三体问题

The numerical algorithm based on theories of projecting and Laguerre,such as homology,circular points and ω of absolute conic is established,an iterative elimination method is applied to boost the nonlinear problem solving.

通过调和射影及Laguerre定理的推论求解出平面圆环点的共轭虚像，利用平行六面体照片存在的三对圆环点的虚像，构造对无穷远平面绝对二次曲线的像ω的约束，使用辗转相除法求解非线性问题。

The main factors affecting the soil-structure interface behaviors were found experimentally and theoretically, including: 1 the thickness of the interface that is five to six times the average grain size of the soil; 2 the aeolotropy of interface, which is responsible for anisotropic response of the stress-strain response of the interface; 3 two physical states, including crashing and compression of the soil near the structure surface, which govern the stress-strain response of the interface strongly; 4 two shear deformation components due to sliding and constraint of the structure surface relative to the soil respectively, which forms the deformation of the interface; 5 the volumetric strain due to dilatancy, which is found to be composed of a reversible dilatancy component and an irreversible dilatancy component. 4. A unified constitutive model of the interface, based on new elasto-plasticity damage theory, was developed. It was confirmed to be effective for the conditions considering monotonic and cyclic shearing, coupling effect of shear and volumetric strains, evolution of physical state, micro-structure aeolotropy of the soil and the resulting aeolotropy of the interface as well as the three normal boundary conditions stated above. 5. 2D and 3D finite element formulations of the present model were derived and incorporated into the FEM codes. They were applied to the evaluation of practical engineering problems with different typical interfaces between soil and structure. The new model was shown to be reasonable and effective.

确定了粗粒土与结构接触面厚度约为5～6倍的平均粒径，首次揭示了接触面的细观结构异向性以及由此所引起的宏观剪切异向性，发现了在单调和往返剪切荷载作用下土颗粒破碎和剪切压密两种物态变化机制共同支配着接触面力学性质的变化，通过细观分析证实了接触面的变形可分解为一般同时发生的土与结构交界面上的滑移变形以及结构面位移约束范围之内土体本身的剪切变形两部分，观测到接触面受剪时表现出明显的相对法向位移，并可分解为可逆性和不可逆性两个分量；(4)建立了第一个能够统一地描述单调与往返剪切特性、剪应变与体应变耦合特性、细观结构和宏观剪切异向性以及土颗粒破碎等物态变化特性的土与结构接触面弹塑性损伤本构数学模型，并采用多种法向边界条件复杂加载路径的试验成果验证了新模型的合理性和有效性；(5)提出了新模型的二、三维有限元格式并结合实际边值问题进行了应用计算分析，比较了不同接触面本构模型对计算结果的影响，证实了新模型及其有限元格式不仅能够合理地描述土与结构接触面的主要力学特性，还能够较好地反映土体与结构物在接触面处的滑移、脱开等不连续现象。

The Bernese 5.0 software is used to compute the precise orbits of the FORMOSAT-3 and GRACE satellites using the kinematic and reduced-dynamic methods based on zero-differenced GPS phases from these two satellites missions. This study concentrates on the effects of satellite attitude, GPS antenna phase center variation and center of mass.

本论文针对福尔摩沙卫星三号及GRACE卫星姿态、相位及质心影响精密定轨问题分别进行探讨，采用GPS相位观测资料以Bernese 5.0软体进行零次差减动力法及动态法计算轨道。

Design and implement a reliable, high quality, universal hexahedral mesh generation algorithm is the bottle-neck of FEA.

实现可靠的、高品质的、通用的六面体有限元网格自动生成算法是三维有限元仿真领域的瓶颈问题。

In this research, the plane 2D mathematical model under Cartesian coordinate system and the

首先建立了直角坐标系正交网格下的平面二维数学模型及复杂边界适体坐标条件下的三维紊流数学模型，对方程的离散差分格式、控制方程的求解、初始边界条件、动边界处理等问题进行了分析研究，并编制相应的计算程序。

In terms of Cauchy s integral formula of analytical complex function and the three order spline function of complex variable, a general boundary solution method is presented for solving the complex potential field of the flow field around a 2D semi infinite body .

采用复解析函数的Cauchy积分公式和物面复势三阶样条函数逼近，提出了一种求解二维半无限体势流绕流问题复势的通用方法。

About 70% pilots felt masks squeezed their noses and faces, not easy to don or doff or adjust, and they leaked. More than half of the pilots said th...

分析表明，现面罩的舒适性和气密性存在较严重的问题，主要原因是面罩体造型与飞行员面型不符；新面罩的设计必须以我国飞行员的三维面型特征作为造型设计依据，并应轻便无异味。

But there are some elusively essential problems for GIS applied in mine field.

但是目前煤矿领域的地理信息系统有些难以解决的本质问题，主要是对地下三维地质体的数学建模没有很好的解决办法。

In this dissertation the"Penalty"finite element method was employed to compute the velocity of the three-dimensional flow of power-law fluid in a profile die. In order to decrease the needed computer memory and raise the stability of numerical simulation, a set of decoupled methods such as PFEM, pseudo-body force method and transformation of momentum equation to the elliptic equation was developed to establish the general finite element equations to compute the distributions of velocity and viscoelastic stress of the three-dimensional viscoelastic flow of the Phan ThienTanner fluid in a profile die. During numerical simulation of the extrudate swell of the PTT fluid, the flow in the die and out of the die was analyzed separately, which demands less computer memory. The key techniques used in numerical simulation of the three-dimensional extrusion from dies such as decision of boundary conditions, creation of initial velocity field, selection of penalty factor, high Weissenberg number problem , regeneration of the free surface were studied in detail.

中文题名聚合物异型材口模挤出三维流动研究副题名外文题名 Study on three-dimensional flow of polymer melts during the process of profile extrusion from dies 论文作者涂志刚导师柳和生包忠诩教授学科专业材料加工工程研究领域\研究方向学位级别博士学位授予单位南昌大学学位授予日期2001 论文页码总数148页关键词挤出成型聚合物材料挤出口模聚合物异型材馆藏号BSLW /2003 /TQ320 /9 本文建立了求解挤出口模内幂律流体流动速度场的通用三维罚有限元模型；对于非线性粘弹性的Phan Thien-Tanner流体，为了降低模拟计算对计算机硬件的要求，并使模拟计算更加稳定，采用了一种去耦算法，包括罚有限元方法、拟体力方法和动量方程的椭圆类方程转化方法，并建立了求解速度场和粘弹性应力场的总体有限元方程；对于PTT流体的挤出胀大问题，提出了挤出胀大熔体口模内外分离模拟法，这样可以显著降低数值模拟对计算机硬件的要求。

In the third, the ensemble's instrumentation and related issues (such as the types of performance, tessitura, and the gender issue) are discussed.

第三章讨论了乐队编制及一些相关的问题（例如表演形式，合奏的织体特点及性别的问题）。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。