Research Article Asymptotic Estimates of the Solution of a ...Asymptotic Estimates of the Solution...
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Research ArticleAsymptotic Estimates of the Solution of a RestorationProblem with an Initial Jump
Duisebek Nurgabyl
Institute of Postgraduate Education and Staff Retraining, Zhetysu State University Named after I. Zhansugurov,187A Zhansugurov Street, Taldykorgan 040000, Kazakhstan
Correspondence should be addressed to Duisebek Nurgabyl; [email protected]
Received 18 September 2013; Accepted 20 January 2014; Published 27 April 2014
Academic Editor: Debasish Roy
Copyright Β© 2014 Duisebek Nurgabyl. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The asymptotic behavior of the solution of the singularly perturbed boundary value problemπΏππ¦ = β (π‘) π, πΏ
ππ¦+πππ = π
π, π = 1, π + 1
is examined.The derivations prove that a unique pair (π¦ (π‘, οΏ½ΜοΏ½ (π) , π) , οΏ½ΜοΏ½ (π)) exists, in which componentsπ¦(π‘, οΏ½ΜοΏ½ (π) , π) and οΏ½ΜοΏ½(π) satisfythe equation πΏ
ππ¦ = β(π‘)π and boundary value conditions πΏ
ππ¦ + π
ππ = π
π, π = 1, π + 1. The issues of limit transfer of the perturbed
problem solution to the unperturbed problem solution as a small parameter approaches zero and the existence of the initial jumpphenomenon are studied. This research is conducted in two stages. In the first stage, the Cauchy function and boundary functionsare introduced. Then, on the basis of the introduced Cauchy function and boundary functions, the solution of the restorationproblem πΏ
ππ¦ = β (π‘) π, πΏ
ππ¦+ πππ = π
π, π = 1, π + 1 is obtained from the position of the singularly perturbed problem with the initial
jump.Through this process, the formula of the initial jump and the asymptotic estimates of the solution of the considered boundaryvalue problem are identified.
1. Introduction
One of the fundamental theorems of singular perturbationstheories is Tikhonovβs theorem [1, 2] on the limit transitionthat establishes the limit equations, expressing the relationsbetween the solutions of a degenerate problem and an orig-inal singularly perturbed initial problem, and this theoremallows us to obtain the leading member of asymptotics.
For a wide class of the singularly perturbed problems,effective asymptotic methods were developed, allowing forthe development of uniform approximations with any levelof precision. The methods of VisΜik and Lyusternik [3] andVasilyeva [4] were the first methods to be developed, whichare called methods of boundary functions. Butuzov [5]developed a method of angular boundary functions, whichwas a significant development for the boundary functionsmethod.
Each of these methods has a certain area of applicability;that is, they are successful in solving some problems andare invalid when solving other problems. For example, therewere some fundamental difficulties in the realization of
the boundary functions method in problems with initialjumps. The beginning of the mathematical solution of theinitial jump phenomenon was considered in the studies ofVisΜik and Lyusternik [6] and Kasymov [7], in which themethod of zone integration for nonlinear singularly per-turbed initial tasks with unbounded initial data when a smallparameter approaches zero. The research efforts of VisΜik,Lyusternik, and Kasymov were continued in [8, 9] and otherstudies.
Simultaneously, there were problems in practice thatextended beyond the scope of traditional research, inwhich ready-made asymptotic methods were inapplicableand required modification or generalization. For example,in the study of NeΜΔ±mark and Smirnova [10], a new rationaleof the physical and mathematical nature of the Painleveparadox was introduced, which enriched the possible typesof movements and dynamics of the system as a whole. At thispoint, we saw the races and contrasting structures. ButuzovandVasiliyeva studiedmathematical solutions of the questionof contrast structures [11], and the phenomenon of the initialjump requires additional mathematical research.
Hindawi Publishing CorporationJournal of Applied MathematicsVolume 2014, Article ID 956402, 11 pageshttp://dx.doi.org/10.1155/2014/956402
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2 Journal of Applied Mathematics
Boundary value problems for ordinary differential equa-tions containing parameters in the right-hand side and in theboundary conditions were examined [12, 13]. In these studies,a restoration problem of the right-hand side of the differentialequations and boundary conditions is solved with the well-known structure of the differential equation and additionalinformation.
The following natural generalization in this direction is tostudy the solutions of singularly perturbed boundary valueproblems with an additional parameter having the initialjump phenomenon. Such a study has not yet been reported.This study considers such problems. It studies the problemsof solution building, restoring the right-hand side of theequation and boundary conditions of the perturbed problem,the limit solution passing of the perturbed problem solutionto the unperturbed problem solution.
2. Statement of the Problem
Let π = (ββ, β), π = [0, 1], where π‘ belongs to π = [0, 1].We consider
πΏππ¦ β‘ ππ¦
(π)
+ π΄1(π‘) π¦(πβ1)
+ β β β + π΄π(π‘) π¦ = β (π‘) π (1)
with nonseparated boundary conditions
πΏππ¦ + πππ = ππ, π = 1, π + 1, (2)
where
πΏππ¦ β‘
ππ
β
π=0
πΌπππ¦(π)
(0, π) +
ππ
β
π=0
π½πππ¦(π)
(1, π) , (3)
π > 0 is a small parameter, π is an unknown parameter,πΌππ, π½ππ, ππ, ππβ π are known constants, and π
π, ππ= fix β
{0, 1, . . . , π β 1}. Let the matrix
π = (
πΌ10
πΌ11
β β β πΌ1π1
π½10
π½11
. . . π½1π1
πΌ20
πΌ21
. . . πΌ2π2
π½20
π½21
. . . π½2π2
. . . . . . β β β . . . . . . . . .
πΌπ+1,0
πΌπ+1,1
. . . πΌπ+1,ππ+1,
π½π+1,0
π½π+1,1
. . . π½π+1,ππ+1,
) (4)
have a rank equal to π, where π is the maximum number oflinearly independent rows of matrix π. To the certainty, letthe first π rows of the matrix be linearly independent. Then,the linear forms πΏ
ππ¦, π = 1, π, as the functions of π¦(π)(0, π), π =
0,ππand π¦(π)(1, π), π = 0, π
πare linearly independent of each
other.Consider that
(a) π΄π(π‘) β πΆ
π
(π ), π = 1, π, β(π‘) β πΆ1
(π),(b) a constant πΎ is independent of π and is
π΄1(π‘) β₯ πΎ > 0, 0 β€ π‘ β€ 1, (5)
(c) inequalities
πΌ1π1
ΜΈ= 0, π β₯ 3,
π β 1 > π1> π2β₯ β β β β₯ π
π,
π β 1 > ππ, π = 1, π, π½
01ΜΈ= 0
(6)
are valid, where π½01is a determinant of (πβ1)th order, which is
obtained from the rectangular matrix πΏππ¦π0
(π = 1, . . . , π, π =
1, . . . , π β 1) as follows:
π½ = (
πΏ1π¦10
β β β πΏ1π¦πβ1,0
β β β β β β β β β
πΏππ¦10
β β β πΏππ¦πβ1,0
) , (7)
by deleting the first line, and π¦π0(π‘), π = 1, π β 1 is the funda-
mental system of the solutions of the following homogeneousunperturbed (degenerate) equation:
πΏ0π¦0β‘ π΄1(π‘) π¦(πβ1)
0+ β β β + π΄
π(π‘) π¦0= 0. (8)
Corresponding to (1),
(d) π· = π·π+1
β βπ
π=2π·ππΏπ+1
π½πβ1,1
(π‘)/π½01
ΜΈ= 0 is valid,
whereπ·π= ππ+βππ
π=0π½ππβ«1
0
(β(π )π(π)
π‘(1, π )/π΄
1(π )π(π ))ππ (π =
1, π + 1), π½πβ1,1
(π‘) is the (π β 1)th-order determinantobtained from π½
01by replacing the (π β 1)th row with the
π¦10(π‘), π¦20(π‘), . . . , π¦
πβ1,0(π‘) row, and π(π ) is the Wronskian
of the solution system π¦π0(π ), π = 1, π β 1, π(π)
π‘(π‘, π ) and the
(πβ1)th-order determinant obtained fromπ(π ) by replacingthe (π β 1)th row with the π¦(π)
10(π‘), . . . , π¦
(π)
πβ1,0(π‘) row.
(e) Consider
π
β
π=1
(β1)1+π
π½0π
Γ (ππβ π0ππβ π0
ππ
β
π=0
π½ππβ«
1
0
β (π )
π΄1(π )
π(π)
π‘(1, π )
π (π )
ππ ) ΜΈ= 0,
(9)
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where π½0πis the (πβ1)th-order determinant, which originates
from π½ by deleting the πth row, and π0
= (1/π·)(ππ+1
β
βπ
π=1πππΏπ+1
π½πβ1,1
(π‘)/π½01).
The problem lies in determining the pair(π¦(π‘, οΏ½ΜοΏ½(π), π), οΏ½ΜοΏ½(π)), where π¦(π‘, οΏ½ΜοΏ½(π), π) and οΏ½ΜοΏ½(π) satisfy(1) and the boundary conditions in (2), in building theasymptotic estimates of (1) and (2) problem solutions and inthe study of the initial jump phenomenon.
The following study is conducted according to a specificrule. In the first stage, we build the recovery problemsolutions (1) and (2) from the position of a singularlyperturbed problemwith the initial jump on the basis of initialand boundary functions. In the next stage, we study theasymptotic behavior of the boundary value problem solutions(1) and (2).
3. Fundamental Solution System
Along with (1), we consider the following correspondinghomogeneous perturbed equation:
πΏππ¦ = 0. (10)
We seek a fundamental solution system of (10) in thefollowing form:
π¦π(π‘, π) = π¦
π0+ ππ¦π1+ π2
π¦π2+ β β β , π = 1, π β 1,
π¦π(π‘, π) = exp(1
πβ«
π‘
0
π (π₯) ππ₯) (π¦π0+ ππ¦π1+ π2
π¦π2+ β β β ) ,
(11)
where π¦ππ(π‘) represents unknown functions to be found and
π(π‘) = βπ΄1(π‘).
By substituting (11) into (10) and by matching the coef-ficients of like powers of π on both sides of the resultingrelation, we obtain a sequence of equations for all terms inexpansion (11). For our aim, however, it suffices to considerthe zero approximation. So, for the zero approximation (forπ¦π0(π‘), π = 1, π β 1), we have the following problems:
πΏ0π¦π0= π΄1(π‘) π¦(πβ1)
π0+ β β β + π΄
π(π‘) π¦π0= 0, π = 1, π β 1,
π¦(π)
π0(0) = 1, π = π β 1, π¦
(π)
π0(0) = 0, π ΜΈ= π β 1,
π = 0, π β 2, π = 1, π β 1,
π΄1(π‘) π¦
π0(π‘) + [(π β 1)π΄
1(π‘) β π΄
2(π‘)] π¦π0(π‘) = 0,
π¦π0(0) = 1.
(12)
Unique solutions exist for the problems (12) on theinterval 0 β€ π‘ β€ 1, and they form the fundamental solutionsystem π¦
π0(π‘), π = 1, π β 1 for the following homogeneous
equation:
πΏ0π¦0β‘ π΄1(π‘) π¦(πβ1)
0+ β β β + π΄
π(π‘) π¦0= 0, (13)
where π¦π0(π‘) is presented in the following form:
π¦π0(π‘) = (
π΄1(0)
π΄1(π‘)
)
πβ1
exp(β«π‘
0
(π΄2(π₯)
π΄1(π₯)
) ππ₯) . (14)
Lemma 1. Let conditions (a) and (b) be satisfied. Then, thefundamental solution system π¦
π(π‘, π), π = 1, π of the singularly
perturbed equation (10) permits the following asymptoticrepresentations:
π¦(π)
π(π‘, π) = π¦
(π)
π0(π‘) + π (π) , π = 1, π β 1, π = 0, π β 1,
π¦(π)
π(π‘, π) =
1
ππexp(1
πβ«
π‘
0
π (π₯) ππ₯)
β π¦π0(π‘) ππ
(π‘) (1 + π (π)) , π = 0, π β 1,
(15)
as π β 0.
The proof of the lemma is readily obtained from the well-known theorems of Schlesinger [14] and Birkhoff [15] (e.g.,see [16]).
Let us introduce the Wronskian determinant π(π‘, π) forthe fundamental solution system π¦
π(π‘, π), π = 1, π of (9) and
expand it in entries of the πth column:
π(π‘, π) = (β1)1+π
π¦π(π‘, π)π
1(π‘, π) + β β β
+ (β1)2π
π¦(πβ1)
π(π‘, π)π
π(π‘, π) ,
(16)
whereππ(π‘, π), π = 1, π is (π β 1)th order.
With regard to (15), we obtain
ππ(π‘, π) = π
π0(π‘) + π (π) , π = 1, π, (17)
for sufficiently small π for ππ(π‘, π), where π
π0(π‘) is obtained
from the rectangular matrix (π¦(πβ1)π0
(π‘)) (π = 1, . . . , π, π =
1, . . . , π β 1) by deleting the πth row. In particular, thedeterminant π
π0(π‘) β‘ π(π‘) is the Wronskian of the
fundamental solution system π¦10(π‘), π¦20(π‘), . . . , π¦
πβ1,0(π‘) of
(13). With regard to (15) and (17), the expression (16) acquiresthe following form:
π(π‘, π) = (β1)1+π exp(1
πβ«
π‘
0
π (π₯) ππ₯)
Γ π¦π0(π‘) (π
10(π‘) + π (π))
+(β1)2+π
πexp(1
πβ«
π‘
0
π (π₯) ππ₯)
β π¦π0(π‘) π (π‘) (π
20(π‘) + π (π)) + β β β
+ (β1)2πβ1
1
ππβ2exp(1
πβ«
π‘
0
π (π₯) ππ₯)
β π¦π0(π‘) ππβ2
(π‘) β (ππβ1,0
(π‘) + π (π))
+ (β1)2π
1
ππβ1exp(1
πβ«
π‘
0
π (π₯) ππ₯)
β π¦π0(π‘) ππβ1
(π‘) (π (π‘) + π (π)) .
(18)
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Hence, considering that the last summand is dominant, whenπ β 0 for the Wronskian determinant, it implies theasymptotic representation
π(π‘, π) =π (π‘)
ππβ1π¦π0(π‘) ππβ1
(π‘) β exp(1πβ«
π‘
0
π (π₯) ππ₯)
Γ (1 + π (π)) ΜΈ= 0, 0 β€ π‘ β€ 1,
(19)
where π¦π0(π‘) is given by (14).
4. Cauchy Function and Boundary Functions
Following previous work [17], let us introduce the Cauchyfunction.
Definition 2. Function πΎ(π‘, π , π), defined at 0 β€ π β€ π‘ β€1, is called the Cauchy function of (10), if it satisfies thehomogeneous equation (10) according to π‘ and within π‘ = π initial conditions:
πΎ(π)
(π , π , π) = 0, π = 0, π β 2, πΎ(πβ1)
(π , π , π) = 1.
(20)
The following theorem is valid.
Theorem 3. Let conditions (a) and (b) be satisfied. Then, forsufficiently small π, the Cauchy functionπΎ(π‘, π , π) with 0 β€ π β€π‘ β€ 1 exists, is unique, and is expressed as follows:
πΎ (π‘, π , π) =π (π‘, π , π)
π (π , π), (21)
whereπ(π‘, π , π) is the πth order determinant obtained from theWronskianπ(π , π) by replacing the πth row of the fundamentalsolution system with π¦
1(π‘, π), π¦
2(π‘, π), . . . , π¦
π(π‘, π) of (10).
Lemma 4. If conditions (a) and (b) are satisfied, then, forsufficiently small π, the Cauchy functionπΎ(π‘, π , π) with 0 β€ π β€π‘ β€ 1 can be represented in the following form:
πΎ(π)
π‘(π‘, π , π) =
π
π (π )π (π )
β (βπ(π)
πβ1,0(π‘, π ) + π (π)) ,
π = 0, π β 3,
πΎ(πβ2)
π‘(π‘, π , π) = π ( β
π(πβ2)
πβ1,0(π‘, π )
π (π )π (π )
+π¦π0(π‘) ππβ2
(π‘)
π¦π0(π ) ππβ1
(π )
Γ exp(1πβ«
π‘
π
π (π₯) ππ₯) + π (π)) ,
πΎ(πβ1)
π‘(π‘, π , π) = β π
π(πβ1)
πβ1,0(π‘, π )
π (π )π (π )
+π¦π0(π‘) ππβ1
(π‘)
π¦π0(π ) ππβ1
(π )e(1/π) β«
π‘
π π(π₯)ππ₯
+ π(π2
+ π exp(1πβ«
π‘
π
π (π₯) ππ₯)) ,
(22)
whereππβ1,0
(π‘, π ) is the determinant obtained from the Wron-skianπ(π ) by substituting the (πβ 1)th row with the π¦
π0(π‘), π =
1, π β 1 row.
Proof. By expandingπ(π)π‘
(π‘, π , π), π = 0, π β 1 in entries of theπth column, we obtain
π(π)
π‘(π‘, π , π) =
πβ1
β
π=1
(β1)π+π
π¦(πβ1)
π(π , π)
Γ οΏ½ΜοΏ½(π)
π(π‘, π , π) + (β1)
2π
π¦(π)
π(π‘, π) οΏ½ΜοΏ½
π(π , π) .
(23)
From (15), theminors οΏ½ΜοΏ½(π)π
(π‘, π , π), οΏ½ΜοΏ½π(π , π) for sufficiently
small π > 0 can be represented in the following form:
οΏ½ΜοΏ½(π)
π(π‘, π , π) = π
(π)
π0(π‘, π ) + π (π) , π = 1, π β 1,
οΏ½ΜοΏ½π(π , π) = π
π0(π ) + π (π) ,
(24)
where ππ0(π ) = π(π ) and π(π)
π0(π‘, π ) is the determi-
nant obtained from the rectangular matrix (π¦(πβ1)π0
(π )) (π =
1, . . . , π, π = 1, . . . , πβ1) by deleting the πth row and replacingthe (π β 1)th row with the (π¦(π)
10(π ), . . . , π¦
(π)
πβ10(π )) row.
Then, from (23) and (15), relation (24) acquires thefollowing form:
π(π)
π‘(π‘, π , π) =
πβ1
β
π=1
(β1)π+π
1
ππβ1exp(1
πβ«
π
0
π (π₯) ππ₯)
Γ π¦π0(π ) ππβ1
(π ) (π(π)
π0(π‘, π ) + π (π))
+ (β1)2π
1
ππexp(1
πβ«
π‘
0
π (π₯) ππ₯)
Γ π¦π0(π‘) ππ
(π‘) (π (π ) + π (π)) .
(25)
This readily implies that
π(π)
π‘(π‘, π , π) =
1
ππβ2π¦π0(π ) ππβ1
(π ) exp(1πβ«
π
0
π (π₯) ππ₯)
Γ [
[
β
π(π)
πβ1,0(π‘, π )
π (π )+ππβ2
ππ
π¦π0(π‘) ππ
(π‘)
π¦π0(π ) ππβ1
(π )
Γ π (π ) exp(1πβ«
π‘
π
π (π₯) ππ₯)
+π(π + ππβ1βπ exp(1
πβ«
π‘
π
π (π₯) ππ₯))]
]
.
(26)
From (26) with regard to (19) and (21), we obtain thedesired estimates (22).
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Journal of Applied Mathematics 5
Definition 5. Functions Ξ¦π(π‘, π), π = 1, π are referred to as
boundary functions of the boundary value problems (1) and(2), if they satisfy the homogeneous equation (10) and theboundary conditions
πΏπΞ¦π= πΏππ, π, π = 1, . . . , π. (27)
Consider the determinant
π½ (π) = det (πΏππ¦π) , π, π = 1, . . . , π, (28)
where with (15), the entries πΏππ¦π
= βππ
π=0πΌπππ¦(π)
π(0, π) +
βππ
π=0π½πππ¦(π)
π(1, π) can be represented in the following form:
πΏππ¦π=
ππ
β
π=0
πΌπππ¦(π)
π0(0) +
ππ
β
π=0
π½πππ¦(π)
π0(1) + π (π) ,
π = 1, π, π = 1, π β 1,
πΏππ¦π=
ππ
β
π=0
ππ
(0)
πππΌππ(1 + π (π)) +
ππ
β
π=0
ππ
(1)
πππ½πππ¦π0(1)
Γ exp(1πβ«
1
0
π (π₯) ππ₯) (1 + π (π)) .
(29)
This, togetherwith the estimate exp((1/π) β«10
π(π₯)ππ₯) = π(ππ
)
(whereπ is an arbitrary positive integer), implies that
πΏππ¦π= πΏππ¦π0+ π (π) , πΏ
ππ¦π=πππ (0)
πππ(πΌπππ
+ π (π)) ,
π = 1, π, π = 1, π β 1,
(30)
where
πΏππ¦π0
=
ππ
β
π=0
πΌπππ¦(π)
π0(0) +
ππ
β
π=0
π½πππ¦(π)
π0(1) , π = 1, π,
π = 1, π β 1.
(31)
Now, let us expand π½(π) in the entries of the last column:
π½ (π) = (β1)1+π
πΏ1π¦πβ π½1(π) + β β β + (β1)
2π
πΏππ¦πβ π½π(π) . (32)
Here, from (15), the minors π½π(π) can be expressed in the
following form:
π½π(π) = π½
0π+ π (π) , π = 1, π, (33)
where π½0πis the (π β 1)th-order determinant introduced in
Section 1.By substituting (30) and (33) into (32), we obtain
π½ (π) = (β1)1+π
ππ1 (0)
ππ1(πΌ1π1
π½01+ π (π)) + β β β
+ (β1)2ππππ (0)
πππ(πΌπππ
π½0π+ π (π)) .
(34)
This, together with condition (c), implies that the determi-nant (28) permits the asymptotic representation:
π½ (π) = (β1)1+π
1
ππ1πΌ1π1
ππ1
(0) π½01(1 + π (π)) ΜΈ= 0. (35)
The following theorem is valid.
Theorem 6. Let conditions (a)β(c) be satisfied. Then, forsufficiently small π > 0, the boundary functions Ξ¦
π(π‘, π), π =
1, π exist on the interval [0, 1], are unique, and are given asfollows:
Ξ¦π(π‘, π) =
π½π(π‘, π)
π½ (π), π = 1, π, (36)
where π½π(π‘, π) is the determinant obtained from π½(π) by sub-
stituting the πth row with the fundamental solution systemπ¦π(π‘, π), π = 1, π of (10).
Lemma 7. If conditions (a)β(c) are satisfied, then the bound-ary functions Ξ¦
π(π‘, π), π = 1, π permit the asymptotic
representations:
Ξ¦(π)
1(π‘, π) =
1
π½01
[βππ1βπ2
πΌ2π2
ππ2 (0)
πΌ1π1
ππ1 (0)π½(π)
12(π‘)
+ ππ1βπ
π¦π0(π‘)
πΌ1π1
ππ
(π‘)
ππ1 (0)π½01
Γ exp(1πβ«
π‘
0
π (π₯) ππ₯)
+ π(π1+π1βπ2 + π
π1+1βπ
Γ exp(1πβ«
π‘
0
π (π₯) ππ₯))] ,
(37)
Ξ¦(π)
π(π‘, π) =
π½(π)
πβ1,1(π‘)
π½01
+ (β1)πβ1
ππ1βπ
π¦π0(π‘) ππ
(π‘)
πΌ1π1
ππ1 (0)
β π½0π
π½01
exp(1πβ«
π‘
0
π (π₯) ππ₯)
+ π(π + ππ1+1βπ exp(1
πβ«
π‘
0
π (π₯) ππ₯)) ,
π = 2, . . . , π, π = 0, π β 1,
(38)
on the closed interval [0, 1] as π β 0, where π½01
and π½0π
arethe determinants introduced in Section 1, π½(π)
12(π‘) = π½
(π)
21(π‘), and
π½(π)
πβ1,1(π‘) is the (π β 1)th-order determinant obtained from π½
01
by replacing the (πβ1)th row with the π¦(π)10(π‘), . . . , π¦
(π)
πβ10(π‘) row.
-
6 Journal of Applied Mathematics
Proof. From (36), we define the derivative π½(π)1(π‘, π) of the
functionπ½1(π‘, π). Let us expand π½(π)
1(π‘, π) in the entries of the
πth column:
π½(π)
1(π‘, π) = (β1)
1+π
π¦(π)
π(π‘, π) π½
01π(π)
+ (β1)2+π
πΏ2π¦ππ½12π
(π‘, π) + β β β
+ (β1)2π
πΏππ¦ππ½1ππ
(π‘, π) .
(39)
Here in the minors π½011
(π), π½1ππ
(π‘, π), (π = 1, π), the firstsubscript represents the number of the row containing thesystem of functions π¦(π)
1(π‘, π), . . . , π¦
(π)
πβ1(π‘, π). From (30), the
determinants π½011
(π), π½1ππ
(π‘, π), (π = 1, π) can be presented inthe following form:
π½011
(π) = π½01+ π (π) , π½
1ππ(π‘, π) = π½
(π)
1π(π‘) + π (π) ,
π = 2, π,
(40)
where the determinants π½(π)1π(π‘) are obtained from π½
0πby
substituting the first row with the π¦(π)10(π‘) β β β π¦
(π)
πβ1,0(π‘) row.
With regard to (15), (30), and (40), the expression π½(π)1(π‘, π)
acquires the following form:
π½(π)
1(π‘, π) = (β1)
1+π1
ππexp(1
πβ«
π‘
0
π (π₯) ππ₯)
Γ ππ
(π‘) π¦π0(π‘) (π½01+ π (π)) + (β1)
2+π
Γππ2 (0)
ππ2(πΌ2π2
π½(π)
12(π‘) + π (π)) + β β β
+ (β1)2ππππ (0)
πππ(πΌπππ
π½(π)
1π(π‘) + π (π)) ,
π = 0, π β 1.
(41)
This, together with the condition (c), gives the followingrepresentation:
π½(π)
1(π‘, π) =
(β1)π+1
ππ2
Γ [ β πΌ2π2
ππ2
(0) π½(π)
12(π‘)
+ ππ2βπππ
(π‘) π¦π0(π‘) π½01exp(1
πβ«
π‘
0
π (π₯) ππ₯)
+ π(π + ππ2+1βπ exp(1
πβ«
π‘
0
π (π₯) ππ₯))] ,
π = 0, π β 1.
(42)
Taking into account (35), (42), and (36), we obtainrelation (37) forΞ¦(π)
1(π‘, π).
Now, we expand π½(π)π(π‘, π) in the entries of the πth column:
π½(π)
π(π‘, π) = (β1)
1+π
πΏ1π¦ππ½πβ1,1
(π‘, π) + β β β
+ (β1)πβ1+π
πΏπβ1
π¦ππ½πβ1,πβ1
(π‘, π)
+ (β1)π+π
π¦(π)
π(π‘, π) π½
0π(π)
+ (β1)π+1+π
πΏπ+1
π¦ππ½π,π+1
(π‘, π)
+ β β β + (β1)2π
πΏππ¦ππ½ππ(π‘, π) .
(43)
Here the first subscript in the determinants π½0π, π½(π)
πβ1,π(π =
1, π β 1), π½(π)
ππ(π = π + 1, π) indicates the row containing
the system of the functions π¦(π)1(π‘, π) β β β π¦
(π)
πβ1(π‘, π), and the
second subscript shows that they are the minors of the entryof the determinant π½(π)
π(π‘, π) at the intersection of the πth
row and πth column. From (30), the minors π½0π, π½(π)
πβ1,π(π =
1, π β 1), π½(π)
ππ(π = π + 1, π) can be presented in the following
form:
π½0π(π) = π½
0π+ π (π) , π½
(π)
πβ1,π(π‘, π) = π½
(π)
πβ1,π(π‘) + π (π) ,
π = 1, π β 1,
π½(π)
ππ(π‘, π) = π½
(π)
ππ(π‘) + π (π) , π = π + 1, π,
(44)
where π½0π
is as defined in Section 1, π½(π)πβ1,π
(π‘) (π = 1, π β 1) isobtained from π½
0π(π = 1, . . . , π β 1) by replacing the (π β 1)th
row with the π¦(π)10(π‘) β β β π¦
(π)
πβ1,0(π‘) row, and π½(π)
ππ(π‘) (π = π + 1, π)
is obtained from π½0π(π = π + 1, . . . , π) by replacing the πth
with the π¦(π)10(π‘) β β β π¦
(π)
πβ1,0(π‘) row.
In view of (30) and (44) out of (43), the expression takesthe following form:
π½(π)
π(π‘, π) = (β1)
1+πππ1 (0)
ππ1(πΌ1π1
π½(π)
πβ1,1(π‘) + π (π)) + β β β
+ (β1)πβ1+π
πππβ1 (0)
πππβ1
Γ (πΌπβ1,ππβ1
π½(π)
πβ1,πβ1(π‘) + π (π))
+ (β1)π+π
π¦π0(π‘)
ππππ
(π‘) exp(1πβ«
π‘
0
π (π₯) ππ₯)
Γ (π½0π+ π (π)) + (β1)
π+1+π
Γπππ+1 (0)
πππ+1(πΌπ+1,ππ+1
π½(π)
π,π+1(π‘) + π (π)) + β β β
+ (β1)2ππππ (0)
πππ
Γ (πΌπππ
π½(π)
ππ(π‘) + π (π)) , π = 0, π β 1.
(45)
-
Journal of Applied Mathematics 7
Here the expression (β1)1+π(ππ1(0)/ππ1)πΌ1π1
π½(π)
πβ1,1(π‘) is
dominant for small π. Then, considering condition (c), we getthe following asymptotic representation for π½(π)
π(π‘, π):
π½(π)
π(π‘, π) =
(β1)π+1
ππ1
Γ [πΌ1π1
ππ1
(0) π½(π)
πβ1,1(π‘)
+ (β1)πβ1
ππ1βπππ
(π‘) π¦π0(π‘) π½0π
Γ exp(1πβ«
π‘
0
π (π₯) ππ₯)
+ π(π + ππ1+1βπ exp(1
πβ«
π‘
0
π (π₯) ππ₯))] ,
π = 2, π, π = 0, π β 1.
(46)
Substituting (35) and (46) into formula (36), we obtain theasymptotic formula (38) for the boundary functionsΞ¦(π)
π(π‘, π).
The proof of the lemma is complete.
5. Analytic Representation andEstimates of the Solution
Consider the singularly perturbed boundary value problems(1) and (2). The unique solution of the problems (1) and (2) isfound in the following form:
π¦ (π‘, π, π) = π1Ξ¦1(π‘, π) + β β β + π
πΞ¦π(π‘, π)
+π
πβ«
π‘
0
πΎ (π‘, π , π) β (π ) ππ ,
(47)
where Ξ¦π(π‘, π), π = 1, π are the boundary functions, πΎ(π‘, π , π)
is the Cauchy function, π1, π2, . . . , π
πare unknown consonants,
and π is the required parameter. By a straightforward ver-ification, one can show that the function π¦(π‘, π, π), definedby formula (47), is identical to (1). For the determinationof π1, π2, . . . , π
π, π, we substitute (47) into the boundary
conditions (b). Then, with regard to the boundary (27), weobtain the following system of linear equations with respectto π1, π2, . . . , π
π, π as follows:
ππ= ππβ
ππ
β
π=0
π½ππ
π
πβ«
1
0
πΎ(π)
π‘(1, π , π) β (π ) ππ , π = 1, . . . , π,
(48)
ππ· = ππ+1
β
π
β
π=1
πππΏπ+1
Ξ¦π(π‘, π) , (49)
where
π· = π·π+1
β
π
β
π=1
π·ππΏπ+1
Ξ¦π(π‘, π) ,
π·π= ππ+1
π
ππ
β
π=0
π½ππβ«
1
0
β (π )πΎ(π)
π‘(1, π , π) ππ , π = 1, π + 1.
(50)
We study the coefficient in (49) for π and the right-handside of this equation as a function of π. Then, with regard to(27), (35), (37), and (38), we obtain
π· = π· + π (π) , (51)
ππ+1
β
π
β
π=1
πππΏπ+1
Ξ¦π(π‘, π)
= ππ+1
β
π
β
π=2
πππΏπ+1
π½πβ1
(π‘)
π½01
+ π (π) .
(52)
From condition (d), π· ΜΈ= 0. Therefore, for sufficiently small π,
π· ΜΈ= 0. (53)
Consequently, for sufficiently small π > 0, (49) is uniquelysolvable and can be represented in the following form:
π = οΏ½ΜοΏ½ (π) =1
π·(ππ+1
β
π
β
π=1
πππΏπ+1
Ξ¦π(π‘, π)) , (54)
and from (51) and (52), the fair estimate for it is
οΏ½ΜοΏ½ (π) = π0+ π (π) , (55)
where
π0=
1
π·
(ππ+1
β
π
β
π=1
πππΏπ+1
π½πβ1
(π‘)
π½01
) . (56)
Now, substituting (54) into (48), we explicitly determine
ππ= ππβ
ππ
β
π=0
π½ππ
οΏ½ΜοΏ½ (π)
πβ«
1
0
πΎ(π)
π‘(1, π , π) β (π ) ππ , π = 1, . . . , π.
(57)
Using (54), (57), and (50) out of (47), we obtain therepresentation, and for the component π¦ of the problemsolutions (1) and (2),
π¦ (π‘, οΏ½ΜοΏ½ (π) , π)
=
π
β
π=1
ππΞ¦π(π‘, π) β οΏ½ΜοΏ½ (π)
Γ
π
β
π=1
(ππ+
ππ
β
π=0
π½ππ
πβ«
1
0
πΎ(π)
π‘(1, π , π) β (π ) ππ )
Γ Ξ¦π(π‘ β π) +
οΏ½ΜοΏ½ (π)
πβ«
π‘
0
πΎ (π‘, π , π) β (π ) ππ .
(58)
Thus, the following theorem is valid.
-
8 Journal of Applied Mathematics
Theorem 8. Let conditions (a)β(d) be satisfied. Then, forsufficiently small π > 0 in a sufficiently small neighborhood ofthe point π = π
0, a unique value of π = οΏ½ΜοΏ½(π) can be determined
such that the pair (π¦(π‘, οΏ½ΜοΏ½(π), π), οΏ½ΜοΏ½(π)) is the unique solution forthe boundary value problems (1) and (2) on the interval [0, 1],where π¦(π‘, οΏ½ΜοΏ½(π), π) is given by formula (58) and οΏ½ΜοΏ½(π) is given byformula (54).
Theorem 9. Let conditions (a)β(e) be satisfied. Then, forsufficiently small π, the solution π¦(π‘, π) of the boundary valueproblems (1) and (2) and its derivatives on the interval 0 β€ π‘ β€1 can be estimated as follows:π¦(π)
(π‘, οΏ½ΜοΏ½ (π) , π)
β€ πΆ[π1β οΏ½ΜοΏ½π1
β (ππ1βπ2 + π
π1βπ exp(βπΎπ‘
π))
+
π
β
π=2
ππβ οΏ½ΜοΏ½ππ
+οΏ½ΜοΏ½max0β€π‘β€1
|β (π‘)| + ππ1βπ
Γ exp(βπΎtπ)(
π
β
π=2
ππβ οΏ½ΜοΏ½ππ
+οΏ½ΜοΏ½max0β€π‘β€1
|β (π‘)|)] ,
π = 0, π β 1,
(59)
where πΆ > 0 and πΎ > 0 are the constants independent of π.
Proof. Formulae (22), (37), and (38) together with (5) implythe following estimates:
πΎ(π)
π‘(π‘, π , π)
β€ πΆπ, π = 0, π β 2, 0 β€ π β€ π‘ β€ 1,
πΎ(πβ1)
π‘(π‘, π , π)
β€ πΆ(π + exp(β
πΎ (π‘ β π )
π)) ,
0 β€ π β€ π‘ β€ 1,
Ξ¦(π)
π(π‘, π)
β€ πΆ β (1 + π
π1βπ β exp(βπΎπ‘
π)) , π = 2, π,
π = 0, π β 1, 0 β€ π‘ β€ 1,
Ξ¦(π)
1(π‘, π)
β€ πΆ (π
π1βπ2 + ππ1βπ β exp(β
πΎπ‘
π)) ,
π = 0, π β 1, 0 β€ π‘ β€ 1.
(60)
By estimating solution (58) and taking into account (60),we obtain (59), which completes the proof of the theorem.
Now, let us formulate the boundary conditions for thefollowing unperturbed (degenerate) equation:
πΏ0π¦ = π΄
1(π‘) π¦(πβ1)
+ β β β + π΄π(π‘) π¦ (π‘) = β (π‘) , (61)
obtained from (1) within π = 0. On the basis ofTheorem 9, wemust conclude that in (58), the coefficient of π
1approaches
zero when π β 0 and the coefficients of ππ, π = 2, π have
the order π(1). Therefore, the boundary conditions for thesolution of the unperturbed (61) are defined with help of theboundary conditions (2), containing π
2, . . . , π
π+1:
πΏ2π¦ + π2π = π2, . . . , πΏ
π+1π¦ + ππ+1
π = ππ+1
. (62)
Next, we show that (61) and boundary conditions (62)actually define the degenerate problem.
By analogy with (17) and (28) for the problems (51)and (52), we introduce the initial function and boundaryfunctions:
πΎ (π‘, π ) =π (π‘, π )
π (π )
, Ξ¦πβ1
(π‘) =π½πβ1
(π‘)
π½01
, π = 2, π (63)
where π½01
is the determinant (6), π½πβ1
(π‘) = π½(0)
πβ1,1(π‘) is the
determinant from Lemma 7, π(π‘, π ) β‘ ππβ1,0
(π‘, π ) is thedeterminant from Lemma 4, and π(π ) β‘ π
π0(π ) is the
Wronskian determinant of the fundamental solution systemπ¦π0(π ), π = 1, π β 1 of homogeneous degenerate equation (13),
which is obtained from π(π ) by replacing the (π β 1)th rowwith the π¦
π0(π‘), π = 1, π β 1 row.
Apparently, πΎ(π‘, π ) is the Cauchy function satisfying thehomogeneous equation πΏ
0πΎ(π‘, π ) = 0 with respect to π‘ and
initial conditions πΎ(π)π‘(π , π ) = 0, π = 0, π β 3, πΎ
(πβ2)
π‘(π , π ) =
1, and Ξ¦π(π‘), π = 1, π β 1 as the boundary functions of the
boundary value problems (61) and (62):
πΏ0Ξ¦π(π‘) = 0, πΏ
πΞ¦π= 1 within π = π + 1,
πΏπΞ¦π= 0 within π ΜΈ= π + 1, π = 2, π.
(64)
Theorem 10. Let conditions (a)β(d) be satisfied.Then, the pair(π¦(π‘, π
0), π0) is the unique solution of the nonhomogeneous
boundary-value problems (61) and (62) on the interval [0, 1],where π
0is expressed by formula (56) and π¦(π‘, π
0) is
π¦ (π‘, π0) =
π
β
π=2
(ππβ π0ππ)Ξ¦πβ1
(π‘)
β π0
π
β
π=2
Ξ¦πβ1
(π‘)
ππ
β
π=0
π½ππβ«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ
+ π0β«
π‘
0
πΎ (π‘, π )
π΄1(π )
β (π ) ππ .
(65)
Proof. We seek the solution (π¦(π‘, π), π) of the boundary valueproblems (61) and (62) in the following form:
π¦ (π‘, π) = π1Ξ¦1(π‘) + β β β + π
πβ1Ξ¦πβ1
(π‘)
+ πβ«
π‘
0
πΎ (π‘, π )
π΄1(π )
β (π ) ππ ,
(66)
where Ξ¦π(π‘), π = 1, π β 1 are boundary functions, πΎ(π‘, π ) is
the Cauchy function, π1, π2, . . . , π
πβ1are unknown constants,
-
Journal of Applied Mathematics 9
and π is the required parameter. It is easy to verify thatthe function π¦(π‘, π) identically satisfies (20). For the deter-mination of π
1, π2, . . . , π
πβ1, π, let us substitute (51) into the
boundary conditions (49).Then, with regard to the boundaryconditions (26), we obtain the following system of linearequations with respect to π
1, π2, . . . , π
πβ1, π:
π1πΏπΞ¦1(π‘) + β β β + π
πβ1πΏπΞ¦πβ1
(π‘)
+ π (ππ+
ππ
β
π=0
π½ππβ«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ ) = ππ,
π = 2, π,
π1πΏπ+1
Ξ¦1(π‘) + β β β + π
πβ1πΏπ+1
Ξ¦πβ1
(π‘)
+ π (ππ+1
+
ππ+1
β
π=0
π½π+1π
β«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ ) = ππ+1
.
(67)
Hence, with regard to (64), we have
ππβ1
= ππβ π (π
π+
ππ
β
π=0
π½ππβ«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ ) , π = 2, π,
(68)π
β
π=2
πππΏπ+1
Ξ¦πβ1
(π‘)
+ π (ππ+1
+
ππ+1
β
π=0
π½π+1π
β«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ )
β π(
π
β
π=2
(ππ+
ππ
β
π=0
π½ππβ«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ )
Γ πΏπ+1
Ξ¦πβ1
(π‘)) = ππ+1
.
(69)
From (53), (58), and condition (d), we determine
π = π0=
1
π·
(ππ+1
β
π
β
π=1
πππΏπ+1
Ξ¦πβ1
(π‘)) , (70)
where π· = π·π+1
β βπ
π=2π·ππΏπ+1
Ξ¦πβ1
ΜΈ= 0, π·π
= ππ+
βππ
π=0π½ππβ«1
0
(β(π )/π΄1(π ))πΎ(π)
π‘(1, π )ππ (π = 1, π + 1), and the
values of π0are given in Section 2.
Substituting (70) into (68), we definitely find
ππβ1
= ππβ π0(ππ+
ππ
β
π=0
π½ππβ«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ ) ,
π = 2, π.
(71)
Now, using (70) and (71) out of (66), we obtain thepresentation (65). The proof of Theorem 10 is complete.
Theorem 11. Let conditions (a)β(e) be satisfied. Then, theestimates
π¦(π)
(π‘, οΏ½ΜοΏ½, π) β π¦(π)
(π‘, π0)β€ πΆ (π + π
π1βπ exp(βπΎ π‘
π)) ,
π‘ β [0, 1] , π = 0, π β 1
(72)
are valid for sufficiently small π > 0, where π¦(π‘, οΏ½ΜοΏ½, π) is thesolution to the problems (1) and (2), and π¦(π‘, π
0) is the solution
of the problems (61) and (62).
Proof. Let π’(π‘, π) = π¦(π‘, οΏ½ΜοΏ½(π), π) β π¦(π‘, π0), where π¦(π‘, οΏ½ΜοΏ½(π), π)
is the solution of the problems (1) and (2) and π¦(π‘, π0) is
the solution of the problems (61) and (62). We substitute thevariable π¦(π‘, οΏ½ΜοΏ½(π), π) = π’(π‘, π) + π¦(π‘, π
0), which represents
the problems (1) and (2) together with (61) and (62) in thefollowing form:
πΏππ’ = βπ β π¦
(π)
(π‘) ,
πΏππ’ =
ππ
β
π=0
πΌπππ’(π)
(0, π) +
ππ
β
π=0
π½πππ’(π)
(1, π) = π (π) ,
π = 2, . . . , π + 1,
πΏ1π’ =
π1
β
π=0
πΌ1ππ’(π)
(0, π) +
π1
β
π=0
π½1ππ’(π)
(1, π)
= π1β π1οΏ½ΜοΏ½ (π) β πΏ
1π¦.
(73)
By applyingTheorem 9 to this problem, we obtain
π’(π)
(π‘, π)β€ πΆ (π + π
π1βπ exp(βπΎπ‘
π)) ,
π‘ β [0, 1] , π = 0, π β 1.
(74)
Now, we obtain the desired estimate (72).The proof of thetheorem is complete.
Thus, from Theorem 11, it follows that the solutionπ¦(π‘, οΏ½ΜοΏ½, π), οΏ½ΜοΏ½ of the boundary value problems (1) and (2)approaches the solution π¦(π‘, π
0), π0of the degenerate prob-
lems (61) and (62) as the small parameter π approaches zero:
limπβ0
οΏ½ΜοΏ½ (π) = π0,
limπβ0
π¦(π)
(π‘, οΏ½ΜοΏ½, π) = π¦(π)
(π‘, π0) , 0 β€ π‘ β€ 1, π = 0,π
1β 1,
limπβ0
π¦(π)
(π‘, οΏ½ΜοΏ½, π) = π¦(π)
(π‘, π0) , 0 < π‘ β€ 1,
π = π1, π1+ 1, . . . , π β 1.
(75)
Therefore, it follows that the problems (61) and (62) aredegenerate problems.
Apparently, passages to the limit (75) are not even in theright neighborhood of the point π‘ = 0. If we specify the
-
10 Journal of Applied Mathematics
solution tendency of the original problems (1) and (2) to thesolution of degenerate problems (61) and (62), we learn thenature of the growth of derivatives of the (1) and (2) problemsolutions in the neighborhood of the point π‘ = 0 for π β 0.For this purpose, we use the representations of (22), (37), and(38) and formulae (58) and (65).Then, for the solution π¦(π‘, π)and its derivatives,π¦(π)(π‘, π), π = 0, 1, . . . , πβ1 of the problems(1) and (2) on the interval 0 β€ π‘ β€ 1, we obtain the followingasymptotic representation:
π¦(π)
(π‘, π) =
π
β
π=2
(ππβ π0ππ)Ξ¦(π)
πβ1(π‘)
β π0
π
β
π=2
Ξ¦(π)
πβ1(π‘)
ππ
β
π=0
π½ππβ«
1
0
πΎ(π)
π‘(1, π )
π΄1(π )
β (π ) ππ
+ π0β«
π‘
0
πΎ(π)
π‘(π‘, π )
π΄1(π )
β (π ) ππ + ππ1βπ
β e(1/π) β«π‘
0π(π₯)ππ₯
β π¦π0(π‘)
πΌ1π1
β ππ
(π‘)
ππ1 (0)β Ξ (π
0)
+ ππβ1βπ
β π0(β
β (π‘) β ππ
(π‘)
ππ (π‘)+ β (0)
β π’π(π‘) β π
π
(π‘)
π’π(0) ππ(0)
β e(1/π) β«π‘
0π(π₯)ππ₯
)
+ π(π + ππ1+1βπe(1/π) β«
π‘
0π(π₯)ππ₯
) .
(76)
Here
Ξ (π0) =
Ξ0(π0)
πΌ1π1
π½01
ΜΈ= 0, (77)
where Ξ0(π0) is the expression (9) from condition (d) as
Ξ0(π0)
=
π
β
π=1
(β1)1+π
π½0π
Γ (ππβ π0ππβ π0
ππ
β
π=0
π½ππβ«
1
0
β (π )
π΄1(π )
πΎ(π)
π‘(1, π ) ππ ) .
(78)
It is easy to say that the representation (78) is expressed inthe following form:
Ξ (π0) =
Ξ0(π0)
πΌ1π1
π½01
=1
πΌ1π1
(π1β π0π1β πΏ1π¦0) ΜΈ= 0. (79)
Now, from (79) and (76), it follows that the derivativesπ¦(πβπ)
(π‘, π), π = 1, . . . , π β π1β 1 at point π‘ = 0 have poles
for π:
π¦(π1+π)
(0, π) =ππ
(0)
ππ(Ξ (π0) + π (π)) ,
π = 1, . . . , π β 1 β π1,
(80)
and π¦(π1)(π‘, π) at the point π‘ = 0 has the phenomenon ofthe π
1th-order initial jump. Moreover, the magnitude of the
jump is defined as
limπβ0
π¦(π1) (0, οΏ½ΜοΏ½, π) β π¦
(π1) (0, π0)
= Ξ (π0) =
1
πΌπ1
(π1β π0π1β πΏ1π¦) .
(81)
Thus, for the parameters π1= fix β {0, 1, . . . , π β 1}, a
class exists for the restoration problem with an initial jumpfrom the position of a singularly perturbed problem.
6. Example, Remarks, and Conclusions
(1) Let us consider the example of the boundary valueproblem exemplifying the problems (1) and (2) as
π β π¦
+ π¦
= π,
π¦ (0, π) = π0+ π, π¦ (1, π) = π
1+ π,
πΌ β π¦ (1, π) + π½π¦
(1, π) = π + ππ.
(82)
Obviously, the considered problems (82) satisfy all therequirements described in Section 2.Then, the solution of theproblems (82) can be represented in the following form:
π¦ (π‘, π) = π β π‘ + π0+ π +
π1β π0
1 β eβ1/πβ
π1β π0
1 β eβ1/πβ eβt/π. (83)
According to (61) and (62), we formulate the degenerateproblem in the following form:
π¦
= π,
π¦ (1) = π1+ π, πΌ β π¦ (1) + π½ β π¦
(1) = π + ππ.
(84)
Then, the pair (π¦(π‘, π0), π0) is the unique solution for the non-
homogeneous boundary value problem (84) on the interval[0, 1], where π
0, π¦(π‘, π
0) are expressed as
π¦ = π0π‘ + π1, π
0=
π β πΌπ1
πΌ + π½ β π. (85)
From (83), it follows that the derivativeπ¦(π‘, π) at the pointπ‘ = 0 has the pole for π:
π¦
(0, π) = π(1
π) . (86)
-
Journal of Applied Mathematics 11
Hence, π¦(π‘, π) at the point π‘ = 0 has the phenomenon of afirst-order initial jump, and above all, the magnitude of theinitial jump is determined as
Ξ = limπβ0
π¦ (0, π) β π¦ (0) = π0+ π0β π1= π0+ π0β πΏ1π¦.
(87)
(2) The cases of π β 1 = π1> π2β₯ β β β β₯ π
π, π β 1 =
π1> ππ, and π = 2, π can be researched in accordance with the
above-represented scheme.(3) We can use the same method for researching the
asymptotics of the solution of the boundary value problemwith a moving boundary:
ππ¦(π)
+ π΄1(π‘) π¦(πβ1)
+ β β β + π΄π(π‘) π¦ = β (π‘) ,
ππ
β
π=0
πΌπππ¦(π)
(0, π) +
ππ
β
π=0
π½πππ¦(π)
(π, π) = ππ, π = 1, . . . , π + 1,
(88)
where π is an unknown function of π.
Conflict of Interests
The author declares that there is no conflict of interestsregarding the publication of this paper.
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