This article investigated a class of switched impulsive fractional control systems with delays occurring at different time instants in both the state and control input. First, we analyzed the state response behavior and established sufficient conditions ensuring the system's stability over a finite time horizon. Next, we demonstrated the system's relative controllability using the fixed-point approach. Finally, a numerical simulation was presented to validate the theoretical findings.
Citation: P. K. Lakshmi Priya, K. Kaliraj, Panumart Sawangtong. Analysis of relative controllability and finite-time stability in nonlinear switched fractional impulsive systems[J]. AIMS Mathematics, 2025, 10(4): 8095-8115. doi: 10.3934/math.2025371
[1] | Jian Cao, José Luis López-Bonilla, Feng Qi . Three identities and a determinantal formula for differences between Bernoulli polynomials and numbers. Electronic Research Archive, 2024, 32(1): 224-240. doi: 10.3934/era.2024011 |
[2] | Mohra Zayed, Gamal Hassan . Kronecker product bases and their applications in approximation theory. Electronic Research Archive, 2025, 33(2): 1070-1092. doi: 10.3934/era.2025048 |
[3] |
Zhi-Wei Sun .
New series for powers of |
[4] | Yaojun Ye, Qianqian Zhu . Existence and nonexistence of global solutions for logarithmic hyperbolic equation. Electronic Research Archive, 2022, 30(3): 1035-1051. doi: 10.3934/era.2022054 |
[5] | Milena Dimova, Natalia Kolkovska, Nikolai Kutev . Global behavior of the solutions to nonlinear Klein-Gordon equation with critical initial energy. Electronic Research Archive, 2020, 28(2): 671-689. doi: 10.3934/era.2020035 |
[6] | Li Wang, Yuanyuan Meng . Generalized polynomial exponential sums and their fourth power mean. Electronic Research Archive, 2023, 31(7): 4313-4323. doi: 10.3934/era.2023220 |
[7] | Chunli Li, Wenchang Chu . Infinite series about harmonic numbers inspired by Ramanujan–like formulae. Electronic Research Archive, 2023, 31(8): 4611-4636. doi: 10.3934/era.2023236 |
[8] | Mahmoud El-Morshedy, Mohamed S. Eliwa, Mohamed El-Dawoody, Hend S. Shahen . A weighted hybrid discrete probability model: Mathematical framework, statistical analysis, estimation techniques, simulation-based ranking, and goodness-of-fit evaluation for over-dispersed data. Electronic Research Archive, 2025, 33(4): 2061-2091. doi: 10.3934/era.2025091 |
[9] | Feida Jiang, Xi Chen, Juhua Shi . Nonexistence of entire positive solutions for conformal Hessian quotient inequalities. Electronic Research Archive, 2021, 29(6): 4075-4086. doi: 10.3934/era.2021072 |
[10] | Shuai Chang, Jinrui Guan . A study on the estimator for the extreme value index of heavy-tailed distribution generated from moment statistic. Electronic Research Archive, 2025, 33(4): 2295-2311. doi: 10.3934/era.2025101 |
This article investigated a class of switched impulsive fractional control systems with delays occurring at different time instants in both the state and control input. First, we analyzed the state response behavior and established sufficient conditions ensuring the system's stability over a finite time horizon. Next, we demonstrated the system's relative controllability using the fixed-point approach. Finally, a numerical simulation was presented to validate the theoretical findings.
In [1,pp. 42 and 55], we find the Maclaurin power series expansions
cosx=∞∑k=0(−1)kx2k(2k)!=1−x22+x424−x6720+x840320−⋯,x∈R |
and
lncosx=−∞∑k=122k−1(22k−1)k(2k)!|B2k|x2k=−x22−x412−x645−17x82520−⋯ | (1) |
for x2<π24, where B2k denotes the Bernoulli numbers which can be generated by
zez−1=∞∑k=0Bkzkk!=1−z2+∞∑k=1B2kz2k(2k)!,|z|<2π. |
Let
F(x)={ln2(1−cosx)x2,0<|x|<2π;0,x=0 | (2) |
and
R(x)={ln2(1−cosx)x2lncosx,0<|x|<π2;16,x=0;0,x=±π2. | (3) |
In the recent paper [2], Li and Qi obtained the following two results:
1. The function F(x) defined by (2) can be expanded into the Maclaurin power series expansion
F(x)=−∞∑n=1E2n(2n)!x2n=−x212−x41440−x690720−x84838400−⋯ | (4) |
for |x|<2π, where
E2n=−|A2n−1,1B2n−1,2n−1ωnC1,2n+1|,n≥1,ωk=(−1)k(k+1)(2k+1),k≥0,A2n−1,1=(0ω10ω2⋮0ωn−10)=(ai,j)1≤i≤2n−1j=1,n≥1,ai,1={0,1≤i=2k−1≤2n−1;ωk,2≤i=2k≤2n−2,B2n−1,2n−1=|(00)ω000⋯00(11)ω00⋯0(20)ω10(22)ω0⋯00(31)ω10⋯0⋮⋮⋮⋱⋮(2n−40)ωn−20(2n−42)ωn−3⋯00(2n−31)ωn−20⋯0(2n−20)ωn−10(2n−22)ωn−1⋯(2n−22n−2)ω0|=(bi,j)1≤i,j≤2n−1,n≥1,bi,j={0,1≤i<j≤2n−1;(ij)ωk,0≤i−j=2k≤2n−2;0,1≤i−j=2k−1≤2n−3,C1,2n−1=(0(2n−11)ωn−10(2n−13)ωn−2⋯0(2n−12n−3)ω10)=(ci,j)i=11≤j≤2n−1,n≥1,c1,j={0,1≤j=2k−1≤2n−1;(2n−12k−1)ωn−k,2≤j=2k≤2n−2. |
2. The function R(x) defined by (3) decreasingly maps [0,π2] onto [0,16].
We now introduce several new even functions as follows:
1. The first function is
F0(x)=lncosx,x∈∞⋃k=0(±2kπ−π2,±2kπ+π2). | (5) |
2. The second function is
F1(x)={ln2(1−cosx)x2,x∈R∖{±2kπ,k=1,2,…};0,x=0. | (6) |
It is clear that F1(x)=F(x) on (−2π,2π).
3. Generally, the third function we are introducing is
Fn(x)={ln((−1)n(2n)!x2n[cosx−n−1∑k=0(−1)kx2k(2k)!]),x≠00,x=0 | (7) |
for n≥2.
Since the double inequality
0<(−1)n[cosx−n−1∑k=0(−1)kx2k(2k)!]<x2n(2n)! | (8) |
is valid for n≥2 and x∈R∖{0}, see [3,p. 326], the function Fn(x) is significantly defined for n≥2 and x∈R.
As a stronger version of the double inequality (8), the following positive, nonnegative, decreasing, and concave properties of the normalized tail
CosRn(x)={(−1)n(2n)!x2n[cosx−n−1∑k=0(−1)kx2k(2k)!],x≠01,x=0 | (9) |
for x∈(0,∞) and n≥1 were discovered in the paper [4]:
(a) the normalized tail CosR1(x) is nonnegative on (0,∞) and is decreasing on [0,2π];
(b) the normalized tail CosRn(x) for n≥2 is decreasing and positive on (0,∞);
(c) the normalized tail CosR1(x) is concave on (0,x0), where x0∈(π2,π) is the first positive zero of the equation
(x2−2)sinx+2xcosx=0 |
and the normalized remainder CosRn(x) for n≥2 is concave on (0,π).
Comparing the definition in (9) with those in (6) and (7) leads to the following conclusions:
(a) the function F1(x) is decreasing and negative on (0,2π), and is concave on (0,x0);
(b) the function Fn(x) for n≥2 is decreasing and negative on (0,∞), and is concave on (0,π).
4. The fourth function Rm,n(x) for n>m≥0 is defined
(a) when n>m=0, by
R0,n(x)={Fn(x)F0(x),0<|x|<π2;1(n+1)(2n+1),x=0;0,x=±π2, | (10) |
(b) when n>m=1, by
R1,n(x)={Fn(x)F1(x),x∈R∖{±2kπ,k=1,2,…};6(n+1)(2n+1),x=0;0,x∈{±2kπ,k=1,2,…}, |
(c) when n>m≥2, by
Rm,n(x)={Fn(x)Fm(x),x≠0;(m+1)(2m+1)(n+1)(2n+1),x=0. |
It is easy to see that R0,1(x)=R(x).
We now propose the following three problems:
1. Is the function Fn(x) for n≥0 decreasing and concave?
2. What is the Maclaurin power series expansion of Fn(x) for n≥0 around the origin x=0?
3. Is the function Rm,n(x) for n>m≥0 decreasing?
The first problem for the case n=0 is immediate: the even function F0(x)=lncosx is decreasing and, by virtue of the series expansion (1), is concave in x∈(0,π2). The first problem for the case n≥1 was solved in the paper [4], as mentioned above. In a word, the first problem has been thoroughly solved.
The second problem for n=0 is just the Maclaurin power series expansion (1). The second problem for n=1 was solved by the Maclaurin series expansion (4), which was established in [2,Section 3].
The third problem for (m,n)=(0,1) was solved in [2,Section 4], as mentioned above.
In this paper, we will give a full answer to the second problem for all cases n≥2, solve the first problem on the interval (0,π2) once again, and discuss the third problem for the case n≥2.
In this section, we solve the second problem: what is the Maclaurin power series expansion of Fn(x) for n≥0 around the origin x=0?
Theorem 1. For n≥0, let
ei,j(n)={(−1)i/21+(−1)i21(2n+i2n),1≤i≤2m,j=1(−1)(i−j+1)/21+(−1)i−j+12(i−1j−2)(2n+i−j+12n),1≤i≤2m,2≤j≤2m |
and
D2m(n)=|ei,j(n)|(2m)×(2m). |
Then the even function Fn(x) for n≥0 can be expanded into
Fn(x)=−∞∑m=1D2m(n)(2m)!x2m,|x|<{π2,n=0;2π,n=1;∞,n≥2. | (11) |
Proof. Let u(x) and v(x)≠0 be two n-time differentiable functions on an interval I for a given integer n≥0. Then the nth derivative of the ratio u(x)v(x) is
dndxn[u(x)v(x)]=(−1)n|W(n+1)×(n+1)(x)|vn+1(x),n≥0, | (12) |
where the matrix
W(n+1)×(n+1)(x)=(U(n+1)×1(x)V(n+1)×n(x))(n+1)×(n+1), |
the matrix U(n+1)×1(x) is an (n+1)×1 matrix whose elements satisfy uk,1(x)=u(k−1)(x) for 1≤k≤n+1, the matrix V(n+1)×n(x) is an (n+1)×n matrix whose elements are vℓ,j(x)=(ℓ−1j−1)v(ℓ−j)(x) for 1≤ℓ≤n+1 and 1≤j≤n, and the notation |W(n+1)×(n+1)(x)| denotes the determinant of the (n+1)×(n+1) matrix W(n+1)×(n+1)(x). This is a slight reformulation of [5,p. 40,Exercise 5].
Let
un(x)=∞∑k=0(−1)k+1(2k+2n+22n)x2k+1(2k+1)!andvn(x)=∞∑k=0(−1)k(2k+2n2n)x2k(2k)!. |
Then, straightforward differentiation yields
u(2ℓ+1)n(0)=limx→0∞∑k=0(−1)k+1(2k+2n+22n)⟨2k+1⟩2ℓ+1x2k−2ℓ(2k+1)!=(−1)ℓ+1(2ℓ+2n+22n),v(2ℓ)n(0)=limx→0∞∑k=0(−1)k(2k+2n2n)⟨2k⟩2ℓx2k−2ℓ(2k)!=(−1)ℓ(2ℓ+2n2n),u(2ℓ)n(0)=0,v(2ℓ+1)n(0)=0 |
for ℓ≥0. Considering Expression (14) and applying the derivative formula (12) for the ratio of two differentiable functions, we acquire
F(2m)n(0)=limx→0[∞∑k=0(−1)k+1(2k+2n+22n)x2k+1(2k+1)!∞∑k=0(−1)k(2k+2n2n)x2k(2k)!](2m−1)=limx→0[un(x)vn(x)](2m−1)=(−1)2m−1v2mn(0)|un(0)vn(0)0⋯0u′n(0)v′n(0)(11)vn(0)⋯0u″n(0)v″n(0)(21)v′n(0)⋯0u(3)n(0)v(3)n(0)(31)v″n(0)⋯0u(4)n(0)v(4)n(0)(41)v(3)n(0)⋯0⋮⋮⋮⋱⋮u(2m−1)n(0)v(2m−1)n(0)(2m−11)v(2m−2)n(0)⋯(2m−12m−2)v′n(0)|=−|0(00)000−1(2n+22n)0(11)000−(20)(2n+22n)0(22)01(2n+42n)0−(31)(2n+22n)0(33)0(40)(2n+42n)0−(42)(2n+22n)0⋮⋮⋮⋮⋮(−1)m−1(2n+2m−22n)0(−1)m−2(2m−31)(2n+2m−42n)0(−1)m−3(2m−33)(2n+2m−62n)0(−1)m−1(2m−20)(2n+2m−22n)0(−1)m−2(2m−22)(2n+2m−42n)0(−1)m(2n+2m2n)0(−1)m−1(2m−11)(2n+2m−22n)0(−1)m−2(2m−13)(2n+2m−42n)⋯000000⋯000000⋯000000⋯000000⋯000000⋱⋮⋮⋮⋮⋮⋮⋯(2m−32m−7)(2n+42n)0−(2m−32m−5)(2n+22n)0(2m−32m−3)0⋯0(2m−22m−6)(2n+42n)0−(2m−22m−4)(2n+22n)0(2m−22m−2)⋯−(2m−12m−7)(2n+62n)0(2m−12m−5)(2n+42n)0−(2m−12m−3)(2n+22n)0| |
for m≥1. In other words, for m≥1,
F(2m)n(0)=−D2m(n)=−|ei,j(n)|(2m)×(2m). |
Consequently, the even function Fn(x) can be expanded into
Fn(x)=∞∑k=0F(k)nxkk!=∞∑m=1F(2m)nx2m(2m)!=−∞∑m=1D2m(n)(2m)!x2m. |
The proof of Theorem 1 is completed.
Remark 1. When n=0, a direct computation gives
D4(0)=|0(00)00−10(11)00−(20)0(22)10−(31)0|=2andD2(0)=|0(00)−10|=1. |
Then, the first two terms of the Maclaurin power series expansion of the function lncosx are
−D2(0)2!x2−D4(0)4!x4=−12!x2−24!x4=−12x2−112x4, |
which coincide with the first two terms in the series expansion (1).
When n=1, straightforward computation shows
D4(1)=|0(00)00−1(42)0(11)00−(20)(42)0(22)1(62)0−(31)(42)0|=160andD2(1)=|0(00)−1(42)0|=16. |
Then, the first two terms of the Maclaurin power series expansion of the function F(x) defined by (2) are
−D2(1)2!x2−D4(1)4!x4=−112x2−11440x4, |
which coincide with the first two terms in the series expansion (4).
Remark 2. Comparing the Maclaurin series expansions (1) and (4) with the series expansion (11) reveals
|B2m|=m22m−1(22m−1)D2m(0)andE2m=D2m(1) | (13) |
for m≥1. The first formula in (13) is a new determinantal expression for the Bernoulli numbers B2m with m≥1.
Additionally, we point out that, in the papers [2,6,7,8,9,10], there have been many related results, but different from and more complicated than the first one in (13), and plenty of closely-related references on closed-form formulas and determinantal expressions for the Bernoulli numbers and polynomials B2m and Bm(x) with m∈N.
In this section, we give an alternative and united proof of a modification of the first problem: is the function Fn(x) for n≥0 decreasing and concave on (0,π2)?
Theorem 2. For n=0 and n≥2, the even function Fn(x) defined by (5) and (7) is decreasing and concave on (0,π2). The even function F1(x) defined in (6) is decreasing on (0,2π) and (xk,2(k+1)π) for k∈N, while it is increasing on (2kπ,xk) for k∈N, where xk∈(2kπ,2(k+1)π) for k∈N is the zero of the equation tanx2=x2 on (0,∞).
Proof. In the first section of this paper, it has been immediately verified that the function F0(x)=lncosx is decreasing and concave on (0,π2).
The derivative of F1(x) can be written as
F′1(x)=1tanx2−1x2,x≠±2kπ,k∈N. |
Therefore, the derivative F′1(x) is negative on (0,2π), is positive on (2kπ,xk), and is negative on (xk,2(k+1)π) for k∈N, where xk∈(2kπ,2(k+1)π) for k∈N is the zero of the equation tanx2=x2 on (0,∞). Accordingly, the function F1(x) is decreasing on (0,2π) and (xk,2(k+1)π), while it is increasing on (2kπ,xk) for k∈N.
On the interval (0,π2) and for n≥2, the function Fn(x) can be written as
Fn(x)=ln∞∑k=n(−1)k−n(2n)!(2k)!x2k−2n=ln∞∑k=0(−1)k(2k+2n2n)x2k(2k)!. |
Its first derivative is
F′n(x)=∞∑k=0(−1)k+1(2k+2n+22n)x2k+1(2k+1)!∞∑k=0(−1)k(2k+2n2n)x2k(2k)!. | (14) |
By virtue of [11,Theorem 7.6], or in view of the results at the site https://math.stackexchange.com/a/477549 (accessed on 18 January 2024), we derive the integral representation
cosx−n−1∑k=0(−1)kx2k(2k)!=(−1)nx2n∞∑k=0(−1)k(2n+2k)!x2k=(−1)n(2n−2)!∫x0(x−t)2n−2sintdt | (15) |
for n≥1 and x∈R. From the integral representation (15), it follows that
(−1)n(2n)!x2n[cosx−n−1∑k=0(−1)k(2k)!x2k]=∞∑k=0(−1)k(2k+2n2n)x2k(2k)!=2n(2n−1)x2n∫x0(x−t)2n−2sintdt=2n(2n−1)∫10(1−u)2n−2sin(ux)xdu>0,0<x<π | (16) |
and
[∞∑k=0(−1)k(2k+2n2n)x2k(2k)!]′=∞∑k=0(−1)k+1(2k+2n+22n)x2k+1(2k+1)!=2n(2n−1)∫10(1−u)2n−2ddx[sin(ux)x]du=2n(2n−1)∫10(1−u)2n−2cos(ux)(ux)−tan(ux)x2du<0,0<x<π2 |
for n≥1, where we used the inequalities cosx>0 and x−tanx<0 in x∈(0,π2). This means that
F′n(x)=∫10(1−u)2n−2cos(ux)(ux)−tan(ux)x2du∫10(1−u)2n−2sin(ux)xdu<0,0<x<π2 |
for n≥1. In conclusion, the function Fn(x) for n≥1 is decreasing on (0,π2).
It is known that
sinxx=∞∑k=0(−1)kx2k(2k+1)!,|x|<∞. |
Straightforward differentiating and simplifying give
(sinxx)″=∞∑k=0(−1)k+1(2k+2)(2k+1)(2k+3)!x2k=−∞∑k=0(4k+4)(4k+3)(4k+5)![(4k+1)(4k+2)(4k+5)(4k+3)−x2]x4k<0,x∈(0,√103)⊃(0,π2]. |
Therefore, a direct differentiation and simplification yield
F″n(x)=[∫10(1−u)2n−2ddx(sin(ux)x)du∫10(1−u)2n−2sin(ux)xdu]′=−1[∫10(1−u)2n−2sin(ux)xdu]2[(∫10(1−u)2n−2ddx(sin(ux)x)du)2−∫10(1−u)2n−2d2dx2(sin(ux)x)du∫10(1−u)2n−2sin(ux)xdu]=−1[∫10(1−u)2n−2sin(ux)xdu]2[(∫10u(1−u)2n−2ddx(sin(ux)ux)du)2−∫10u(1−u)2n−2d2dx2(sin(ux)ux)du∫10u(1−u)2n−2sin(ux)uxdu]<0 |
on (0,π2) for n≥1. Accordingly, the function Fn(x) for n≥1 is concave on (0,π2). The proof of Theorem 2 is thus complete.
Remark 3. We note that a concave function must be a logarithmically concave function, but the converse is not true. However, a logarithmically convex function must be a convex function, but the converse is not true.
In [2,Section 4], the function R0,1(x)=R(x) defined by (3) or (10) for n=1 was proved to be decreasing on [0,π2] onto [0,16].
Theorem 3. The even function R0,2(x) defined by (10) for the case n=2 is decreasing on [0,π2].
Proof. For n≥2, direct differentiation gives
F′n(x)F′0(x)=[lnCosRn(x)]′(lncosx)′=−CosR′n(x)CosRn(x)cosxsinx |
and
[F′n(x)F′0(x)]′=−[CosR′n(x)CosRn(x)cosxsinx]′=−(CosRn(x)CosR″n(x)−[CosR′n(x)]2)cosxsinx−CosRn(x)CosR′n(x)[CosRn(x)sinx]2. |
Taking n=2 and simplifying lead to
[F′2(x)F′0(x)]′=−72x10[CosR2(x)sinx]2[4x(x4−6x2+12)+4(7x2−16)xcosx+16xcos(2x)−4x3cos(3x)+(3x4+4x2−16)sinx+2(x4−10x2+12)sin(2x)−(x2−2x−4)(x2+2x−4)sin(3x)+4sin(4x)]=−72x10[CosR2(x)sinx]2∞∑k=6(−1)kQ(k)x2k+1(2k+1)!=−72x10[CosR2(x)sinx]2∞∑k=3[Q(2k)Q(2k+1)(4k+3)!(4k+1)!−x2]Q(2k+1)(4k+3)!x4k+1, |
where
Q(k)=42k+2−4(4k4−28k3+107k2+61k+324)32k−3+(4k4−4k3+39k2+53k+64)22k+4(12k4−68k3−7k2−17k−20),k≥6. |
From the facts that
12k4−68k3−7k2−17k−20=12(k−6)4+220(k−6)3+1361(k−6)2+2923(k−6)+490≥490,k≥6,4k4−4k3+39k2+53k+64=4(k−6)4+92(k−6)3+822(k−6)2+3437(k−6)+5782≥5782,k≥6, |
and, by induction,
42k+2−4(4k4−28k3+107k2+61k+324)32k−3=16×32k[(43)2k−4k4−28k3+107k2+61k+324108]>0,k≥7, |
we conclude, together with Q(6)=3871296, that Q(k)≥3871296 for k≥6.
Let
Q(k)=Q(2k)Q(2k+1)(4k+3)!(4k+1)!,k≥3. |
The inequality
Q(k+1)>Q(k),k≥3 |
is equivalent to
(2k+3)(4k+7)Q(2k+1)Q(2k+2)>(2k+1)(4k+3)Q(2k)Q(2k+3) |
for k≥3, that is,
Q(k)=216[73728(k−2)9+1508352(k−2)8+13174784(k−2)7+63787136(k−2)6+185680928(k−2)5+329304964(k−2)4+345900612(k−2)3+210339955(k−2)2+94117995(k−2)+42704050]+27×24k{(142293×24k+9+93239336)k5+4(228963×24k+7−315163)k4+(1730269×24k+5−77141534)k3+(590587×24k+5−61162271)k2+31(39633×24k+3−705961)k+72(32581×16k−50315)+4096(57×24k+3+847)k8+2048(24k+7−540k−1635)k9+32k6[24k+6(3328k−3377)+1151464k+2801469]}+27×212k+7[256k(24k+5−45k5)+9×24k+10+12352k5+24016k4+33804k3+78984k2+84261k+33915]+16×34k[159784960(k−4)9+2908177408(k−4)8+31203008512(k−4)7+218332899456(k−4)6+1039043941024(k−4)5+3394763402820(k−4)4+7477586709444(k−4)3+10528669786283(k−4)2+8416641010791(k−4)+2806689073644]+8×38k+3(8192k9+9216k8+30720k7+148608k6+179232k5+77220k4+1027780k3+2247363k2+1992375k+751032)+64k[107481088(k−4)9+1948553216(k−4)8+20892092672(k−4)7+146632542496(k−4)6+702801488840(k−4)5+2321298590084(k−4)4+5179870312810(k−4)3+7367488384493(k−4)2+5849176490661(k−4)+1817172122508]+28k+334k[313600(k−13)6+20524992(k−13)5+540906544(k−13)4+7219464756(k−13)3+49643220604(k−13)2+151463526603(k−13)+98734469508]>0,k≥3. |
By virtue of the above expression for Q(k), we see that the sequence Q(k) is positive for k≥13. On the other hand, it is straightforward that
Q(3)=352780960860822574080,Q(4)=249398534923066892200578048,Q(5)=61305423558540152150473900185600,Q(6)=8665426549135034591879376586377676800,Q(7)=896760345938903204692495757195177830886400,Q(8)=77679040214402381392287613848479095562672133120,Q(9)=6092826722565745296376115137707251410869680486780928,Q(10)=453017430243005416828735039714559150312936188925226332160,Q(11)=32749134150707011053456859834163170645192635726524315359872000,Q(12)=2332073744679555396812875864144181190554219273032749874293655526400. |
Consequently, the sequence Q(k) is positive for all k≥3. As a result, the sequence Q(k) is increasing in k≥3. It is immediate that Q(3)=423115=3.678…. Hence, we acquire
Q(k)≥423115=3.678…,k≥3. |
Accordingly, when
0<x≤π2=1.570⋯<√423115=3.678⋯, |
the derivative [F′2(x)F′0(x)]′ is negative, and then the derivative ratio F′2(x)F′0(x) is decreasing in x∈(0,π2].
In [12,pp. 10-11,Theorem 1.25], a monotonicity rule for the ratio of two functions was established as follows.
For a,b∈R with a<b, let p(x) and q(x) be continuous on [a,b], differentiable on (a,b), and q′(x)≠0 on (a,b). If the ratio p′(x)q′(x) is increasing on (a,b), then both p(x)−p(a)q(x)−q(a) and p(x)−p(b)q(x)−q(b) are increasing in x∈(a,b).
With the help of this monotonicity rule and in view of the decreasing property of the derivative ratio F′2(x)F′0(x) in x∈(0,π2], we derive that the ratio F2(x)F0(x)=R0,2(x) is decreasing in x∈(0,π2]. The required proof of Theorem 3 is completed.
Remark 4. How to verify the decreasing property of the function R0,n(x) for n≥3 on (0,π2], of the function R1,n(x) on (0,2π), and of the function Rm,n(x) for n>m≥2 on (0,∞)? The ideas, approaches, techniques, and methods used in the proof of Theorem 3 should not be valid again, so we need to discover new ideas, approaches, techniques, and methods for verifying the decreasing property mentioned above.
Remark 5. Let
fα(x)=∫10(1−u)αcos(ux)du,α∈R. |
Prove that the function fα(x) is positive in x∈(0,∞) if and only if α>1, while it is decreasing in x∈(0,∞) if and only if α≥2.
This paper and the articles [2,13,14] are siblings, because some results in [2] have been generalized in this paper, and the results in [13,14] are about the Maclaurin power series expansions of logarithmic expressions involving normalized tails of the tangent and sine functions.
In this paper, we presented the following results.
1. The function Fn(x) for n≥0 was expanded into the Maclaurin power series expansion (11) in Theorem 1.
2. The function Fn(x) defined by (7) for n≥0 was proved in Theorem 2 to be decreasing and concave on (0,π2).
3. A new determinantal expression (13) of the Bernoulli numbers B2m for m≥1 was derived.
4. The ratio R0,2(x) was proved in Theorem 3 to be decreasing in x∈[0,π2].
In order to verify the decreasing property of the function R0,n(x) for n≥3 on (0,π2), of the function R1,n(x) on (0,2π), and of the function Rm,n(x) for n>m≥2 on (0,∞), we need new ideas, novel approaches, creative techniques, and innovative methods.
The authors declare they have not used Artificial Intelligence (AI) tools in the creation of this article.
This work was supported in part by the National Natural Science Foundation of China (Grant No. 12061033).
The authors declare there is no conflicts of interest.
[1] |
Z. Ai, L. Peng, Stabilization and robustness analysis of multi-module impulsive switched linear systems, Nonlinear Anal. Hybrid Syst., 30 (2018), 293–305. https://doi.org/10.1016/j.nahs.2018.06.001 doi: 10.1016/j.nahs.2018.06.001
![]() |
[2] |
V. D. Blondel, J. N. Tsitsiklis, Complexity of stability and controllability of elementary hybrid systems, Automatica, 35 (1999), 479–489. https://doi.org/10.1016/S0005-1098(98)00175-7 doi: 10.1016/S0005-1098(98)00175-7
![]() |
[3] |
C. Possieri, A. R. Teel, Structural properties of a class of linear hybrid systems and output feedback stabilization, IEEE Trans. Automat. Control, 62 (2017), 2704–2719. https://doi.org/10.1109/TAC.2016.2617090 doi: 10.1109/TAC.2016.2617090
![]() |
[4] |
Y. Shu, B. Li, Existence and uniqueness of solutions to uncertain fractional switched systems with an uncertain stock model, Chaos Solitons Fract., 155 (2022), 111746. https://doi.org/10.1016/j.chaos.2021.111746 doi: 10.1016/j.chaos.2021.111746
![]() |
[5] |
Z. Lv, B. Chen, Existence and uniqueness of positive solutions for a fractional switched system, Abstr. Appl. Anal., 2014 (2014), 828721. https://doi.org/10.1155/2014/828721 doi: 10.1155/2014/828721
![]() |
[6] |
Y. Q. Guan, L. Wang, Target controllability of multi-agent systems under fixed and switching topologies, Internat. J. Robust Nonlinear Control, 29 (2023), 2725–2741. https://doi.org/10.1002/rnc.4518 doi: 10.1002/rnc.4518
![]() |
[7] |
L. He, S. Banihashemi, H. Jafari, A. Babaei, Numerical treatment of a fractional order system of nonlinear stochastic delay differential equations using a computational scheme, Chaos Solitons Fract., 149 (2021), 111018. https://doi.org/10.1016/j.chaos.2021.111018 doi: 10.1016/j.chaos.2021.111018
![]() |
[8] |
V. S. Muni, R. K. George, Controllability of semilinear impulsive control systems with multiple delays in control, IMA J. Math. Control Inform., 36 (2019), 869–899. https://doi.org/10.1093/imamci/dny011 doi: 10.1093/imamci/dny011
![]() |
[9] |
T. Mur, H. R. Henriquez, Relative controllability of linear systems of fractional order with delay, Math. Control Related Fields, 5 (2015), 845–858. https://doi.org/10.3934/mcrf.2015.5.845 doi: 10.3934/mcrf.2015.5.845
![]() |
[10] |
M. Feˇckan, Y. Zhou, J. R. Wang, On the concept and existence of solution for impulsive fractional differential equations, Commun. Nonlinear Sci. Numer. Simul., 17 (2012), 3050–3060. https://doi.org/10.1016/j.cnsns.2011.11.017 doi: 10.1016/j.cnsns.2011.11.017
![]() |
[11] |
X. Zhang, C. Li, T. Huang, Impacts of state-dependent impulses on the stability of switching Cohen-Grossberg neural networks, Adv. Differ. Equ., 2017 (2017), 316. https://doi.org/10.1186/s13662-017-1375-z doi: 10.1186/s13662-017-1375-z
![]() |
[12] |
Z. L. You, J. R. Wang, Stability of impulsive delay differential equations, J. Appl. Math. Comput., 56 (2018), 253–268. https://doi.org/10.1007/s12190-016-1072-1 doi: 10.1007/s12190-016-1072-1
![]() |
[13] |
Z. L. You, J. R. Wang, On the exponential stability of nonlinear delay system with impulses, IMA J. Math. Control Inform., 35 (2018), 773–803. https://doi.org/10.1093/imamci/dnw077 doi: 10.1093/imamci/dnw077
![]() |
[14] |
K. Balachandran, Y. Zhou, J. Kokila, Relative controllability of fractional dynamical systems with multiple delays in control, Comput. Math. Appl., 64 (2012), 3201–3209. https://doi.org/10.1016/j.camwa.2011.11.061. doi: 10.1016/j.camwa.2011.11.061
![]() |
[15] |
J. Huang, X. Ma, H. Che, Z. Han, Further results on interval observer design for discrete-time switched systems and application to circuit systems, IEEE Trans. Circuits Syst. II. Express Briefs, 67 (2020), 2542–2546. https://doi.org/10.1109/TCSII.2019.2957945 doi: 10.1109/TCSII.2019.2957945
![]() |
[16] |
H. P. Luo, S. Liu, Relative controllability of nonlinear switched fractional delayed systems, Commun. Nonlinear Sci. Numer. Simul., 119 (2023), 107133. https://doi.org/10.1016/j.cnsns.2023.107133 doi: 10.1016/j.cnsns.2023.107133
![]() |
[17] |
M. Pospisil, Relative of controllability of neutral differential equations with a delay, SIAM J. Control Optim., 55 (2017), 835–855. https://doi.org/10.1137/15M1024287 doi: 10.1137/15M1024287
![]() |
[18] |
S. Zhao, Z. Zhang, T. Wang, W. Yu, Controllability for a class of time-varying controlled switching impulsive systems with time delays, Appl. Math. Comput., 228 (2014), 404–410. https://doi.org/10.1016/j.amc.2013.11.103 doi: 10.1016/j.amc.2013.11.103
![]() |
[19] |
S. Zhao, J. Sun, A geometric approach for reachability and observability of linear switched impulsive systems, Nonlinear Anal., 72 (2010), 4221–4229. https://doi.org/10.1016/j.na.2010.01.052 doi: 10.1016/j.na.2010.01.052
![]() |
[20] |
D. X. Zhang, J. Y. Yan, B. Hu, Z. H. Guan, D. F. Zheng, Controllability on a class of switched time-varying systems with impulses and multiple time delays, Internat. J. Systems Sci., 53 (2022), 2261–2280. https://doi.org/10.1080/00207721.2022.2050436 doi: 10.1080/00207721.2022.2050436
![]() |
[21] |
H. P. Luo, S. Liu, X. W. Zhao, T. Huang, Relative controllability of nonlinear switched fractional systems, Asian J. Control, 26 (2023), 312–322. https://doi.org/10.1002/asjc.3205 doi: 10.1002/asjc.3205
![]() |
[22] |
H. P. Luo, S. Liu, Relative controllability of nonlinear switched fractional delayed systems, Commun. Nonlinear Sci. Numer. Simul., 119 (2023), 107133. https://doi.org/10.1016/j.cnsns.2023.107133 doi: 10.1016/j.cnsns.2023.107133
![]() |
[23] |
T. Kacorek, Stability of positive fractional switched continuous-time linear systems, Bull. Pol. Acad. Sci., 61 (2013), 349–352. https://doi.org/10.2478/bpasts-2013-0033 doi: 10.2478/bpasts-2013-0033
![]() |
[24] |
L. Xu, B. Bao, H. Hu, Stability of impulsive delayed switched systems with conformable fractional-order derivatives, Internat. J. Systems Sci., 56 (2025), 1271–1288. https://doi.org/10.1080/00207721.2024.2421454 doi: 10.1080/00207721.2024.2421454
![]() |
[25] |
J. Liang, B. Wu, L. Liu, Y. Wang, C. Li, Finite-time stability and finite-time boundedness of fractional order switched systems, Trans. Inst. Meas. Control, 41 (2015), 3364–3371. https://doi.org/10.1177/0142331219826333 doi: 10.1177/0142331219826333
![]() |
[26] |
V. Kumar, M. Kostic, A. Tridane, A. Debbouche, Controllability of switched Hilfer neutral fractional dynamic systems with impulses, IMA J. Math. Control Inform., 39 (2022), 807–836. https://doi.org/10.1093/imamci/dnac011 doi: 10.1093/imamci/dnac011
![]() |
[27] |
J. R. Wang, M. Fe˜ckan, Y. Zhou, Fractional order differential switched systems with coupled nonlocal initial and impulsive conditions, Bull. Sci. Math., 141 (2017), 727–746. https://doi.org/10.1016/j.bulsci.2017.07.007 doi: 10.1016/j.bulsci.2017.07.007
![]() |
[28] |
A. B. Makhlouf, D. Baleanu, Finite time stability of fractional order systems of neutral type, Fractal Fract., 6 (2022), 289. https://doi.org/10.3390/fractalfract6060289 doi: 10.3390/fractalfract6060289
![]() |
[29] |
A. Zada, B. Pervaiz, M. Subramanian, I. L. Popa, Finite time stability for nonsingular impulsive first order delay differential systems, Appl. Math. Comput., 421 (2022), 126943. https://doi.org/10.1016/j.amc.2022.126943 doi: 10.1016/j.amc.2022.126943
![]() |
[30] |
T. Feng, L. Guo, B. Wu, Y. Q. Chen, Stability analysis of switched fractional-order continuous-time systems, Nonlinear Dyn., 102 (2020), 2467–2478. https://doi.org/10.1007/s11071-020-06074-8 doi: 10.1007/s11071-020-06074-8
![]() |
[31] |
J. Huang, D. Luo, Relatively exact controllability of fractional stochatic delay system driven by L˜evy noise, Math. Methods Appl. Sci., 46 (2023), 11188–11211. https://doi.org/10.1002/mma.9175 doi: 10.1002/mma.9175
![]() |
[32] |
A. M. Elshenhab, X. T. Wang, F. Mofarreh, O. Bazighifan, Exact solutions and finite time stability of linear conformable fractional systems with pure delay, Comput. Modell. Eng. Sci., 134 (2022), 927–940. https://doi.org/10.32604/cmes.2022.021512 doi: 10.32604/cmes.2022.021512
![]() |
[33] |
A. M. Elshenhab, X. T. Wang, Representation of solutions for linear fractional systems with pure delay and multiple delays, Math. Methods Appl. Sci., 44 (2021), 12835–12850. https://doi.org/10.1002/mma.7585 doi: 10.1002/mma.7585
![]() |
[34] |
J. Cermˊak, J. Horni˜cek, T. Kisela, Stability regions for fractional differential systems with a time delay, Commun. Nonlinear Sci. Numer. Simul., 31 (2016), 108–123. https://doi.org/10.1016/j.cnsns.2015.07.008 doi: 10.1016/j.cnsns.2015.07.008
![]() |
[35] |
V. Kumar, M. Malik, D. Baleanu, Results on Hilfer fractional switched dynamical systems with non-instantaneous impulses, Paramana J. Phys., 96 (2022), 172. https://doi.org/10.1007/s12043-022-02411-1 doi: 10.1007/s12043-022-02411-1
![]() |
[36] |
X. Liu, S. Zhong, X. Ding, Robust exponential stability of impulsive switched systems with switching delays: A Razumikhin approach, Commun. Nonlinear Sci. Numer. Simul., 17 (2012), 1805–1812. https://doi.org/10.1016/j.cnsns.2011.09.013 doi: 10.1016/j.cnsns.2011.09.013
![]() |
[37] |
Q. Meng, H. Yang, B. Jiang, Small-time local controllability of switched nonlinear systems, IEEE Trans. Automat. Control, 66 (2021), 5422–5428. https://doi.org/10.1109/TAC.2020.3044898 doi: 10.1109/TAC.2020.3044898
![]() |
[38] |
W. Ren, J. Xiong, Stability analysis of stochastic impulsive switched systems with deterministic state-dependent impulses and switches, SIAM J. Control Optim., 59 (2021), 2068–2092. https://doi.org/10.1137/20M1353460 doi: 10.1137/20M1353460
![]() |
[39] |
J. Yan, B. Hu, Z. H. Guan, Controllability of nonlinear impulsive and switching systems with input delay, IEEE Trans. Automat. Control, 68 (2023), 1184–1191. https://doi.org/10.1109/TAC.2022.3149876 doi: 10.1109/TAC.2022.3149876
![]() |
[40] |
M. Li, J. Wang, Exploring delayed Mittag-Leffler type matrix functions to study finite time stability of fractional delay differential equations, Appl. Math. Comput., 324 (2018), 254–265. https://doi.org/10.1016/j.amc.2017.11.063 doi: 10.1016/j.amc.2017.11.063
![]() |
[41] |
H. Ye, J. Gao, Y. Ding, A generalized gronwall inequality and its application to a fractional differential equation, J. Math. Anal. Appl., 328 (2007), 1075–1081. https://doi.org/10.1016/j.jmaa.2006.05.061 doi: 10.1016/j.jmaa.2006.05.061
![]() |
[42] | D. R. Smart, Fixed point theorems, Cambridge University Press, 1974. |
1. | Zhi-Hua Bao, Ravi Prakash Agarwal, Feng Qi, Wei-Shih Du, Some Properties on Normalized Tails of Maclaurin Power Series Expansion of Exponential Function, 2024, 16, 2073-8994, 989, 10.3390/sym16080989 | |
2. | Yue-Wu Li, Feng Qi, A New Closed-Form Formula of the Gauss Hypergeometric Function at Specific Arguments, 2024, 13, 2075-1680, 317, 10.3390/axioms13050317 | |
3. | Feng Qi, Absolute Monotonicity of Normalized Tail of Power Series Expansion of Exponential Function, 2024, 12, 2227-7390, 2859, 10.3390/math12182859 | |
4. | Da-Wei Niu, Feng Qi, Monotonicity Results of Ratios between Normalized Tails of Maclaurin Power Series Expansions of Sine and Cosine, 2024, 12, 2227-7390, 1781, 10.3390/math12121781 | |
5. | Tao Zhang, Zhen-Hang Yang, Feng Qi, Wei-Shih Du, Some Properties of Normalized Tails of Maclaurin Power Series Expansions of Sine and Cosine, 2024, 8, 2504-3110, 257, 10.3390/fractalfract8050257 | |
6. | Wei-Juan Pei, Bai-Ni Guo, Monotonicity, convexity, and Maclaurin series expansion of Qi's normalized remainder of Maclaurin series expansion with relation to cosine, 2024, 22, 2391-5455, 10.1515/math-2024-0095 | |
7. | Hong-Chao Zhang, Bai-Ni Guo, Wei-Shih Du, On Qi’s Normalized Remainder of Maclaurin Power Series Expansion of Logarithm of Secant Function, 2024, 13, 2075-1680, 860, 10.3390/axioms13120860 | |
8. | Feng Qi, Series and Connections Among Central Factorial Numbers, Stirling Numbers, Inverse of Vandermonde Matrix, and Normalized Remainders of Maclaurin Series Expansions †, 2025, 13, 2227-7390, 223, 10.3390/math13020223 | |
9. | Feng Qi, Ravi Prakash Agarwal, Dongkyu Lim, Decreasing property of ratio of two logarithmic expressions involving tangent function, 2025, 31, 1387-3954, 1, 10.1080/13873954.2024.2449322 | |
10. | Xin-Le Liu, Feng Qi, Monotonicity results of ratio between two normalized remainders of Maclaurin series expansion for square of tangent function, 2025, 75, 0139-9918, 699, 10.1515/ms-2025-0051 | |
11. | Fei Wang, Feng Qi, Power series expansion and decreasing property related to normalized remainders of power series expansion of sine, 2024, 38, 0354-5180, 10447, 10.2298/FIL2429447W |