分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: This paper presents entropy symmetrization and high-order accurate entropy stable schemes for the relativistic magnetohydrodynamic (RMHD) equations. It is shown that the conservative RMHD equations are not symmetrizable and do not admit a thermodynamic entropy pair. To address this issue, a symmetrizable RMHD system, equipped with a convex thermodynamic entropy pair, is proposed by adding a source term into the equations, providing an analogue to the non-relativistic Godunov--Powell system. Arbitrarily high-order accurate entropy stable finite difference schemes are developed on Cartesian meshes based on the symmetrizable RMHD system. The crucial ingredients of these schemes include (i) affordable explicit entropy conservative fluxes which are technically derived through carefully selected parameter variables, (ii) a special high-order discretization of the source term in the symmetrizable RMHD system, and (iii) suitable high-order dissipative operators based on essentially non-oscillatory reconstruction to ensure the entropy stability. Several numerical tests demonstrate the accuracy and robustness of the proposed entropy stable schemes.
分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: In this study, strains of Aspergillus niger 4# for hyper citric acid were irradiated to different doses by 80 MeV/u 12C6+ ion beams. Seven mutant strains showed marked citric acid over-production records and faster productivity than initial Aspergillus niger 4# by shaking flash fermentation. The maximum product yield was 132.8 -g L-1( the H4002 strain) being a 8.8% increase to the initial strain. The scale-up experiment was carried out in a 100 L bioreactor. The mutant H4002 can accumulate 187 -g L-1 product yield of citric acid from starch liquefying supernatant. The productivity of citric acid was 2.75 g L-1 h-1. So, the mutant H4002 possesses rapid sugar katabolism for producing citric acid. Meanwhile, the pellet morphology kept compact and round during the whole submerged fermentation, which was suited to produce citric acid. The results indicate that mutant H4002 has potential ability to produce citric acid rapidly.
分类: 核科学技术 >> 粒子加速器 提交时间: 2021-12-31
摘要: Collinear laser spectroscopy is a powerful tool for studying the nuclear spins, electromagnetic moments, and charge radii of exotic nuclei. To study the nuclear properties of unstable nuclei at the Beijing Radioactive Ion#2;beam Facility (BRIF) and the future High Intensity Heavy-ion Accelerator Facility (HIAF), we developed a collinear laser spectroscopy apparatus integrated with an offline laser ablation ion source and a laser system. The overall performance of this state-of-the-art technique was evaluated and the system was commissioned using a bunched stable ion beam. The high-resolution optical spectra for the 4s 2S1/2 → 4p 2P3/2 (D2) ionic transition of 40,42,44,48Ca isotopes were successfully measured. The extracted isotope shifts relative to 40Ca showed excellent agreement with the literature values. This system is now ready for use at radioactive ion beam facilities such as the BRIF and paves the way for the further development of higher-sensitivity collinear resonant ionization spectroscopy techniques.