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Vesic's solutions to cavity expansion that include cylindrical cavity expansion and spherical cavity expansion are introduced. Then cylindrical cavity expansion theory is applied to study compaction effect of pile driving in saturated soil. Based on the results of conventional triaxial tests, a trilinear curve model is used to simulate stress-strain curve of strain-softening materials. Meanwhile, trilinear curves are also used to simulate curves of volumetric strain, minor principal strain and major principal strain. By using elasto-plastic theory, analytical solutions to cylindrical cavity expansion in strain-softening soil are presented. According to the mechanism of statically pressed pile driving, compaction effect of pile tip can be viewed as hemispheric cavity expansion. Therefore spherical cavity expansion theory is applied to obtain the solutions to stress, strain, displacement fields and final pressure. Resistance force of pile tip is calculated to estimate static pressure.

介绍了Vesic关于圆孔扩张问题的解答，其中包括柱形孔扩张问题和球形孔扩张问题，并应用柱形孔扩张理论分析了饱和软土中的沉桩挤土效应问题；在常规三轴试验成果的基础上，采用三折线模型模拟具有应变软化性质的岩土材料的应力应变关系曲线，分析了在应变软化土体中沉桩时桩周土的位移场、应力场和应变场的变化，得到了解析解答；分析了静压桩的沉桩机理，并利用球形孔扩张理论，视桩端处的挤土为半个球形孔的扩张，分析了桩端处土的位移场、应力场和应变场的变化，并根据最终扩张压力计算出沉桩时的桩端阻力，可作为压桩力的估算。

The results show that the ladder-shaped IDT can overcome shortcomings of adding reflection grating or reflector to simulate the internal reflection of IDT in traditional design and simulation,greatly reduce complexity of the simulation with δ function model,imitate its internal reflection with evolutionary structure and then simulate with Matlab.

结果表明，该结构克服了传统设计仿真时需加入反射栅或反射器来模拟叉指换能器内反射的缺点，大大缩减了δ函数模型仿真的繁杂性，通过自身结构的优化来模拟叉指换能器内反射，并运用δ函数对其建模，然后通过Matlab对其仿真。

Recent years as development of the computer and software, it becomes reality using numeric simulation to research grouting in clay. Using the software of PFC2D, the grouting in clay is lucubrated and such achievements are reached: Grouting technologies in existence grouting material and serosity are studied and rational methods are put forward in choosing grouting technology and serosity.(2) Base on numeric simulation biax test a method is explored to simulate clay with PFC2D.(3) A method is explored to simulate grouting using PFC2D.(4) The relation between serosity pressure and diffuseness of grouting in clay with different initial stress is studied.(5) The stress transformation of clay is studied during grouting.(6) The stress distribution is studied under different serosity pressure.(7) The normal stresss and shear stresss at any section are studied.

近年来随着计算技术的发展，使得采用数值模拟的方式研究均质土体中的注浆成为可能，本文则利用离散元程序PFC2D对均质土体中注浆进行了研究，主要做了以下几方面的工作：(1)研究了现有注浆加固技术、注浆材料以及浆液的性质，阐述了合理选择注浆方式以及浆液的方法；(2)采用数值双轴实验，探索了应用离散元模型模拟土体的方法：(3)探索了采用颗粒流程序进行注浆数值模拟的方法途径；(4)研究了在粘土中注浆不同侧向土压力条件下浆液扩散范围与注浆压力规律；(5)研究了注浆过程中不同阶段土体中压应力的变化；(6)研究了不同注浆压力对土体应力分稚的影响：(7)研究了注浆过程中土体中任一截面处正应力与剪应力的对比关系。

Based on the above study, a program is developed which calculate the modeled subgrid stresses, and is applied to simulate the turbulent flow in a plane channel. The computational result is compared with the data extracted form a DNS database, and the agreement is satisfactory. A numbers of physical phenomenon has been reproduced in the simulation, including hairpin vortex and counter-rotating rolls in near wall region, intermittent vortex structure, the maximum of pressure clustering in wall area and the high-speed fluid sweep into the low speed fluid, and the ability of the LES to simulate turbulent flow is well shown.

在对LES技术学习掌握的基础上，编制了亚网格模型的计算程序，在三维平板通道流动的具体计算中应用大涡模拟技术，并与DNS计算结果进行了比较，得到了满意的结果，三维通道中的重要流动现象被很好的预示出来，包括近壁面的发卡涡，对旋涡，间歇猝发涡结构，压力最大值向壁面的倾斜，高速流体对近壁面流体的下扫，卷掠等，显示了大涡模拟技术对湍流流动模拟的能力。

In this paper,a 3-D numerical simulation model is proposed to simulate and analyze the 3-D flow characteristics of natural spawning sites of Acipenser Sinensis by using N-S and k-ε formulas,the volume of fluid method is also used to simulate the two phase flow,and the finite volume method is used to disperse the calculated area.

将水动力学N-S方程、k-ε紊流数值模型与计算水气两相流的方法VOF相结合，采用控制体积法离散计算区域，建立了葛洲坝下游中华鲟产卵场的三维流场模拟模型。

A disturbance to simulate fluctuations at the interface is added to simulate the growth of secondary and third dendrites.

研究了不同过冷度和各向异性系数等相场参数对枝晶生长的影响，最后采用加入非平衡扰动的方式，进行了二次及三次枝晶生长的模拟。

According the experiential formulas of headbox to design the stepped diffuser headbox's geometry parameters. Supposing Paper suspension flow as potential flow and basing on hydrokinetic and computational fluid dynamics theories, we can solve the elliptoid partial differential equations which are followed by the flow functions and the potential functions by finite element method and simulate the flow's speed distribution with pde toolbox of matlab software. The simulate results and the flow analysis have good precision.

按照流浆箱的经验设计公式，设计阶梯扩散式流浆箱的各组件几何参数，以流体动力学、计算流体力学等理论为基础，假定浆流的流动为势流，采用有限元法求解浆流流动时其流函数和速度势函数所符合的椭圆型偏微分方程，应用matlab软件的偏微分方程工具包pde toolbox，模拟出所设计的流浆箱各组件内的浆流的流场流速分布，模拟结果与数值计算流动分析结果吻合。

The core of this model is using solid element to simulate elastoplasticity deformation of faultage and using contact element to simulate the interface of faultage and rock, and so, realizing the problems coupling of elastoplasticity and contact.

模型的核心是以三维实体单元模拟断层或软弱夹层材料弹塑性变形特性，以接触面单元模拟断层或软弱夹层与完整岩石之间交界面的力学特性，即剪切效应和法向提离效应，从而实现了弹塑性问题和接触问题的耦合。

Firstly, the paper, combining the characteristic of synchronous pulse bursts and inhibition with the modified PCNN model, presents a way of finding the foveation points in the images adaptively and effectively, and simulates the human vision system. Secondly, PCNN is extended to PCNNs, based on the properties of information couple and transmission, an algorithm that is used to fuse images of the same target got by several sensors to an image is presented to simulate the human vision system. Thirdly, combining the properties of synchronous pulse bursts, capture, and transmission and competition of waves, the paper presents two ways of classification, one is an algorithm based on the properties of neuron to capture and inhibit to classify the data taking on any complex unlinear distribution robustly, the other is based on the restricted distance and modified of the former to remove the influence of inferior samples in classification; Finally, based on the accumulative difference pictures, and the forming and transmission of PCNN wave, selecting and controlling the direction of autowave by connecting the neighbouring neurons selectively, the paper presents a way to simulate the tracks of moving object and detect the moving direction.

首先结合PCNN的同步脉冲发放和侧抑制特性，提出了基于改进型PCNN的图像凹点检测算法，该算法是一种自适应而有效的图像凹点检测方法，并且较好地仿真了人类视觉系统；然后，结合信息传递和信息耦合特性，将PCNN扩展成PCNNs，提出了一种基于PCNNs的图像融合算法，能够将多个传感器获取的同一目标的图像信息融合到一幅图像中，有效模拟了人类视觉系统；另外，结合PCNN的同步脉冲发放特性、捕获特性和波的传播竞争特性，开拓地将PCNN用于模式分类中，提出了基于耦合神经元点火捕获／抑制特性的分类方法和改进的约束距离下的PCNN分类方法，前者可实现对样本空间中任意复杂分布训练样本的稳健非线性分类，而后者能够消除训练样本中刺点对分类的影响；最后，结合累积差分图像思想、PCNN波的形成与传播特性，通过各神经元之间连接取向来选择与控制自动波的流向，将PCNN用于运动视觉分析中的运动轨迹模拟及运动方向检测。

In order to clearly understand the dynamics mechanism about broad-leaved Korean pine forest and simulate its dynamics mechanically, a simulation model is demanded through which we can simulate the long-term dynamics of BKPF under different pine cones picking intensity and hunting for grey squirrels in different intervals. By considering the effective dispersal of seeds by animals, the human disturbance and the masting behavior of Korean pine, a new gap model integrated seed-bank and regeneration dynamic model, based on the classical gap model, is established.

为了能够充分理解阔叶红松林的动态机制，准确模拟东北阔叶红松林的动态变化，探索出既能够保护好又能够利用好阔叶红松林的新途径，根据阔叶红松林的动态机制，在经典林隙模型的基础上，添加考虑了阔叶红松松林中动物对种子的有效传播、人工采摘干扰以及红松的结实特性，建立了红松种子库及其更新的动念模型更新子模型，使模型更能够反映阔叶红松林中的动态机制。

It is also known as one of the most poisonous naturally occurring substances.

它也被称为一个最自然发生的有毒物质。

The greatest stress is found at the location on the cross section where V is the largest.

最大应力出现在横截面上V为最大的地方。