This document discusses research on identifying the densest arrangements, or close packings, of identical hard spheres confined within cylinders of varying diameters. The researchers adapted an adaptive-shrinking-cell and sequential-linear-programming technique to find close packings up to a cylinder diameter of 4.00 times the sphere diameter. They identified 17 new close packing structures, most of which have chiral, or handed, geometries. Beyond a cylinder diameter of around 2.85 times the sphere diameter, most structures consist of an outer shell and inner core competing to be closely packed. In some cases, the shell or core adopts its own maximum density arrangement, and in other cases the packing involves an interplay between the shell and core.
This document presents a study on common fixed points of weakly compatible mappings under a new property in fuzzy metric spaces. It begins with introducing concepts such as fuzzy metric spaces, continuous t-norms, convergence of sequences, completeness, compatibility of mappings, and weakly compatible pairs. It then presents prior theorems on common fixed points proved by other authors. The main result proved is Theorem 1, which shows that two mappings have a unique common fixed point in a fuzzy metric space if they satisfy certain conditions, including the new (S-B) property and weak compatibility. This extends an earlier fixed point theorem to the setting of fuzzy metric spaces under the new property. Examples are provided to illustrate the concepts and properties discussed.
ON APPROACH TO INCREASE DENSITY OF FIELD- EFFECT TRANSISTORS IN AN INVERTER C...antjjournal
In this paper we consider an approach to decrease dimensions of field-effect transistors framework invertors with increasing of their density. Framework the approach it is necessary to manufacture a
heterostructure, which consist of two layers. One of them includes into itself several sections. After manufacturing of the heterostructure these sections should be doped by diffusion or by ion implantation with future optimized annealing of dopant and/or radiation defects. To prognosis the technological process we consider an analytical approach, which gives a possibility to take into account variation of physical parameters in space and time. At the same time the approach gives a possibility to take into
account nonlinearity of mass and heat transport and to analyze the above transport without crosslinking solutions on interfaces between materials of heterostructure.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Dynamic Relaxation (DR) method is presented for the analysis of geometrically linear laterally loaded, rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse shear deformations. A computer program has been compiled. The convergence and accuracy of the DR solutions of isotropic, orthotropic, and laminated plates for elastic small deflection response are established by comparison with different exact and approximate solutions. The present Dynamic Relaxation (DR) method shows a good agreement with other analytical and numerical methods used in the verification scheme. It was found that: The convergence and accuracy of the DR solution were dependent on several factors which include boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR small deflection program using uniform meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads in a fairly good accuracy.
A composite material can be defined as a combination of two or more materials that
gives better properties than those of the individual components used alone. In contrast to
metallic alloys, each material retains its separate chemical, physical, and mechanical
properties. The two constituents are reinforcement and a matrix. The main advantages of
composite materials are their high strength and stiffness combined with low density when
compared to classical materials. Micromechanical approach is found to be more suitable for
the analysis of composite materials because it studies the volume proportions of the
constituents for the desired lamina stiffness and strength.
This document discusses theories of composite plates and numerical methods used for bending and buckling analysis of laminated plates. It summarizes different plate theories including classical laminate theory (CLPT), first-order shear deformation theory (FSDT), and higher-order shear deformation theory (HSDT). Numerical methods covered include finite difference method (FDM), dynamic relaxation (DR), and finite element method (FEM). The document concludes that FEM can provide acceptable accuracy for modeling composite plates and is applicable to complex geometries.
1) A finite element method was used to simulate the indentation of a ductile substrate coated with a thin elastic film using a rigid spherical indenter.
2) During loading, delamination was found to initiate tangentially at a distance of two to three times the contact radius.
3) During unloading, a circular part of the coating directly under the contact area was lifted off from the substrate, indicating normal delamination. Normal delamination was seen as a hump on the load-displacement curve.
4) There was a critical interfacial strength above which delamination could be prevented for a given indentation depth and material system. The effects of residual stress in the film and interface waviness
This document presents a study analyzing the static flexural behavior of thick isotropic beams using a higher order shear deformation theory. The theory considers axial displacement as consisting of elementary bending theory displacement plus a hyperbolic shear deformation term. Governing differential equations are derived through the principle of virtual work. Numerical results for axial displacement, transverse displacement, stresses are obtained for cantilever beams under transverse loading and compared to other theories.
This document presents a study on common fixed points of weakly compatible mappings under a new property in fuzzy metric spaces. It begins with introducing concepts such as fuzzy metric spaces, continuous t-norms, convergence of sequences, completeness, compatibility of mappings, and weakly compatible pairs. It then presents prior theorems on common fixed points proved by other authors. The main result proved is Theorem 1, which shows that two mappings have a unique common fixed point in a fuzzy metric space if they satisfy certain conditions, including the new (S-B) property and weak compatibility. This extends an earlier fixed point theorem to the setting of fuzzy metric spaces under the new property. Examples are provided to illustrate the concepts and properties discussed.
ON APPROACH TO INCREASE DENSITY OF FIELD- EFFECT TRANSISTORS IN AN INVERTER C...antjjournal
In this paper we consider an approach to decrease dimensions of field-effect transistors framework invertors with increasing of their density. Framework the approach it is necessary to manufacture a
heterostructure, which consist of two layers. One of them includes into itself several sections. After manufacturing of the heterostructure these sections should be doped by diffusion or by ion implantation with future optimized annealing of dopant and/or radiation defects. To prognosis the technological process we consider an analytical approach, which gives a possibility to take into account variation of physical parameters in space and time. At the same time the approach gives a possibility to take into
account nonlinearity of mass and heat transport and to analyze the above transport without crosslinking solutions on interfaces between materials of heterostructure.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Dynamic Relaxation (DR) method is presented for the analysis of geometrically linear laterally loaded, rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse shear deformations. A computer program has been compiled. The convergence and accuracy of the DR solutions of isotropic, orthotropic, and laminated plates for elastic small deflection response are established by comparison with different exact and approximate solutions. The present Dynamic Relaxation (DR) method shows a good agreement with other analytical and numerical methods used in the verification scheme. It was found that: The convergence and accuracy of the DR solution were dependent on several factors which include boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR small deflection program using uniform meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads in a fairly good accuracy.
A composite material can be defined as a combination of two or more materials that
gives better properties than those of the individual components used alone. In contrast to
metallic alloys, each material retains its separate chemical, physical, and mechanical
properties. The two constituents are reinforcement and a matrix. The main advantages of
composite materials are their high strength and stiffness combined with low density when
compared to classical materials. Micromechanical approach is found to be more suitable for
the analysis of composite materials because it studies the volume proportions of the
constituents for the desired lamina stiffness and strength.
This document discusses theories of composite plates and numerical methods used for bending and buckling analysis of laminated plates. It summarizes different plate theories including classical laminate theory (CLPT), first-order shear deformation theory (FSDT), and higher-order shear deformation theory (HSDT). Numerical methods covered include finite difference method (FDM), dynamic relaxation (DR), and finite element method (FEM). The document concludes that FEM can provide acceptable accuracy for modeling composite plates and is applicable to complex geometries.
1) A finite element method was used to simulate the indentation of a ductile substrate coated with a thin elastic film using a rigid spherical indenter.
2) During loading, delamination was found to initiate tangentially at a distance of two to three times the contact radius.
3) During unloading, a circular part of the coating directly under the contact area was lifted off from the substrate, indicating normal delamination. Normal delamination was seen as a hump on the load-displacement curve.
4) There was a critical interfacial strength above which delamination could be prevented for a given indentation depth and material system. The effects of residual stress in the film and interface waviness
This document presents a study analyzing the static flexural behavior of thick isotropic beams using a higher order shear deformation theory. The theory considers axial displacement as consisting of elementary bending theory displacement plus a hyperbolic shear deformation term. Governing differential equations are derived through the principle of virtual work. Numerical results for axial displacement, transverse displacement, stresses are obtained for cantilever beams under transverse loading and compared to other theories.
A new method is developed for determining material hardness from depth sensing indentation tests. Both loading and unloading data are used to calculate Meyer hardness values, which agree well with conventional optical measurements. While the new method characterizes hardness even for elastic materials, the conventional mean contact pressure definition differs significantly from hardness for elastic materials. A relationship is found between work during loading and unloading that allows hardness to be calculated using only load-depth data.
Dependence of Charge Carriers Mobility in the P-N-Heterojunctions on Composit...msejjournal
In this paper we consider manufacturing a p-n-junctions by dopant diffusion or ion implantation into a multilayer structure. We introduce an approach to increase sharpness of these p-n-junctions and at the same time to increase homogeneity of distributions of dopants in enriched by these dopants areas. We consider influence of the above changing of distribution of dopant on charge carrier mobility. We also consider an approach to decrease value of mismatch-induced stress in the considered multilayer structure by using a buffer layer. The decreasing gives a possibility to increase value of charge carrier mobility.
Dynamic Relaxation (DR) method is presented for the geometrically nonlinear laterally loaded,
rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse
shear deformation. A computer program has been compiled. The convergence and accuracy of the DR
solutions for elastic large deflection response are established by comparison with various exact and
approximate solutions. New numerical results are generated for uniformly loaded square laminated
plates which serve to quantify the effects of shear deformation, length to thickness ratio, number of
layers, material anisotropy and fiber orientation.
It was found that linear analysis seriously over predicts deflection of plates. The shear
deflection depends greatly on a number of factors such as length to thickness ratio, degree of
anisotropy and number of layers. As the degree of anisotropy increases, the plate becomes stiffer and
when it is greater than a critical value, the deflection becomes virtually independent on the degree of
anisotropy. It was also found that deflection of plates depends on the angle of orientation of individual
plies and the size of load applied.
First order orthotropic shear deformation equations for the nonlinear elastic bending response of rectangular plates are introduced. Their solution using a computer program based on finite differences implementation of the Dynamic Relaxation (DR) method is outlined. The convergence and accuracy of the DR solutions for elastic large deflection response of isotropic, orthotropic, and laminated plates are established by comparison with various exact and approximate solutions. The present Dynamic Relaxation method (DR) coupled with finite differences method shows a fairly good agreement with other analytical and numerical methods used in the verification scheme.It was found that: The convergence and accuracy of the DR solution is dependent on several factors including boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR large deflection program using uniform finite differences meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads. All the comparison results for simply supported (SS4) edge conditions showed that deflection is almost dependent on the direction of the applied load or the arrangement of the layers
SRS to study Polytype NNN relationshipsDr Jim Kelly
This document discusses the use of synchrotron edge topography to study the relationships between different polytypes in silicon carbide (SiC). It provides background on polytypism in SiC, including different theories proposed to explain its occurrence. The document explains that synchrotron radiation is well-suited to study polytypes due to its high resolution. It describes how edge topography allows determining the spatial extent of disorder between polytypes and deducing their neighborhood relationships by superimposing Laue reflections. The technique reveals finer features at polytype boundaries like long period polytypes and one-dimensionally disordered layers.
This document analyzes the deflections and stresses in composite laminated plates using the dynamic relaxation method. It summarizes the following key points:
1) The dynamic relaxation method is used to solve the equilibrium equations for laminated plate deformation. This method converts the equations to dynamic form by adding damping and inertia terms.
2) Factors like shear deformation, length-to-thickness ratio, number of layers, material anisotropy, and fiber orientation affect plate deflection based on the analysis of square laminated plates with uniform loading.
3) Linear analysis overpredicts deflection compared to the dynamic relaxation method, which accounts for large deflections. Deflection depends on load size, ply orientation, and other
2021 v keshav non-linear stability and failure of laminated composite stiffen...ArpitaSaxena24
The document discusses the non-linear stability and failure of laminated composite stiffened cylindrical panels subjected to in-plane impulse loading. Finite element analysis is used to analyze the dynamic buckling behavior and first ply failure of laminated composite stiffened cylindrical panels under sinusoidal and rectangular pulse loads. The effects of loading duration and function, stiffener aspect ratio, and laminate stacking sequence on the nonlinear dynamic buckling load and first ply failure load are investigated. Key findings include composite stiffened panels exhibiting lower dynamic buckling loads than unstiffened panels for some stiffener geometries and loadings.
VARIATION OF MISMATCH-INDUCED STRESS IN A HETEROSTRUCTURE WITH CHANGING TEMPE...msejjournal
In this paper we analyzed influence of diffusion of material of an epitaxial layer of a heterostructure during
high-temperature growth into next layer (next epitaxial layer or substrate) of the heterostructure on mismatch-induced
stress. It has been shown, that value of mismatch-induced stress in heterostructure depends
on temperature of growth, because the considered diffusion depends on the temperature. We also introduce
an analytical approach to model the diffusion and relaxation of the mismatch-induced stress.
This document summarizes Michael Kreisel's dissertation on the connection between Gabor frames for quasicrystals, the topology of the hull of a quasicrystal, and K-theory of an associated twisted groupoid algebra. The author constructs a finitely generated projective module over this algebra, where any multiwindow Gabor frame for the quasicrystal can be used to construct a projection representing this module in K-theory. As an application, results are obtained on the twisted version of Bellissard's gap labeling conjecture for quasicrystals.
This document provides an overview of techniques for characterizing the structure of semi-crystalline polymers, including WAXS (wide-angle X-ray scattering) and SAXS (small-angle X-ray scattering). WAXS is used to determine the crystalline unit cell structure, while SAXS can measure the lamellar spacing between crystalline and amorphous regions. A correlation function analysis of SAXS data can provide additional structural information beyond just the lamellar spacing, such as the average crystal thickness and interfacial surface area. The degree of crystallinity can be estimated from WAXS, SAXS, or DSC measurements, but accuracy depends on the material's crystallinity level.
Space fullerenes: A computer search of new Frank-Kasper structuresMathieu Dutour Sikiric
Fullerenes are 3-valent plane graphs with faces of size 5 or 6. A space fullerene is a tiling of Euclidean space with fullerene tiles. The space fullerenes occur in metallurgy, bubble foams, and the solution of the Kelvin problem. Here we present enumeration techniques that allows to find many new space fullerenes.
A giant ring_like_structure_at_078_z_086_displayed_by_gr_bsSérgio Sacani
This document describes the discovery of a giant ring-like structure in the observable universe displayed by 9 gamma ray bursts (GRBs) between redshifts of 0.78 and 0.86. The ring has a diameter of 1720 Mpc, over five times larger than the expected transition scale to homogeneity. The ring lies at a distance of 2770 Mpc with major and minor diameters of 43° and 30°, respectively. The probability of this structure occurring by random chance is calculated to be 2 × 10-6. This ring-shaped feature contradicts the cosmological principle of large-scale homogeneity and isotropy, and the physical mechanism responsible is unknown.
Computational buckling of a three lobed crosectionprj_publication
The document summarizes a study on the computational buckling analysis of a cylindrical shell with a three-lobed cross-section of variable thickness under combined compression and bending loads. The shell's geometry and governing equations are modeled using thin-shell theory. The transfer matrix method is used to obtain the critical buckling loads and deformation modes for symmetrical and antisymmetrical buckling. Results show the buckling characteristics are sensitive to variations in thickness and radius along the shell's cross-section.
Using resonant ultrasound spectroscopy (RUS), the author will determine the complete elastic constant matrices of two thermoelectric single crystal samples, Ce.75Fe3CoSb12 and CeFe4Sb12. RUS involves measuring the resonant frequencies of a sample's vibrations, which depend on the sample's elastic constants, shape, orientation, and density. The author aims to obtain the elastic moduli from a single RUS spectrum for each sample. Understanding the elastic properties may help identify better thermoelectric materials by correlating low elastic stiffness with low thermal conductivity and higher thermoelectric efficiency. The author will compute the resonant frequencies using the samples' properties and compare to measurements.
Formation of low mass protostars and their circumstellar disksSérgio Sacani
Understanding circumstellar disks is of prime importance in astrophysics, however, their birth process remains poorly constrained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often wrapped into a sub-grid model, play a crucial role in disk formation and evolution. This calls for a combined approach in which both the protostar and circumstellar disk are studied in concert. Aims. We aim to elucidate the small scale physics and constrain sub-grid parameters commonly chosen in the literature by resolving the star-disk interaction. Methods. We carry out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe the collapse of a turbulent dense molecular cloud core to stellar densities. We study the birth of the protostar, the circumstellar disk, and its early evolution (< 6 yr after protostellar formation). Results. Following the second gravitational collapse, the nascent protostar quickly reaches breakup velocity and sheds its surface material, thus forming a hot (∼ 103 K), dense, and highly flared circumstellar disk. The protostar is embedded within the disk, such that material can flow without crossing any shock fronts. The circumstellar disk mass quickly exceeds that of the protostar, and its kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, and accretion onto the protostar mainly occurs through material that slides on the disk surface. The polar mass flux is negligible in comparison. The radiative behavior also displays a strong anisotropy, as the polar accretion shock is shown to be supercritical whereas its equatorial counterpart is subcritical. We also f ind a remarkable convergence of our results with respect to initial conditions. Conclusions. These results reveal the structure and kinematics in the smallest spatial scales relevant to protostellar and circumstellar disk evolution. They can be used to describe accretion onto regions commonly described by sub-grid models in simulations studying larger scale physics.
This document discusses crystal structures of inorganic oxoacid salts from the perspective of periodic graph theory and cation arrays. It analyzes 569 crystal structures of simple salts with the formulas My(LO3)z and My(XO4)z, where M are metal cations, L are nonmetal triangular anions, and X are nonmetal tetrahedral anions. The document finds that in about three-fourths of the structures, the cation arrays are topologically equivalent to binary compounds like NaCl, NiAs, and FeB. It proposes representing these oxoacid salts as a quasi-binary model My[L/X]z, where the cation arrays determine the crystal structure topology while the oxygens play a
Collective modes in the CFL phase - New Journal of Physics 13 (2011) 055002Roberto Anglani
This document summarizes a study of collective modes in the color flavor-locked (CFL) phase of dense quark matter. The authors derive the effective Lagrangian for the Nambu-Goldstone (NG) boson associated with spontaneous breaking of quark number symmetry, and determine corrections to previous results. They also derive the kinetic Lagrangian for the Higgs mode and interaction terms between the Higgs and NG fields using a Nambu-Jona-Lasinio model. This provides an effective description of low-energy excitations in the CFL phase to understand properties of compact stars containing quark matter.
This document is a dissertation by Joakim Carlsen submitted in 2014/2015 for a Bsc(Honours) in Applied Physics. It investigates detecting massive galaxies at high redshift (z > 4) using photometric data from the Dark Energy Survey (DES). The dissertation aims to identify massive galaxy candidates at z > 4 based on their colors and fit their spectral energy distributions using photometric redshift modeling software. Several high redshift massive galaxy candidates were identified and their properties were analyzed, with the most promising candidates to be proposed for follow-up spectroscopy to confirm their redshifts.
1) High-resolution N-body simulations were conducted of isolated disk galaxies to explore the origin of spiral arms. Mass concentrations similar to giant molecular clouds were included to perturb the disks.
2) The simulations demonstrated that the disks developed long-lived, multi-armed spiral structures in response to the perturbations. This challenges the expectation that spiral arms should fade quickly once perturbations are removed.
3) Contrary to linear theories of spiral structure formation, the response of the disks to local perturbations was found to be highly non-linear and time-variable, significantly modifying the formation and longevity of spiral patterns.
This document summarizes a numerical study of the structure and thermodynamics of colloidal suspensions using the variational method and integral equation theory. The interactions between colloid particles are modeled using either a Yukawa or Sogami potential. Results from the integral equation theory using a Sogami potential are found to be in good agreement with Monte Carlo simulation results and experimental data. The variational method and integral equation theory are used to calculate structural properties like the pair correlation function and thermodynamic properties.
Constraints on Ceres’ internal structure and evolution from its shape and gra...Sérgio Sacani
Ceres is the largest body in the asteroid belt with a radius of
approximately 470 km. In part due to its large mass, Ceres more closely approaches
hydrostatic equilibrium than major asteroids. Pre-Dawn mission
shape observations of Ceres revealed a shape consistent with a hydrostatic
ellipsoid of revolution. The Dawn spacecraft Framing Camera has been imaging
Ceres since March 2015, which has led to high-resolution shape models
of the dwarf planet, while the gravity field has been globally determined to
a spherical harmonic degree 14 (equivalent to a spatial wavelength of 211 km)
and locally to 18 (a wavelength of 164 km). We use these shape and gravity
models to constrain Ceres’ internal structure. We find a negative correlation
and admittance between topography and gravity at degree 2 and order
2. Low admittances between spherical harmonic degrees 3 and 16 are well
explained by Airy isostatic compensation mechanism. Different models of isostasy
give crustal densities between 1200 and 1400 kg=m3 with our preferred model
A new method is developed for determining material hardness from depth sensing indentation tests. Both loading and unloading data are used to calculate Meyer hardness values, which agree well with conventional optical measurements. While the new method characterizes hardness even for elastic materials, the conventional mean contact pressure definition differs significantly from hardness for elastic materials. A relationship is found between work during loading and unloading that allows hardness to be calculated using only load-depth data.
Dependence of Charge Carriers Mobility in the P-N-Heterojunctions on Composit...msejjournal
In this paper we consider manufacturing a p-n-junctions by dopant diffusion or ion implantation into a multilayer structure. We introduce an approach to increase sharpness of these p-n-junctions and at the same time to increase homogeneity of distributions of dopants in enriched by these dopants areas. We consider influence of the above changing of distribution of dopant on charge carrier mobility. We also consider an approach to decrease value of mismatch-induced stress in the considered multilayer structure by using a buffer layer. The decreasing gives a possibility to increase value of charge carrier mobility.
Dynamic Relaxation (DR) method is presented for the geometrically nonlinear laterally loaded,
rectangular laminated plates. The analysis uses the Mindlin plate theory which accounts for transverse
shear deformation. A computer program has been compiled. The convergence and accuracy of the DR
solutions for elastic large deflection response are established by comparison with various exact and
approximate solutions. New numerical results are generated for uniformly loaded square laminated
plates which serve to quantify the effects of shear deformation, length to thickness ratio, number of
layers, material anisotropy and fiber orientation.
It was found that linear analysis seriously over predicts deflection of plates. The shear
deflection depends greatly on a number of factors such as length to thickness ratio, degree of
anisotropy and number of layers. As the degree of anisotropy increases, the plate becomes stiffer and
when it is greater than a critical value, the deflection becomes virtually independent on the degree of
anisotropy. It was also found that deflection of plates depends on the angle of orientation of individual
plies and the size of load applied.
First order orthotropic shear deformation equations for the nonlinear elastic bending response of rectangular plates are introduced. Their solution using a computer program based on finite differences implementation of the Dynamic Relaxation (DR) method is outlined. The convergence and accuracy of the DR solutions for elastic large deflection response of isotropic, orthotropic, and laminated plates are established by comparison with various exact and approximate solutions. The present Dynamic Relaxation method (DR) coupled with finite differences method shows a fairly good agreement with other analytical and numerical methods used in the verification scheme.It was found that: The convergence and accuracy of the DR solution is dependent on several factors including boundary conditions, mesh size and type, fictitious densities, damping coefficients, time increment and applied load. Also, the DR large deflection program using uniform finite differences meshes can be employed in the analysis of different thicknesses for isotropic, orthotropic or laminated plates under uniform loads. All the comparison results for simply supported (SS4) edge conditions showed that deflection is almost dependent on the direction of the applied load or the arrangement of the layers
SRS to study Polytype NNN relationshipsDr Jim Kelly
This document discusses the use of synchrotron edge topography to study the relationships between different polytypes in silicon carbide (SiC). It provides background on polytypism in SiC, including different theories proposed to explain its occurrence. The document explains that synchrotron radiation is well-suited to study polytypes due to its high resolution. It describes how edge topography allows determining the spatial extent of disorder between polytypes and deducing their neighborhood relationships by superimposing Laue reflections. The technique reveals finer features at polytype boundaries like long period polytypes and one-dimensionally disordered layers.
This document analyzes the deflections and stresses in composite laminated plates using the dynamic relaxation method. It summarizes the following key points:
1) The dynamic relaxation method is used to solve the equilibrium equations for laminated plate deformation. This method converts the equations to dynamic form by adding damping and inertia terms.
2) Factors like shear deformation, length-to-thickness ratio, number of layers, material anisotropy, and fiber orientation affect plate deflection based on the analysis of square laminated plates with uniform loading.
3) Linear analysis overpredicts deflection compared to the dynamic relaxation method, which accounts for large deflections. Deflection depends on load size, ply orientation, and other
2021 v keshav non-linear stability and failure of laminated composite stiffen...ArpitaSaxena24
The document discusses the non-linear stability and failure of laminated composite stiffened cylindrical panels subjected to in-plane impulse loading. Finite element analysis is used to analyze the dynamic buckling behavior and first ply failure of laminated composite stiffened cylindrical panels under sinusoidal and rectangular pulse loads. The effects of loading duration and function, stiffener aspect ratio, and laminate stacking sequence on the nonlinear dynamic buckling load and first ply failure load are investigated. Key findings include composite stiffened panels exhibiting lower dynamic buckling loads than unstiffened panels for some stiffener geometries and loadings.
VARIATION OF MISMATCH-INDUCED STRESS IN A HETEROSTRUCTURE WITH CHANGING TEMPE...msejjournal
In this paper we analyzed influence of diffusion of material of an epitaxial layer of a heterostructure during
high-temperature growth into next layer (next epitaxial layer or substrate) of the heterostructure on mismatch-induced
stress. It has been shown, that value of mismatch-induced stress in heterostructure depends
on temperature of growth, because the considered diffusion depends on the temperature. We also introduce
an analytical approach to model the diffusion and relaxation of the mismatch-induced stress.
This document summarizes Michael Kreisel's dissertation on the connection between Gabor frames for quasicrystals, the topology of the hull of a quasicrystal, and K-theory of an associated twisted groupoid algebra. The author constructs a finitely generated projective module over this algebra, where any multiwindow Gabor frame for the quasicrystal can be used to construct a projection representing this module in K-theory. As an application, results are obtained on the twisted version of Bellissard's gap labeling conjecture for quasicrystals.
This document provides an overview of techniques for characterizing the structure of semi-crystalline polymers, including WAXS (wide-angle X-ray scattering) and SAXS (small-angle X-ray scattering). WAXS is used to determine the crystalline unit cell structure, while SAXS can measure the lamellar spacing between crystalline and amorphous regions. A correlation function analysis of SAXS data can provide additional structural information beyond just the lamellar spacing, such as the average crystal thickness and interfacial surface area. The degree of crystallinity can be estimated from WAXS, SAXS, or DSC measurements, but accuracy depends on the material's crystallinity level.
Space fullerenes: A computer search of new Frank-Kasper structuresMathieu Dutour Sikiric
Fullerenes are 3-valent plane graphs with faces of size 5 or 6. A space fullerene is a tiling of Euclidean space with fullerene tiles. The space fullerenes occur in metallurgy, bubble foams, and the solution of the Kelvin problem. Here we present enumeration techniques that allows to find many new space fullerenes.
A giant ring_like_structure_at_078_z_086_displayed_by_gr_bsSérgio Sacani
This document describes the discovery of a giant ring-like structure in the observable universe displayed by 9 gamma ray bursts (GRBs) between redshifts of 0.78 and 0.86. The ring has a diameter of 1720 Mpc, over five times larger than the expected transition scale to homogeneity. The ring lies at a distance of 2770 Mpc with major and minor diameters of 43° and 30°, respectively. The probability of this structure occurring by random chance is calculated to be 2 × 10-6. This ring-shaped feature contradicts the cosmological principle of large-scale homogeneity and isotropy, and the physical mechanism responsible is unknown.
Computational buckling of a three lobed crosectionprj_publication
The document summarizes a study on the computational buckling analysis of a cylindrical shell with a three-lobed cross-section of variable thickness under combined compression and bending loads. The shell's geometry and governing equations are modeled using thin-shell theory. The transfer matrix method is used to obtain the critical buckling loads and deformation modes for symmetrical and antisymmetrical buckling. Results show the buckling characteristics are sensitive to variations in thickness and radius along the shell's cross-section.
Using resonant ultrasound spectroscopy (RUS), the author will determine the complete elastic constant matrices of two thermoelectric single crystal samples, Ce.75Fe3CoSb12 and CeFe4Sb12. RUS involves measuring the resonant frequencies of a sample's vibrations, which depend on the sample's elastic constants, shape, orientation, and density. The author aims to obtain the elastic moduli from a single RUS spectrum for each sample. Understanding the elastic properties may help identify better thermoelectric materials by correlating low elastic stiffness with low thermal conductivity and higher thermoelectric efficiency. The author will compute the resonant frequencies using the samples' properties and compare to measurements.
Formation of low mass protostars and their circumstellar disksSérgio Sacani
Understanding circumstellar disks is of prime importance in astrophysics, however, their birth process remains poorly constrained due to observational and numerical challenges. Recent numerical works have shown that the small-scale physics, often wrapped into a sub-grid model, play a crucial role in disk formation and evolution. This calls for a combined approach in which both the protostar and circumstellar disk are studied in concert. Aims. We aim to elucidate the small scale physics and constrain sub-grid parameters commonly chosen in the literature by resolving the star-disk interaction. Methods. We carry out a set of very high resolution 3D radiative-hydrodynamics simulations that self-consistently describe the collapse of a turbulent dense molecular cloud core to stellar densities. We study the birth of the protostar, the circumstellar disk, and its early evolution (< 6 yr after protostellar formation). Results. Following the second gravitational collapse, the nascent protostar quickly reaches breakup velocity and sheds its surface material, thus forming a hot (∼ 103 K), dense, and highly flared circumstellar disk. The protostar is embedded within the disk, such that material can flow without crossing any shock fronts. The circumstellar disk mass quickly exceeds that of the protostar, and its kinematics are dominated by self-gravity. Accretion onto the disk is highly anisotropic, and accretion onto the protostar mainly occurs through material that slides on the disk surface. The polar mass flux is negligible in comparison. The radiative behavior also displays a strong anisotropy, as the polar accretion shock is shown to be supercritical whereas its equatorial counterpart is subcritical. We also f ind a remarkable convergence of our results with respect to initial conditions. Conclusions. These results reveal the structure and kinematics in the smallest spatial scales relevant to protostellar and circumstellar disk evolution. They can be used to describe accretion onto regions commonly described by sub-grid models in simulations studying larger scale physics.
This document discusses crystal structures of inorganic oxoacid salts from the perspective of periodic graph theory and cation arrays. It analyzes 569 crystal structures of simple salts with the formulas My(LO3)z and My(XO4)z, where M are metal cations, L are nonmetal triangular anions, and X are nonmetal tetrahedral anions. The document finds that in about three-fourths of the structures, the cation arrays are topologically equivalent to binary compounds like NaCl, NiAs, and FeB. It proposes representing these oxoacid salts as a quasi-binary model My[L/X]z, where the cation arrays determine the crystal structure topology while the oxygens play a
Collective modes in the CFL phase - New Journal of Physics 13 (2011) 055002Roberto Anglani
This document summarizes a study of collective modes in the color flavor-locked (CFL) phase of dense quark matter. The authors derive the effective Lagrangian for the Nambu-Goldstone (NG) boson associated with spontaneous breaking of quark number symmetry, and determine corrections to previous results. They also derive the kinetic Lagrangian for the Higgs mode and interaction terms between the Higgs and NG fields using a Nambu-Jona-Lasinio model. This provides an effective description of low-energy excitations in the CFL phase to understand properties of compact stars containing quark matter.
This document is a dissertation by Joakim Carlsen submitted in 2014/2015 for a Bsc(Honours) in Applied Physics. It investigates detecting massive galaxies at high redshift (z > 4) using photometric data from the Dark Energy Survey (DES). The dissertation aims to identify massive galaxy candidates at z > 4 based on their colors and fit their spectral energy distributions using photometric redshift modeling software. Several high redshift massive galaxy candidates were identified and their properties were analyzed, with the most promising candidates to be proposed for follow-up spectroscopy to confirm their redshifts.
1) High-resolution N-body simulations were conducted of isolated disk galaxies to explore the origin of spiral arms. Mass concentrations similar to giant molecular clouds were included to perturb the disks.
2) The simulations demonstrated that the disks developed long-lived, multi-armed spiral structures in response to the perturbations. This challenges the expectation that spiral arms should fade quickly once perturbations are removed.
3) Contrary to linear theories of spiral structure formation, the response of the disks to local perturbations was found to be highly non-linear and time-variable, significantly modifying the formation and longevity of spiral patterns.
This document summarizes a numerical study of the structure and thermodynamics of colloidal suspensions using the variational method and integral equation theory. The interactions between colloid particles are modeled using either a Yukawa or Sogami potential. Results from the integral equation theory using a Sogami potential are found to be in good agreement with Monte Carlo simulation results and experimental data. The variational method and integral equation theory are used to calculate structural properties like the pair correlation function and thermodynamic properties.
Constraints on Ceres’ internal structure and evolution from its shape and gra...Sérgio Sacani
Ceres is the largest body in the asteroid belt with a radius of
approximately 470 km. In part due to its large mass, Ceres more closely approaches
hydrostatic equilibrium than major asteroids. Pre-Dawn mission
shape observations of Ceres revealed a shape consistent with a hydrostatic
ellipsoid of revolution. The Dawn spacecraft Framing Camera has been imaging
Ceres since March 2015, which has led to high-resolution shape models
of the dwarf planet, while the gravity field has been globally determined to
a spherical harmonic degree 14 (equivalent to a spatial wavelength of 211 km)
and locally to 18 (a wavelength of 164 km). We use these shape and gravity
models to constrain Ceres’ internal structure. We find a negative correlation
and admittance between topography and gravity at degree 2 and order
2. Low admittances between spherical harmonic degrees 3 and 16 are well
explained by Airy isostatic compensation mechanism. Different models of isostasy
give crustal densities between 1200 and 1400 kg=m3 with our preferred model
This document describes a new algorithm for dual tree kernel conditional density estimation (KCDE) that provides fast and accurate density predictions. The algorithm extends previous work on univariate KCDE to allow for multivariate labels (Y) and conditioning variables (X). It applies Gray's dual tree approach separately to the numerator and denominator of the KCDE formula, and uses error bounds to ensure the quotient estimates have bounded relative error. This new algorithm provides the fastest known method for kernel conditional density estimation for prediction tasks.
This document provides an overview of crystallography concepts including:
- Lattices, unit cells, basis, packing, and the 14 Bravais lattices that describe crystal structures.
- Miller indices for describing directions and planes in crystal structures. Methods are described for determining Miller indices.
- Common crystal structures including ionic, covalent, metallic, and structures with more than one atom per lattice point.
- Polymorphism, allotropy, and polymorphic/allotropic transitions that can occur with changes in temperature and pressure.
End point of_black_ring_instabilities_and_the_weak_cosmic_censorship_conjectureSérgio Sacani
We produce the first concrete evidence that violation of the weak cosmic censorship conjecture can occur
in asymptotically flat spaces of five dimensions by numerically evolving perturbed black rings. For certain
thin rings, we identify a new, elastic-type instability dominating the evolution, causing the system to settle to
a spherical black hole. However, for sufficiently thin rings the Gregory-Laflamme mode is dominant, and the
instability unfolds similarly to that of black strings, where the horizon develops a structure of bulges connected
by necks which become ever thinner over time.
The discovery of a giant arc associated with the galaxy cluster IDCS J1426.5+3508 at z=1.75 is reported. HST imaging reveals an arc-like object with a length-to-width ratio greater than 10, located near the brightest cluster galaxy. Attempts to measure the redshift of the arc through spectroscopy were unsuccessful. The existence of such a massive, strongly lensing cluster at this early epoch poses challenges for the standard ΛCDM model of structure formation.
Late accretion of Ceres-like asteroids and their implantation into the outer ...Sérgio Sacani
This document summarizes research measuring visible and infrared spectra of 10 large, dark asteroids in the mid-outer main asteroid belt that are spectrally similar to Ceres. Thermal evolution modeling shows these "Ceres-like" asteroids have highly porous interiors, accreted relatively late between 1.5-3.5 million years after calcium-aluminum inclusions formed, and experienced maximum interior temperatures under 900K. Dynamical modeling suggests these asteroids were likely implanted from more distant regions into their current orbits between 3.0-3.4 AU during dynamical instability of the giant planets.
Large scale mass_distribution_in_the_illustris_simulationSérgio Sacani
Observations at low redshifts thus far fail to account for all of the baryons expected in the
Universe according to cosmological constraints. A large fraction of the baryons presumably
resides in a thin and warm–hot medium between the galaxies, where they are difficult to observe
due to their low densities and high temperatures. Cosmological simulations of structure
formation can be used to verify this picture and provide quantitative predictions for the distribution
of mass in different large-scale structure components. Here we study the distribution
of baryons and dark matter at different epochs using data from the Illustris simulation. We
identify regions of different dark matter density with the primary constituents of large-scale
structure, allowing us to measure mass and volume of haloes, filaments and voids. At redshift
zero, we find that 49 per cent of the dark matter and 23 per cent of the baryons are within
haloes more massive than the resolution limit of 2 × 108 M⊙. The filaments of the cosmic
web host a further 45 per cent of the dark matter and 46 per cent of the baryons. The remaining
31 per cent of the baryons reside in voids. The majority of these baryons have been transported
there through active galactic nuclei feedback. We note that the feedback model of Illustris
is too strong for heavy haloes, therefore it is likely that we are overestimating this amount.
Categorizing the baryons according to their density and temperature, we find that 17.8 per cent
of them are in a condensed state, 21.6 per cent are present as cold, diffuse gas, and 53.9 per cent
are found in the state of a warm–hot intergalactic medium.