盐水-水的小孔周期性泄流实验与分析

通过对盐水-水小孔周期性泄流的实验研究,对孔径为1.32 mm的8种不同孔长进行测量,得出周期正比于孔长的1.1±0.1次方,同时对孔径为1.32 mm孔长为113.00 mm条件下的内筒液面跟踪记录得出实验曲线为指数形式,与理论分析符合得较好.     

对酒精-水小孔周期性泄流的实验与分析

介绍酒精-水周期性泄流实验的装置,阐述实验现象,记录实验数据并进行归纳整理,用计算机软件描绘图形,通过反复实验和分析,得出与以往盐水-水等不一样的酒精-水小孔周期性泄流的振荡规律.     

小孔周期性泄流的实验与分析

通过对小孔泄流的周期性研究．发现泄流周期随着时间进程变化趋于增大，小孔的直径越大泄流周期越小,不相容的液体间不能形成小孔周期性泄流，并分析了有关现象．     

小孔持续周期性泄流的实验与观测

对小孔周期性泄流实验进行了研究,发现小孔周期性泄流的形成除了与实验装置内外筒液体的浓度、黏度和相容性有关外,还与内外筒之间的空隙有关;周期的大小不但与内外筒液体的浓度、小孔孔径有关,还与内外筒的直径有关.     

油气水三相流段塞流不稳定周期轨道探寻

将临近点回归方法与自适应阈值法相结合, 对油气水三相流段塞流进行了不稳定周期轨道探寻分析, 发现乳状段塞流比水包油段塞流的低阶不稳定周期轨道周期更长. 水包油段塞流的低阶轨道由内部小循环到外部大循环的嵌套结构组成, 乳状段塞流的低阶轨道则由两个平滑的大循环嵌套而成. 结合时频域分析, 发现水包油段塞流的能量分布弥散、频谱范围较宽且频率成分复杂, 而乳状段塞流的能量分布较集中、高频成分较少, 证实水包油段塞流比乳状段塞流流动机理更为复杂, 且时频域分布与低阶不稳定周期轨道结构相对应. 关键词： 油气水三相流段塞流 不稳定周期轨道 自适应阈值 时频分布     

水平管内油气水三相流分流型阻力特性实验研究

对水平管内油气水三相流的摩擦阻力压降特性进行了实验研究,水平管实验段由有机玻璃管制成,内径为40mm,所用的实验工质为:46#机械油,自来水和空气。油、气、水三相的折算速度范围分别为:0.05-0.51m／s、0.05-1.51m／s、0.02-50.6 m／s。按照气液界面总体特征将水平管内油气水三相流的流型分为泡状流、间歇流(段塞流和弹状流)、分层流及环状流。对各种典型流型下的摩擦阻力压降应用改进的Chisholm关系式及油水两相压降关系式进行分析,对Chisholm关系式中的参数C进行了重新定义。发现改进的Chisholm关系式能够较好地对管内油气水三相摩阻压降进行预测,因此改进Chisholm关系式可以作为摩擦压降计算的通用关系式。     

油气水三相流中的复杂相态及压力降研究

将水平管划分为三个测量段,以空气、水和高粘度油体为工质,研究了油气水三相流中由流动引起的液－液复杂相态及其所对应的三相流压力降。试验研究发现,油气水三相流在三个测量段中可由流动引起不同的液－液相态,致使对应于相同的油、气、水三相体积通量,三相流阻力损失存在多值性。对不同的液－液相态建立了与之适应的阻力损失计算模型,模型预测结果与试验结果吻合     

环状集输水平管内油-气-水三相流流型试验研究

目前我国东部陆上油田大部分已进入特高含水采油期,绝大多数油井综合含水率已超过85%,部分油井已达到95%。油-气-水三相流型是特高含水混输技术界限确定、水力热力计算方法研究及集输系统科学运行管理的基础。为了研究大庆低渗透油田环状集输水平管道内油-气-水三相流型,研制一套流型试验装置,进行了一系列试验研究,获得了1360组油气水三相流型图及相应的流动参数。对采集到的流型及试验数据进行分析,首次总结出水平环状集输管道中油-气-水三相流的五种流型,分别为分层流、三层扰动流、波浪冲击流、气弹掺混流和完全掺混流。同时给出了每种流型对应的参数范围,并对每种流动形态及典型特征进行了解释。     

水斗非定常自由水膜流三维贴体数值模拟

本研究采用水斗三维非正交贴体坐标系进行了非定常自由水膜流动的数值解析。对不规则水斗内表面采用三维非正交贴体坐标系下离散点进行拟合,推导了曲面离散点的法向矢量和曲面微元面高斯曲率、平均曲率等几何特征量的计算公式,进而导出流体粒子在运动方向上曲率计算式。在水斗三维贴体坐标系中,还推导了流体粒子在水斗曲面上的运动控制方程。最后对某水轮机水斗内表面非定常自由水膜流进行了数值模拟,得到其非定常水膜流态分布。     

水窗波段反射式偏振光学元件的设计和制作

水窗波段是软X射线进行生物活细胞显微成像的最佳波段,因此对于水窗波段偏振光学元件的研究有着非常重要的意义。用菲涅耳公式计算出在水窗波段内不同材料组合对应不同波长的最大反射率,模拟分析了多层膜周期和表界面粗糙度对多层膜偏振光学元件性能的影响。用超高真空磁控溅射镀膜设备,制作出2．40nm、3．00nm和4．30nm波长处W／B4C多层膜偏振元件,并用X射线衍射仪对元件的周期厚度进行了测量,得到的测量结果与设计值偏差很小,可以进行实际应用。为水窗波段反射式偏振光学元件的研究提供了理论依据,同时也为相应偏振光学元件的制备确定了合适的工艺参量。     

Mode hopping in single-mode microchip Nd：YAG lasers induced by optical feedback

The mode hopping phenomenon induced by optical feedback in single-mode microchip Nd：YAG lasers is presented. With optical feedback, mode hopping strongly depends on two factors： the ratio of external cavity length to intra-cavity length, and initial gains of the two hopping modes, When external cavity length equals an integral multiple of intracavity length, there is almost no mode hopping. However, if the external cavity length does not equal an integral multiple of intra-cavity length, mode hopping occurs. The ratio of external cavity length to intra-cavity length determines the position of two-mode hopping, The initial gains of the two hopping modes determine the corresponding peak values and oscillating periods of them in the intensity modulation curves.     

基于微观结构的Cu互连电迁移失效研究

提出了一种基于微观晶粒尺寸分布的Cu互连电迁移失效寿命模型. 结合透射电子显微镜和统计失效分析技术, 研究了Cu互连电迁移失效尺寸缩小和临界长度效应及其物理机制. 研究表明, 当互连线宽度减小, 其平均晶粒尺寸下降并导致互连电迁移寿命降低. 小于临界长度的互连线无法提供足够的空位使得铜晶粒耗尽而发生失效. 当互连长度大于该临界长度时, 在整个电迁移测试时间内, 部分体积较小的阴极端铜晶粒出现耗尽情况. 随着互连长度的增加该失效比例迅速增大, 电迁移失效寿命减小. 当互连长度远大于扩散长度时, 失效时间主要取决于铜晶粒的尺寸, 且失效寿命和比例随晶粒尺寸变化呈现饱和的波动状态. 关键词： Cu 互连 电迁移 微观结构     

Intensity tuning characteristics of double-mode He--Ne laser with optical feedback

This paper investigates the intensity tuning characteristics of a double longitudinal modes He--Ne laser subjected to optical feedback. The intensity undulations of the total light and the two modes are observed for different external cavity length. Two modulations of the internal cavity length are performed. One is only for the internal cavity length being modulated and the other is for both the internal and the external cavity length being modulated. The undulation frequency of the total light is found to be determined by the ratio of external cavity length to internal cavity length in both modulations. When the external cavity length is integral times of the internal cavity length, the fringe frequency of the total light could be seven or even more times of that in conventional optical feedback. A simple theoretical analysis is presented, which is in good agreement with the experimental results. The potential use of the experimental results is also discussed.     

TE01-TE11模式转换器的带宽特性

针对模式转换器设计中在相同的中心频点转换效率下模式转换器越短带宽越宽的传统观点,研究发现了最佳长度的存在,即当结构长度大于最佳长度时,带宽随着结构长度增加而减小,当结构长度小于最佳长度时,带宽随着结构长度增加而增加。通过对中心频率35 GHz、半径13.6 mm的TE01-TE11模式转换器进行的验证发现,最佳长度为550 mm,此时带宽达到最大值6.28%。     

Length dependence of rectification in organic co-oligomer spin rectifiers

The rectification ratio of organic magnetic co-oligomer diodes is investigated theoretically by changing the molecular length. The results reveal two distinct length dependences of the rectification ratio: for a short molecular diode, the chargecurrent rectification changes little with the increase of molecular length, while the spin-current rectification is weakened sharply by the length; for a long molecular diode, both the charge-current and spin-current rectification ratios increase quickly with the length. The two kinds of dependence switch at a specific length accompanied with an inversion of the rectifying direction. The molecular ortibals and spin-resolved transmission analysis indicate that the dominant mechanism of rectification suffers a change at this specific length, that is, from asymmetric shift of molecular eigenlevels to asymmetric spatial localization of wave functions upon the reversal of bias. This work demonstrates a feasible way to control the rectification in organic co-oligomer spin diodes by adjusting the molecular length.     

部分空间和部分光谱相干高斯-谢尔模型脉冲光束在自由空间中的光谱和时间特性

 对部分空间和部分光谱相干２维高斯-谢尔模型脉冲光束在自由空间传输的光谱和时间特性做了详细的数值研究。结果表明,部分空间和部分光谱相干高斯-谢尔模型脉冲光束在自由空间传输中发生了光谱移动,光谱移动与场点位置、空间相关长度和时间相干长度有关。在轴上,光谱出现蓝移,相对光谱移动随传输距离的增加而增大,随空间相关长度和时间相干长度的增加而减小,并逐渐趋于一定值。在轴外,光谱出现蓝移和红移,并与空间相关长度和时间相干长度有关。脉冲时间波形不变,对所得主要结果做了物理解释。     

Relation of single-pulse characteristics to length of active rod

The population inversion as a function of rod length is examined for ruby and neodymium glass. The stored energy per unit length falls first on account of noise and then from oscillation due to reflection from the ends; this causes a maximum in the relation of radiated power to length. Estimates are given for the maximal stored energy, the optimum length, the maximum power output, and the limiting pulse length.     

Lifetime and path length of the virtual particle

The concepts of the lifetime and path length of a virtual particle are introduced. It is shown that, near the mass surface of the real particle, these quantities constitute a 4-vector. At very high energies, the virtual particle can propagate over considerable (evenmacroscopic) distances. The formulas for the lifetime and path length of an ultrarelativistic virtual electron in the process of bremsstrahlung in the Coulomb field of a nucleus are obtained. The lifetime and path length of the virtual photon at its conversion into an electron-positron pair are discussed. The connection between the path length of the virtual particle and the coherence length (formation length) is analyzed.     

Screening and fundamental length scales in semidilute Na-DNA aqueous solutions

The fundamental length scales in semidilute Na-DNA aqueous solutions have been investigated by dielectric spectroscopy. The low- and the high-frequency relaxation modes are studied in detail. The length scale of the high-frequency relaxation mode at high DNA concentrations can be identified with the de Gennes-Pfeuty-Dobrynin correlation length of polyelectrolytes in semidilute solution, whereas at low DNA concentrations and in the low added salt limit the length scale shows an unusual exponent reminiscent of semidilute polyelectrolyte chains with hydrophobic backbone. The length scale of the low-frequency relaxation mode corresponds to a Gaussian chain composed of correlation blobs in the low added salt limit, and to the Odijk-Skolnick-Fixman value of the single chain persistence length in the high added salt limit.     

Sound transmission characteristics of Tee-junctions and the associated length corrections

The sound transmission characteristics of a Tee-junction formed by a sidebranch and an infinitely long duct are investigated numerically using the finite element method. The associated corrections of the branch length and the upstream duct length are also discussed in detail. The types of branch resonance that result in strong or weak sound transmission across the junction are determined and their effects on the length corrections examined. Results suggest that the type of sidebranch, the branch width, the branch length, and the order and the form of the resonance affect more significantly the length corrections of the duct section. The excitation of nonplanar higher branch modes gives rise to rapid increase in the duct length corrections and also results in lower sound transmission.