Search Results (23)

Ice formation on critical infrastructure such as wind turbine blades can lead to severe performance degradation and safety hazards. This study investigates the use of hyperspectral imaging (HSI) combined with machine learning to detect and classify ice on various coated and uncoated surfaces. Hyperspectral reflectance data were acquired using a push-broom HSI system under controlled laboratory conditions, with ice and rime ice generated using a thermoelectric cooling setup. Support Vector Machine (SVM) and Random Forest (RF) classifiers were trained on uncoated aluminum samples and evaluated on surfaces with different coatings to assess model generalization. Both models achieved high classification accuracy, though performance declined on black-coated surfaces due to increased absorbance by the coating. The study further examined the impact of spectral band reduction to simulate different sensor types (e.g., NIR vs. SWIR), revealing that model performance is sensitive to wavelength range, with SVM performing optimally in a reduced band set and RF benefiting from the full spectral range. A multiclass classification approach using RF successfully distinguished between glaze and rime ice, offering insights into more targeted mitigation strategies. The results confirm the potential of HSI and machine learning as robust tools for surface ice monitoring in safety-critical environments. Full article

In the field of ceramic product defect detection, traditional manual visual inspection methods suffer from low efficiency and high subjectivity, while existing deep learning algorithms are limited in detection efficiency due to their high complexity. To address these challenges, this study proposes a deep learning-based algorithm for ceramic product defect detection. The algorithm designs a lightweight YOLOv10s detector, which reconstructs the backbone network using GhostNet and incorporates an Efficient Channel Attention (ECA) mechanism fused with depthwise separable convolutions, effectively reducing the model’s complexity and computational load. Additionally, an adaptive threshold method is proposed to improve the traditional Canny edge detection algorithm, significantly enhancing its accuracy in defect edge detection. Experimental results demonstrate that the algorithm achieves an mAP@50 of 92.8% and an F1-score of 90.3% in ceramic product defect detection tasks, accurately identifying and locating four types of defects: cracks, glaze missing, damage, and black spots. In crack detection, the average Edge Localization Error (ELE) is reduced by 25%, the Edge Connectivity Rate (ECR) is increased by 15%, the Weak Edge Responsiveness (WER) is improved by 17%, and the frame rate reaches 40 frames per second (f/s), meeting real-time detection requirements. This algorithm exhibits significant potential in the field of ceramic product defect detection, providing solid technical support for optimizing the ceramic product manufacturing process. Full article

CuCrO₂ (mcconnellite) was synthesized using both the solid-state method and microwave dielectric firing. It was characterized as a novel black ceramic pigment for use in various industrial glazes. For the first time, the application of mcconnellite (CuCrO₂) and its coloured glazes as selective solar absorbers (SSA) for integral ceramic solar collectors has been reported. The addition of quartz or anatase as colour modifiers was investigated to prevent the bluing of the pigment in Zn-containing glazes, a phenomenon associated with the exsolution of copper. Furthermore, doping with lanthanide oxides was explored to address two key challenges: controlling the formation of pinhole defects in porcelain glazes, which are linked to the destabilization of Cu⁺, and adjusting the IR cut-off wavelength to improve its performance as SSA. Full article

Mīnā’ī wares, crafted during the 12th–13th centuries, represent some of the earliest examples of sophisticated painted enamel decoration by potters. Due to the thinness of these enamel layers, their detailed characterization remains challenging, even with the use of advanced techniques, such as Proton-Induced X-ray Emission (PIXE) analysis and Rutherford Backscattering Spectrometry (RBS). This study provides the first combined non-invasive analysis, using X-ray fluorescence (XRF) and Raman spectroscopy, of five shards attributed to mīnā’ī wares. For comparison, two İznik shards from the 17th century, which feature similarly styled but thicker enamel decorations, were also analyzed. Interestingly, the mīnā’ī paste was found to contain lead and tin, suggesting the use of a lead-rich frit in its composition. This finding was confirmed through micro-destructive analysis, using Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM–EDS). Elements, such as rubidium (Rb), strontium (Sr), yttrium (Y), and zirconium (Zr), produced significant XRF signals and effectively distinguished mīnā’ī wares from İznik wares. A uniform tin-rich glaze, measuring 300–500 µm in thickness, was used as a base layer for the much thinner painted mīnā’ī enamels. The colored areas (blue, turquoise, red, green, black, white, eggplant) revealed the presence of various coloring agents and phases, such as spinels, chromite, and ions like Cu²⁺ and Co²⁺, as well as opacifiers like cassiterite and lead–calcium/potassium arsenates. Two distinct cobalt sources were identified: one associated with arsenic and the other with manganese and nickel. These cobalt sources are comparable to those used in İznik pottery. For the first time, boron was detected in the blue enamel of mīnā’ī wares. Full article

The Guangyuan kiln, located in the Sichuan Province, Southwest China during the Song Dynasty (960–1279 A.D.), is renowned for its high-temperature iron-series glazed wares, including pure black glazed ware, hare’s fur glazed ware, glossy brown glazed ware, and matte brown glazed ware. To elucidate the raw materials, processing techniques, and coloration mechanisms of these wares, multiple analytical experiments were employed to investigate chemical composition, microstructure, and the phase of Fe-bearing minerals. We found that glossy brown glazed ware has the highest Fe₂O₃ content in the glaze (7.67 wt% on average), while pure black glazed ware exhibits the lowest (4.84 wt% on average). Higher Fe₂O₃ content leads to more iron for Fe-bearing mineral crystallization and larger ε-Fe₂O₃ precipitation. Based on microscopic observations, pure black glazed ware has numerous 100–250 nm crystalline grains, while hare’s fur glaze ware features dendritic crystal flowers (200–400 nm), which exhibited liquid-liquid phase separation within the glaze, suggesting localized phase separation inducing iron oxide crystallization. Glossy brown glazed ware contains well-developed ε-Fe₂O₃ crystals (25 µm), and matte brown glazed ware, with the highest CaO and total flux, has acicular anorthite crystals alongside ε-Fe₂O₃ crystals. In summary, the decorative effect of four different types of iron-series glazed wares is determined by their chemical composition, phase composition, and microscopic structure. The findings offer valuable insights for the study of ancient iron-glazed ware. Full article

A flat-plate unglazed solar water heater (SWH) with a polymer thermal absorber was developed and experimented with. Polymer thermal absorbers could be a viable alternative to metal thermal absorbers for SWH systems. The performance of this polymer SWH system was measured based on inlet and outlet water temperature, water flow rate, ambient air temperature and solar irradiance. The polymer thermal absorbers were hollow Polyvinyl Chloride (PVC) tubes with a 20 mm external diameter and 3 mm thickness and were painted black to enhance radiation absorption. The pipes are arranged in a rectangular spiral inward–outward alternating-flow (RSioaf) pattern. The collector pipes were placed in a 1 m × 1 m enclosure with bottom insulation and a reflective surface for maximized radiation absorption. Water circulated through a closed loop with an uninsulated 16 L storage tank, driven by a pump and controlled by two valves to maintain a mass flow rate of 0.0031 to 0.0034 kg·s⁻¹. The test was conducted under a partially clouded sky from 9 a.m. to 5 p.m., with solar irradiance between 105 and 1003 W·m⁻² and an ambient air temperature of 27–36 °C. This SWH system produced outlet hot water at 65 °C by midday and maintained the storage temperature at 63 °C until the end of the test period. Photothermal energy conversion was recorded, showing a maximum value of 23%. Results indicate that a flat-plate solar water heater with a polymer thermal absorber in an RSioaf design can be an effective alternative to an SWH with a metal thermal absorber. Its performance can be improved with glazing and optimized tube sizing. Full article

The crystalline morphology and glaze color of Jian Kiln oil-spot glaze porcelain exhibit artistic beauty, making it one of the typical representatives of iron-based crystallized black porcelain from the Song Dynasty in China. This study sampled a series of specimens from key temperature points during simulation experiments, employing rapid air quenching to preserve the high-temperature state, capturing the formation process of oil-spot glaze crystals in Jian kiln ceramics. Key samples were subjected to microscopic structure and phase analysis using scanning electron microscopy (SEM), laser Raman spectroscopy (LRS), and X-ray photoelectron spectroscopy (XPS), revealing the formation mechanism of oil-spot glaze crystals in Jian kiln ceramics. The results indicate that the bubbles generated from the decomposition of iron oxide at high temperatures facilitate the migration and enrichment of iron-rich particles towards the glaze surface, laying a crucial material foundation for the subsequent crystallization process. The high-temperature reducing atmosphere accelerates the decomposition reaction of iron oxide, altering the concentration of Fe²⁺ in the glaze, the viscosity of the melt, and the surface tension, all of which are critical conditions that promote the formation of oil-spot glaze crystals. During the cooling phase, Fe₃O₄ nanocrystals oxidize into ε-Fe₂O₃ crystals, with external iron sources migrating inward to support ε-Fe₂O₃ crystal growth. This process gradually leads to the formation of micrometer-scale, leaf-shaped ε-Fe₂O₃ crystals that fully occupy the crystalline spots. The coloration of crystalline spots is closely tied to the size of the crystals. Thus, by adjusting the cooling regime, it is possible to create iron-based crystallization glazes with innovative color effects. Furthermore, this study offers significant insights for understanding the crystallization mechanisms of other ancient Chinese high-temperature iron-based crystallization glazes. Full article

Stainless steel dust is rich in valuable metal elements including Fe, Cr, Ni and Mn, which can be utilized to prepare Fe–Cr–Ni–Mn series black pigments. Meanwhile, manganese can absorb the majority of the visible light wavelength range, which improves the color rendering performance of Fe–Cr–Ni–Mn series black pigments. However, the coloring mechanism of manganese in the above black pigments is not clear. Therefore, the effect of manganese oxide content on the preparation of spinel-type black pigments from microwave-assisted calcination of stainless steel dust was studied in this work. The results show that with the increase in MnO content in the raw mixture, the crystal plane spacing of black pigments increases from 0.2525 nm to 0.2535 nm, the grain size grows from 61.4619 nm to 79.7171 nm, and the lattice constant grows from 0.8377 to 0.8406 nm. Moreover, the band gap is decreased from 1.483 eV to 1.244 eV, the absorbance increases significantly and has a consistent absorbance in the visible range, and the L*, a* and b* values reduce from 41.8, 0.6, 1.6 to 32.0, 1.0, 0.8, respectively. MnO can react with the spinel in stainless steel dust, forming Mn₃O₄, MnCr₂O₄ and Ni (Fe,Cr)O₄ in the system, with a regular polyhedral structure. The prepared pigments have excellent thermal stability at 1100 °C and good compatibility with transparent glazes, which can be adhered to the surface of ceramic tiles after calcination to demonstrate better compatibility as the content of MnO increases. Full article

In this study, the well-preserved glazes of 13 colored bricks representative of the decoration of the palaces of Sargon II (Khorsabad, 8th century BC) and of Darius I (Susa, 6th century BC) were examined. The purpose of this research is to gather information about the ancient brick manufacturing processes by examining the colored glazes and, in particular, black glazes using a combination of methods that included optical microscopy, SEM-EDX, synchrotron µ-XRD, and µ-Raman spectroscopy. The results revealed different coloring techniques for producing black glazes in the Neo-Assyrian and Persian Achaemenid periods. Regarding the black glazes of Susa, it is particularly interesting to note that their chemical composition varies according to the function of the glazes on the bricks: manganese oxide (for colored fields of glaze) and iron-rich compounds (for raised lines separating glazed areas). In comparison, the black glazes from Khorsabad are characterized by the presence of spherical copper sulfide and galena nanoparticles (ranging from less than 100 nm to about 1 µm) for both the glazed areas and the separating lines. This coloring technique to obtain black glazes is very rarely described in the literature, as well as the mechanism of formation of these spherical nanoparticles. Full article

Raw materials significantly determine the final composition and properties of a fired ceramic. Raman analysis which characterizes micro- and nanostructures of (coloured) glazes, opacified or not, was applied to shards mostly collected before the 1960s, currently at the Louvre Museum, originated in Anatolia, the Caucasus, Iran and Central Asia, which are, for most of them, characterized by the use of black lines to separate coloured areas, and dated to the period between the 12th and 19th centuries. Measurements were carried out in the laboratory with a blue laser excitation and/or on the conservation site with a mobile device (green laser). Three types of glazes were identified by their nanostructure of the silicate network: (i) a lead-rich glaze analogous to that of Byzantine, Zirid to Hafsid and al-Andalus productions, (ii) a lead-alkali glaze typical of the Ottoman productions of Iznik-Kütahya, and (iii) a mixed (poor lead/lead-free)-alkali glaze typical of Safavid productions. The colour determines the precise composition of the glaze. The identification is not only based on the signature of the stretching mode of the SiO₄ tetrahedron (position of the wavenumber of the component(s)) but also on the position and shape of the continuous luminescence of the Raman background, characteristic of the raw materials used. Lead-tin yellow, Fe-rich, Mn-rich and Cr-rich black pigments and opacifiers made of cassiterite and wollastonite were also identified. The results (type of glaze and deduced processing temperature) were discussed in the light of the ternary phase diagrams visualizing elemental composition determined in previous works and the microstructure examination on the polished section (defining single or multistep firing cycles). Continuity was highlighted on the one hand between the tiles of Bursa, Edirne and Istanbul (Ottoman Iznik-like production) and on the other hand between those of Samarkand area (Timurid) and Iran. The procedure was then applied in the study of three objects (two dishes and a bowl) which are very representative of the productions of the Turkish-Persian cultural areas: a polychrome mina’i cup with decoration representing a rider, an Ottoman Iznik fritware with polychrome floral decoration, and a blue-and-white Safavid ceramic with a decoration representing a shrub. Full article

Clinobisvanite (monoclinic scheelite BiVO₄, S.G.I2/b) has garnered interest as a wide-band semiconductor with photocatalyst activity, as a high NIR reflectance material for camouflage and cool pigments and as a photoanode for PEC application from seawater. BiVO₄ exists in four polymorphs: orthorhombic, zircon-tetragonal, monoclinic, and scheelite-tetragonal structures. In these crystal structures, V is coordinated by four O atoms in tetrahedral coordination and each Bi is coordinated to eight O atoms from eight different VO₄ tetrahedral units. The synthesis and characterization of doped bismuth vanadate with Ca and Cr are studied using gel methods (coprecipitated and citrate metal–organic gels), which are compared with the ceramic route by means of the UV–vis–NIR spectroscopy of diffuse reflectance studies, band gap measurement, photocatalytic activity on Orange II and its relation with the chemical crystallography analyzed by the XRD, SEM-EDX and TEM-SAD techniques. The preparation of bismuth vanadate-based materials doped with calcium or chromium with various functionalities is addressed (a) as pigments for paints and for glazes in the chrome samples, with a color gradation from turquoise to black, depending on whether the synthesis is by the conventional ceramic route or by means of citrate gels, respectively; (b) with high NIR reflectance values that make them suitable as fresh pigments, to refresh the walls or roofs of buildings colored with them; and (c) with photocatalytic activity. Full article

Jian tea bowls are greatly appreciated not only due to their thick and lustrous black glazes, but also their exquisite streaked and mottled patterns. Researches on the firing process and colouring mechanism of typical hare’s fur and oil spot Jian glazes have continuously been carried out in the past decades; however, there are few reports about other scarce types of black-glazed porcelains excavated from the Jian kiln site. In this work, we report on a multi-technique analysis of the surface and cross-sectional structure, phase, morphology and chemical composition of three rare types of Jian tea bowls (tea-dust-glazed ware, grey-glazed ware and pearl-glazed ware) combining optical and spectroscopic methods such as optical coherence tomography (OCT), optical microscopy (OM), Portable energy dispersive X-ray fluorescence spectrometry (XRF), laser-Raman spectroscopy (LRS) and scanning electron microscopy coupled with an X-ray energy dispersive spectrometer (SEM-EDS). Results revealed that the tea dust glaze was one high-temperature iron-based crystalline glaze, and its glaze was characterized by a transparent glass matrix; irregular pits completely or partially filled by TiO₂; and that ε-Fe₂O₃ and residual quartz were randomly distributed all over the surface, which produced the appearance of tea-dust. The grey-glazed porcelain was fired at a lower temperature in the dragon kiln than that of the traditional hare’s fur and oil spot samples, its glaze contained some residual quartz, and anorthite crystals showed a serried distribution along the thickness. The pearl-glazed porcelain was fired through a secondary glazing process via artificial stippling quartz powder. This work provides guidance for the firing process of three rare types of Jian wares and has not only scientific but also cultural profound significance, which reveals the features of their historical heritage. Full article

In the world of nanomaterials and meta-materials, thin films are used which are an order of magnitude thinner than historically used in optical thin film coatings. A problem stems from the island structure that is seen as the film nucleates and grows until there is coalescence or percolation of the islands into a nearly continuous film. The application problem is that the indices of refraction, n and k, vary with thickness from zero thickness up to some thickness such as 30 or 40 nanometers for silver. This behavior will be different from material to material and deposition process to deposition process; it is hardly modeled by simple mathematical functions. It has been necessary to design with only fixed thicknesses and associated indices instead. This paper deals with a tool for the practical task of designing optical thin films in this realm of non-bulk behavior of indices of refraction; no new research is reported here. Historically, two applications are known to have encountered this problem because of their thin metal layers which are on the order of 10 nm thick: (1) architectural low emittance (Low-E) coatings on window glazing with thin silver layers, and (2) black mirrors which transmit nothing and reflect as little as possible over the visible spectrum with thin layers of chromium or related metals. The contribution reported here is a tool to remove this software limitation and model thin layers whose indices vary in thickness. Full article

(1) Background: Considering that the appearance of a dental material is an important factor that contributes to the success of prosthetic restorations. The purpose of this study is to investigate the optical properties and color changes among the layers of three commercial zirconias, to compare the aspect of the polished and glazed surfaces before and after aging and to evaluate the effects of hydrothermal degradation on their aesthetics. (2) Methods: Forty-eight plate-shaped samples were sectioned from presintered blocks of each multilayer translucent zirconia with different Yttrium content: Ceramill Zolid fx ML (5 mol%) = CeZ, STML (4 mol%) = STM, IPS e.maxZirCAD CEREC/in Lab MT Multi (4 mol% + 5 mol%) = IPZ. The samples were sintered according to the recommendation of each manufacturer, and half (24) of them were polished and the other half (24) glazed on one of the surfaces. Each type was equally divided into one control and one aging group, and, for each material, this resulted in four groups (n = 12): polished-control, polished-autoclaved glazed-control, and glazed-autoclaved. The artificial aging was carried out with an autoclave and distilled water at 134 °C, 0.2 MPa for 1 h, and for optical parameters (TP, CR, OP) and color change (ΔE*) measurements on a black and white background in a CIE L*a*b* color system, a spectrophotometer was used. The specimens were evaluated in incisal, cervical, and medium areas on polished and glazed samples before and after the aging stage. Statistical analysis was achieved with a two-way ANOVA test, the unpaired t-test, and the paired t-test. (3) Results: Before and after aging, the mean TP values for polished samples were higher than the glazed ones. After aging, the mean TP values increased for all groups (except polished CeZ), and significant differences were reported for polished STM, IPZ. After LTD, the opalescence registered an increase for almost all groups (except polished CeZ, polished and glazed IPZ—medium area), and significant differences were reported for almost all groups (except STM—incisal, IPZ—cervical, medium areas). The levels of color change were between extremely slight to perceivable. (4) Conclusions: Optical properties of the selected multilayer zirconia were influenced by polishing and glazing as surface treatment and affected by artificial aging (CeZ the least); perceivable color changes for polished STM, IPZ were detected. Full article

The manuscript is written for flow escalation based on an experimental data for a Solar Assisted Heat Pump Water Heater (SAHPWH) increasing building energy efficiency. For the investigation, a Solar Assisted Heat Pump (SAHP) was conceived, manufactured, and tested in real time. The findings of the experiments shows that single glazing with average sun radiation of 600–750 W/m², COP of approx. 6 can be obtained with identical heat gains. This study shows that when a flat plate collector of area 1.83 m (L) × 1.22 m (W) × 0.1 m (T) with a 0.5-mm-thick black copper plate absorber with clear glazing as a cover receives average radiation of 700 W/m², then setup can supply 60 litres of water for residential use from 15 °C to 45 °C in approx. 70 min. In addition, the study finds that the collector efficiency factor F’ is likewise shown to have a direct connection with the absorber and an inverse relationship of tube spacing. The findings indicated that the technology has significant commercial potential, particularly in sectors such as with solar resources for improving building energy efficiency. Full article