Analysis of detection limit to time-resolved coherent anti-Stokes Raman scattering nanoscopy

In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit （DL） to time-resolved CARS （T-CARS） nanoscopy based on our proposed additional probe-beam-induced phonon depletion （APIPD） method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise （SNR） and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ~ 109 W/cm2. When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume （40-nm suppressed focal scale in APIPD method）, the DL correspondingly varies with exposure time, for example, DL values are 103 and 102 when exposure times are 20 ms and 200 ms respectively.     

The Blood Flow at Arterial Bifurcations Simulated by the Lattice Boltzmann Method

The Programmed model of non-Newtonian blood fiow （the Casson model） at arterial bifurcations is established by the lattice Boltzmann method. The blood flow field under different Reynolds numbers is simulated, and distri- bution of dynamic factors such as flow velocity, shear stress, pressure and shear rate are presented. The existence of the fluid separation zone is analyzed. This provides a basis for further studies of the relationship between hemodynamic factors and pathogenesis, as well as a reference for a better understanding of the pathological changes and location of sediments, and the plague factor in arteries.     

高精度虹膜识别光学镜头的研制

针对虹膜识别系统中难于获取高分辨率的虹膜图像问题,设计一款高精度虹膜图像采集摄像镜头。镜头焦距14.2 mm, 畸变小于0.15%,像方数值孔径为0.26,像面直径为5.35 mm,工作距离130 mm,物像共轭距为150 mm。光学系统可获得高分辨率图像,在0.7视场光学传递函数MTF在120 lp/mm时大于30%。镜头由4片球面透镜构成,结构简单,适合产业化生产,各项光学指标检测结果达到设计要求。     

快反系统中平面反射镜的轻量化设计

根据快速控制反射镜系统(快反系统)对平面反射镜的设计要求,对快反镜的轻量化结构进行了优化设计。选择比刚度大、热变形系数小的碳化硅为镜坯材料,采用背部开槽式结构减重,背部3点式支撑,对不同筋宽和镜面厚度等多种轻量化方案进行了有限元分析。结果表明:筋宽越大,镜体刚度越好,但筋宽增大到一定程度时,反射镜刚度的改善程度减缓;镜面越厚,镜体内应力、自重变形越大。结合反射镜设计要求和有限元分析结果,加工制备了筋宽为4 mm,镜面厚度为4 mm的碳化硅反射镜,镜体轻量化率达55%。实测反射镜的面形精度,其RMS值不超过λ/30,与分析结果相符,满足系统的使用要求。     

Interaction of intense laser pulses with hydrogen atomic clusters

The interaction between intense femtosecond laser pulses and hydrogen atomic clusters is studied by a simplified Coulomb explosion model. The dependences of average proton kinetic energy on cluster size, pulse duration, laser intensity and wavelength are studied respectively. The calculated results indicate that the irradiation of a femtosecond laser of longer wavelength on hydrogen atomic clusters may be a simple, economical way to produce highly kinetic hydrogen ions. The phenomenon suggests that the irradiation of femtosecond laser of longer wavelength on deuterium atomic clusters may be easier than that of shorter wavelength to drive nuclear fusion reactions. The product of the laser intensity and the squared laser wavelength needed to make proton energy saturated as a function of the squared cluster radius is also investigated. The proton energy distribution calculated is also shown and compared with the experimental data. Our results are in agreement with the experimental results fairly well.     

便携式指纹考勤信息管理系统设计

指纹识别技术是近年来应用最广泛的一种生物识别应用技术。结合该技术与当前高等教育的改革热点,本文设计了一个基于指纹识别的便携式信息管理系统。使教学互动环节不仅涵盖了基本的教师与学生的通知公告,而且涵盖了深层次的教师与学生及其家长的相互沟通、分析课程学习的优缺点、有针对性的提出各课程学习的良好建议等。系统硬件采用ARM M3处理器、指纹采集传感器、2.8寸液晶屏以及GPRS模块等,系统软件采用UCOSII操作系统。实现了课堂教学的实时考勤,统计班年级课程的平时、期中小考及期末终考成绩,分析学生的学习表现,并对师生提出教学、学习及提高教学质量的良好建议。本设计对其它考勤应用及教育领域具有一定的参考价值。     

Chirality-asymmetry force between ɑ-quartz and copper block

The chirality-asymmetry macroscopic force mediated by light pseudoscalar particles between α -quartz and some achiral matter is studied. If this force between achiral source mass and α -quartz with some chirality is attractive, it will become repulsive when the chirality of the α -quartz crystal is changed. According to the tested limits of the coupling constant g_s g_p /\hbar c< 1.5× 10^-24 at the Compton wavelength λ = 10^-3 m, the force (F) between a 0.08× 0.08× 0.002 m³ block of α -quartz and a 0.08× 0.08× 0.01 m³ copper block with a separation being 0.5× 10^-3 \mbox{m} in between, is estimated from the published data at less than 4.64× 10^-24 N, i.e. F < 4.64× 10^-24 N.     

Analysis of Hysteretic Strongly Nonlinearity for Quad Iced Bundle Conductors

A new hysteretic nonlinear model of quad iced bundle conductors is constructed. The bifurcation equation is obtained by applying the undetermined fundamental frequency method of the complex normal form. The transition set and bifurcation diagrams for the singularity are presented. Then the corresponding relations between the unfolding parameters and the system parameters are given, and the sensitivity parameters and its range of values are obtained to analyze and to control the galloping of the quad iced bundle conductor.     

扭曲光束的产生及表征

对于光斑主轴在传输过程中不停变化的扭曲光束,采用光斑主轴方向上的光束传输比对光束质量等特性进行表征和描述并不全面。针对扭曲高斯光束,在光束传输矩阵的理论计算的基础上,研究了通过双柱透镜产生扭曲光束的方法;推导得到了光束在交叉方向上光束传输比的表达式,并定义了一个新的物理量-光束的扭曲系数;分别采用光束传输矩阵和数值模拟,得到了不同柱透镜之间夹角和间距下的扭曲系数,通过光束传输比和扭曲系数共同对扭曲光束进行表征。结果表明,相比于单纯的光束传输比,两者的组合能够更好地对扭曲光束进行表征。通过实验对理论和仿真结果进行了验证,理论结果和实验结果相符。     

散裂中子源漂移管直线加速器功率耦合器的冷测及分析(英)

功率耦合器是中国散裂中子源(CSNS)漂移管直线段(DTL)的关键部件之一,其耦合系数通常通过调节耦合孔尺寸得到,为了确保耦合系数达到设计值,制造了一个冷模进行耦合度的调节。在冷模测量过程中,发现了仅通过改变耦合孔尺寸耦合系数达不到目标值的问题,因此提出了一种与测量结果对比有良好仿真精度的新模型用于分析,并使用该仿真模型分析了PEFP使用的理论及影响耦合度的主要参数。最终耦合度被调节至目标值,正式件的冷测结果也表明其与仿真结果基本相同。