Energy Shell Research Articles

Improved Lifetime Model of Energetic Electrons Due to Their Interactions With Chorus Waves

AbstractChorus waves induce both electron acceleration and loss. In this letter, we provide significantly improved models of electron lifetime due to interactions with chorus waves. The new models fill the gap that previous models have on some magnetic local time (MLT) sectors of the Earth's magnetosphere. This improvement is critical for modeling studies. The lifetime models developed using two different methods are valid for electrons with an energy range from 1 keV to 2 MeV. To facilitate the integration of these new models into different ring current and radiation belt codes, we parameterize the electron lifetime as a function of ‐shell and electron kinetic energy at each MLT and geomagnetic activity (Kp). The parameterized electron lifetimes exhibit strong dependencies on ‐shell, MLT, and energy. Simulations using these new models demonstrate improved agreement with satellite observations compared to simulations using previous models, advancing our understanding of electron dynamics in the magnetosphere.

Evolution of low-mode asymmetries introduced by x-ray P2 drive asymmetry during double shell implosions on the SG facility

Abstract Double shell capsule can provide a potential low-convergence to fusion ignition at relatively low temperature (∼3 keV). One of the main sources of degrading double shell implosion performance is the low-mode asymmetries. Recently, the experiments on the evolution of low-mode asymmetries introduced by x-ray P2 drive asymmetry during double shell implosions were carried out on the SG facility, where the outer shell and inner shell shapes were measured through the backlit radiography, and the fuel shape near stagnation was measured by core x-ray self-emission imaging. The time-dependent x-ray flux symmetry was controlled by varying the inner cone fraction, defined as the ratio of the inner cone power to the total laser power, while keeping the drive temperature histories same across experiments. Both the hohlraum radiation and the capsule implosions were analyzed using a two-dimensional radiation-hydrodynamics code. Comparing the experimental radiographs and self-emission images to the simulations, it is found that the simulated outer shell, inner shell and hot spot shapes are in qualitative agreement with experiments, especially, the symmetry swings of the hot spot shape near stagnation are observed from both experimental and simulation results. Further, the effect of x-ray drive asymmetries on double shell implosion performance is preliminarily investigated using numerical simulations. We find that the azimuthal variations in radial velocity caused by drive asymmetries can generate azimuthal mass flow of the inner shell, thus kinetic energy of the inner shell would be not converted into fuel internal energy with high efficiency, and the mass-averaged ion temperature of the fuel at stagnation would be reduced.

Cutoff Ergodicity Bounds in Wasserstein Distance for a Viscous Energy Shell Model with Lévy Noise

This article establishes explicit non-asymptotic ergodic bounds in the renormalized Wasserstein–Kantorovich–Rubinstein (WKR) distance for a viscous energy shell lattice model of turbulence with random energy injection. The system under consideration is driven either by a Brownian motion, a symmetric α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document}-stable Lévy process, a stationary Gaussian or α\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha $$\\end{document}-stable Ornstein–Uhlenbeck process, or by a general Lévy process with second moments. The obtained non-asymptotic bounds establish asymptotically abrupt thermalization. The analysis is based on the explicit representation of the solution of the system in terms of convolutions of Bessel functions.

The importance of natural land carbon sinks in modelling future emissions pathways and assessing individual country progress towards net-zero emissions targets

Nature-based solutions (NBS), in the form of active ecosystem conservation, restoration and improved land management, represent a pathway to accelerate net-zero emissions (NZE) strategies and support biodiversity. Meaningful implementation and successful accounting depend on the ability to differentiate between anthropogenic and natural carbon fluxes on land. The United Nations Framework Convention on Climate Change (UNFCCC) land carbon accounting methods currently incorporate all CO2 fluxes on managed land in country inventories without distinguishing between anthropogenic and natural components. Meanwhile, natural land carbon sinks are modelled by earth system models but are mostly reported at global level. Here we present a simple yet novel methodology to estimate the present and future progression of natural land sinks at the country and regional level. Forests dominate the uptake of CO2 on land and as such, our analysis is based on allocating global projections of the natural land carbon flux to individual countries using a compilation of forest land areas for a historic and scenario range spanning 1960–2100. Specifically, we use MIT’s carbon cycle model simulations that are set in the context of emissions pathways from the Shell Energy Security Scenarios (2023). Our natural land carbon flux estimates for individual countries and regions such as the European Union (EU) show generally good agreement with independent estimates from recent land-use harmonisation studies for 2000–2020. Hence, our approach may also provide a simple, first-order exploration of future natural land fluxes at country level—a potential that other studies do not yet offer. In turn, this enables better understanding of the anthropogenic and natural components contributing to country NZE targets under different scenarios. Nevertheless, our findings also suggest that models such as the Shell World Energy Model (WEM) would benefit from further improvements in the apportionment of land carbon sources and sinks to evaluate detailed actions to meet country targets. More importantly, uncertainties remain regarding the resilience of land ecosystems and their capacity to store increasing amounts of carbon under progressive global warming. Therefore, we recommend that the carbon cycle modelling and energy modelling research communities continue to collaborate to develop a next generation of relevant data products to distinguish anthropogenic from natural impacts at local, regional and national levels.

An adaptive suspended-dome structure: Static control methods based on minimum strain energy

The suspended-dome structure is a rigid-flexible and pre-stressed space structure composed of grid shells, cable and struts. It is widely used in large-span space structures for its efficient mechanical properties. The emergence of adaptive structure enables the structure to change its shape and stiffness according to the change of external environment, realizing light weight, high efficiency and intelligence of the structure. The concept of adaptivity is introduced into the traditional suspended-dome structure, presenting an Adaptive Suspended-Dome Structure (ASDS) where actuators replace the struts. A static control method utilizing a multi-population gradient genetic algorithm based on a strain energy optimization control model is proposed and developed in terms of control model research, control algorithm theory, and control effects. Specifically, an ASDS control optimization model is established with the adjustment values of the actuators as control variables and the strain energy of the upper grid shell as the objective function. The multi-population gradient genetic algorithm is improved to overcome the premature convergence problem of traditional genetic algorithms, further enhancing the search speed. A numerical simulation of a suspended-dome structure model with a span of 12 m, an aspect ratio of 10, and equipped with 16 actuator struts is featured. The overall strain energy of the controlled structure is reduced by about 40 % at maximum and the sum of squared displacements is reduced by nearly 41 % at maximum, which verifies the adaptability of ASDS to loads and the effectiveness of the control method. The suspended-dome structure of Jinan Olympic Sports Center Gymnasium is selected for data simulation to verify the effectiveness and application value of ASDS in engineering. The research methodology and conclusions provide valuable references for the design and control of adaptive structures.

An asymptotically consistent morphoelastic shell model for compressible biological structures with finite-strain deformations

We derive an asymptotically consistent morphoelastic shell model to describe the finite deformations of biological tissues using the variational asymptotic method. Biological materials may exhibit remarkable compressibility when under large deformations, and we take this factor into account for accurate predictions of their morphoelastic changes. The morphoelastic shell model combines the growth model of Rodriguez et al. and a novel shell model developed by us. We start from the three-dimensional (3D) morphoelastic model and construct the optimal shell energy based on a series expansion around the middle surface. A two-step variational method is applied that retains the leading-order expansion coefficient while eliminating the higher-order ones. The main outcome is a two-dimensional (2D) shell energy depending on the stretching and bending strains of the middle surface. The derived morphoelastic shell model is asymptotically consistent with three-dimensional morphoelasticity and can recover various shell models in literature. Several examples are shown for the verification and illustration.

Enhanced dielectric properties of nanocomposites with cyanoethyl cellulose and core‐shell structured BaTiO3@Al2O3 fillers

AbstractThe interface between the polymer matrix and inorganic fillers plays a determinative role in dielectric properties of the composites. In this work, dielectric composites containing core‐shell structured BaTiO3@Al2O3 (BT@AO) nanoparticles and cyano functionalized cellulose (cyanoethyl cellulose, CEC) were prepared to achieve enhanced interface and dielectric properties. With the wide bandgap Al2O3 (AO) shell, the carrier motion inspired by elevating electric filed and temperature was significantly impeded in the composites. Meanwhile, the moderate dielectric constant and surface energy of AO shell between CEC and BaTiO3 (BT) alleviated the inhomogeneous local electric field distribution and improve the interfacial compatibility between inorganic filler and CEC matrix. As a result, enhanced dielectric properties including restrained dielectric loss (0.23 for BT@AO/CEC versus 0.51 for BT/CEC at 100 Hz), suppressed conductivity, increased breakdown strength and improved dielectric constant were accessed in the BT@AO/CEC composites. The excellent thermal conductivity of AO also offered the composites with additional advantage of low electrical conductivity at high temperature of 100°C (1.56 × 10−10 S/cm) exhibiting two orders of magnitude smaller than that of pure CEC.Highlights Core‐shell structured BaTiO3@Al2O3 were prepared and incorporated into cyanoethylated cellulose to yield flexible nanocomposites. Carrier motion was significantly restricted by the wide band gap of Al2O3 shell. Enhanced interfacial compatibility was accessed in the BaTiO3@Al2O3/CEC composite. Improved dielectric properties and thermal conductivity were achieved.

Improving the performance of a shell and tube latent heat thermal energy storage through modifications of heat transfer pipes: A comprehensive investigation on various configurations

The modification of the geometric configurations of heat transfer pipes in shell and tube Latent Heat Thermal Energy Storage (LHTES) systems not only enhances the melting process of the phase change material (PCM) but also improves the overall performance of these systems. This study aims to investigate ways to enhance the performance of LHTES systems by employing heat transfer pipes with various fin and twisted tape arrangements in a horizontal orientation. The Finite Volume Method and Enthalpy-Porosity method are employed to simulate the melting process. Stearic acid is used as the PCM material, while water serves as the heat transfer fluid. Eight different geometric configurations are modelled in the LHTES system: base case, horizontal fins, vertical fins, helical fins, horizontal tape, vertical tape, twisted tape and helical fins with twisted tape. The results show that within the time range of 0 and 29 min, the combined configuration of helical fins with twisted tape consistently demonstrates the fastest melting process. After 29 min, the configuration with vertical fins exhibits a marginally faster melting process than the combined configuration of helical fins with twisted tape. The configurations involving tapes also contribute to accelerated melting, although to a lesser extent than those with fins. Particularly, twisted tape proves highly effective in facilitating faster melting. The complete melting process times for configurations with vertical fins, helical fins, and combined helical fins with twisted tape are 38.7 %, 23.5 % and 32.7 % faster compared to the base case which is ∼69 min. Among the configurations, using tapes results in higher flow resistance and surface area compared to the base case. The attractive features of these configurations make them ideal for creating efficient and space-saving energy storage systems. This study provides crucial insights into essential heat and mass transfer processes, which can be leveraged to develop advanced LHTES systems for enhanced performance and sustainable energy solutions.

Physical mechanisms for dependence of temperature-induced phase transition and shape memory effect on grain size in nanocrystalline NiTi shape memory alloys

Physical mechanisms for dependence of temperature-induced phase transition and shape memory effect (SME) on grain size (GS) of nanocrystalline NiTi shape memory alloys (SMAs) were revealed by combining experiment and molecular dynamics simulation. Influences of GS on phase transition temperature and stress level during tension loading below martensite transition finish temperature Mf are interpreted by core-shell theory that energy of shell (grain boundary (GB)) is higher than that of core (grain interior), so shell becomes an obstacle to deformation of the core and the obstacle increases with reducing GS because the fraction of GB increases with decreasing GS. Due to the constraint of shell, martensite transition during cooling is so incomplete that stress-induced martensite occurs in nanocrystalline NiTi SMAs deformed below Mf. After unloading, some stress-induced martensite phases are retained due to the lack of driving force for reverse martensite transition at low temperature. This is why SME occurs in the alloy with GS below 10 nm when no temperature-induced phase transition happens. Under the same tension strain, inelastic strain after unloading increases with increasing GS. The increase of GS causes the increase of SME strain, and the residual strain after heating the deformed nanocrystalline NiTi SMAs stems from the plastic deformation of martensite and austenite in grain interior during tension.

Phase space geometry of general quantum energy transitions

The mixed density operator for coarsegrained eigenlevels of a static Hamiltonian is represented in phase space by the spectral Wigner function, which has its peak on the corresponding classical energy shell. The action of trajectory segments along the shell determine the phase of the Wigner oscillations in its interior. The classical transitions between any pair of energy shells, driven by a general external time dependent Hamiltonian, also have a smooth probability density. It is shown here that a further contribution to the transition between the corresponding pair of coarsegrained energy levels, which oscillates with either energy, or the driving time, is determined by four trajectory segments (two in the pair of energy shells and two generated by the driving Hamiltonian) that join exactly to form a closed compound orbit (CCO). In its turn, this sequence of segments belongs to the semiclassical expression of a compound unitary operator that combines four quantum evolutions: a pair generated by the static internal Hamiltonian and a pair generated by the driving Hamiltonian. The CCOs are shown to belong to continuous families, which are initially seeded at points where the classical flow generated by both Hamiltonians commute.

Patterning of multicomponent elastic shells by gaussian curvature.

Recent findings suggest that shell protein distribution and the morphology of bacterial microcompartments regulate the chemical fluxes facilitating reactions which dictate their biological function. We explore how the morphology and component patterning are coupled through the competition of mean and gaussian bending energies in multicomponent elastic shells that form three-component irregular polyhedra. We observe two softer components with lower bending rigidities allocated on the edges and vertices while the harder component occupies the faces. When subjected to a nonzero interfacial line tension, the two softer components further separate and pattern into subdomains that are mediated by the gaussian curvature. We find that this degree of fractionation is maximized when there is a weaker line tension and when the ratio of bending rigidities between the two softer domains ≈2. Our results reveal a patterning mechanism in multicomponent shells that can capture the observed morphologies of bacterial microcompartments, and moreover, can be realized in synthetic vesicles.

Comparative analysis on melting performance of PCM using rectangular and branching fin configurations in a shell and tube type thermal energy storing unit

Phase change materials (PCMs) are widely used in various applications, however, their low conductivity and long phase transition time hinder thermal energy supply. Thus, numerous researchers have studied various fin designs to solve this problem. In this study, with the unique combinations of two, three and four rectangular fins and straight, curved and angled branching fins, nine novel cases have been proposed to examine the melting enhancement of PCM in shell and tube-type heat exchangers. A numerical two-dimensional analysis has been conducted in a transient state using N-eicosane PCM, considering the natural convection effect. The CFD of this numerical model has been validated with pertinent literature work. The evolution of the solid-liquid interface and natural convection has been visualized by liquid fraction, isotherm expansion and velocity streamlines. At first, three proposed branching designs are compared for different numbers (two, three and four) of rectangular fins. Following the methodology, evaluating the impact of branching fins for two and four rectangular fins, the best branching design was the angled fins with 8.25 % and 28.58 % melting time improvement, respectively, compared to the curved fins, which performed the worst. For three rectangular fins, straight branching fins were identified as the best with a 21.2 % melting time improvement compared to the angled branching fins as the worst performer. Lastly, among all the nine cases, two rectangular fins with angled branching perform the best, with 84.6 % melting time savings. The worst performer is four rectangular fins with curved branching, saving 40 % melting time compared to no fin case. In addition to that, the cases with two rectangular fins significantly outperform other cases in terms of energy storage rate.

Vibrations and thermoelastic quality factors of hemispherical shells with fillets

In engineering applications, hemispherical shell resonators are typically machined with fillets to reduce stress concentration and enhance structure strength. The fillets will inevitably affect the dynamic properties and the mechanical quality factor of hemispherical shell resonators, which has been seldom investigated before. In this paper, an effective analytical method is developed to explore the free vibration and thermoelastic damping (TED) characteristics of the hemispherical shell with fillets. The fillets are characterized by the variation in the thickness of the hemispherical shell during modelling. The first-order shear deformation theory (FSDT) is used to describe the theoretical formulas of the hemispherical shell with fillets. By employing the unified Jacobi polynomials and Fourier series as the assumed mode shape functions, the equation of motion of the structure is established by Hamilton's principle and the assumed mode method. The analytical model for thermoelastic quality factor (QTED) which is determined by TED is obtained by computing the dissipated energy and the maximum elastic potential energy of the hemispherical shell with fillets. The validity and accuracy of the present method are confirmed by comparing the present solutions with the published results and those obtained from the finite element method (FEM). The influences of fillets on the vibration behaviors and QTED characteristics of the hemispherical shells are analyzed in detail. The present model can be used to optimize the design of the fillets of the hemispherical shell resonators with high quality factors.

Insulating-to-conducting state transition in the bilayer Hubbard model induced by a perpendicular quench field

A many-body quantum system with varying parameters can exhibit two distinct quantum states within the same energy shell. This allows for a dynamic transition from the ground state of the pre-quench Hamiltonian to a steady state of the post-quench Hamiltonian. We investigate the dynamic response of the ground states in a two-layer half-filled Hubbard model to a perpendicular electric field. We demonstrate that the steady state exhibits conductivity when the field is in resonance with the on-site repulsion, while the initial state is a Mott-insulating state. Additionally, the two layers exhibit identical conducting behavior due to the formation of long-lived dopings, as evidenced by the charge fluctuation. The key factor in achieving this dynamic transition is the cooperative interplay between on-site interactions and the resonant field, rather than the individual roles they play. Our findings offer an alternative mechanism for field-induced conductivity in strongly correlated systems.

Nuclear Physics in the Era of Quantum Computing and Quantum Machine Learning

AbstractIn this paper, the application of quantum simulations and quantum machine learning is explored to solve problems in low‐energy nuclear physics. The use of quantum computing to address nuclear physics problems is still in its infancy, and particularly, the application of quantum machine learning (QML) in the realm of low‐energy nuclear physics is almost nonexistent. Three specific examples are presented where the utilization of quantum computing and QML provides, or can potentially provide in the future, a computational advantage: i) determining the phase/shape in schematic nuclear models, ii) calculating the ground state energy of a nuclear shell model‐type Hamiltonian, and iii) identifying particles or determining trajectories in nuclear physics experiments.

Experimental validation of a design model for latent thermal energy storage extended with sensible heat

Latent thermal energy storage can be a key technology for a green energy transition by matching fluctuating heat demand and supply. In order to implement a storage system, it needs to be designed which requires estimating the outlet temperature of a system for a given geometry and time history of the heat transfer fluid’s mass flow rate and inlet temperature. Currently, design methods are either overly simplistic, focusing solely on e.g. the phase change time or requiring the solution of partial differential equations which can be computationally expensive. The present paper proposes a novel approach where a latent thermal energy storage system is decomposed into a heat transfer fluid vessel, a sensible storage system and a storage system with only latent heat. Computationally inexpensive models are available for all three of these sub heat exchangers. A heat exchanger model is obtained by connecting the sub heat exchangers in parallel. This novel approach is used to model an industrial scale shell and tube latent thermal energy storage heat exchanger. The predicted outlet temperature is compared to the measured outlet temperature and the design model obtains good agreement.

Resonant photoemission studies on Fe-Ni alloys

This paper investigates the electronic structure of Fe1−xNix (x = 0.32, 0.36, 0.4, 0.5) alloys employing high resolution photoelectron spectroscopy using synchrotron radiation. The valence bands and the core levels have been recorded at various on-resonance and off-resonance photon energies of Fe and Ni. An anti-resonance dip observed in the valence bands taken at Fe 3p → 3d resonance lies closer to the Fermi level compared to that observed at Ni 3p → 3d resonance, indicating larger density of itinerant Fe 3d electrons. Whereas, Ni 3d states are comparatively less itinerant in these alloys. The hybridization effects increase with increase of Fe content in the alloy system. The intensity of Ni L3M4,5M4,5 Coster-Cronig Auger transition observed with 853 eV (Ni 2p → 3d resonance) photon energy, drops down drastically for the Invar alloy (Fe0.64Ni0.36) as compared to other Fe-Ni alloys due to the existence of Ni in more than one local chemical surroundings as expected for Invar alloy. The electron-electron interaction energy (Udd) of Ni 3d shell is found to decrease with the decrease of Ni concentration. The 3p and 3s core levels of Fe and Ni recorded at 707 eV (Fe 2p → 3d resonance) are overwhelmed by various intense resonant Auger features such as Fe L3M2,3M2,3, Fe L3M2,3M4,5 and Fe L3M1M4,5. The 1S state of Fe L3M2,3M2,3 is greatly enhanced in the Invar alloy as compared to other alloys. The microscopic compositional in-homogeneity present in Invar alloy plays a crucial role in the screening of holes in Ni sites but does not contribute in screening the holes in Fe sites.

Stability of charged anisotropic thin shell gravastars admitting conformal motion in [formula omitted] gravity

This paper investigates the interesting features of gravastar configuration under charged anisotropic fluid distribution considering geometry-matter coupling theory. In the context of f(R,T) gravity, we derive exact solutions of the Einstein field equations using the linear form of the function f(R,T)=R+2γT, where R is the Ricci scalar and T is the trace of the energy–momentum tensor with conformal motion. We consider three different regions of gravastar, the interior region having a definite radius r, the intermediate layer of matter with the thickness ϵ, and the outer region with the radius r+ϵ. For the viability of our developed solution, we examine the metric potentials, energy density, and pressure components inside the thin shell for different values of theory parameter γ, and charge Q. Using the well-known matching conditions, we interpret the dynamical properties of gravastar such as surface charge density, surface pressure, proper length, equation of state parameter, entropy, and evolution of shell energy under the allowed range of parameters. Moreover, we analyze the presence of realistic matter inside the thin shell through energy conditions. The dynamical stability of the gravastar is checked through the equilibrium profile and speed of sound parameter, which shows the stable configuration of the gravastar in our theoretical studies.

Hartree-Fock Calculations of 12C Nucleus at Equilibrium and Under Static Compression

Abstract: The ground state features of the semi-doubly magic 12C nucleus (i.e. binding energy, nuclear radius, radial density distribution, and single particle energies) are estimated using ab initio calculations at equilibrium and under high static compression. Nijmegen and Reid soft-core (RSC) potentials are used as input nucleon-nucleon interactions. Within the framework of the constrained spherical Hartree-Fock approximations, we do the calculations in no-core shell-model space, which consists of six major oscillator shells (i.e. 21 single particle orbitals). The sensitivity of the ground state features of the 12C nucleus to the degree of compression and the sensitivity of the equation of state to the two potentials are investigated. We also discovered that the nuclear binding energy calculated using the Nijmegen potential is higher than that calculated using the RSC potential. When utilizing the Nijmegen potential, the curve reaches zero binding energy faster than when using the RSC potential. Besides, in the case of Nijmegen, the spectrum of single-particle energies increases more quickly than in the case of RSC potential under compression. The space between single-particle energy shells is also visible in the energy spectrum. At high compression, the radial density distribution becomes higher than that in the interior zone when the RSC potential is applied. Keywords: Nijmegen potential, RSC potential, Ab-initio calculations model, Radial density distribution, Ground state, 12C nucleus.

The rigid-flexible coupling vibration of assembled disk-composite conical shell structure of electric aircraft in hygrothermal circumstance

A novel theoretical formulation for addressing the coupling vibration of the rigid disc and flexible composite conical shell structure (RDFCCSs) in hygrothermal circumstances is established to investigate the vibration evolution of the rigid-flexible composite thin-walled coupled structure of new energy electric aircraft. According to Donnell's thin shell theory, the potential energy of the composite conical shell under hygrothermal load is calculated. A uniform mass model and a set of artificial springs distributed on the interface of the shell and disk are imported to simulate the RDFCCSs. The governing equation of the RDFCCSs with arbitrary foundations in hygrothermal circumstances is deduced according to the Rayleigh-Ritz variational procedure. Systematic experiments and finite element simulations have been demonstrated to confirm the accuracy of the proposed method. Three new rigid-flexible coupling vibration modes of the RDFCCSs that differ from the traditional single thin-walled conical shell element due to the influence of the disk have been revealed. After that, the unique vibration characteristics of RDFCCSs under various masses, axial loads, hygrothermal environments and interface connection stiffnesses are discussed in detail.