scholarly journals Method of integral equations in the polytropic theory of stars with axial rotation. I. Polytropes n=0 and n=1

2021 ◽  
Vol 8 (2) ◽  
pp. 338-358
Author(s):  
M. V. Vavrukh ◽  
◽  
D. V. Dzikovskyi ◽  
Keyword(s):  
Angular Velocity ◽  
Axial Rotation ◽  
Surface Shape ◽  
Equilibrium Equations ◽  
Polytropic Model ◽  
New Approach ◽  
Method Of Integral Equations ◽  
Integral Forms ◽  
Self Consistent ◽  
First Time

Calculations of characteristics of stars with axial rotation in the frame of polytropic model are based on the solution of mechanical equilibrium equation – differential equation of second order in partial derivatives. Different variants of approximate determinations of integration constants are based on traditional in the theory of stellar surface approximation, namely continuity of gravitational potential in the surface vicinity. We proposed a new approach, in which we used simultaneously differential and integral forms of equilibrium equations. This is a closed system and allows us to define in self-consistent way integration constants, the polytrope surface shape and distribution of matter over volume of a star. With the examples of polytropes n=0 and n=1, we established the existence of two rotation modes (with small and large eccentricities). It is proved that the polytrope surface is the surface of homogeneous rotational ellipsoid for the case n=0. The polytrope characteristics with n=1 in different approximations were calculated as the functions of angular velocity. For the first time it has been calculated the deviation of polytrope surface at fixed value of angular velocity from the surface of associated rotational ellipsoid.

Method of integral equations in the polytropic theory of stars with axial rotation. II. Polytropes with indices $n>1$

2021 ◽  
Vol 8 (3) ◽  
pp. 474-485
Author(s):  
M. V. Vavrukh ◽  
◽  
D. V. Dzikovskyi ◽  
Keyword(s):  
Integral Form ◽  
Axial Rotation ◽  
Geometrical Parameters ◽  
Surface Form ◽  
Equilibrium Equations ◽  
Method Of Integral Equations ◽  
Mass Moment ◽  
Self Consistent ◽  
Nonlinear Equilibrium ◽  
Mass Moment Of Inertia

A new method for finding solutions of the nonlinear equilibrium equations for rotational polytropes was proposed, which is based on a self-consistent description of internal region and periphery using the integral form of equations. Dependencies of geometrical parameters, surface form, mass, moment of inertia and integration constants on angular velocity were calculated for indices $n=2.5$ and $n=3$.

A multi-manned assembly line balancing problem with classified teams: a new approach

2016 ◽  
Vol 36 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Hamid Yilmaz ◽  
Mustafa Yilmaz
Keyword(s):  
Design Methodology ◽  
Assembly Line ◽  
Assembly Line Balancing ◽  
Line Balancing ◽  
Test Problems ◽  
New Approach ◽  
Content Type ◽  
Line Test ◽  
Assembly Line Balancing Problem ◽  
First Time

Purpose – Within team-oriented approaches, tasks are assigned to teams before being assigned to workstations as a reality of industry. So it becomes clear, which workers assemble which tasks. Design/methodology/approach – Team numbers of the assembly line can increase with the number of tasks, but at the same time, due to physical situations of the stations, there will be limitations of maximum working team numbers in a station. For this purpose, heuristic assembly line balancing (ALB) procedure is used and mathematical model is developed for the problem. Findings – Well-known assembly line test problems widely used in the literature are solved to indicate the effectiveness and applicability of the proposed approach in practice. Originality/value – This paper draws attention to ALB problem in which workers have been assigned to teams in advance due to the need for specialized skills or equipment on the line for the first time.

A New Approach for the Fabrication of Tetragonal BaTiO3 Nanoparticles

2021 ◽  
Vol 21 (4) ◽  
pp. 2692-2701
Author(s):  
Vu T. Tan ◽  
La The Vinh ◽  
Vu Minh Khoi ◽  
Huynh Dang Chinh ◽  
Pham Van Tuan ◽  
...  
Keyword(s):  
Ferroelectric Properties ◽  
Particle Size Effect ◽  
Ferroelectric Material ◽  
Tem Analysis ◽  
New Approach ◽  
Xrd Pattern ◽  
Munk Function ◽  
Oxide Nanoparticle ◽  
First Time ◽  
Batio3 Nanoparticles

For the first time, the BaTiO3 nano-sized particles were obtained through solid-state reaction by employing the titanium oxide nanoparticle. Meanwhile, by using TiO2 with micro-sized particles, the synthesized BaTiO3 shows the micro-sized. The XRD pattern confirms that both BaTiO3 nano-sized and micro-sized particles display the tetragonal structure. Both SEM and TEM analysis revealed that the size of the nano-sized material is in the range of 30–50 nm; in the meantime, the microsized material shows a size of 500 nm. The Eg of both BaTiO3 micro-sized and nano-sized were calculated by using the Kubelka-Munk function. The shifted bandgap of BaTiO3 nano-sized particle is nearly 0.24 eV larger than that of BaTiO3 miro-sized particle due to the particle size effect. The P-E measurement of n-BaTiO3 proved that the obtained BaTiO3 nano-sized is ferroelectric material. The result may provide a new route for the fabrication of barium titanate nanoparticle with ferroelectric properties.

scholarly journals Exploiting superspace to clarify vacancy and Al/Si ordering in mullite

IUCrJ ◽  
2018 ◽  
Vol 5 (4) ◽  
pp. 497-509 ◽  
Author(s):  
Paul Benjamin Klar ◽  
Iñigo Etxebarria ◽  
Gotzon Madariaga
Keyword(s):  
Density Functional ◽  
X Ray Diffraction ◽  
Intrinsic Structure ◽  
Functional Theory ◽  
New Approach ◽  
X Ray ◽  
Vacancy Ordering ◽  
Harmonic Modulation ◽  
First Time

Synchrotron single-crystal X-ray diffraction has revealed diffuse scattering alongside sharp satellite reflections for different samples of mullite (Al4+2xSi2−2xO10−x). Structural models have been developed in (3+1)-dimensional superspace that account for vacancy ordering and Al/Si ordering based on harmonic modulation functions. A constraint scheme is presented which explains the crystal-chemical relationships between the split sites of the average structure. The modulation amplitudes of the refinements differ significantly by a factor of ∼3, which is explained in terms of different degrees of ordering,i.e.vacancies follow the same ordering principle in all samples but to different extents. A new approach is applied for the first time to determine Al/Si ordering by combining density functional theory with the modulated volumes of the tetrahedra. The presence of Si–Si diclusters indicates that the mineral classification of mullite needs to be reviewed. A description of the crystal structure of mullite must consider both the chemical composition and the degree of ordering. This is of particular importance for applications such as advanced ceramics, because the physical properties depend on the intrinsic structure of mullite.

scholarly journals Elephant Herding Optimization for Energy-Based Localization

2018 ◽  
Author(s):  
Sérgio Correia ◽  
Marko Beko ◽  
Luís Cruz ◽  
Slavisa Tomic
Keyword(s):  
Source Localization ◽  
Wireless Sensors ◽  
Performance Comparison ◽  
Sensor Nodes ◽  
Convex Relaxations ◽  
Noisy Environments ◽  
New Approach ◽  
Metaheuristic Methods ◽  
Simulation Results ◽  
First Time

This work addresses the energy-based source localization problem in wireless sensors networks. Instead of circumventing the maximum likelihood (ML) problem by applying convex relaxations and approximations (like all existing approaches do), we here tackle it directly by the use of metaheuristics. To the best of our knowledge, this is the first time that metaheuristics is applied to this type of problems. More specifically an elephant herding optimization (EHO) algorithm is applied. Through extensive simulations, the key parameters of the EHO algorithm are optimized such that they match the energy decay model between two sensor nodes. A detailed analysis of the computational complexity is presented, as well as performance comparison between the proposed algorithm and existing non-metaheuristic ones. Simulation results show that the new approach significantly outperforms the existing solutions in noisy environments, encouraging further improvement and testing of metaheuristic methods.

scholarly journals Quantification of Sub-Solar Star Ages from the Symmetry of Conjugate Histograms of Spin Period and Angular Velocity

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1519
Author(s):  
Robert E. Criss ◽  
Anne M. Hofmeister
Keyword(s):  
Angular Velocity ◽  
Rotation Period ◽  
Axial Rotation ◽  
Open Clusters ◽  
Interstellar Gas ◽  
Spin Period ◽  
Inverse Models ◽  
Star Production ◽  
Star Ages ◽  
Large Clusters

Empirical laws proposed for the decline in star spin with time have heretofore been tested using ambiguous fitting models. We develop an analytical inverse model that uses histogram data to unequivocally determine the physical law governing how dwarf star spin depends on time (t) and mass (M). We analyze shapes of paired histograms of axial rotation period (П) and angular velocity (ω = 2π/П) to utilize the fact that a variable and its reciprocal are governed by the same physics. Copious data on open clusters are used to test the formula ∂ω/∂t ∝ − ωn where n is unrestricted, and thus covers diverse possibilities. Histogram conjugates for each of 15 clusters with 120 to 812 measurements provide n = 1.13 ± 0.19. Results are independent of initial spin rate, bin size, cluster parameters, and star mass. Notably, 11 large clusters with mostly M-types yield fits with n = 1.07 ± 0.12. Associations behave similarly. Only exponential decay (n = 1) explains the similar shapes of the conjugate histograms for the spin period and angular velocity, despite the asymmetric (inverse) relationship of these variables. This rate law is consistent with viscous dissipation. Forward modeling confirms that n is near unity and further shows that coeval formation of all stars in a cluster does not occur. We therefore explore a constant rate of star production, which is reasonable for tiny stars. Inverse models show that episodic production increases with mass, but is unimportant below ~0.55 MSun. We infer star and cluster ages, and find that star production becomes less regular with time, as interstellar gas and dust are progressively depleted. Our new analytical approach of extracting a physical law from conjugate histograms is general and widely applicable.

Imperial Impotence: Treason in 1774 Massachusetts

2011 ◽  
Vol 29 (3) ◽  
pp. 657-701
Author(s):  
Neil L. York
Keyword(s):  
Edmund Burke ◽  
Henry Viii ◽  
House Of Commons ◽  
New Approach ◽  
The Subject ◽  
American Policy ◽  
First Time ◽  
The Way

So contended Edmund Burke in the House of Commons, during a May 1770 speech that ridiculed the government's American policy. It was not the first time Burke raised the subject of this 1543 statute. He had asked—rhetorically—during debates two weeks before, “The Act of Henry VIII. Did you mean to execute that?” He then answered his own question, the scorn beneath it probably apparent to all. “You showed your ill will to America, at the same time you dared not execute it.” Burke hoped that by shaming the ministry he might be able to push through a set of resolutions condemning its policies, which could open the way for a new approach to imperial management. He failed, but that did not mean he had been wrong about the futility of threatening to resurrect an old statute to intimidate protesting Americans.

scholarly journals Theoretical Design and Circuit Implementation of Integer Domain Chaotic Systems

2014 ◽  
Vol 24 (10) ◽  
pp. 1450128 ◽  
Author(s):  
Qianxue Wang ◽  
Simin Yu ◽  
Christophe Guyeux ◽  
Jacques M. Bahi ◽  
Xiaole Fang
Keyword(s):  
Chaotic Systems ◽  
Chaotic Behavior ◽  
Random Sequence ◽  
Noise Signal ◽  
Circuit Implementation ◽  
New Approach ◽  
Uniform Noise ◽  
Definition Of ◽  
First Time ◽  
Hybrid Circuit

In this paper, a new approach for constructing integer domain chaotic systems (IDCS) is proposed, and its chaotic behavior is mathematically proven according to Devaney's definition of chaos. Furthermore, an analog-digital hybrid circuit is also developed for realizing the designed basic IDCS. In the IDCS circuit design, chaos generation strategy is realized through a sample-hold circuit and a decoder circuit so as to convert the uniform noise signal into a random sequence, which plays a key role in circuit implementation. The experimental observations further validate the proposed systematic methodology for the first time.

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