- 标题
- 摘要
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- 实验方案
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Cloud Masking Technique for High-Resolution Satellite Data: An Artificial Neural Network Classifier Using Spectral & Textural Context
摘要： Cloud masking is a very important application in remote sensing and an essential pre-processing step for any information derivation applications. It helps in estimation of usable portion of the images. Many popular spectral classi?cation techniques rely upon the presence of a short-wave infrared band or bands of even higher wavelength to differentiate between clouds and other land covers. However, these methods are limited to sensors equipped with higher wavelength bands. In this paper, a generic and ef?cient technique is attempted using the Cartosat-2 series (C2S) satellite which is having high-resolution multispectral sensor in the visible and near-infrared bands. The methodology is based on textural features from the available spectral context, and using a feedforward neural network for the classi?cation is proposed. The method was shown to have an overall accuracy of 97.98% for a large manually pre-classi?ed validation dataset with more than 2 million data points. Experimental results and cloud masks generated for various scenes show that the method may be viable as a reasonable cloud masking algorithm for C2S data.
关键词： Cloud masking,Feed forward network,High-resolution satellite data,Image classi?cation,Arti?cial neural network,GLCM texture
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Assessing Predictions Based on Accelerated Stress Tests at Elevated Temperatures for Flexible Cu(In, Ga)Se <sub/>2</sub> Modules
摘要： Spatiotemporal image descriptors are gaining attention in the image research community for better representation of dynamic textures. In this paper, we introduce a dynamic-micro-texture descriptor, i.e., spatiotemporal directional number transitional graph (DNG), which describes both the spatial structure and motion of each local neighborhood by capturing the direction of natural ?ow in the temporal domain. We use the structure of the local neighborhood, given by its principal directions, and compute the transition of such directions between frames. Moreover, we present the statistics of the direction transitions in a transitional graph, which acts as a signature for a given spatiotemporal region in the dynamic texture. Furthermore, we create a sequence descriptor by dividing the spatiotemporal volume into several regions, computing a transitional graph for each of them, and represent the sequence as a set of graphs. Our results validate the robustness of the proposed descriptor in different scenarios for expression recognition and dynamic texture analysis.
关键词： facial expression,transitional graph,spatiotemporal descriptors,Directional number,dynamic texture
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Angular Dependence of Textured Bifacial Silicon Heterojunction Solar Cells for High Latitudes
摘要： Bifacial photovoltaics at high latitudes can achieve up to 25-45% bifacial gain due to high-albedo snow cover and high proportion of diffuse light. We studied the angular performance of bifacial silicon heterojunction solar cells with various textures to understand high-latitude effects on optical losses. For cone and pyramid-patterned designs, efficiency decreases at high angles, primarily due to increased reflectivity, although longer path length through front-surface films also increases UV losses for all surface types. At 80° incidence and 25°C, a <7% reduction in short-circuit current due to change in external quantum efficiency is observed for random pyramid textured surfaces. Simulation is compared to measured external quantum efficiency for a silicon heterojunction cell, and similar trends are observed with increasing angle of incidence. A relative reduction of <1% in short-circuit current is also observed when moving from an air mass of 1.5 to 5 at high angles of incidence. These results will inform future solar heterojunction designs for this application and be applied to refine annual energy yield calculations.
关键词： photovoltaic cells,bifacial photovoltaics,indium-tin-oxide,amorphous silicon,ray tracing,silicon solar cell,texture,angle of incidence,heterojunction cell,air mass
更新于2025-09-23 15:19:57
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Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting
摘要： In recent years, additive manufacturing has attracted attention as a technology that enables control of the crystallographic texture of metallic materials. We achieved successful control of the crystallographic texture of 316L austenitic stainless steel using selective laser melting (SLM). Three distinguished textures were achieved by changing the laser scan speed, namely: the single crystalline-like texture with {001} orientation in the build direction, the crystallographic lamellar texture in which two kinds of grains with {011} and {001} orientations in the build direction are alternately stacked, and polycrystalline with relatively random orientation. The melt pool shape and the solidification behavior (thermal gradient and migration velocity of solid/liquid interface) in a melt pool could be important controlling factors for the evolution of the crystallographic texture under the SLM process.
关键词： anisotropy,crystallographic texture,metal additive manufacturing (AM),selective laser melting (SLM),melt pool
更新于2025-09-23 15:19:57
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Study of the effect of surface laser texture on tribological properties of cemented carbide materials
摘要： Surface texturing has become a potential method to obtain a low friction coefficient under dry/lubricated conditions for different mechanical product surfaces. The mechanism of friction and wear reduction from a micro-texture on the surface of cemented carbide cutting tools was investigated by dry cutting a titanium alloy. Three kinds of micro-textures, namely, line, sinusoidal and rhombic grooves, with different area occupancy rates were produced by a laser on the cemented carbide surface. Experiments and finite element simulation of ABAQUS were used to investigate the tribological characteristics of micro-textured cemented carbide. The results indicated that the line-textured cemented carbide with an area occupancy rate of 10% showed a low friction coefficient of 0.076, which is approximately 34% of the non-textured sample. Few adhesives appeared on the textured surface, while a large number of adhesives were attached to the smooth surface after 30 min of dry friction between the cemented carbide and the titanium alloy balls. Moreover, among the three textures, the line-groove texture has the smallest friction coefficient and a good anti-wear effect. The results show that the existence of a groove texture can effectively reserve the wear debris, reduce the bond wear and weaken the furrow effect.
关键词： titanium alloy,friction and wear,Cemented carbide,machine tool and chip contact zone,surface texture
更新于2025-09-23 15:19:57
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Alignment Tolerance Control of the Micro CPV Array Using Monte Carlo Methods
摘要： Forest degradation is an important issue in global environmental studies, albeit not yet well defined in quantitative terms. The present work addresses the problem, by starting with the assumption that forest spatial structure can provide an indication of the process of forest degradation, this being reflected in the spatial statistics of synthetic aperture radar (SAR) backscatter observations. The capability of characterizing landcover classes, such as intact and degraded forest (DF), is tested by supervised analysis of ENVISAT ASAR and ALOS PALSAR backscatter spatial statistics, provided by wavelet frames. The test is conducted in a closed semideciduous forest in Cameroon, Central Africa. Results showed that wavelet variance scaling signatures, which are measures of the SAR backscatter two-point statistics in the combined space-scale domain, are able to differentiate landcover classes by capturing their spatial distribution. Discrimination between intact and DF was found to be enabled by functional analysis of the wavelet scaling signatures of C-band ENVISAT ASAR data. Analytic parameters, describing the functional form of the scaling signatures when fitted by a third-degree polynomial, resulted in a statistically significant difference between the signatures of intact and DF. The results with ALOS PALSAR, on the other hand, were not significant. The technique sets the stage for promising developments for tracking forest disturbance, especially with the future availability of C-band data provided by ESA Sentinel-1.
关键词： texture,wavelet transform,synthetic aperture radar (SAR),spatial statistics,Degraded forest (DF)
更新于2025-09-23 15:19:57
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Grain orientation and crystallographic texture governed gradient oxidation in laser peening
摘要： This study examined the microstructural/crystallographic textural changes within a laser peened circular spot on Al-Li alloy 2060-T8 and their correlation with gradient oxidation. These changes were looked at the center and edge regions of the circular spot peened at 8 J and 13 J pulse energies. At the pulse energy of 13 J, grain orientation profoundly changed from h0 0 1i (base region) to h1 1 0i (laser spot) with reduced low coincidence site lattice boundaries at the edge of the laser spot. Ideal fibre texture was transformed into strong Cube {0 0 1} h1 0 0i and Goss {0 1 1} h1 0 0i textures respectively at 8 J and 13 J. Dense atomic structured h1 1 0i and h1 1 1i grain orientations and transformed strong Goss texture are observed to promote the oxidation significantly at the edge of laser spot for 13 J. Reasons for gradient oxidation within the laser peened spot were explained from the view point of microstructural/crystallographic textural changes.
关键词： Al-Li alloy,Oxidation,Grain boundaries,Texture,Laser peening
更新于2025-09-23 15:19:57
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Effect of the scanning speed on the microgroove formation regime in nanosecond-pulsed laser scanning ablation of cermet
摘要： As the field of biomedicine continues to grow, so will the need for the quick and efficient manufacture of high-quality micro-textures, such as microfluidic systems, for biomedical functions. The utilization of a nanosecond-pulsed laser enables the realization of an efficient ablation rate in the preparation of a microscaled texture for biomedicine applications. To obtain high-quality ablated features, it is necessary to understand the interaction regime between the pulse laser and cermet. In this work, the effects of the scanning speed on formation mechanisms of microgrooves in pulse laser scanning ablation of cermet are investigated. The relative ablation processes in terms of the particle ejection and the morphology of the ablation traces under various scanning speeds are characterized. In addition, pump-probe shadowgraph imaging is used to observe the ablation dynamics and laser-plume interaction. The results demonstrate that the plume shielding effect, which stems from the intensive pulse energy overlap in the irradiated region, tends to occur at a low scanning speed and results in an intermittent ablation regime. Moreover, there is a critical scanning speed for overcoming the plume shielding effect when other laser parameters are kept constant. To realize an even and continuous ablation process, a high scanning speed that exceeds this critical value should be applied.
关键词： Ablation regime,Pulsed laser scanning ablation,Micro-texture fabrication,Plume shielding effect
更新于2025-09-23 15:19:57
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Selective laser melting of Inconel 718 under high laser power
摘要： Selective laser melting (SLM) process has been lately extensively applied in manufacturing of Nickel-based super alloys, which compared to conventional manufacturing routes offers increased design flexibility and simplification of the manufacturing process. However, in order to make SLM process even more beneficial, its process time has to be reduced. One of the ways to tackle this problem is by tailoring process parameters through application of high laser power and base plate pre-heating. In this paper, a comparative study of optimum SLM fabrication conditions of Inconel 718 superalloy under high laser power and with and without plate pre-heating was conducted. Furthermore, the effect of layer thickness on melt pool characteristics, porosity and hardness were investigated to determine how laser power and pre-heating affect microstructure development.
关键词： Additive manufacturing,Texture,Grain structure,Selective laser melting,Nickel alloy
更新于2025-09-23 15:19:57
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Single-crystalline-like stainless steel 316L with different geometries fabricated by laser powder bed fusion
摘要： In this study, we explored the feasibility of fabricating single-crystalline or single-crystalline-like stainless steel 316L (SS316L) with different geometries (thin struts, cubes, walls and a simulated pump impeller) using laser powder bed fusion (LPBF). The LPBF-fabricated SS316L thin struts possessed a single-crystalline core featuring a ?110? ∥ building direction (BD) crystallographic texture. The cubes, walls and the pump impeller preserved this ?110? ∥ BD texture and also exhibited a well-defined single-crystalline-like {110}?001? Goss texture. Cellular sub-grain structures with their primary dendrite arm spacing (PDAS) values smaller than 1 μm were discovered in all the samples with their growth directions showing a 45° angular deviation from the BD. Nanoscale precipitates and dislocations were also found in the cellular sub-grain structures of the thin struts. The mechanical properties of different geometries (the thin struts, the walls, and the simulated pump impeller) were studied and compared. The anisotropic mechanical responses of the walls and the simulated pump impeller were correlated with their crystallographic textures.
关键词： Single crystal,Geometries,Crystallographic texture,Laser powder bed fusion,Mechanical properties,Stainless steel 316L
更新于2025-09-23 15:19:57