10 log 10 1000 + 50 log 10 4.9 +10 log 10 0.12 +10 log 10 0.39 + 3 + 0 = 24.2dB
S Di K b = 10 log 10 S Di 10 log 10 Q b Q m K b S Di Q m Q b
L W 0 L W 0 R R E E L W L W L W = L W 0 R E R = L W0 L w E R E E E E ore > E E E R + E
L W =10 log 10 A + a log 10 V + b + c
Q L P = L W +10 log 10 + 4 4πr 2 R α S = 6.0 2.7 2 + 12.0 2.7 2 + 6.0 12.0 2 = 241.2m 2 R = 241.2 0.12 ( 1 0.12)= 32.9m 2 2 10 log 10 + 4 4 π 1.2 2 32.9 = 6.3dB
L P(all) = L P0 + X n Q i 4πr + 4 2 i =0 X = 10 log i R 10 Q 0 2 4πr + 4 0 R X L P0 L P(all) L P = L W TL D +10 log 10 4S A 1 A 2 TL C
4 L P = L W +10 log 10 A 4S L P = L W +10 log 10 TL A 1 A 2
L W 0 = L W +10 log 10 S A TL L P = L W 0 + 10 log 10 Q 4πd 2 L P = L W +10 log 10 S A TL +10 log 10 Q 4πd 2 L P = L W +10 log 10 4S A TL +10 log 10 Q 4πd 2
L P = L W 11 20 log 10 d +10 log 10 Q L P = L 8 + 10 log W (m 2 ) 10ψ
( ψ = π 2 ln A + 1 + A2 )B ( + 1+ B ) 2 A + B + 1+ A 2 + B 2 + kab L P = L +10 log ( ab) 11 20 log d +10 log Q W (m 2 ) 10 10 10
N 1.0 N = δ λ 2 R = 10 log 10 N +13 0.324 N <1.0 N < 0.324 8 R = 5 ± sinh 1 (1) sinh 1 ( N 0.485 ) R = 0