Vol 33, No 4 (2025)

Editorial

Basic elements of the BibTeX file structure

Kulyabov D.S., Korolkova A.V., Sevastianov L.A., Rybakov Y.P.

Abstract

BibTeX is used to prepare bibliographic information for our journals. This article describes the basic structure of BibTeX files.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):355-360
pages 355-360 views

Computer Science

Leaf disease recognition using deep learning methods

Muthana A.S., Lyapuntsova E.V.

Abstract

The digitalization of crop production has placed leaf-image-based disease recognition among the top research priorities. This paper presents a compact and reproducible system designed for rapid deployment in cloud environments and subsequent adaptation. The proposed approach combines multitask learning (simultaneous prediction of plant species and disease), physiologically motivated channel processing, and error-tolerant data preparation procedures. Experiments were conducted on the New Plant Diseases Dataset (Augmented). To accelerate training, six of the most represented classes were selected, with up to 120 images per class. Images were resized to 192×192 and augmented with geometric and color transformations as well as soft synthetic lesion patches. The ExG greenness index was embedded into the green channel of the input image. The architecture was based on EfficientNet-B0; the proposed HiP²-Net model included two classification heads for disease and species. Training was carried out in two short stages, with partial unfreezing of the base network’s tail in the second stage. Evaluation employed standard metrics, confusion matrices, test-time augmentation, and integrated gradients maps for explainability. On the constructed subset, the multitask HiP²-Net consistently outperformed the frozen baseline model in accuracy and aggregate metrics. Synthetic lesions reduced background sensitivity and improved detection of mild infections, while incorporating ExG enhanced leaf tissue separation under variable lighting. Integrated gradient maps highlighted leaf veins and necrotic spots, strengthening trust in predictions and facilitating expert interpretation. The proposed scheme combines the practicality of cloud deployment with simple, physiology-inspired techniques. Adopting the \enquote {species + disease} setup together with ExG preprocessing and soft synthetic lesions improves robustness to lighting, background, and geometric variations, and makes it easier to transfer models to new image collections.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):361-373
pages 361-373 views

Adaptive neural network method for multidimensional integration in arbitrary subdomains

Shcherbak M.R., Abdullina L.R., Salpagarov S.I., Fedorishchev V.M.

Abstract

Multidimensional integration is a fundamental problem in computational mathematics with numerous applications in physics, engineering, and data science. Traditional numerical methods such as Gauss–Legendre quadrature [1] and Monte Carlo techniques face significant challenges in high-dimensional spaces due to the curse of dimensionality, often requiring substantial computational resources and suffering from accuracy degradation. This study proposes an adaptive neural network-based method for efficient multidimensional integration over arbitrary subdomains. The approach optimizes training sample composition through a balancing parameter $\rho $, which controls the proportion of points generated via a Metropolis–Hastings inspired method versus uniform sampling. This enables the neural network to effectively capture complex integrand behaviors, particularly in regions with sharp variations. A key innovation of the method is its ``train once, integrate anywhere'' capability: a single neural network trained on a large domain can subsequently compute integrals over any arbitrary subdomain without retraining, significantly reducing computational overhead. Experiments were conducted on three function types---quadratic, Corner Peak, and sine of sum of squares---across dimensions 2D to 6D. Integration accuracy was evaluated using the Correct Digits (CD) metric. Results show that the neural network method achieves comparable or superior accuracy to traditional methods (Gauss–Legendre, Monte Carlo, Halton) for complex functions, while substantially reducing computation time. Optimal $\rho $ ranges were identified: 0.0--0.2 for smooth functions, and 0.3--0.5 for functions with sharp features. In multidimensional scenarios (4D, 6D), the method demonstrates stability at $\rho = 0.2\text {--}0.6$, outperforming stochastic methods though slightly less accurate than Latin hypercube sampling [2]. The proposed method offers a scalable, efficient alternative to classical integration techniques, particularly beneficial in high-dimensional settings and applications requiring repeated integration over varying subdomains.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):374-388
pages 374-388 views

Modeling and Simulation

Optimal eight-order three-step iterative methods for solving systems of nonlinear equations

Zhanlav T., Otgondorj K.

Abstract

In this paper, we for the first time propose the extension of optimal eighth-order methods to multidimensional case. It is shown that these extensions maintained the optimality properties of the original methods. The computational efficiency of the proposed methods is compared with that of known methods. Numerical experiments are included to confirm the theoretical results and to demonstrate the efficiency of the methods.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):389-403
pages 389-403 views

On calculating the dimension of invariant sets of dynamic systems

Kadrov V.M., Malykh M.D.

Abstract

This work investigates numerical approaches for estimating the dimension of invariant sets onto which the trajectories of dynamic systems ``wind'', with a focus on fractal and correlation dimensions. While the classical fractal dimension becomes computationally challenging in spaces of dimension greater than two, the correlation dimension offers a more efficient and scalable alternative. We develop and implement a computational method for evaluating the correlation dimension of large discrete point sets generated by numerical integration of differential equations. An analogy is noted between this approach and the Richardson--Kalitkin method for estimating the error of a numerical method. The method is tested on two representative systems: a conservative system whose orbit lies on a two-dimensional torus, and the Lorenz system, a canonical example of a chaotic flow with a non-integer attractor dimension. In both cases, the estimated correlation dimensions agree with theoretical predictions and previously reported results. The developed software provides an effective tool for analysing invariant manifolds of dynamical systems and is suitable for further studies, including those involving reversible difference schemes and high-dimensional systems.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):404-410
pages 404-410 views

Dual quaternion representation of points, lines and planes

Gevorkyan M.N., Vishnevskiy N.A., Didus K.V., Korolkova A.V., Kulyabov D.S.

Abstract

{Background} The bulk of the work on dual quaternions is devoted to their application to describe helical motion. Little attention is paid to the representation of points, lines, and planes (primitives) using them. {Purpose} It is necessary to consistently present the dual quaternion theory of the representation of primitives and refine the mathematical formalism. {Method} It uses the algebra of dual numbers, quaternions and dual quaternions, as well as elements of the theory of screws and sliding vectors. {Results} Formulas have been obtained and systematized that use exclusively dual quaternionic operations and notation to solve standard problems of three-dimensional geometry. {Conclusions} Dual quaternions can serve as a full-fledged formalism for the algebraic representation of a three-dimensional projective space.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):411-439
pages 411-439 views

Physics and Astronomy

Simulating QAOA operation using {Cirq} and {qsim} quantum frameworks

Palii Y.G., Bogolubskaya A.A., Yanovich D.A.

Abstract

The problem of finding the lowest-energy state in the Ising model with a longitudinal magnetic field is studied for two- and three-dimensional lattices of various sizes using the Quantum Approximate Optimization Algorithm (QAOA). The basis states of the quantum computer register correspond to spin configurations on a spatial lattice, and the Hamiltonian of the model is implemented using a sequence of quantum gates. The average energy value is efficiently measured using the Hadamard test. We simulate the QAOA operation on increasingly complex lattice configurations using the software libraries \texttt {Cirq} and \texttt {qsim}. The results of optimization, obtained using gradient-based and gradient-free methods, demonstrate the superiority of the latter in both modeling performance and quantum computer usage. Key arguments in favor of the advantages of quantum computation for this problem are presented.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):440-460
pages 440-460 views

Ar-O$_2$ plasma of resonant UHF discharge for chitosan's films processed

Artemyev A.V., Kritchenkov A.S.

Abstract

This article explores the modification of chitosan films by treating Ar-O$_2$ with microwave plasma. The main idea is to use resonant plasma generation methods to treat chitosan films. Spectral and energy characteristics of microwave plasma are obtained. The mechanical properties, swelling, and solubility of chitosan films exposed to microwave plasma are studied. The dependence of film properties on the duration of treatment with resonant microwave plasma is demonstrated.

Discrete and Continuous Models and Applied Computational Science. 2025;33(4):461-470
pages 461-470 views