C_2H_4分子红外吸收特性的光声探测

用ＴＥＡＣＯ２激光做激发源，用光声法检测了９．２～１０．８μｍ波长范围内Ｃ２Ｈ４分子的红外吸收特性，获得了Ｃ２Ｈ４分子的单脉冲激光光声谱，它与Ｃ２Ｈ４分子的红外吸收谱及光热谱符合的较好；并用光声法测得了样品气体中的声速及Ｃ２Ｈ４分子的Ｖ－Ｔ驰豫时间。     

Steering attosecond electron wave packets with light

Photoelectrons excited by extreme ultraviolet or x-ray photons in the presence of a strong laser field generally suffer a spread of their energies due to the absorption and emission of laser photons. We demonstrate that if the emitted electron wave packet is temporally confined to a small fraction of the oscillation period of the interacting light wave, its energy spectrum can be up- or downshifted by many times the laser photon energy without substantial broadening. The light wave can accelerate or decelerate the electron's drift velocity, i.e., steer the electron wave packet like a classical particle. This capability strictly relies on a sub-femtosecond duration of the ionizing x-ray pulse and on its timing to the phase of the light wave with a similar accuracy, offering a simple and potentially single-shot diagnostic tool for attosecond pump-probe spectroscopy.     

Direct visual observation of thermal capillary waves

We studied the free fluid-fluid interface in a phase-separated colloid-polymer dispersion with laser scanning confocal microscopy and directly observed thermally induced capillary waves at the interface in real space. Experimental results for static and dynamic correlation functions validate the capillary wave model down to almost the particle level. The ultralow interfacial tension, the capillary length, and the capillary time are found to be in agreement with independent measurements. Furthermore, we show that capillary waves induce the spontaneous breakup of thin liquid films and thus are of key importance in the process of droplet coalescence.     

丘陵区土壤颗粒的分形维数及其应用

通过对四川省宜宾地区 2 3个耕层土样的颗粒组成分析 ,分别应用AR法和杨培岭法计算了不同质地的颗粒的分形维数 ,其结果是砂壤土、轻壤土、中壤土、重壤土和粘土分形维数的平均值依次递增。回归相关分析表明土粒分形维数与粒径 0 0 5～ 1 0 0mm颗粒含量关系显著负相关 ,与 0 0 1～ 0 0 5mm和 0 0 0 5～ 0 0 1mm颗粒含量关系不显著 ,与 0 0 0 1～ 0 0 0 5mm和小于 0 0 0 1mm颗粒 (粘粒 )含量呈极显著正相关 ;它们与有机质呈显著正相关 ,与土壤容重呈极显著负相关。分形维数可作为土壤质地的综合性的定量化指标     

利用GUS瞬时表达探讨香石竹品种“云红二号”基因枪转化参数

利用基因枪法和带有GUS基因的双元表达载体pBI121转化香石竹品种"云红二号"的外植体。通过检测GUS基因在香石竹叶片和茎段上的瞬时表达情况,分析受体材料、轰击距离及氦气压力对GUS瞬时表达的影响。结果表明,以茎段为受体材料,在射程为6 cm、氦气压力为1100 psi下,可检测到GUS基因较好的表达活性,瞬时表达率最高可达8.33%。     

液柱分离对管道的危害及其预防

管道发生水击时的水击压力波对管道的危害非常严重。在分析水击形成原因的基础上，讨论了液柱分离形成的过程及其对管道的影响，结合实例，利用公式推导计算出管道在发生水击过程中的水击压力，提出了避免出现油品液柱分离的具体措施。     

管道输送系统液体弹性波防蜡防垢特性研究

考察了同田管输送系统任一截面上的速度分布，流量与压力梯度的关系，研究了高，低切变率流动中颗粒的运动规律及径向迁移理论，指出无论颗粒最初位置在何处，在高切变率流动场中颗粒都向离管轴约０．６Ｒ（半径）处的平衡位置移动，并且迁移速度随雷诺数增大而增大，根据以上理论结合管输系统流体的振动规律，研究了防垢防蜡机理。     

Research with high-power short-wavelength lasers

Three high-temperature, high-density experments were conducted recently with the 10-terawatt, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. The experiments demonstrated successful solutions to problems that arose during previous laser-plasma interaction experiments with long-wavelength (greater than 1 micrometer) lasers: (i) large-scale plasmas, with dimensions approaching those needed for high-gain inertial fusion targets, were produced in which potentially deleterious laser-plasma instabilities were collisionally damped; (ii) deuterium-tritium fuel was imploded to a density of 20 grams per cubic centimeter and a pressure of 10(10) atmospheres under the improved laser conditions, and compression conditions (preheating and pressure) were consistent with code calculations that predict efficient (high-gain) burn of a large thermonuclear fuel mass when driven with a large, short-wavelength laser; and (iii) soft x-rays were amplified by a factor of 700 by stimulated emission at 206 and 209 angstroms (62 electron volts) from selenium ions in a laser-generated plasma. These small, short-pulse x-ray sources are 10(10) to 10(11) times brighter than the most powerful x-ray generators and synchrotron sources available today. The plasma conditions for these experiments were made possible by advances in Nd:glass laser technology, in techniques to generate efficiently its short-wavelength harmonics at 0.53, 0.35, and 0.26 micrometers, and in diagnostic and computational modeling.     

三层成层水域内波的研究

运用小振幅波理论对三层成层水域内波运动进行了解析,阐明了三层成层状态下的流速垂直分布和内波波动分散规律,并与大阪湾观测到的内波列取得良好吻合,解析还表明,三层成层水域流速的大小与内波引起各层间的流量分配密切相关,最大振幅水深由水域的成层特点所决定,小流速时的内波界面变位和流况与二层成层的情形呈形完全相反的结果,了解三层成层水域内波的这些特性对于正确认识养殖水域的环境特点及变动,合理设置水产增养殖设     

三层成层水域内波的研究

运用小振幅波理论对三层成层水域内波运动进行了解析,阐明了三层成层状态下的流速垂直分布和内波波动分散规律,并与大阪湾观测到的内波列取得良好吻合,解析还表明,三层成层水域流速的大小与内波引起各层间的流量分配密切相关,最大振幅水深由水域的成层特点所决定,小流速时的内波界面变位和流况与二层成层的情形呈形完全相反的结果,了解三层成层水域内波的这些特性对于正确认识养殖水域的环境特点及变动,合理设置水产增养殖设     

Fractal Characteristics of Stagnic Anthrosols and the Relationship with Soil Micro-Structure

The Stagnic Anthrosols developed from quaternary yellow sedimentary parent material occupied an important position in Southwest China. Fractal dimensions of particle size and micro-aggregate size distributions of Stagnie Anthrosols and their relationship to soil micro-structure had been probed. Results showed that the soil particle size distributions were dominated by clay, the fractal dimensions of particle size distributions （Ds） were high and between 2.676-2.925, as the fractal dimensions of micro-aggregate size distributions （Da） were between 2.354-2.853. The fractal dimensions of particlesize distributions were preferably related with the ratio of coarse particles and fine particles （c/f20 ,m） and the micromorphological feature of skeleton grains. The evolution degree of micro-structure among horizons were reflected by the coefficient of variation of Ds within the profile. The fractal dimensions of micro-aggregate size distributions were related with the quantities, distributions of micro-aggregates and micro-pores. Results revealed that the soil micro-structures could be quantified by fractal dimensions preliminarily.     

长期不同施肥红壤粒径分布的多重分形特征

【目的】通过探讨长期不同施肥后红壤粒径分布非均匀性和异质性的变化特征,揭示不同施肥模式对土壤粒径分布的影响,为农田土壤发育过程以及科学合理利用红壤提供理论支撑。【方法】以湖南省祁阳试验点红壤旱地长期定位试验（1990年至今）为依托,采用激光粒度分析仪测定1990年初始土样（O）与连续22年不施肥（CK）、单施化肥（NPK）、有机无机配合施用（NPKM）和单施有机肥（M）4种施肥模式下小麦-玉米轮作系统中耕层土壤（0-20 cm）颗粒分布;应用多重分形理论以盒计维方法分析了土壤粒径分布多重分形参数的变化趋势;并对多重分形参数、土壤颗粒与土壤有机质进行相关性分析,阐明多重分形参数表征土壤粒径分布的精准性。【结果】多重分形参数可以反映土壤粒径分布的非均匀程度,与红壤黏、粉粒含量、土壤有机质含量显著相关;运用多重分形参数表征土壤粒径分布具有较高的灵敏性与精准度。红壤粒径广义维数（D(q)）在﹣10≤q≤10的范围内,其中D(q＜0)比D(q＞0)更为敏感,表明广义维数（D(q)）在稀疏区域的标度性低于密集区域的标度性。与初始土样（O）相比,长期不同施肥对容量维数（D0）与信息维数（D1）无显著影响,但显著提高了关联维数D2（0.864-0.883）、D1/D0（0.921-0.932）;处理间均表现为M、NPKM＞NPK、CK、O,也显著提高了奇异强度α0（1.129-1.177）和奇异谱宽Δα（1.966-2.707）等多重分形参数,处理间均表现为NPK、CK＞M、NPKM＞O。【结论】在成土条件、种植制度和管理措施均一致的条件下,无论是单施有机肥（猪粪）还是有机肥（猪粪）配合施用化肥均可以显著提高红壤粒径分布局部密集程度,促进土壤细化,加快土壤不均匀性发展,增强了土壤颗粒异质性。多重分形参数可以表征土壤粒径分布的细微差别,为土壤粒径分布的精准研究提供了技术支持。     

多相流管道输量突增的瞬态效应试验研究

在大型多相流环道上进行了液量增加的瞬态试验，讨论了试验中的瞬态效应。当液相流量快速增加后，压力波首先传播到管道各点，压力发生扰动，一般时间后空隙传播到各点，压力快速上升。压力快速变化向下游的传播速度等于空隙波的波速。在段塞流时，空隙波波速等于液塞运动速度，在分层流时，空隙波波速等于液体实际流速；在气团流时，空隙波波速等于气液混合物的速度。差压的变化较为复杂，在不同流型和液量下的变化不同。     

Two-dimensional rare gas solids

Monolayers of rare gas atoms adsorbed onto the basal planes of graphite play the same prototype role in two dimensions that rare gas liquids and solids do in three dimensions. In recent experiments such novel phenomena as continuous melting, the lack of true crystallinity in two dimensions, orientationally ordered fluid phases, and melting from a solid to a reentrant fluid with decreasing temperature have been observed. Because the forces in these rare gas monolayers are simple and well understood, by studying them the investigator can examine a direct interface between experiment and first principles. In order to understand the phases and phase transitions that occur in such materials, it is necessary to consider the geometrical matching of the rare gas overlayer to the graphite substrate. It turns out that in two dimensions both the local and the long-distance behavior are important. These two-dimensional rare gas solids may be effectively probed with synchrotron x-ray techniques, and the results of a series of synchrotron x-ray scattering studies of these solids are presented.     

High-resolution nuclear magnetic resonance spectroscopy in a circularly polarized laser beam

Nuclei in a fluid subjected to a continuous wave circularly polarized light beam are predicted to experience a static magnetic field proportional to E(+/-) x E(+/-), where E(+/-) is the electric vector of the right or left circularly polarized wave and the dot denotes a time derivative. The field strongly depends on the local electronic structure and is present in all atoms. For an intensity of 10 watts per square centimeter propagating in the direction of the field of a magnetic resonance spectrometer, the general theory presented here predicts shifts of +/- 4 x 10(-8) hertz for protons and +/- 10(-5) hertz for fluorine-19. Larger shifts are predicted if the laser frequency is near an optical absorption.     

气固两相流管道流动阻力特性数值模拟

为掌握气固两相流的流动阻力特性,利用计算流体动力学软件CFX,对直管段及水平弯管进行气固两相流数值模拟。采用欧拉一拉格朗日法选择数值模拟计算模型,根据模拟对象工况,确定软件模拟条件。通过模拟,对管道系统的特性、操作条件、物料和气体的性质等影响气固两相管流压力损失的主要因素进行了探讨,对连续相速度和压力分布特性以及颗粒运动轨迹进行了分析,得到了气固两相管流的压力场、速度场分布,颗粒在管内的分布情况和运动轨迹,以及不同工况条件下的系统阻力和颗粒沉积量分布规律,并确定了在特定条件下能耗最小的经济流速。研究成果可为气固两相流的工程设计和理论研究提供参考。（图18,表2,参10）。     

Monitoring the number and size of pests based on modulated infrared beam sensing technology

In order to identify the number and size of pests, a sensor based on modulated infrared sensing technology with narrow-line laser beam was developed. A mathematical model between the light current change and time was established when a pest passed through the sensor. This model indicated that the factors that influence light current change not only involved the pest dimensions but also other dimensions, such as the width of narrow-line laser beam and the height between the taper collecting mouth and the narrow-line laser beam. Therefore, information on pest numbers and dimensions, obtained from similar sensors in previous literature was inaccurate. However, quantitative analysis of the model showed that the external dimensions could be neglected if an appropriate width of the narrow-line laser beam was selected. Hence, it was set at 0.0005 m in this sensor. Experimental results indicated that the sensor could eliminate the influence of ambient light and had a good precision of pest counting and classifying, which were larger than 98 and 86.7% respectively.     

超临界CO2流体萃取核桃油工艺条件的研究

由于核桃油中不饱和脂肪酸含量很高 ,核桃蛋白又容易变性 ,所以普通的油脂制取方法对该产品品质有不利的影响 .根据核桃油的品质特性 ,该试验对超临界CO2 流体萃取核桃油的工艺条件进行了研究 .通过对萃取压力、萃取温度、物料粒度、萃取时间 4个操作条件的试验探索 ,得出了最佳操作工艺参数 :压力 32MPa、温度 4 0℃、物料粒度 30目 (即粒径约为 0 5mm)、萃取时间 3 5h .采用该工艺制取的核桃油完全可以达到一级食用油标准 ,也符合欧洲经济共同体 (EEC)对核桃油的要求 .     

植物暗适应叶的放氧动力学(Ⅰ)——光声放氧动力学

用光声光谱仪检测结果表明 ,暗适应叶在光诱导期间出现非常复杂的光声瞬态放氧 ,产生了一种称为氧峰(oxygengush)的现象 .该文利用自制的光声仪对暗适应菠菜叶在光诱导期间出现的光声瞬态放氧与暗适应时间关系 ,远红光、饱和光预处理以及高浓度CO2 对光声瞬态放氧的影响 ,光声热信号与光声放氧信号之间的关系作了初步研究 .推测由两个组分组成的氧峰与其动力学可能反映光系统Ⅱ的状态     

气量增加段塞流场中压力波传播特性分析

利用改进后的段塞流跟踪模型对水平管道气量瞬变空气-水段塞流场中的压力波传播特性进行了模拟研究,分析了压力波沿管道的变化规律以及入口初始液相流量和气相流量的变化量对压力波速的影响,并将模型模拟结果与大型多相流试验环道上的试验结果进行了比较.结果表明,该模型能够有效地模拟气量瞬变段塞流场中压力波的传播特性;压力波速沿管道具有衰减特性;气量增加过程中的增压波速沿管道的衰减速率是逐渐降低的.