Multi-modal calculations of prompt fission neutrons from 238U（n,f） at low induced energy

Properties of prompt fission neutrons from UP>238UP>U(n, f) are calculated for incident neutron energies below 6 MeV using the multi-modal model, including the prompt fission neutron spectrum, the average prompt fission neutron multiplicity, and the prompt fission neutron multiplicity as a function of the fission fragment mass υ(A) (usually named “sawtooth” data) The three most dominant fission modes are taken into account. The model parameters are determined on the basis of experimental fission fragment data. The predicted results are in good agreement with the experimental data.     

Which finite simple groups are unit groups?

We prove that if G$G$ is a finite simple group which is the unit group of a ring, then G$G$ is isomorphic to: (a) a cyclic group of order 2; or (b) a cyclic group of prime order 2^k−1$2^k-1$ for some k$k$; or (c) a projective special linear group _PSLn(_F2)${PSL}_n\left({\mathbb{F}}_2\right)$ for some n≥3$n\ge 3$. Moreover, these groups do all occur as unit groups. We deduce this classification from a more general result, which holds for groups G$G$ with no non-trivial normal 2-subgroup.     

Computing devices,mathematics education and mathematics: Sexton’s omnimetre in its time

Material objects can tell us much about mathematical practice. In 1899, Albert Sexton, a Philadelphia mechanical engineer, received the John Scott Medal of the Franklin Institute for his invention of the omnimetre. This inexpensive circular slide rule was one of a host of computing devices that became common in the United States around 1900. It is inscribed “NUMERI MUNDUM REGUNT”. In part because of instruments such as the omnimetre, numbers increasingly ruled the practical world of the late 19th and early 20th century. This changed not only engineering, but mathematics education and mathematical work.     

网络境遇下中美青少年德育比较研究

美国作为互联网的诞生地,其青少年网络道德教育体系正趋于完善,值得我们借鉴学习。我们应从强化学校教育、加强家庭教育、完善法制教育等方面着手,不断发展我国青少年的道德教育模式,以适应网络技术发展的需求。     

《培尔·金特》的圣经U型结构解析

《培尔·金特》是19世纪挪威杰出剧作家易卜生的关于罪恶与救赎、爱与信念的长篇诗剧。细读文本,不难发现培尔的赎罪之路,遵循了圣经的"犯罪受难忏悔获救"的情节模式,呈现出人生命运先下降后上升的"U"型曲线。易卜生在这部戏剧中将笔触深入培尔的灵魂深处,展现他一生之中一步步对自我进行宗教救赎的历程。     

随机向量中的分量负相依变点问题的统计推断

论文讨论了独立随机向量序列X