bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimal spacecraft asymptotic velocity for the high inclined orbits formation using gravity assists in the planetary systems
Authors: Grushevskii Alexey , Golubev Yury , Koryanov Victor , Tuchin Andrey , Tuchin Denis 
Published: February 2021

Abstract
The inclination changing of the celestial bodies’ orbits is one of the most energy-consuming procedures. Nevertheless, for a number of promising space projects, leaving the main plane of the planetary or satellite system is fundamentally necessary and demanded. In this case only the possibility of realizing the formation of maximally inclined spacecraft (SC) orbits using gravity assist maneuvers (GM) is remained. However, the dynamic possibilities of GM using are also limited. The maximum possible value of the SC orbital inclination (which gives the extreme point inclination pole – IncPole) depends on the modulus V
inf of the SC asymptotic velocity on the flyby hyperbola and is directly proportional to it (GM geometric limitation). However, the magnitude of the change in inclination at one GM is inversely proportional to V
inf (GM dynamic limitation). As a result, a compromise value of V
inf is existing, which varies for each specific case of the flyby planet. Since in order to achieve a significant inclination a whole series of GMs may be required, in addition, each GM must ensure the “resonance” of the orbital periods of the planet and SC after the GM in order to guarantee their new meeting. According the Jacobi integral in the restricted three body problem the V
inf is an invariant during in all interplanetary flights using GMs. It’s possible to construct the series of increasing GM in form of “jumps” along the

V

inf
⁡

r
e
s

resonance levels from the initial inclination to the maximum possible point IncPole. This point may not belong to any isoline of one of the main resonances itself in the general case. This reduces the GMs effectiveness and necessarily increases the mission time of flight. A heuristic consideration consists in choosing (in the “resonant tuning”) the such value of the design V
inf, which ensures the localization of the inclination pole in the vicinity of some resonance curves between the orbital periods of the spacecraft and the planet (resonant

V

inf
⁡

r
e
s

). Thus it is possible to get to the IncPole by jumping along the resonance curve thru the minimum amount of GM. The paper describes the

V

inf
⁡

r
e
s

formulas and gives its estimates for the Solar system and for the planets satellite systems.
On Abrupt Changes of the Approximate and Sample Entropy Values in Supercomputer Power Consumption
Authors: Tomčala Jiří 
Published: February 2021

Abstract
When calculating the Approximate Entropy (ApEn) and the Sample Entropy (SampEn) of a time series, representing the course of supercomputer power consumption, seemingly unexplained abrupt changes sometimes appear. These sudden changes occur when calculating the course of ApEn and SampEn values using a floating time window and can be manifested also in other discrete-valued time series, such as the development of prices on stock exchanges, time series from birth-death models, count-data time series, etc. These abrupt changes are not continuous and it is clear that they do not reflect real changes in the complexity degree of the analyzed time series. This can cause erroneous detection of a change in the degree of complexity of the time series, which can trigger a false alarm that something unusual is happening in the complex system being monitored (human brain, engine gearbox, financial market, supercomputer infrastructure, etc.). This work reveals in detail the mechanism of this phenomenon and also proposes measures to prevent its occurrence.
Exploring the exact differential equations with GeoGebra software
Authors: Funes Jorge Olivares , Valero Kari Elvis R. 
Published: February 2021

Abstract
In this paper, we will show the solutions of certain exact differential equations that are obtained through the interactive GeoGebra software. GeoGebra software has been of great motivational support in the processes of teaching and modeling in mathematics in various universities and colleges, especially in the engineering careers of the University of Antofagasta in the courses of differential equations and calculation of several variables
First-order linear partial differential equations using the GeoGebra and GeoGebra 3D graphing calculator
Authors: Funes Jorge Olivares , Martin Pablo , Valero Kari Elvis R. 
Published: February 2021

Abstract
In this paper we will show, through various examples of how are the animated solutions of certain linear partial differential equations of the first order with constant homogeneous coefficients through GeoGebra applets designed for a first course of Partial Differential Equations for the engineering careers of the University of Antofagasta-Chile
Bifurcation diagram of stationary solutions of the 2D Kuramoto-Sivashinsky equation in periodic domains.
Authors: Evstigneev Nikolay M. , Ryabkov Oleg I. 
Published: February 2021

AbstractThe solution tree of the 2D stationary Kuramoto-Sivashinsky equations in the periodic domain is analized using the analytical and numerical methods. The evolution of stationary solutions is considered by constructing the bifurcation diagram. Some bifurcation points on the main solution are found analytically, where secondary bifurcations are analized numerically. The bifurcation diagram is constructed using the deflated pseudo arc-length continuation process that allows one to find both connected and disconnected branches of solutions. The resulting bifurcation diagram is analized and subdivided according to characteristic properties of the solution. Different solution branches are visualized in the physical space.
Spatiotemporal localizations of light in quadratically nonlinear media with transversal inhomogeneity
Authors: Chuprikov Ivan , Kalinovich Aleksey , Komissarova Maria , Sazonov Sergey , Zakharova Irina 
Published: February 2021

Abstract
In the current study with the help of mathematical modeling we investigate the generation of second optical harmonic provided various group velocity dispersion (GVD) and third order dispersion effects taken into account. Varying values and signs of the third-order dispersion at quasi-zero values of GVD we reveal the conditions of light bullet formation and stable propagation. To this end we use a generalization of the well-known system of the second harmonic generation in quasi-optical approach. Particular attention is paid to the case when GVD at the second harmonic is close to zero. In addition, we investigate these cases using both focusing and defocusing waveguide which means the presence of transversal inhomogeneity.
Modeling a calibrator for laser interferometer gravitational wave detectors
Authors: Frajuca C , Bortoli F S , Prado A. R. , Magalhaes N. S. , Da Silva W. C. , Souza R. C. 
Published: February 2021

Abstract
Laser Interferometers Gravitational Wave detectors have more than 100 active attenuator systems, the normal methods for calibration seems to not work properly. This work aims to model a calibrator for this detector in the form of a resonant-mass Nb gravitational detector thar has the same sensitivity of LIGO detector bur operating in a narrow band. This detector will detect the same gravitational wave and use this signal to calibrate LIGO. A simulation in a lumped model is made and it shows that the calibration is achievable.
Design of comb-based decimation filter with low power consumption, increased alias rejection and decreased passband droop
Authors: Fernandez De Lara Sosa A , Jovanovic Dolecek G , Salguero Luna S 
Published: February 2021

Abstract
This paper presents design of a low power comb-based decimation filter for decimation of 100. The proposed structure is composed of two stages. The first and second stages are decimated by 4 and 25, respectively. The first stage is a non-recursive structure composed of two cosine filters each decimated by 2. The second stage is a Cascaded-Integrator-Comb (CIC) structure, decimated by 25. Since CIC structure is moved to lower rate, we get a low power structure. The alias rejection is improved increasing the number of cascaded filters by 1 or 2, at second stage. The passband droop is decreased by introducing the compensator at lower rate, i.e. after downsampling by 100. The parameters of compensator are obtained using method of intervals.
STOCHASTIC SIMULATION TO PROJECT SUPPLY OF THE KAZAKHSTAN GENERAL PRACTICE WORKFORCE TO 2030
Authors: Koichubekov Berik , Kharin Azamat , Sorokina Marina , Korshukov Ilya , Omarkulov Bauyrzhan , Ukubayev Temirlan 
Published: February 2021

Abstract
Our aim was to explore the effect of the uncertainty of some parameters on total General Practitioner (GP) supply in Kazakhstan to 2030. System dynamics simulation was used to develop model for General Practitioner workforce forecasting. Sensitivity analysis (Monte Carlo method) was performed to account for changes in the number of GP as each and set of model parameters is varied. Three key input parameters were explored: retirement rate, attrition rate, recruitment rate. For each parameter relative sensitivity was calculated. Created model is the least sensitive to the parameter of the retirement rate, but is very sensitive to attrition rate. Staff turnover is one of the main problems of primary health care. The attrition rate parameter has great potential for controlling the flow of labor. The level of recruitment (other than new GPs) is another factor that has a significant impact on forecasting GPs. The sensitivity to this parameter is comparable to the sensitivity to the rate of depletion. We believe that measures taken to reduce dropouts will simultaneously increase recruitment. We also evaluated the effect of all three parameters simultaneously. If the most likely scenario is realized, then the proposal of a General Practitioner will almost completely cover the needs with a small deficit of 68 to 305 doctors. If the high limit or low limit scenarios in the labor market are implemented, Healthcare Ministry will face serious problems.
Modelling militantism and partisanship spread in the chain and square lattice opinion structures by using q-XY opinion model
Authors: Prenga Dode , Kushta Elmira , Ifti Margarita 
Published: February 2021

Abstract
In this work we have studied the spreading of militantism in 1D and 2D square lattice by operating the q-XY opinion and its utility optimization as control mechanism for the update process. The average utility and opinion value for a pair of opinion nodes are calculated in the framework of standard statistical mechanics using the q-opinion utility

U
=
−

J

2

(

O

→

2

−
2
)

−

F
O

→

+
q

(

J

2

(

O

→

2

−
2
)

∗

F
O

→

)

. The agreement with an incoming zealot opinion is modelled as one by one dialogue starting from a random opinion configuration. Each time step one node updates its opinion value according to a set of rules and by specific probabilities based on local utility improvement. New opinion values are accepted with a Metropolis-like probability calculated by employing q-utilities of the nodes under updating process. For the chain opinion structure in the interaction type preserving regimes where

1
−
q

J

2

(

O

→

2

−
2
)

>
0

given 0 ≤ O ≤ 1 it resulted that that both 1D and 2D structures accept the militant offer only partially. For bounded chain the agreement level is at average values for short chain and low values for bounded long opinion chain. Bounded chain structures are found resistant toward militantism accommodation. For square opinion lattices we obtained also that the militant attitude would never cover all the community. Homogenous-nodes group resulted somewhat deterring in accepting the militant opinion with an agreement level of around 0.6. For heterogonous communities the edge agreement level closed up to around 0.7-0.8. The model reproduces the fact that there would be always a fraction of opposition whatsoever regime is applied. It produces various outcomes imitating the complexity of the social behaviour.
Numerical Modelling of the Draught Rate in a Mechanically Ventilated Climate Chamber
Authors: Angelova R A , Mijorski S , Markov D , Stankov P , Velichkova R , Simova I 
Published: February 2021

Abstract
The thermal environment in an indoor space is determined by the thermal state of the human body, and the local thermal discomfort. The draught rate (DR) is one of the indices for thermal discomfort. The achievement of air distribution without draught is one of the goals of the ventilation methods. It is especially important in the design of climate chambers, where the volume is small, and the research studies may require prolonged occupants’ exposure. Our study shows results from the CFD simulations of a mechanically ventilated climate chamber, performed in the design stage of the chamber’s construction. Velocity profiles distribution, temperature distribution and DR are used to assess the thermal comfort of the person in the chamber. The results obtained allowed designing of the proper indoor environment with desired characteristics for air distribution and human exposure.
Model of the spectral dependence of changes in the polarization state of laser radiation in magneto-optical crystal in the presence of multiple reflections from its faces
Authors: Seleznev A V , Rodionov D A , Kovalenko N V , Shaidullin R I , Ryabushkin O A 
Published: February 2021

Abstract
In this work we investigated the phenomena in the Faraday rotator that can affect the polarization state of transmitting laser radiation. We have found that multiple reflections of radiation from the faces of the terbium gallium garnet (TGG) crystal can cause deterioration of radiation extinction ratio and, therefore, isolation properties of Faraday cell. We were able to calculate the impact of this factor on polarization extinction ratio of monochromatic and quasimonochromatic laser radiation transmitting through the crystal.
A compact 3-dB coupler with stubs
Authors: Letavin Denis A , Alaev Danil P 
Published: February 2021

Abstract
High wave resistance line and no-load stubs were used as a tool for reducing the area of directional coupler on microwave substrate. Replacement of all λ/4 sections (segments) that are part of the coupler with the described artificial transmission lines allowed to reduce the area of the device by 76,8% (with frequency 1.9 GHz). Mathematical calculation and analysis of devices was made using Cadence AWR DE. The manufactured layout has comparable characteristics with the characteristics obtained for the model in AWR program. Negative aspects of miniaturization are narrowing of the line and increasing losses at the coupler.
Light-front approach to relativistic electrodynamics
Authors: Fiore Gaetano 
Published: February 2021

Abstract
We illustrate how our recent light-front approach simplifies relativistic electrody-namics with an electromagnetic (EM) field F

μν

that is the sum of a (even very intense) plane travelling wave

F

t

μ
ν

(
c
t
−
z
)

and a static part

F

s

μ
ν

(
x
,
y
,
z
)

; it adopts the light-like coordinate ξ = ct – z instead of time t as an independent variable. This can be applied to several cases of extreme acceleration, both in vacuum and in a cold diluted pasma hit by a very short and intense laser pulse (slingshot effect, plasma wave-breaking and lasera wake-field cceleration, etc.)
On the Connection Between Deutsch-Jozsa Algorithm and Bent Functions
Authors: Marinho Eraldo Pereira 
Published: February 2021

Abstract
It is presently shown that the Deutsch-Jozsa algorithm is connected to the concept of bent function. Particularly, it is noticeable that the quantum circuit used to denote the well-known quantum algorithm is by itself the quantum computer that performs the Walsh transform of a Boolean function. Consequently, the output from the Deutsch-Jozsa algorithm when the hidden function is bent corresponds to a flat spectrum of quantum states.
A mathematical model for the description of the electrical conductivity of graphene/polymer nanocomposites
Authors: Öz Yahya 
Published: February 2021

Abstract
The dispersion of nanomaterials such as graphene has a major influence on the electrical conductivity in nanocomposites with a polymer matrix. For the description of this effect a continuum model is presented. Within this model, the percolation threshold is determined. Moreover, a distributional analysis is used for the purpose of taking electron hopping between graphene into account. Hence, interfacial conductivity enhanced by tunneling is also included in this study. Recent measurements of nanocomposites that are used for aerospace applications are compared with the results of the presented model and show good agreement between model and experiment.
Frequency response of a microcantilever immersed in a fluid
Authors: Quiñones Manuel , Camargo Luz Helena , Baquero Hugo Aya 
Published: February 2021

Abstract
The micromechanical systems include devices and technology such as actuators and electronic elements on a micrometric scale. A key piece in the development of these systems are the micro cantilevers, which mechanical and dynamic features allow to design sensors and actuators, among others. However, the dynamic response of a microcantilever is altered when it is immersed in a fluid, such as water or even air. This work presents the physical models that describe the behavior of the microcantilevers in fluids (water and air) through the analysis of finite elements. The results show that the density and viscosity of the fluid alter both the oscillation amplitude of the microcantilever and modify the oscillation frequency. Nevertheless, the behavior of the microcantilever in vacuum and air is quite similar.
Effect of temperature on the energy gap in a superconductivity model using U-centers.
Authors: Apushkinskaya D. , Apushkinskiy E. , Popov B. , Saveliev V. , Sobolevskiy V. , Krukovskya L. 
Published: February 2021

Abstract
According to the theory of U-centers, a strong electron-lattice interaction can lead to the fact that the binding energy of two electrons at certain temperatures is higher than the energy of their Coulomb repulsion and, therefore, the possibility of the formation of Cooper pairs appears. If these pairs move coherently without falling apart, then superconductivity occurs. In this work using the Hubbard Hamiltonian and applying the secondary quantization method, we calculate the temperature dependence of the superconducting gap Δ = Δ(T). A temperature dependence of the HTSC resistance in the normal state demonstrates the features of both semiconductor and metallic behavior. It is known that high-temperature superconductors exhibit such properties only in the normal state. In the work presented now, using mathematical calculations, we discuss the presence of four regions of the HTSC phase diagram T = T(ν), where ν is the relative concentration of U-centers. The formation mechanisms of negative U-centers are not considered here. We only assume that they are present in HTSC.
Recent scaling properties of Bitcoin price returns
Authors: Takaishi T 
Published: February 2021

Abstract
While relevant stylized facts are observed for Bitcoin markets, we find a distinct property for the scaling behavior of the cumulative return distribution. For various assets, the tail index μ of the cumulative return distribution exhibits μ
≈ 3, which is referred to as ”the inverse cubic law.” On the other hand, that of the Bitcoin return is claimed to be μ
≈ 2, which is known as ”the inverse square law.” We investigate the scaling properties using recent Bitcoin data and find that the tail index changes to μ
≈ 3, which is consistent with the inverse cubic law. This suggests that some properties of the Bitcoin market could vary over time. We also investigate the autocorrelation of absolute returns and find that it is described by a power-law with two scaling exponents. By analyzing the absolute returns standardized by the realized volatility, we verify that the Bitcoin return time series is consistent with normal random variables with time-varying volatility.
Stochastic thermostats and temperature expressions
Authors: Samoletov A , Vasiev B 
Published: February 2021

Abstract
Molecular dynamics (MD) is in the core of fundamental research for a range of disciplines in natural sciences and is known for its applications in the design of new functional materials and the drug discovery. MD simulations are performed under certain thermodynamic conditions, typically at fixed temperature and pressure. The thermodynamic variables in the MD are modeled using equations that are called thermostats. Many different thermostats have been proposed. Recently (Samoletov A and Vasiev B 2017 J. Chem. Phys. 147 204106), we have shown that a range of thermostats can be derived in the framework of a unified approach based on the fundamental principles of statistical physics, so that the relevant dynamic schemes are based on the concept of temperature expression (in short, ϑ-expression). However, only a few specific ϑ-expressions have been used so far and reported in the literature. In this paper, we are using a wider set of ϑ-expressions and their mathematical properties that allow us to modify the known and offer new thermostats with improved computational efficiency and ergodicity. We focus on the Nosé-Hoover-Langevin stochastic scheme and extend it with additional temperature control tools. Simultaneous thermostatting of all phase space variables with minimal additional computational costs is an advantage of the modified dynamics.
How many shades of grey? On the proximity of density functional approximation to ab initio method via calculations of electric multipole moments
Authors: Xenides Demetrios , Karamanis Panaghiotis 
Published: February 2021

Abstract
The wide spreading of the application of Density Functional Approximation via its represtnatives, i.e. the Density Functionals (DFs), in almost all the fields of computational chemistry is globally witnessed. Therefore, it is believed that an evaluation of their performance in tedious calculations will offer useful insights to both users and developers. As such calculations we chose the prediction of electric multipole moments of first to fourth order, namely dipole (µ

α

/ea
0), quadrupole

(

Θ

α
β

/
e

a

0

2

)

, octupole

(

Ω

α
β
γ

/
e

a

0

3

)

and hexadecapole

(

Φ

α
β
γ
δ

/
e

a

0

4

)

. Values at both ab initio up to the highly accurate couple cluster with singles and doubles (reference values) as well as different flavors of DFs: hybrid, GGA, double hybrid, long range corrected, including dispersion correction, both hybrid and long range corrected and some from the Minessota family. The target set is a group of 10 molecules of C
2

ν
symmetry. The results were further analyzed with the root mean square deviation (RMSD) method as to find the method that is the most proximal to reference CCSD. The functionals PBE1PBE, CAM-B3LYP and B2PLYP seem to survive the proximity test, whereas B97D, M05, M06 and M08 provide results that are the least proximal to CCSD ones.
Mathematical modeling of elastic wave radiation during infinite screw dislocation bending vibrations
Authors: Dezhin V V 
Published: February 2021

Abstract
In this paper, we consider elastic waves radiation (acoustic emission) by infinite screw dislocation performing small bending vibrations under action of external influences. Braking of the dislocation vibrations by medium was not taken into account. To solve this problem, inverse generalized susceptibility of an infinite screw dislocation is written down. It is found that condition for the emission of elastic waves by a screw dislocation is satisfied for two ranges of wave vector component values along the dislocation line. For average value of energy emitted per unit time per unit length of the screw dislocation, corresponding expressions are obtained. Internal friction caused by radiation losses during bending vibrations of the screw dislocation is found.