bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dual approach as empirical reliability for fractional differential equations
Authors: Dubovski P B , Slepoi J A 
Published: December 2021

Abstract
Computational methods for fractional differential equations exhibit essential instability. Even a minor modification of the coefficients or other entry data may switch good results to the divergent. The goal of this paper is to suggest the reliable dual approach which fixes this inconsistency. We suggest to use two parallel methods based on the transformation of fractional derivatives through integration by parts or by means of substitution. We introduce the method of substitution and choose the proper discretization scheme that fits the grid points for the by-parts method. The solution is reliable only if both methods produce the same results. As an additional control tool, the Taylor series expansion allows to estimate the approximation errors for fractional derivatives. In order to demonstrate the proposed dual approach, we apply it to linear, quasilinear and semilinear equations and obtain very good precision of the results. The provided examples and counterexamples support the necessity to use the dual approach because either method, used separately, may produce incorrect results. The order of the exactness is close to the exactness of fractional derivatives approximations.
A discontinuous shapeless particle method for the quasi-linear transport
Authors: Bogomolov S V , Kuvshinnikov A E 
Published: December 2021

Abstract
This paper considers a new version of the discontinuous particle method, whose higher accuracy is based on the “predictor-corrector” scheme. The peculiarity of this version is a new criterion of rearranging particles at the “corrector” stage. In contrast to the previously used version with the analysis of overlapping particles, which required an assumption about their form, we use another key characteristic of particles, namely, their mass, more precisely, the assumption that in the nonlinear elastic transport not only particle masses are conserved but also the mass located between the centers of these particles. This requirement leads to the fact that changing a distance between particles in the process of their movement and conservation of mass in the space between them, lead to a change in the density of one of the particles. A new version arose in the solution of the two-dimensional transport problems. We emphasize that the discontinuity is smeared into a single particle, which indicates to a high accuracy of the method. The construction of the method for a simple nonlinear transport problem is a necessary step to simulate the complex gas dynamics problems.
Crystal structures and continued fractions
Authors: Pekhtereva L V , Seleznev V A 
Published: December 2021

Abstract
In this paper, we consider the properties of a flat crystal structure associated with the matrix representation of finite continued fractions generating unimodular morphisms of a flat integer lattice. The used matrix representations of the continued fractions and their properties are obtained in [1]. The constructed model allows us to explain the existing limitations of the sets of Weiss parameters (the rational ratio of the lengths of the edges of the forming cell) of crystals by the Gauss-Kuzmin distribution of natural numbers in the representation of continued fractions.
An iterative method for solving difference problems of gas dynamics in the mixed Euler-Lagrangian variables
Authors: Sablin M 
Published: December 2021

Abstract
The method proposed is intended to solve implicit conservative operator difference schemes for a grid initial-boundary value problems on a simplex grid for a system of equations of gas dynamics in the mixed Euler-Lagrangian variables. To find a solution to such a scheme at a time step, it is represented as a single equation for a nonlinear function of two arguments from space – the direct product of the grid spaces of gas-dynamic quantities. To solve such an equation, a combination of the generalized Gauss-Seidel iterative method (external iterations) and an implicit two-layer iteration scheme (internal iterations at each external iteration) is used. The feature of the method is that, the equation, which is solved by internal iterations, is obtained from the equation of the difference scheme using symmetrization – such a non-degenerate linear transformation that the function in this equation has a self-adjoint positive Frechet derivative.
Modelling chronic hepatitis B using the Marchuk-Petrov model
Authors: Yu Khristichenko M , Nechepurenko Yu M , Grebennikov D S , Bocharov G A 
Published: December 2021

Abstract
Systems of time-delay differential equations are widely used to study the dynamics of infectious diseases and immune responses. The Marchuk-Petrov model is one of them. Stable non-trivial steady states and stable periodic solutions to this model can be interpreted as chronic viral diseases. In this work we briefly describe our technology developed for computing steady and periodic solutions of time-delay systems and present and discuss the results of computing periodic solutions for the Marchuk-Petrov model with parameter values corresponding to the hepatitis B infection.
Comparison of genomes of different species of coronaviruses using spectra of periodicities
Authors: Miroshnichenko L A , Gusev V D , Dzhioev Yu P 
Published: December 2021

Abstract
In the genomes of different organisms, there are periodicities, i.e. fragments of DNA (RNA)-sequences formed by tandem repetition of the basic monomer (period). The spectra of periodicities with lengths exceeding the ‘noise’ threshold are quite compact and visible even for complete genomes. This makes them an acceptable tool for differentiating closely related objects. The objects of analysis in this work are the periodicities at genomes of three species of coronavirus: MERS, SARS, and SARS-CoV-2. It has been shown that there are markers in the form of periodicities that make it possible to distinguish between these species of coronaviruses. None of the periodicities identified in the genomes of the MERS species (except for the poly-a tract in the 3‘UTR) is found in the genomes of SARS and SARS-CoV-2 and vice versa. Revealed periodicities common to SARS and SARS-CoV-2, as well as inherent only to genomes of one species. The number of periodicities in SARS and SARS-CoV-2 significantly exceeds the number of periodicities in random sequences. The periodicities found in almost all genomes of only ‘their’ species are of the greatest interest in terms of revealing the pathogenic potential of the virus.
Algorithm for inversion of resistivity logging-while-drilling data in 2D pixel-based model
Authors: Bondarenko A V , Yu Kushnir D , Velker N N , Dyatlov G V 
Published: December 2021

Abstract
Multi-frequency and multi-component extra-deep azimuthal resistivity measurements with depth of investigation of a few tens of meters provide advanced possibilities for mapping of complex reservoir structures. Inversion of the induction measurements set becomes an important technical problem. We present a regularized Levenberg–Marquardt algorithm for inversion of resistivity measurements in a 2D environment model with pixel-based resistivity distribution. The cornerstone of the approach is an efficient parallel algorithm for computation of resistivity tool signals and its derivatives with respect to the pixel conductivities using volume integral equation method. Numerical tests of the suggested approach demonstrate its feasibility for near real time inversion.
An extrapolation method for projection data fltration in pulsed X-ray tomography
Authors: Yarovenko I P , Prokhorov I V 
Published: December 2021

Abstract
This paper deals with an inverse problem that consists of an attenuation coefficient identification for the non-stationary radiation transfer equation. To solve the problem, we propose a method that uses several pulses of radiation to extrapolate ideal projection data corresponding to a non-scattering medium. Numerical experiments on the Shepp-Logan phantom show that the method proposed improves the reconstruction quality.
Numerical modeling of fault structures in the Kurai basin of Gorny Altai based on data from direct current methods
Authors: Sanchaa A M , Nevedrova N N , Surodina I V 
Published: December 2021

Abstract
The southern site is located in the junction zone of the Southwestern and Eshtykel bench, where vertical electrical soundings were performed, and a preliminary fault-block depth model was built based on the results of field data interpretation using a horizontally layered model. Comparison of geoelectric and seismological data showed that the epicenters of significant earthquakes (M> 4) are concentrated in the identified faults. In the central site, three profiles of electrotomography were made through a bench, well expressed in the relief. Three-dimensional modeling was used to verify and clarify the structural features of both sections. Modeling is performed using programs EMF_DC3Dmod (GPU) - an accelerated version of the program EMF_DC3Dmod for vertical electrical sounding and SCALA-48 (GPU) for the method of electrotomography. The study is relevant for the tasks of geodynamics, seismic zoning and seismic hazard assessment.
Applying the R-solution method for designing a tsunami observational system
Authors: Voronina T A , Loskutov A V 
Published: December 2021

Abstract
One of the promising methods of the early warning of a tsunami is obtaining data of the wave heights based on the numerical solution of the inverse tsunami problem by using the truncated singular value decomposition method as a variant of the least-squares method. The problem is considered within the framework of the linear theory of wave propagation. The technique proposed allows one to avoid the inevitable instability of the numerical solution. It is possible to choose the most informative directions for the placement of the observation stations, which is based on the analysis of the energy transfer by the spatial modes generated by each right singular vector. As it has turned out, the best location of the stations is closely related to the directions of the most intense distribution of the tsunami energy. One of the significant advantages of the approach presented is the possibility, without additional calculations of the tsunami wave propagation from a reconstructed source, to obtain the tsunami wave heights at the points at which there are no observations but which are associated when calculating the matrix of the direct problem operator. The implementation of the approach proposed of the actual event of the Chilean Illapel Tsunami of September 16, 2015, is presented.
Numerical modeling of boundary value problems for differential equations with random coefficients
Authors: Dobronets B S , Popova O A , Merko A M 
Published: December 2021

Abstract
This paper deals with the numerical modeling of differential equations with coefficients in the form of random fields. Using the Karhunen-Lo´eve expansion, we approximate these coefficients as a sum of independent random variables and real functions. This allows us to use the computational probabilistic analysis. In particular, we apply the technique of probabilistic extensions to construct the probability density functions of the processes under study. As a result, we present a comparison of our approach with Monte Carlo method in terms of the number of operations and demonstrate the results of numerical experiments for boundary value problems for differential equations of the elliptic type.
Vector autoregression process. Stationarity and simulation
Authors: Tovstik T M 
Published: December 2021

Abstract
For vector discrete-parameter random autoregressive processes and for a mixed autoregression/moving-average model, we obtain conditions which should be satisfied by the correlation functions or the model coefficients in order that the process be weakly stationary. Fairly simple tests are used. Algorithms for modeling such vector stationary processes are given. Examples are presented clarifying testing criteria for stationarity of models defned in terms of the coefficients or the correlation functions of the process.
Recent increase in the observation-derived land evapotranspiration due to global warming
Authors: Wang Ren , Li Longhui , Gentine Pierre , Zhang Yao , Chen Jianyao , Chen Xingwei , Chen Lijuan , Ning Liang , Yuan Linwang , Lü Guonian 
Published: December 2021

Abstract
Estimates of change in global land evapotranspiration (ET) are necessary for understanding the terrestrial hydrological cycle under changing environments. However, large uncertainties still exist in our estimates, mostly related to the uncertainties in upscaling in situ observations to large scale under non-stationary surface conditions. Here, we use machine learning models, artificial neural network and random forest informed by ground observations and atmospheric boundary layer theory, to retrieve consistent global long-term latent heat flux (ET in energy units) and sensible heat flux over recent decades. This study demonstrates that recent global land ET has increased significantly and that the main driver for the increased ET is increasing temperature. Moreover, the results suggest that the increasing ET is mostly in humid regions such as the tropics. These observation-driven findings are consistent with the idea that ET would increase with climate warming. Our study has important implications in providing constraints for ET and in understanding terrestrial water cycles in changing environments.
The role of anticipatory humanitarian action to reduce disaster displacement
Authors: Thalheimer Lisa , Simperingham Ezekiel , Jjemba Eddie Wasswa 
Published: December 2021

Abstract
Displacement due to weather and climate-related events (disaster displacement), including the adverse effects of climate change, is one of the greatest humanitarian challenges of the 21st century. Even though the forecasting of extreme events and early warning systems has improved globally, less attention has been given to translating anticipatory humanitarian action into the disaster displacement context with the aim to minimize forced displacement from extreme weather events through pre-allocated funds for the readiness, pre-positioning and activation costs. In this analysis, we assess the opportunities and challenges associated with utilising forecast-based financing (FbF) to expand anticipatory and early humanitarian action, based on the structured judgements of experts. These multi-disciplinary experts agree that FbF can reduce displacement risks and address the humanitarian impacts of disaster displacement early, or before a hazard materializes. We propose four action steps along the stages of disaster displacement to provide practical intervention points for researchers and practitioners. Finally, we discuss the implications of our findings and outline next steps. By integrating cross-disciplinary expert judgement, this paper provides a much-needed pathway to transform humanitarian action to be more anticipatory and adaptable to change, and help minimize disaster displacement in climate change vulnerable regions.
Homogeneous Euler equation: blow-ups, gradient catastrophes and singularity of mappings
Authors: Konopelchenko B G , Ortenzi G 
Published: December 2021

Abstract
The paper is devoted to the analysis of the blow-ups of derivatives, gradient catastrophes (GCs) and dynamics of mappings of

R

n

→

R

n

associated with the n-dimensional homogeneous Euler equation. Several characteristic features of the multi-dimensional case (n > 1) are described. Existence or nonexistence of blow-ups in different dimensions, boundness of certain linear combinations of blow-up derivatives and the first occurrence of the GC are among of them. It is shown that the potential solutions of the Euler equations exhibit blow-up derivatives in any dimension n. Several concrete examples in two- and three-dimensional cases are analysed. Properties of

R

u

̲

n

→

R

x

̲

n

mappings defined by the hodograph equations are studied, including appearance and disappearance of their singularities.
Critical points of the random cluster model with Newman–Ziff sampling
Authors: Bell Tolson H , Cockerham Jerrell M , Mizgerd Clayton M , Wiles Melita F , Scullard Christian R 
Published: December 2021

Abstract
We present a method for computing transition points of the random cluster model using a generalization of the Newman–Ziff algorithm, a celebrated technique in numerical percolation, to the random cluster model. The new method is straightforward to implement and works for real cluster weight q > 0. Furthermore, results for an arbitrary number of values of q can be found at once within a single simulation. Because the algorithm used to sweep through bond configurations is identical to that of Newman and Ziff, which was conceived for percolation, the method loses accuracy for large lattices when q > 1. However, by sampling the critical polynomial, accurate estimates of critical points in two dimensions can be found using relatively small lattice sizes, which we demonstrate here by computing critical points for non-integer values of q on the square lattice, to compare with the exact solution, and on the unsolved non-planar square matching lattice. The latter results would be much more difficult to obtain using other techniques.
Physical and Mechanical Properties of Natural Fiber Polyester Laminate Composites
Authors: Ismadi  , Munawar S S , Kusumah S S , Subiyanto B , Purnomo D , Akbar F , Syahrir A 
Published: December 2021

Abstract
The utilization of natural fibers as reinforcing composites has been widely used. Indonesia has natural fibers abundantly such as ijuk fiber (Arenga pinnata), sisal fiber (Agave Sisalana) and coconut fiber (Cocos Nucifera). Random orientation application of the fiber in composites affected to the lower properties. Therefore, the particular orientation of fibres wereapplied in manufacturing of composite by laminating the short fiber with Polyurethane (PU) adhesive. The size and moisture content (MC) of fiber were 14-15 cm and +10%, respectively. The resin content of PU was 5% by weight of the laminate sheet. The mixture of fibers and PU adhesive was cold pressed for 5 minutes with a thickness of 0.5-1 mm. The laminate sheet of PU-adhesive fibers then mixed with unsaturated polyester resin layer by layer. The fiber laminate composition of composite was varieted such as 1, 2 and 3 layers. The hand layup method was used in the manufacturing of the composite. The physical and mechanical testing like density, moisture content, water absorption, thickness swelling, flexural test (adapt to ASTM D 790 standard) and tensile test (adapt to ASTM D 638 standard) were carried out. In additionmorphological analyses were investigated on composite samples. The results research showed that the net density of polyester, ijuk fiber sheet, sisal fiber sheet, and coconut fiber sheet were 1.21, 0.9, 0.53 and 0.22 g/cm3. The range of composite density was 0.99-1.15 g/cm3. The single layer composite had lower thickness swelling and water absorption than those of the three layers composite. The highest tensile strength of three layers of sisal fiber composite was higher (33.84 MPa) than that of the three layers of coconut fiber composite (12.04 MPa). The flexural strength of double layers composite from fiber sisal was higher (63.16 MPa) than that of three layers coconut fiber composite (28.65 MPa).
Cross-species bamboo grading based on flexural properties
Authors: Nugroho N , Kartini  , Bahtiar E T 
Published: December 2021

AbstractThis experiment studied five species of bamboo culms [e.g.B. vulgaris(ampel),D. asper(betung),G. apus(tali),G. atroviolacea(hitam), andG. pseudoarundinaceae(andong)], then analyzed the possibility to develop cross-species bamboo structural grading (both strength and capacity grading) models by mean of dummy variable regression. Since the regression analysis resulted the significantly different coefficient values of the dummy variables, any coincided trendline did not found, but some parallel ones were obtained. The non-coincided but parallel trendlines indicated that a linear equation can estimate the average value of the grade determining property (GDP) of cross-species bamboo structural grading, while the constants must be added to consider the species influence. Meanwhile the non-parallel trendlines indicated that the different linear equation must be applied for every bamboo species. The crossspecies bamboo structural grading could not reliably justify in this study. Species have a strong influence on bamboo grading. Therefore, the authors suggest considering the species identification in the bamboo structural grading.
The Resistance of Heat-Modified Fast Growing Woods Against Decay Fungi
Authors: Priadi T , Suhailiyah W , Karlinasari L 
Published: December 2021

AbstractFast growing woods from plantations forest generally have low quality and require improvement to resist degrading organisms. This study aimed to evaluate the resistance of heat-modified sengon, jabon, mangium, and short rotation teak woods against decay fungi. Heat treatment was applied at two different temperatures (150 °C and 180 °C) and for three different times (0, 2, and 6 hours). The decay resistance test used white rot(Schizophyllum communeFr) and brown rot(Tyromyces palustris)fungibased on modified SNI 01-7207-2014 standard. The chemical analysis of heat-modified wood used Gas Chromatography-Mass Spectrometry. The results showed that the white rot fungal resistance was significantly affected by the interaction of wood species, temperature and period of heating, while the brown rot fungal resistance was significantly affected by the interaction of wood species and heating temperature. Heating at 180 °C for 6 hours increased the fungal resistance of sengon, jabon and mangium woods. However, the fungal resistance of teak wood improved by heating at 150 °C for 6 hours. The durability improvement of the heat-modified woods were suspected due to the appearance or increase of antifungal substances such as benzoic acid, sinapaldehyde, vanillin and 2-methylantraquinone.
The Resistance of Modified Manii Wood with Boric acid and Chitosan/Glycerol and Heating Against Fungi and Termites
Authors: Istriana N , Priadi T 
Published: December 2021

AbstractManii wood (Maesopsiss eminiiEngl.) is a fast grown species that has low durability (class IV) and requires preservation. Boric acid is generally used in wood preservation. However, its application needs to be combined with other treatments to prevent from leaching. This study aimed to evaluate the resistance of manii wood after double impregnation of boric acid and chitosan or glycerol and heat treatment. Heating temperatures were 70ºC and 140ºC. The durability test was carried out against white rot fungus (Schizophyllum commune), dry wood termites (Cryptotermes cynocephalus), subterranean termites (Coptotermes curvignathus) according to SNI 7207-2014 standard, and field test based on ASTM D 1758-08 standard. The retention of boric acid in manii wood was 15,2 ± 1,0 kg ma−3. The interaction of boric acid and chitosan/glycerol impregnations and heat treatment significantly affected the wood resistance against decay fungi and termites. Impregnation of boric acid and glycerol by heating at 140ºC increased the resistance of wood against dry wood and subterranean termites. Double impregnation of boric acid and chitosan followed by heating at 140ºC was the best treatment in this research that improved significantly the resistance of manii wood against white rot fungi, dry wood termites and subterranean termites.