Article
Engineering, Environmental
Yu Lu, Wei-Min Ye, Qiong Wang, Yuan-Hong Zhu, Yong-Gui Chen, Bao Chen
Summary: The study found that bentonite exhibits anisotropic swelling behavior during static compaction, with significantly higher swelling strain along the perpendicular direction compared to the parallel direction. Increasing initial dry density results in higher swelling time, strain, and rate, while increasing vertical pressure decreases these parameters. The anisotropy coefficient initially increases and then stabilizes, with final anisotropy coefficient being influenced by initial dry density and vertical pressure.
BULLETIN OF ENGINEERING GEOLOGY AND THE ENVIRONMENT
(2021)
Article
Acoustics
Qiang Zhong, Haibo Chen, Alain Le Bot
Summary: This study extends the radiative energy transfer method (RETM) to anisotropic plates loaded by transverse point force at high frequencies, predicting energy flow fields and distributions accurately. Energy variables are superposed by incoherent rays emitted by actual and fictitious sources. The ray paths in unbounded homogeneous anisotropic media are shown to be straight lines based on Fermat's principle.
JOURNAL OF SOUND AND VIBRATION
(2021)
Article
Chemistry, Physical
Mario Calderon-Cueva, Wanyue Peng, Samantha M. Clarke, Jingxuan Ding, Benjamin L. Brugman, Gill Levental, Ashiwini Balodhi, Megan Rylko, Olivier Delaire, James P. S. Walsh, Susannah M. Dorfman, Alexandra Zevalkink
Summary: Alloys between Mg3Sb2 and Mg3Bi2 exhibit different bond strengths under high pressure, and a reversible phase transition phenomenon in the high-pressure structure was discovered.
CHEMISTRY OF MATERIALS
(2021)
Article
Computer Science, Interdisciplinary Applications
Shi Chen, Qin Li, Xu Yang
Summary: This paper explores the varying-mass Schrodinger equation with small random heterogeneities and derives a radiative transfer equation as its asymptotic limit. By systematically applying the Wigner transform and expanding the Wigner equation to proper orders, it is shown that the solutions of both VMSE and its limiting radiative transfer equation agree well in the classical regime.
JOURNAL OF COMPUTATIONAL PHYSICS
(2021)
Article
Physics, Particles & Fields
Kali Charan, Om Prakash Yadav, B. C. Tewari
Summary: The study focuses on the shear-free gravitational collapse of a charged radiating star, attempting to reduce the non-linearity in the Einstein field equations. A new ansatz is proposed to address the high degree of non-linearity and numerical solutions are demonstrated. The research concludes that the charge can delay or prevent the collapse of a star, while satisfying all energy conditions.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Mathematics, Applied
Fioralba Cakoni, Michael S. Vogelius, Jingni Xiao
Summary: In this paper, we investigate the necessary conditions for an anisotropic inhomogeneous medium to exhibit non-scattering behavior at a single wave number and for a single incident field. These conditions are related to the regularity of the boundary of the inhomogeneity. We make assumptions about the smoothness of the coefficients characterizing the constitutive material properties of the medium and the non-degeneracy of the incident wave. Our analysis involves the use of the Hodograph transform and regularity results for nonlinear elliptic partial differential equations. Our approach requires that the boundary a-priori belongs to the class C-1,C-a for some 0 < a < 1.
ARCHIVE FOR RATIONAL MECHANICS AND ANALYSIS
(2023)
Article
Mathematics, Applied
Fioralba Cakoni, Michael S. Vogelius, Jingni Xiao
Summary: In this paper, the necessary conditions for an anisotropic inhomogeneous medium to be non-scattering at a single wave number and for a single incident field are examined. These conditions are expressed in terms of the regularity of the boundary of the inhomogeneity. The analysis utilizes the Hodograph transform as well as regularity results for nonlinear elliptic partial differential equations, assuming that the coefficients characterizing the constitutive material properties of the medium are sufficiently smooth and the incident wave is appropriately non-degenerate.
ARCHIVE FOR RATIONAL MECHANICS AND ANALYSIS
(2023)
Article
Geosciences, Multidisciplinary
Arqam Muqtadir, Saud Al-Dughaimi, Taqi Alzaki, Jack Dvorkin
Summary: This study compares the P-wave and S-wave velocities obtained under different hydrostatic loading conditions using ultrasonic pulse transmission experiments. The results show significant differences in velocities when a smaller hydrostatic stress is added to axial stress, but these differences become smaller as the hydrostatic stress increases. The findings suggest that laboratory hydrostatic experiments can be used for in-situ velocity estimates even under strong in-situ contrasts between the vertical and horizontal stresses.
FRONTIERS IN EARTH SCIENCE
(2022)
Article
Materials Science, Multidisciplinary
Suhail Khan, Furqan Habib, Hassan Shah, Ali H. Alkhaldi, Akram Ali
Summary: This paper investigates exact solutions of anisotropic gravitating source with the cosmological constant in (n + 2) dimensional spacetime, considering collapse and expansion scenarios. By analyzing the expansion scalar and the mass function, the conditions for trapped surfaces are determined. Plots of pressures, anisotropy parameter, and energy density for both collapse and expansion scenarios are presented.
RESULTS IN PHYSICS
(2021)
Article
Materials Science, Multidisciplinary
Ming Dai
Summary: This paper investigates the existence and uniqueness of neutral inhomogeneities in isotropic and anisotropic planes under uniform external loadings on the matrix. The findings suggest that elliptical neutral inhomogeneities are necessary and unique in an anisotropic plane, even when interface parameters vary, while circular inhomogeneities are essential for neutrality in a plane with constant interface parameters across the entire interface.
MECHANICS OF MATERIALS
(2022)
Article
Computer Science, Interdisciplinary Applications
Eleni Gerolymatou, Julia Leuthold
Summary: This study investigates the oedometric compaction of materials with collapsible structure from a numerical point of view and finds that the reduction in permeability following the formation of compaction bands can be highly anisotropic. By using the finite element method and implementing a nonlocal formulation, the numerical stability issue caused by the localization of deformation is resolved.
COMPUTERS AND GEOTECHNICS
(2021)
Article
Multidisciplinary Sciences
C. F. Lo
Summary: The study shows that in the anisotropic two-photon Rabi model, the interaction between light and matter, as well as spin flipping, have competing impacts on the radiation mode, potentially leading to spectral collapse. When the coupling strength of the light-matter interaction exceeds a critical value, it dominates the frequency modulation.
SCIENTIFIC REPORTS
(2021)
Article
Multidisciplinary Sciences
Ignacio Martin-Navarro, Annalisa Pillepich, Dylan Nelson, Vicente Rodriguez-Gomez, Martina Donnari, Lars Hernquist, Volker Springel
Summary: An analysis of archival data from the Sloan Digital Sky Survey reveals that star-forming satellite galaxies are more common along the minor axis of central galaxies due to black hole feedback. However, quenched satellite galaxies are less frequent along the minor axis of their central galaxies, which is caused by an anisotropic signal resulting from the ejective nature of black hole feedback in massive halos.
Article
Mechanics
J. Chroscielewski, A. Sabik, B. Sobczyk, W. Witkowski
Summary: The paper discusses how to consider the asymmetry caused by drilling rotation when analyzing the failure of composite shells using the nonlinear 6-parameter shell theory. The results show that different failure criteria may result in slightly different damage zones and values of the first ply failure and ultimate load.
COMPOSITE STRUCTURES
(2021)
Article
Engineering, Mechanical
Xiaolei Chen, Thiebaud Richeton, Christian Motz, Stephane Berbenni
Summary: The study showed that surface conditions and grain boundaries have significant effects on dislocation image stress and dislocation distributions in a double-ended discrete dislocation pile-up, especially in the presence of a stiff layer which demonstrates a size effect on the dislocation image stress.
INTERNATIONAL JOURNAL OF PLASTICITY
(2021)
Article
Physics, Multidisciplinary
Anand Kaisavelu, S. Thirukkanesh, Megan Govender, S. D. Maharaj
Article
Physics, Particles & Fields
S. Thirukkanesh, Robert S. Bogadi, Megandhren Govender, Sibusiso Moyo
Summary: It has been found that models using the Vaidya-Tikekar metric potential together with the quadratic equation of state are favorable, and compared to other equations of state, the quadratic equation mimics the color-flavor-locked equation of state more closely.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
Sudan Hansraj, Megandhren Govender, Ayan Banerjee, Njabulo Mkhize
Summary: The standard Schwarzschild interior metric is conformally flat in Einstein and EGB gravity, generating a constant density sphere in any spacetime dimension. However, in EGB gravity, the conformal flatness criterion does not always yield the Schwarzschild metric, and the assumption of constant density does not always generate the Schwarzschild interior spacetime.
CLASSICAL AND QUANTUM GRAVITY
(2021)
Article
Physics, Multidisciplinary
Kevin P. Reddy, Megan Govender, Wesley Govender, Sunil D. Maharaj
Summary: In this work, the time-dependent Karmarkar condition is used to model dissipative gravitational collapse with shear, leading to a final static configuration. The collapse evolves into a static compact core with the exterior spacetime described by the vacuum Schwarzschild solution as the heat flux tends to zero. Hansraj and Moodly have shown that the final static configuration satisfies all physical requirements for a static compact object.
Article
Physics, Multidisciplinary
Satyanarayana Gedela, Neeraj Pant, Megandhren Govender
Summary: In this paper, a new exact anisotropic charged version of Pant's interior solution is presented, integrating coupled Einstein-Maxwell field equations to generate a family of new charged anisotropic solutions. Rigorous tests were conducted to validate the physical viability of the model, showing the intrinsic connection between the deformation parameter and key features.
BRAZILIAN JOURNAL OF PHYSICS
(2021)
Article
Physics, Particles & Fields
S. K. Maurya, Ksh. Newton Singh, M. Govender, Abdelghani Errehymy, Francisco Tello-Ortiz
Summary: In this article, the solution of the Einstein-Maxwell field equations in Brans-Dicke (BD) gravity with the presence of a massive scalar field describing a charged anisotropic strange star model is obtained using the embedding approach. The resulting model is rigorously tested for stability, causality, and regularity, and is able to accurately describe compact objects such as PSR J1903+327; Cen X-3; EXO 1785-248 and LMC X-4. The investigation reveals that the scalar field leads to higher surface charge densities, influencing the compactness of charged stars and altering physical characteristics of objects when the electric and scalar fields are coupled.
EUROPEAN PHYSICAL JOURNAL C
(2021)
Article
Astronomy & Astrophysics
S. K. Maurya, Ksh Newton Singh, M. Govender, Sudan Hansraj
Summary: The recent advance in the minimal geometric deformation (MGD) method has sparked interest in investigating higher-curvature gravitational effects in relativistic astrophysics. This study models a strange star using the MGD technique within the framework of Einstein-Gauss-Bonnet gravity. The findings demonstrate the existence of stable compact objects with masses exceeding the mass of a black hole without the need for exotic matter.
ASTROPHYSICAL JOURNAL
(2022)
Article
Physics, Multidisciplinary
Ksh Newton Singh, Megandhren Govender, Sudan Hansraj, Farook Rahaman
Summary: An exact anisotropic star model is constructed within the framework of pure Lovelock gravity, with a linear barotropic equation of state and a Finch-Skea potential. A comparison with the corresponding Einstein model reveals that the higher curvature effects induced by the Lovelock contributions result in lower densities, pressures, surface tensions, and anisotropy factors. The model also satisfies various stability tests.
ANNALEN DER PHYSIK
(2022)
Article
Physics, Multidisciplinary
Wesley Govender, Robert S. Bogadi, Megandhren Govender, Kevin J. Duffy
Summary: In this study, we investigate the impact of the equation of state (EoS) parameter on the collapse of a star undergoing dissipative collapse. Our results show that the EoS parameter significantly affects the various forces involved in gravitational collapse and influences the outcome of the collapse. We also find that the stiffness of the fluid is compromised in the presence of pressure anisotropy and heat flow.
Article
Mathematics, Applied
Genly Leon, Megandhren Govender, Andronikos Paliathanasis
Summary: In this study, we investigate the temporal equation of radiating stars using three powerful methods for the analysis of nonlinear differential equations. The global dynamics of the given master ordinary differential equation are explored to understand the evolution of solutions under different initial conditions and to examine the existence of asymptotic solutions. Additionally, Lie's theory is applied to reduce the order of the master differential equation and determine an exact similarity solution. It is found that the master equation possesses the Painleve property, allowing for expressions of the analytic solution in terms of a Laurent expansion.
MATHEMATICAL METHODS IN THE APPLIED SCIENCES
(2022)
Article
Astronomy & Astrophysics
S. K. Maurya, Ksh Newton Singh, M. Govender, Saibal Ray
Summary: In this work, we model compact objects within the framework of Einstein-Gauss-Bonnet (EGB) gravity using gravitational wave events GW 170817 and GW 190814, as well as observations of neutron stars PSR J1614-2230, PSR J1903 + 6620, and LMC X-4. We also explore the impact of anisotropy by varying the decoupling parameter using the extended gravitational decoupling (EGD) method. Our models, which include strange quark stars with the MIT Bag equation of state, are able to achieve the observed masses and radii of compact objects by adjusting the EGB parameter or the decoupling constant.
MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
(2023)
Article
Astronomy & Astrophysics
Bikram Keshari Parida, Shyam Das, Megandhren Govender
Summary: In this paper, the influence of tidal Love numbers on the equation-of-state governing the interior matter distribution of a compact star within the framework of classical general relativity is investigated. The Einstein field equations are solved for an arbitrary equation-of-state parameter by assuming a linear equation-of-state for a spherically symmetric anisotropic matter configuration. The model is subjected to rigorous regularity, causality, and stability tests, and shows a very good approximation of the pulsar 4U 1608-52. The intrinsic connection between the equation-of-state parameter and the tidal Love numbers is further demonstrated.
INTERNATIONAL JOURNAL OF MODERN PHYSICS D
(2023)
Article
Astronomy & Astrophysics
Sunil Kumar Maurya, Ksh. Newton Singh, Megandhren Govender, Ghulam Mustafa, Saibal Ray
Summary: Inspired by the gravitational event GW190814, this study models compact objects within the framework of f(Q) gravity using the method of gravitational decoupling. The findings reveal that the quadratic equation of state (EOS) is the most suitable and versatile model, capable of describing various compact objects, including neutron stars and the secondary component of GW190814.
ASTROPHYSICAL JOURNAL SUPPLEMENT SERIES
(2023)
Article
Physics, Particles & Fields
S. K. Maurya, M. Govender, G. Mustafa, Riju Nag
Summary: In this work, the Karmarkar condition and the concept of vanishing complexity are employed to generate models of compact stars within the framework of complete geometric deformation. Anisotropic pressure plays a key role in determining the stability of compact objects, while the magnitude of the decoupling constant determines the direction of energy flow.
EUROPEAN PHYSICAL JOURNAL C
(2022)
Article
Astronomy & Astrophysics
Sudan Hansraj, Megandhren Govender, Lushen Moodly, Ksh Newton Singh
Summary: We study the influence of higher curvature effects on stellar structure and find that the properties of stars are greatly affected when these terms are dynamic. By constructing a model of a superdense star with a strange star equation of state, we discover that the higher curvature terms reduce the speed of sound and significantly decrease the values of the surface gravitational redshift compared to general relativity. These findings have important implications for interpreting observations in relativistic astrophysics.