A three-point fifth-order accurate generalized compact scheme (GC scheme) with a spectral-like resolution is constructed in a general way. The scheme satisfies the principle of stability and the principle about suppre...A three-point fifth-order accurate generalized compact scheme (GC scheme) with a spectral-like resolution is constructed in a general way. The scheme satisfies the principle of stability and the principle about suppression of the oscillations, therefore numerical errors can decay automatically and no spurious oscillations are generated around shocks. The third-order TVD type Runge-Kutta method is employed for the time integration, thus making the GC scheme best suited for unsteady problems. Numerical results show that the GC scheme is shock-capturing. The time-dependent boundary conditions proposed by Thompson are well employed when the algorithm is applied to the Euler equations of gas dynamics.展开更多
A generalized Einstein relation is established for a drifted Brownian motion on a compact orientable Remannian manifole. The original form of such relation comes from an explicit formula of diffusion coeffcient by usi...A generalized Einstein relation is established for a drifted Brownian motion on a compact orientable Remannian manifole. The original form of such relation comes from an explicit formula of diffusion coeffcient by using the autocorrelation function of the velocity of the Einstein fluctuation theory of the diffusion process展开更多
A reliable ^(235)U enrichment uniformity detection system based on a compact D–D neutron generator is developed to detect the ^(235)U enrichment uniformity of different fuel elements in the same nuclear fuel rod. The...A reliable ^(235)U enrichment uniformity detection system based on a compact D–D neutron generator is developed to detect the ^(235)U enrichment uniformity of different fuel elements in the same nuclear fuel rod. The high-yield compact D–D neutron generator provides 2.45 MeV D–D neutrons, decelerated by a moderator to thermal neutrons or epithermal neutrons, thereby inducing ^(235)U fission to produce highly excited state fission fragments that undergo de-excitation via γ-ray emission. The system detects the ^(235)U enrichment uniformity of a nuclear fuel rod by measuring γ-rays and establishing a relationship between the γ-ray count rate and ^(235)U enrichment in nuclear fuel. The proposed system yields a confidence probability of 99.99% for a relative ^(235)U enrichment deviation of 10% and a neutron yield of 5 × 10^(8) n/s, and the detection accuracy increases with increasing neutron yield. Furthermore, the developed system can satisfy quality control requirements for nuclear fuel production to promote the safe development of nuclear power.展开更多
基金The project supported by the National Natural Science Foundation of China (19972038)Foundation of the National CFD Laboratory of China
文摘A three-point fifth-order accurate generalized compact scheme (GC scheme) with a spectral-like resolution is constructed in a general way. The scheme satisfies the principle of stability and the principle about suppression of the oscillations, therefore numerical errors can decay automatically and no spurious oscillations are generated around shocks. The third-order TVD type Runge-Kutta method is employed for the time integration, thus making the GC scheme best suited for unsteady problems. Numerical results show that the GC scheme is shock-capturing. The time-dependent boundary conditions proposed by Thompson are well employed when the algorithm is applied to the Euler equations of gas dynamics.
文摘A generalized Einstein relation is established for a drifted Brownian motion on a compact orientable Remannian manifole. The original form of such relation comes from an explicit formula of diffusion coeffcient by using the autocorrelation function of the velocity of the Einstein fluctuation theory of the diffusion process
基金This work was supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.12075105,11705071 and 11875155)the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics(Grant No.U1830102)+1 种基金the NSFC-Nuclear Technology Innovation Joint Fund(Grant No.U1867213)the Fundamental Research Funds for the Central Universities(Grant No.lzujbky-2021-kb09)。
文摘A reliable ^(235)U enrichment uniformity detection system based on a compact D–D neutron generator is developed to detect the ^(235)U enrichment uniformity of different fuel elements in the same nuclear fuel rod. The high-yield compact D–D neutron generator provides 2.45 MeV D–D neutrons, decelerated by a moderator to thermal neutrons or epithermal neutrons, thereby inducing ^(235)U fission to produce highly excited state fission fragments that undergo de-excitation via γ-ray emission. The system detects the ^(235)U enrichment uniformity of a nuclear fuel rod by measuring γ-rays and establishing a relationship between the γ-ray count rate and ^(235)U enrichment in nuclear fuel. The proposed system yields a confidence probability of 99.99% for a relative ^(235)U enrichment deviation of 10% and a neutron yield of 5 × 10^(8) n/s, and the detection accuracy increases with increasing neutron yield. Furthermore, the developed system can satisfy quality control requirements for nuclear fuel production to promote the safe development of nuclear power.
