数字示波器实验内容的一个有趣拓展

在数字示波器实验中,我们引入一个利用压电陶瓷片观测实验者脉搏信号的实验内容。通过此实验,学生不仅能够进一步熟练数字示波器的相关使用功能,而且能够切身感受相关实验的测量方法,极大提高了学生的实验兴趣。     

Confined subdiffusion in three dimensions

Three-dimensional （3D） Fick＇s diffusion equation and fractional diffusion equation are solved for different reflecting boundaries. We use the continuous time random walk model （CTRW） to investigate the time-averaged mean square dis- placement （MSD） of a 3D single particle trajectory. Theoretical results show that the ensemble average of the time-averaged MSD can be expressed analytically by a Mittag-Leffler function. Our new expression is in agreement with previous formu- las in two limiting cases： （^-δ2） ~ △1 in short lag time and （^-δ2} ~ △1 -α in long lag time. We also simulate the experimental data of mRNA diffusion in living E. coli using a 3D CTRW model under confined and crowded conditions. The simulation results are well consistent with experimental results. The calculations of power spectral density （PSD） further indicate the subdiffsive behavior of an individual trajectory.     

序言

<正>近40年来,几何设计与计算这一数学、计算机科学与机械制造的交叉学科得到迅速发展,以此为重要基础产生的计算机辅助设计技术使得航空、船舶和汽车等制造领域的设计过程发生了革命性变革.近年来,三维数字几何继图像、声音和视频之后,成为几何设计与计算学科的前沿课题,并有望成为下一代新型数字媒体的重要理论支撑.     

告作者

<正>为适应我国信息化建设需要,实现科技期刊编辑、出版、发行工作的电子化,推进科技信息交流网络化的进程,扩大作者学术交流渠道,本刊已加入《中国学术期刊(光盘版)》和"中国期刊网"。并入网"万方数据——数字化期刊群"和"书生数字期刊"。作者著作权使用费与本刊稿酬一次性给付。如作者不同意将文章编入该数据库,请在来稿时声明,本刊将作适当处理。本刊所载论文经"学术不端文献检测系统"检测,凡属"疑似学术不端文献"[由"中国     

A class of stochastic differential equations with the time average

Stochastic diferential equations with the time average have received increasing attentions in recent years since they can ofer better explanations for some fnancial models.Since the time average is involved in this class of stochastic diferential equations,in this paper,the linear growth condition and the Lipschitz condition are diferent from the classical conditions.Under the special linear growth condition and the special Lipschitz condition,this paper establishes the existence and uniqueness of the solution.By using the Lyapunov function,this paper also establishes the existence and uniqueness under the local Lipschitz condition and gives the p-th moment estimate.Finally,a scalar example is given to illustrate the applications of our results.     

PAMAM树枝形分子与KALP肽相互作用的计算机模拟研究

采用粗粒化的分子动力学模拟研究了跨膜多肽,lysine-flanked peptide(KALP),对第四代聚酰胺-胺(PAMAM)树枝形分子形态结构的影响.考虑了中性和酸性两种不同pH环境下两个分子间的相互作用行为.计算了PAMAM分子的回转半径、非球形因子、相对于树枝形分子质心的径向密度分布函数,和两分子间的平均力势.模拟发现在两种pH环境下KALP多肽对树枝形分子的大小、形状及密度分布影响不大,证实了PAMAM树枝形分子内部有一定空间容纳KALP多肽分子.自由能的计算结果表明酸性pH环境中PAMAM分子排斥KALP肽,无法形成复合结构;在中性pH环境中,两种分子也不容易形成稳定的复合结构.