Spherical Shell Research Articles

Superhydrophobic foam combined with biomass-derived TENG based on upcycled coconut husk for efficient oil-water separation.

The ocean ecological environments are seriously affected by oil spilling and plastic-debris, preventing and significantly reducing marine pollution via using biocomposite production from natural fiber reinforcement is a more friendly way to deal with marine oil pollution. Herein, we upcycled coir-coconut into lignin and coconut shell into spherical TENG by a combination of dip-dry and chemical treatment and used the SiO2 nanoparticles together with cellulose nanofibrils to prepare serial sugar-templated, anisotropic and hybrid foams. The as-prepared lignin/SiO2 porous sponge (LSPS) with a hierarchical porous morphology and uniformly dispersed nanoparticles structure benefits from the advantages of biomass-based additives, which presents reversible large-strain deformation (50%) and high compressive strength (11.42 kpa). Notably, the LSPS was significantly more hydrophobic (WCA ≈150°) than pure silicone-based foams, and its selective absorbability can separate oil from water under continuous pumping. Meanwhile, the coconut husk was also upcycled as a spherical TENG shell by a combination of the nanofiber-enhanced polymer spherical oscillator (CESO), which possessed high triboelectric properties (Uoc = 272 V, Isc = 14.5 μA, Q = 70 nC) and was comparable to the plastic shell TENG at low frequency (1.6 Hz). The monolithic foam structure developed using this clean synthetic strategy holds considerable promise for new applications in sustainable petroleum contamination remediation.

Large-scale synthesis of N-doped carbon spherical shells as high-performance cathode materials for Li–X (X = O2, S, Se) batteries

A cost-effective, reproducible, and scalable method to produce meso- and macro-porous hollow carbon spheres for high performance Li–X (X = O2, S, Se) batteries.

Compression and acceleration processes of spherical shells in gold cones

Abstract Double-cone ignition [Zhang et al., Phil. Trans. R. Soc. A 378, 20200015 (2020)] was proposed recently as a novel path for direct-drive inertial confinement fusion using high-power lasers. In this scheme, plasma jets with both high density and high velocity are required for collisions. Here we report preliminary experimental results obtained at the Shenguang-II upgrade laser facility, employing a CHCl shell in a gold cone irradiated with a two-ramp laser pulse. The CHCl shell was pre-compressed by the first laser ramp to a density of 3.75 g/cm3 along the isentropic path. Subsequently, the target was further compressed and accelerated by the second laser ramp in the cone. According to the simulations, the plasma jet reached a density of up to 15 g/cm3, while measurements indicated a velocity of 126.8 ± 17.1 km/s. The good agreements between experimental data and simulations are documented.

Advanced Frequency of Thick FGM Spherical Shells with Fully Homogeneous Equation by Using TSDT and Nonlinear Varied Shear Coefficient

Advanced Frequency of Thick FGM Spherical Shells with Fully Homogeneous Equation by Using TSDT and Nonlinear Varied Shear Coefficient

Diffuse sound field synthesis: Ideal source layers

Can uncorrelated surrounding sound sources be used to generate extended diffuse sound fields? By definition, targets are a constant sound pressure level, a vanishing active sound intensity, and uncorrelated sound waves arriving isotropically from all directions. Are there ideal source layouts to synthesize a maximum diffuse sound field within? As methods, we employ numeric simulations and undertake a series of considerations based on uncorrelated source layouts at a finite radius. Statistically expected active sound intensity and sound energy density are insightful and highlight the relation of active sound intensity to potential theory. Correspondingly, both Gauß’ divergence and Newton’s spherical shell theorem apply, and they provide valuable insights. In a circular layout, uncorrelated elementary point-source fields decaying by 1/√r ideally compose an extended sound field of vanishing active sound intensity; in spherical layouts this is the case with a 1/r decay. None of the layouts synthesizes a perfectly constant sound energy density inside. Theory and simulation offer a broad basis for understanding the synthesis of diffuse sound fields with uncorrelated sources in the free sound field.

Neutron capture reaction cross-section data processing and resonance parameter analysis of <sup>197</sup>Au based on white light neutron source

Neutron capture reaction is one of the neutron reactions and plays an important role in using reactor control rods and shell materials, designing nuclear device structures, and studying nuclear astrophysics S processes and element origins. The 4π BaF<sub>2</sub> detection device has advantages such as high time resolution, low neutron sensitivity, and high detection efficiency, thus making it suitable for measuring neutron radiation capture reaction cross-section data. In order to fill the gap in our neutron capture reaction data in the keV energy range and improve their accuracy, the Key Laboratory of Nuclear Data at the Chinese Institute of Atomic Energy (CIAE) has established a Gamma Total Absorption Facility (GTAF), which consists of 28 hexagonal BaF<sub>2</sub> crystals and 12 pentagonal BaF<sub>2</sub> crystals to form a spherical shell with an external diameter of 25 cm and an internal diameter of 10 cm, covering 95.2% of the solid angles. The Back-n beam line of the Chinese Spallation Neutron Source (CSNS) is a back-streaming white beam line that covers neutron energy ranging from a few eV to several hundred MeV, making it suitable for measuring neutron capture cross-sections. The reaction cross-section data of <sup>197</sup>Au is measured by using GTAF on the Back-n beam line. The measurement data are preliminarily background deducted through energy screening, PSD method, and crystal multiplicity screening. Subsequently, the background is analyzed and deducted based on the measurement data of <sup>nat</sup>C and empty samples, and the yield of <sup>197</sup>Au capture reaction is obtained. Resonance parameters are a set of parameters extracted from experimental data to describe the resonance curve, which can eliminate the influence of experimental conditions on resonance data and are more important than the cross-section obtained from experiments. The resonance energy, neutron resonance width, and gamma resonance width parameters of <sup>197</sup>Au at 1–100 eV are fitted by using the SAMMY program. From the comparison between the resonance curves obtained from experimental measurements and the resonance parameters obtained from fitting with the ENDF/B-VIII.0 database, it can follow that the experimental measurement results are in good agreement with the database, nevertheless, there exist some differences in the resonance parameter, which may be due to the GTAF energy resolution, Back-n neutron spectrum measurement accuracy, and the experimental background deduction method. Our next work is to identify the sources of difference.

Keplerian Motion Inside an Isolated Dark Matter Halo and the Hubble’s Law

Recently, the existence of a new kind of staff, named “Zaman”, responsible for time variation by its spin, was established. The proposed model offered a suitable solution for the Dark Matter enigma. In this work, we generalize the previously solid body rotating spherical halo U to a differential rotation, where each spherical shell of radius R has a length of the day T(R) related to R with the Kepler’s relation: . We prove that the linear Hubble’s relation, , is just a consequence of our new “time”-model, and does not need any special hypothesis nor any special non Euclidean topology on U.

EQUATIONS OF MOTION OF AN ISOTROPIC SPHERICAL MOMENT ELASTIC SHELL*2

Using the previously obtained equations of motion of thin moment elastic shells of constant thickness with an arbitrary middle surface, the equations of motion of an isotropic moment spherical shell in terms of forces and “displacements” (kinematic parameters) are constructed. In this case, the metric of the middle spherical surface is taken into account, as the curvilinear coordinates of which two angular coordinates of the standard spherical coordinate system with the origin at the center of the middle surface are used. First, a closed system is written down, which includes the equations of motion in the physical components of the tensors of internal forces and moments, as well as additional similar characteristics corresponding to the moment properties of the model, and physical relationships. Then, by excluding physical relations, it is reduced to twelve equations of motion in kinematic parameters, written in operator form. In this case, the coefficients of partial derivative operators are simplified by neglecting terms that have a higher order of smallness relative to the thickness of the shell. Despite the bulkiness of the system, it is written in a compact form. Boundary conditions are not written, since the shell is considered closed. By introducing additional hypotheses similar to those used in the classical theory of shells (neglecting the compression of a normal fiber, the Kirchhoff – Love hypothesis about the connection between the tangential components of the rotation angle vector of a normal fiber and normal displacement, as well as the hypothesis about the connection between the normal to the middle surface part of the coordinate of the rotation angle vector and its tangential components) the number of equations and unknowns decreases. To carry out this procedure, a variational Hamilton equation is constructed, which takes into account the connections between kinematic parameters imposed by the hypotheses, and then the corresponding one is transformed using the generalized Ostrogradsky – Gauss theorem.

Mechanical Properties of Hot-Stamped Spherical Shell Q235 Steel after Exposure to Elevated Temperature

Mechanical Properties of Hot-Stamped Spherical Shell Q235 Steel after Exposure to Elevated Temperature

Study on yield limit of steel containment under external pressure considering initial defects

The main objective of floating nuclear power plants (FNPP) is an emerging technology product formed by applying land small-scale nuclear power plant technology to the marine field. The containment structure studied in this article plays a great role in protecting the safety of FNPP’s nuclear power system. When exploring the safety performance of the containment structure under accident conditions, it is necessary to analyze and study the external pressure yield limit of the containment. This study provides a reference basis for the static buckling limit calculation of spherical shell structures similar to steel safety shells. The article adopts a geometric initial defect analysis method based on buckling mode to consider the initial defects of the model and explores the external pressure yield limit of the safety shell through the arc length method. The research results analyzed that the external pressure yield limit of the containment vessel decreased by about 30% under the influence of initial defects and pointed out the weak structural parts of the containment vessel in the buckling analysis.

Reactant enrichment in yolk-shell structured Pd/TiN nanoreactors for boosting electrocatalytic hydrodechlorination performance

Enhancing the enrichment behavior of low-concentration chlorinated organic pollutants remains a significant challenge in electrocatalytic hydrodechlorination (EHDC) technology. Metal-loaded hollow nanoarchitecture has emerged as a promising nanoreactor to improve reaction enrichment behavior because of its tailorable microenvironments and electronic properties. Herein, a structural engineering strategy is developed to synthesize yolk-shell structured TiN spheres supported Pd nanoreactors (Pd/YS-TiN) with confined mesoscopic spaces. Characterization by multiple techniques reveals that the yolk-shell structure of YS-TiN, with high specific surface area (139.0 m2/g) and appropriately mesoporosity (6.9 nm), exposes numerous Pd nanoparticles (∼4.0 nm) on outer/inner surface of the shell and yolk-core solid sphere, ensuring an efficient utilization of active sites for enhancing the 2,4-DCP detoxification. Consequently, the structurally optimized Pd/YS-TiN nanoreactor consistently displays maximum reaction kinetics, dechlorination degree, faradaic current density, H* utilization and product selectivity, surpassing hollow TiN-supported Pd and Pd/C catalysts. The super EHDC performance of 91.8 % 2,4-DCP conversion, a specific activity of 1.68 min−1 molPd−1, and a mass activity of 6.06 min−1 gPd−1 is obtained at −0.85 V and 180 min, outperforming most reported catalysts. Combining experimental and density functional theory results, the exceptional reaction enrichment behavior of Pd/YS-TiN originates from (1) alleviating the overstrong adsorption of product phenol through strong metal-support interactions and (2) enhancing mass transport efficiency facilitated by the local concentration gradient and mesoporous shell. This study elucidates how metal-support interactions and mass transport synergistically enhance reaction enrichment behavior, showcasing potential benefits in environmental remediation applications.

Giant Raman radiation from molecules in a spherical metal shell

The work considers an electrodynamic model of radiation from molecules placed in a metal shell. The model qualitatively describes the enhancement of the surface-enhanced Raman scattering (SERS) signal from spherical nanoparticles coated with a thin silver film. The change in the SERS signal is calculated depending on the thickness of the metal nanolayer on top of the spherical particles. The radiating molecular dipole interacts with the metal shell and excites surface plasmons. Plasmonic oscillations reach a maximum when the frequency of the dipole is close to the plasmon resonance of the metal shell, and the dipole itself is close to the plasmonic shell. It has been theoretically shown that the intensity of secondary radiation generated by spherical nanoparticles coated with a silver film several nanometers thick can reach up to six or more orders of magnitude. The effect of a tenfold amplification of the SERS signal was experimentally demonstrated using the example of a large ensemble of single polystyrene microspheres with an average diameter of about 300 nm, coated with a silver nanolayer, which have characteristic Stokes frequencies of 1001 cm-1, 1602 cm-1. We believe that the tenfold enhancement of Raman scattering is due to the electromagnetic amplification mechanism.

Thermo‐electrohydrodynamic convection in the thermally driven spherical shell with differential rotation

AbstractThis study investigates thermo‐electrohydrodynamics (TEHD) convection in the thermally driven spherical shell with differential shell rotation. The TEHD convection is induced by an electric tension applied at the inner spherical shell whereas the outer shell is grounded. Hence, an electric central force field is present similar to terrestrial gravity in a planetary system. Spherical rotation mimics planetary rotation and is used to investigate the convective nature of the spherical gap. The results demonstrate four main convective regimes that depend on the strength of the electric tension and rotational forcing. The convective pattern formation is investigated by a Hammer‐Aitov projection, the radial and meridional velocity components to indicate convective or advective fluid motion related to the individual forcing. The heat transfer is characterised by the Nusselt number and showed a strong dependence on the forcing.

Confining Co1.11Te2 nanoparticles within mesoporous hollow carbon combination sphere for fast and ultralong sodium storage

Co1.11Te2 nanoparticles are in-situ uniformly grown within mesoporous hollow carbon combination sphere (MHCCS@Co1.11Te2) using a hard-template and spray drying process, solution impregnation and pyrolysis tellurization. Material characterizations reveal that Co1.11Te2, with a diameter of ∼ 20 nm, is attached to the internal walls of the unit spheres or embedded in the mesopore shells of the unit spheres, presenting a distinctive “ships-in-combination-bottles” nanoencapsulation structure. In sodium-ion half-cells, MHCCS@Co1.11Te2 exhibits excellent cycling stability, achieving reversible capacities of 257 mAh/g at 0.5 A/g after 250 cycles, 235 mAh/g at 1.0 A/g after 300 cycles and 161 mAh/g at 10.0 A/g after 1900 cycles. Electrochemical kinetic analyses and ex-situ characterizations reveal rapid electron/Na+ transport kinetics, prominent surface pseudocapacitive behavior, robust nanocomposite structure, and multi-step conversion reactions of sodium polytellurides. In sodium-ion full-cells, MHCCS@Co1.11Te2 still demonstrates stable cycling performance at 1.0 and 5.0 A/g and excellent rate capability. The superior electrochemical performance is associated with the nanoencapsulation structure based on mesoporous hollow carbon combination spheres, which promotes electron conduction and Na+ transport. The space-confined effect maintains the high electrochemical activity and cycling stability of Co1.11Te2.

Thermally Induced Vibrations of Functionally Graded Shallow Spherical Shells Under Cooling Shock

Based on the first-order shear deformation theory (FSDT), the large-amplitude vibration behavior of shallow spherical shells made of functionally graded materials (FGMs) due to the rapid decrease of temperature (cooling shock) is investigated. FGM is assumed to be a mixture of stainless steel and low-carbon steel whose properties are considered temperature dependent and are estimated based on the power-law model. According to FSDT and von Kármán assumptions, the governing equations of motion in conjunction with corresponding boundary conditions are obtained using Hamilton’s principle. The temperature distribution is also achieved by means of the 1D Fourier transient heat conduction equation, considering two time-dependent thermal loading scenarios. The considered thermal boundary conditions allow that a temperature difference is created with a time delay for the structure under cooling shock. Also, the results of recent experiments are employed to estimate the temperature-dependent properties of structures. In the solution approach, the generalized differential quadrature method and the Newmark-beta integration scheme are utilized. Selected numerical results are presented to study the effects of thermal load rapidity time, geometry, magnitude of thermal load, and material gradient index on the thermally induced vibrations of spherical shells. Stresses generated in the shell due to the thermally induced vibrations are also investigated.

Thin-walled tapered conformable low-pressure tanks: Concept and principles

In pressure tank design, structural efficiency or the ratio of pressurized volume to structural mass is fundamental and implies a specific shape, such as a cylindrical or spherical layout. However, this axi-symmetric layout may be not conform to the enveloping shape. Previous investigations developed a conformable tank concept with a multi-bubble axi-symmetric layout, called a multi-lobe, multi-cell or multi-bubble tank, but structural design and analysis are limited to intersecting cylindrical, spherical or toroidal shells. The objective of this research is to increase the volumetric efficiency of multi-bubble tanks even further through the introduction of a conical shell. An integral analytical formulation of tank topology and explicit expression of equilibrium are provided in order to design a structurally efficient tapered multi-bubble tank under low differential pressure. The result is expressed in a geometric rule that is applicable for tapered multi-bubble tanks of any eligible shape.

Magnetron sputter deposition of ultrathick boron carbide coatings on spherical substrates for inertial confinement fusion

Most designs of inertial confinement fusion (ICF) targets require ablators in the form of hollow spherical shells with an outer diameter of ∼1−3 mm and a wall thickness of ∼20−200 microns. Vapor deposition onto rolling spherical substrates (templates) is the generally preferred method for the fabrication of ICF ablators. Amorphous boron carbide (B4C) is a promising material for use as an ablator due to its favorable properties. However, the challenge lies in creating ultrathick B4C coatings with submicron-scale density uniformity on rolling spherical substrates. Here, we show examples from our ongoing systematic study of the deposition of B4C onto 2-mm-diameter Si spheres by radio-frequency magnetron sputtering (RFMS). We start with a RFMS recipe developed for depositing planar amorphous B4C films with close-to-zero residual stress and transfer the deposition process from stationary planar substrates to rolling spherical substrates. A major challenge of the deposition onto rolling spheres is preventing the formation of so-called nodular defects, attributed to the incorporation of particulates into the growing film. To address this challenge, we explore ways to minimize the generation and accumulation of particulates on the substrate holder by a combination of enhanced film adhesion to the substrate holder surface and removal of particulates from the holder area where spherical substrates are rolling. With this approach, we demonstrate the deposition of an ∼75-micron-thick B4C coating on a Si sphere.

Explosions of Ball Lightning inside Enclosed Spaces

According to observations, the energy density contained inside ball lightning can reach 1010 J/m3, and its charge can range from 10−3 to 10−1 C. Witnesses often report seeing moving sparks about one millimeter in size inside the ball lightning shell. When the ball lightning shell ruptures, charge carriers fly out of it in the form of a sheaf of sparks. For many years, the press has published reports of the destruction of houses inside of which a ball lightning explosion had occurred. These events remained unexplained for a long time. This article, for the first time in the world, provides a physical explanation of these events. This article is based on the ball lightning model developed by the authors. According to this model, ball lightning consists of an ensemble of positively charged elements (dynamic electric capacitors) located inside a spherical shell of polarized water molecules. The dynamic capacitor is a system of cyclically moving electrons and ions. The expansion of this capacitor is restrained by the compression force of the ball lightning shell in the non-uniform electric field of the ball lightning core. The model allows us to find a physical explanation for most of the observed properties of ball lightning. Using the example of a simplified model of ball lightning (when the contribution of the kinetic energy of the dynamic capacitors was not taken into account), an analysis of the forces acting inside ball lightning was carried out. It was shown that when the shell of ball lightning is destroyed, the charges emitted from the core remain on the walls of the room or on loose objects for some time. The Coulomb force of the repulsion of charges turns out to be large enough to squeeze out the walls of a building or throw a heavy object or person out of the house.

Quasi-geostrophic convection-driven dynamos in a thick spherical shell

SUMMARY We present dynamos computed using a hybrid QG-3D numerical scheme in a thick spherical shell geometry. Our model is based on a quasi-geostrophic convection code extended with a 3-D treatment of heat transport and magnetic induction. We find a collection of self-sustained, multipolar, weak field dynamos with magnetic energy one or two orders of magnitude lower than the kinetic energy. The poloidal magnetic energy is weak and, by construction, there is a lack of equatorially antisymmetric components in the Buoyancy and Lorentz forces. This leads to configurations where the velocity field is only weakly impacted by the magnetic field, similar to dynamos found in 3-D simulations where zonal flows and the Ω-effect dominate. The time-dependence of these dynamos is characterized by quasi-periodic oscillations that we attribute to dynamo waves. The QG-3D dynamos found so far are not Earth-like. The inability of our setup to produce strong, dipole-dominated, magnetic fields likely points to a missing ingredient in our QG flows, and a related lack of helicity and α-effect. The models presented here may be more relevant for studying stellar dynamos where zonal flows are known to dominate. This study was carried out at modest control parameters, however moving to lower Ekman numbers, when smaller values of both the magnetic and hydrodynamic Prandtl numbers can be of interest, our approach will be able to gain in efficiency by using relatively coarse grids for the 3-D magnetic and temperature fields and a finer grid for the QG velocity field.

Free vibration analysis of FGM spherical and elliptical shells under nonlinear thermal environments

The thermo-mechanical effects of the free vibration of functionally graded (FG) spherical and elliptical shells under nonlinear temperature distributions (NTD) are investigated. The geometries of the FG spherical and elliptical shells are expressed in terms of the surface fundamental form, and the displacement function is derived based on higher-order shear deformation theory (HSDT). Temperature-dependent (TD) material and heat conduction are investigated based on Voigt's micromechanical model. The equation of motion of the thermo-elastic FG shells is formulated using the classical Hamilton's principle. Numerical results are obtained using the finite element method with quadrilateral Lagrangian isoparametric elements. A comparison of the results for the free vibration of FG shells based on the FSDT and HSDT approaches is presented. The first fundamental mode is the axisymmetric mode for the circular plate and oblate shell, but the results are otherwise for spherical and prolate shells. The torsional mode occurs in the seventh mode within the first ten vibrational modes for the prolate shell. In addition, the frequency parameter in the torsional mode is independent of the different support conditions. Parametric studies show that the non-dimensional frequency parameters of the FG shells decrease quickly, then slowly, as the volume fraction index increases. Finally, the frequency parameters decrease when the temperature at the top of the FG shell surface increases.