bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theory of polarization-averaged core-level molecular-frame photoelectron angular distributions: III. New formula for p- and s-wave interference analogous to Young’s double-slit experiment for core-level photoemission from hetero-diatomic molecules
Authors: Ota F , Yamazaki K , Sébilleau D , Ueda K , Hatada K 
Published: December 2021

Abstract
We present a new variation of Young’s double-slit formula for polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) of hetero-diatomic molecules, which may be used to extract the bond length. So far, empirical analysis of the PA-MFPADs has often been carried out employing Young’s formula in which each of the two atomic centers emits an s-photoelectron wave. The PA-MFPADs, on the other hand, can consist of an interference between the p-wave from the x-ray absorbing atom emitted along the molecular axis and the s-wave scattered by neighboring atom, within the framework of multiple scattering theory. The difference of this p–s wave interference from the commonly used s–s wave interference causes a dramatic change in the interference pattern, especially near the angles perpendicular to the molecular axis. This change involves an additional fringe, urging us to caution when using the conventional Young’s formula for retrieving the bond length. We have derived a new formula analogous to Young’s formula but for the p–s wave interference. The bond lengths retrieved from the PA-MFPADs via the new formula reproduce the original C–O bond lengths used in the reference ab-initio PA-MFPADs within the relative error of 5%. In the high energy regime, this new formula for p–s wave interference converges to the ordinary Young’s formula for the s–s wave interference. We expect it to be used to retrieve the bond length for time-resolved PA-MFPADs instead of the conventional Young’s formula.
Investigation of structural, electronic and thermoelectric properties of two-dimensional graphdiyne/borophene monolayers and hetero-bilayers
Authors: Jalili Seifollah , Pakzadiyan Atena 
Published: December 2021

Abstract
The integration of dissimilar 2D materials is important for nanoelectronic and thermoelectric applications. Among different polymorphs and different bond geometries, borophene and graphdiyne (GDY) are two promising candidates for these applications. In the present paper, we have studied hetero-bilayers comprising graphdiyne–borophene (GDY–BS) sheets. Three structural models, namely S0, S1 and S2 have been used for borophene sheets. The optimum interlayer distance for the hetero-bilayers was obtained through binding energy calculations. Then, the structure and electronic properties of the monolayers and hetero-bilayers were individually examined and compared. GDY monolayer was shown to be a semiconductor with a band gap of 0.43 eV, while the borophene monolayers, as well as all studied hetero-bilayers showed metallic behavior. The thermoelectric properties of borophene and GDY monolayers and the GDY–BS bilayers were calculated on the basis of the semi-classical Boltzmann theory. The results showed signs of improvement in the conductivity behavior of the hetero-bilayers. Furthermore, considering the increase in Seebeck coefficient and the conductivity for all the structures after calculating figure of merit and power factor, a higher power factor and more energy generation were observed for bilayers. These results show that the GDY–BS hetero-bilayers can positively affect the performance of thermoelectric devices.
Formation and dissociation of shear-induced high-energy dislocations: insight from molecular dynamics simulations
Authors: Chen Nanjun , Hu Shenyang , Setyawan Wahyu , Gwalani Bharat , Sushko Peter V , Mathaudhu Suveen N 
Published: December 2021

Abstract
Solid-phase processing (SPP) allows one to create complex microstructures, not achievable via thermal processing alone. The resulting structures exhibit a rich palette of defects, both thermal and non-thermal, including defect substructures, such as dislocation networks. It is essential to understand the mechanisms of deformation and defect structure formation to guide SPP towards achieving desired microstructures and material properties. In this study, large-scale molecular dynamics simulations are used to investigate the effects of inhomogeneous strain distribution, that mimics deformation conditions of tribological tests, on the evolution of defects under severe shear deformation in polycrystalline Al. Analysis of defect nucleation and reaction pathways reveals that strong geometric constraints suppress the nucleation and slide of low energy dislocation 1/2⟨110⟩{111} but promote the nucleation and slide of high energy dislocations, such as

1

1

¯

0

(001) and 1/2

1

1

¯

2

¯

(1

1

¯

1). A rough contact surface, characteristic to tribological tests, imposes an inhomogeneous stress field leading to inhomogeneous defect substructures due to location-dependent activation of slip systems. The results suggest that high-energy dislocations can dominate the evolution of grain structures in highly constrained environments, which should be considered in modeling plastic deformation and grain refinement during SPP.
Impact of a strong temperature gradient on grain growth in films
Authors: Zöllner D 
Published: December 2021

Abstract
The migration of grain boundaries and, therewith, the phenomenon of grain growth depend strongly on the annealing temperature. Generally, higher temperatures are associated with higher mobilities of the boundaries and therewith faster microstructural coarsening. In the present study, the influence of a strong temperature gradient on grain growth in thin films is investigated. To that aim, a modified three-dimensional Potts model algorithm is employed, where the annealing temperature changes with the thickness of the sample taking grain boundary mobility and energy into account. The resulting drag effect has serious consequences for the temporal and spatial evolution of the grain microstructure.
Wafer-scale plasmonic metal–dielectric–metal structural color featuring high saturation and low angular dependence
Authors: Huang Yudie , Lv Fanzhou , Chen Jiaxu , He Shijia , Wang Zhihang , La Junqiao , Wu Dongda , Cong Rong , Wang Yi , Wang Wenxin 
Published: December 2021

Abstract
Structural color has been studied through various methods due to its distinguished features of stability, durability, high information storage density and high integration. However, the artificial structural color samples do not exhibit superior performance in color saturation and low angular dependence. Here, we present an approach to acquire additive reflective color based on a metal–dielectric–metal (MDM) stack. The upper layer composed of Ag particles is perforated in a hexagonal arrangement which profits from the dielectric anodic aluminium oxide (AAO) membrane. The size and shape of the Ag particles are getting inhomogeneous as the deposition thickness of the upper layer increasing, which expands the desired absorption range of surface plasmons. The residual non-anodized Al foil serves as a highly reflective substrate for efficient color presenting through the thin-film interference in this plasmonic MDM system. As a result, the color gamut area of this MDM stack is extended 8 times in CIE chromaticity coordinates. Finally, a wafer-scale (diameter of 83 mm) badge of Harbin Engineering University (HEU) with highly saturated colors and a pattern characterized with low angle-dependent property (up to 60°) are presented, which exhibit promising prospects in commercial coloring and imaging.
Leakage mechanism in Al
x
Ga1−x
N/GaN heterostructures with AlN interlayer
Authors: Köhler Klaus , Pletschen Wilfried , Kirste Lutz , Leone Stefano , Müller Stefan , Aidam Rolf , Bronner Wolfgang , Brückner Peter , Waltereit Patrick , Polyakov Vladimir , Ambacher Oliver 
Published: December 2021

Abstract
Leakage of Al
x
Ga1−x
N/GaN heterostructures was investigated by admittance–voltage profiling. Nominally undoped structures were grown by low-pressure metal-organic vapor-phase epitaxy. The investigated structures had an Al-content of 30%. They are compared to structures with an additional 1 nm thick AlN interlayer placed before the Al0.3Ga0.7N layer growth, originally to improve device performance. Conductance of field effect transistor devices with AlN interlayer, measured from depletion of the two-dimensional electron gas (2DEG) to zero volt bias at frequencies ranging from 50 Hz to 10 kHz, could be described by free charge carriers using a Drude model. The voltage dependent conductance shows a behavior described by either Poole-Frenkel emission or Schottky emission (SE). From the size of the conductance, as well as simulation of the tunneling current injected from the gate under off-state conditions by universal Schottky tunneling, SE is obvious. Evaluating the data by SE, we can locate the leakage path, of tens of nm in the range between gate and drain/source with contact to the 2DEG, originating from the AlN interlayer. The static dielectric constant in growth direction, necessary for the evaluation, is determined from various Al
x
Ga1−x
N/GaN heterostructures to ϵ
||(0) = 10.7 ± 0.1.
Phantom-like dark energy from quantum gravity
Authors: Oriti Daniele , Pang Xiankai 
Published: December 2021

Abstract
We analyse the emergent cosmological dynamics corresponding to the mean field hydrodynamics of quantum gravity condensates, in the group field theory formalism. We focus in particular on the cosmological effects of fundamental interactions, and on the contributions from different quantum geometric modes. The general consequence of such interactions is to produce an accelerated expansion of the universe, which can happen both at early times, after the quantum bounce predicted by the model, and at late times. Our main result is that, while this fails to give a compelling inflationary scenario in the early universe, it produces naturally a phantom-like dark energy dynamics at late times, compatible with cosmological observations. By recasting the emergent cosmological dynamics in terms of an effective equation of state, we show that it can generically cross the phantom divide, purely out of quantum gravity effects without the need of any additional phantom matter. Furthermore, we show that the dynamics avoids any Big Rip singularity, approaching instead a de Sitter universe asymptotically.
On an application of the Boundary control method to classical moment problems.
Authors: Mikhaylov A S , Mikhaylov V S 
Published: December 2021

Abstract
We establish relationships between the classical moments problems which are problems of a construction of a measure supported on a real line, on a half-line or on an interval from prescribed set of moments with the Boundary control approach to a dynamic inverse problem for a dynamical system with discrete time associated with Jacobi matrices. We show that the solution of corresponding truncated moment problems is equivalent to solving some generalized spectral problems.
Stability estimation of the generalized solution to the direct problem for the acoustic equation
Authors: Kabanikhin Sergey , Nurseitova Altyn , Kasenov Syrym 
Published: December 2021

AbstractThe initial-boundary value problem for the acoustic equation with data on a timelike surface is considered in this paper. Such a problem arises, for example, if it is required to determine the acoustic pressure inside the region from a fixed response to part of the boundary from the source involved at the same boundary. It is assumed that the medium is at rest up to a certain instant of time and the parameters of the medium, for example, acoustic density, are known. The problem is considered in a triangular domain. The advisability of this was shown in the second half of the last century in the works of Romanov V.G. (for example, [1]), where it was proved that the solution to the direct problem of acoustic is representable as the sum of a singular and a continuous terms. The author has written out the form of the singular part, investigated the problem in an integral statement, and also proved conditional well-posedness theorems for three cases: for a small parameter of the domain, for small data, and for the source representability of the sought solution. It is known that the initial-boundary value problem for the acoustic equation with data on a timelike surface is ill-posed. In this paper, the original ill-posed problem is reduced to an inverse problem with respect to some direct (well-posed) problem. The theorem is proved and a stability estimate of the generalized solution to the direct problem is obtained.
A minimization problem for the sum of weighted convolutions’ difference and a novel approach to the inverse problem of ECG- and PPG-signals recovering
Authors: Kel’manov A , Khamidullin S , Mikhailova L , Ruzankin P 
Published: December 2021

Abstract
In this paper, we consider an unstudied problem of approximation of an observed pulse train by by a quasiperiodic signal generated by a pulse with a given pattern (reference) shape. The quasiperiodicity allows variation of time intervals between repetitions of the pattern pulse, as well as nonlinear expansions of the pattern in time. Such inverse problems are common in electrocardiogram (ECG) and photoplethysmogram (PPG) features extraction. The following two variants of the problem are considered. In the first variant, the number of the pulse repetitions is unknown, while in the second one, that number is given. The polynomial-time solvability of the both variants of the problem is constructively proved.
On the existence and uniqueness of the solution of the coefficient inverse problem for a semilinear parabolic equation
Authors: Sugezhik A L 
Published: December 2021

Abstract
In this paper, we consider the problem of determining the source function and the coefficient by the derivative with respect to time in a semilinear parabolic equation with overdetermination conditions defined on two different hyperplanes. The existence and uniqueness theorems of the classical solution of the posed coefficient inverse problem in the class of smooth bounded functions were proved. An example of input data satisfying the conditions of the proved theorems is given.
Comparative analysis of numerical methods for determining parameters of chemical reactions from experimental data
Authors: Prikhodko Aleksei , Shishlenin Maxim , Stadnichenko Olga 
Published: December 2021

Abstract
The aim of this paper is to select an optimal numerical method for determining the parameters of chemical reactions. The importance of the topic is due to the modern needs of industry, such as the improvement of chemical reactors and oil or gas processing. The paper deals with the problem of determining reaction rate constants using gradient methods and stochastic optimization algorithms. To solve an forward problem, implicit methods for solving stiff ODE systems are used. A correlation method of practical identifiability of the required parameters is used. The genetic algorithm, particle swarm method, and fast annealing method are implemented to solve an inverse problem. The gradient method for the solution of the inverse problem is implemented, and a formula for gradient of the functional is given with the corresponding adjoint problem. We apply an identifiability analysis of the unknown coefficients and arrange the coefficients in the order of their identifiability. We show that the best approach is to apply global optimization methods to find the interval of global solution and after that we refine inverse problem solution using gradient approach.
Two optimization methods for solving the inverse gravimetrical problem
Authors: Kenzhebayeva Merey 
Published: December 2021

Abstract
Mineral exploration, in particular, increasing the accuracy of calculations up to now is one of the urgent problems of geophysics. It is necessary to restore the density of a given inhomogeneity after considering the results of measuring the potential and its gradient on the surface of the earth. One of the measured values, the potential or the gradient of the gravity field, is chosen beyond the boundary condition, and the second corresponds to the minimized functional, i.e. one in-verse problem can be put in correspondence two different optimization problems. Both problems are solved based on the same gradient method. Based on the numerical analysis, two methods for solving the inverse problem are compared.
Identification of spacewise dependent right-hand side in two dimensional parabolic equation
Authors: Su LingDe , Vasil’ev V. I. 
Published: December 2021

Abstract
In this paper numerical solution of the inverse problem of determining a spacewise dependent right-hand side function in two dimensional parabolic equation is considered. Usually, the right-hand side function dependent on spatial variable is obtained from measured data of the solution at the final time point. Many mathematical modeling problems in the field of physics and engineering will encounter the inverse problems to identify the right-hand terms. When studying an inverse problem of identifying the spacewise dependent right-hand function, iterative methods are often used. We propose a new conjugate gradient method based on the constructed self-adjoint operator of the equation for numerical solution of the function and numerical examples illustrate the efficiency and accuracy.
Quantity of the inverse problem data for the system of conservation laws
Authors: Klyuchinskiy D.V. , Novikov N.S. , Shishlenin M.A. 
Published: December 2021

Abstract
In this paper we study properties of the model, that describes the plane acoustic waves propagation. The model is based on the hyperboliv system of PDE, which is solved numerically by using the finite-volume method, based on Godunov scheme. After studying the direct problem we turn to the inverse one, where our goal is to recover the parameters of the system of PDE by using the initial data, measured in the receivers. We obtain the formula for the gradient of the misfits functional, which allows us to apply gradient-based optimization for recovering the density of the medium. We present the results of numerical experiments for different number of receivers, thus, studying the influence of the quantity of the data of inverse problem on the accuracy of the solution.
Gelfand-Levitan-Krein method in one-dimensional elasticity inverse problem
Authors: Kabanikhin Sergey I. , Novikov Nikita S. , Shishlenin Maxim A. 
Published: December 2021

AbstractIn this article we propose the numerical solution of the one dimensional inverse coefficient problem for seismic equation. We use a dynamical version of Gelfand-Levitan-Krein approach for reducing a nonlinear inverse problem for recovering the shear wave’s velocity and the density of the medium to two sequences of the linear integral equations. We propose numerical algorithm for solving these equations based on a fast inversion of a Toeplitz matrix. The proposed numerical methods base on the structure of the problem and therefore improve the efficiency of the algorithms, compared with standard approaches. We present numerical results for solving considered integral equations.
Numerical Identification of the Filtration Capacitive Parameters in Two-Phase Petroleum Reservoirs
Authors: Sakabekov A. , Ahmed Zaki D. , Auzhani Y. 
Published: December 2021

Abstract
We study initial and boundary value problem for nonlinear three dimensional two phase nonlinear filtration problem in three dimensional bounded regions. The reservoir is a two phase and three dimensional oil-water system that is been implemented with typical parallelepiped model. The reservoir constructed with different number of grid blocks in x, y and z directions and initialized with initial pressure, water saturation, corresponding fluid and rock properties in every grid block. To find approximate solution of the above mentioned problem we use finite difference method. We form solution’s algorithm of inverse problem for numerical parameter identification of the petroleum reservoir.
Reservoir Parameters Estimation with Some Log Curves of Qiongdongnan Basin Based on LS-SVM Method
Authors: Liu Tangwei , Xu Hehua , Shi Xiaobin , Qiu Xuelin , Sun Zhen 
Published: December 2021

Abstract
Reservoir porosity and permeability are considered as very important parameters in characterizing oil and gas reservoirs. Traditional methods for porosity and permeability prediction are well log and core data analysis to get some regression empirical formulas. However, because of strong non-linear relationship between well log data and core data such as porosity and permeability, usual statistical regression methods are not completely able to provide meaningful estimate results. It is very difficult to measure fine scale porosity and permeability parameters of the reservoir. In this paper, the least square support vector machine (LS-SVM) method is applied to the parameters estimation with well log and core data of Qiongdongnan basin reservoirs. With the log and core exploration data of Qiongdongnan basin, the approach and prediction models of porosity and permeability are constructed and applied. There are several type of log data for the determination of porosity and permeability. These parameters are related with the selected log data. However, a precise analysis and determine of parameters require a combinatorial selection method for different type data. Some curves such as RHOB,CALI,POTA,THOR,GR are selected from all obtained logging curves of a Qiongdongnan basin well to predict porosity. At last we give some permeability prediction results based on LS-SVM method. High precision practice results illustrate the efficiency of LS-SVM method for practical reservoir parameter estimation problems.
Development and modeling of some elements of the two-wheeled mobile robot system
Authors: Karpov Alexander O , Karpov Alexey O , Yu Vasilyeva M , Belashova И E S 
Published: December 2021

Abstract
The article deals with the navigation system elements development process. The movement and positioning of a two-wheeled mobile robot with a high level of accuracy are realized through this system. Also, the algorithms mechanisms based on the construction of the optimal path for the autonomous device movement and based on a map building in an unknown area and avoiding obstacles are described. Using mathematical models, computer modeling of the device executive system is carried out using the engineering program MatLab.
Comparative Analysis of Efficiency of the Machine Learning Methods for Gesture Recognition Using Double-Channel Electromyography
Authors: Ponomarchuk Y V , Kuznetsov I V 
Published: December 2021

Abstract
The paper is devoted to the efficiency analysis of the machine learning methods for gesture recognition, which are applied to the surface double-channel electromyography data. The comparative analysis was conducted for recognition of eight types of palm movements. The results of the analysis lead to conclusion that it is necessary to consider the muscle groups’ location for better recognition accuracy and the increase of the number of considered gestures.