坝顶自由溢流的数学模型

本文用作者在文献(1)(2)中发展的数值方法,计算了给定流量时坝顶自由溢流问题,文中根据断面比能的概念,确定了缓流向急流过渡的临界断面和临界点的位置,然后采用不同的方法对两种流态的水面进行了调整。计算表明坝面压力分布与自由面位置与实验资料吻合良好。     

堆积体作用下水流水力特性变化试验研究（研究生论坛）

河道中存在堆积体时,水流水力特性将会改变。为分析堆积体不同阻水作用下的作用机理,本文进行了水槽试验。通过对床面比降、堆积体尺度和上游来流条件的控制,研究了不同堆积体尺度条件下的水位变化,分析了堆积体对附加比降的影响,探讨了堆积体附近水流流态的变化规律。结果表明：河道比降相同时,流量越小、堆积体尺度越大,壅水高度和影响范围越大。其它条件相同时,随着河道比降的增大,水流从缓流向急流发展,附加比降值随堆积体尺度的增大而增大;但达到急流条件后,水面附加比降随堆积体尺度增大反而有减小的趋势。     

各向异性弹性力学场论的Hamilton体系

在弹性力学本征化理论的基础上，通过定义正则共轭动量密度，得到了不同变形条件下弹性力学场的Hamilton密度函数，并由此给出了相应的Hamilton正则方程．采用分离变量方法，将弹性动力学解转变为Hamilton空间算子矩阵的本征值问题，对偶变量(模态应变和模态应变率)的全解通过本征解来展开而获得．此外，讨论了不同变形条件下弹性力学场论Hamilton体系的具体应用，得到了弹性小变形、弹性大变形和率相关变形条件下的静力学基本求解方程。     

堆积体作用下水流水力特性变化试验研究

河道中存在堆积体时,水流水力特性将会改变。为分析堆积体不同阻水作用下的作用机理,进行水槽试验。通过对床面比降、堆积体尺度和上游来流条件的控制,研究不同堆积体尺度条件下的水位变化,分析堆积体对附加比降的影响,探讨堆积体附近水流流态的变化规律。结果表明:河道比降相同时,流量越小、堆积体尺度越大,壅水高度和影响范围越大。其他条件相同时,随着河道比降的增大,水流从缓流向急流发展,附加比降值随堆积体尺度的增大而增大;但达到急流条件后,水面附加比降随堆积体尺度增大反而有减小的趋势。     

单层厂房空间工作中屋盖的变形性质

本文包括4项内容:①提出了同时考虑各种因素时厂房屋盖的静力和动力微分方程及其解法,并在此基础上以厂房的实测结果证明:在现有关于屋盖变形性质的各种假定中,以“剪切变压假定”最接近实际情况。②讨论了屋盖转动.屋盖横向局部变形、厂房变形的非线性性质等因素的影响响。③给出了厂房空间刚度参数α和质量刚度参数β的试验公式或经验值。④把厂房作为空间刚架和作为剪切梁计算的结果进行了比较。结果表明,二者计算工作量虽相差百倍,但计算结果却是十分接近的.     

森吉米尔轧机的板形控制

结合武钢硅钢生产实际，从现场检测分析入手，寻找实际轧制过程中森吉米尔轧机的扳形变化规律，建立了多辊系弹性变形仿真模型。通过对各种条件下辊系变形规律的分析，揭示了森吉米尔轧机的板形控制特性.     

基于有限点法的自由面流动的数值模拟

为了准确模拟复杂变形的自由面流动,应用空间粒子法中的有限点法(FPM),即利用移动最小二乘(MLS)法近似流场函数,采用投影法分步求解压力泊松方程,迭代更新流场各粒子的物理信息,数值模拟大变形下的自由面流动问题.数值模拟结果表明:采用有限点法可以较准确地模拟出自由面流动过程中的复杂变形,如迸溅、翻滚、破碎以及入水等现象,与试验结果吻合较好.验证了采用的有限点法对于处理大变形自由面流动问题具有较高的可靠性及较好的灵活性.     

基于MINDLIN解的边坡变形计算方法

通过对开挖荷载的模拟,使得开挖后土体的受力和变形满足弹性半无限体的要求。基于弹性半无限体的MINDLIN应变解,首次推导出基坑边坡变形的理论解,并利用该解研究了不同施工步数条件下基坑边坡侧向变形和竖向变形的规律,并据此提出了边坡加固方法和施工措施。研究结果表明：不同的施工开挖步数条件不但影响边坡的最大侧向变形及其分布,而且还影响边坡的破坏形式;与有关实测数据比较,该方法在计算边坡变形方面合理、实用。     

堆积体对不同比降河流壅水影响研究

河流中大型堆积体的存在,引起河道局部过流面积的减小,从而导致上游壅水,引起上游局部河段水位抬高,在堆积体附近则产生局部较大的附加比降,造成水位的急剧跌落。通过水槽试验研究了不同堆积体尺度条件下的河道壅水影响特性。探讨了不同主河道河道比降(水动力条件)下的最大壅水高度、附加比降的变化规律。结果表明:相对壅水高度随堆积体尺度增加而加大,与主河比降存在正相关关系,但进入急流以后,比降影响将削弱。对试验资料进行参数拟合,给出了不同水动力条件下的相对壅水高度与阻水率间的相互关系。分析了急、缓流条件下堆积体阻水特性在物理机制上的差异。     

二维浮体大幅运动水动力物面非线性时域解

基于时域自由面格林函数，建立了线性自由面条件下计及物体大幅运动瞬时湿表面条件的非线性水动力理论计算模型，重点研究了时域分布源在水线上的特性，指出了传统分布源法在处理浮体与自由面外张斜交的计算失败的原因，并提出了新的时域分布源数值计算模型，对实船计算表明，这种新模型简便有效。     

Free-surface air entrainment in open-channel flows

In hydraulic engineering,free-surface aeration is a natural phenomenon occurring in smooth channel flows.In self-aerated flows,a key aspect that has not yet been well understood is the formation mechanism of free-surface air entrainment.In this research,the process of free-surface entrapped deformation is analyzed theoretically and the critical radius of curvature for air entrainment is obtained,affected by flow mean velocity and depth.When the severity of local free-surface deformation exceeds the critical condition,the entrapped free surface encounters closure in the unstable deformation movement process,resulting in air entrainment.This inference agrees well with observed experimental results that are obtained from the processes of surface entrapped deformation and air entrainment captured by a high-speed camera-based data acquisition system.This agreement indicates that self-aeration occurs in low-velocity open-channel flows.It is also confirmed that free-surface turbulent deformation provides a mechanism for air entrainment.     

气枕式充气膜结构形态与受力分析

为解决气枕式充气膜结构在荷载作用下的变形问题,采用非线性有限元方法对气枕式充气膜结构进行形态分析的基本方法.气枕式充气膜结构的形态分析分为两个阶段:即找形分析与找态分析,由此可得到满足相应要求的几何模型与应力状态.假设密封气枕内质量一定的气体满足理想气体状态方程,在荷载作用下,内压随着体积的变化而变化.给出在一定压力作用下半球状气枕的验证算例并与材料力学中给出的理论解进行比较;基于该方法,另对气枕式充气膜结构在不同外荷载作用下的受力状态进行分析并给出相应的算例,计算结果表明采用理想气体状态方程可以模拟在外部荷载作用下气枕的变形、应力状态以及内压变化情况,且是合理有效的并具有较高的准确性.     

Characters of surface deformation and surface wave in thermal capillary convection

In the field of fluid mechanics, free surface phenomena is one of the most important physical processes. In the present research work, the surface deformation and surface wave caused by temperature difference of sidewalls in a rectangular cavity have been investigated. The horizontal cross-section of the container is 52 mm×42 mm, and there is a silicon oil layer of height 3.5 mm in the experimental cavity. Temperature differ- ence between the two side walls of the cavity is increased gradually, and the flow on the liquid layer will develop from stable convection to un-stable convection. An optical diag- nostic system consisting of a modified Michelson interferometer and image processor has been developed for study of the surface deformation and surface wave of thermal capillary convection. The Fourier transformation method is used to interferometer fringe analysis. The quantitative results of surface deformation and surface wave have been calculated from a serial of the interference fringe patterns. The characters of surface deformation and surface wave have been obtained. They are related with temperature gradient and surface tension. Surface deformation is fluctuant with time, which shows the character of surface wave. The cycle period of the wave is 4.8 s, and the amplitudes are from 0 to 0.55 μm. The phase of the wave near the cool side of the cavity is opposite and correlative to that near the hot side. The present experiment proves that the surface wave of thermal capillary convection exists on liquid free surface, and it is wrapped in surface deformation.     

采用等位函数法求解自由液面流场

文章采用等位函数法求解二维自由液面流动问题。通过导出压力方程，使得连续方程式能自动满足。当压力解出后，即可由运动方程式求解出速度场并以自由跌水流进行了验证。数值结果表明：对于破碎或合并界面的捕捉良好。     

基于扭剪试验的细砂区域长距离流滑机制分析

大量灾害现场发现,即使地面倾角极其平缓（1°~5°）,地表也可能因地震荷载而发生长距离的横向变形。为了解此类砂土变形特性,在改良的空心圆柱扭转剪切仪中采用涌水量概念进行试验,随后采用恒定剪应力静态液化试验,确定排水条件以及小初始静力剪切条件下试样流动的可能性。为突出对比,相同试样被用以进行不排水循环加载试验,观察其行为特征。研究发现：（1）在小初始静态剪应力下可以观察到丰浦砂连续流动的特性;（2）砂土的连续流动特性由初始密实度决定,初始密实度也影响砂土的体积膨胀特性;（3）静态液化试验显示流动砂土试样在涌水机制下可产生流动,而即使样本发生了液化,其在典型的不排水试验中却表现出非流动特性。     

Thermal deformation behavior and microstructure of nuclear austenitic stainless steel

Gleeble-1500D thermal simulation tester was employed in the hot-compression investigation of as-cast nuclear 304 austenitic stainless steel under conditions: deformation temperature 950―1200℃; deformations 30% and 50%; deformation rates 0.01 and 0.1 s?1. The results show that the flow stress decreases with temperature rise under the same strain rate and deformation, that the flow stress increases with deformation under the same temperature and strain rate, and that the flow stress increases with strain rate...     

Microstructural morphology of the semi-solid high carbon steel T12 before and after rheo-rolling

The semi-solid high carbon steel T12 was rolled in a closed box groove under a certain condition by the rheo-rolling equipment, and the microstructural morphology of the semi-solid T12 before and after deformation was investigated by optical microscope to analyze and summarize the microstructure evolution law of T12 deformed in semi-solid state. The experiment results show that the grain shape before deformation of the semi-solid T12 steel displays globule or ellipse by the electromagnetic stirring,the distribution of solid and liquid phases is homogeneous. But the microstructure of semi-solid product after rheo-rolling exhibits macrosegregation that the distribution of liquid and solid phases changes, the liquid phases divorce from the solid phases. In the transverse section, most of the solid phases get together in the center of the specimen, the liquid phases flow to the surface or the edge of the specimen, and the grains occur plastic deformation while reduction increased. In longitudinal section, the middle microstructure of the specimen is more homogeneous than that at the head or tail, the head microstructure is similar to the tail and the size of the grains is not homogeneous.     

Experimental study of thermocapillary convection on a liquid bridge consisting of fluid with low Prandtl number in a floating half-zone

A device of mercury liquid bridge of floating half-zone is designed to experimentally explore thermo-capillary convection and its instability of a low Prandtl number liquid. Noncontacted diagnostic techniques were developed to monitor surface flow and surface deformation. The surface flow and the influence of a growing surface film (or skin) on the flow were observed It is shown that the film is a key factor in changing the behavior associated with the thermocapillary convection. The experiment indicates that the critical Marangoni number should be much higher than that expected by the numerical simulation. The condition and process of surface film growth are discussed. The surface oscillation of the mercury bridge wrapped with "dirt-film" was observed, and the characteristics and the frequency associated with this oscillation are given.     

充填体变形对建筑物影响的有限元极限分析

当前准确确定松散充填体及其周围岩体的变形规律还相当困难，在假定充填江砂被压缩成致密砂岩的极限条件下，运用有限元方法研究了充填体变形对地表建筑物的影响，对于某些情况，可以迅速简捷地做出评价。     

基于SPH方法的自由表面流动模拟

分析了光滑粒子流体动力学(SPH——Smoothed particle hydrodynamics)方法的理论基础及边界条件的处理,并给出了该方法自由表面运动的算例,与商业CFD(Com-putational Fluid Dynamics)软件的VOF(Volume of Fluid)模型的计算结果进行了比较。结果表明,SPH方法模拟复杂自由表面流动具有较好的效果。