A New Optical Imager for Hemoglobin Distribution in Human Skin

A new four-wavelength optical imager has been developed for the evaluation of various vascular diseases. Four-wavelength optical intensity images are transformed to an oxygenation mapping, which further provide maps of rapid changes in hemoglobin distribution in human skin related with peripheral blood flow. This paper presents the configuration of the system and test measurements for foot disease. Forty-nine volunteers took part in our measurements with an occlusion test of their legs. Some differences were observed in oxygenation change between healthy volunteers and patients, and arteriosclerosis obliterate (ASO) patients and healthy volunteers were clearly distinguishable.     

Estimation of Absorbing Components in a Local Layer Embedded in the Turbid Media on the Basis of Visible to Near- Infrared (VIS-NIR) Reflectance Spectra

A new method is studied for estimating the hemoglobin concentration and oxygenation of a local blood layer in a human skin tissue model on the basis of visible and near infrared reflectance spectra. This method uses the iterative Monte Carlo technique for a multi-layered skin tissue model. The numerical simulation was performed to investigate the effects of estimation errors for epidermis and dermis layers on the results for the local blood layer. Experiments with skin tissue phantoms were performed to verify the possibility of this method.     

植物研究用γ射线成像系统设计（英文）

为了利用正电子发射断层成像技术在植物生理功能研究中的优势,正在开发由两个探测器相向放置构成的γ射线成像系统.系统中采用的探测器是由10×10的氧正硅酸镥(LSO)晶体阵列与滨松R5900-C12耦合组成.单个LSO尺寸为1.8mm×1.8mm×10mm.根据PET应的特点,测试了该探测器的性能.所有闪烁晶体的图像在位置图谱中清楚可见;511keV全能峰处的能量分辨率位于14.5%-22%之间;符合时间分辨率随着位置灵敏光电倍增管的供给电压的增加而得到改善.这些实验结果表明,该LSO探测器适于构造高分辨率的双探测器成像系统.     

椭偏光学显微成像系统聚焦评价函数的研究

自动聚焦技术在椭偏光学显微成像系统中是一项关键的技术。利用几种常用聚焦评价函数作为研究手段研究了这一过程。实验中采用硅基底表面人血纤维蛋白膜层和多元蛋白质芯片样品作为研究对象,研究了几种函数在自动聚焦过程中函数值的变化,以及噪音、样品区域选择对聚焦效果的影响。实验验证托普拉斯评价函数和Sobel评价函数可以满足系统的要求;采用多幅图像平均的方法可以有效降低噪音．当平均次数达到9次以上．系统噪音的影响就可以被降至有效评价的程度;沿同一锐边,选择不同的调焦区域．对聚焦过程基本没有影响;利用评价函数在实验中确定了倾斜平面成像的最佳聚焦平面,并与理论像平面吻合。实验证明利用聚焦评价函数可以成功实现自动聚焦技术在椭偏光学显微成像系统中的应用。     

用于复色哈特曼人眼波像差测量的折/衍混合调焦系统

设计了一个折/衍混合多色调焦系统,可用于哈特曼波前传感器测量不同波长下人眼的波像差.系统由两片折射透镜和一个二元衍射面构成,焦距调整范围为－200～200 mm.系统性能达到衍射受限,在0.488～0.655 μm波长范围内,焦点色位移小于3 μm.整个系统结构简单、紧凑,同哈特曼波前传感器相匹配,可用于普通人群眼波像差的测量.     

水平场景无畸变折反射全景成像系统透镜畸变的消除

采用短焦距透镜设计水平场景无畸变折反射全景成像系统,会使系统更加小型化,然而短焦距透镜的畸变会对系统成像产生影响。为此建立了具有径向畸变的相机模型;根据这一相机模型,研究了采用短焦距摄像头的水平场景无畸变折反射全景成像系统中,透镜畸变对系统成像的影响,结果表明短焦距透镜的畸变会对系统成像产生严重影响;为了消除透镜畸变的影响,对反射镜的设计进行了改进,在反射镜面形微分方程中包含了透镜畸变消除的参量;按新的方法,设计了一套由短焦距摄像头组成的水平场景无畸变折反射全景成像系统。     

统一坐标系下多介质流体力学计算的一种方法

采用一种基于网格节点之间的吸引和排斥重新分布节点的移动网格目的确定网格移动的速度,目的简单,易于实现.数值结果表明,本目的不仅可以显著地提高计算效率,而且仍然具有较高的流场分辨率.     

Berry Phases for the L—S Coupled System in a Time—Dependent Magnetic Field

By the unitary transformation method,the instantaneous energy eigenstates of the L-S coupled system in a time-dependent magnetic field,hence the Berry phases,are calculated.     

Energy and Exergy Analysis of an Absorption and Mechanical System for a Dehumidification Unit in a Gelatin Factory

In this paper, an energy and exergy analysis is applied to the air dehumidification unit of a liquid desiccant system in an industrial gelatin conveyor dryer. The working fluid is a binary solution of lithium chloride (LiCl) in water. Dry air is used in order to decrease the amount of liquid in the gelatin. Therefore, the environmental air must have its absolute humidity reduced from about 12 g/kg to the project target, which is 5 g/kg. The process is a cycle using an absorption desiccant unit (LiCl in water), where the weak solution absorbs water vapor from the air. In the regenerator, condensation of the solution (desorption) from the moist air occurs. As a result, the steam consumption of the desorber and electrical power used for the vapor compression chiller (with ammonia, NH3, as working fluid) are the primary sources of cost for the factory. To improve the plant’s energy and exergy behaviors, the process is evaluated using a mathematical model of the system processes. In addition, we evaluate the substitution of the vapor compression chiller by an absorption unit (lithium bromide (LiBr) in water). The performance indicators of the compression vapor systems showed the best results. Even when using the condenser’s energy to pre-heat the solution, the installed system proved to be more effective.     

Application of a Gas-Kinetic BGK Scheme in Thermal Protection System Analysis for Hypersonic Vehicles

One major problem in the development of hypersonic vehicles is severe aerodynamic heating; thus, the implementation of a thermal protection system is required. A numerical investigation on the reduction of aerodynamic heating using different thermal protection systems is conducted using a novel gas-kinetic BGK scheme. This method adopts a different solution strategy from the conventional computational fluid dynamics technique, and has shown a lot of benefits in the simulation of hypersonic flows. To be specific, it is established based on solving the Boltzmann equation, and the obtained gas distribution function is used to reconstruct the macroscopic solution of the flow field. Within the finite volume framework, the present BGK scheme is specially designed for the evaluation of numerical fluxes across the cell interface. Two typical thermal protection systems are investigated by using spikes and opposing jets, separately. Both their effectiveness and mechanisms to protect the body surface from heating are analyzed. The predicted distributions of pressure and heat flux, and the unique flow characteristics brought by spikes of different shapes or opposing jets of different total pressure ratios all verify the reliability and accuracy of the BGK scheme in the thermal protection system analysis.     

阵列波导光栅解调系统光电集成中Si纳米线AWG的设计

设计了一种阵列波导光栅解调集成系统中的8通道Si纳米线阵列波导光栅波分复用器。根据材料的折射率设计了单模波导截面尺寸,利用光束传播法对所设计阵列波导光栅进行了模拟。结果表明,器件尺寸为200μm×219μm,远小于目前技术较成熟的硅基SiO2的尺寸,光功率分布符合高斯分布,信道间隔为1.8nm,串扰小于-21dB。对小尺寸AWG的设计具有参考意义。     

Painleve Analysis and Darboux Transformation for a Variable-Coefficient Boussinesq System in Fluid Dynamics with Symbolic Computation

The new soliton solutions for the variable-coefficient Boussinesq system, whose applications are seen in fluid dynamics, are studied in this paper with symbolic computation. First, the Painleve analysis is used to investigate its integrability properties. For the identified case we give, the Lax pair of the system is found, and then the Darboux transformation is constructed. At last, some new soliton solutions are presented via the Darboux method. Those solutions might be of some value in fluid dynamics.     

开放简并二能级原子系统F_g=2F_e=1跃迁中的量子相干效应

文章分析了满足Fg=2Fe=1跃迁的开放简并二能级原子系统在磁场作用下的量子相干效应。该模型中,驱动场的偏振方向平行于磁场方向且与探针光偏振方向相互垂直。由于驱动场和塞曼分裂对原子的耦合作用,在不同驱动场拉比频率作用下将会分别出现电磁诱导透明(EIT)和电磁诱导吸收(EIA)效应,同时伴随相应的正常色散和反常色散。通过控制驱动场强度可以有效控制系统的量子相干效应,同时实现光速调控。