bluuebunny/crossref_metadata_2025_split huggingface dataset:
Depolarizing isotropic collisions of the CN solar molecule with electrons
Authors: Derouich Moncef , Mustajab Fainana , Qutub Saleh , Ahmad Badruddin Zaheer 
Published: January 2021

Abstract
Existence of linear polarization, formed by anisotropic scattering in the photosphere, has been demonstrated observationally as well as theoretically and is called second solar spectrum (SSS). The SSS is distinguished by its structure, which is rich in terms of information. In order to analyze the SSS, it is necessary to evaluate the (de)polarizing effect of isotropic collisions between CN solar molecules and electrons or neutral hydrogen atoms. This work is dedicated to calculations of the polarization transfer rates associated with CN–electron isotropic collisions. We show that usual rates serve as a proxy for polarization transfer rates. Then, we take advantage of available usual excitation collisional rates obtained via sophisticated quantum methods in order to derive the polarization transfer rates for the X
2Σ+– B
2Σ+ (violet) and X
2Σ+–A
2Π (red) systems of CN. Our approach is based on the infinite order sudden (IOS) approximation and can be applied for other solar molecules. We discuss the effectiveness of collisions with electrons on the SSS of the CN lines. Our results contribute to reducing the degree of complication in modeling the formation of the SSS of CN.
A frequency filter of backscattered light of stimulated Raman scattering due to the Raman rescattering in the gas-filled hohlraums
Authors: Hao Liang , Huo Wen Yi , Liu Zhanjun , Li Jun , Zheng Chunyang , Ren Chuang 
Published: January 2021

Abstract
The coupling evolutions of stimulated Raman scattering (SRS) and Raman rescattering (re-SRS) are investigated under the parameter conditions of relevance to the gas-filled hohlraum experiments at the National Ignition Facility by using the nonenveloped fluid code FLAME. It is found that re-SRS works as a frequency filter of the backscattered light of SRS in the gas region. The low frequency modes of scattered light originated from a higher density region would stimulate re-SRS and be heavily depleted by re-SRS near the region of their quarter critical density. The energy in daughter waves of re-SRS is deposited in the gas plasmas. The large amplitude of the daughter Langmuir wave of re-SRS would stimulate cascade Langmuir decay instabilities and induce obvious low frequency density modulations, which can further result in the inflation of high frequency modes of scattered light of SRS at densities lower than the growth region of re-SRS.
Combinatorics for calculating expectation values of functions in systems with evolution governed by stochastic differential equations
Authors: Ohkubo Jun 
Published: January 2021

Abstract
Stochastic differential equations are widely used in various fields; in particular, the usefulness of duality relations has been demonstrated in some models such as population models and Brownian momentum processes. In this study, a discussion based on combinatorics is made and applied to calculate the expectation values of functions in systems in which evolution is governed by stochastic differential equations. Starting with the duality theory of stochastic processes, some modifications to the interpretation and usage of time-ordering operators naturally lead to discussions on combinatorics. For demonstration, the first and second moments of the Ornstein–Uhlenbeck process are re-derived from the discussion on combinatorics. Furthermore, two numerical methods for practical applications are proposed. One method is based on a conventional exponential expansion and the Padé approximation. The other uses a resolvent of a time-evolution operator, along with the application of the Aitken series acceleration method. Both methods yield reasonable approximations. Particularly, the resolvent and Aitken acceleration show satisfactory results. These findings will provide a new way of calculating expectations numerically and directly without using time-discretization.
The cubic interpolation spline for functions with boundary layer on a Bakhvalov mesh
Authors: Blatov I A , Dobrobog N V , Kitaeva E V 
Published: January 2021

Abstract
The problem of cubic spline interpolation on the Bakhvalov mesh of functions with region of large gradients is considered. Asymptotically accurate error estimates O(N
−4) are obtained for a class of functions with an exponential boundary layer in case 1/N ≤ ε, where N is number of nodes, ε is small parameter. In case ε ≤ 1/N we have experimentally shown that the error estimates of traditional spline interpolation are not uniform in a small parameter, and the error itself can increase indefinitely when the small parameter tends to zero at a fixed number of nodes N. A modified cubic spline is proposed for which uniform estimates of the order O(N
−4) have been experimentally confirmed.
Evolutionary synthesis of nonlinear models based on metaheuristic programming and templates
Authors: Monakhov Oleg 
Published: January 2021

Abstract
The application of a metaheuristic programming (MP) algorithm based on various bio-inspired algorithms for the evolutionary (metaheuristic) synthesis of nonlinear models is considered. The described approach of evolutionary synthesis uses a sequential operator structure of the chromosome, templates (with some undefined functions and parameters) of the models and the given sets of pairs of input and output data. The influence of the degree of specialization of the template on the characteristics of the search algorithm in the metaheuristic synthesis of nonlinear models defined by ordinary differential equations with undetermined functions and parameters is studied. Estimates of the complexity of this algorithm are obtained, and a significant reduction in the search time when using templates in the process of the evolutionary synthesis is shown.
Mathematical modeling of Russian northern coastal waters in the shallow water approximation
Authors: Elizarova T G , Ivanov A V , Kuleshov A A 
Published: January 2021

Abstract
In this paper, the authors present a model for computing a coastal waters flow in the shallow seas. The software implementation of the model consists in coupling the global software and the local hydrodynamic computations. The authors describe the use of the joint two computational packages: the global model for the ocean dynamics NEMO (Nucleus for European Modelling of the Ocean) which provides the initial and boundary conditions and the code WRF (Weather Research and Forecasting) for predicting meteorological conditions is used to calculate the wind loads. A hydrodynamic model based on the shallow water (SW) approximation is used to compute the coastal waters flow within a local domain, typically, 1000 km in size. The software implementation of the algorithm is based on regularized SW equations. As an example, the authors have computed the flow of the coastal waters in the vicinity of the Kara Strait. The study carried out demonstrate that all three algorithms successfully combined in the framework of the local computation and give the consistent results.
Computer simulation of coronas, glories and fogbows in atmospheric clouds and fogs
Authors: Zakovryashin A V , Prigarin S M 
Published: January 2021

Abstract
This paper deals with the development of software that allows one to compute the scattering phase functions of the optical radiation in polydisperse media consisting of spherical particles, based on the Mie scattering theory. The software also enables computer visualization of such optical phenomena as rainbows, glories and coronas. A special technique is used to significantly accelerate the integration over the radius of scattering particles and to increase the calculation rate of the scattering phase functions. Using the software developed, we have performed a detailed analysis of the scattering phase functions for a large number of well-known cloud and fog models, and have created computer images of optical phenomena (rainbows, glories, and coronas) that are inherent to the considered models.
Regularization of algorithms for estimation of errors of differential equations approximate solutions
Authors: Rogalev A N , Feodorova N A 
Published: January 2021

Abstract
When estimating the error of numerical solutions of ordinary differential equations, it is proposed to use the regularization of error estimation algorithms for approximate solutions. Regularization is considered as the use of additional a priori information about the numerical solution. A priori information is estimated by the method of the inverse error analysis, which implements the transformation of the statement of the problem of evaluating the accuracy of the numerical solution. In this case, the problem is selected so that the approximate solution is the exact solution of the transformed problem, close to the original problem. It is also possible to add some additional restrictions to the conditions of the problem. This allows us to solve the incorrectly posed problems of estimating errors in numerical solutions, which in most cases are unstable. It is known that earlier in the numerical solution of linear algebra problems the inverse error analysis was used by Wilkinson J. and also Voevodin V.V., application of the inverse error analysis in other areas of numerical analysis can be noted. Using direct and inverse error analysis Voevodin V.V. effectively calculated majorants of rounding errors in the most important methods of linear algebra and significantly developed the method of inverse error analysis.. However, the regularization process associated with the reverse analysis of errors has not been previously studied. The article discusses the characteristics of regularization in the inverse analysis of errors in the numerical solution of ordinary differential equations with initial data. The regularization of error estimation algorithms has advantages in the numerical solution of ordinary differential equations of real models of physics and technology.
The control problem for the heat equation in the case of a composite material
Authors: Tanana V P , Markov B A 
Published: January 2021

Abstract
In modern technology there are devices whose details are subject to thermal effects. As a result, the properties of materials may change in parts. In turn, this leads to the failure of the device. You can control surface temperature to protect components from excessive heat. The temperature measuring device cannot be placed at the point where the heating takes place, since the heating temperature is too high. On the other hand, the temperature of the outer side of the protective layer itself is of little interest: you need to know the temperature on the surface of the material. Therefore, one can either, knowing the temperature at the material-protective layer media section, solve the inverse problem, or solve the heating control problem. In this paper, we propose to consider the problem of controlling heating under the condition of controlling the temperature of the interface. We consider the problem on a half-line, and the following sections are identified in the problem: the heating region, a small thickness of the protective layer, the region occupied by the material, and the semi-infinite region in which the material interacts with the environment. At the same time, we consider such a coefficient of thermal conductivity that it is constant in each of the regions, but it experiences a first-order discontinuity at the interfaces. This makes it impossible to build a classical solution to the problem in the entire solution area, and we build solutions that are classic, each in its own subregion, and that meets the matching conditions at the interfaces. The control problem is as follows: the heating function, on the one hand, should be maximum all the time, and on the other, the temperature at the interface should not exceed a certain critical value (for example, the melting temperature of the material). The constructed solution of the problem is simple, but requires rather cumbersome proofs.
The Barnes — Hut-type algorithm in 2D Lagrangian vortex particle methods
Authors: Ryatina E , Lagno A 
Published: January 2021

Abstract
The Lagrangian vortex particle method for two-dimensional flow simulation around airfoils is considered. Generally, the most time-consuming operation in the vortex method is vortex particles interaction simulation, especially if it is performed directly “point-to-point” for all pairs of particles. The result of such operation is vortex particles convective velocities. This problem is similar to the N-body problem and has squared computational complexity O(N2). The only efficient approach for its solution in a reasonable time for large N is to use approximate fast algorithms. The fast method suggested by Barnes and Hut having logarithmic computational complexity is considered for the mentioned problem of convective velocities computation. It also has been adapted for other operations in the vortex method such as a system of algebraic equations iterative solution and efficient right-hand side computation. As the result, the Barnes — Hut method allows reducing the whole time of calculations by several tens of times.
Parallel speedup analysis of an adjoint ensemble-based source identification algorithm
Authors: Penenko Alexey , Gochakov Alexander 
Published: January 2021

Abstract
In the approach to the inverse problems, based on the sensitivity operators, the inverse problem is transformed into the family of quasi-linear operator equations. The sensitivity operator is constructed of the ensemble of the adjoint problem solutions corresponding to different adjoint problems source functions. Hence, from the theoretical point of view, sensitivity operator-based algorithms can be efficiently parallelized. The paper’s objective is to carry out the experimental study of the algorithm computation time for the different number of computation cores.
Parallel implementation of a numerical method for solving transport equations for the mesoscale meteorological model TSUNM3
Authors: Starchenko A V , Danilkin E A , Prohanov S A , Leshchinskiy D V 
Published: January 2021

Abstract
A parallel algorithm for numerical solution of a generalized unsteady 3-dimensional advection-diffusion equation for a mesoscale meteorological model TSUNM3 is considered. Efficiency of parallel implementation of the solver with Message Passing Interface (MPI), Open Multi-Processing (OpenMP), Open Accelerators (OpenACC), and NVidia Compute Unified Device Architecture (CUDA) technologies was compared. The efficiency of the MPI-parallelized code of TSUNM3 model with a two-dimensional domain decomposition strategy applied is not less than 75% on 256–512 processes on Cyberia supercomputer of Tomsk State University.
Influence of two modes of instructional methods on students’ academic achievement in senior secondary school mathematics in Afijio Local Government Area of Oyo
Authors: Jonah B. A. , Ogundile O. P. 
Published: January 2021

Abstract
The increase in the failure rate of students sitting for final year exams, for example, West Africa Senior School Certificate Examination (WASSCE) in mathematics, is a serious concern to both students, teachers, and parents. A review of the WASSCE results statistics by the National Bureau of Statistics (2016-2018) indicated that the achievement of learners in mathematics knowledge, especially in Oyo State in private senior secondary schools, continued to reduce. For example, the percentage of students who have 5% credits and above, including Mathematics is 24% in 2016, the performance reduced to 16.8% in 2017 while in 2018 the result remained at 17.2% [1]. Also, a review of the Chief Examiner’s comment on students’ weaknesses in general mathematics paper two from (2009-2018) shows that students’ weaknesses are primarily expressed in the areas of circle geometry and its application, word problems, and interpretation of graphs [2]. In dealing with these weaknesses, the Chief Examiner suggested that teachers should use instructional aids in teaching and learning processes, teachers should give more worked examples during class lessons and a more appropriate teaching method be employed. Therefore, this research work was carried out to examine if a change in teaching method will influence students’ academic performance in Mathematics. In this research, the two methods adopted by the researcher are the Traditional (chalk and talk) method and the Montessori (self-discovery) method. The tools used for data collection were Mathematics Achievement Test (M. A. T), interview, and field observation. Analysis of the results gathered revealed that students that were taught using the Montessori method had a cumulative 57.1% pass. In comparison, their counterparts who used the traditional way had an overall 49.6% pass. These findings revealed that participants from the experimental group performed better than students in the control group.
Trends and usage pattern of SPSS and Minitab Software in Scientific research
Authors: Okagbue Hilary I. , Oguntunde Pelumi E. , Obasi Emmanuela C. M. , Akhmetshin Elvir M. 
Published: January 2021

Abstract
Most scientific research generates data. Analysis of the data from scientific research helps create new knowledge or a deep understanding of natural phenomena. Statistical software is used mainly in data analysis. SPSS and Minitab appear to be most popular, especially for those that could neither code nor mathematical inclined to handle advanced software such as R, MATLAB, Maple, etc. Trends and usage pattern of SPSS and Minitab Software in Scientific research was studied in this paper with the data obtained from the Scopus database. In their abstracts or keywords, documents that have mentioned SPSS were extracted for the years 2010 to 2019. Frequency analysis showed that the trend of using SPSS and Minitab is steadily increasing, although the use of Minitab is a fraction of SPSS. Minitab is mostly used in engineering, materials science, and computer science, while SPSS is mainly used in medicine, social science, and engineering. Analysis of the document type showed that SPSS and Minitab are mostly stated in abstracts or keywords of research articles, conference papers, review papers, and books indexed in Scopus.
Application of the regular perturbation method for the solution of first-order initial value problems
Authors: Obeya Peace O. , Akinlabi Grace O. 
Published: January 2021

Abstract
Several analytical and numerical methods are globally used in the solution of linear and non-linear ordinary differential equations. In recent times, an analytical method called the perturbation method was proposed by JiHuan He. This technique involves the use of the perturbation parameter, ε. The types of perturbation method which are usually used in Mathematics are the regular perturbation method and the singular perturbation method. In this research, various numerical examples of first-order IVPs are solved using the regular perturbation method. This method gives an approximate analytical solution to the first order IVPs and are discovered to be efficient and easy to adopt.
Fractional coupled decomposition approach for the solution of a linear Klein–Gordon equation
Authors: Edeki S. O. , Ogundile O. P. , Achudume C. , Odo C. E. 
Published: January 2021

Abstract
In this article, the solution of the time-fractional linear Klein-Gordon Equation (TFLKGE) is considered. This is in combination with Laplace Decomposition Method (LDM) and Fractional Complex Transform (FCT), herein referred to as FCLDM. In contrast with the standard LDM, this proposed approach demonstrates a feasible improvement and efficiency in use. Considerations are made Illustratively using some examples, and a closed solution of the problem is obtained with ease. The FCLDM is recommended for physical modeling of real-life problems both in pure and applied sciences and for strongly non-linear differential models.
The impacts of outdoor concentration of nitrogen dioxide on its indoor level
Authors: Elehinafe F. B. , Okedere O. B. , Fakinle B. S. , Sonibare J. A. 
Published: January 2021

Abstract
This study examined the infiltration of oxides of nitrogen (NOx) from outdoor into the indoor environments in the commercial areas of Osogbo, Nigeria. Outdoor NOx concentrations were monitored at four different locations with a high volume of commercial and vehicular activities using Toxirae II NOx monitor. A control sampling point was also set at another location with no commercial and vehicular activities. The indoor concentrations at each location were simulated using IAQX 1.0f simulation tool of the US EPA. The mean measured outdoor NOx concentration over the entire commercial area ranged between 0.14 and 0.58 ppm with an average of 0.351 ppm but at the control point it ranged between 0.0 and 0.2 ppm with an average of 0.027 ppm. A simulation of the indoor concentration revealed an unhealthy indoor air quality. The stabilized indoor concentrations at commercial areas ranged between 0.054 and 0.169 ppm but it was 0.00917 ppm at the control point. The study establishes that emissions associated commercial activities may contribute significantly to indoor air quality degradation in an unplanned area thus calls for appropriate regulatory measures to protect public health.
Challenges and clarification on creating input files for metallic materials in the noncollinear spin-orbit case and band structure within GGA in Quantum Espresso: Ni as a case study
Authors: Pasanaje Adewale H , Bolarinwa Sherifdeen O , AlShaikhi Abdullah A 
Published: January 2021

Abstract
We have explicitly illustrated the challenges faced in creating input files for metallic materials in Quantum espresso by calculating the band structure of Ni and clarifying with the flags provided in this work. In this paper, we calculated the band structure of Ni after optimizations of the lattice constant, kinetic energy cutoff, ecutrho, k-points and described the basic parameters required for metallic materials. The input files provided in our work have been set such that the problem of spin/noncolin parameters and challenges faced by researchers trying to find the band structure of metallic materials have been solved. Some of these are presence of smearing, tprnfor, default nbnd, lspinorb, e.t.c.