Method of Precision Control of 3-D Solid Discretization Based on the Second-Order Osculating Surface

A discretization precision control method based on the second order osculating surface is proposed. The discretization precision of 3 D solid is controlled according to the error between the discrete solid surface and its second order osculating surface. The global maximal error has been gotten after analyzing all the extremums of the error function. It can be used in controlling and optimizing the discretization precision of 3 D solid in computer 3 D modeling and NC milling path generation.

Linear Phase FIR Filter on Measuring 3-D Surface

An optical technology for 3-D surface measurement is set up.The technology,based on a deformed projected grating pattern which carries the 3-D information of the measured object,can automatically and accurately obtain the phase map of a measured object by using a linear-phase FIR filter.In contrast to the 2-D fast Fourier transform technique,it’s more than fast.Only one image pattern is sufficient for measuring.The phase map can be processed without assigning fringe orders and making distinction between a depression and an elevation.Theoretical analysis and experimental result are presented.

ACQUIREMENT AND COMPUTER PROCESSING OF 3-D SURFACE SHAPE DATA

The laser scanning and CCD image-transmitting measurement method and principle on acquiring 3-D curved surface shape data are discussed. Computer processing technique of 3-D curved surface shape(be called“ 3 - D surface shape”for short) data is analysed. This technique in- cludes these concrete methods and principles such as data smoothing, fitting, reconstructing ,elimi- nating and so on. The example and result about computer processing of 3- D surface shape data are given .

A Higher-Efficient Non-Hydrostatic Finite Volume Model for Strong Three-Dimensional Free Surface Flows and Sediment Transport

In order to accurately simulate strong three-dimensional （3-D） free surface flows and sediment transport, the fully 3- D non-hydrostatic pressure models are developed based on the incompressible Navier-Stokes equations and convection-diffusion equation of sediment concentration with the mixing triangle and quadrilateral grids. The governing equations are discretized with the unstructured finite volume method in order to provide conservation properties of mass and momentum, and flexibility with practical application. It is shown that it is first-order accurate on nonuniform plane two-dimensional （2-D） grids and second-order accurate on uniform plane grids. A third-order approximation of the vertical velocity at the top-layer is applied. In such a way, free surface zero stress boundary condition is satisfied maturely, and very few vertical layers are needed to give an accurate solution even for complex discontinuous flow and short wave simulation. The model is applied to four examples to simulate strong 3-D free surface flows and sediment transport where non-hydrostatic pressures have a considerable effect on the velocity field. The newly developed model is verified against analytical solutions with an excellent agreement.

Application of 3-D Geoscience Modeling Technology for the Estimation of Solid Mineral Reserves

Applying new approaches, methods, and technologies for the estimation of reserves can effectively improve the efficiency and accuracy of assessments of solid mineral resources. After analyzing the development of 3-D geoscience modeling technology （3-D GMT）, this paper discusses the application of 3-D GMT for the estimation of solid mineral reserves, emphatically introducing its workflow and two key technologies, 3-D orebody surface modeling, and property modeling. Moreover, the paper analyzes the limitations of traditional methods, such as the section method and geological block method, and points out the advantages of 3-D GMT： building more accurate 3-D orebody models, expressing the internal inhomogeneous attributes of an orebody, reducing the potential for errors in the estimation of reserves, and implementing dynamic estimations of reserves.

Improved treatments for evaluating horizontal magnetic components through the 3-D FDM in E-polarization induction problems

To improve the accuracy of the numerical evaluation through the 3-D finite difference method, the surface boundary conditions are added to modify the old program. The author has tested the new program by making calculations for the model constructed by Wanamaker, et al (1984). The comparison between the numerical results obtained from this paper and those by Wannamaker, et al (1984) indicates that a pronounced improvement is realized in the evaluation of the horizontal magnetic components. Moreover, better calculations for the vertical magnetic components are also obtainable by using the new program.

A New Efficient Finite Volume Modeling of Small Amplitude Free Surface Flows with Unstructured Grid

A staggered finite-volume technique for non-hydrostatic, small amplitude free surface flow governed by the incompressible Navier-Stokes equations is presented there is a proper balance between accuracy and computing time. The advection and horizontal diffusion terms in the momentum equation are discretized by an integral interpolation method on the orthogonal unstructured staggered mesh and, while it has the attractive property of being conservative. The pressure-correction algorithm is employed for the non-hydrostatic pressure in order to achieve second-order temporal accuracy. A conservative scalar transport algorithm is also applied to discretize k - c equations in this model. The eddy viscosity is calculated from the k-c turbulent model. The resulting model is mass and momentum conservative. The model is verified by two examples to simulate unsteady small amplitude free surface flows where non-hydrostatic pressures have a considerable effect on the velocity field, and then applied to simulate the tidal flow in the Bohai Sea.

基于FY-3/VIRR数据的山东省地表温度反演及应用研究

为了检验FY-3/VIRR数据地表温度反演精度,本研究基于FY-3/VIRR数据,选用改进型的Becker和Li分裂窗地表温度反演算法和像元二分法,对山东区域春、夏、秋、冬四季代表月份(4月、7月、10月和1月)分别进行地表温度和植被覆盖度反演,并将反演的地表温度TLS与山东省气象局120个大监站的准同步空气温度Ta和0 cm地温TS进行相关性分析。结果表明:利用FY-3/VIRR数据反演的山东省地表温度与地面实际情况基本吻合,能直观反映山东地区地表温度的空间分布特征,且与植被覆盖度呈明显负相关关系。同时,对于非均匀下垫面,反演的地表温度TLS与空气温度Ta和0 cm地温TS的相关性都不好,不同季节的相关系数差异较大,但(TS-Ta)与(TS-TLS)存在显著线性正相关关系,且相关系数稳定,不同季节的样本判定系数R2都达到0.52以上。

A Lifting Line Theory for a Three-dimensional Hydrofoil

Prandtl’s lifting line theory was generalized to the lifting problem of a three-dimensional hydrofoil in the presence of a free surface. Similar to the classical lifting theory, the singularity distribution method was utilized to solve two-dimensional lifting problems for the hydrofoil beneath the free surface at the air-water interface, and a lifting line theory was developed to correct three-dimensional effects of the hydrofoil with a large aspect ratio. Differing from the classical lifting theory, the main focus was on finding the three-dimensional Green function of the free surface induced by the steady motion of a system of horseshoe vortices under the free surface. Finally, numerical examples were given to show the relationship between the lift coefficient and submergence Froude numbers for 2-D and 3-D hydrofoils. If the submergence Froude number is small free surface effect will be significant registered as the increase of lift coefficient. The validity of these approaches was examined in comparison with the results calculated by other methods.

Fractal Characteristics of Dry Sliding Surfaces Based on 3-D Measurements

D surface morphology measurements of compact graphite irons were used to analyze the frac-tal characteristics of the surfaces to relate the dry sliding surface morphology to the fractal dimension. The measurements show that the fractal dimensions (Df ) of the sliding surfaces vary from1 to 2 and are closely related to the surface morphologies. Increasing depths of grooves or pits increases the Df values. At the same time, increasing densities of the grooves also causes the Df values to increase. The data can be used to discuss relationship between Df and the friction coefficient as well as the wear rate.

复杂三维曲面覆盖算法研究

针对无线传感器网络中三维空间曲面覆盖问题进行研究,建立传感器节点的三维感知模型,考虑到曲面的不规则性,曲面凸点会成为节点感知过程中的障碍物,形成三维空间中特有的三维感知盲区。首先从理论上对简单曲面进行分析,计算出实现有限曲面全覆盖所需的最少节点数,在对三维曲面进行网格划分以及根据三维感知盲区改进适应度函数后,引入差分进化(DE)算法对随机部署在三维空间中的传感器节点的位置坐标进行优化,通过大量仿真实验得出实现目标曲面全覆盖所需的最少的节点数,引入误差率,通过提出的测试准则验证了引用DE算法解决简单三维曲面覆盖问题的有效性。最后将DE算法运用到解决复杂三维曲面覆盖问题中,取得了良好的效果。

SIMULATION OF SEDIMENT DEPOSITION IN A CAVITY WITH FREE SURFACE

Studies of the flow and sediment movement in a cavity with free surface were mostly limited to physical modeling experiments. In this study, the sediment movement is characterized in detail using a 3-D turbulent numerical model. To close the Reynolds equations, the standard k-ε model is employed. The VOF method is adopted to capture the time varying free surface and the porosity method is introduced to deal with the irregular boundary and the varying bed deformation. The computation results agree well with the experimental data in major aspects such as the vertical distribution of the sediment concentration and the deposition topography in the cavity. The comparisons show that this model can well predict the flow structure and the sediment movement and also the river bed deformation in a cavity.

3-D VARIABLE PARAMETER NUMERICAL MODEL FOR EVALUATION OF THE PLANNED EXPLOITABLE GROUNDWATER RESOURCE IN RE-GIONAL UNCONSOLIDATED SEDIMENTS

In order to correctly evaluate the exploitable groundwater resottrce in regional complex, thick Quaternary unconsolidated sediments, the whole Quaternary unconsolidated sediments are considered as a unified hydrogeological unit and a 3-D unsteady groundwater flow numerical model is adopted. Meanwhile, with the consideration of the dynamic changes of the porosity, the hydraulic conductivity and the specific storage with the groundwater level dropping during the exploitation process, an improved composite element seepage matrix adjustment method is applied to solve the unsteady flow problem of free surface. In order to eva- luate the exploitable groundwater resource in Cangzhou, Hebei Province, the hydrogeological conceptual model of Cangzhou is generalized to establish, a 3-D variable parameter numerical model of Cangzhou. Based on the prediction of the present groundwater exploitation, and by adjusting the groundwater exploitation layout, the exploitable groundwater resource is predicted. The model enjoys features like good convergence, good stability and high precision.

The 3-D structure of shear wave in South China and the southward extension of Tanlu fault

By processing the CSND Rayleigh wave data with the matched filter FTAN technique, Rayleigh wave dispersion for southeast China is obtained. The 4°×4°S wave dispersion of the pure path is calculated using random inversion scheme, and 3-D S wave velocity structure is set up. Incorporating the above-mentioned results with wide angle seismic sounding data, we studied structure framework and the extending of faults in this area, which demonstrates that the depth of Moho in South China varies from 30 to 40 km, shallower from west to east. The depth of Moho varies from 25 to 28 km for the offshore. The depth of the asthenosphere in upper mantle varies from 60 to 100 km. The depth difference of layers at the two sides of Tanlu fault is more than 10 km at the south part of the Yangtze River, and the fault extends downward more than 170 km. The fault exceeds the main land at Hainan Island and slips into the southern China Sea. Both Tanlu fault and the huge bend of gravity gradient anomaly are influenced by

Numerical simulation of 3-D water collapse with an obstacle by FEM-level set method

An interface capturing approach based on a level set function for simulating transient two-phase viscous incompressible flows is applied in this paper. A narrow-band signed distance function is adopted to indicate the phase fields and the interface. The multiphase flow is numerically solved by three stages with finite element method （FEM）： （1） solving a two-fluid Navier-Stokes （N-S） equations over the whole domain, （2） transporting the level set function with the obtained velocity field, （3） the level set function correction through a renormalization with continuous penalization which preserves the thickness of the interface. In this paper, the 3-D water colunm collapse with an obstacle is simulated, which yielded good agreement with the experimental data.

A NUMERICAL MODEL FOR 3-D FLOW IN OPEN CHANNELS

A 3-D model based on the Reynolds equations with closed k-ε turbulence model is presented in this paper,which can be used to predict surface water flow in open channels.In- stead of the“rigid lid”approximation,the solution of the free surface equation is implemented in the velocity-pressure iterative procedure on the basis of the conventional SIMPLE method.This model was used to compute the flow in rectangular channels with trenches dredged across the bot- tom.The velocity,eddy viscosity coefficient,turbulent shear stress,turbulent kinetic energy and elevation of the free surface over the trenches dredged in the main channel,can be obtained. The computed results are in good agreement with existing experimentaing data.

2m分辨率遥感影像地表覆盖分类误差研究

以贵州省镇远县焦溪镇为研究区,以资源3号(ZY-3)2m分辨率卫星影像为主要数据源,采用面向对象分类技术提取研究区地表覆盖信息,将提取结果与普莱亚(Pleiades)影像,经目视解译并结合实地验证获取的高精度地表覆盖进行对比,分析ZY-3影像提取地表覆盖各类型的精度误差。研究结果表明:ZY-3影像相对于Pleiades数据提取平均总误差为1.56%,其中旱地和建设用地分类误差相对较大,精度误差分别是3.41%和3.08%。而水体分类误差最小,为0.70%,其余地类水田、乔木林、灌木林、草地、裸地提取误差则分别是1.28%、0.53%、0.86%、1.18%、1.47%。

Profilometry with Grating Projection Based on One-step Phase Shift

An optical technique for 3 D shape measurement is presented. This technique, based on a deformed projected grating pattern which carries 3 D information of the measured object, can automatically and accurately obtain the phase map of a measured object by using one step phase shift algorithm.In comparison with traditional phase shift technique, the technique is much faster, with the equivalent accuracy. Only one frame image is sufficient for measuring. Experimental result of typical object is presented.

A Potential Corrosion Inhibitor for Acid Corrosion of Mild Steel

1-Phenyl-3-methylpyrazol-5-one (HPMP) was evaluated as corrosion inhibitor for mild steel in hydrochloric, nitric and perchloric acid solutions, using weight loss measurements at room temperature. HPMP was found to retard the corrosion rate of mild steel in hydrochloric and nitric acid solutions, while it aided the corrosion of same metal in perchloric acid solution. Corrosion rate decreased linearly with degree of surface coverage, and higher values of half-life were obtained for the coupons coated with HPMP inhibitor. The thicker the film of the HPMP coating on the metal, the more protection it gave to it, giving rise to the increase in inhibition efficiency.

Topographical Parameter Characteristics of Dry Sliding Surfaces of Particle-Reinforced Aluminum Composites

Generally, friction and wear occur on the surface of the materials. It is necessary to investigate the dry sliding friction and wear behavior of surface. In this paper, 3-D topographical parameters were used to investigate the topographical characteristics of dry sliding surfaces for particle-reinforced alu-minum composites on semi-metallic friction material. The experimental results indicate that the surface topography of the particle-reinforced aluminum composites can be divided into two types, the flaking-off pit type and the groove type. The composites whose surface topography is the flaking-off pit type possess superior heat conductivity and bearing area, lower wear rate, and higher friction coefficient than the groove type. Consequently, the flaking-off pit type surface topography is much better than the groove type for particle-reinforced aluminum composites on semi-metallic friction materials in dry sliding.