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Impact of Resolution and Texture of Laser Scanning Generated Three‐Dimensional Models on Landmark Identification
摘要： The aim of the study was to determine the impact of the resolution and texture of 3D models created through laser scanning on the measurement error (ME) of craniometric landmarks. Ten skulls were scanned at five different resolutions, and the generated 3D models were exported with and without texture. The 3D coordinates of 28 landmarks were derived. Each landmark was picked five times by one observer. The ME of a definite landmark was calculated as an average of distances between the repeated placements of the landmark by the observer and the landmark centroid. One-way ANOVA was applied for detection of significant differences in the MEs between and within landmark types recorded at different resolutions. The MEs of landmark types in textured and non-textured models were compared by a paired test. Twelve linear measurements were calculated as interlandmark distances and their values obtained on the models of different resolution were compared. The Frankfurt horizontal plane was constructed for each model and its deviation was calculated at different resolutions. Scan resolution impacted MEs of Type 1 and 2 landmarks, but not the precision level of Type 3 landmarks. Texture most influenced the precise identification of Type 1 landmarks. The interlandmark distances between Type 2 landmarks were most consistent in their values, those between Type 1 landmarks showed deviations in low-resolution models, and distances between Type 3 landmarks demonstrated various patterns of transition of the values throughout the resolutions. Altogether, the use of textured high-resolution models would be preferable in morphometric studies.
关键词： Laser scanning,3D model,craniometric landmarks,texture,measurement error,resolution
更新于2025-09-19 17:13:59
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The influence of the pyramidal texture uniformity and process optimization on monocrystalline silicon solar cells
摘要： To improve the photoelectric conversion efficiency of monocrystalline silicon solar cells, the influence of the pyramidal texture uniformity on the defects in the monocrystalline silicon cells was analyzed by simulation, and the uniformity of the pyramidal texture was quantitatively characterized with the uniformity coefficient. The texturing process parameters were optimized by fitting and optimizing the uniformity coefficient. In the experiments herein, four groups of textured monocrystalline silicon wafers were obtained by treating them with a 1.2% sodium hydroxide (NaOH) solution for four different times. The uniformity coefficient of each monocrystalline silicon wafer group was obtained. By fitting the uniformity coefficient, we obtained the texturing process parameters corresponding to the maximum uniformity coefficient. The experimental results show that the optimized monocrystalline silicon cell achieved a pyramidal texture with a maximum uniformity coefficient. In addition, the reflectivity of the monocrystalline silicon cell reached a minimum value, and the photoelectric conversion efficiency reached a maximum value. The uniformity coefficient can not only effectively quantify the uniformity of the pyramidal texture but also effectively optimize the texturing process parameters to improve the photoelectric conversion efficiency of monocrystalline silicon cells.
关键词： pyramidal texture uniformity,texturing process optimization,uniformity coefficient,photoelectric conversion efficiency,monocrystalline silicon solar cells
更新于2025-09-19 17:13:59
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Influence of TiO <sub/>2</sub> layer on ultimate efficiencies for planar and nano-textured CH <sub/>3</sub> NH <sub/>3</sub> PbI <sub/>3</sub> solar cells
摘要： The influence of TiO2 layer on the ultimate efficiencies, η, i.e. efficiencies without considering carrier recombination, for the planar and nano-textured CH3NH3PbI3 (MAPbI3) perovskite solar cells (SCs) are investigated. In planar TiO2/MAPbI3 heterojunction SCs, in order to achieve the largest power conversion efficiency (PCE), the TiO2 layer thickness, d1, is important. With the finite difference time domain (FDTD) method, we demonstrated that when the MAPbI3 layer thickness, d2, is 250 nm, which is a common-most MAPbI3 layer thickness for perovskite SCs, η achieves maximum when d1 is 80 nm. Fabricating nano textures on SC surface is an important method to improve the PCE. We studied the effects of d1 and d2 on the optimized η, η0, for two kinds of nano-textured perovskite SCs: the SCs with the nontextured TiO2 layer and the column-shaped nano hollow (CLH) textured MAPbI3 layer, defined as the nontextured-TiO2/CLH-MAPbI3 SCs, and the SCs with CLH textured TiO2 and CLH textured MAPbI3 layers of the same hollow axes and radius, defined as the CLH-(TiO2/MAPbI3) SCs. Generally, when d1 and d2 are fixed, η0 for the CLH-(TiO2/MAPbI3) SC is larger than that for the nontextured-TiO2/CLH-MAPbI3 SC by ca. 5%.
关键词： power conversion efficiency,perovskite solar cell,FDTD method,nano texture,light absorption
更新于2025-09-19 17:13:59
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Solar Radiation Pressure Enabled Femtosatellite Based Earth Remote Sensing
摘要： We examine the performance of an automated sea ice classification algorithm based on TerraSAR-X ScanSAR data. In the first step of our process chain, gray-level co-occurrence matrix(GLCM)-based texture features are extracted from the image. In the second step, these data are fed into an artificial neural network to classify each pixel. Performance of our implementation is examined by utilizing a time series of ScanSAR images in the Western Barents Sea, acquired in spring 2013. The network is trained on the initial image of the time series and then applied to subsequent images. We obtain a reasonable classification accuracy of at least 70% depending on the choice of our ice-type regime, when the incidence angle range of the training data matches that of the classified image. Computational cost of our approach is sufficiently moderate to consider this classification procedure a promising step toward operational, near-realtime ice charting.
关键词： Earth and atmospheric sciences,pattern analysis,texture,remote sensing
更新于2025-09-19 17:13:59
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Evidence for Self-healing Benign Grain Boundaries and a Highly Defective Sb <sub/>2</sub> Se <sub/>3</sub> a??CdS Interfacial Layer in Sb <sub/>2</sub> Se <sub/>3</sub> Thin-Film Photovoltaics
摘要： The crystal structure of Sb2Se3 gives rise to unique properties that cannot otherwise be achieved with conventional thin-film photovoltaic materials, such as CdTe or Cu(In,Ga)Se2. It has previously been asserted that, grain boundaries can be made benign provided only the weak van der Waals forces between the (Sb4Se6)n ribbons are disrupted. Here it is shown that non-radiative recombination is suppressed even for grain boundaries cutting across the (Sb4Se6)n ribbons. This is due to a remarkable self-healing process whereby atoms at the grain boundary can relax to remove any electronic defect states within the band gap. Grain boundaries can however impede charge transport due to the fact that carriers have a higher mobility along the (Sb4Se6)n ribbons. Because of the ribbon misorientation certain grain boundaries can effectively block charge collection. Furthermore, it is shown that CdS is not a suitable emitter to partner Sb2Se3 due to Sb and Se inter-diffusion. As a result a highly defective Sb2Se3 interfacial layer is formed that potentially reduces device efficiency through interface recombination.
关键词： Sb2Se3-CdS interface,grain boundary relaxation,grain texture,Kirkendall voids,Sb2Se3 photovoltaics
更新于2025-09-19 17:13:59
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Development of a flexible low laser power hybrid (LLPH) technology for shipbuilding including additive manufacturedsemi-automated hand-held unit
摘要： A novel Low Laser Power Hybrid (LLPH) technology overcomes manufacturing gaps between 2D panels and 3D sections in shipbuilding. Construction, process, equipment and additive manufacturing knowledge are combined in the project “ShipLight”. This paper highlights part conditions, requirements for process and safety issues plus the new automated and semi-automated hand-held unit. Geometrical studies on shipbuilding material reveal dependencies between gap width, weld speed, and energy input per unit length as well as camera-based joint recognition with quality assurance aspects and weld seam calculation resulting in the adaption of welding parameters under field conditions. The last part briefly sketches the development of the semi-automated hand-held unit. Additive manufacturing is utilized in part mock-up studies and prototyping. An outlook is given on further upcoming applications.
关键词： Low Laser Power Hybrid (LLPH) Technology,Shipbuilding,Optical Seam Tracking,Texture-based Image Processing,Laser Hybrid Welding,Additive Manufacturing,Semi-automated Hand-held Unit
更新于2025-09-16 10:30:52
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[IEEE IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Yokohama, Japan (2019.7.28-2019.8.2)] IGARSS 2019 - 2019 IEEE International Geoscience and Remote Sensing Symposium - Extraction of a Specific Land-Cover Class from Very High Spatial Resolution Imagery Using Positive and Unlabeled Learning with Convolutional Neural Networks
摘要： In remote sensing, supervised multiclass classifiers show a very promising performance in terms of classification accuracy. However, they require that all classes, in the study area, are labeled. In many applications, users may only be interested in specific land classes. When considering only one class, this referred to as One-Class classification (OC) problem. In this paper, we investigated the possibility of using Convolutional Neural Networks (CNN) within the Positive and Unlabeled Learning (PUL) framework for estimating the urban tree canopy coverage from very high spatial resolution aerial imagery. We also compared the proposed approach to the Binary CNN classification and to ensemble classifications based on various color-texture based features. The obtained classification accuracies show that PUL strategies provide competitive extraction results, especially the proposed CNN based one, due to the fact that PUL is a positive-unlabeled method in which large amounts of available unlabeled samples is incorporated into the training phase, allowing the classifier to model effectively the tree class.
关键词： convolutional neural networks,texture analysis,One-class classification,positive and unlabeled learning,ensemble classification
更新于2025-09-16 10:30:52
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Textured PDMS Films Applied to Thin Crystalline Silicon Solar Cells
摘要： Front surface texturization is a standard procedure used to improve optical properties of photovoltaic devices. In some particular cases, such as when dealing with ultrathin substrates, common texturization techniques can become unpractical or even unfeasible. Texturized polymer films applied on top of such devices may be used as an alternative. In this article, we report on the development of textured polydimethylsiloxane (PDMS) films to be placed on top of planar crystalline silicon solar cells based on thin substrates (≤40 μm). The PDMS polymer is deposited onto a rough surface (conventional random pyramid textured silicon), cured and detached from it. By scanning electron microscope images, we demonstrate that the dilution of PDMS into toluene helps in a better replica of the master surface. Next, we apply the optimized PDMS films on top of dummy samples based on 10, 20, and 40 μm thick crystalline silicon (c-Si) substrates whose reflectance is significantly reduced after placing the PDMS films. Accurate optical simulations indicate that the optical improvement comes from three mechanisms: higher light transmission into the device, lower reflectance at the c-Si surface, and better light trapping properties at the thin c-Si absorber. Experimental verification of the optical improvement with texturized PDMS films is reported based on 40 μm thick solar cell, where a short-circuit current density gain of 1.7 mA/cm2 is observed.
关键词： Surface texture,thin crystalline silicon solar cells
更新于2025-09-16 10:30:52
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A new uniformity coefficient parameter for the quantitative characterization of a textured wafer surface and its relationship with the photovoltaic conversion efficiency of monocrystalline silicon cells
摘要： A new parameter, the uniformity coefficient (UC), was proposed to overcome the difficulty in quantitatively characterizing the uniformity of the pyramidal textured surface of silicon wafers widely used for monocrystalline silicon cells (MSCs). The UC was defined based on the areal material ratio Smr(c) from the standard ISO 25178-2. First, the values of Smr(c) for MSC wafer surfaces with a uniform texture and an arbitrary texture were calculated. For the ideal uniform texture, Smr(c) was calculated using one pyramid assuming equal pyramids distributed over the wafer surface. For any arbitrary texture, based on the pyramidal geometrical structure, Smr(c) was calculated from the heights of pyramids extracted from their 2D projections. Second, the areas bounded by the Smr(c) curves with two coordinate axes were calculated accordingly. Then, the ratio of the two areas was defined as the UC. Fifteen kinds of monocrystalline silicon wafers were prepared by chemical texturing for 5 min, 15 min, 25 min, 35 min and 45 min with three groups of solutions, and the corresponding MSCs were fabricated. The UCs of the fifteen silicon wafers and the photovoltaic conversion efficiencies (PCEs) of the MSCs were tested. The relationships between the UC, texturing process (solution and time) and PCE were analyzed. The PCE increased monotonically with an increase in the UCs The silicon wafer obtained by texturing with 2% TMAH solution for 25 min had a textured surface with a maximum UC of 0.89, and the MSC exhibited a maximum PCE of 20.3%. The experimental results indicated that the UC is an effective parameter for the quantitative characterization of the pyramidal texture of silicon wafer surfaces and has a definite relationship with the PCE of the MSC. The UC is a useful and convenient measure for texturing process optimization.
关键词： Uniformity coefficient (UC),Quantitative characterization,Monocrystalline silicon cell (MSC),Pyramidal texture,Photovoltaic conversion efficiency (PCE),Areal material ratio Smr(c)
更新于2025-09-16 10:30:52
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[Institution of Engineering and Technology 20th Italian National Conference on Photonic Technologies (Fotonica 2018) - Lecce, Italy (23-25 May 2018)] 20th Italian National Conference on Photonic Technologies (Fotonica 2018) - Polarization digital holography for birefringence characterization of sperm cells
摘要： Birefringence in sperm heads depends on a very compact and organized structural normality. Additionally, when the acrosome reaction happens, due to a reorganization of the proteins, the birefringence occurs only in the post-acrosomal region. Thus, the polarization state of the semen is an interesting method to characterize their healthy state and to select reacted sperm cells. In this paper, a characterization of the birefringence pattern of sperm head by polarized digital holography microscopy is presented as a label free technique.
关键词： Digital holography,Sperm selection,Digital morphology,Sperm texture,Birefringence
更新于2025-09-16 10:30:52