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Assessment of Near-Earth Asteroid Deflection Techniques via Spherical Fuzzy Sets 球面模糊集评价近地小行星偏转技术
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-03-08 DOI: 10.1155/2021/6678056
M. Fernández-Martínez, J. Sánchez-Lozano
{"title":"Assessment of Near-Earth Asteroid Deflection Techniques via Spherical Fuzzy Sets","authors":"M. Fernández-Martínez, J. Sánchez-Lozano","doi":"10.1155/2021/6678056","DOIUrl":"https://doi.org/10.1155/2021/6678056","url":null,"abstract":"Extensions of fuzzy sets to broader contexts constitute one of the leading areas of research in the context of problems in artificial intelligence. Their aim is to address decision-making problems in the real world whenever obtaining accurate and sufficient data is not a straightforward task. In this way, spherical fuzzy sets were recently introduced as a step beyond to modelize such problems more precisely on the basis of the human nature, thus expanding the space of membership levels, which are defined under imprecise circumstances. The main goal in this study is to apply the spherical fuzzy set version of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS), a well-established multicriteria decision-making approach, in the context of planetary defense. As of the extraction of knowledge from a group of experts in the field of near-Earth asteroids, they rated four deflection technologies of asteroids (kinetic impactor, ion beam deflection, enhanced gravity tractor, and laser ablation) that had been previously assessed by means of the classical theory of fuzzy series. This way, a comparative study was carried out whose most significant results are the kinetic impactor being the most suitable alternative and the spherical fuzzy set version of the TOPSIS approach behaves more sensitively than the TOPSIS procedure for triangular fuzzy sets with regard to the information provided by our group of experts.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":"16 1","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"64763646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 9
Bouncing Cosmology in f G , T Gravity with Logarithmic Trace Term 具有对数迹项的fG，T引力中的反弹宇宙学
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-03-02 DOI: 10.1155/2021/8852581
M. Shamir
{"title":"Bouncing Cosmology in \u0000 f\u0000 \u0000 \u0000 G\u0000 ,\u0000 T\u0000 \u0000 \u0000 Gravity with Logarithmic Trace Term","authors":"M. Shamir","doi":"10.1155/2021/8852581","DOIUrl":"https://doi.org/10.1155/2021/8852581","url":null,"abstract":"This study is devoted to explore bouncing cosmology in the context of \u0000 \u0000 f\u0000 \u0000 \u0000 G\u0000 ,\u0000 T\u0000 \u0000 \u0000 \u0000 theory of gravity. For this purpose, a Gauss–Bonnet cosmological model with logarithmic trace term is considered. In particular, the possibility of obtaining bouncing solutions by considering two equations of state parameters is investigated. A graphical analysis is provided for analyzing the obtained bouncing solutions. The energy conditions are discussed in detail. It is interesting to notice that null and strong energy conditions are violated near the neighborhood of bouncing points justifying the accelerating universe in the light of the recent observational data. The behavior of the scale factor, red shift function, deceleration parameter, and Hubble parameter is also debated. An important feature of the current study is the discussion of conservation equation in \u0000 \u0000 f\u0000 \u0000 \u0000 G\u0000 ,\u0000 T\u0000 \u0000 \u0000 \u0000 gravity. The possibility of some suitable constraint equations which recover the standard conservation equation is discussed, and all the free parameters are assumed accordingly. All the results in this study suggest that the proposed \u0000 \u0000 f\u0000 \u0000 \u0000 G\u0000 ,\u0000 T\u0000 \u0000 \u0000 \u0000 gravity model provides good bouncing solutions with the chosen EoS parameters.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-03-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45102048","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Fault Tolerance for Active Surface System with Actuator Faults 具有执行器故障的有源表面系统的容错
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-02-26 DOI: 10.1155/2021/6675846
Danqing Zhang, B. Xiang, A. Yusup, Na Wang, Guljaina Kazezkhan
{"title":"Fault Tolerance for Active Surface System with Actuator Faults","authors":"Danqing Zhang, B. Xiang, A. Yusup, Na Wang, Guljaina Kazezkhan","doi":"10.1155/2021/6675846","DOIUrl":"https://doi.org/10.1155/2021/6675846","url":null,"abstract":"The QiTai Radio Telescope (QTT) will be equipped with the active surface adjustment system (ASAS) to correct the main reflector deformation caused by environmental loading. In order to guarantee the stability and performance of the active surface system under fault conditions, it is necessary to adopt the fault-tolerant method when actuator faults have occurred. In this paper, a fault control method based on actuator faults weighting is proposed to solve the active surface fault control problem. According to the coordinates of the adjustable points of the panels corresponding to the faulty actuators, a new paraboloid is fitted by a weighted health matrix, and the fitting surface is taken as the target to adjust the surface shape.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":"2021 1","pages":"1-12"},"PeriodicalIF":1.4,"publicationDate":"2021-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44693147","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The Stability of Certain Motion of a Charged Gyrostat in Newtonian Force Field 带电陀螺在牛顿力场中某些运动的稳定性
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-02-22 DOI: 10.1155/2021/6660028
A. Elmandouh, Fatimah H. Alsaad
{"title":"The Stability of Certain Motion of a Charged Gyrostat in Newtonian Force Field","authors":"A. Elmandouh, Fatimah H. Alsaad","doi":"10.1155/2021/6660028","DOIUrl":"https://doi.org/10.1155/2021/6660028","url":null,"abstract":"This work aims to study the stability of certain motions of a rigid body rotating about its fixed point and carrying a rotor that rotates with constant angular velocity about an axis parallel to one of the principal axes. This motion is presumed to take place due to the combined influence of the magnetic field and the Newtonian force field. The equations of motion are deduced, and moreover, they are expressed as a Lie–Poisson Hamilton system. The permanent rotations are calculated and interpreted mechanically. The sufficient conditions for instability are presented employing the linear approximation method. The energy-Casimir method is applied to gain sufficient conditions for stability. The regions of linear stability and Lyapunov stability are illustrated graphically for certain values of the parameters.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":"2021 1","pages":"1-11"},"PeriodicalIF":1.4,"publicationDate":"2021-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46044152","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Impacts of Poynting–Robertson Drag and Dynamical Flattening Parameters on Motion around the Triangular Equilibrium Points of the Photogravitational ER3BP Poyinting–Robertson阻力和动力学展平参数对光引力ER3BP三角平衡点周围运动的影响
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-02-11 DOI: 10.1155/2021/6657500
A. Umar, Aminu Abubakar Hussain
{"title":"Impacts of Poynting–Robertson Drag and Dynamical Flattening Parameters on Motion around the Triangular Equilibrium Points of the Photogravitational ER3BP","authors":"A. Umar, Aminu Abubakar Hussain","doi":"10.1155/2021/6657500","DOIUrl":"https://doi.org/10.1155/2021/6657500","url":null,"abstract":"Using an analytical and numerical study, this paper investigates the equilibrium state of the triangular equilibrium points \u0000 \u0000 \u0000 \u0000 L\u0000 \u0000 \u0000 4\u0000 ,\u0000  \u0000  \u0000 5\u0000 \u0000 \u0000 \u0000 of the Sun-Earth system in the frame of the elliptic restricted problem of three bodies subject to the radial component of Poynting–Robertson (P–R) drag and radiation pressure factor of the bigger primary as well as dynamical flattening parameters of both primary bodies (i.e., Sun and Earth). The equations of motion are presented in a dimensionless-pulsating coordinate system \u0000 \u0000 \u0000 \u0000 ξ\u0000 −\u0000 η\u0000 \u0000 \u0000 \u0000 , and the positions of the triangular equilibrium points are found to depend on the mass ratio \u0000 \u0000 \u0000 \u0000 μ\u0000 \u0000 \u0000 \u0000 and the perturbing forces involved in the equations of motion. A numerical analysis of the positions and stability of the triangular equilibrium points of the Sun-Earth system shows that the perturbing forces have no significant effect on the positions of the triangular equilibrium points and their stability. Hence, this research work concludes that the motion of an infinitesimal mass near the triangular equilibrium points of the Sun-Earth system remains linearly stable in the presence of the perturbing forces.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":"62 2","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41296803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Chaotic Oscillation of Satellite due to Aerodynamic Torque 气动力矩引起的卫星混沌振荡
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-02-10 DOI: 10.1155/2021/6658051
R. Bhardwaj, Mohammad Sajid
{"title":"Chaotic Oscillation of Satellite due to Aerodynamic Torque","authors":"R. Bhardwaj, Mohammad Sajid","doi":"10.1155/2021/6658051","DOIUrl":"https://doi.org/10.1155/2021/6658051","url":null,"abstract":"This study presents the chaotic oscillation of the satellite around the Earth due to aerodynamic torque. The orbital plane of the satellite concurs is same as the tropical plane of Earth. The half-width of riotous separatrix is assessed utilizing Chirikov’s measure. Variety of boundary techniques shows that streamlined force boundary (ɛ), unpredictability of circle (e), and mass-proportion (ω0) convert normal wavering to the disorganized one. We studied the behavior of trajectories due to change in parameters with Lyapunov exponents and time series plots. The theory is applied to Resourcesat-1, an artificial satellite of the Earth.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45648296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
A Generic Embedding Class-I Model via Karmarkar Condition in f ℛ , T Gravity 重力条件下基于Karmarkar条件的一类嵌入模型
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-02-08 DOI: 10.1155/2021/6685578
M. Zubair, S. Waheed, H. Javaid
{"title":"A Generic Embedding Class-I Model via Karmarkar Condition in \u0000 f\u0000 \u0000 \u0000 ℛ\u0000 ,\u0000 T\u0000 \u0000 \u0000 Gravity","authors":"M. Zubair, S. Waheed, H. Javaid","doi":"10.1155/2021/6685578","DOIUrl":"https://doi.org/10.1155/2021/6685578","url":null,"abstract":"In the present work, we investigate the existence of compact star model in the background of f(R, T) gravity theory, where R represents the Ricci scalar and T refers to the energy-momentum tensor trace. Here, we use Karmarkar condition for the interior stellar setup so that a complete and precise model following the embedding class-I strategy can be obtained. For this purpose, we assume anisotropic matter contents along with static and spherically symmetric geometry of compact star. As Karmarkar embedding condition yields a relationship of metric potentials, therefore we assume a suitable form for one of the metric components as eφ � ar2 + b 1rn + 1, where a and b represent constants and n is a free parameter, and evaluate the other. We approximate the values of physical parameters like a, A, and B by utilizing the known values of mass and radius for the compact star Vela X-1. +e validity of the acquired model is then explored for different values of coupling parameter λ graphically. It is found that the resulting solution is physically interesting and well-behaved.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":"1-16"},"PeriodicalIF":1.4,"publicationDate":"2021-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45607788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 4
Scaling Laws in the Stellar Mass Distribution and the Transition to Homogeneity 恒星质量分布的标度律及其向均匀性的转变
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-02-05 DOI: 10.1155/2021/6680938
Jose Gaite
{"title":"Scaling Laws in the Stellar Mass Distribution and the Transition to Homogeneity","authors":"Jose Gaite","doi":"10.1155/2021/6680938","DOIUrl":"https://doi.org/10.1155/2021/6680938","url":null,"abstract":"We present a new statistical analysis of the large-scale stellar mass distribution in the Sloan Digital Sky Survey (data release 7). A set of volume-limited samples shows that the stellar mass of galaxies is concentrated in a range of galaxy luminosities that is very different from the range selected by the usual analysis of galaxy positions. Nevertheless, the two-point correlation function is a power-law with the usual exponent $gamma=1.71$--$1.82$, which varies with luminosity. The mass concentration property allows us to make a meaningful analysis of the angular distribution of the full flux-limited sample. With this analysis, after suppressing the shot noise, we extend further the scaling range and thus obtain $gamma=1.83$ and a clustering length redc{$r_0= 5.8$--$7.0,h^{-1}$Mpc.} Fractional statistical moments of the coarse-grained stellar mass density exhibit multifractal scaling. Our results support a multifractal model with a transition to homogeneity at about $10,h^{-1}$Mpc.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":"2021 1","pages":"1-13"},"PeriodicalIF":1.4,"publicationDate":"2021-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42711980","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Magnetohydrodynamic Fluid Flow due to an Unsteady Stretching Sheet with Thermal Radiation, Porous Medium, and Variable Heat Flux 具有热辐射、多孔介质和可变热通量的非稳态拉伸薄板引起的磁流体动力学流动
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-01-31 DOI: 10.1155/2021/6686883
A. Megahed, N. Ghoneim, M. G. Reddy, M. El-Khatib
{"title":"Magnetohydrodynamic Fluid Flow due to an Unsteady Stretching Sheet with Thermal Radiation, Porous Medium, and Variable Heat Flux","authors":"A. Megahed, N. Ghoneim, M. G. Reddy, M. El-Khatib","doi":"10.1155/2021/6686883","DOIUrl":"https://doi.org/10.1155/2021/6686883","url":null,"abstract":"A shooting method has been introduced for determining the numerical solution of the ordinary differential equations which describe the Newtonian magnetohydrodynamic laminar fluid flow due to an unsteady stretching sheet together with the presence of thermal radiation and variable heat flux. The variable viscosity and variable conductivity are taken into consideration. Absence of magnetic field in some studies restricts the development of the energy-efficient heat transfer mechanism as is desired in numerous applications. The present study encompasses parameters such as unsteadiness parameter, porous parameter, viscosity parameter, magnetic number, radiation parameter, and conductivity parameter. It has been consummated that the proposed model is superior to other existing models for the industrial fluid.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44530846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 9
Compact Stars Admitting Noether Symmetries in Energy-Momentum Squared Gravity 在能量动量平方引力中承认诺特对称的致密恒星
IF 1.4 4区 物理与天体物理
Advances in Astronomy Pub Date : 2021-01-26 DOI: 10.1155/2021/6663502
M. Sharif, M. Z. Gul
{"title":"Compact Stars Admitting Noether Symmetries in Energy-Momentum Squared Gravity","authors":"M. Sharif, M. Z. Gul","doi":"10.1155/2021/6663502","DOIUrl":"https://doi.org/10.1155/2021/6663502","url":null,"abstract":"This paper investigates the geometry of compact stellar objects through the Noether symmetry approach in the energy-momentum squared gravity. This newly developed theory overcomes the problems of big bang singularity and provides the viable cosmological consequences in the early time universe. Moreover, its implications occur in high curvature regime where the deviations of energy-momentum squared gravity from general relativity is confirmed. We consider the minimal coupling model of this modified theory and formulate symmetry generators as well as corresponding conserved quantities. We use conservation relation and apply some suitable initial conditions to evaluate the metric potentials. Finally, we explore some interesting features of the compact objects for appropriate values of the model parameters through numeric analysis. It is found that compact stellar objects in this particular framework depend on the model parameters as well as conserved quantities. We conclude that Noether symmetries generate solutions that are consistent with the astrophysical observational data and hence confirm the viability of this procedure.","PeriodicalId":48962,"journal":{"name":"Advances in Astronomy","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2021-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48961490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 13
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