bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reliability-centered maintenance and cost optimization for offshore oil and gas components
Authors: Nithin A H , Sriramula S , Ebinum T 
Published: February 2021

Abstract
Reliability-Centered Maintenance (RCM) is widely used for enterprise asset management in the Oil and Gas sector. The traditional RCM process encompasses the development of equipment hierarchy, the determination of the functional failure of assets, identification of the critical failure modes and the development of suitable maintenance strategies for these failure modes through RCM logic tree analysis. However, the current industry standards and conditions call for greater strides of production availability and reliability of the assets. The aim of the paper is to deliver RCM oriented cost optimization framework for the assets through the implementation of probabilistic and statistical analysis. Probabilistic analysis of the most critical components predicts the failure over time. The mean time to failure, mean time between failure and mean time to repair parameters are determined from the failure history. The parameters of the probability distribution, for instance, the shape and scale parameters of Weibull distribution determine the failure pattern of the failure mode over time. The cost optimization modules allow the analyst to determine the optimum intervals for maintenance or replacement of the maintainable items. The integrated RCM methodology, therefore, provides quantitative and cost-effective solutions for asset maintenance and management. A case study of an equipment in the Oil and Gas sector will be presented to illustrate the optimization framework.
Elasticity index evaluation based on Le Cam divergence and kernel density estimator in PM space
Authors: Kus Vaclav , Dolejs Erik 
Published: February 2021

Abstract
This work focuses on the application of Preisach-Mayergoyz (PM) model applied to the evaluation of elastic properties of hysteretic material. In the first part, essential concepts are explained such as material hysteresis, probability density functions of PM space, optimization algorithm used, and phi-divergence measures applied in the PM identification process. Next, two different characterizations of PM space of hysterons based on kernel density estimators are proposed, either for one-dimensional PM space projection or for fully two-dimensional pyramid kernel. Finally, new index of elasticity is built up by means of the squared Le Cam divergence between probability density corresponding to the super-elastic distribution and the probability density found by our optimized PM identification process, respectively. This elasticity index describes ability of the material to absorb mechanical deformation, or alternatively, it gives an evidence about the certain degree of damage of the material. This proposed index of elasticity (IE) is evaluated for the case of experimental data measured on the steel dampers used for the protection against earthquakes.
Gravitation in the theory of compressible oscillating ether
Authors: Magnitskii Nikolai 
Published: February 2021

Abstract
Previously, the basic laws and equations of electrodynamics, atomic physics, and elementary particles theory were derived from the theory and equations of compressible oscillating ether. In this work, the ethereal theory of gravitation is constructed, the similarities and differences between gravitational and electrostatic fields are explained. It is shown that in gravitation there are no attractive forces, but there are pressing forces, and that the gravitational constant is not really constant, but weakly depends on the chemical composition of interacting bodies. Gravitational interactions between bodies do not propagate from one body to another at a certain speed, and at any moment, the stationary gravitational fields exist with and around the bodies, and therefore neither gravitational waves nor gravitons exist in nature. The values of all parameters of the ether, including the density of its unperturbed state, are found
Numerical analysis of a vibro-impact system with ideal and non-ideal excitation
Authors: Hajradinovic Dzanko , Zukovic Miodrag , Kovacic Ivana 
Published: February 2021

Abstract
This study is concerned with modelling and analyses of a vibro-impact system consisting of a crank-slider mechanism and one oscillator attached to it, where the system can be exposed to ideal or non-ideal excitation. The impact occurs during the motion of the oscillator when it hits a base, and the excitation of the driving source is affected by this behaviour. The aim is to determine the interaction between a driving torque and the motion of the oscillator. To achieve this aim in a methodologically sound manner, both vibro-impact systems with ideal and non-ideal excitation are analysed. For these system differential equations are formed and the impact model is provided in the paper. The impact causes a strong nonlinearity in the system. The mathematical model of the vibro-impact system with ideal excitation is presented as a second order differential equation where the vibro-impact system with non-ideal excitation is given as a coupled system of nonlinear second order differential equations. Numerical simulations are carried out for the two systems and the results obtained are shown in terms of frequency response diagrams as well as in terms of time-displacement diagrams. The results found for different systems are compared mutually, and the differences between them are pointed out. Impact solutions for different regions of the excitation frequency are shown. For a specific value of the excitation frequency in the frequency response diagram where multiple solutions are found, basin of attractor diagrams are formed. Average value of the excitation frequency is used for the vibro-impact system with non-ideal excitation.
Solving an optimal control problem of the robot using the Picard’s method.
Authors: Lounis Abbes , Louadj Kahina , Aidene Mohamed 
Published: February 2021

Abstract
This paper presents an optimal control problem applied to the robot, the problem is to determine a command that allows to reach the final state from the initial state in record time. This problem will be solved by applying The Pontryagin’s Maximum Principle (PMP) combined with Picard’s successive approximation method and shooting method.
Mathematical model of electrical conductivity of biological tissues based on ion electrodiffusion equations
Authors: Kovalenko N V , Sovin K V , Shamankov N O , Ryabushkin O A 
Published: February 2021

Abstract
A method for modeling of the electrical properties of biological tissues is introduced. It is based on the division of tissue in accordance with the geometry of living cells and the solution of the Nernst-Planck electrodiffusion equation for the calculation of ion currents between individual cells.
Modeling a broadband detector for an experiment that measures the speed of gravity over short distances
Authors: Frajuca C , Bortoli F S , Magalhaes N. S. , Da Silva W. C. , Souza R. C. 
Published: February 2021

Abstract
In order to investigate the behavior of gravitational signals while travelling through a medium an experiment was designed, aimed at measuring the speed of these signals over short distances. The experiment contains 2 sapphire devices that behave as a detector, which are suspended in vacuum and cooled down to 4.2 K. The amplitude of the detecting device is measured by an ultralow, phase-noise microwave signal that uses resonance in the whispering gallery modes. Since sapphire has a quite high mechanical Q, the detection band is expected to be small, thus reducing the detection sensitivity. A new shape for the detecting device is presented in this work, yielding a detection band of several hundred Hertz. With the aid of a Finite Element Program the normal mode frequencies of the detector are determined.
Obtaining the predicted number of cycles of femoral prosthesis manufactured with ASTM F138 and ASTM F75 aloys, applying the method of finite element.
Authors: Silva Junior Wilson Carlos Da , Pereira De Souza Caique Movio , Silva Bortoli Fabio Da , Frajuca Carlos , Souza Renato Chaves 
Published: February 2021

Abstract
This study aims to calculate the predictive number of cycles applied to femoral prostheses made with ASTM F138 and ASTM F75 alloys. A hip prosthesis is typically subjected to cyclic loads commensurate with the patient’s weight in response to each step and hence requires a cyclic compression stress approach. Austenitic stainless steels have been used in surgical applications over many years due to low cost, good mechanical properties and resistance to corrosion. The CrCoMo alloy features higher corrosion resistance compared to ASTM F138 stainless steel. In order to perform finite element analysis, two software were used: Autodesk® Inventor® 2013 and Autodesk® Simulation 2015. The formatting of the simulation followed the parameters established in the ISO 7206-4: 2016 ABNT NBR standard, the applied load was 2,3 kN with an angle of 10 degrees with respect to the frontal plane and 9 degrees with respect to the lateral plane. As for the static analysis, the prosthesis composed of ASTM F138 material presented satisfactory results, and the prosthesis made with the ASTM F75 alloy failed. Both prostheses did not exceed 5 million cycles in the dynamic load application.
Anisotropy of glancing angle deposited films: results of atomistic simulation
Authors: Grigoriev F V , Sulimov V B , Tikhonravov A V 
Published: February 2021

Abstract
Anisotropy of SiO2 films fabricated by glancing angle deposition is investigated using the classical atomistic simulation and anisotropic Bruggeman effective medium theory. The voids between the slanted columns, occurring as a result of glancing angle deposition, are considered as ellipsoids. Averaged shape parameters of these ellipsoids are defined using the density gradient tensor. Calculated values of difference of refractive index components of glancing angle deposited SiO2 films are in accordance with experiment.
Predicting entanglement and coherent times in FMO complex using the HEOM method
Authors: González-Soria Bruno , Delgado Francisco , Anaya-Morales Alan 
Published: February 2021

Abstract
Fenna-Matthews-Olson (FMO) bacteriochlorophylls (BChls) are molecules responsible of the high efficiency energy transfer in the photosynthetic process of green sulfur bacteria, controversially associated to quantum phenomena of long lived coherence. This phenomenon is modelled using Quantum Open Systems (QOS) without include memory effects of the surrounding approximated as a phonon bath on thermal equilibrium. This work applies the Hierarchical Equations of Motion method (HEOM), a non-Markovian approach, in the modelling of the system evolution of FMO complex to perform predictions about the coherence times scales together with global and semi-local entanglement during the quantum excitation.
Finsler geometry modeling for anisotropic diffusion in Turing patterns
Authors: Koibuchi Hiroshi , Okumura Masahiko , Noro Shuta 
Published: February 2021

Abstract
Turing patterns are known to be described by diffusion reaction (DR) equations, and the patterns become zebra-like anisotropic if the diffusion constant is directionally dependent. However, the origin of this dependence is unclear. In this study, we report that Turing patterns can be studied with the Finsler geometry (FG) modeling technique by applying a hybrid numerical technique, which combines DR equations and the Monte Carlo (MC) technique. In the DR equations and the Hamiltonian for MC, the Finsler metric is introduced using internal degrees of freedom. We numerically show that anisotropic patterns appear according to a constraint given by some external forces applied to the internal degrees of freedom. In this FG modeling technique, direction-dependent diffusion constants are unnecessary, and these constants automatically or effectively become anisotropic. We consider that the internal degrees of freedom introduced for the Finsler metric play an essential role in the anisotropic patterns.
Finsler geometry modeling of complex fluids: reduction in viscous resistance
Authors: Okumura Masahiko , Homma Ippei , Noro Shuta , Koibuchi Hiroshi 
Published: February 2021

Abstract
Complex fluids refer to a broad range of materials that contain two different phases, such as solid-liquid and fluid-gas mixtures. Generally, in fluids with dispersed matter, the viscous resistance is not always proportional to the velocity of the fluids, and a fluid exhibiting such behavior is called a non-Newtonian fluid. The viscous resistance is considerably decreased in a certain range of velocities compared to the case without macromolecules. This change in the macroscopic viscous resistance is expected to originate from the interactions between fluids and dispersed matter. In this study, we apply the Finsler geometry (FG) modelling technique to implement this complex interaction, and we numerically show a mechanism for the reduction in viscous resistance. In the FG modeling, a new dynamical variable corresponding to the directional degrees of freedom of dispersed matter is introduced and updated by the Monte Carlo simulation technique during iterations of the Navier-Stokes equation. The tentative results indicate that the distribution of the viscous force and its position dependence are considerably different from those in standard Newtonian fluids. This finding indicates the possibility that the FG modeling technique can properly describe the effects of dispersed matter on the flow behavior.
The influence of isoenergy surface anisotropy and surface scattering kinetics on the conductivity of a thin metal layer
Authors: Savenko O V , Romanov D N , Kuznetsova I A 
Published: February 2021

Abstract
A kinetic theory of the conductivity of a thin metal layer in a longitudinal alternative electric field is constructed. We assume the layer thickness is much greater than the electron de Broglie wavelength and less than the skin layer depth. Therefore, the skin effect is neglected and electron energy spectrum quantization is not considered. The Soffer model is used as the boundary conditions for the Boltzmann equation. We suppose the roughness parameters of the upper and lower layer surface have different values. The Fermi surface is an ellipsoid of revolution, the main axis of which lies in the layer plane. The dependences of conductivity tensor components on the layer thickness, electric field frequency, Fermi surface anisotropy parameter, and surface roughness parameters are analyzed. The results are compared with the ones performed within the framework of diffuse-mirror boundary conditions and with experimental data.
Local mean field approximation applied to a 3D spin crossover nanoparticles configuration: free energy analysis of the relative stability of the stationary states
Authors: Cazelles C. , Linares J. , Singh Y. , Dahoo P.-R. , Boukheddaden K. 
Published: February 2021

Abstract
The local mean field approximation is applied to an inhomogeneous 3D spin crossover (SCO) nanoparticle configuration with a special focus on its systemic effect on molecules in the bulk, at the corner, at the edge and at surface. The matrix effect at the surface is introduced through a specific interaction term, L. The partition function for each region allows the determination of the total free-energy F from which the stability of each configuration is analyzed through thermodynamic considerations.
Structural characteristics of gluconolactone/gluconic acid aqueous solution used for bio battery by molecular dynamics
Authors: Matsunaga Shigeki 
Published: February 2021

Abstract
The structural characteristics of gluconolactone/gluconic acid aqueous solution as a model for the anode of biofuel cells are investigated by molecular dynamics. The molecular structure of components of the solution and the atomic charges are optimized by the density functional theory (DFT) using Gaussian09. The distribution of constituent ions of the solution is investigated by a radial distribution function. The shape change of gluconic acid anions in the solution and the frequency distribution of each ion are also examined.
The optimized approach to get the fundamental property of the gravity assists maneuvers from the Jacobi integral
Authors: Grushevskii Alexey , Golubev Yury , Koryanov Victor , Tuchin Andrey , Tuchin Denis 
Published: February 2021

Abstract
The design of interplanetary trajectories using a series of gravity assists maneuvers begins with the ballistic mission design. It is reasonable to construct the corresponding initial approximation using the patched conics method within the model of the circular restricted three-body problem. Such a construction requires the calculation of the “transfer parameter” Vinf
- the dimensionless asymptotic velocity of the spacecraft relative the target planet, when switching from heliocentric arcs to planetocentric segments and vice versa. In the circular restricted three-body problem model, Vinf
can be calculated using the Jacobi integral J (or using it’s analogue - the Tisserand parameter TTiss
and the basic property of the Jacobi integral for the gravity assists maneuvers within the framework of the circular restricted three body problem:
const J ≈ TTISS ≈ 3 – Vinf Vinf
. According to this property, the J value does not change during the multiple gravity assists maneuvers that preserve the Jacobi integral constant are performed. This fact is known in astrodynamics but it is classically derived in a rather cumbersome method. In this study, a shorter method for its obtaining is proposed. The modifications of the representation of the Jacobi integral in the circular restricted three-body problem for the various configurations of three bodies are presented.
The reachable regions construction for the inelastic anisotropic billiards
Authors: Grushevskii Alexey 
Published: February 2021

Abstract
Modern methods of the ballistic design of space flights (entry of a spacecraft with non-zero aerodynamic quality into the planet’s atmosphere, carrying out gravity assist maneuvers around planets) are associated with the need to calculate a lot of trajectories (i.e. of the phase beams). For their effective use and determination of dynamically admissible reachability regions, it is necessary to identify and study the structure of accompanying singularities of the phase parameters and to construct the corresponding adequate and adaptive models. In this sense, the analogy of the motion of these systems with the singular motion of billiard systems turns out to be very fruitful. First of all, we are talking about anisotropic billiards with dissipation taken into account. In this work, we set and described the model problems about the flat stones skipping on the surface of the water (the ricochets) and an inelastic ball analogue which is bouncing or rolling on an imperfect surface in the presence of a side deviation effect. The main indicatrices types classification for the singular reflection from the plane surface is carried out. Model problems of the ricocheting pebble on the surface of the water surface and the inelastic ball bouncing or rolling on an imperfect surface in the presence of a side bouncing effect also the attainability region problem of the atmospheric entry are posed and described. The configurations of their maximum reachable regions are described
The open unsymmetrical stadium billiard
Authors: Espinoza Ortiz J. S. , Lagos-Monaco R. E. 
Published: February 2021

Abstract
In open billiards a particle can escape from the cavity through a leak. This type of systems have received special attention because of their applications to a wide variety of physical phenomena ranging from hydrodynamics to quantum chaos and astronomy. Chaotic leaked billiards are characterized by a so called transient behavior, i.e. by the presence of chaotic motion with a finite life time impossible to be studied just through the analysis of its asymptotic behavior. Under this scenario, we consider the quarter stadium billiard to study the influence of leaking marginal unstable periodic orbits. A rigorous statistical analysis of the survival probability is presented, setting up the classical trajectories’ solution in such a way that the system only depends on its partial separability and construct the Birkhoff map. The possibility of more than one leak into a billiard is also considered
General mathematical model for energetic and informatic evaluated over natively producing surrounded systems
Authors: Zakharov V K 
Published: February 2021

Abstract
Some joint (synthetic) closed in itself idea about the world and its being is expounded in the paper, which gives the opportunity to invent the parallel definitions of the energy and the information not exceeding the bounds of the united world. This allows us to introduce some sufficiently general notion of the evaluated (over natively) producing (transmission stream conservatively-dynamic) surrounded system, described by the proper system of evolutional equations. In the capacity of important partial cases of such systems the proper notions of the energetic evaluated producing surrounded system and the informatic* evaluated producing surrounded system are introduced. The explicitly analyzed earlier examples of the model of heating stove (as the energetic evaluated producing surrounded system) and the model of personal computer (as the informatic evaluated producing surrounded system) expose the applicability of proposed idea to a generalized and formalized description of some wide class of over native systems really existing.
Biophysical parameters affecting lung surfactant function, surface tension and the transition from aerosol to droplet exhalation (in relation to COVID-19 infection)
Authors: Allaerts W 
Published: February 2021

Abstract
A considerable number of biophysical and biochemical studies has increased our understanding of the surface activity of surfactant proteins B and C (SP-B, SP-C) in the (mammalian) lung and their importance for a healthy, proper breathing system. For instance, it is well-known that these surfactant proteins are released from the lamellar bodies of type II cells of the lung alveoli (type II pneumocytes), and that at compression, the lipid-protein monolayer of the surfactant is squeezed into three-dimensional (3D) stacks, acting as a surfactant reservoir. Moreover, studies have demonstrated the influence of hydrophobic nanoparticles on lung surfactant model systems, well before the outbreak of the COVID-19 pandemic. The potentially devastating effect of SARS-CoV-2 infection on vital lung function, including pneumonia and Acute respiratory distress syndrome (ARDS), meanwhile has been confirmed worldwide by thousands of fatal cases, although the mechanism of its onset is not completely understood. In theory, any virus carrying palmitoylated spike proteins (like beta-coronaviruses in general) might interfere with the alveolar surface activity, when infecting the deep respiratory system. However, it is clearly established that SARS-CoV-2 uses the Angiotensin converting enzyme 2 receptor (ACE2) for entry in the host, which receptor is expressed on the same type II pneumocytes, and, as a result, the virus may directly interfere with the secretion of surfactant proteins. This study aims at elucidating the main targets for containment of the spread of the SARS-CoV-2 virus via the respiratory system, a better understanding of the role of virus-surfactant interactions, the formation of aerosols and role of the inflammatory components of the immune system, as well as the role of positive pressure ventilation systems on particle exhalation, as being used at ICUs. Finally, suggestions are made for important goals for future biophysics research in infectious disease prevention and containment.