Laboratory Study on Sediment Diffusion and Deposition into Blind Channels

Any waterway with one end closed and the other open is generally called a blind channel. The main flow tends to expand, separate, and cause circulation at the mouth of blind channels. The main flow continuously transfers momentum and sediment into the circulation region through the turbulent mixing region (TMR) between them, thus leading to a large amount of sediment deposition in the blind channels. This paper experimentally investigated the properties of the water flow and sediment diffusion in TMR, demonstrating that both water flow and sediment motion in TMR approximately coincide with a similar structure as in the free mixing layer induced by a jet. The similarity functions of flow velocity and sediment concentration are then assumed, based on observation, and the resulting calculation of these functions is substantially facilitated. For the kind of low velocity flow system of blind channels with a finite width, a simple formula for the sediment deposition rate in blind channels is established by analyzing the gradient of crosswise velocity and sediment concentration in TMR.

Numerical Analyses of Discrete Gust Response for an Aircraft

Based on Navier-Stokes equations and structural and flight dynamic equations of motion, dynamic responses in vertical discrete gust flow perturbation are investigated for a supersonic transport model. A tightly coupled method was developed by subiterations between aerodynamic equations and dynamic equations of motion. First, under the assumption of rigid-body and single freedom of motion in the vertical plunging, the results of a direct-coupling method are compared with the results of quasi-steady model method. Then, gust responses for the one-minus-cosine gust profile arc analyzed with two freedoms of motion in plunging and pitching for the airplane configurations with and without the consideration of structural deformation.

Experimental Investigation Of Influence Of Interfacial Tension On Convection Of Two-Layer Immiscible Liquid

Benard-Marangoni convections of two-layer fluids heated from the bottom are investigated experimentally with a particle imagine velocimetry. The flows are visualized from the side, and various velocity fields near the onset of convection, such as three-layer vortex convective patterns, are observed when the depth ratio varies in a wide range. A new classification of the convective patterns is proposed with more detail than in previous studies. The analysis of the results indicates that the interface tension greatly influences the motion intensities of the bottom and top layers. The dimensionless wave number increases with the Bond number when the motion in the top layer is not more intense than that in the bottom layer, which agrees with the theoretical prediction.

Statistical-theory of multiphoton excitation of polyatomic-molecules based on the wigner function

This paper is aimed at establishing a statistical theory of rotational and vibrational excitation of polyatomic molecules by an intense IR laser. Starting from the Wigner function of quantum statistical mechanics, we treat the rotational motion in the classical approximation; the vibrational modes are classified into active ones which are coupled directly with the laser and the background modes which are not coupled with the laser. The reduced Wigner function, i.e., the Wigner function integrated over all background coordinates should satisfy an integro-differential equation. We introduce the idea of ``viscous damping'' to handle the interaction between the active modes and the background. The damping coefficient can be calculated with the aid of the well-known Schwartz–Slawsky–Herzfeld theory. The resulting equation is solved by the method of moment equations. There is only one adjustable parameter in our scheme; it is introduced due to the lack of precise knowledge about the molecular potential. The theory developed in this paper explains satisfactorily the recent absorption experiments of SF6 irradiated by a short pulse CO2 laser, which are in sharp contradiction with the prevailing quasi-continuum theory. We also refined the density of energy levels which is responsible for the muliphoton excitation of polyatomic molecules.

蒙特卡罗模拟四极阱中原子的参变激发

在中性原子的磁囚禁实验中,磁阱线圈的电流噪声会激发磁阱中的原子运动,势必对原子团的温度和寿命产生不可忽视的影响。对于非简谐阱,这种激发具有能量选择特性,它又取决于电流噪声的频谱分布。选择了实验中常用的四极阱为研究对象,用直接模拟蒙特卡罗方法来模拟四极阱中原子运动的参变激发现象,得到了原子温度与原子数损失随激发频率的变化关系,并进一步计算了两个共振峰处原子温度随调制时间和调制深度的变化曲线。此外,还研究了弹性碰撞速率对参变激发过程中原子温度上升的影响。这些结果对四极阱参变激发的实验有较好的参考价值。

Electronic transport through self-assembled quantum disks

In this paper we study a single electron tunneling through a vertically stacked self-assembled quantum disks structure using a transfer matrix technique in the framework of effective mass approximation. In the disks, the electron is confined both laterally and vertically; we separate the motion in the vertical and lateral directions within the adiabatic approximation and treat the energy levels of the latter as an effective confining potential. The influence of a constant applied electric field is taken into account using an exact Airy-function formalism and the current density is calculated at zero temperature. By increasing the widths of the barriers, we find the peaks of the current density shift toward lower voltage region; meanwhile, they can become even sharper. (C) 2004 Elsevier Ltd. All rights reserved.

形变原子核系统中的量子混沌运动的研究

按照玻尔的对应原理，将量子力学应用到宏观运动上所得的结果应该与经典力学的结果一致。故而力学系统的混沌特征也必然要在其量子性质上有所表现。迄今，对量子混沌运动研究多局限于研究经典上混沌的系统对应的量子系统有什么量子表现，但这些量子表现的动力学根源仍然不清楚。应用量子可积系统H_0的最小测不准度态作为初绐态，研究了在扰动哈密顿量作用下波包随时间、空间的演化特征。在完全的量子力学动力学描述框架下，量子波包的空-时演化表现了与经典力学中一一对应的对初值的敏感性。对自治的哈密顿系统，选定初始位置的波包始终分布在确定的能区内。起始于经典上混沌的相空间内的相干态，在其时空演化时，所包含的能级呈现GOE分布，能级之间存在着大量的免交叉。免交叉处两能级对应的态函数发生强混杂，呈现非线性共振，因而态函数发生突变。正由于波包中一对对相邻能级、状态之间的这种非线性其振的出现，在确定的动力学方程描述下的波包的确定的空时演化特征变得非常复杂，以至于成为混沌的。我们用系统中一组完备的动力学变量的期望值及其相应的测不准度来描述波包在量子空间的拓扑性质。因此，量子混沌运动可以用与量子规则运动对比的方法进行研究，并用其渐近行为表示其特征。数值计算的结果表明，量子可积系统的最小测不准态波包的空时演化动力学性质确实表现了与相应的经典系统对应的初值敏感性及波包扩展宽度随时间指数式的扩散行为，后者保证了系统的混杂性。而在混杂之后，即波包宽度随时间指数式扩散之后，宽度达到稳定。这时，波包中各状态的分布趋于各态历经。由于采用了徐躬耦先生所建议的等效普朗克常数，我们的结果可方便地推广到经典极限。因此可明确地区分波包的空时演化特征中的量子效应和动力学效应。

CSR纵向运动研究

论文对建造中的兰州重离子加速器冷却储存环（HIRFL-CSR）主环（CsRm）和实验环（CsRe）中束流的纵向运动进行了有针对性的较为详细的研究。首先，作为纵向运动的基础，介绍了加速器物理中纵向运动相关的基础知识，接着推导出同步加速器中束流纵向运动方程，并对纵向运动作了全面的理论分析，在此基础上对CSR内束流的纵向运动进行了计算机模拟研究，得到了高频参数在各过程中变化规律，为高频设备的调试及运行时的参数预置奠定了理论基础。CSRm的主要功能是进行束流的累积加速，从而为实验物理提供高流强、高能量、高品质的重离子束流。由于高频腔频率的范围有限，当HIRFL注入的束流能量较低时，用一次谐波无法对粒子加速。因而针对这一问题，论文对CSRnl内束流的加速过程进行了模拟研究，采用变谐波加速的方式，解决了较低能量下的加速问题。CSRe的主要功能是开展内靶实验和高分辨质量测量。重离子束在CSR工n中加速至中高能引出后剥离成类氢类氦或全裸的重离子注入到CSRe中，此束流具有较高的能量。对于一些特殊的原子物理实验，需要既低能（小于IOMeV／tl）又高离化的重离子束,这就需要在CSSRe中将高离化态的高能重离子束减速到低能，以满足物理实验那要求为因正论文对CSRe内束流的减速过程进行了模拟研究，得到了满足需要的束流。无论对束流加速还是减速都包括连续军的俘获过程，它是影响效率的一个很关键的因素，因而论文还对束流的俘获进行了详细的研究，采用了绝热俘获的方法，提高了加速和减速的效率。论文最后介绍了CSR高频系统、铁氧体及高频腔体测试原理和测试方法，给出了测试结果并进行了分析和讨论。

Mesozoic-Cenozoic tectonic evolution of the Zhuanghai area, Bohai-Bay Basin, east China: the application of balanced cross-sections

The technique of balancing cross-sections, an important method for studying the tectonic history of sedimentary basins, has many applications. It enables one to compile charts for petroleum exploration and development, and growth sections of ancient structures can be restored so that the structural growth history can be studied. In order to study tectonic evolution in the Zhuanghai area of the Bohai-Bay basin, we selected two seismic profiles and compiled two structural growth sections. Based on the two balanced cross-sections, the evolution can be divided into four phases: the Triassic-Middle Jurassic phase, Late Jurassic - Cretaceous phase, Palaeogene extension phase, and Late Palaeogene-to-present phase. The whole area was uplifted during the Triassic-Middle Jurassic phase because of intense extrusion stress related to the Indo-China movement. During the Late Jurassic and Early Cretaceous, intense extension occurred in east China, and the whole area rifted, leading to the deposition of a thick sedimentary sequence. In the Late Cretaceous, the area suffered uplift and compression associated with the sinistral strike slip of the Tanlu fault. In the Palaeogene, a rifting basin developed in the area. Finally, it became stable and was placed in its present position by dextral strike-slip motion. In addition, some problems associated with compiling balanced cross-sections are discussed.

Effect of low-frequency Rossby wave on thermal structure of the upper southwestern tropical Indian Ocean

We investigate the influence of low-frequency Rossby waves on the thermal structure of the upper southwestern tropical Indian Ocean (SWTIO) using Argo profiles, satellite altimetric data, sea surface temperature, wind field data and the theory of linear vertical normal mode decomposition. Our results show that the SWTIO is generally dominated by the first baroclinic mode motion. As strong downwelling Rossby waves reach the SWTIO, the contribution of the second baroclinic mode motion in this region can be increased mainly because of the reduction in the vertical stratification of the upper layer above thermocline, and the enhancement in the vertical stratification of the lower layer under thermocline also contributes to it. The vertical displacement of each isothermal is enlarged and the thermal structure of the upper level is modulated, which is indicative of strong vertical mixing. However, the cold Rossby waves increase the vertical stratification of the upper level, restricting the variability related to the second baroclinic mode. On the other hand, during decaying phase of warm Rossby waves, Ekman upwelling and advection processes associated with the surface cyclonic wind circulation can restrain the downwelling processes, carrying the relatively colder water to the near-surface, which results in an out-of-phase phenomenon between sea surface temperature anomaly (SSTA) and sea surface height anomaly (SSHA) in the SWTIO.

可重构星球探测机器人的空间对接研究

提出了以改装后的位置敏感传感器来引导机器人完成自动对接的方法,分析了具体工作原理。对可重构星球探测机器人在运动模式下完成对接的两种姿态进行了比较,分别用一般方法和改进后的规划方法计算出了对接工作空间,比较结果说明,机器人在运动模式下三角边着地有利于完成自动对接。对工作模式机器人在工作空间内的运动进行了静力学分析,分析结果表明,机器人在工作空间内可以自由运动。用VC和OpenGL搭建的平台对空间对接进行了仿真试验,试验结果验证了对接工作空间计算的正确性和完成空间自动对接的可能性。

基于四自由度并联机构的数控机床研究

介绍一种基于混合型四自由度并联平台机构开发的五坐标并联机床 .由于其独特的机构设计 ,与基于 Stewart平台的并联机床相比 ,X方向的进给运动与运动平台分离 ,改由工作台单独进给 ,因而其工作空间成倍增大 .采用龙门框架结构和滚珠丝杠支承方案使机床获得更高的刚度 .给出了该机床运动学逆解 ,控制系统采用基于 PC的数控系统进行五轴联动控制

基于运动速度的机器人学习控制

为了使机器人跟踪给定的期望轨线，提出了一种新的基于机器人运动重复性的学习控制法．在这种方法中机器人通过重复试验得到期望运动，这种控制法的优点：一是对于在期望运动附近非线性机器人动力学的近似表达式的线性时变机械系统产生期望运动的输入力矩可不由估计机器人动力学的物理参数形成；二是可以适当的选择位置、速度和加速度反馈增益矩阵，从而加快误差收敛速度；三是加入了加速度反馈，减少了速度反馈，减少了重复试验的次数．这是因为在每次试验的初始时刻不存在位置和速度误差，但存在加速度误差．另外，这种控制法的有效性通过ＰＵＭＡ５６２机器人的前三个关节的计算机仿真结果得到验证。

地震力对高架桥梁上轨道车辆的动态分析与安全性研究

The stability and derailment behavior analysis of railway vehicle system has been discussed by many papers in the past. In stability, give first place to consider hunting behavior of vehicle, therefore most of papers was only consider lateral and yaw motion, but vertical motion is the important factor in derailment behavior, and it will be quite effect in stability. We will probe the running stability and derailment behavior of railway vehicle moving on the viaduct in this paper. In this paper, we use Nadal’s formula to get the derailment quotient. In this paper, the railway vehicle is considered to be three subsystems, carbody, bogie and wheelset. There are secondary suspension systems between carbody and bogies, and primary suspension systems connecting bogies and wheelsets. A vehicle with vertical, lateral, roll, and yaw directions motion is considered to derive the mathematical equations. A vehicle with three-dimensional model has 16 degrees of freedom is used to develop the equations of train motion. In this study, results show that the track shift force and derailment factor increase with an increase of ground acceleration. But for the track shift force and derailment factor, the effects of track irregularities and train speed are very small. Key words: earthquake, railway vehicle, viaduct, derailment factor.

东北亚构造-盆地演化及油气资源控制作用

The oil and gas potential of Northeast Asia is enormous, but the degree of exploration is very low in Northeast Asia (the degree is below 3%-10%).The reasons are as follows: First, it is relatively difficult to study the oil and gas bearing basins(OGB), which are of multiple types, in different tectonic settings, with complex geologic frameworks and with long-term geologic evolution. Secondly, because of the non-equilibrium in development of economy and regional market, application of theories and techniques and the research levels in different countries, the conclusions are not conformable, and even contradictory. Thirdly, most of the former researches were limited to one territory or one basin, and lack of systematical and in-depth study on geotectonic evolution, classification of basins, and the evaluation of hydrocarbon resources. In this thesis, integrated study of the regional tectonic feature and basin features of Northeast Asia was done, to understand the basin evolution history and the controlling action on oil and gas. Then, new conclusions are and exploration proposals are as following: 1. Geotectonic evolution in Northeast Asia: The main structural motion system in Paleozoic Era was longitudinal, and in Meso-cenozoic was latitudinal with the Pacific Ocean. The whole evolution history was just the one of pulling-apart, cutting-out, underthrusting and collision of the Central Asia- Mongolia Ocean and the Pacific Ocean. 2. The evolution characteristics of basins in Northeast Asia: mainly developed from longitudinal paste-up, collision and relaxation rifting motion in Paleozoic-Early Mesozoic Era and from underthrust, accretion, and receding of subducted zone of the Pacific Ocean in Late Mesozoic Era-Cenozoic Era. 3. The research in basin classification of Northeast Asia: According to geotectonic system, the basins can be classified into three types: intracratonic, pericratonic and active zone basin. And they can be further classified into 18 different types according to genetic mechanism and dynamic features. 4. The master control factors of oil and gas accumulation in Northeast Asia: high quality cap-rock for craton and pericrationic basin, the effective source rock and high quality cap-rock for Mesozoic rifted basins, intra-arc, fore-arc and back-arc basins. Graded exploration potential of oil and gas for basin in Northeast Asia according to 7 factor, hereby, divided the oil and gas potential of basins into 5 levels. 5. Evaluation of hydrocarbon resources: The difference of resource potential among these basins is huge in Northeast Asia. The evaluation of Mesozoic rifted basin and Pacific Ocean basin showed that the large scale rifted basin and retroarc basin(including backarc marginal sea basin) have great resource potential. 6. The writer believes that the next step should pay more attention to the evaluation of petroleum resource in Far East part of Russia and trace them. On the other hand, according to integrated analysis of oil/gas resource potential and the operation difficulty in this area, suggests that East-Siberia basin, East-Gobi-Tamchag basin, Sakhalin basin, North-Okhotck basin, West-Kamchatka basin could be as cooperation priority basins in future.