Appendix C
Symbols

Table C.1 Greek Symbols I

αsAbsorption coefficient
βx,βy,βzPositive rotation around x, y, and z-axis
ΔωAngular frequency bandwidth
ΔTSampling interval
αDecay rate
αxStrain damping coefficient
δ()Dirac delta function
δBCCorrection factor for certain boundary condition
ζCritical damping ratio
ηDamping loss factor
ηm,ηmmDamping loss factor of mth system
ηmnCoupling loss factor of system m to n
ϑAzimuthal angle
κ=cv/cpSpecific heat ratio
λWavelength, first Lamé coefficient
μFrequency ratio, ratio factor
νPoisson ratio
ρDensity
ρfgCorrelation between f and g
ϕPhase angle
φPolar angle
ΦVelocity potential (chapter 2)
ΦnNormalized mode shape
ΨnMode shape
ΨL/SAmplitude of plate longitudinal and shear wave
ΨB1/2Amplitude of evanescent and propagating plate bending waves
ΠPower
ΠinInput power
ΠijTransmitted power from subsystem i to j

Table C.2 Greek Symbols II

σStress
σradRadiation efficiency
σSurface porosity
τDecay rate
τmnTransmission coefficient
ϕWave incident angle
ζ=cv/cvcRatio of viscous to critical viscous damping
ωAngular frequency
ω0Angular resonance frequency of undamped harmonic oscillator
ωdAngular resonance frequency of damped harmonic oscillator
ωdAngular frequency of maximum amplitude of damped harmonic oscillator
ωnModal angular frequency of mode n
ωs=2π/ΔtAngular sampling frequency

Table C.3 Capital latin Symbols I

ASurface, area
AcCross section of beam or tube
AComplex amplitude
BPlate bending stiffness
By,BzBeam bending stiffness for y and x-axis
[C]Viscous damping matrix
[D]Dynamic stiffness matrix
EEnergy, Young’s modulus
EkinKinetic energy
EpotPotential energy
FForce
F(ω),G(ω)Functions in frequency domain
FComplex force amplitude
GShear modulus
H(ω)Frequency response function
He=kLHelmholtz number
[I]Unit matrix
JTorsional moment of rigidity
IiiArea inertial moment
KBulk modulus
[K]Stiffness matrix
LLength
LjLength of junction
LpPressure level
LvVelocity level
LjJunction length
[L]Nonsymmetric power SEA matrix
[L]Symmetric SEA matrix
MMass (total)
MMoment vector
MxMoment in x-direction
[M]Mass matrix
NMode count
Nx/yForce per length in plates
PPerimeter
QQuality factor
QVolume source strength
Qx/yShear stress per length in plates
RRadius
RReflection factor
Rfg(t1,t2)Cross correlation function
SffPower spectral density
SSurface, section area
SjSurface of junction
SfgCross spectral density
TTime interval
TTransmission factor
TmemMembrane tension
TLTransmission loss
VVolume
W(ω)Spectrum of window function
YMobility
Z=F/VMechanical impedance
Za=psurf/QsurfRadiation impedance

Table C.4 Small latin Symbols I

an,bn,cnFourier coefficients
cWave speed
c0Wave speed in fluids
cgrWave group speed
cϕWave phase speed
cvViscous damping
cLLongitudinal wave speed in solids
cLBLongitudinal wave speed in beams
cLPLongitudinal wave speed in plates
cSShear wave speed
cvc=4mksCritical viscous damping
cveqEquivalent viscous damping
d={u,v,w}TDisplacement vector
eEnergy density
eEuler constant
fFrequency
fcCritical frequency
fqGeneral source term of acoustic wave equation
f(t),g(t)Functions in time domain
jImaginary number
hThickness of a plate
kWavenumber
kComplex wavenumber
ksSpring stiffness
n(ω)Modal density
mMass
mMass per unit length
mMass per unit area
mnModal mass
pAcoustic pressure
qGeneralised displacement
qsVolume source strength density
rsReflection coefficient
tTime
u,v,wDisplacement in x, y, and z-direction
vx,vy,vzVelocity in x, y, and z-direction
urDisplacement at resonance
vx0Initial velocity in x-direction
vxComplex velocity amplitude in x-direction
w(t)Window function in signal analysis
z0Characteristic acoustic impedance
z=p/vAcoustical impedance
za=psurf/vsurfAcoustic radiation impedance

Table C.5 Other Symbols

ImZImaginary part of Z
ReZReal part of Z
Infinity
Average operator
TAverage over time operator
EEnsemble average operator
VAverage over volume operator
SAverage over area operator
LAverage over length operator
E[]Expected value
F{ }Fourier transform
F1{}Inverse Fourier transform
^Real valued amplitude
{}Column vector (of coefficients)
rVector, geometrical
[]Matrix
()Denoted quantity per length
()Denoted quantity per area
x˙Time derivative
x¨Double time derivative

Table C.6 Indexes

i,jIndex for degrees of freedom
iIndex for inner degrees of freedom
sIndex for surface degrees of freedom
jXYIndex for junction degrees of freedom connected to system X and Y
m,nIndex for systems
(m)Index for system when subindex used by, e.g. other degrees of freedom
−1Inverse of a matrix
TTranspose of a vector
HHermitian of a matrix or vector
−HHermitian of the inverse of a matrix
ffCross correlation of force degrees of freedom
uuCross correlation of general displacement degrees of freedom
inDenoting input into a system
outDenoting output leaving a system
refDenoting reference values
reflDenoting reflection
transCross correlation of force degrees of freedom
Index denoting quantities of infinite or semi infinite systems
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