压力测量膜片的形变计算

电容式压力传感器测量膜片的形变,决定了计算压力测量环节中电容值的数学模型.介绍了测量膜片形变方程的建立、推导并对压力测量膜片在不同载荷下的形变特性进行了分析和计算,克服了原有测量膜片形变规律的错误模式.

基于全站扫描仪的真配对点形变计算及点面优化

水电站厂房内设备传统变形监测采用点测量方式,无法反映整体变形特征,而全站扫描仪可快速采集目标表面点云,通过点云处理得到形变量。基于全站扫描仪提出了真配对点的形变计算方法,根据后方交会法设计方案,采集两期点云数据,然后基于真配对点计算形变量并通过点面优化算法减少误差,最后验证了形变计算方法的精度。设计了两个模拟试验验证算法的可行性,通过细绳模拟输电线路弧垂变形和箱体外加锥体模拟壳体鼓包变形,在试验对象上施加外力使其产生形变,并精确测量形变量作为形变参考值。试验结果表明:两个模拟试验的形变计算误差分别为0.146 mm和0.056 mm,精度可达亚毫米级。该形变计算方法能够较好地应用于设施设备变形监测领域。

传动链节距形变量在线检测的新方法

提出了传动链链节形变量在线测量的新方法。用距离传感器采集测量数据,用数字信号处理器进行数据计算,详尽介绍了计算公式的推导过程,对该公式的精度进行验证。从验证的结果可知,本方法不但结构简单易实现,而且测量的精度高(<=0.08MM),可作为传动链检测系统设计与开发的基础。

纳米Si薄膜场发射压力传感器研究

设计研制了一种基于量子隧道效应机制的锥膜一体新结构场发射压力传感器原型器件。测试表明当外加电场为5.6×10~5V/m时,器件有效区域发射电流密度可达53.5A/m^2,由此可看出低维半导体纳米硅技术有效地引入了微电子和硅微机械加工技术相结合的微机电系统,对提高器件发射效率,改善敏感性能效果是明显的。通过三维实体建模与有限元仿真技术,对器件进行了压力形变计算。结果表明,尖锥体的存在,对敏感弹性薄膜在额定压力作用下的最大挠度影响小于0.4％,锥膜一体结构设计是合理的。

基于Virtools平台的森林仿真风效技术研究

森林场景的仿真是对复杂环境仿真中的重要部分。建立具有沉浸感、高逼真度的森林场景,除了高真实感的树木及花卉等植被,同时需考虑风效等影响森林场景逼真度的自然因素。为快速绘制具有真实感的大规模虚拟森林场景,围绕Virtools虚拟现实仿真平台使用树木三维模型进行实时交互的要求,制作插件结合SpeedTree树木软件绘制森林场景制作仿真系统,通过实验室仿真研究常见的风速模型分析比较,提出适合实时植被绘制的森林仿真风速模型,对应用风速模型的森林场景风效进行实验验证。

DETERMINATION OF PRESSURIZING CURVE AND COMPUTER CONTROL OF THICKNESS THINNING FOR SUPERPLASTIC BULGING

This paper proposes the assumption that the flow with viscous friction is the stretch of part of the sheet that lies along the walls of a die during the process of superplastic bulging according to superplastic flow equation and geometrical model of bulging of a sheet into a long trapezoid groove or truncated cone, by introducing the friction-factor P which describes the friction effect on the process. Also, the paper proposes the method of controlling thickness nonuniformity and develops the equipment which for uniform thickness of bulging, is automatically controlled with a computerl it also analyzes the important innuence of lubrication on thickness distribution of bulging materials. By the assumption, the relationship between bulging pressure and time is obtained in bulging of a sheet into the groove and cone, and p-t curve of multi-mould-cavity complicated bulging is discussed based on the analysis of single-mould-cavity bulging characteristics.

Calculation of foundation pit deformation caused by deep excavation considering influence of loading and unloading

A new analytical solution for ground surface settlement induced by deep excavation is proposed based on the elastic half space Melan’s solution,and the analytical model is related to the physical and mechanical properties of soil with the loading and unloading action during excavation process.The change law of earth pressure of the normal consolidation soil after the foundation pit excavation was analyzed,and elastic displacement calculation methods of analytic solution were further established given the influence of excavation and unloading.According to the change of stress state in the excavation process of foundation pit,the planar mechanical analysis model of the foundation excavation problem was established.By combining this model with the physical equations and geometric equations of plane strain problem with consideration of the loading and unloading modulus of soil,constitutive equation of the plane strain problem was also established.The loading and unloading modulus formula was obtained by using the parameter calculation method in Duncan-Chang curve model.The constitutive equation obtained from the model was used to calculate the soil stress state of each point to determine its loading and unloading modulus.Finally,the foundation pit displacement change after excavation was calculated,and thus the soil pressure distribution after retaining structure deformation.The theoretical results calculated by making corresponding programs were applied to engineering practice.By comparing the conventional calculation results with monitoring results,the practicability and feasibility of the calculation model were verified,which should provide a theoretical basis for similar projects.

Numerical study on settlement of high-fill airports in collapsible loess geomaterials:A case study of Lüliang Airport in Shanxi Province,China

Foundation settlement is of great significance for high-fill engineering in collapsible loess areas.To predict the construction settlement of Lüliang Airport located in Shanxi Province,China,a plane strain finite element method considering the linear variation in the modulus,was carried out in this paper based on the results of geotechnical tests.The stress and deformation of four typical sections caused by layered fill are simulated,and then the settlement of the high-fill airport is calculated and analyzed by inputting three sets of parameters.The relative soft parameters of loess geomaterials produce more settlement than the relatively hard parameters.The thicker the filling body is,the greater the settlement is.The filling body constrained by mountains on both sides produces less settlement than the filling body constrained by a mountain on only one side even the filling thickness is almost the same.The settlement caused by the original subbase accounts for 56%−77%of the total settlement,while the fill soils themselves accounts for 23%−44%of the total settlement,which is approximately consistent with the field monitoring results.It provides a good reference for predicting the settlement of similar high-fill engineering.

Theoretical Calculation and Analysis of Slip and Deformation for Concrete Sandwich Panels

Slip and deformation of concrete sandwich panels under uniformly distributed loads is concerned. The effect of slip on the deformation of concrete sandwich panels are studied,and the analytical expressions of slip and deformation for concrete sandwich panels is obtained. These formulae can describe the slip distribution and account for its effect on deformation. In order to restrict the bound of formula, the formula of crack moment is obtained. The results of theoretical calculation are compared with those of tests and finite element methods. The comparison shows that the results of theoretical calculation are in accord with those of tests and finite element methods. So the theoretical calculation can be used to calculate slip and deformation of concrete sandwich panels in practical projects.

Shape Coexistence in Neutron-Deficient At Isotopes in Relativistic Mean-Field Model

The potential energy surfaces are calculated for neutron-deficient At isotopes from A - 190 to 207 in an axially deformed relativistic mean-field approach, using a quadratic constraint scheme for the first time. We find several minima in the potential energy surface for each nucleus, shape-coexistence, and quadratic deform are discussed.

Strain analysis of buried steel pipelines across strike-slip faults

Existing analytical methods of buried steel pipelines subjected to active strike-slip faults depended on a number of simplifications.To study the failure mechanism more accurately,a refined strain analytical methodology was proposed,taking the nonlinear characteristics of soil-pipeline interaction and pipe steel into account.Based on the elastic-beam and beam-on-elastic-foundation theories,the position of pipe potential destruction and the strain and deformation distributions along the pipeline were derived.Compared with existing analytical methods and three-dimensional nonlinear finite element analysis,the maximum axial total strains of pipe from the analytical methodology presented are in good agreement with the finite element results at small and intermediate fault movements and become gradually more conservative at large fault displacements.The position of pipe potential failure and the deformation distribution along the pipeline are fairly consistent with the finite element results.

Symbolic Computation and q-Deformed Function Solutions of （2＋1）-Dimensional Breaking Soliton Equation

In this paper, by using symbolic and algebra computation, Chen and Wang＇s multiple R/ccati equations rational expansion method was further extended. Many double soliton-like and other novel combined forms of exact solutions of the （2＋1）-dimensional Breaking soliton equation are derived by using the extended multiple Riccatl equations expansion method.

Calculations of Invariants for Some 3-manifolds

In this paper,we give some ways of computing invariants of some 3 manifolds,obtained by surgery on circular Hopf link,by using Kauffman polynomial.

Effective grouting area of jointed slope and stress deformation responses by numerical analysis with FLAC^(3D)

To study the grouting reinforcement mechanism in jointed rock slope, first, the theoretical deduction was done to calculate the critical length of slipping if the slope angle is larger than that of joint inclination; Second, the numerical calculation model was founded by FLAG^3D, so as to find the stress and deformation responses of rock mass in the state before and after grouting, the analysis results show that the range between the boundary of critical slipping block and the joint plane that passes the slope toe is the effective grouting area （EGA）. After excavation, large deformation occurs along the joint plane. After grouting, the displacements of rock particles become uniform and continuous, and large deformations along the joint plane are controlled; the dynamic displacement can re- flect the deformation response of slope during excavation in the state before and after grouting, as well as the shear location of potential slip plane. After grouting, the dynamic displacement of each monitoring point reaches the peak value with very few time steps, which indicate that the parameters of the joint plane, such as strength and stiffness, are improved; the stress field becomes uniform. Tensile area reduces gradually; whole stability of the slope and its ability to resist tensile and shear stress are improved greatly.

Deformation and Motion of a Red Blood Cell in a Shear Flow Simulated by a Lattice Boltzmann Model

A lattice Boltzmann model is presented to simulate the deformation and motions of a red blood cell （RBC） in a shear flow. The curvatures of the membrane of a static RBC with different chemical potentiM drops calculated by our model agree with those computed by a shooting method very well. Our simulation results show that in a shear flow, biconcave RBC becomes highly flattened and undergoes tank-treading motion. With intrinsically parallel dynamics, this lattice Boltzmann method is expected to find wide applications to both single and multi-vesicles suspension as well as complex open membranes in various fluid flows for a wide range of Reynolds numbers.

Modeling of ratcheting accumulation of secondary deformation due to stress-controlled high-cyclic loading in granular soils

An objective of this work is to develop a validated computational model that can be used to estimate ratcheting accumulation behavior of granular soils due to high-cyclic loading. An accumulation model was proposed to describe only the envelope of the maximum plastic deformations generated during the cyclic loading process, which can calculate the accumulated deformation by means of relatively large load cycle increments. The concept of volumetric hardening was incorporated into the model and a so-called overstress formulation was employed to describe the evolution of the accumulated volumetric deformation as a state parameter. The model accounted for ratcheting shakedown and accumulation such as a pseudo-yield surface(a shakedown surface) associated with loading inside the current virgin yield surface which was implemented into the well-known modified Cam-clay model. Finally, the model was calibrated using data from the stress-controlled drained cyclic triaxial tests on homogeneous fine grained sands. It is seen that the model can successfully represent important features of the ratcheting accumulation of both volumetric and deviatoric deformation caused by repeated drained loading over a large number of cycles.

Octupole Deformations of Even-Even Rn, Th, and U Nuclei in Relativistic Mean Field Theory

The octupole deformations and other ground state properties of even-even Rn, Th and U isotopes are investigated systematically within the framework of the reflection asymmetric relativistic mean field （RAS-RMF） model. The calculation results reproduce the binding energies and the quadrupole deformations well. The calculation results indicate these nuclei at ground states evolve from neaxly-spherical （N = 130） shape to quadrupole deformation shape with the increase of the neutron number. It is also found that among the Rn isotopes, only^222,224 Rn axe oetupole deformed and the octupole deformations for them are small. However, more nuclei （N ≌ 134 148） in Th and U isotopes are octupole deformed and the octupole deformations for some of them are significant （｜β3｜- 0.1 or even larger）.

Darboux Transformation and Grammian Solutions for Nonisospectral Modified Kadomtsev-Petviashvili Equation with Symbolic Computation

In the present paper, under investigation is a nonisospectral modified Kadomtsev-Petviashvili equation, which is shown to have two Painleve branches through the Painleve analysis. With symbolic computation, two Lax pairs for such an equation are derived by applying the generalized singular manifold method. Furthermore, based on the two obtained Lax pairs, the binary Darboux transformation is constructed and then the N-th-iterated potential transformation formula in the form of Grammian is also presented.

Research on the closure and creep mechanism of circular tunnels

A numerical code called Rock Failure Process Analysis (RFPA2D) was em- ployed to investigate the closure,damage and failure behavior of the horizontal tunnels.In this code the time-dependent deformation was described in terms of evolution of meso- scopic structure,leading to progressive degradation of elastic modulus and failure strength of material.In terms of material degradation,a series of numerical simulations were per- formed to study the convergence and subsequent failure in circular tunnels.The numerical results provide a complete illumination for the closure,damage and failure behavior with different loading conditions.It is shown that the depth and the ratio of far field stresses play an important role in the creep behavior of tunnels.Creep failure is expected to occur in the direction of the smallest far field stress component,which means that rheological failure of tunnels is influenced not only by the rock characteristic around the tunnels but also by the orientation and distribution of far field stress on a global scale.

A fast block-matching algorithm based on variable shape search

Block-matching motion estimation plays an important role in video coding. The simple and efficient fast block-matching algorithm using Variable Shape Search (VSS) proposed in this paper is based on diamond search and hexagon search. The initial big diamond search is designed to fit the directional centre-biased characteristics of the real-world video se- quence, and the directional hexagon search is designed to identify a small region where the best motion vector is expected to locate. Finally, the small diamond search is used to select the best motion vector in the located small region. Experimental results showed that the proposed VSS algorithm can significantly reduce the computational complexity, and provide competitive computational speedup with similar distortion performance as compared with the popular Diamond-based Search (DS) algorithm in the MPEG-4 Simple Profile.