一种从物体表面法线估计高度信息的算法

针对从法向量平面恢复高度信息这个问题,提出了一种从法向量平面恢复高度信息的算法。该算法首先利用一个定义了三维向量的法向量平面构造一个保存表面高度差的平面,然后从像素格状图的某个位置开始向四周相邻的像素累加高度,在遍历所有像素后利用计算好的高度再次从某个位置开始向四周相隔一个像素的位置累加高度,并根据需要的精度进行迭代运算,最后对累加后的高度值求算术平均值,从而得到每个位置最终的高度值。实验结果表明,该算法可以产生精度较高的高度图,并且可以有效地用于视觉效果更好的浮雕贴图技术。

基于表面法线和元胞自动机的自由曲面重构

通过2个阶段实现了从单目灰度图像重构自由曲面的过程:a.对表面法线通过3个约束条件进行逐步调整,光滑约束保证表面法线的光滑过度和可积性,灰度梯度约束确保重构所得的灰度梯度和原始图像的灰度梯度一致,灰度约束保证每点的法线满足光照模型;b.利用一个二维元胞自动机系统,从表面法线重构自由曲面,每个元胞具有自我决策能力,以表面法线为模板,根据自动机系统的自组织行为,实现自由曲面的重构.实验验证了本算法的可行性和准确性,与传统算法相比,重构精度至少提高30%.

利用光度立体法确定的表面法线误差灵敏度分析与校正

利用光度立体法不需要复杂计算就能确定景物内３Ｄ物体的表面方向，但容易产生许多误差．为克服这一问题，文中着重研究与分析几种主要误差，提出新的误差灵敏度分析算法．利用这种新算法，使推导过程变得极为简单并能导出十分严密的表面法线灵敏度计算公式．经试验证明，所得结果与光度立体理论完全一致．

基于三维点云数据的集料颗粒棱角性量化评价

集料颗粒的棱角性是决定沥青混合料路用性能的重要因素。文中首先搭建了基于Gocator 3D智能传感器的集料三维图像采集系统,获取粒径为9.5、13.2和16.0 mm的玄武岩、花岗岩和石灰岩3种集料样本的三维点云数据;然后采用基于Sobel-Feldman卷积和基于集料表面法线的集料颗粒表面棱角性量化方法进行评价,并与现有AIMS梯度棱角评价方法进行了对比。结果表明:基于Sobel-Feldman卷积的集料颗粒表面棱角性量化方法评价集料颗粒棱角性具有更高的准确性;集料越尖锐,集料棱角性指数越大,法线聚类个数越多;集料越圆滑,集料棱角性指数越小,法线聚类个数越少。

基于GLS模型的光照鲁棒性人脸的识别

针对线性子空间模型在处理具有阴影的人脸图像时出现的不足之处,提出了GLS模型,并将其用于不同光照下的人脸识别。按照测试图像与正确模型间距离尽可能小的原则构造了一个确定最优分组数和子空间维数的标准;采用SVD方法和K平均聚类法将像素分组,并确定每个分组的线性子空间模型;计算测试图像到每个GLS模型中所有分组的线性子空间模型的距离之和,进而识别人脸图像。经假设检验统计表明,基于该模型的方法在处理不同光照下的人脸图像时,效果明显优于其他方法。

Surface registration algorithm for rapid detection of surface thermal deformation of paraboloid antennas

In order to obtain and master the surface thermal deformation of paraboloid antennas,a fast iterative closest point( FICP) algorithm based on design coordinate guidance is proposed,which can satisfy the demands of rapid detection for surface thermal deformation. Firstly,the basic principle of the ICP algorithm for registration of a free surface is given,and the shortcomings of the ICP algorithm in the registration of surface are analysed,such as its complex computation,long calculation time,low efficiency,and relatively strict initial registration position. Then an improved FICP algorithm based on design coordinate guidance is proposed. Finally,the FICP algorithm is applied to the fast registration test for the surface thermal deformation of a paraboloid antenna. Results indicate that the approach offers better performance with regard to fast surface registration and the algorithm is more simple,efficient,and easily realized in practical engineering application.

Preparation and characterization of Cu-doped mesoporous CeO_2 for CO oxidation

Mesoporous CeO2 was first synthesized by hydrothermal method,and then used to synthesize different contents of CuO)x/CeO2(x:molar ratio of Cu to Ce) by deposition-precipitation method.These materials were characterized by X-ray diffraction(XRD),N2 adsorption and desorption,H2 temperature programmed reduction(H2-TPR) and O2 temperature programmed desorption(O2-TPD) to study the crystal structure,surface area,and the mechanism of CO oxidation.The results show that,on XRD patterns,no evidence of CuO diffraction peaks is present until Cu loading is increased to 20%.The BET surface area decreases noticeably with the increase of Cu content.Compared with other samples,the better reducibility and activity oxygen species of(CuO)10%/CeO2coincide with its better catalytic activity.

Comparison of wrist motion classification methods using surface electromyogram

The Gaussian mixture model (GMM), k-nearest neighbor (k-NN), quadratic discriminant analysis (QDA), and linear discriminant analysis (LDA) were compared to classify wrist motions using surface electromyogram (EMG). Effect of feature selection in EMG signal processing was also verified by comparing classification accuracy of each feature, and the enhancement of classification accuracy by normalization was confirmed. EMG signals were acquired from two electrodes placed on the forearm of twenty eight healthy subjects and used for recognition of wrist motion. Features were extracted from the obtained EMG signals in the time domain and were applied to classification methods. The difference absolute mean value (DAMV), difference absolute standard deviation value (DASDV), mean absolute value (MAV), root mean square (RMS) were used for composing 16 double features which were combined of two channels. In the classification methods, the highest accuracy of classification showed in the GMM. The most effective combination of classification method and double feature was (MAV, DAMV) of GMM and its classification accuracy was 96.85%. The results of normalization were better than those of non-normalization in GMM, k-NN, and LDA.

Free Surface Flow Generated by Submerged Twin-cylinders in Forward Motion Using a Fully Nonlinear Method

The free surface flow generated by twin-cylinders in forced motion submerged beneath the free surface is studied based on the boundary element method. Two relative locations, namely, horizontal and vertical, are examined for the twin cylinders. In both cases, the twin cylinders are starting from rest and ultimately moving with the same constant speed through an accelerating process. Assuming that the fluid is inviscid and incompressible and the flow to be irrotational, the integral Laplace equation can be discretized based on the boundary element method. Fully-nonlinear boundary conditions are satisfied on the unknown free surface and the moving body surface. The free surface is traced by a Lagrangian technique. Regriding and remeshing are applied, which is crucial to quality of the numerical results. Single circular cylinder and elliptical cylinder are calculated by linear method and fully nonlinear method for accuracy checking and then fully nonlinear method is conducted on the twin cylinder cases, respectively. The generated wave elevation and the resultant force are analysed to discuss the influence of the gap between the two cylinders as well as the water depth. It is found that no matter the kind of distribution, when the moving cylinders are close to each other, they suffer hydrodynamic force with large absolute value in the direction of motion. The trend of force varying with the increase of gap can be clearly seen from numerical analysis. The vertically distributed twin cylinders seem to attract with each other while the horizontally distributed twin cylinders are opposite when they are close to each other.

Preliminary Studies on Predicting the Tropical Indian Ocean Sea Surface Temperature through Combined Statistical Methods and Dynamic ENSO Prediction

The sea surface temperature （SST） in the In- dian Ocean affects the regional climate over the Asian continent mostly through a modulation of the monsoon system. It is still difficult to provide an a priori indication of the seasonal variability over the Indian Ocean. It is widely recognized that the warm and cold events of SST over the tropical Indian Ocean are strongly linked to those of the equatorial eastern Pacific. In this study, a statistical prediction model has been developed to predict the monthly SST over the tropical Indian Ocean. This model is a linear regression model based on the lag relationship between the SST over the tropical Indian Ocean and the Nino3.4 （5°S-5°N, 170°W-120°W） SST Index. The pre- dictor （i.e., Nino3.4 SST Index） has been operationally predicted by a large size ensemble E1 Nifio and the Southern Oscillation （ENSO） forecast system with cou- pled data assimilation （Leefs_CDA）, which achieves a high predictive skill of up to a 24-month lead time for the equatorial eastern Pacific SST. As a result, the prediction skill of the present statistical model over the tropical In- dian Ocean is better than that of persistence prediction for January 1982 through December 2009.

XPS Investigation on Surface and Interface Electronic States of Alq_3/ITO

The surface and interface electronic states of tris (8 hydroxyquinoline) aluminum (Alq 3)/indium tin oxide (ITO) were measured and analyzed by X ray photoelectron spectroscopy (XPS). The results indicated that, in Alq 3 molecule, the binding energy ( E b) of Al atoms is 70.7 eV and 75.1 eV, corresponding to Al(O) and Al(Ⅲ), respectively; The binding energy of C is 285.8 eV, 286.3 eV, and 286.8 eV, corresponding to C of C-C group, C-O, and C-N bond, respectively. N is the main peak locating at 401.0 eV, corresponding to N atom of C-N=C. O atoms mainly bond to H atom, with the binding energy of 533.2 eV. As the sputtering time of Ar + ion beam increases, Al 2p , C 1s , N 1s , O 1s , In 3d 5/2 and Sn 3d 5/2 peaks slightly shift towards lower binding energy, and Al 2p , C 1s and N 1s peaks get weaker, which contributes to diffusing the oxygen, indium and tin in ITO into Alq 3 layer.

Stability and Lubrication Properties of Nano Oxides in Base Oil

The target products were prepared by homogeneous precipitation method using SDS and PEG 800, respectively, as surfactant at a reaction temperature of 95 ℃ for 3 h, followed by calcination at 400 ~C for 3 h. The samples were charac- terized and analyzed by XRD, SEM, FTIR and zeta potential measurements. The products were modified with different sur- factants to improve their dispersion stability, both the amount and the best zeta potential values of which were identified in this work. The surface-modified nano-particles were added at a mass fraction of 1.0%, 2.0%, 3.0%, and 4.0%, respectively, into the base oil. It was showed that the additive in base oil has good oil solubility without detectable corrosion of copper stripe, and had excellent behavior in terms of anti-wear performance and lower friction coefficient.

One-step preparation of vinyl-functionalized material surfaces:a versatile platform for surface modification

A simple approach has been developed to functionalize various substrates, such as gold and polyvinylchloride, with dopamine methacrylamide—a molecule with adhesive properties that mimic those of mussels—to produce a versatile and general platform for subsequent surface modification. With active double bonds on the surface, various polymers, such as poly([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide(PMEDSAH) and poly(N-vinylpyrrolidone)(PVP), can be grafted by conventional radical polymerization. Double bond surface functionalization and subsequent polymer grafting have been verified by static water contact angle, Fourier transform infrared–attenuated total reflectance(FTIR-ATR) spectroscopy and X-ray photoelectron spectroscopy(XPS) measurements. Protein adsorption assays showed that the polymermodified substrates have good protein-resistant properties. Considering the advantages of facility, versatility and substrate- independence, this method should be useful in designing functional interfaces for bioengineering applications.

Chelating agents role on phase formation and surface morphology of single orthorhombic YMn_2O_5 nanorods via modified polyacrylamide gel route

YMn2O5nanorods were synthesized through a modified polyacrylamide gel route.The synthesis strategy in this work is based on a sol-gel process using a polyacrylamide gel method in which oxalic acid,citric acid or tartaric acid is employed as the chelating agent.In the gel routes,oxalic acid was used as a carboxyl chelating agent,while citric acid or tartaric acid was a carboxyl and hydroxyl chelating agent.The as-prepared samples were characterized by means of techniques such as X-ray powder diffraction(XRD)measurement,thermogravimetric analysis(TG),differential scanning calorimetry analysis(DSC),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS),thermal expansion measurement and field-emission scanning electron microscopy(SEM)investigations.It was found that oxalic acid is the best chelating agent with Y(NO3)3·6H2O and Mn(CH3COO)2·4H2O as precursors to prepare a single orthorhombic YMn2O5nanorods at 1000°C.Scanning electron microscope observation shows that the morphology of YMn2O5powders is significantly dependent on the chelating agent.The peaks(single orthorhombic YMn2O5nanorods)at 642,600,573,546,521,493,486,468,448 and 400cm?1were observed from FTIR spectra.The phase,surface morphology and chelation mechanisms of YMn2O5samples have been discussed on the basis of the experimental results.

Wetting transition energy curves for a droplet on a square-post patterned surface

Due to the property of water repellence, biomimetic superhydrophobic surfaces have been widely applied to green technologies, in turn inducing wider and deeper investigations on superhydrophobic surfaces. Theoretical, experimental and numerical studies on wetting transitions have been carried out by researchers, but the mechanism of wetting transitions between Cassie-Baxter state and Wenzel state, which is crucial to develop a stable superhydrophobic surface, is still not fully understood. In this paper, the flee energy curves based on the transition processes are presented and discussed in detail. The exis- tence of energy barriers with or without consideration of the gravity effect, and the irreversibility of wet- ting transition are discussed based on the presented energy curves. The energy curves show that different routes of the Cassie-to-Wenzel transition and the reverse transition are the main reason for the irre- versibility. Numerical simulations are implemented via a phase field lattice Boltzmann method of large density ratio, and the simulation results show good consistency with the theoretical analysis.

Oxidation characteristics of boron particles

The oxidation characteristics of boron particles, boron-A with the diameter of 2.545 μm and boron-B with the diameter of 10.638 μm, at low temperature（1500 K） have been investigated by thermogravimetry（TG） coupled with simultaneous differential scanning calorimetry（DSC）, infrared and mass spectra. A rapid oxidation stage of boron particles, followed by a slow oxidation stage of sintered particles, is found from the TG and DSC curves. The onset temperatures of the oxidation process of boron-A particles are in the range of 806–889 K, which are at least 105 K lower than those of boron-B at the same condition. As the partial pressure of oxygen increases from 5% to 35%, the onset temperature of boron-A or boron-B particles decreases. However, when the partial pressure of oxygen is above 35%, the onset temperature becomes constant, implying a saturation effect of oxygen on the reaction rate. It indicates that the chemical adsorption of oxygen, i.e. chemical reaction, on the particle surface is the rate-limited step at the beginning of the rapid oxidation stage. Therefore, the first-order chemical reaction model is used to simulate the oxidation of boron particles, even that of the sinter. The average activation energies of the particles are 291.3 kJ/mol for boron-A and 338.4 k J/mol for boron-B. While the average activation energies of the sintered particles are 36.35 k J/mol for boron-A and 31.87 kJ/mol for boron-B. The pre-exponential factor of the particles is -10^4, while that of the sinter is 10^-1. The oxidation rate constant of boron is qualitatively mainly affected by the specific surface of the sample and the thickness of the oxide layer.

TRIPLE INTERACTIONS OF CONORMAL WAVES FOR HIGHER ORDER SEMILINEAR HYPERBOLIC EQUMIONS

The interaction of three conormal waves for semi-linear strictly hyperbolic equations of third order is considered. Let Σi, i = 1, 2, 3, be smooth characteristic surfaces for P= Da(D_t￣2 -△) intersecting transversally at the origin. Suppose that the solution u to Pu = f(t, x ,y)D u), ≤2 is conormal to Σi, i = 1, 2, 3, for t < 0. The author uses Bony's second microlocajization techniques and commutator arguments to conclude that the new singularities a short time after the triple interaction lie on the surface of the light cone Γ over the origin plus the surfaces obtained by flow-outs of the lines of intersection Γ ∩ Σi and Σi∩ Σj, i, j = 1, 2, 3.