AAPPS Bulletin最新文献

This study focuses on developing a mathematical model to compute geographic coordinates (GCS) for any point on Earth based on the horizontal coordinates of observable celestial bodies with known motion at a specific time, such as the Sun, Moon, planets, and stars. Also, the model is applicable during daylight hours, as it can be implemented using sunlight shadows. Additionally, the position of a celestial body at a given time enables precise determination of geographic directions, such as true north. This facilitates accurate alignment of buildings intended for specific orientations, including scientific facilities, temples, and residential buildings designed to harmonize with wind patterns and sunlight exposure. This method is cost-effective, as it does not rely on Global Navigation Satellite System (GNSS) like GPS, BDS, GALILEO, and GLONASS. In addition, a prototype device was engineered to instantaneously determine the Sun’s horizontal coordinates using photovoltaic cells.

We employ cluster extension of dynamical mean-field theory (CDMFT) to systematically investigate the impact of double counting corrections on the correlated electronic structure of La₃Ni₂O₇ under ambient pressure. By adjusting double-counting parameters, while maintaining a fixed Fermi surface, we observe a pronounced orbital-selective density of states change: the (d_{z^2}) orbital undergoes significant variation near the Fermi level with increasing (E_{dc}^z), while the (d_{x^2-y^2}) orbital remains essentially unchanged throughout the entire range. Analysis of renormalization factor show the monotonic dependence with double counting in both (d_{z^2}) and (d_{x^2-y^2}) orbital, and it also identifies an optimal double counting window in (d_{z^2}) orbital aligns with experimental values. We also find the interlayer Matsubara self energy exhibits non-monotonic dependence on (E_{dc}^z), deviating from theoretical predictions. This anomaly is attributed to the metallization of oxygen-bridged pathways, which disrupts the prerequisite for charge transfer via apical oxygen. Our results establish (E_{dc}) as a critical control parameter for correlated electronic structure in La₃Ni₂O₇ and provide a computational framework for resolving orbital-dependent correlation effects in layered materials.

We predict the existence of two tri-critical quantum Lifshitz points in recently discovered d-wave altermagnetic metals subjected to an external magnetic field. These points connect a spatially modulated Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) phase, a uniform polarized Bardeen–Cooper–Schrieffer (BCS) superconducting phase, and the normal metallic phase in a nontrivial manner. Depending on whether the FFLO state is primarily induced by the magnetic field or by d-wave altermagnetism, we classify the corresponding Lifshitz points as field-driven or altermagnetism-driven, respectively. Notably, the two types exhibit distinct behaviors: the transition from the FFLO phase to the polarized BCS phase is first-order near the field-driven Lifshitz point, as might be expected, whereas it becomes continuous near the altermagnetism-driven Lifshitz point. We further explore the effects of finite temperature and find that the altermagnetism-driven Lifshitz point is significantly more sensitive to thermal fluctuations.

We review field-theoretic studies of charge transport in hot relativistic plasmas under strong magnetic fields and extend the analysis to thermal conductivity. The calculations rely on accurately determining the fermion damping rate. Using the Landau-level representation, these damping rates are computed exactly at leading order and incorporated into the Kubo formula to obtain the thermal and electrical conductivity tensors. Our analysis reveals that the mechanisms underlying longitudinal and transverse transport differ significantly. Strong magnetic fields markedly suppress transverse charge transport by confining particles within localized Landau orbits, allowing transport only through quantum transitions between these discrete states. In contrast, longitudinal charge transport is enhanced, as it primarily depends on the reduced scattering probability of particles moving along the direction of the magnetic field. The anisotropy of thermal conductivity is also non-trivial but less pronounced since its underlying transport mechanism is different. We also examine the modification of the Wiedemann–Franz law in strongly magnetized plasmas.

A proton beam is produced at a velocity of the order of ({10}^{9} cm/s) to interact with an uncharged hydrogen-boron medium such as ({H}_{3}B). The generated charged particles are confined by electromagnetic fields. This is the basic concept of the new non-thermal fusion reactor. An external electric field is applied to prevent the energy loss of the proton particles by friction, due to their interaction with the electrons of the medium, to keep the proton-boron fusion at a maximum cross-section. Alphas produced by (p{B}^{11}) fusion undergo nuclear elastic collisions with surrounding protons, triggering a (p{B}^{11}) CR. The aim of this paper is to estimate the key parameters related to the performance of a new fusion reactor with neutron-free fusion fuel (p{B}^{11}) considering the production of alpha particle avalanches by presenting only the main physical processes and not a complete engineering design. To achieve this goal, a conceptual fusion reactor is proposed in this work using laser-plasma interactions and magnetic confinement configurations. The final result of our work considering this new reactor shows that it is possible to achieve fusion energy gain about 115, which is much higher than other cases examined.

Indirect-drive double-shell implosions have been performed at 100 kJ laser facility in China. The system of differential equations for the unablated mass, the average implosion velocity, and the ablation front radius of an outer shell within an indirect-drive double-shell capsule during acceleraction and deceleraction phases has been proposed from conservation principles of hydrodynamics. In addition, corrected rocket model for the inner shell has been built; the radius and velocity of the outer surface of the inner shell, as well as the radius and velocity of the inner shell mass center, are solved and give simple expressions. These relations provide the maximum implosion velocity and remaining unablated mass in terms of the initial capsule and the radiation temperature. These results are compared with numerical simulations, and good agreements have been observed.

Multiferroic materials, particularly rare-earth orthochromates (RECrO(_3)), have garnered significant interest due to their unique magnetic and electric-polar properties, making them promising candidates for multifunctional devices. Although extensive research has been conducted on their antiferromagnetic (AFM) transition temperature (N(acute{mathrm{e}})el temperature, (T_mathrm{N})), ferroelectricity, and piezoelectricity, the effects of doping and substitution of rare-earth (RE) elements on these properties remain insufficiently explored. In this study, convolutional neural networks (CNNs) were employed to predict and analyze the physical properties of RECrO(_3) compounds under various doping scenarios. Experimental and literature data were integrated to train machine learning models, enabling accurate predictions of (T_mathrm{N}), besides remanent polarization ((P_mathrm{r})) and piezoelectric coefficients ((d_{33})). The results indicate that doping with specific RE elements significantly impacts (T_mathrm{N}), with optimal doping levels identified for enhanced performance. Furthermore, high-entropy RECrO(_3) compounds were systematically analyzed, demonstrating how the inclusion of multiple RE elements influences magnetic properties. This work establishes a robust framework for predicting and optimizing the properties of RECrO(_3) materials, offering valuable insights into their potential applications in energy storage and sensor technologies.

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