Учебники / [Филяев К.Ю.] Математические задачи энергетики
.pdf. 11, …, 14 – ; D –
.
D ,
( ) -
, .
. , ,
, :
D = 0. (2.8)
-
, (2.3) .
( ) [1.8, §4.2; 1.9, §12.2]: 1. .
( = 0),
U = 0) ( 1, 2 = const) -
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dPi = 0 , |
(2.9) |
dδi |
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i = 1, 2, ….
2. .
= 0 -
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d Q |
= 0 , |
(2.10) |
dU |
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Q = Q – (Q + Q ).
. 2.2 ,
, . 1, . -
, U = (E – QX/E)/cos . , → 90 (
) dU/dE = 1/cos2 →
dE |
= 0. |
(2.11) |
dU |
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91
. 2.2
(2.5) (2.6) ,
< 90 ( . ∂ /∂ 0) ∂ /∂U = 0 -
Q -
U. .
.
, -
( ) -
,
: |
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dP/d = 0 |
(2.12 ) |
, = d /dt = s, |
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dP/ds = 0. |
(2.12 ) |
-
[1.8, . 4.1].
, -
, -
. , . -
, ,
92
12 = 1 – 2 Pi = f 12, 1, 2), i = 1,2.
(2.1) :
ì¶Dw |
Dd12 |
- Dw1 + Dw2 = 0; |
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ï ¶P1 |
Dd12 |
+ |
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Dw1 + |
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= DP1; |
(2.13) |
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Dd + |
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= DP . |
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, =1 – 2 0. (2.8)
0 -1 1
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D = ¶d12 |
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(2.14) |
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(2.3),
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÷Dw = 0 . |
(2.15 ) |
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1 = 2 = , |
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D = |
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(2.15 ) |
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-
,
. -
93
, , , -
( ).
.
(2.4) 10:
åm (a ji p2 + b jip + c ji = ϕj(p ). |
(2.16) |
j,i=1 |
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ϕj(p) – . -
m |
D |
ji |
(p |
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xi (p )= å |
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ϕj (p ), |
(2.17) |
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D(p ) |
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j=1 |
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D(p) – , ;
Dji(p) – , j i
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(2.17) xi(t). -
, . ϕj( ) = 0, , -
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D(p) = a0pn + a1pn–1 + … + an = 0 |
(2.18) |
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____________________________________________________________________
10 -
) «
» « ».
94
pk (2.18) 11, (2.17)
n m |
D |
ji |
(p |
k |
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xi (t )= åå |
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ϕj(pk e)p k t . |
(2.19) |
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k =1j=1 |
D(pk ) |
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(2.19) -
[1.8, §8.1]. (– ; t0), t0
0, fj(t0) -
. t0 , -
xi(t0), , -
(2.18)
x |
(t )= C ep1t |
+ C |
2i |
ep2 t + K+ C |
ni |
ep n t . |
(2.19 ) |
i |
1i |
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, -
, . pk = αk
(2.19 ) Ckieα k t ,
ps,s+1 = αs ± jωs – Csie(αs + jωs )t + C(s+1)ie(αs − jωs )t . Csi
C(s+1)i – : si = Asi – jBsi, si = Asi + jBsi,
Csie(αs + jωs )t + C(s+1)ie(αs − jωs )t = 2Csi eαs t sin(ωst + ϕsi ,
Csi = Asi2 + Bsi2 ; ϕsi = arctg(Asi Bsi .
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11 f(x) , , f(c) = 0.
, f(x) ( – )
, . k-
, f(x) ( – )k, ( – )k+1, k N. k . k =1, -
, – .
95
, ,
-
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, -
( ) . -
αs,
, -
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, -
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2.3.6.
(2.18)
. -
. .
, , -
, .
) ( D- , ,
). -
D- .
: [1.8, §8.2] ,
, -
96
, 1, , …, n,
(2.18), , 0 > 0.
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a1 |
a3 |
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a5 |
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1 = a1; |
2 = |
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3 = |
a0 |
a2 |
a4 |
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a2 |
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a1 |
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L 0 |
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a0 |
a2 |
a4 |
L 0 |
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n = |
0 |
a1 |
a3 |
L |
0 |
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(2.20) |
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a2 |
L 0 |
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L L L |
L L |
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0 |
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[1.2, . VII, §15; 1.3, . III, §2; 2.3, §§4, 5].
n n–1- :
1) 1 n -
; 2) -
, – -
; 3) , -
;
4), -
n , ;
5)n n–1 = n/an.
-
n , . n = an n–1 n–1 > 0 ,
n > 0.
:
97
.
n ( n–1).
, -
, -
. -
– -
. -
: -
12 -
, – .
n 4. -
.
2.4.
2.4.1.
( ,
, , ,
)
____________________________________________________________________
12 – ( ,
.), .
98
, , -
.
( = ϕ ), Q = ψ ) .) , ,
, -
.
, ,
,
.
, ,
E
= E’ = const. , -
. 2.3, , -
13
P = E2Y |
sin α |
+ EUY |
sin(δ − α , |
(2.21 ) |
11 |
11 |
12 |
12 |
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Y11 = Y12 = 1/|Z|; Z = j( + 2 ); α11 = α12 = π/2 – arctg(Im(Z)/Re(Z)). -
,
P = EUY12 sin δ
P = |
EU sin δ. |
(2.21 ) |
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X |
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12 |
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, -
, = /ω. ω
(100 – 200
), ω 1 – 2%
ω0 (ω0 = 360*50 = 18000 ). ω = ω0 + ω ≈ ω0,
( ω0* = 1)
____________________________________________________________________
13 -
» ».
99
: * = *. ,* = *.
. 2.3. ,
( . 2.3,
. 2.3, ), . -
, , , -(2.21 ) ( . 2.4, ).
, ,
I II.
MI0 = MII0 ¹ ( . 2.4, ).
0 = – II ,
w. -
-
, -
, ,
,
100