Graphene oxide on the surface of basalt fiber

This paper describes possible procedures for immobilizing two-dimensional graphene oxide flakes on the cylindrical surface of basalt fibers. The samples thus obtained have been characterized by analysis for C, H, and N; X-ray diffraction; scanning electron microscopy; Raman spectroscopy; and atomic force microscopy.     

Autonomic point cloud-based surface reconstruction using SVR

A surface reconstruction framework based on support vector regression (SVR) to generate a three-dimensional (3D) model is proposed in this paper. It can reduce the noise in sampled data as well as repair the holes by handling the missing data during the acquisition phase. SVR is quite efficient for surface reconstruction using parameter tuning and selective data sampling. Automatic parameter tuning of SVR is proposed using two techniques: particle swarm optimization (PSO) and genetic algorithm (GA). Independent component analysis (ICA) is a feature-preserved non-uniform simplification method which is applied to simplify point set by optimal attribute selection. First, under-sample the data, remove the redundancy, reduce the features using ICA and construct the surface using SVR. Both theoretical analysis and experimental results show that the performance of the proposed method yields an average SVR error ≈ 3% on the publicly available datasets. For majority of standard datasets, PSO–SVR is found superior to GA–SVR in convergence speed. Details of the surface are also preserved well which makes it suitable for 3D surface reconstruction.     

Silicon surface reconstruction lost upon cobalt adsorption

We have studied the room-temperature adsorption of cobalt in the range of submonolayer coverages on a reconstructed Si(100)2×1 surface. The measurements were performed by methods of high-resolution (∼140 meV) photoelectron spectroscopy using synchrotron radiation (hν=130 eV). An analysis of changes in the Si 2p line shape in the course of cobalt deposition showed that the metal adsorption leads to the loss of the initial substrate surface reconstruction. The results are interpreted using a model whereby adatoms arriving at the silicon surface are incorporated into the uppermost atomic monolayer, occupying positions between four Si atoms and forming rows parallel to the 〈110〉 directions in the substrate.     

Graphene aerogel induced by ethanol-assisted method for excellent electromagnetic wave absorption

Journal of Materials Science - Graphene aerogels with three-dimensional network structure exhibit excellent electromagnetic (EM) wave attenuation capacity and are often designed as EM-absorbing...     

A new volume warping method for surface reconstruction

Volumetric models of 3D objects have recently been introduced into the reverse engineering process. Due to their efficiency and simplicity, grid-based methods are considered the major technique for reconstructing surfaces from these volumetric models. Yet these methods suffer from a number of inherent drawbacks, resulting from the fact that the imposed Cartesian grid is generally not well adapted to the surface in size or in orientation. To overcome the above obstacles, this paper proposes a new iso-surface extraction method for volumetric objects. The main idea is first to construct a geometrical field induced by the object's shape. This geometrical field represents the natural directions and grid cell size for each point in the domain. Then, the imposed volumetric grid is deformed by the produced geometrical field to approach the object's shape. The iso-surface meshes can be extracted from the resulting adaptive grid by any conventional grid-based contouring technique. These meshes provide a better approximation of the unknown surface and exhibit the anisotropy present in this surface. Since the produced meshes are all quad, Catmull–Clark subdivision surfaces can be directly constructed from them. Moreover, accurate physical models of the reconstructed objects can be produced using rapid prototyping (RP) technology.     

A new volume warping method for surface reconstruction

Volumetric models of 3D objects have recently been introduced into the reverse engineering process. Due to their efficiency and simplicity, grid-based methods are considered the major technique for reconstructing surfaces from these volumetric models. Yet these methods suffer from a number of inherent drawbacks, resulting from the fact that the imposed Cartesian grid is generally not well adapted to the surface in size or in orientation. To overcome the above obstacles, this paper proposes a new iso-surface extraction method for volumetric objects. The main idea is first to construct a geometrical field induced by the object's shape. This geometrical field represents the natural directions and grid cell size for each point in the domain. Then, the imposed volumetric grid is deformed by the produced geometrical field to approach the object's shape. The iso-surface meshes can be extracted from the resulting adaptive grid by any conventional grid-based contouring technique. These meshes provide a better approximation of the unknown surface and exhibit the anisotropy present in this surface. Since the produced meshes are all quad, Catmull-Clark subdivision surfaces can be directly constructed from them. Moreover, accurate physical models of the reconstructed objects can be produced using rapid prototyping (RP) technology.     

Thermal-and field-treatment induced reconstruction of a carbon fiber crystal

A carbon (PAN) fiber crystal was studied in a field electron microscope equipped with a dispersive energy analyzer. Annealing of the emitter crystal at a temperature of 750° C lead to a tenfold decrease in the emission current and to the appearance of an additional low-energy peak (shifted by 0.5 eV from the main peak toward lower energies) in the field electron energy distribution. An increase in the anode voltage restored both the initial emission current and the electron energy distribution.     

Graphene growth on Ni(111) by transformation of a surface carbide

A novel growth mechanism of graphene on Ni(111) has been discovered that occurs at temperatures below 460 °C. At these conditions, a surface-confined nickel-carbide phase coexists with single layer graphene. The graphene grows by in-plane transformation of the carbide along a one-dimensional phase-boundary, which is distinctively different from known growth processes on other transition metals and on Ni above 460 °C, where carbon atoms attach to "free" edges of graphene islands.     

On slippage induced by surface diffusion

The mechanism of surface diffusion is taken at the basis of the phenomenon of slippage of the contact line of a liquid film. With the aid of the condition of continuity of the traction vectors at the solid-liquid interface, we obtained an evolution equation for the velocity of the fluid particles at the wall which shows a marked resemblance with Millikan's equation for the slippage coefficient of gases and reduces, in the limit of small surface diffusivity, to the classical Stokes-Einstein model. The influence of surface roughness is explicitely taken into account and, among other results, cases of absence of slip caused by the attachment of the liquid film to the solid surface and of slippage solely induced by surface roughness are found. Finally, the effect of the surface deformation upon the surface velocity of the fluid particles is examined in some detail.     

Manufacturing‐induced surface contaminations

In the course of classical optics manufacturing glass components are in permanent direct contact with aqueous operating materials. Such contact leads to a certain absorption of water and hydrogenous compounds that may induce severe glass defects. In this contribution, absorption of hydrogen and other contaminants during grinding of glass was observed and qualitatively detected via laser‐induced breakdown spectroscopy. It is shown that hydrogen, calcium, magnesium, and carbon are implanted into the glass surface where the contaminant concentration increases over grinding time or contact time of the glass surface with water and the grinding tool, respectively. The contaminants hydrogen, calcium, and magnesium can be attributed to the water used as lubricant. In contrast, carbon most likely originates from wear debris of the used silicon carbide grinding pads. Several possible mechanisms that lead to such surface contamination of glasses during grinding – diffusion, accumulation in micro cracks as well as the formation of hydrated silica – are finally introduced.     

Double stripe reconstruction of the Pt(111) surface

We have studied the reconstruction of the Pt(111) surface theoretically, using a 2D generalization of the Frenkel-Kontorova model. The parameters in the model are obtained by performingab initio density functional theory calculations. The Pt(111) surface does not reconstruct under normal conditions but experiments have shown that there are two ways to induce the reconstruction: by increasing the temperature, or by depositing adatoms on the surface. The basic motif of this reconstruction is a ‘double stripers with an increased surface density and alternatinghcp andfcc domains, arranged to form a honeycomb pattern with a very large repeat distance of 100–300 Å. In this paper, we have studied the ‘double stripe’ reconstruction of the Pt(111) surface. In agreement with experiment, we find that it is favourable for the surface to reconstruct in the presence of adatoms, but not otherwise.     

Adaptive cross-approximation for surface reconstruction using radial basis functions

The efficient handling of matrices arising in surface interpolation and approximation with radial basis functions (RBF) is considered. To find a data-sparse approximation of the system matrix, the adaptive cross-approximation (ACA) technique is used. The approximation of the matrix requires O (Nlog² N ) units of storage and arithmetic operations, where N is the number of interpolation points. Because basis functions are not explicitly used, the implementation is applicable to a wide class of interpolation kernels. Numerical examples involving generated data and measurements of formed sheet-metal parts are presented.     

Corneal surface reconstruction algorithm that uses Zernike polynomial representation

We developed an algorithm that directly determines Zernike coefficients for the corneal anterior surface derived from the reflection image of a stimulus with pseudorandom encoding. This algorithm does not need to include calculation of corneal height maps. The numerical performance of the algorithm is good. It has the potential of determining corneal shape with submicrometer accuracy in obtaining Zernike coefficients. When applied to real eye measurements the accuracy of the procedure will be limited by the topographer that is used.     

Multiresolution image acquisition and surface reconstruction using active stereo

This paper is concerned with the problem of surface reconstruction from stereo images for large scenes having large depth ranges. The passive stereo paradigm is inadequate for this problem because of the need to aim cameras in different directions and to fixate at different objects. We present an active stereo approach in which the scene is systematically scanned and image acquisition and surface reconstruction are integrated using a four-step process. First, a new fixation point is selected from among the nonfixated, low resolution scene parts of current fixation. Second, a reconfiguration of cameras is initiated for refixation. As reconfiguration progresses, the images of the new fixation point gradually deblur and the accuracy of the stereo estimate of the point improves. In the third step, the improved stereo estimate is used to achieve accurate focus and vergence settings of the cameras for fixation. Finally, focus-based depth estimates are obtained at a grid near the fixation point whose density is determined by the local surface slope. These estimates are fused with those obtained from stereo using maximum likelihood (weighted averaging) and are interpolated to the non-grid points. This research was supported in part by the National Science Foundation under grantiri-89-11942, Army Research Office under grantdaal 03-87-K-0006, and State of Illinois Department of Commerce and Community Affairs under grant 90-103.     

奥氏体不锈钢纤维/铜复合体磁学性能研究

在304奥氏体不锈钢纤维物理性能研究中,发现奥氏体不锈钢在纤维化过程中出现磁性,并且纤维/铜复合体的饱和磁化强度δs大于对应去除铜层的纤维束,而矫顽力呈现相反的规律,该实验结果在反复测试中具有很好的重现性.XRD、SEM和VSM等测试表明铜在界面处向纤维扩散,不锈钢纤维/铜复合体去除铜界面后,部分亚稳相奥氏体恢复到平衡态;是引起不锈钢纤维/铜复合体磁性异常变化的原因.     

Field reconstruction of close-packed atomic complexes at the surface of tungsten

The observation of low-temperature reconstruction of atomic clusters at a close-packed metal face using field ion microscopy is reported. An analysis is made of the configuration of nonclose-packed zigzag atomic chains formed as a result of the decay of clusters. Pis’ma Zh. Tekh. Fiz. 24, 1–6 (December 26, 1998)     

Carburization of iron surface induced by laser heating

The solid state carbon diffusion on an iron surface coated by graphite dag and heated by a continuous wave laser beam has been studied. Experimental values of the diffusion paths have been compared with those calculated by a mathematical model of the thermal cycle induced by laser heating. Case layers have been obtained of about 0.2 mm, with a bainitic structure.     

Corneal surface reconstruction algorithm using Zernike polynomial representation: improvements

Recently Sicam et al. [J. Opt. Soc. Am. A21, 1300 (2004)] presented a new corneal reconstruction algorithm for estimating corneal sag by Zernike polynomials. An equivalent but simpler derivation of the model equations is presented. The algorithm is tested on a sphere, a conic, and a toric. These tests reveal significant height errors that accrue with distance from the corneal apex. Additional postprocessing steps are introduced to circumvent these errors. A consistent and significant reduction in height errors is observed across the test surfaces. Finally, Sicam used the conic p-value p as a measure of algorithm efficacy. Further investigation shows that the finite Zernike representation affected the reported results. The p-value should therefore be used with caution as an efficacy measure.