基于插值函数的海底管道多点提升分析

建立海管点提升的力学模型，用多项式插值得到各种提升状态下的变形和内力.和现有方法相比，该法编程简单，易于实现，能满足工程的计算精度.

Numerical Analyses of Transonic Fluid/Structure interaction in Aircraft Engineering

Through the coupling between aerodynamic and structural governing equations, a fully implicit multiblock aeroelastic solver was developed for transonic fluid/stricture interaction. The Navier-Stokes fluid equations are solved based on LU-SGS (lower-upper symmetric Gauss-Seidel) Time-marching subiteration scheme and HLLEW (Harten-Lax-van Leer-Einfeldt-Wada) spacing discretization scheme and the same subiteration formulation is applied directly to the structural equations of motion in generalized coordinates. Transfinite interpolation (TFI) is used for the grid deformation of blocks neighboring the flexible surfaces. The infinite plate spline (IPS) and the principal of virtual work are utilized for the data transformation between fluid and structure. The developed code was fort validated through the comparison of experimental and computational results for the AGARD 445.6 standard aeroelastic wing. In the subsonic and transonic range, the calculated flutter speeds and frequencies agree well with experimental data, however, in the supersonic range, the present calculation overpredicts the experimental flutter points similar to other computations. Then the flutter character of a complete aircraft configuration is analyzed through the calculation of the change of structural stiffness. Finally, the phenomenon of aileron buzz is simulated for the weakened model of a supersonic transport wing/body model at Mach numbers of 0.98 and l.05. The calculated unsteady flow shows, on the upper surface, the shock wave becomes stronger as the aileron deflects downward, and the flow behaves just contrary on the lower surface of the wing. Corresponding to general theoretical analysis, the flow instability referred to as aileron buzz is induced by a stronger shock alternately moving on the upper and lower surfaces of wing. For the rigid structural model, the flow is stable at all calculated Mach numbers as observed in experiment

A Synoptic View of a Coastal Plain Estuary.

During October, 1972 the Patuxent River Estuary was monitored intensively and synoptically over two tidal cycles to determine the spatial and temporal patterns of various hydrodynamic, chemical and biological features. Forty-one depths at eleven stations along nine transects were sampled simultaneously at hourly intervals for salinity, temperature, dissolved oxygen, chlorohyll a, particulate nitrogen, nitrate, nitrite, total kjeldahl nitrogen, ammonia, particulate carbohydrate, dissolved organic carbon, total hydrolizable phosphorous, dissolved inorganic phosphorous, suspended sediment, particle size distribution, and zooplankton. Tidal velocity was continuously monitored at each depth by recording current meters. Riverine input and meteorological conditions were relatively stable for two weeks preceeding the deployment. This communication describes the calculation of the intrinsic rates of change of the observed variables from their measured distributions in the Estuary. The steady-state, one-dimensional equation of species continuity is employed to separate the advection and tidal dispersion of a hydrodynamically passive substance frbm its intrinsic rate of change at point. A new spatial transform is introduced for the purpose of interpolation and extrapolation of data.The intrinsic rate of change profiles reveal a region of heavy bloom activity in the upper estuary and a secondary bloom near the point in the River that most of the suspended material settles out. The changes in ammonia and nitrates are highly correlated to the productivity patterns. Phosphorous rates are less closely correlated to productivity. The perturbations that the Chalk Point steam electric power plant have on the heat and oxygen balances are easily discernible.

Transonic Aeroelastic Numerical Simulation in Aeronautical Engineering

A lower-upper symmetric Gauss-Seidel (LU-SGS) subiteration scheme is constructed for time-marching of the fluid equations. The Harten-Lax-van Leer-Einfeldt-Wada (HLLEW) scheme is used for the spatial discretization. The same subiteration formulation is applied directly to the structural equations of motion in generalized coordinates. Through subiteration between the fluid and structural equations, a fully implicit aeroelastic solver is obtained for the numerical simulation of fluid/structure interaction. To improve the ability for application to complex configurations, a multiblock grid is used for the flow field calculation and transfinite interpolation (TFI) is employed for the adaptive moving grid deformation. The infinite plate spline (IPS) and the principal of virtual work are utilized for the data transformation between the fluid and structure. The developed code was first validated through the comparison of experimental and computational results for the AGARD 445.6 standard aeroelastic wing. Then, the flutter character of a tail wing with control surface was analyzed. Finally, flutter boundaries of a complex aircraft configuration were predicted.

Numerical-Value Perturbation Method with Application of Solving Convective-Diffusion Integral Equation

The convective--diffusion equation is of primary importance in such fields as fluid dynamics and heat transfer hi the numerical methods solving the convective-diffusion equation, the finite volume method can use conveniently diversified grids (structured and unstructured grids) and is suitable for very complex geometry The disadvantage of FV methods compared to the finite difference method is that FV-methods of order higher than second are more difficult to develop in three-dimensional cases. The second-order central scheme (2cs) offers a good compromise among accuracy, simplicity and efficiency, however, it will produce oscillatory solutions when the grid Reynolds numbers are large and then very fine grids are required to obtain accurate solution. The simplest first-order upwind (IUW) scheme satisfies the convective boundedness criteria, however. Its numerical diffusion is large. The power-law scheme, QMCK and second-order upwind (2UW) schemes are also often used in some commercial codes. Their numerical accurate are roughly consistent with that of ZCS. Therefore, it is meaningful to offer higher-accurate three point FV scheme. In this paper, the numerical-value perturbational method suggested by Zhi Gao is used to develop an upwind and mixed FV scheme using any higher-order interpolation and second-order integration approximations, which is called perturbational finite volume (PFV) scheme. The PFV scheme uses the least nodes similar to the standard three-point schemes, namely, the number of the nodes needed equals to unity plus the face-number of the control volume. For instanc6, in the two-dimensional (2-D) case, only four nodes for the triangle grids and five nodes for the Cartesian grids are utilized, respectively. The PFV scheme is applied on a number of 1-D problems, 2~Dand 3-D flow model equations. Comparing with other standard three-point schemes, The PFV scheme has much smaller numerical diffusion than the first-order upwind (IUW) scheme, its numerical accuracy are also higher than the second-order central scheme (2CS), the power-law scheme (PLS), the QUICK scheme and the second-order upwind(ZUW) scheme.

Computation of flow over a rotating body on unstructured Chimera mesh

Flow around moving boundary is ubiquitous in engineering applications. To increse the efficienly of the algorithm to handle moving boundaries is still a major challenge in Computational Fluid Dynamics (CFD). The Chimera grid method is one type of method to handle moving boundaries. A concept of domain de-composition has been proposed in this paper. In this method, sub-domains are meshed independently and governing equations are also solved separately on them. The Chimera grid method was originally used only on structured (curvilinear) meshes. However, in a problem which involves both moving boundary and complex geometry, the number of sub-domains required in a traditional (structured) Chimera method becomes fairly large. Thus the time required in the interior boundary locating, link-building and data exchanging also increases. The use of unstructured Chimera grid can reduce the time consumption significantly by the reduction of domain(block) number. Generally speaking, unstructured Chimera grid method has not been developed. In this paper, a well-known pressure correction scheme - SIMPLEC is modified and implemented on unstructured Chimera mesh. A new interpolation scheme regarding the pressure correction is proposed to prevent the possible decoupling of pressure. A moving-mesh finite volume approach is implemented in an inertial reference frame. This approach is then used to compute incompressible flow around a rotating circular and elliptic cylinder. These numerical examples demonstrate the capability of the proposed scheme in handling moving boundaries. The numerical results are in good agreement with other experimental and computational data in literature. The method proposed in this paper can be efficiently applied to more challenge cases such as free-falling objects or heavy particles in fluid.

Rayleigh-Taylor不稳定的物理模型和数值模拟

界面不稳定是自然界和工业中流动的普遍现象。本文以Rayleigh-Taylor不稳定性为范例,说明基于物理思想的CFD方法在流动问题研究中的应用。为了确定自由面,以往的Lagrange坐标法、阵面跟踪法在界面发生大变形时都会失效。同时,因流动不稳定从层流发展到湍流要经历若干阶段。因此,如何追踪演化过程的界面变形和如何确定湍流模型是R-T不稳定性研究中的主要困难。本文将溶质浓度差异视为导致介质轻重不同的原因,在不稳定发展过程中发生对流和混合。我们提出采用被动标量的大涡模拟方法来模拟R-T不稳定。鉴于该物理模型考虑了流体粘性和物质扩散的影响,可以自动确定阵面,完整描述不稳定从线性小扰动阶段、经过非线性变形阶段、剪切不稳定阶段到湍流混合阶段,真实重现了现象的物理过程,所以更为优越。通过比较尖钉和气泡阵面前进速度和计算亚格子分量的份

塑性大应变微结构力学

《塑性大应变微结构力学》涉及以下三部分内容：小应变塑性力学；大应变分析；微结构力学分析及其应用。书中既论述有关的数学、力学基础知识，又介绍了学科前沿的研究成果。

第三版前言
第二版前言
第一版前言
第一部分小应变塑性力学
第一章直角坐标系中的向量和张量
1.1直角坐标与单位向量
1.2微积分运算中的公式
1.3坐标变换
1.4Descartes张量张量代数和张量演算
1.5两种张量表示方法的说明
练习
参考文献
第二章微小变形下的应力张量和应变张量
2.1一点上的应力
2.2一点上的应变
2.3平衡方程
2.4协调条件
练习
参考文献
第三章屈服准则和塑性理论
3.1屈服
3.2塑性理论中的公设
3.3流动理论
3.4比例加载下的形变理论
3.5塑性计算的示范
练习
参考文献
第四章塑性力学的发展
4.1基于塑性耗散能的本构形式
4.2近似蠕变分析-比应力-应变曲线方法
4.3机动硬化模型
4.4角点理论
4.5相关的和非相关的流动法则
参考文献
第二部分大应变分析
第五章一般坐标系中的张量及其各类时间导数
5.1一般坐标系中的基量
5.2坐标变换张量及协变导数
5.3坐标系统
5.4变换时间导数的Oldroyd方程
练习
参考文献
第六章应变张量应力张量和它们的变化率
6.1应变张量
6.2各类应变率张量
6.3应力张量
6.4应力张量的各种变化率
练习
参考文献
第七章在有限变形下平衡的变分原理及分叉理论
7.1固体的弹性超弹性和亚弹性
7.2变分原理及应力与应变的共轭关系
7.3平衡的稳定性和分叉准则
7.4Lagrange和逐级更新Lagrange系统中平衡和分叉的增量型变分原理
7.5大应变本构方程及数值计算步骤
练习
参考文献
第三部分微结构力学及其应用
第八章确定材料的总体力学行为与其微结构参数之间的
关系
8.1"自洽"原则
8.2塑性力学中的内变量
8.3用计算机模拟方法确定内变量
练习
参考文献
第九章空洞的分析
9.1空洞的萌生和扩展的试验
9.2单级空洞效应的理论模型
9.3两级空洞效应的理论模型
9.4空洞化材料的宏观响应与力学和几何微观参数之间的关系
9.5基于微结构研究成果所设立的连续介质本构模型和失效准则
9.6空洞化损伤的三维分析及探讨应变加载模态影响的方法
9.7应变加载模态对空洞化损伤材料力学性能的影响及其与次级空洞间的交互作用
参考文献
第十章剪切带状分叉
10.1材料分叉的原理
10.2平面应变条件下的局部化剪切带
10.3材料非均匀性或初始缺陷的影响
10.4轴对称加载下的局部化轴对称剪切带
10.5局部化曲线剪切带
10.6局部化剪切带的三维解
10.7平面应变条件下扩散型剪切带的一维分析
10.8平面应变条件下扩散型剪切带的二维分析
参考文献
第十一章空洞和分叉的分析在金属板材成型中应用
11.1平面应力模型中空洞扩展效应
11.2分叉分析
11.3双相钢薄板成型实验与数值分析的比较
11.4单向加载条件下平板的材料分叉
参考文献
第十二章韧性断裂
12.1塑性可膨胀本构方程的论证
12.2确定本构参数
12.3韧性断裂的计算
12.4韧姓断裂的实验
参考文献
附录A弹性力学基本方程
A.1广义Hooke定律
A.2平面问题
A.3轴对称问题
A.4弹性力学解的可叠加性和惟一性
A.5St.Venant原理
练习
参考文献
附录B弹性力学变分原理及解法
B.1应变能和应变余能
B.2虚位移和虚功原理
B.3最小势能原理
B.4最小余能原理
B.5两个变分原理的关系
B.6双变量广义变分原理
B.7基于变分原理的直接解法
练习
参考文献

塑性力学和细观力学文集

Nassau grouper (Epinephelus striatus) spawning aggregations: hydroacoustic surveys and geostatistical analysis

With the near extinction of many spawning aggregations of large grouper and snapper throughout the Caribbean, Gulf of Mexico, and tropical Atlantic, we need to provide baselines for their conservation. Thus, there is a critical need to develop techniques for rapidly assessing the remaining known (and unknown) aggregations. To this end we used mobile hydroacoustic surveys to estimate the density, spatial extent, and total abundance of a Nassau grouper spawning aggregation at Little Cayman Island, Cayman Islands, BWI. Hydroacoustic estimates of abundance, density, and spatial extent were similar on two sampling occasions. The location and approximate spatial extent of the Nassau grouper spawning aggregation near the shelf-break was corroborated by diver visual observations. Hydroacoustic density estimates were, overall, three-times higher than the average density observed by divers; however, we note that in some instances diver-estimated densities in localized areas were similar to hydroacoustic density estimates. The resolution of the hydroacoustic transects and geostatistical interpolation may have resulted in over-estimates in fish abundance, but still provided reasonable estimates of total spatial extent of the aggregation. Limitations in bottom time for scuba and visibility resulted in poor coverage of the entire Nassau grouper aggregation and low estimates of abundance when compared to hydroacoustic estimates. Although the majority of fish in the aggregation were well off bottom, fish that were sometimes in close proximity to the seafloor were not detected by the hydroacoustic survey. We conclude that diver observations of fish spawning aggregations are critical to interpretations of hydroacoustic surveys, and that hydroacoustic surveys provide a more accurate estimate of overall fish abundance and spatial extent than diver observations. Thus, hydroacoustics is an emerging technology that, when coupled with diver observations, provides a comprehensive survey method for monitoring spawning aggregations of fish.

Analytical efficiency evaluation of a network mobility management protocol for Intelligent Transportation Systems

One of the major concerns in an Intelligent Transportation System (ITS) scenario, such as that which may be found on a long-distance train service, is the provision of efficient communication services, satisfying users' expectations, and fulfilling even highly demanding application requirements, such as safety-oriented services. In an ITS scenario, it is common to have a significant amount of onboard devices that comprise a cluster of nodes (a mobile network) that demand connectivity to the outside networks. This demand has to be satisfied without service disruption. Consequently, the mobility of the mobile network has to be managed. Due to the nature of mobile networks, efficient and lightweight protocols are desired in the ITS context to ensure adequate service performance. However, the security is also a key factor in this scenario. Since the management of the mobility is essential for providing communications, the protocol for managing this mobility has to be protected. Furthermore, there are safety-oriented services in this scenario, so user application data should also be protected. Nevertheless, providing security is expensive in terms of efficiency. Based on this considerations, we have developed a solution for managing the network mobility for ITS scenarios: the NeMHIP protocol. This approach provides a secure management of network mobility in an efficient manner. In this article, we present this protocol and the strategy developed to maintain its security and efficiency in satisfactory levels. We also present the developed analytical models to analyze quantitatively the efficiency of the protocol. More specifically, we have developed models for assessing it in terms of signaling cost, which demonstrates that NeMHIP generates up to 73.47% less signaling compared to other relevant approaches. Therefore, the results obtained demonstrate that NeMHIP is the most efficient and secure solution for providing communications in mobile network scenarios such as in an ITS context.

线性压电材料的有限元分析

本文利用线性压电学理论，编制了线性压电材料四结点等参有限元程序，进行了校核，并对PZT-5A材料压电智能元件和压电材料标准断裂试进行了计算，计算包括：①采用实际工程应用的压电智能元件尺寸，计算了元件的压电响应；并针对元件内部电极尖端区域容易引起破坏的现象，计算了该区域的奇异应力、应变场及电场。②计算了加力和加电两种情况下压电材料标准断裂试件应力强度因子影响系数F_I和电位移强度因子影响系数F_D。裂纹面边界条件采用D-P条件，试件包括紧凑拉伸标准试件和三点弯曲标准试件。③应用Lagrange乘子法将Parton裂纹边界条件加于有限元程序中，计算了上述两种标准断裂试件的F_I和F_D，计算结果与采用D-P裂纹边界条件的计算结果有很大差异。

Large-eddy simulation of flows past a flapping airfoil using immersed boundary method

The numerical simulation of flows past flapping foils at moderate Reynolds numbers presents two challenges to computational fluid dynamics: turbulent flows and moving boundaries. The direct forcing immersed boundary (IB) method has been devel- oped to simulate laminar flows. However, its performance in simulating turbulent flows and transitional flows with moving boundaries has not been fully evaluated. In the present work, we use the IB method to simulate fully developed turbulent channel flows and transitional flows past a stationary/plunging SD7003 airfoil. To suppress the non-physical force oscillations in the plunging case, we use the smoothed discrete delta function for interpolation in the IB method. The results of the present work demonstrate that the IB method can be used to simulate turbulent flows and transitional flows with moving boundaries.

An Integrated Evolutionary Algorithm for Expensive Global Optimization

We propose an integrated algorithm named low dimensional simplex evolution extension (LDSEE) for expensive global optimization in which only a very limited number of function evaluations is allowed. The new algorithm accelerates an existing global optimization, low dimensional simplex evolution (LDSE), by using radial basis function (RBF) interpolation and tabu search. Different from other expensive global optimization methods, LDSEE integrates the RBF interpolation and tabu search with the LDSE algorithm rather than just calling existing global optimization algorithms as subroutines. As a result, it can keep a good balance between the model approximation and the global search. Meanwhile it is self-contained. It does not rely on other GO algorithms and is very easy to use. Numerical results show that it is a competitive alternative for expensive global optimization.

New variational principles for systems of partial differential equations

The question of finding variational principles for coupled systems of first order partial differential equations is considered. Using a potential representation for solutions of the first order system a higher order system is obtained. Existence of a variational principle follows if the original system can be transformed to a self-adjoint higher order system. Existence of variational principles for all linear wave equations with constant coefficients having real dispersion relations is established. The method of adjoining some of the equations of the original system to a suitable Lagrangian function by the method of Lagrange multipliers is used to construct new variational principles for a class of linear systems. The equations used as side conditions must satisfy highly-restrictive integrability conditions. In the more difficult nonlinear case the system of two equations in two independent variables can be analyzed completely. For systems determined by two conservation laws the side condition must be a conservation law in addition to satisfying the integrability conditions.