激光陀螺稳频稳锁区控制系统参数模型研究

采用DSP技术设计了激光陀螺稳频稳锁区控制系统,利用转台、温度箱等设备开发了稳频稳锁区控制参数测试系统.结合某型激光陀螺,对控制系统的压电陶瓷特性、光强和锁区特性进行了全面测试,对激光陀螺工作模态选定和锁区稳定范围进行了研究,建立了有针对性的稳频稳锁区控制系统参数模型.最后,对利用该参数模型的某型陀螺在常温下进行了验证试验.陀螺工作正常,无跳模现象,其零偏重复性小于0.01 °/h,表明所建参数能有效控制陀螺.     

电偶极子模型及其应用

讨论和研究了电偶极子模型在电解质的极化、电磁波的辐射以及人体生物电活动中的应用.     

基于随机过程理论短螺旋钻头载荷的数学模型

为了揭示短螺旋钻头载荷随切削厚度和岩石接触强度变化规律,根据岩石的物理力学特性,结合单个镐型截齿切削破岩的工作机理和短螺旋钻头的结构特征,分析短螺旋钻头入岩工况下的受载情况;运用随机过程理论,建立短螺旋钻头随机载荷的数学模型.针对不同的岩石接触强度和钻头切削深度,借助MATLAB仿真求解钻头的扭矩和轴向力,采用数学统计方法对实测结果进行处理分析,并与理论值相比较.研究结果表明:理论求解的钻头扭矩和轴向力的幅值与均值和实际测试值都比较接近,且两者的变化规律一致;在切削厚度一定时,扭矩和轴向力的幅值和均值随着岩石接触强度的增大而迅速增大;在岩石接触强度一定时,扭矩和轴向力的幅值和均值也会随着切削厚度的增大而迅速增大.     

Quiet debut for the double helix

Past discoveries usually become aggrandized in retrospect, especially at jubilee celebrations, and the double helix is no exception. The historical record reveals a muted response by the scientific community to the proposal of this structure in 1953. Indeed, it was only when the outlines appeared of a mechanism for DNA's involvement in protein synthesis that the biochemical community began to take a serious interest in the structure.     

庇护效应对一类生态-流行病模型稳定性的影响

研究了一类捕食系统中食饵具有流行病和庇护所效应的生态-流行病模型．假设捕食者为HollingⅡ类功能反应,食饵按常数比例庇护,建立模型．通过数学分析和数值模拟,发现庇护效应可以阻止极限环振荡的发生,增加系统的稳定性．     

Automatic removal of eye movement artifacts from the EEG using ICA and the dipole model

In this study, we proposed and evaluated the use of Independent Component Analysis (ICA) combining the EEG dipole model to automatically remove eye movement artifacts from the EEG without needing EOG as a reference. We separated the EEG data into independent components using the ICA method, and determined the source localization of these independent components with a single dipole model. The EEG signal was reconstructed by automatically excluding those components localized within a preset eye model. EEGs from 12 patients were analyzed. The experimental results indicate that ICA with the dipole model is very efficient at automatically subtracting the eye movement artifacts, while retaining the EEG slow waves and making their interpretation easier.     

An incipient 3(10) helix in Piv-Pro-Pro-Ala-NHMe as a model for peptide folding

The molecular mechanism of helix nucleation in peptides and proteins is not yet understood and the question of whether sharp turns in the polypeptide backbone serve as nuclei for protein folding has evoked controversy. A recent study of the conformation of a tetrapeptide containing the stereochemically constrained residue alpha-aminoisobutyric acid, both in solution and the solid state, yielded a structure consisting of two consecutive beta-turns, leading to an incipient 3(10) helical conformation. :This led us to speculate that specific tri- and tetrapeptide sequences may indeed provide a helical twist to the amino-terminal segment of helical regions in proteins and provide a nucleation site for further propagation. The transformation from a 3(10) helical structure to an alpha-helix should be facile and requires only small changes in the phi and psi conformational angles and a rearrangement of the hydrogen bonding pattern. If such a mechanism is involved then it should be possible to isolate an incipient 3(10) helical conformation in a tripeptide amide or tetrapeptide sequence, based purely on the driving force derived from short-range interactions. We have synthesised and studied the model peptide pivaloyl-Pro-Pro-Ala-NHMe (compound I) and provide here spectroscopic evidence for a 3(10) helical conformation in compound I.     

Controlling the double helix

Chromatin is the complex of DNA and proteins in which the genetic material is packaged inside the cells of organisms with nuclei. Chromatin structure is dynamic and exerts profound control over gene expression and other fundamental cellular processes. Changes in its structure can be inherited by the next generation, independent of the DNA sequence itself.     

瞬态N-S方程的二阶全离散稳定化两重网格有限元方法

文中对瞬态N-S方程建立了一个二阶全离散稳定化两重网格有限元方法.该方法不需要有限元空间满足inf-sup条件,格式中的稳定项也与参数选取无关且无边界积分项.在实际计算时只需先在网格长度为H的粗格上解非线性N-S方程,然后在网格长度为hH的细格上解一个线性Stokes方程,仍可达到细网格上求N-S方程的逼近精度,既节约了计算内存,也提高了计算效率.如果选择适当的网格长度,则两层格式所得到的误差与标准格式的误差具有相同的精度.     

等效电流偶极子(ECD)模型对MCG场源定位的影响

等效电流偶极子 (ECD)模型具有简要明确性 ,已经在MCG的逆问题中 ,如确定WPW综合症 ,心脏异常搏动根源、心律失常等方面 ,得到广泛应用。在多通道的体表电势图 (BSPM)的测量中也应用ECD。本文介绍用ECD的定位方法 ,由临床研究的模拟仿真描述ECD获得的结果 ,并讨论体导体模型的影响。     

科技创新三螺旋模式中政府的适切功能与定位

三螺旋理论被学界认为是科技创新研究的新领域、新模式.其一经提出受到了西方发达国家得到广泛关注并得到了深入研究及应用.我国从21世纪初开始有学者引进三螺旋的概念及理论,此后不断有新的研究成果问世.然而相关研究略显分散,且与国内科技创新实际紧密结合的研究和实践还比较滞后.科技创新三螺旋模式中大学—产业政府三者是相互独立,且...