More Like this

1. A method for the taphonomic assessment of bone tools using 3D surface texture analysis of bone microtopography

   https://doi.org/10.1007/s12520-020-01195-y  

   Martisius, Naomi L.; McPherron, Shannon P.; Schulz-Kornas, Ellen; Soressi, Marie; Steele, Teresa E. (October 2020, Archaeological and Anthropological Sciences)

   Abstract Increasingly researchers have employed confocal microscopy and 3D surface texture analysis to assess bone surface modifications in an effort to understand ancient behavior. However, quantitative comparisons between the surfaces of purported archaeological bone tools and experimentally manufactured and used bones are complicated by taphonomic processes affecting ancient bone. Nonetheless, it may be reasonable to assume that bones within the same deposits are altered similarly and thus these alterations are quantifiable. Here we show how unworked bones can be used to quantify the taphonomic effect on bone surfaces and how this effect can then be controlled for and incorporated into an analysis for evaluating the modified surfaces of purported bone tools. To assess the baseline taphonomy of Middle Paleolithic archaeological deposits associated with typologically identified bone artifacts, specifically lissoirs , we directly compare the surface textures of ancient and modern unworked ribs. We then compare the ancient unworked ribs and lissoirs to assess their differences and predict the ancient artifacts’ original surface state using a multilevel multivariate Bayesian model. Our findings demonstrate that three of five tested surface texture parameters ( Sa , Spc , and IsT ) are useful for distinguishing surface type. Our model predictions show that lissoirs tend to be less rough, have more rounded surface peaks, and exhibit more directionally oriented surfaces. These characteristics are likely due to anthropogenic modifications and would have been more pronounced at deposition. Quantifying taphonomic alterations moves us one step closer to accurately assessing how bone artifacts were made and used in the ancient past. 

   more » « less
2. The geodiv r package: Tools for calculating gradient surface metrics

   https://doi.org/10.1111/2041-210X.13677  

   Smith, Annie C.; Dahlin, Kyla M.; Record, Sydne; Costanza, Jennifer K.; Wilson, Adam M.; Zarnetske, Phoebe L. (January 2021, Methods in Ecology and Evolution)

   Goslee, Sarah (Ed.)

   1. The geodiv r package calculates gradient surface metrics from imagery and other gridded datasets to provide continuous measures of landscape heterogeneity for landscape pattern analysis. 2. geodiv is the first open-source, command line toolbox for calculating many gradient surface metrics and easily integrates parallel computing for applications with large images or rasters (e.g. remotely sensed data). All functions may be applied either globally to derive a single metric for an entire image or locally to create a texture image over moving windows of a user-defined extent. 3. We present a comprehensive description of the functions available through geodiv. A supplemental vignette provides an example application of geodiv to the fields of landscape ecology and biogeography. 4. geodiv allows users to easily retrieve estimates of spatial heterogeneity for a variety of purposes, enhancing our understanding of how environmental structure influences ecosystem processes. The package works with any continuous imagery and may be widely applied in many fields where estimates of surface complexity are useful. 

   more » « less
3. Effect of Prior Surface Textures on the Resulting Roughness and Residual Stress during Bead-Blasting of Electron Beam Melted Ti-6Al-4V

   https://doi.org/10.3390/cryst12030374  

   Rifat, Mustafa; Basu, Saurabh; De Meter, Edward C.; Manogharan, Guha (March 2022, Crystals)

   The finishing of additive manufactured (AM) components is crucial for endowing them with fatigue resistance. Unfortunately, current AM processes naturally promote anisotropic surface characteristics that make it challenging to optimize finishing processes. In this study, bead-blasting is explored as a process for finishing Electron Beam Melted (EBM) Ti-6Al-4V. The effects of anisotropic roughness characteristics on the mechanics of bead-blasting are delineated using surface texture measurements via optical profilometry and residual stress measurements via X-ray diffraction. As-received surfaces resulting from AM, as well as those that have been Electrical Discharge Machined (EDM), are studied. It is seen that pre-processed roughness textures heavily influence the final textures and residual stresses. These linkages are quantified using a plasticity index as the governing metric—a rougher surface features a larger plastic index, which results in comparatively greater evolution of its texture characteristics than a smoother surface after equivalent bead-blasting treatments. The mechanics of this evolution are delineated using energy-controlled indentation as a model representing a single impact in bead-blasting. It is seen that rougher surfaces featuring complex textures in as-received states also produce complex stress states featuring a greater level of locally tensile stresses during indentation compared with smoother surfaces. Approaches to address these complications are proposed that can potentially transform a printed, non-functional surface into one that is optimized for fatigue resistance. 

   more » « less
4. On the correlation between second order texture features and human observer detection performance in digital images

   https://doi.org/10.1038/s41598-020-69816-z  

   Nisbett, William H.; Kavuri, Amar; Das, Mini (August 2020, Scientific Reports)

   Abstract Image texture, the relative spatial arrangement of intensity values in an image, encodes valuable information about the scene. As it stands, much of this potential information remains untapped. Understanding how to decipher textural details would afford another method of extracting knowledge of the physical world from images. In this work, we attempt to bridge the gap in research between quantitative texture analysis and the visual perception of textures. The impact of changes in image texture on human observer’s ability to perform signal detection and localization tasks in complex digital images is not understood. We examine this critical question by studying task-based human observer performance in detecting and localizing signals in tomographic breast images. We have also investigated how these changes impact the formation of second-order image texture. We used digital breast tomosynthesis (DBT) an FDA approved tomographic X-ray breast imaging method as the modality of choice to show our preliminary results. Our human observer studies involve localization ROC (LROC) studies for low contrast mass detection in DBT. Simulated images are used as they offer the benefit of known ground truth. Our results prove that changes in system geometry or processing leads to changes in image texture magnitudes. We show that the variations in several well-known texture features estimated in digital images correlate with human observer detection–localization performance for signals embedded in them. This insight can allow efficient and practical techniques to identify the best imaging system design and algorithms or filtering tools by examining the changes in these texture features. This concept linking texture feature estimates and task based image quality assessment can be extended to several other imaging modalities and applications as well. It can also offer feedback in system and algorithm designs with a goal to improve perceptual benefits. Broader impact can be in wide array of areas including imaging system design, image processing, data science, machine learning, computer vision, perceptual and vision science. Our results also point to the caution that must be exercised in using these texture features as image-based radiomic features or as predictive markers for risk assessment as they are sensitive to system or image processing changes. 

   more » « less
5. A MATLAB-Based User Interface to Study the Multi-Reflections and Light Absorption in Textured Solar Cell Surfaces

   https://doi.org/10.1115/IMECE2024-145782  

   Singh, Lovekesh; Hossain, Mohammad (November 2024, American Society of Mechanical Engineers)

   Improving the efficiency of solar cells is important as it is a sustainable way of energy production with a relatively low power conversion efficiency (PCE). To enhance the efficiency of solar cells, textures can be introduced on the surface which can minimize light ray reflectance, leading to increased light absorption and improvement in overall efficiency. Introduction of texture can also improve the hydrophobicity of the surface which can enhance the self-cleaning capability of solar panels. In this study, a MATLAB-based user interface is developed to facilitate assessing the sunlight absorption in silicon-based solar cells having top layer as a microtextured surface. The user interface employs a multi-faceted mesh-grid algorithm to design 3D textural surface geometries. Core to the program’s functionality is advanced ray tracing simulations that identify points of light intersection on these textures and determine the trajectory of light upon reflection. A notable feature of this user interface is its capability to simulate and analyze the complex phenomenon of multi-reflection in the structure. This iterative process allows for a comprehensive understanding of light interactions in textured surfaces, to find the best structure for maximum absorption. This user-interface provides clarity and ease of use in modeling and analyzing light absorption in textured solar cell surfaces. The modeling framework is validated using experimental observation, and the impact of six 3D surface textures on sunlight absorption of silicon solar cell is studied using the simulation framework. According to the simulation findings, the cavity texture provides more consistent light absorption compared to its protrusion counterpart. Furthermore, hemispherical cavities exhibit consistently high absorption across various incident angles. The results provide useful insights for improving light absorption in the solar cell. 

   more » « less