Analysis Of Surface Structures Research Articles

A global colour mosaic of Mars from Mars Express HRSC high altitude observations

The ever-changing transparency of the Martian atmosphere hinders the determination of absolute surface colour from spacecraft images. While individual high-resolution images from low orbit reveal numerous colour details of the geology, the colour variation between images caused by scattering off atmospheric dust can easily be of greater magnitude. The construction of contiguous large-scale mosaics has thus required a strategy to suppress the influence of scattering, often a form of high-pass filtering, which limits their ability to convey colour variation information over distances greater than the dimensions of single images. Here we use a dedicated high altitude observation campaign with the Mars Express High Resolution Stereo Camera (HRSC) (Neukum and Jaumann, 2004; Jaumann et al., 2007), applying a novel iterative method to construct a globally self-consistent colour model. We apply the model to colour-reference a high-altitude mosaic incorporating long-range colour variation information. Using only the relative colour information internal to individual images, the influence of absolute image to image colour changes caused by scattering is minimised, while the model enables colour variations across image boundaries to be self-consistently reconstructed. The resulting mosaic shows a level of colour detail comparable to single images, while maintaining continuity of colour features over much greater distances, thereby increasing the utility of HRSC colour images in the tracing and analysis of martian surface structures.

Investigation of torsional and fatigue resistance properties based on triply periodic minimal surfaces (TPMS)

Abstract Triply periodic minimal surfaces (TPMS) are algebraic surfaces found in nature, defined by implicit functions, and exhibit exceptional properties in various fields such as mechanics, computer graphics, and tissue engineering. This study focuses on four common minimal surface structures: Gyroid, Diamond, I-WP, and Schwarz P structures, and presents two methods for converting these surfaces into TPMS cells. These four surface structures are converted into TPMS cells, which are then organized into TPMS cylindrical units for finite element analysis. Through a comparison of the torsional mechanical properties of different minimal surfaces using the finite element method, the stress-strain curves of TPMS were generated. The findings suggest that the Schwarz P cylindrical structure remains within the elastic deformation stage under the same load, with a stress-load curve exhibiting a smaller slope, indicating superior torsional resistance. Additionally, a fatigue strength analysis of various minimal surface structures revealed that, under equivalent load conditions, the fatigue life of the Schwarz P cylindrical structure tends towards infinity.

The role of structural inheritance in the tectonic configuration of the Moroccan Meseta Coastal Block: Insights from morpho-structural and aeromagnetic data

The Coastal Block (CB) of the Western Meseta (Morocco) is located between the Atlantic passive margin and the Middle and High Atlas Mountains. In this contribution, a morpho-structural analysis using topographic data and an aeromagnetic data interpretation have been integrated to map tectonically related structures and to unravel the surface-subsurface faults interaction and their geodynamic implications in the CB. The morpho-structural analysis allowed the structural lineaments mapping through the processing of the topographic and hydrographic data. The application of derivatives operators on the magnetic anomaly map reduced to the pole allowed the assessment of the tectonic framework. The visual integrated analysis of surface and subsurface structures allowed to establish a synthetic structural map of the CB. Several N–S to NNE-SSW, NW-SE and NE-SW oriented fault systems were identified, some of which were confirmed and others were newly outlined. Four geometrically horst and graben type blocks were well distinguished, including the Triassic Basins of Berrechid to the north and of Doukkala to the south separated by the Casablanca Paleozoic block. Meanwhile, the Sahel represents an uplifted zone separating the Doukkala Basin from the continental shelf to the west. Rooted faults bounding these blocks, which are heavily inherited from the pre-Mesozoic tectonic events, record variable reactivation indicators related to the Neogene-Quaternary Atlasic shortening.

Impact of Geometry on the Thermal and Mechanical Properties of Periodic Surface Structures: A Numerical Study

Periodic Surface Structures (PSS) fabricated via Additive Manufacturing (AM) have recently emerged as being appropriate candidates for high-value engineered structures. Among the many PSS designs, gyroid structures have demonstrated merits in mechanical properties and permeability compared to traditional lattice structures. Periodic surface structures are mathematically formulated by geometric factors: surface thickness, sample size, number of surface periods, or unit cells. These elements produce a continuous sur-face with specific topology. Numerical simulations of the effect of modulating these factors on overall thermal and mechanical properties require substantial computational resources and give a quite good qualitative assessment. Cubic P-surface (“Primitive”), D-surface (“Diamond”), and gyroid surface structures of various designs were simulated under load and heat transport using a numerical approach. The influence of geometric factors on thermal and mechanical behavior was determined qualitatively. The results show the impact of the number of cells and surface thickness on both thermal and strength modulus. The paper focuses on thermal and mechanical analysis of periodic surface structures. The study is conducted by solving the stress and heat equations using the Finite Element Method (FEM) and is achieved with the use of our authorial software. Our software module generates periodic surface structures and simulates stress and temperature distribution in it. The stress model is defined by dependence between stress and strain, it got from an experiment, and the correlation of strain and displacement got from geometric conditions. In the paper, we present calculations for three-dimensional systems in which we analyze the stress and temperature distribution depending on the geometric factors. The results presented allow estimation of the behavior of periodic surface structures under loads. It intends to evaluate the possibility of crack occurrence in complex structures based on the performed numerical simulations in future work.

Deformation analysis of surface and bronchial structures in intraoperative pneumothorax using deformable mesh registration

The positions of nodules can change because of intraoperative lung deflation, and the modeling of pneumothorax-associated deformation remains a challenging issue for intraoperative tumor localization. In this study, we introduce spatial and geometric analysis methods for inflated/deflated lungs and discuss heterogeneity in pneumothorax-associated lung deformation. Contrast-enhanced CT images simulating intraoperative conditions were acquired from live Beagle dogs. The images contain the overall shape of the lungs, including all lobes and internal bronchial structures, and were analyzed to provide a statistical deformation model that could be used as prior knowledge to predict pneumothorax. To address the difficulties of mapping pneumothorax CT images with topological changes and CT intensity shifts, we designed deformable mesh registration techniques for mixed data structures including the lobe surfaces and the bronchial centerlines. Three global-to-local registration steps were performed under the constraint that the deformation was spatially continuous and smooth, while matching visible bronchial tree structures as much as possible. The developed framework achieved stable registration with a Hausdorff distance of less than 1 mm and a target registration error of less than 5 mm, and visualized deformation fields that demonstrate per-lobe contractions and rotations with high variability between subjects. The deformation analysis results show that the strain of lung parenchyma was 35% higher than that of bronchi, and that deformation in the deflated lung is heterogeneous.

Three-dimensional tolerance analysis of discrete surface structures based on the torsor cluster model

PurposeThe purpose of this paper is to propose a novel mathematical model to present the three-dimensional tolerance of a discrete surface and to carry out an approach to analyze the tolerance of an assembly with a discrete surface structure. A discrete surface is a special structure of a large surface base with several discrete elements mounted on it, one, which is widely used in complex electromechanical products.Design/methodology/approachThe geometric features of discrete surfaces are separated and characterized by small displacement torsors according to the spatial relationship of discrete elements. The torsor cluster model is established to characterize the integral feature variation of a discrete surface by integrating the torsor model. The influence and accumulation of the assembly tolerance of a discrete surface are determined by statistical tolerance analysis based on the unified Jacobian-Torsor method.FindingsThe effectiveness and superiority of the proposed model in comprehensive tolerance characterization of discrete surfaces are successfully demonstrated by a case study of a phased array antenna. The tolerance is evidently and intuitively computed and expressed based on the torsor cluster model.Research limitations/implicationsThe tolerance analysis method proposed requires much time and high computing performance for the calculation of the statistical simulation.Practical implicationsThe torsor cluster model achieves the three-dimensional tolerance representation of the discrete surface. The tolerance analysis method based on this model predicts the accumulation of the tolerance of components before their physical assembly.Originality/valueThis paper proposes the torsor cluster as a novel mathematical model to interpret the tolerance of a discrete surface.

X-ray spectral analysis of surface structures formed on copper alloys during film fasting

The paper establishes the nature of the redistribution of chemical elements and their concentration in secondary surface structures for the material systems “steel 45XN2MFA-grease-BrOTsS4-4-2.5”, “steel 45XN2MFA-grease-BrOTsS4-4-4”, “steel 45XN2MFA-grease-L-63 ”, tested under the conditions of simulating film starvation when lubricated with 15W40 Lukoil-Super SAE SG/CD engine oil. Since the formula obtained by us includes the Gibbs energy, the self-organization of the structure under consideration naturally also enters. General laws of self-organization are observed when a number of conditions are met: irreversibility, openness (nonequilibrium), nonlinearity, instability (coherence), dissipativity. All these elements were observed and described by us in this work. It is due to self-organization that the distribution of chemical elements carbon and oxygen occurred on the surfaces L63 and BrOF4-4-4. To this effect must be added a decrease in the surface tension of the lubricant.

Multifractal characterization of femtosecond laser-induced herringbone patterns

Analysis of surface structures formed due to femtosecond laser surface ablation is usually done through subjective assessment of the surface images. Here, we analyze the evolution of femtosecond laser-induced surface structures using multifractal analysis. We computed the singularity spectrum to characterize the behavior of laser-induced herringbone patterns. The surface morphology of the ablated surface shows a polarization dependent multifractal nature. The singularity spectrum depicts three distinct morphological phases that sequentially form as a function of the laser pulse number. We objectively characterize the laser-dependent morphological properties of herringbone structures. Multifractal analysis was able to reflect the hierarchy, uniformity, and roughness of the formed structures and their dependence on the pulse number and polarization.

Fast Fourier transport analysis of surface structures fabricated by laser interference lithography

This paper presents an FFT (fast Fourier transform) analytical method for the study of surface structures fabricated by laser interference lithography (LIL). In the work, the FFT analytical method combined with Gaussian fitting is used to determine the periods and pattern distributions of surface structures from frequency spectra. For LIL, the processing parameters of incident and azimuth angles can be obtained corresponding to the period and pattern distribution. This work facilitates the detection of micro- and nano-structures, the analysis of pattern distribution in engineering, and the processing error analysis of LIL.

Optical Microscopy as a probe of the rate limiting transport lifetime in InSb/Al1-xInxSb quantum wells

Recent reports of magnetotransport measurements of InSb/Al1-xInxSb quantum well structures at low temperature (3 K) have shown the need for inclusion of a new scattering mechanism not present in traditional transport lifetime models. Observations and analysis of characteristic surface structures using differential interference contrast DIC (Nomarski) optical imaging have extracted representative average grain feature sizes for this surface structure and shown these features to be the limiting low temperature scattering mechanism. We have subsequently modelled the potential profile of these surface structures using Landauer-Büttiker tunnelling calculations and a combination of a Monte-Carlo simulation and Drude model for mobility. This model matches experimentally measured currents and mobilities at low temperatures, giving a range of possible barrier heights and widths, as well modelling the theoretical trend in mobility with temperature.

Multi-imaging analysis of nascent surface structures generated during femtosecond laser irradiation of silicon in high vacuum

We report a correlative imaging analysis of a crystalline silicon target after irradiation with a low number of 1055 nm, ~ 850 fs laser pulses with several microscopy techniques (e.g., scanning electron microscopy, atomic force microscopy, Raman micro-imaging and confocal optical microscopy). The analysis is carried out on samples irradiated both in high vacuum and at atmospheric pressure conditions, evidencing interesting differences induced by the ambient environment. In high-vacuum conditions, the results evidence the formation of a halo, which is constituted by alternate stripes of amorphous and crystalline silicon, around the nascent ablation crater. In air, such an effect is drastically reduced, due to the significant back-deposition of nanoparticulate material induced by the larger ambient pressure.

Measurement of elastic properties in Brazilian disc test: solution derivation and numerical verification

Mechanical properties of rocks/soils are key inputs in the design and analysis of surface structures (e.g., slope, foundation) and underground excavations (e.g., tunnel, cavern, borehole, and fracture) in earth engineering practice. Brazilian disc test has been extensively used to measure tensile strength for various rocks. In this study, we propose to measure Young’s modulus, Poisson’s ratio and tensile strength in one Brazilian test through making two additional measurements, i.e., two relative displacements using LVDT, or normal strains by pasting two strain gauges, which are perpendicular to each other, at the center of the disc’s side faces. The analytical solutions of the equivalent strains calculated from LVDT measurements or measured directly by strain gauges are derived from elasticity theory. The analytical solutions are verified with measurements in a numerical model. New formulae for calculating Young’s modulus and Poisson’s ratio from two measured strains are provided and their insensitivity to gauge size is illustrated.

Analysis of Different Surface Structures of Hard Metal Guiding Stones in the Honing Process

Honing is a precise abrasive machining process with high standards for the resulting form, dimension, and surface quality. Additionally, honing further improves geometrical tolerances of the machined workpieces, especially when compared to the drilling process. In order to achieve a high adherence it is essential that the honing tool and the workpiece interact accordingly. The following paper will describe the static and dynamic correlations of the process forces of a honing tool equipped with one honing stone and two guiding stones for bores with small diameters (less than 20mm). When working with bores of such small diameters, a direct measurement of the process forces with an integrated sensor is usually difficult to realize. Therefore, a theoretical model will be used to calculate the process forces within the honing tool. Missing coefficients of friction or tangential force coefficients (TFC) within the system will be determined with the help of an external test bench. Moreover, guiding stones made of hard metal with two different types of surfaces will be investigated and then compared with conventional guiding stones. The following measurement results are based on a MATLAB® simulation calculating the forces of the honing and guiding stones.

Density functional theory analysis of surface structures of spinel LiNi0.5Mn1.5O4 cathode materials

First-principle calculation was employed to investigate the surface stability for (100), (110), and (111) low-index facets of LiNi0.5Mn1.5O4 (LNMO) crystallographic structures with a P4332 space group and phase transitions at the surface regions of Ni0.5Mn1.5O4. The calculated surface energies of (100) and (111) facets with Li-terminations are 1.39 and 1.40 eV, respectively, indicating that both these facets of the LNMO are stable according to the calculation results. Defect formation energies and diffusion barriers of Ni and Mn in surface facets of the Ni0.5Mn1.5O4 are much lower than those in the bulk. This suggests that the Ni and Mn ions in the surface regions of the LNMO easily occupy the tetrahedral Li-positions during delithiation process, which supports the experimental results and explains the surface structure changes of the LNMO upon delithiation.

Geostatistical and Statistical Classification of Sea-Ice Properties and Provinces from SAR Data

Recent drastic reductions in the Arctic sea-ice cover have raised an interest in understanding the role of sea ice in the global system as well as pointed out a need to understand the physical processes that lead to such changes. Satellite remote-sensing data provide important information about remote ice areas, and Synthetic Aperture Radar (SAR) data have the advantages of penetration of the omnipresent cloud cover and of high spatial resolution. A challenge addressed in this paper is how to extract information on sea-ice types and sea-ice processes from SAR data. We introduce, validate and apply geostatistical and statistical approaches to automated classification of sea ice from SAR data, to be used as individual tools for mapping sea-ice properties and provinces or in combination. A key concept of the geostatistical classification method is the analysis of spatial surface structures and their anisotropies, more generally, of spatial surface roughness, at variable, intermediate-sized scales. The geostatistical approach utilizes vario parameters extracted from directional vario functions, the parameters can be mapped or combined into feature vectors for classification. The method is flexible with respect to window sizes and parameter types and detects anisotropies. In two applications to RADARSAT and ERS-2 SAR data from the area near Point Barrow, Alaska, it is demonstrated that vario-parameter maps may be utilized to distinguish regions of different sea-ice characteristics in the Beaufort Sea, the Chukchi Sea and in Elson Lagoon. In a third and a fourth case study the analysis is taken further by utilizing multi-parameter feature vectors as inputs for unsupervised and supervised statistical classification. Field measurements and high-resolution aerial observations serve as basis for validation of the geostatistical-statistical classification methods. A combination of supervised classification and vario-parameter mapping yields best results, correctly identifying several sea-ice provinces in the shore-fast ice and the pack ice. Notably, sea ice does not have to be static to be classifiable with respect to spatial structures. In consequence, the geostatistical-statistical classification may be applied to detect changes in ice dynamics, kinematics or environmental changes, such as increased melt ponding, increased snowfall or changes in the equilibrium line.

Analysis of Surface Structures in Ru Nanocatalysts

Analysis of Surface Structures in Ru Nanocatalysts

Physicochemical Analysis of Machine Hammer Peened Surface Structures for Deep Drawing: Determination of the Work of Adhesion and Spreading Pressure of Lubrication to Surface Structure

Increasing demands concerning the performance of tribological systems for metal forming due to ecological restrictions or increased process loads demand the development of innovative tribological solutions. In preliminary works, it could be shown that surface structures on deep drawing tools manufactured by the incremental forming process machine hammer peening (MHP) have the potential to reduce friction. The friction reduction can be observed in strip drawing when comparing different surface structures against a state-of-the-art reference. A subsequently conducted wear analysis showed an adhesive wear on the structures. This leads to the conclusion that the lubricant film breaks due to increased contact pressures. In order to optimize the wetting of the lubricant and to avoid film break-ups, the molecular interactions in terms of the work of adhesion and spreading pressure between lubricant and MHP tool surfaces are investigated from a physicochemical point of view in this research work. The investigation approach is based on the use of the drop shape analysis.

Development of a Novel Surface Elemental Analysis Methodology: X-ray-Aided Noncontact Atomic Force Microscopy (XANAM)

Abstract Scanning probe microscopy (SPM) is widely used for analysis of structures on substrate surfaces. Particularly, scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) enable real-space observations of solid surfaces at the atomic level with high spatial resolution. However, these microscopic measurement methods still involve difficulties in elemental analysis at the nanoscale for general purposes, although several validated solutions have already been proposed for well-defined cases. This brief review explains issues and their resolution, including topics related to the development of chemical analysis methodologies based on STM/NC-AFM, such as inelastic tunneling spectroscopy (IETS)-STM for spectroscopy of individual molecules, STM combined with synchrotron radiation X-ray sources for elemental analysis of surface structures, and force spectroscopy with atom tracking technology, as well as X-ray-aided noncontact atomic force microscopy (XANAM). Particularly, the review describes details of XANAM including recently obtained results on X-ray energy dependence of force spectroscopy and its two-dimensional recording as XANAM imaging, suggesting XANAM offers great potential to contribute to nanoscale investigations of chemical analysis for various purposes.

Computer-automated ABCD versus dermatologists with different degrees of experience in dermoscopy

Dermoscopy is a very useful and non-invasive technique for in vivo observation and preoperative diagnosis of pigmented skin lesions (PSLs) inasmuch as it enables analysis of surface and subsurface structures that are not discernible to the naked eye. The authors used the ABCD rule of dermoscopy to test the accuracy of melanoma diagnosis with respect to a panel of 165 PSLs and the intra- and inter-observer diagnostic agreement obtained between three dermatologists with different degrees of experience, one General Practitioner and a DDA for computer-assisted diagnosis (Nevuscreen(®), Arkè s.a.s., Avezzano, Italy). 165 Pigmented Skin Lesions from 165 patients were selected. Histopathological examination revealed 132 benign melanocytic skin lesions and 33 melanomas. The kappa statistic, sensitivity, specificity and predictive positive and negative values were calculated to measure agreement between all the human observers and in comparison with the automated DDA. Our results revealed poor reproducibility of the semi-quantitative algorithm devised by Stolz et al. independently of observers' experience in dermoscopy. Nevuscreen(®) (Arkè s.a.s., Avezzano, Italy) proved to be 'user friendly' to all observers, thus enabling a more critical evaluation of each lesion and representing a helpful tool for clinicians without significant experience in dermoscopy in improving and achieving more accurate diagnosis of PSLs.

Fabrication and quantitative roughness analysis of hierarchical multiscale polymer surface structures

Nature's functional surfaces are typically hierarchical multiscale structures. There are several techniques for producing such artificial structures on polymers but their mass production is not straightforward. We present here a simple and versatile method for manufacturing hierarchical multiscale polymer surface patterns. The microroughening technique permits the single-step production of multilevel three-dimensional surface architectures in a mechanically durable nickel mold. The molding technique is suitable for area-controlled fabrication of structures with various geometrical shapes on smooth and curved surfaces. The mold structures were transferred to polypropylene surfaces by means of injection molding. The fabricated surface structures were characterized by using a filtered power spectral density method which facilitated a quantitative study of the roughness distributions at different length scales of structure periodicities. Analysis showed that the microroughening technique is an appropriate tool for controlled production of surface roughness at a micro-nanometer scale. Roughness distribution values can be used for predicting surface structure-related properties such as wetting, and the distributions can also be simulated without an experimental preparation process. The work presents a suitable approach for mass production of hierarchical polymer surfaces at different length scales and provides a new route for designing surface structures with tunable wetting properties.