含双圆柱亚表面缺陷板条材料的表面温度分布

基于非傅里叶热传导方程,采用复变函数法和镜像法,研究了含双圆柱亚表面缺陷板条材料热波散射的温度场,并给出了热波散射温度场的解析解。分析了入射波波数、热扩散长度、缺陷的埋藏深度以及板条材料的厚度等对板条表面温度分布的影响。温度波由调制光束在材料表面激发,缺陷表面的边界条件为绝热。该分析方法和数值结果可为工程材料结构的传热分析、热波成像和材料内部缺陷评估,以及热物理反问题研究提供参考。     

地表反照率对短波红外探测大气CO2的影响

在卫星短波红外遥感二氧化碳的过程中, 表征地表特征的地表反照率是影响探测精度的重要参数之一. 针对温室气体二氧化碳高精度探测的需求, 本文研究了地表反照率对正演模拟光谱和反演近地面二氧化碳平均柱浓度XCO₂的影响. 模拟计算结果显示, 地表反照率数值增大时, 观察的光谱强度也相应增大, 并且在O₂-A波段造成的光谱差异比1.6 μm波段高出一个数量级, 即地表反照率在O₂-A波段的影响比较大. 选取了两个不同地表类型的实际观测光谱, 仅改变O₂-A波段和1.6 μm波段地表反照率数值, 得出草地点在O₂-A波段地表反照率达到0.25的误差时, 会给XCO₂的反演结果造成大于1%的相对误差, 而1.6 μm波段的地表反照率变化对XCO₂的反演结果造成的误差可以忽略不计, 说明了地表反照率在反演XCO₂过程中的重要性主要来自对O₂-A波段的影响. 此研究表明了地表反照率在卫星遥感温室气体过程中的重要性, 为提高遥感探测二氧化碳的精度提供了重要的理论依据和指导.     

上甸子区域大气本底站NO2柱浓度光谱反演及其变化特征

为了探究京津冀本底浓度地区NO₂这一重要空气污染物的变化特征,采用多轴差分吸收光谱技术（MAX-DOAS）在上甸子区域大气本底站开展了太阳散射光谱观测以及NO₂柱浓度反演研究。在NO₂的405～430nm特征谱段进行了定量光谱解析,并通过几何近似法计算了2009年7～9月NO₂对流层垂直柱浓度（VCD_trop）。观测期间NO₂ VCD_trop平均值和最大值分别为5.43×1015和7.15×1016 molec·cm-2。NO₂ VCD_trop日均值浓度水平较低,但总体上有上升趋势。NO₂ VCD_trop变化过程与风速风向关系密切：西南风时风速越小NO₂ VCD_trop越低,东北风对NO₂ VCD_trop有扩散稀释作用。NO₂ VCD_trop日变化形态总体上呈现为中午时段低、早晚较高的特征,并且傍晚峰值比早间峰值略高。上甸子站NO₂ VCD_trop浓度水平和日变化幅度相比北京城区同期观测结果明显偏小。NO₂ VCD_trop变化特征与河北香河和固城等污染相对较轻站点观测到的变化特征相一致。总之,MAX-DOAS能够有效监测区域本底大气的NO₂ VCD_trop,其变化特征与工业和交通排放、大气光化学过程、大气传输等复杂因素有关,还需积累更多数据和深入研究。     

不同临界保留因子下天然有机物亲疏水组分光谱特性

吸附树脂层析法是表征环境水样有机物亲疏水组分分布的常用方法。作为柱层析的基本参数,临界保留因子对亲疏水物质的吸附及分离效果具有潜在影响。以河北某水库的水样为例,将有机物分为亲水物(HIS)、疏水酸(HOB)、疏水碱(HOA)和疏水中性物(HON),考察了在不同临界保留因子分离条件下(k′_cr=5, 10, 25, 50, 100)亲疏水组分有机物含量分布,并着重考察了其光谱学特性。研究发现,亲疏水组分的浓度分布取决于k′_cr值的设置,疏水组分的比例和疏水程度随k′_cr的增大而增大。在250~280 nm波长范围内,亲水组分HIS的紫外吸光度随k′_cr的增高而增高,而疏水组分HOA和HOB则呈现相反趋势,亲水与疏水组分之间的紫外光谱差异性随k′_cr增大而增大。此外,疏水组分单位质量浓度的吸光度对k′_cr的取值敏感,推测k′_cr可能影响所得组分的芳香族官能团性质。进一步考察了各组分的三维荧光光谱,并采用荧光区域积分和荧光指数对图谱进行解析。结果表明,亲疏水组分的荧光峰形态、荧光区域分布和荧光团密度与k′_cr值有关,荧光指数BIX,HIX_em和Peak T/C对k′_cr的取值敏感,说明k′_cr可能对所得组分的具体化学组成乃至迁移转化行为产生影响。因此在分离并表征环境水样的亲疏水组分分布时,应特别注意临界保留因子的设置并明确标明其取值。     

Transient Reorientation of a Doped Liquid Crystal System under a Short Laser Pulse

The transient optical nonlinearity of a nematic liquid crystal doped with azo-dye DR19 is examined. The optical reorientation threshold of a 25-μm-thick planar-aligned sample of 5CB using a 50 ns pulse duration 532nm YAG laser pulse is observed to decrease from 800 mJ/mm^2 to 0.6 mJ/mm^2 after the addition of i vol% azo dopant, a reduction of three orders of magnitude. When using a laser pulse duration of 10ns, no such effect is observed. Experimental results indicate that the azo dopant molecules undergo photoisomerization from trans-isomer to cis-isomer under exposure to light, and this conformation change reorients the 5CB molecules via intermolecular coupling between guest and host. This guest-host coupling also affects the azo photoisomerization process.     

考虑空气柱的水力旋流器内流场的数值模拟

对水力旋流器内流场进行了数值模拟.旋流器内液相和气相的湍流模拟采用了雷诺应力模型(RSM),边界条件采用速度进口、压力出口.在同一工况下选用三维模型及二维简化模型、分别用VOF模型及刚盖法对空气柱进行处理,就空气柱形成、切向及轴向速度与相同条件下试验测量的结果进行比较.结果表明,三维模型计算结果较二维简化模型与实验值吻合得更好,但二维简化模型在降低精度不大的前提下大大减少了计算时间.对空气柱的处理,选用VOF模型得到的结果更准确,而刚盖法减少了计算用时.     

Some Magnetized Bulk Viscous String Cosmological Models in Cylindrically Symmetric Inhomogeneous Universe with Variable ∧-Term

Some cylindrically symmetric inhomogeneous viscous fluid string cosmological models with magnetic field and cosmological term A varying with time are investigated. To get the deterministic solution, it has been assumed that the expansion （θ） in the model is proportional to the eigen value σ^11 of the shear tensor σ^ij. The value of cosmological constant for the model is found to be small and positive, which is supported by the results from recent supernovae Ia observations. The effect of bulk viscosity is to produce a change in perfect fluid and hence exhibits essential influence on the character of the solution. The physical and geometric properties of the models are also discussed in presence and absence of magnetic field.     

A two-dimensional analytical model for channel potential and threshold voltage of short channel dual material gate lightly doped drain MOSFET

An analytical model for the channel potential and the threshold voltage of the short channel dual-material-gate lightly doped drain （DMG-LDD） metal-oxide-semiconductor field-effect transistor （MOSFET） is presented using the parabolic approximation method. The proposed model takes into account the effects of the LDD region length, the LDD region doping, the lengths of the gate materials and their respective work functions, along with all the major geometrical parameters of the MOSFET. The impact of the LDD region length, the LDD region doping, and the channel length on the channel potential is studied in detail. Furthermore, the threshold voltage of the device is calculated using the minimum middle channel potential, and the result obtained is compared with the DMG MOSFET threshold voltage to show the improvement in the threshold voltage roll-off. It is shown that the DMG-LDD MOSFET structure alleviates the problem of short channel effects （SCEs） and the drain induced barrier lowering （DIBL） more efficiently. The proposed model is verified by comparing the theoretical results with the simulated data obtained by using the commercially available ATLASTM 2D device simulator.     

基于地对空观测光谱的大气CO_2柱浓度反演分析（英文）

基于地对空高光谱观测获取大气CO2柱浓度(大气中CO2的垂直总含量)数据是验证和改进卫星高光谱观测反演CO2浓度的重要数据源之一,而目前在中国还没有基于地面光谱观测进行大气CO2柱浓度反演研究的报告。利用光谱分析仪与太阳跟踪仪等构成的地面观测系统在中国内蒙古锡林郭勒草原进行了地对空高光谱观测,基于高光谱观测数据反演了大气CO2柱浓度。在基于1.6μm大气CO2的光谱吸收特征进行CO2浓度反演过程中,评价分析了观测光谱的波长漂移和气象参数对大气CO2柱浓度反演精度的影响。结果显示观测期间平均大气CO2柱浓度为390.9μg·mL-1。波长的漂移将会导致反演浓度值整体偏低;波长漂移从-0.012~0.042nm范围时,将会导致1μg·mL-1以上的偏差。同时,研究发现光谱透过率在6 357~6 358,6 360~6 361和6 363~6 364cm-1谱段敏感于气象参数的变化。对比利用与光谱观测同时和非同时观测的气象参数进行的浓度反演结果发现,非同时观测气象参数的利用引起的浓度偏差最小在0.11μg·mL-1,最大可达4μg·mL-1;本论文的分析结果对基于光谱反演CO2柱浓度算法的改进有着一定的参考价值。     

短寿命核转轮传送装置

在中国原子能科学研究院的串列式静电加速器上建立了传送短寿命核的转轮装置,可用于鉴别和研究寿命短至几秒的核素．该装置已用于新的缺中子核素９０Ｒｕ的鉴别及其半衰期和衰变γ的测量． A wheel device for transporting short-lived nuclei has been constructed at the HI-13 tandem accelerator of CIAE. The device can be used in the identification and investigation of nuclides with life-times as short as a few seconds. With the aid of this device a new nutron-deficient nuclide 90Ru has been identified. Its half-life and decay γ-rays have been measured.