Abstract
Quantum calculus (also known as the q-calculus) is a technique that is similar to traditional calculus, but focuses on the concept of deriving q-analogous results without the use of the limits. In this paper, we suggest and analyze some new q-iterative methods by using the q-analogue of the Taylor’s series and the coupled system technique. In the domain of q-calculus, we determine the convergence of our proposed q-algorithms. Numerical examples demonstrate that the new q-iterative methods can generate solutions to the nonlinear equations with acceptable accuracy. These newly established methods also exhibit predictability. Furthermore, an analogy is settled between the well known classical methods and our proposed q-Iterative methods.
1. Introduction
In most scientific and engineering applications, the problem of finding the solution of nonlinear equations have become an active area of research. Many researchers have explored various order iterative methods to find solutions of the nonlinear equations using various techniques such as homotopy perturbation technique, variational iterative methods and decomposition technique, for details, see [1,2,3,4,5,6,7,8,9,10,11]. Firstly, Traub [12] initiated the study of the iterative methods for the solution of the nonlinear equations and introduced a basic quadratic convergent Newton iterative method for the solution of the nonlinear equations, which have much significance in the literature. Later on, in order to improve efficiency and local order of convergence of the Newtons method, Cordero and Torregrosa [13], Frontini and Sormani [14], Hasanov [15], Weerakoon and Fernando [16] and Ozban [17] have presented different modifications of the Newton’s method using quadrature rules. Daftardar-Gejji and Jafari [18] have used different modifications of Adomian decomposition method [19] and suggested a simple technique that does not need derivative evaluation of the Adomian polynomial, which is major advantage of using this technique over Adomian decomposition method. Saqib and Iqbal [20] and Ali et al. [21,22] have used this decomposition technique and developed a family of iterative methods with better efficiency and convergence order for solving the nonlinear equations. This study shifts the paradigm of determining higher order iterative methods for solving the nonlinear equations towards the q-analogue of the iterative methods in the q-calculus.
In the last quarter of the 20th century, q-calculus appeared as an amalgamation of mathematics and physics (see [23,24,25,26,27,28,29]), and much consideration has been given by many researchers because of its wide range of applications in many fields of mathematics such as combinatorics, theory of relativity, mechanics, number theory and orthogonal polynomials. Firstly, Jackson [30] introduced the q-Taylor’s formula. Then, Jing and Fan [31] derived q-Taylor’s formula with its q-remainder by using the q-differentiation approach and established results on the q-remainder in the q-Taylor’s formula. Ernest [32] presented the four different q-Taylor’s formulas along with q integral remainder. Prashant et al. [33] have used the q-Taylor’s formula and investigated the q-analogue of the iterative methods, particularly the q-analogue of generalized Newton Raphson method and the q-analogue of the Newton Raphson method for the solution of algebraic transcendental equations and compared the accuracy of the results obtained by the classical methods. Many linear and nonlinear models appearing in science and engineering problems can be modeled by using the q differential equations. Jafari et al. [34] have adopted Daftardar decomposition technique for solving the q difference equations and also determined the convergence of the method.
In this study, we determine the q-analogue of the iterative methods proposed and suggested by Noor and Noor [35] and Ullah et al. [36] with the help of the q-Taylor’s series and decomposition technique [14].
Now, we recall some of the basic results in the area of the q-calculus [37] for that will support the development of our proposed q-iterative methods for the solution of the nonlinear equations.
Let q∈(0,1) the q-integer be defined as:
For q factorial and for , the q binomials are defined as:
Definition 1
(see [37]). The q-derivative for real valued continuous function is defined as follows
When , then the q-derivative is reduced to the standard derivative. Furthermore, the q-derivative can be represented as , and it is known as the Jackson Derivative. The higher order q-derivative for the function is given as
Definition 2
(see [37]). The q-derivative of product and quotient of function and is defined as follows
Definition 3
(see [30,31,32]). Let be a continuous function on some interval and [a,b] then Jackson q-Taylor’s formula is given as:
where,
where and are all q-derivatives.
The rest of this article is organized as follows: in Section 2, the structures of the q-iterative methods will be designed by proposing the Lists A–C. In Section 3, we deal with the convergence analysis of the proposed q-iterative methods, and it is established that these methods have the same order of convergence as the classical methods for . In Section 4, we present some of the examples to check the efficacy and performance of these methods. Furthermore, the comparisons of the results obtained by q-iterative methods with the previously known iterative methods will be discussed in the same section. Section 5 explores a general form of the q-iterative method based on the proposed iterative methods. Finally, the findings of our article are given in Section 6.
2. Construction of the -Iterative Methods
In this section, some new different order multi-step q-iterative methods are constructed by considering the Taylor’s series in the q-calculus. Here, we consider the nonlinear equation
Suppose that is the root of Equation (8) and is an initial guess in the neighborhood of . By the same technique used in [28], we rewrite the nonlinear Equation (8) as the coupled system of equations by using the Taylor’s series in the neighborhood of in the q-calculus:
Since , the relation (10) can be written as:
where
and
is a nonlinear operator and c is treated as constant.
It is noted that if we consider as an initial guess, then from (10), we have
It is wort mentioning that Equation (15) plays a very significant role in the development of new multi-step q-iterative methods. Now, we establish a sequence of higher order iterative methods implementing the decomposition technique presented by Daftardar-Gejji and Jafari [18]. The main idea behind the implementation of this technique is to find out the solution of q-type functional Equation (12) in terms of infinite series:
Now, we decompose the operator defined in (14), such as:
It follows that
and
Theorem 1
Proof.
So, the series x= converges uniformly and absolutely to the solution of Equation (12) (see [38]). It is noted that x is approximated by
and thus .
This completes the proof. □
Our iterative techniques proceed with the following algorithms:
- List A:
- From (19), we have forThis formulation suggests the following iterative scheme for solving the nonlinear Equation (8). Now, for the given initial guess , the approximate solution is computed by the iterative representationThis represents the Newton’s method in the q-calculus which has quadratic convergence. It is proved by Singh et al. [33].This method resembles the method of secants (chords).
- List B:
- From (19), we have forThis formulation suggests the following iterative scheme for solving the nonlinear Equation (8).For the given initial guess , the approximate solution is computed by the following iterative method:This is q-analogue of Chun method [3], which has cubic convergence for . The error term for this algorithm is computed in Theorem (2).
- List C:
- Again, from (19), we have forThis formulation allows us to suggest the following iterative method for solving the nonlinear Equation (8).For the given initial guess , the approximate solution is computed by the following iterative method:This is q-analogue of convergent iterative method was investigated by Ullah et al. [36]. Furthermore, it has fourth order convergence for q = 1. The Error equation for this algorithm is computed in Theorem (2).
3. Convergence Analysis
This section is comprised of the convergence analysis of the q-iterative methods determined by Lists B and C in the previous section.
Theorem 2.
Let be an open interval and be a differentiable function. If is a simple root of and is sufficiently close to α, then the convergence order of multi-step methods determined byLists BandChave convergence of the order at least three and four, respectively, and we write it as and , where q represents q-calculus. Furthermore, it satisfies the error equations
Proof.
Expanding and in terms of q-Taylor’s series about to get
where
Expanding in terms of Taylor’s series about to get
Expanding in terms of Taylor’s series about to get
This completes the proof. □
4. Numerical Examples and Comparison Results
This section elaborates on the efficacy of algorithms introduced in this paper with the support of examples. All the numerical experiments are performed with Intel (R) Core [TM] 2 × 2.1 GHz, 12 GB of RAM, and all the codes are written in Maple. We use and obtain an approximated simple root rather than the exact based on the exactness of the computer.
For the computational work, we use the following stopping criteria:
Abbreviation is used for classical iterative method and for the q-analogue of classical iterative method, and term div is used for divergence of method.
Recall the classical List 2.2 in [35] (), defined by
and the classical List 2.3 in [36] (), defined by
For simplicity, we denote the iterative Lists B and C by and , respectively. The computational results are presented in Table 1, Table 2, Table 3, Table 4, Table 5 and Table 6 to elaborate the performance and efficacy of our q iterative methods that is the main motivation of transformation of the classical methods towards the q-iterative methods.
Table 1.
Calculation of and for and different values of q by using .
Table 2.
Calculation of and for and different values of q by using .
Table 3.
The computed values of and for and different values of q by using .
Table 4.
The computed values of and for and different values of q by using .
Table 5.
The calculated values of and for and different values of q by using .
Table 6.
The calculated values of and for and different values of q by using .
For simplicity, initially in Examples 1–3, we check the performance of q-iterative methods with the classical methods for different values of q up to three iterations. Similarly, we can check the performance of the q-iterative methods for the different values of q for the rest of the iterations until we achieve the desired accuracy.
Example 1
(see [3]). We consider the nonlinear equation:
The exact solution for this example is . We take as an initial guess. Table 1 shows the computation of and for and different values of q by using .
Proceeding in the way of Table 1, we get for different values of q, which is the required solution. One can observe from Table 1 that more accurate values of s can be obtained when q approaches towards one and for which tend towards zero. The values of = 2.746138e + 01, = 5.942719e + 00, = 5.488326e − 01 calculated by at q = 0.9999 are closer to zero as compared to the values = 2.747477e + 01, = 5.949309e + 00, = 5.505169e − 01 calculated by . Furthermore, Equation (51) converges towards the root = 1.2076478271 for q = 0.9999 and = 4.435401e − 12. Table 2 shows the computation of and for i = 1, 2, 3 for different values of q by using the List C .
Proceeding in the way of Table 2, we get the required solution x = 1.2076478271. From Table 2, we see that if q approaches one, we can obtain more accurate values of s for which s tends towards zero, where . It is also observe that the values of = 2.117115e + 01, = 2.896627e + 00, = 3.622758e − 02 at q = 0.9999 calculated by are closer to zero as compared to the values of = 2.118172e + 01, = 2.900487e + 00, = 3.644647e − 02 calculated by . Furthermore, Equation (51) converges to the root = 1.2076478271 for q = 0.9999 and = 1.424874e − 20.
Example 2
(see [39] (Population growth model)). Consider the nonlinear equation
This equation appears in the mathematical modeling of the growth of population over short periods of time, where λ denotes the constant birth rate of population whose value needs to determined.
For computational work, we take = 1.5 as an initial estimate. The solution of this example approximated to 16 decimal digits is 0.1009979296857498. In Table 3, we compute the values of and for different values of q by using .
Proceeding as the way of Table 3, we get the required solution . From Table 3, It can easily observe that we obtain more accurate values of when q approaches one and for which tend towards zero. The values of = 6.591112e + 05, = 2.736999e + 04, = 4.839200e + 00 at q = 0.9999 computed by are closer to zero as compared to the other values of = 6.592007e + 05, = 2.738286e + 04, = 4.850247e + 00 computed by . Furthermore, Equation (52) converges towards the root = 0.1009979297 in the fifth iteration for q = 0.9999 and = 4.545278e − 22.
Meantime, in Table 4, we compute the values of and for different values of q by using .
We can observe from Table 4 that we get more accurate values of when q approaches one and for which tend towards zero. In addition, the values of = 4.206350e + 05, = 2.169407e + 03, = 3.799508e − 06 calculated by at are closer to zero as compared to the values = 4.207000e + 05, = 2.171013e + 03, = 3.859455e − 06 calculated by . Furthermore, Equation (52) converges towards the root in the fourth iteration for q = 0.9999 and = 4.103556e − 22.
Example 3
(see [40]). Consider the van der Waal’s equation
This equation is used to interpret the real and ideal gas behavior that has been converted to the non-linear form after choosing the appropriate values of the parameters. Its exact solution is x = 1.92984624284786221849. Here, we take = 3.10.
By proceeding as the above table, we can obtain the required solution x = 1.9298462428. From Table 5, we can observe that we get more accurate values of for which tend towards zero when q approaches one. The values of = 4.378340e − 01, = 7.835843e − 02, = 1.283785e − 02 at q = 0.9999 computed by are closer to zero as compared to the values of = 4.379863e − 01, = 7.842636e − 0, = 1.286153e − 02 computed by . Furthermore, Equation (53) converges towards the root = 1.92984624284786221850 in the seventh iteration for q = 0.9999 and = 3.081547e − 18.
The computational results obtained from Table 6 illustrate the accuracy of the values of when q approaches one and for which tend towards zero. Moreover, the values of = 3.105124e − 01, = 3.856881e − 02, = 3.623214e − 03 at q = 0.9999 computed by , are closer to zero as compared to = 3.106207e − 01, = 3.860481e − 02, = 3.632441e − 03 computed by . Furthermore, Equation (53) converges towards the root = 1.92984624284786221849 in the sixth iteration for q = 0.9999 and = 2.935505e − 21.
4.1. Error Analysis and Application of the q-Iterative Methods
Error is considered as the difference between a true value and an estimate (see [39]), or an approximation, it can easily be observed from the numerical values that if we compute the errors of q-iterative methods than they fluctuate for different values of q. The error decreases when q approaches to the extreme values between 0 and 1. In view of this result, the q-iterative methods are calculated for a large value of , which will approximate the ordinary iterative methods.
| List B | |||
| Nonlinear equation | True Solution | Approximate solution at q = 0.9999 | Error |
| Equation (51) | 1.20764782713091892701 | 1.20764782713091892700 | 7.187741e-21 |
| Equation (52) | 0.10099792968574978895 | 0.10099792968574978895 | 3.394397e-28 |
| Equation (53) | 1.92984624284786221849 | 1.92984624284786218283 | 3.565288e-17 |
| List C | |||
| Nonlinear equation | True Solution | Approximate solution at q = 0.9999 | Error |
| Equation (51) | 1.20764782713091892701 | 1.20764782713091892701 | 7.016521e-22 |
| Equation (52) | 0.10099792968574978895 | 0.10099792968574978895 | 3.064831e-28 |
| Equation (53) | 1.92984624284786221849 | 1.92984624284786221845 | 3.396321e-20 |
4.2. Comparison of the Classical and q-Analogue of Iterative Methods
Here, we check the robustness and efficiency of our new iterative methods by considering some of the nonlinear equations. Furthermore, we compare the standard Newton’s method (), fourth order Chun method () (see [3]), and with our new iterative methods and . In Table 7, we display the number of iterations (), the approximate root , the value and be the distance between two successive estimations. It is important to mention that in order to get better computational results of the q-iterative methods, we take the value of .
Table 7.
The methods and their , , and .
Table 7 compares the solutions obtained by using the classical and our the q-iterative methods. The results show that our q-analogue iterative methods and give the same results as the classical methods and . The functions are not differentiable at and , respectively, when we choose and as initial guesses for and , respectively. Then, the iterative methods: and fail, while the new iterative methods and are applicable and give rapid convergent results.
Remark 1
(see [12]). The efficiency index is considered as , where P represents the order of the method and m is the total number of function evaluations per iteration necessary by the method.
- Efficiency index of is .
- Efficiency index of is .
- Efficiency index of is .
- Efficiency index of is .
We conclude that the efficiency indexes calculated by and are the same as those calculated by and .
5. Generalization of the Iterative Scheme in -Calculus
In this section, based on our previous results, we determine the generalized q-iterative scheme. By adding the values of in (19), we obtain
From (22), we have
Now, if x is approximated by
This formulation allows us to suggest the following generalized q iterative method:
The order of convergence of the iterative scheme is for and the number of functional evaluations is also as well.
6. Conclusions
The main target of this article is to introduce novel algorithms for solution of the nonlinear equations in the context of the q-calculus. The new algorithms are introduced by using the Daftardar–Jafari decomposition technique. The comparison of these newly established algorithms with the classical methods reflects that the proposed q-iterative methods are reliable and best alternatives to the already known algorithms. The computational results conclude that the q-analogue of the iterative methods for solving the algebraic nonlinear equations generate the same results as the classical methods, but convergence rate towards approaching the root is higher than convergence rate suggested by the classical methods. Furthermore, the errors associated with the proposed methods are comparatively lesser by the appropriately chosen value of q being close to one. The difficulty in this method, which needs future investigation, is that we need to estimate the value of .
Author Contributions
Conceptualization, G.S., P.O.M. and M.A.N.; methodology, G.S., P.O.M. and D.Y.S.; software, P.O.M., D.Y.S. and M.A.N.; validation, P.O.M., D.Y.S. and M.S.O.; formal analysis, P.O.M. and D.Y.S.; investigation, P.O.M.; resources, P.O.M. and M.A.N.; data curation, G.S., P.O.M. and D.Y.S.; writing—original draft preparation, G.S. and D.Y.S.; writing—review and editing, G.S., P.O.M. and M.S.O.; visualization, D.Y.S.; supervision, P.O.M., M.A.N. and D.Y.S. All authors have read and agreed to the final version of the manuscript.
Funding
This research received no external funding.
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Acknowledgments
We would like to express our sincere gratitude to the anonymous referees for their helpful comments that will help to improve the quality of the manuscript.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Mohammed, P.O.; Machado, J.A.T.; Guirao, J.L.G.; Agarwal, R.P. Adomian decomposition and fractional power series solution of a class of nonlinear fractional differential equations. Mathematics 2021, 9, 1070. [Google Scholar] [CrossRef]
- Mohammed, P.O.; Alqudah, M.A.; Hamed, Y.S.; Kashuri, A.; Abualnaja, K.M. Solving the modified regularized long wave equations via higher degree B-spline algorithm. J. Funct. Space 2021, 2021, 5580687. [Google Scholar]
- Chun, C. Iterative methods improving Newton’s method by the decomposition method. Comput. Math. Appl. 2005, 50, 1559–1568. [Google Scholar] [CrossRef]
- Noor, M.A.; Waseem, M.; Noor, K.I.; Ali, M.A. New iterative technique for solving nonlinear equations. Appl. Math. Comput. 2015, 265, 1115–1129. [Google Scholar]
- Hamasalh, F.K.; Mohammed, P.O. Generalized quartic fractional spline interpolation with applications. Int. J. Open Probl. Compt. Math. 2015, 8, 67–80. [Google Scholar] [CrossRef]
- Solaiman, O.S. Two new efficient sixth order iterative methods for solving nonlinear equations. J. King. Saud Uni. 2019, 31, 701–705. [Google Scholar] [CrossRef]
- Sana, G.; Noor, M.A.; Noor, K.I. Some multistep iterative methods for nonlinear equation using quadrature rule. Int. J. Anal. Appl. 2020, 18, 920–938. [Google Scholar]
- Alqudah, M.A.; Mohammed, P.O.; Abdeljawad, T. Solution of singular integral equations via Riemann–Liouville fractional integrals. Math. Prob. Eng. 2020, 2020, 1250970. [Google Scholar] [CrossRef]
- Wu, J.; Yuan, J.; Gao, W. Analysis of fractional factor system for data transmission in SDN. Appl. Math. Nonlinear Sci. 2019, 4, 191–196. [Google Scholar] [CrossRef]
- Kurt, A.; Şenol, M.; Tasbozan, O.; Chand, M. Two reliable methods for the solution of fractional coupled Burgers’ equation arising as a model of Polydispersive sedimentation. Appl. Math. Nonlinear Sci. 2019, 4, 523–534. [Google Scholar] [CrossRef]
- Touchent, K.A.; Hammouch, Z.; Mekkaoui, T. A modified invariant subspace method for solving partial differential equations with non-singular kernel fractional derivatives. Appl. Math. Nonlinear Sci. 2020, 5, 35–48. [Google Scholar] [CrossRef]
- Traub, J.F. Iterative Methods for Solution of Equations; Prentice-Hall: Englewood Cliffs, NJ, USA, 1964. [Google Scholar]
- Cordero, A.; Torregrosa, J.R. Variants of Newton’s method using fifth-order quadrature formulas. Appl. Math. Comput. 2007, 190, 686–698. [Google Scholar]
- Frontini, M.; Sormani, E. Some variants of Newtons method with third order convergence. Appl. Math. Comput. 2003, 140, 419–426. [Google Scholar]
- Hasanov, V.I.; Ivanov, I.G.; Nedzhibov, G. A new modification of Newton method. Appl. Math. Eng. 2002, 27, 278–286. [Google Scholar]
- Weerakoon, S.; Fernando, T.G.I. A variant of Newton’s method with accelerated third-order convergence. Appl. Math. Lett. 2000, 13, 87–93. [Google Scholar] [CrossRef]
- Ozban, A.Y. Some New variants of Newton’s method. Appl. Math. Lett. 2004, 17, 677–682. [Google Scholar] [CrossRef]
- Daftardar-Gejji, V.; Jafari, H. An iterative method for solving nonlinear functional equations. J. Math. Anal. Appl. 2006, 316, 753–763. [Google Scholar] [CrossRef]
- Adomian, G. Nonlinear Stochastic Systems and Applications to Physics; Springer Science & Business Media: Dordrecht, The Netherlands, 1989; Volume 46. [Google Scholar]
- Saqib, M.; Iqbal, M. Some multi-step iterative methods for solving nonlinear equations. Open J. Math. Sci. 2017, 1, 25–33. [Google Scholar] [CrossRef]
- Ali, F.; Aslam, W.; Ali, K.; Anwar, M.A.; Nadeem, A. New family of iterative methods for solving nonlinear models. Discret. Dyn. Nat. Soc. 2018, 2018, 9619680. [Google Scholar] [CrossRef]
- Ali, F.; Aslam, W.; Khalid, I.; Nadeem, A. Iteration methods with an auxiliary function for nonlinear equations. J. Math. 2020, 2020, 7356408. [Google Scholar] [CrossRef]
- Ernst, T. A New Notation for q-Calculus a New q-Taylor’s Formula; UUDM Report; Department of Mathematics, Uppsala University: Uppsala, Sweden, 1999; pp. 1–28. [Google Scholar]
- Koelink, E. Eight lectures on quantum groups and q-special functions. Rev. Colomb. Mat. 1996, 30, 93–180. [Google Scholar]
- Alqudah, M.A.; Kashuri, A.; Mohammed, P.O.; Abdeljawad, T.; Raees, M.; Anwar, M.; Hamed, Y.S. Hermite-Hadamard integral inequalities on coordinated convex functions in quantum calculus. Adv. Differ. Equ. 2021, 2021, 264. [Google Scholar] [CrossRef]
- Eryılmaz, A. Spectral analysis of q-sturm-liouville problem with the spectral parameter in the boundary condition. J. Funct. Spaces 2012, 2012, 736437. [Google Scholar] [CrossRef]
- Erzan, A. Finite q-differences and the discrete renormalization group. Phys. Lett. A 1997, 4–6, 235–238. [Google Scholar] [CrossRef]
- He, J.H. A new iteration method for solving algebraic equations. Appl. Math. Comput. 2003, 135, 81–84. [Google Scholar] [CrossRef]
- Koornwinder, T.H.; Swarttouw, R.F. On q-analogues of the Fourier and Hankel transforms. Trans. Am. Math. Soc. 1992, 333, 445–461. [Google Scholar]
- Jackson, F.H. A q-form of Taylors formula. Mess. Math. 1909, 38, 62–64. [Google Scholar]
- Jing, S.C.; Fan, H.Y. q-Taylor’s Formula with its q remainder. Commun. Theor. Phys. 1995, 23, 117–120. [Google Scholar] [CrossRef]
- Ernst, T. A method for q-calculus. J. Nonlinear Math. Phys. 2003, 10, 487–525. [Google Scholar] [CrossRef]
- Singh, P.; Mishra, P.K.; Pathak, R.S. q-iterative methods. IOSR J. Math. 2013, 9, 6–10. [Google Scholar] [CrossRef]
- Jafari, H.; Johnston, S.J.; Sani, S.M.; Baleanu, D. A decomposition method for solving q-difference equations. Appl. Math. Inf. Sci. 2015, 9, 2917–2920. [Google Scholar]
- Noor, M.A.; Noor, K.I. Three step iterative methods for nonlinear equations. Appl. Math. Comput. 2006, 183, 322–327. [Google Scholar]
- Ullah, M.Z.; Ahmad, F.; Jbbar, M.A.A.A. A correction note on three-step iterative methods for nonlinear equations and generalization of method. J. Mod. Methods Num. Anal. 2014, 5, 10–16. [Google Scholar] [CrossRef][Green Version]
- Kac, V.; Cheung, P. Quantum Calculus; Springer: New York, NY, USA, 2002. [Google Scholar]
- Cherruault, Y. Convergence of Adomians method. Kybernetes 1989, 18, 31–38. [Google Scholar] [CrossRef]
- Burden, R.L.; Faires, J.D. Numerical Analysis; PWS Publishing Company: Boston, MA, USA, 2001. [Google Scholar]
- Waals, V.D.; Diderik, J. Over de Continuiteit van den Gasen Vloeistoftoestand (on the Continuity of the Gas and Liquid State). Ph.D. Thesis, University of Leiden, Leiden, The Netherlands, 1873. [Google Scholar]
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. |
© 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).