صفحه 1:
صدا و ارتعاش در صنعت
جلسه دوم
محمد رضا منظم
mmonazzam@hotmail.com
صفحه 2:
eo
مروري بر ریاضیات
صفحه 3:
2 Real Numbers
at(btd=(atD+c , 240-6
atb=b+a_ , ab=ba
db+d=abtac , اك bay
Ava sa
صفحه 4:
mt 1
ea
4 Indices
(at) تم a =a Faden =a aes
صفحه 5:
Logarithms
yo=x ee n=log, vy
log| xy} =log,x+log,y , log, 3 ب 7ر10 1 رومت
log, x"| =mdog, x
el _ log, x
log, x= 7 log, * Tog, n
log, n
صفحه 6:
53 The Binomial Theorem
(a+ D? =a? +2ab+ b
(a+ D® =a? + 3a’b+ 3ab +B
ey ad جات ویر "و +ج)
dn- ( 9 2
)1+ بر ج... + لیر جرور +1- "لر n>0
dn- 1(...)0- و(
2
(14+ 9” =1+ nx+...+ all n
صفحه 7:
2 Trigonometry
0 6010 - 0 , cosed = 2 ار 9008 1
cod tam sing
003
6)=-sin, co$- 6) =co#, tat 6) =- tam نزو
sir’ 9+cos @ =1
1+ tari م6 =secéa
cot @ +1=coseca
صفحه 8:
Trigonometry (continue..)
it A+B =sinAcosB+cosdsinB co$A+B =cosAcosBFsinAsinB
00 ا
1+tanAtanB
1 4 ۰ 2tanA
co@A=cos A- sit A sin2A=2sinAcos4 tarA=.
1- tart A
J 4 1 2
3 ۰ 78 = 3 ۳ X+ 23
SURE SIY بای sinx- SHY رت
cosx+ cosy=2cos=-* cos”, 005 005۲ - مور sinX ال
صفحه 9:
Radian Measure
360 =27 raa 240 =* rad
cos? =0, > @ =nt
ifsim) =sina= 0 وع +) ۵
if cos) =cosa> 0 =2m +a
iftam=tam = @=m+a
a x
x=sim) = 0=sin'x ع وت
2 2
x=cos = @ =cos'x 0-6 >>
xstaw = 0 =tan'x pee gre
2 2
صفحه 10:
Complex Numbers
¥64=8-8 y= 64=8/-1 1 04-9
fol pai از <1
اه رم لت لح سا ها موه ویو
Z=a+ jb
Oukexvuncd operatic ty موی او با نوا ec.
ie cone (a+ jBlc+ jd =(ac- bd + fad+ bd
22 نه لال اك +
at jb_(a+ jhlc- jd _ و
c+ jd (c+ jdlc- jd e+ ne + Abe ad
لك ا 0ك )2 2125 )
صفحه 11:
Modulus (magnitude) and Argument
و
+ 22
ol ی ره
@=arg=tan'2 - > *>7
صفحه 12:
4 Polar Form of a Complex Number
= The argument can be written:
6098 ay sind -> - ۲ > >
4 3
= Therefore
z=|Acos) + jsind)
ZZ, =|z\|z,| coo, +0,)+ jsio, +0,)|
A ا - 6) + jsila, - آ(یه
2 |Z
صفحه 13:
Polar Form of a Complex
2
Ce et ata
2!
cosx=1- = tea 13 oe we
a a! ۳
9
eel (red!
(cers Pore)
بت رح زو
OSB
R xbyjo in thee*
2 pf
تس ۳ -1|- ام
2 4
Boor AS
0- م 7
ا
=cos# + jsind
aa
صفحه 14:
Polar Form of a Complex Number
(continue)
= Zcan be written as:
ae 0
لور دج
مصزوز + ومع و
jsind -وووع و
مرج - 6
sing SOs eae
2
e+e”
cos? =
2
صفحه 15:
Fourier Analysis
(Joseph Fourier (1706-1790)
* Fourier series
It enables periodic functions to be represented by infinite
series of sine and cosine terms.
8 07م مع كر د
5 for a function
(Powter series Por te Rauctoa ضجا
fo gat dle cosit+ b, sinnot|
عا 2
an
a Dcosnwtdt اج رت
rs
2 فا
رك - sf sinmotdt
صفحه 16:
Fourier Analysis
(Joseph Fourier (1706-1790))
= Infinite Fourier Transform and inverse Fourier Transform
gsi] =Xo) = fle at
ecll 1 5 اس
é | X(a)] i dt
صفحه 17:
Fundamental concept
* Any moving form-some shape or pattern that travels along without
carrying all the medium with it.
Some type of wave:
Water wave
Wave on string- musical instrument
Mexican wave
Wind causing wave
Heat wave
Electromagnetic wave
Sound wave
صفحه 18:
Velocity, Frequency and wave length
ايا ومسي افا
i /۱ ۷ {\ re
5
a Hoque Hoe
i Te
nea
= The velocity of a wave (c):
the speed at which its
wave-form travels along,
the speed of any labelled
part of the disturbance.
" The frequency of a wave (f):
The number of oscillation it
makes in 1 second.
In 1 second the wave has
travelled "c” metres so that
"ع" metres contains “f”
cycles of the wave.
Hence in space one
complete wave is ¢/f metres
long (wavelength A)
The time of one oscillation
is the period (T)
c
a tod,
0 6
صفحه 19:
How Waves Travel
=" A wave travels essentially because:
= One piece of the medium disturbed by the wave
disturbs the next piece of medium ahead and
gives up the motion to it.
= The waves are:
= Longitudinal: The pieces of the medium oscillate in
the same direction as the wave propagate.
= Transverse: The pieces of the medium oscillate
perpendicular to the direction propagation of the
wave.
= Some other types including, Shear and Bending
صفحه 20:
Mathematical Description of
۳ Harmonic Wave
= The disturbance at x: at
time ti is due to the
disturbance at position xo
which occurred at time
to (% - x)
45 و
200080 وا - 0 < ود 01
صفحه 21:
4 Mathematical (continue)
= For harmonic waves ( plane wave):
انم بر Flot 0 2051117611132
S25 Axil 3 ct+ x) ۱ negativdirectic
20 xwures the wave repes every waveleonth
صفحه 22:
4 Mathematical (continue)
= Complete representation of a plane wave:
To allow the wave to have any value:
y= Axil (ct | + Boot (ct 3]
‘Pwe mt A=Dcosy) and — B=Dsirlg)
y=Dcoky) xsi (ct 5 + أده (ولشوط (ct a
, where D=V A’ +B andtap) =3
y=Dsif (ct ور +
صفحه 23:
۳ Mathematical (continue)
= Alternative equation for plane wave:
: ۶-9 and w=2f
ot- Fxeg فده دير
or
y=Cxsirlot- kx 9), k 00 (waveumber
صفحه 24:
۳ Mathematical (continue)
= Complex Representation
ae إلدع ار
یزرو A=A+jA
or
y=(4.+ JA) co} 2 (ct x + joi "Ect 01 and the real par.
ya Aco} 2 (op | Asi 2 (ct- a|
صفحه 25:
Examples (1)
= If the displacement of the particles of the
medium is described by:
0-0005 207 +
= What is the amplitude, frequency ,wavelength
and wave number and what is the speed of the
wave?
صفحه 26:
+ Examples (2)
= The pressure fluctuations in air are described
by:
p=0.01co$20G@t- 1.85x) + 0.005sir 20Gt- 59
= What is the amplitude, frequency, wavelength
and the speed of the wave.
صفحه 27:
4 Examples (3)
= The pressure, p, is described by:
p= +مالويم kt
= |f the pressure amplitude is 0.01 pa and at t=0
, X=0 the value of p is 0.005 pa find Ar and Ai.
صفحه 28:
{oe
Thanks for Listening
صدا و ارتعاش در صنعت
جلسه دوم
محمد رضا منظم
mmonazzam@hotmail.com
مروري بر رياضيات
Real Numbers
a b c a b c ,
a b b a
ab c ab ac
,
,
abc abc
abba
b c b c
a
a a
a 0
Indices
a a
m n
m
n
mn
, a n am
a 1
0
,
am m n
,
a
n
a
, am.an amn
a
n
1
a
n
Logarithms
n
y x
logn xy logn x logn y
n logx y
,
x
logn logn x logn y
y
logn xm mlogn x
1
logn x
logx n
,
logm x
logn x
logm n
,
The Binomial Theorem
a b
2
a b
3
2
2
a 2ab b
3
2
2
3
a 3a b 3ab b
nn 1...n r 1 n r r
a b a na b ...
a b .... bn
r!
n
1 x
n
n
1 nx
n 1
nn 1
2!
2
x
nn 1n 2
3!
x3 .... xn
nn 1....n r 1 r
1 x 1 nx ...
x ....
r!
n
n 0
all
n
Trigonometry
sin
1
tan
, cot
,
cos
tan
sin sin ,
1
cosec
,
sin
cos cos ,
tan tan
sin2 cos2 1
1 tan sec
2
2
cot2 1 cosec2
1
sec
cos
Trigonometry (continue..)
sinA B sinAcosB cosAsinB,
cosA B cosAcosB sinAsinB
AB tanAtanB
tan
1tanAtanB
cos2A cos2 A sin2 A,
sin2A 2sinAcosA,
2tanA
tan2A
1 tan2 A
x y x y
x y x y
sinx siny 2sin
cos
, sinx siny 2cos
sin
2
2
2
2
x y x y
x y x y
cosx cosy 2cos
cos
, cosx cosy 2sin
sin
2
2
2
2
Radian Measure
360 2 rad
0
4
240
rad
3
0
cos 0, n
if sin sina
n 1n a
if cos cosa
2n a
if tan tana
n a
x sin
sin 1 x
2
2
x cos
cos 1 x
0
x tan
tan 1 x
2
2
Complex Numbers
64 8, 8
j 2 1
64 8 1
j 3 j
64 8 j
j 4 1
complex number has both real and imaginary component
z a jb
Mathematical operation is similar to real number e.g.
a jb c jd a c jb d
Conjugate of
a jbc jd ac bd jad bc
z is z*
zz* a jba jb a2 b2
a jb a jbc jd
1
2 2 ac bd jbc ad
c jd c jdc jd c d
z1 z2
*
*
1
*
2
z z ,
z1z2
*
* *
1 2
z z ,
z z
n *
* n
Modulus (magnitude) and Argument
(angle)
z a jb a2 b2
z z,
zz z
*
*
b
argz tan
a
1
2
Polar Form of a Complex Number
The argument can be written:
cos
a
,
z
sin
b
z
Therefore
z z cos j sin
z1z2 z1 z2 cos1 2 j sin1 2
z1
z1
cos1 2 j sin1 2
z2
z2
Polar Form of a Complex
Number
r
x
ex 1 x
...
...
2!
r!
x2
2r
x
r
cosx 1
... 1
....
2r!
2! 4!
x2
x4
x2r1
sinx x
... 1
....
2r 1!
3!
5!
x3
Replacing
2
4
e j 1
2! 4!
x5
r
x by j in the ex
...
3 5
j
3! 5!
(Euler’s formula)
.. cos j sin
Polar Form of a Complex Number
(continue)
Z can be written as:
z ze
j
e j cos j sin
e j cos j sin
e j e
sin
2j
cos
j
e j e
2
j
Fourier Analysis
(Joseph Fourier (1706-1790))
*
Fourier series
It enables periodic functions to be represented by infinite
series of sine and cosine terms.
for a function f t f t nT
Fourier series for the function is:
1
f t a0 an cosnt bn sinnt
2
Tn1
a0
an
bn
2
T
2
T
2
T
f tdt
0
T
f tcosnt dt
0
T
f tsinnt dt
0
Fourier Analysis
(Joseph Fourier (1706-1790))
Infinite Fourier Transform and inverse Fourier Transform
jt
x t X x t e dt
1
1
X xt
2
jt
X
e
dt
Fundamental concept
Wave:
Any moving form-some shape or pattern that travels along without
carrying all the medium with it.
Some type of wave:
Water wave
Wave on string- musical instrument
Mexican wave
Wind causing wave
Heat wave
Electromagnetic wave
Sound wave
….
Velocity, Frequency and wave length
The velocity of a wave (c):
the speed at which its wave-form
travels along, the speed of any
labelled part of the disturbance.
The frequency of a wave (f):
The number of oscillation it makes in
1 second.
In 1 second the wave has travelled
“c” metres so that “c” metres
contains “f” cycles of the wave.
Hence in space one complete wave is
c/f metres long (wavelength λ)
The time of one oscillation is the
period (T)
c
,
f
c f ,
T
1
f
How Waves Travel
A wave travels essentially because:
One piece of the medium disturbed by the wave disturbs
the next piece of medium ahead and gives up the motion
to it.
The waves are :
Longitudinal: The pieces of the medium oscillate in the
same direction as the wave propagate.
Transverse: The pieces of the medium oscillate
perpendicular to the direction propagation of the wave.
Some other types including, Shear and Bending
Mathematical Description of
Harmonic Wave
The disturbance at x1 at
time t1 is due to the
disturbance at position x0
which occurred at time
t0.
t1 t0
x1 x0
c
ct1 x1 ct0 x0 constant
Mathematical (continue)
For harmonic waves ( plane wave):
2
ct x
y Asin
postivedirection
2
ct x
y Asin
2
negative
direction
ensures the wave repeats every wavelength
Mathematical (continue)
Complete representation of a plane wave:
To allow the wave to have any value:
2
2
y Asin ct x Bcos ct x
If we put:
A D cos
and
B D sin
2
ct x D sin cos 2 ct x
y D cos sin
2
ct x , where D A2 B2 and tan B
A
y D sin
Mathematical (continue)
Alternative equation for plane wave:
y C sin t
2
x ,
f c
and
or
y C sint kx ,
k
2
(wavenumber
)
2f
Mathematical (continue)
Complex Representation
2
ct x
j
j t kx
y Ae
y Ae
or
, or
A Ar jAi
2
ct x j sin 2 ct x
y Ar jAi cos
2
ct x Ai sin 2 ct x
y Ar cos
and the real part
Examples (1)
If the displacement of the particles of the
medium is described by:
d 0.005sin 20t x
2
What is the amplitude, frequency ,wavelength
and wave number and what is the speed of the
wave?
Examples (2)
The pressure fluctuations in air are described
by:
p 0.01cos200t 1.85x 0.005sin200t 1.85x
What is the amplitude, frequency, wavelength
and the speed of the wave.
Examples (3)
The pressure, p, is described by:
p Ae
j t kx
If the pressure amplitude is 0.01 pa and at t=0
, x=0 the value of p is 0.005 pa find Ar and Ai.
Thanks for Listening