Fast fading, Slow fading and Multipath effect in wireless communicationsPei-Che Chang
Fast fading, Slow fading and multipath effect in wireless communications
QPSK in AWGN channel
QPSK in AWGN + Rayleigh fading channel
using GNU Octave simulation
Fast fading, Slow fading and Multipath effect in wireless communicationsPei-Che Chang
Fast fading, Slow fading and multipath effect in wireless communications
QPSK in AWGN channel
QPSK in AWGN + Rayleigh fading channel
using GNU Octave simulation
SYNGAS PRODUCTION BY DRY REFORMING OF METHANE OVER CO-PRECIPITATED CATALYSTSIAEME Publication
The syngas manufacturing from the reforming of methane with carbon dioxide is tempting because of output in terms of extra pure synthesis gas and lower H2 to CO ratio than other synthesis gas production methods like either partial oxidation or steam reforming. For production of long-chain hydrocarbons though the Fischer-Tropsch synthesis, lower H2 to CO ratio is required and important, as it is a most likely feedstock. In recent decades, CO2 utilization has become more and more important in view of the emergent global warming phenomenon. On the environmental point of view, methane reforming is tantalizing due to the reduction of carbon dioxide and methane emissions as both are consider as dangerous greenhouse gases. Commercially, as cost effectively, nickel is used for methane reforming reactions due to its availability and lower cost compared to noble metals. Number of catalysts endures rigorous deactivation because of carbon deposition. Mainly carbon formation is because of methane decomposition and CO disproportionate. It is important and required to recognize essential steps of activation and conversion of CH4 and CO2 to design catalysts that minimize deactivation. Effect of promoters on activity and stability were studied in the detail. In order to develop the highly active with minimum coke formation the alkali metal oxides and ceria/zirconia/magnesia promoters were incorporated in the catalysts. The influence of ZrO2, CeO2 and MgO, in the performance of Ni-Al2O3 catalyst, prepare by co-precipitation method was studied in detailed. The XRD, FTIR, and BET and reactivity test for different promoted and unprompted catalyst was carried out.
Presented in Chinese, but basically about a design project. My subject is "Wintersweet and Snow", from an idea from Chinese ancient poem"梅须逊雪三分白,雪却输梅一段香" to design to factory production - the whole process, involves all we learn during undergrad period. (PS, CAD,Coreldraw...)
The document discusses wave-particle duality and electron diffraction. It begins by explaining wave-particle duality, stating that particles can behave as waves and vice versa. It then discusses the Davisson-Germer experiment, which demonstrated that electrons diffract like waves, confirming de Broglie's hypothesis. The document concludes by discussing electron microscopes, which use the wave properties of electrons to achieve higher resolutions than optical microscopes.
- The document discusses the photoelectric effect where ultraviolet (UV) light causes a zinc plate to emit electrons called photoelectrons.
- It describes several experiments where changing the intensity and frequency of the UV light impacts the number and kinetic energy of the emitted photoelectrons.
- Key concepts explained include the work function, which is the minimum energy needed to remove an electron from a metal, and how it differs for different metals. The threshold frequency is the minimum frequency needed to cause photoemission for a given metal.
The document discusses the photoelectric effect and Einstein's explanation of it using photon theory.
1) The photoelectric effect occurs when light shines on certain metals and generates an electric current. Classical physics could not explain observations that the current depends on frequency, not intensity, of light.
2) Einstein proposed that light consists of discrete packets of energy called photons. Photons can transfer their entire energy to eject electrons from a metal surface, but only if they have enough energy to overcome the metal's work function.
3) Einstein's explanation accounted for key observations, like the current dependence on frequency alone and a threshold frequency below which no current occurs regardless of intensity. It established light's particle-like properties and
High level introduction
Mainstream syngas = steam reforming processes
Ammonia; methanol; hydrogen/HyCO
Town gas
Steam reforming; low pressure cyclic
Direct reduction iron (DRI)
HYL type processes; Midrex type processes
SYNGAS PRODUCTION BY DRY REFORMING OF METHANE OVER CO-PRECIPITATED CATALYSTSIAEME Publication
The syngas manufacturing from the reforming of methane with carbon dioxide is tempting because of output in terms of extra pure synthesis gas and lower H2 to CO ratio than other synthesis gas production methods like either partial oxidation or steam reforming. For production of long-chain hydrocarbons though the Fischer-Tropsch synthesis, lower H2 to CO ratio is required and important, as it is a most likely feedstock. In recent decades, CO2 utilization has become more and more important in view of the emergent global warming phenomenon. On the environmental point of view, methane reforming is tantalizing due to the reduction of carbon dioxide and methane emissions as both are consider as dangerous greenhouse gases. Commercially, as cost effectively, nickel is used for methane reforming reactions due to its availability and lower cost compared to noble metals. Number of catalysts endures rigorous deactivation because of carbon deposition. Mainly carbon formation is because of methane decomposition and CO disproportionate. It is important and required to recognize essential steps of activation and conversion of CH4 and CO2 to design catalysts that minimize deactivation. Effect of promoters on activity and stability were studied in the detail. In order to develop the highly active with minimum coke formation the alkali metal oxides and ceria/zirconia/magnesia promoters were incorporated in the catalysts. The influence of ZrO2, CeO2 and MgO, in the performance of Ni-Al2O3 catalyst, prepare by co-precipitation method was studied in detailed. The XRD, FTIR, and BET and reactivity test for different promoted and unprompted catalyst was carried out.
Presented in Chinese, but basically about a design project. My subject is "Wintersweet and Snow", from an idea from Chinese ancient poem"梅须逊雪三分白,雪却输梅一段香" to design to factory production - the whole process, involves all we learn during undergrad period. (PS, CAD,Coreldraw...)
The document discusses wave-particle duality and electron diffraction. It begins by explaining wave-particle duality, stating that particles can behave as waves and vice versa. It then discusses the Davisson-Germer experiment, which demonstrated that electrons diffract like waves, confirming de Broglie's hypothesis. The document concludes by discussing electron microscopes, which use the wave properties of electrons to achieve higher resolutions than optical microscopes.
- The document discusses the photoelectric effect where ultraviolet (UV) light causes a zinc plate to emit electrons called photoelectrons.
- It describes several experiments where changing the intensity and frequency of the UV light impacts the number and kinetic energy of the emitted photoelectrons.
- Key concepts explained include the work function, which is the minimum energy needed to remove an electron from a metal, and how it differs for different metals. The threshold frequency is the minimum frequency needed to cause photoemission for a given metal.
The document discusses the photoelectric effect and Einstein's explanation of it using photon theory.
1) The photoelectric effect occurs when light shines on certain metals and generates an electric current. Classical physics could not explain observations that the current depends on frequency, not intensity, of light.
2) Einstein proposed that light consists of discrete packets of energy called photons. Photons can transfer their entire energy to eject electrons from a metal surface, but only if they have enough energy to overcome the metal's work function.
3) Einstein's explanation accounted for key observations, like the current dependence on frequency alone and a threshold frequency below which no current occurs regardless of intensity. It established light's particle-like properties and
High level introduction
Mainstream syngas = steam reforming processes
Ammonia; methanol; hydrogen/HyCO
Town gas
Steam reforming; low pressure cyclic
Direct reduction iron (DRI)
HYL type processes; Midrex type processes
This document discusses modeling of land ice sheets and their impact on climate. It summarizes different approaches that can be used to model ice sheet dynamics, including the shallow-ice approximation and shallow-shelf approximation, which make simplifying assumptions about stress and shear. It also discusses the importance of surface and basal mass balance, temperature dynamics, and friction in modeling ice sheets accurately. The key properties of ice sheets that are important to model are their mass and thickness over time.
20. .
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Ch2 数值计算
时间积分
One-stage method
Forward Euler Scheme (order=1)
算法
Xn+1
= Xn
+ dt · F(Xn
)
Fortran 95 Code
1 subroutine forward (x0 , x1 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0
6 real , dimension (N) , intent ( out ) : : x1
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xtend
9 c a l l tend (x0 , xtend ,N)
10 x1 = x0 + dt * xtend
11 end subroutine
21. .
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Ch2 数值计算
时间积分
One-stage method
Matsuno Scheme (order=1 or 1.5)
算法
Xest
= Xn
+ dt · F(Xn
)
Xn+1
= Xn
+ dt · F(Xest
)
Fortran 95 Code
1 subroutine matsuno(x0 , x1 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0
6 real , dimension (N) , intent ( out ) : : x1
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xest , xtend
9 c a l l tend (x0 , xtend ,N)
10 xest = x0 + dt * xtend
11 c a l l tend ( xest , xtend ,N)
12 x1 = x0 + dt * xtend
13 end subroutine
22. .
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Ch2 数值计算
时间积分
One-stage method
Heun Scheme (order=2)
算法
Xest
= Xn
+ dt · F(Xn
)
Xn+1
= Xn
+
1
2
dt ·
[
F(Xn
) + F(Xest
)
]
Fortran 95 Code
1 subroutine heun(x0 , x1 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0
6 real , dimension (N) , intent ( out ) : : x1
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xtend0 , xest xtendest
9 c a l l tend (x0 , xtend0 ,N)
10 xest = x0 + dt * xtend0
11 c a l l tend ( xest , xtendest ,N)
12 x1 = x0 + 0.5 * dt * ( xtend0 + xtendest )
13 end subroutine
26. .
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Ch2 数值计算
时间积分
One-stage method
以 Runge-Kutta (order=4) 为例
Fortran 95 Code
1 subroutine rk4 (x0 , x1 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0
6 real , dimension (N) , intent ( out ) : : x1
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xtend , q1 , q2 , q3 , q4
9
10 c a l l tend (x0 , xtend ,N)
11 q1 = dt * xtend
12
13 c a l l tend ( x0+0.5*q1 , xtend ,N)
14 q2 = dt * xtend
15
16 c a l l tend ( x0+0.5*q2 , xtend ,N)
17 q3 = dt * xtend
18
19 c a l l tend ( x0+q3 , xtend ,N)
20 q4 = dt * xtend
21
22 x1 = x0 + 1.0/6.0 * ( q1 + 2*q2 + 2*q3 + q4 )
23 end subroutine
28. .
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Ch2 数值计算
时间积分
Multi-stage method
Leapfrog Scheme (order=2)
蛙跃格式
算法
Xn+1
= Xn−1
+ 2dt · F(Xn
)
Fortran 95 Code
1 subroutine forward (x0 , x1 , x2 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0 , x1
6 real , dimension (N) , intent ( out ) : : x2
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xtend
9 c a l l tend (x1 , xtend ,N)
10 x2 = x0 + 2.0 * dt * xtend
11 end subroutine
29. .
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Ch2 数值计算
时间积分
Multi-stage method
ABM Predictor-Corrector Scheme (order=3)
算法
Xest
= Xn
+
1
2
dt ·
[
3F(Xn
) − F(Xn−1
)
]
Xn+1
= Xn
+
1
12
dt ·
[
5F(Xest
) + 8F(Xn
) − F(Xn−1
)
]
Fortran 95 Code
1 subroutine abm(x0 , x1 , x2 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0 , x1
6 real , dimension (N) , intent ( out ) : : x2
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xtend0 , xtend1 , xest xtendest
9 c a l l tend (x0 , xtend0 ,N)
10 c a l l tend (x1 , xtend1 ,N)
11 xest = x1 + 0.5 * dt * (3* xtend1−xtend0 )
12 c a l l tend ( xest , xtendest ,N)
13 x2 = x1 + 1.0/12.0 * dt * ( 5* xtendest + 8*xtend1 − xtend0 )
14 end subroutine
31. .
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Ch2 数值计算
时间积分
Multi-stage method
以 Adams-Bashforth (order=4) 为例
Fortran 95 Code
1 subroutine ab4(x0 , x1 , x2 , x3 , x4 ,N)
2 i m p l i c i t none
3 ! i n t e r f a c e
4 integer , intent ( in ) : : N
5 real , dimension (N) , intent ( in ) : : x0 , x1 , x2 , x3
6 real , dimension (N) , intent ( out ) : : x4
7 ! l o c a l v a r i a b l e s
8 real , dimension (N) : : xtend0 , xtend1 , xtend2 , xtend3
9 c a l l tend (x0 , xtend0 ,N)
10 c a l l tend (x1 , xtend1 ,N)
11 c a l l tend (x2 , xtend2 ,N)
12 c a l l tend (x3 , xtend3 ,N)
13 x4 = x3 + 1.0/24.0 * dt * ( 55*xtend3 − 59*xtend2 + 37*xtend1 − 9*xtend0 )
14 end subroutine
38. .
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Ch2 数值计算
有限差分方法
Demo
Fortran Code 1/2
1 program main
2
3 i m p l i c i t none
4
5 real , parameter : : PI = 3.1415926
6 integer , parameter : : N = 16 ! number of points
7 real , dimension (N) : : x , sinx , cosx
8 integer , dimension (N) : : pr , pl ! pointer
9
10 integer : : i
11 r e a l : : d
12 r e a l : : backward1 , forward1 , central2 , central4
13 r e a l : : bw1, fw1 , cen2 , cen4
14
15 !−−− i n i t −−−
16 d = 2.0* PI/ r e a l (N)
17 do i = 1 , N
18 x( i ) = ( r e a l ( i )−0.5)*d
19 sinx ( i ) = sin (x( i ))
20 cosx ( i ) = cos (x( i ))
21 pl ( i ) = i−1
22 pr ( i ) = i+1
23 end do
24 pl (1) = N
25 pr (N) = 1
39. .
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Ch2 数值计算
有限差分方法
Demo
Fortran Code 2/2
27 !−−− d( sinx )/dx = cosx−−−
28 do i = 1 , N
29
30 backward1 = ( sinx ( i)−sinx ( pl ( i )))/ d
31 forward1 = ( sinx ( pr ( i ))−sinx ( i ))/d
32 central2 = ( sinx ( pr ( i ))−sinx ( pl ( i )))/(2.0* d)
33 central4 = ( sinx ( pl ( pl ( i )))−8.0* sinx ( pl ( i ))+8.0* sinx ( pr ( i ))
34 −sinx ( pr ( pr ( i ))))/(12.0* d)
35
36 bw1 = backward1−cosx ( i )
37 fw1 = forward1−cosx ( i )
38 cen2 = central2−cosx ( i )
39 cen4 = central4−cosx ( i )
40
41 ! 输 出 绝 对 值
42 ! p r i n t ”(7 f10 .4)” , x( i ) , sinx ( i ) , cosx ( i ) , backward1 , forward1 ,
43 central2 , central4
44 ! 输 出 差 异 值
45 p r i n t ”(7 f10 .4) ” , x( i ) , sinx ( i ) , cosx ( i ) ,bw1, fw1 , cen2 , cen4
46
47 end do
48
49 end program
41. .
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Ch2 数值计算
有限差分方法
Demo
Plotting
1 # Plotting s c r i p t
2 # Xinyu Wen, Peking Univ , Mar 2015
3
4 set term post eps color s o l i d enh
5 set output ” d i f f . eps”
6
7 set x l a b e l ”x”
8 set y l a b e l ” sin (x)”
9
10 set yrange [ −0.5:0.5]
11 set xrange [ 0 : 6 . 2 8 ]
12
13 set t i t l e ”d( sinx )/dx”
14
15 plot ” r e s u l t ” u 1:4 t ”Backward” w l lw 4 , ” r e s u l t ” u 1:5 t ”Forward” w l lw 4 ,
16 ” r e s u l t ” u 1:6 t ” Central−2” w l lw 4 , ” r e s u l t ” u 1:7 t ” Central−4” w l lw 4
17
18 # in case you want to stop for a sec
19 #pause −1
52. .
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Ch2 数值计算
有限差分方法
Numerical errors
Demo 2: 大吃小?
1 program bigplussmall
2
3 i m p l i c i t none
4
5 r e a l : : big , small , plus , minus
6 integer : : i
7
8 big = 1.23456789
9 small = 0.00000001
10 plus = big + small
11 minus = big − small
12
13 pr in t ”(3 f20 .10) ” , big , small , plus
14 pr in t ”(3 f20 .10) ” , big , small , minus
15 pr in t ”(1 f20 .10) ” , 1.2345679
16 pr in t * , ”Another␣Test : ”
17 pr in t ”(1 f20 .10) ” , plus+small *100000
18
19 do i = 1 , 100000
20 plus = plus + small
21 end do
22
23 pr in t ”(1 f20 .10) ” , plus
24
25 end program
75. .
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Ch2 数值计算
谱方法
Discrete Fourier Transform
离散傅里叶变换(实数)
Discrete Fourier Transform (real)
Synthesis
1 subroutine idft_1d_real (a , b ,N, x)
2
3 i m p l i c i t none
4
5 integer , intent ( in ) : : N
6 real , dimension (0:N/2) , intent ( in ) : : a , b
7 real , dimension (1:N) , intent ( out ) : : x
8
9 integer i , k
10
11 do i = 1 , N
12 x( i ) = 0.0
13 do k = 0 , N/2
14 x( i ) = x( i ) + a(k)* cos (2.0* Pi*k* i /N) + b(k)* sin (2.0* Pi*k* i /N)
15 end do
16 end do
17
18 end subroutine
99. .
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Ch2 数值计算
谱方法
Legendre polynomials and Associated Legendre polynomials
Fortran Subroutine
1 function lp_fast (n , x) r e s u l t ( lpreturn )
2
3 i m p l i c i t none
4 integer , intent ( in ) : : n
5 real , intent ( in ) : : x
6 r e a l : : lpreturn
7
8 !−−− l o c a l
9 r e a l : : lp0 , lp1
10 integer : : i
11
12 lp0 = 1.000000
13 i f (n==0) then
14 lpreturn = lp0 ; return
15 end i f
16
17 lp1 = x
18 i f (n==1) then
19 lpreturn = lp1 ; return
20 end i f
21
22 !−−− P_n(x ) , for n>1
23 do i = 2 , n
24 lpreturn = ((2.0*( i −1)+1.0)*x*lp1−(i −1)*lp0 )/ i
25 lp0 = lp1
26 lp1 = lpreturn
27 end do
28
29 end function
106. .
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Ch2 数值计算
谱方法
Legendre polynomials and Associated Legendre polynomials
Fortran Subroutine 1/2
1 function a l f ( l ,m, x)
2
3 i m p l i c i t none
4 integer , intent ( in ) : : l , m
5 real , intent ( in ) : : x
6 r e a l : : a l f
7
8 !−−− l o c a l v a r i a b l e s
9 integer : : i , l l
10 r e a l : : fact , pll , pmm, pmmp1, somx2
11
12 !−−− s t a r t here
13 i f (m. l t .0 . or . m. gt . l . or . abs (x ) . gt .1) then
14 stop ”Wrong␣arguments␣ in ␣ [ a l f ] ␣ function ! ! ! ”
15 end i f
16
17 !−−− compute P_m^m
18 pmm = 1.0
19 i f (m. gt .0) then
20 somx2 = sqrt ((1.0−x)*(1.0+x ))
21 fact = 1.0
22 do i = 1 , m
23 pmm = −pmm* fact *somx2
24 fact = fact +2.0
25 end do
26 end i f
27 i f ( l . eq .m) then
28 a l f = pmm; return
29 end i f
107. .
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Ch2 数值计算
谱方法
Legendre polynomials and Associated Legendre polynomials
Fortran Subroutine 2/2
31 !−−− compute P_(m+1)^m
32 pmmp1 = x*(2*m+1)*pmm
33 i f ( l . eq .m+1) then
34 a l f = pmmp1
35 return
36 end i f
37
38 !−−− integrate u n t i l P_l^m
39 do l l = m+2, l
40 p l l = (x*(2* l l −1)*pmmp1−( l l+m−1)*pmm)/( l l −m)
41 pmm = pmmp1
42 pmmp1 = p l l
43 end do
44 a l f = p l l
45
46 !−−− normalize
47 a l f = a l f * sqrt ( f a c t o r i a l ( l−m)/ f a c t o r i a l ( l+m))
48 end function
其中 factorial 是一个求阶乘的函数,由于代码很简单这里从简