Material Processing Research Articles

Flow Analysis of Centrifugal Compressor using ANSYS

Abstract: The aerodynamic and structural designs of the impeller are vital to the functioning of the entire compressor stage in centrifugal compressors. In contrast to previous years, there has been a greater demand for industrial centrifugal compressors to operate with greater efficiency and operational range. Although the efficiency of low-pressure-ratio centrifugal compressors has nearly achieved its maximum, intermediate and high-pressure ratio machines still lag behind the state-of-the-art in terms of efficiency. Maintaining maximum efficiency while extending the working range is a challenging task in centrifugal compressor design. Furthermore, a single design must be usable globally due to product globalisation, even in the face of technological disparities and variances in electricity frequency of up to 10 percent in some nations. Often operating at different rotational speeds, centrifugal compressors add another layer of complexity to the impeller structural design. A full-3D impeller design that is optimised for both structural integrity and aerodynamic performance is shown in this study .For air conditioning systems of the future, centrifugal compressor performance must be improved. This research focusses on systematic numerical simulation, a computationally efficient method of optimising centrifugal compressor performance. ANSYS simulations are used in conjunction with a thorough literature review on the aerodynamic behaviour of materials used in centrifugal compressors. For the purpose of performing flow simulations under subsonic circumstances with suitable boundary conditions and grid independence checks, geometric modelling was completed using CATIAV5R22 and imported into ANSYS. Tests were conducted using various aluminium materials and mass flow rates, and enhanced efficiency findings were confirmed by comparison with experimental data. Materials Processing and Characterisations is in charge of peer review.

TINJAUAN PEMANFAATAN KECERDASAN BUATAN: PEMBELAJARAN MANDIRI PADA KETERAMPILAN BAHASA INDONESIA

The research carried out aims to review the use of artificial intelligence in independent learning of Indonesian language skills. The research was carried out using a library study approach which included a series of activities related to the use of library data collection methods, reading and retrieval and processing of research materials. In this research, the data sources are books, journals or internet-based websites that contain the topic or discussion being researched. The data sources in this research include 30 references based on topics raised related to the use of artificial intelligence in independent learning of Indonesian language skills. Language skills include 4 abilities, namely listening, speaking, reading and writing. Writing skills are a reference in language skills which must be mastered by students because with writing activities students can express various imaginations or thoughts in writing. Duet AI can help students write essays, reports and other assignments better through the ‘help me write’ feature in Google Docs. First, Duet AI can help students improve their grammar and writing style. Their writing can be identified and corrected for errors in grammar, punctuation, and spelling. Duet AI can also provide feedback on the clarity of their writing. Second, Duet AI can help students develop their own unique writing style. Duet AI will provide feedback on the authenticity and creativity of their writing. It can also help them identify and avoid clichés and overused phrases.

Novel heat exploration investigation for bioconvected Oldroyd-B nanofluid with variable thermal conductivity and Arrhenius energy induced by nailed boundary

Oldroyd-B nanofluids have potential applications in enhanced heat transfer systems, drug delivery, and advanced material processing due to their unique rheological properties. Bioconvection finds applications in biomedical research, environmental monitoring, and optimizing fluid dynamics in biotechnological and pharmaceutical processes. Due to these applications current study investigates bioconvection in the flow of Oldroyd-B nanofluid subjected to Joule heating with convected boundaries. For uniqueness of problem the effects of variable thermal connectivity and activation energy are taken into account. In addation the influence of heat source and thermal radiation are part of current model. The governing PDEs of mathematical model incorporates the Oldroyd-B rheological framework to capture the viscoelastic nature of the fluid are transformed into ODEs via similarity solution. Matlab platform via shooting algorithm is involved to solve transformed system. Through numerical simulations the stimulus of involving parameters on velocity f ′(η) temperature θ(η), concentration ϕ(η), and microbes profile X(η) are displayed in graphical and tabulated form. For strength of problem the streamlines and graphs of physical quantities are also designed. It is noted that velocity curve decreased for increasing value of magnetics parameter and opposite trend is noted in velocity distribution for increasing value of mixed convection parameter λ . Moreover, thermal layer θ is diminished for growing value of Pr , a reverse relation is noted in concentration profile for value of activation energy.

In Situ Visual Observation of Surface Energy-Controlled Heterogeneous Nucleation of Metal Nanocrystals.

Electrochemical growth of metal nanocrystals is pivotal for material synthesis, processing, and resource recovery. Understanding the heterogeneous interface between electrolyte and electrode is crucial for nanocrystal nucleation, but the influence of this interaction is still poorly understood. This study employs advanced in situ measurements to investigate the heterogeneous nucleation of metals on solid surfaces. By observing the copper nanocrystal electrodeposition, an interphase interaction-induced nucleation mechanism highly dependent on substrate surface energy is uncovered. It shows that a high-energy (HE) electrode tended to form a polycrystalline structure, while a low-energy (LE) electrode induced a monocrystalline structure. Raman and electrochemical characterizations confirmed that HE interface enhances the interphase interaction, reducing the nucleation barrier for the sturdy nanostructures. This leads to a 30.92-52.21% reduction in the crystal layer thickness and a 19.18-31.78% increase in the charge transfer capability, promoting the formation of a uniform and compact film. The structural compactness of the early nucleated crystals enhances the deposit stability for long-duration electrodeposition. This research not only inspires comprehension of physicochemical processes correlated with heterogeneous nucleation, but also paves a new avenue for high-quality synthesis and efficient recovery of metallic nanomaterials.

Investigations on the processing of ceramic materials using Fused Filament Fabrication

This paper represents the current status of the investigation into the processing of ceramic components, using Fused Filament Fabrication (“FFF”). The process chain, beginning from the additive manufacturing (“AM”), through the post processing, the debinding and sintering procedure, to the finished part is described. The examined materials are silicon nitride (Si3N4) and silicon carbide (SSiC), prepared by the company SiCeram/Qsil. Furthermore, comprehensive investigations on the materials are done, both in the green and in the sintered state. In addition, sources of occurring problems and defects in the process chain are pointed out and possible solutions are shown. Finally, the current status of investigations, regarding to the transfer into the industry, is discussed.

MXene Composite Electromagnetic Shielding Materials: The Latest Research Status.

MXene emerges as a premier candidate for electromagnetic shielding owing to its unique properties as a novel two-dimensional material. Its exceptional electrical conductivity, chemical reactivity, surface tunability, and facile processing render it highly suitable for diverse electromagnetic shielding applications. The research status of MXene and MXene-based electromagnetic shielding materials is systematically discussed in this paper. First, the research status of MXene as a single-component electromagnetic shielding material is briefly introduced. Subsequently, the research status of composite structures constructed by MXene with polymers, carbon derivatives, and ferrites is introduced in detail. Furthermore, the research progress of MXene-based ternary and quaternary composite electromagnetic shielding materials is further focused. Finally, the application of MXene-based composite electromagnetic shielding materials is prospected. A deeper understanding of MXene's electromagnetic shielding properties is facilitated by this paper, providing the direction for the future development of two-dimensional materials in the design and processing of electromagnetic shielding materials.

An Analysis of Greenhouse Gas Emissions in Electrolysis for Certifying Clean Hydrogen

The drive for carbon neutrality has led to legislative measures targeting reduced greenhouse gas emissions across the transportation, construction, and industry sectors. Renewable energy sources, especially solar and wind power, play a pivotal role in this transition. However, their intermittent nature necessitates effective storage solutions. Green hydrogen and ammonia have gained attention for their potential to store renewable energy while producing minimal emissions. Despite their theoretical promise of zero greenhouse gas emissions during production, real-world emissions vary based on system configurations and lifecycle assessments, highlighting the need for detailed evaluations of their environmental impact. Therefore, in this study, calculations were performed for the actual amount of produced greenhouse gas emissions that are associated with the production of green hydrogen using electrolysis, from raw material extraction and processing to hydrogen production, with these assessed from well-to-gate emission estimates. Emissions were also evaluated based on various types of renewable energy sources in South Korea, as well as hydrogen production volumes, capacities, and types. Using these data, the following factors were examined in this study: carbon dioxide emissions from the manufacturing stage of electrolysis equipment production, the correlation between materials and carbon dioxide emissions, and process emissions. Current grades of clean hydrogen were verified, and the greenhouse gas reduction effects of green hydrogen were confirmed. These findings are significant against the backdrop of a country such as South Korea, where the proportion of renewable energy in total electricity production is very low at 5.51%. Based on the domestic greenhouse gas emission efficiency standard of 55 kWh/kgH2, it was found that producing 1 kg of hydrogen emits 0.076 kg of carbon dioxide for hydropower, 0.283 kg for wind power, and 0.924 kg for solar power. The carbon dioxide emissions for AWE and PEM stacks were 8434 kg CO2 and 3695 kg CO2, respectively, demonstrating that an alkaline water electrolysis (AWE) system emits about 2.3 times more greenhouse gasses than a proton exchange membrane (PEM) system. This indicates that the total carbon dioxide emissions of green hydrogen are significantly influenced by the type of renewable energy and the type of electrolysis used.

Physicochemical Methods for the Structuring and Assembly of MOF Crystals.

ConspectusMetal-organic frameworks (MOFs) are promising for various applications through the creation of innovative materials and assemblies. This potential stems from their modular nature, as diverse metal ions and organic linkers can be combined to produce MOFs with unique chemical properties and lattice structures. Following extensive research on the design and postsynthetic chemical modification of MOF lattices at the molecular level, increasing attention is now focused on the next hierarchical level: controlling the morphology of MOF crystals and their subsequent assembly and positioning to create functional composites.Beyond well-established methods to regulate crystal size and shape through nucleation and coordination modulation, physicochemical techniques leveraging wetting effects, interparticle interactions, and magnetic or electric fields offer attractive avenues for the hierarchical structuring and assembly of MOFs. These techniques facilitate crystal alignment and yield unique superstructures. While our research group primarily focuses on directing MOF crystal orientation and positioning using external stimuli such as magnetic and electric fields, we also explore hierarchical MOF synthesis and structuring using liquid interfaces and depletion force-assisted packing.This account highlights our journey and progress in developing methods to regulate the morphology, assembly, orientation, and positioning of MOF crystals, placed in the context of work by other groups. First, we examine commonly utilized structuring methods for MOF crystals that employ liquid-liquid and air-liquid interfaces to spatially confine reactions, allowing us to access unique morphologies such as mushroom-like crystals and Janus particles. We also discuss strategies for concentrating and packing MOF crystals into superstructures, utilizing fluid interfaces for spatial confinement of crystals, depletion forces, entropic effects, and crystal sedimentation.A particularly compelling challenge in expanding the applicability of MOF materials is how to manipulate free-standing MOF crystals. This issue is especially important because MOFs are typically produced as loose powders, and industrial material processing is generally more efficient when the material is fluidized. While extensive research has been conducted regarding MOF growth on substrates with both positional and orientational control, there is a clear need for similar precision with free-standing MOFs dispersed in a fluid matrix. Our group has thus focused on the relatively new, yet powerful approach of using electric and magnetic fields to manipulate MOF crystals, which offers unprecedented control over the orientation and positioning of dispersed MOF crystals, complementing the more well-established methods of MOF growth on substrates. In this Account, we provide foundational background and discussions on the interactions between these external fields and MOF crystals, including critical considerations for effective MOF manipulation using such techniques. We also discuss their unique advantages and applications, and briefly examine potential application areas, such as photonics, smart materials like soft robotics and absorbents, and sensing. This Account highlights the promising potential of well-organized and aligned MOF crystals over randomly oriented ones in various applications, owing to enhanced selectivity and performance. It underscores the importance of specialized assembly methods to advance materials science and engineering, encouraging the reader to explore such approaches.

Design solutions and characterization of a small scale and very high concentration solar furnace using a Fresnel lens

The use of Fresnel lenses for solar energy concentration technology dates back to the 1950 s. These lenses feature a plano-convex optical design with a series of discontinuous convex grooves. Typically made from materials like polymethyl methacrylate, Fresnel lenses are lightweight, resistant to sunlight, thermally stable, and cost-effective.This study presents a novel Fresnel lens-based solar furnace configuration installed at the Eduardo Torroja Institute for Construction Science in Madrid, Spain. The novelty of this work lies in the exceptional performance and operability of the facility. Experimental characterization revealed a record peak irradiance over 7 MW m−2 for an incident target power exceeding 800 W. Comparison with ray tracing simulations shows good agreement with experimental results. This setup enables high temperature experiments up to 2000 °C with rapid execution times. A fixed receiver, a shutter system and a closed-loop heliostat tracking control system allow for flexible operation up to 5000 suns and straightforward maintenance. The concentrator element costs less than 300 USD (2022) m−2, offering an economical solution to solar-powered high concentration and temperature applications. This innovative design overcomes previous operational challenges, providing a robust and economical method for high-temperature material processing and other industrial applications.

Recent Advances in Electroluminescent Metallic Nanoclusters: From Materials to Devices.

Metallic nanoclusters (MNCs) were developed rapidly in recent decades, owing to their unique electronic structures and excited state characteristics, leading to their wide applications. Luminescence as one of the most important functions for MNCs has also been used to realize biodetection, displays, and lighting, through either electrochemiluminescence (ECL) or electroluminescence (EL). Both emissive properties and electrochemical activities of MNCs were utilized to enhance ECL and EL through facilitating exciton formation and radiation, rendering the rapid emerging of the latter in the last ten years. Through ligand modification, radiative excited-state components were increased to realize state-of-the-art photo- and electroluminescence efficiencies up to ∼100% and ∼30%, as well as ultralow biodetection limits. Nonetheless, material selection space and processing technologies are still limited. Herein, we overview and discuss recent advances of MNCs-based ECL and EL, through both aspects of materials/systems and devices, which would enlighten continuous innovations in optoelectronic MNCs.

Degradation effects in FRNC jackets of optical fiber cables

AbstractIn large scale manufacturing, polymeric materials for cable jackets are subjected to high temperature and shear, what can induce degradation processes. In result, changes in structure of polymer materials can occur what is critical for their applications. Permanent market pressure on increase of productivity and product reliability as well as rigorous administrative regulations in telecommunication industry are the driving forces for development and introduction of new advanced Flame Retardant Non-corrosive jacketing materials. Despite many studies, their behavior is still neither well characterized nor understood in large-scale production. The object of studies was characterization of a relationship between processing conditions and effects of degradation of FRNC cable materials. The main goal was to find the processing factors limiting the production speed. Materials taken into consideration were two commercially available thermoplastic FRNC compounds dedicated to fiber optic cables, based on linear low-density polyethylene/ethylene–vinyl acetate composites with high loading of aluminum trihydroxide and magnesium dihydroxide fillers. Thermal degradation of cable materials was studied with use of thermogravimetry and rheometry. The series of jacket samples under different processing conditions were produced. Material processing behavior was characterized, and tensile and heat aging performance of cable jacket were tested. The results showed that the primary limiting factors for line speed increase were the melt pressure and jacket tensile performance, but neither the shrinkage nor extruder motor load. The result and general approach to the FRNC investigation can be successfully used in cable industry or in other industries involving the extrusion of FRNC materials.

A Review of an Investigation of the Ultrafast Laser Processing of Brittle and Hard Materials.

Ultrafast laser technology has moved from ultrafast to ultra-strong due to the development of chirped pulse amplification technology. Ultrafast laser technology, such as femtosecond lasers and picosecond lasers, has quickly become a flexible tool for processing brittle and hard materials and complex micro-components, which are widely used in and developed for medical, aerospace, semiconductor applications and so on. However, the mechanisms of the interaction between an ultrafast laser and brittle and hard materials are still unclear. Meanwhile, the ultrafast laser processing of these materials is still a challenge. Additionally, highly efficient and high-precision manufacturing using ultrafast lasers needs to be developed. This review is focused on the common challenges and current status of the ultrafast laser processing of brittle and hard materials, such as nickel-based superalloys, thermal barrier ceramics, diamond, silicon dioxide, and silicon carbide composites. Firstly, different materials are distinguished according to their bandgap width, thermal conductivity and other characteristics in order to reveal the absorption mechanism of the laser energy during the ultrafast laser processing of brittle and hard materials. Secondly, the mechanism of laser energy transfer and transformation is investigated by analyzing the interaction between the photons and the electrons and ions in laser-induced plasma, as well as the interaction with the continuum of the materials. Thirdly, the relationship between key parameters and ultrafast laser processing quality is discussed. Finally, the methods for achieving highly efficient and high-precision manufacturing of complex three-dimensional micro-components are explored in detail.

Thermal characterization methodology for thin bond-line interfaces with high conductive materials

Silver sintering offers a promising landscape for Pb-free die attachment in electronics packaging. However, the sintered interface properties are highly process-dependent and deviate from bulk silver properties. Conventional measurement methods do not adequately capture the die-attach application geometry. Hence, this study introduces a novel methodology for characterizing thin bond-line interfaces with high-conductive materials. The transient heat flux impedance ΔZth(t, Δx) was measured between two thermally sensitive devices interconnected using pressureless Ag-sintering material. A correction factor was derived, based on thermal half-space principles, to account for non-uniform heat spreading over the die-attach interface. Experimental findings estimate an effective conductivity of ∼115W/mk for the pressureless Ag-sintered interface. The measurement results were validated by measuring a SAC305 soldered interface, which exhibited ∼55 W/mK, and a non-conductive epoxy interface of ∼2.5 W/mK. Voids on the die-attach layer, resulting from material processing, were identified to influence the interface thermal behavior. An uncertainty analysis was further discussed, emphasizing equipment tolerances, measurement sensitivity, and geometrical and thermal anisotropies. The article concludes with a comparative summary of the proposed methodology against conventional methods, highlighting differences in working principle, thickness range, measurement parameters, and their advantages and limitations.

КОМБИНИРОВАННЫЕ ТВОРОЖНО-ОВОЩНЫЕ ЗАПЕКАНКИ ИЗ МЕСТНОГО СЫРЬЯ ДЛЯ РАЦИОНАЛЬНОГО ПИТАНИЯ

The aim of the study is to develop a recipe for combined curd-vegetable casseroles from local raw materials with improved organoleptic and physicochemical properties. A comprehensive study was conducted that allowed theoretically and experimentally substantiating the feasibility of using turnips as a functional ingredient in the preparation of curd-vegetable casserole. The following quality indicators were studied in the experimental samples of culinary products: mass fraction of fat, protein, total sugars, ascorbic acid content; sanitary and microbiological indicators: the number of mesophilic aerobic and facultative anaerobic microorganisms (QMAFAnM), the number of yeast and mold fungi, and coliform bacteria (BGCP). The applied research methods are the mass fraction of fats according to GOST 31902-2012, the mass fraction of protein by the Kjeldahl method according to GOST 10846-91, the mass fraction of ascorbic acid was determined by titration with a solution of sodium 2,6-dichlorophenolindophenolate according to GOST 24556-89, the mass fraction of sugars – by the iodometric method, by diluting the sanitary and microbiolo¬gical indicators of QMAFAnM according to GOST 10444.15-94, counting the colonies of mold fungi and yeast according to GOST 10444.12-2013 and coliform bacteria according to GOST 31747-2012. The study was carried out at the Department of Public Catering Technology and Processing of Plant Raw Materials of the Federal State Budgetary Educational Institution of Higher Education "BashSAU", Republic of Bashkortostan. In the recipe for making cottage cheese and vegetable casserole, carrots were replaced with turnips in a ratio of 25 to 100 %. It was found that 100 % replacement of carrots with turnips in a culinary product improves organoleptic properties (taste, color) and physicochemical indicators (increase in vitamin C by 5.5 times). Sanitary and microbiological indicators (QMAFAnM, coliform bacteria, yeast and mold) corresponded to the required SanPiN 2.3.2.1078-01 standards.

CONTROL OF DEVIATIONS FROM CIRCULARITY WHEN DRILLING POLYMERIC MATERIALS

Polymeric materials represent synthetic macromolecular products, from which objects of various shapes can be manufactured, through mechanical or thermal processing. These materials are used in various industries due to their versatility and ability to adapt to various applications. The paper presents an analysis of deviations from circularity in the drilling process of three types of polymeric materials: PA6 (polyamide), PEHD (high-density polyethylene) and POMC (polyacetal). The main purpose of this analysis is to evaluate and measure the deviations from circularity in the drilled plates using specific drills on the EMCO MILL 55 CNC machine and the precise determination of these deviations is realized with the help of the Sinowon 3D measuring machine. In the context of the processing of polymeric materials, both technical performance criteria and their associated factors in drilling operations are examined. In the study, two types of helical drills were used, with two rectilinear cutting edges, having different diameters, Ø8 mm and Ø10 mm, made of high-speed steel.

Assessment of Surface Roughness of Non-Metallic Materials during Laser Processing

Experimental studies of the surface of non-metallic materials have been carried out to determine the roughness parameters of materials such as leather, bone, wood, plastic after processing the surface of materials with a laser beam. To assess the quality of the surface layer of materials, the depth of penetration of laser radiation into the material, the average value of the micro unevenness, and the mean square deviation of the micro unevenness were used. To describe the changes in the values of the micro unevenness, graphs of the correlation of the parameters of the micro unevenness and the modulus of elasticity of the surface of various non-metallic materials were used. Approximating polynomials are used to describe the correlations with the representation in a computer. A regression model is proposed that relates the properties of the material to the magnitude of the micro unevenness. Data on the depth of ablation for wood, bone, leather, plexiglass are presented, graphs of the correlation between the amount of surface micro unevenness and the density of materials, between the amount of surface micro-roughness and the modulus of elasticity of materials, the correlation coefficient between the amount of surface micro unevenness and the ignition temperature of organic materials. The obtained models make it possible to implement the proposed principle of laser processing of non-metallic materials, which consists in measuring the modulus of elasticity of the surface of the material and, based on the measurements obtained, control the modes of laser processing of products. The installation of laser surface treatment of non-metallic materials with the implementation of the principle of control of processing modes depending on the measured values of the modulus of elasticity of the surface of the material is proposed. To measure the elastic modulus of a material, a special sensor is used with indentation of the indenter and computer evaluation of the measurements obtained with the formation of solutions for controlling the modes of laser surface treatment of the material. The experimental results obtained made it possible to manufacture a number of products to ensure a given surface quality of non-metallic materials (a writing device, a gift for the newlyweds). Conducting experiments with changes in the power of laser radiation based on the results of measuring the modulus of elasticity of the surface of non-metallic materials has shown the effectiveness of operational setting of laser operating modes to ensure the quality of the surface of non-metallic materials.

Повышение ресурсного потенциала древесного сырья

According to the strategy for the development of the forestry complex of the Russian Federation until 2030, approved by Order of the Prime Minister of Russia no. 312r dated February 11, 2021, the contribution of the forestry industry to the country’s economy should increase by 2 times, including through deep wood processing. To this end, enterprises for deep processing of wood raw materials will be actively developed. Consequently, there will be a shortage of wood raw materials, which will lead to an urgent need to expand the raw material base of these industries. Despite this, as the analysis of the practical experience of modern logging enterprises has shown, today, during logging operations, only the stem part of the tree is removed from the cutting area, and the rest of the biomass in the form of stumpwood, branches, twigs and tops is burned or buried, although these parts of the tree are valuable raw materials for the production of many types of products of wood processing enterprises. This state of affairs is due to the lack of effective technology for processing potential raw materials in the places of their formation and a complex of mobile machines for its implementation. As a result, a technology for the production of wood and coniferous flour, technological chips and semi-finished wood-fiber products, as well as mobile equipment for its implementation, has been proposed for the processing of logging waste in the form of tops, branches and twigs. The article presents technological solutions and equipment models built in the SolidWorks computer-aided design system. The introduction of the proposed technologies, machines and mechanisms will increase the share of harvested raw materials per unit area, reduce the environmental load from the logging process, and increase the efficiency of the industry.

Enhancement of Tensile Strength of Coconut Shell Ash Reinforced Al-Si Alloys: A Novel Approach to Optimise Composition and Process Parameters Simultaneously

The research presents a novel approach to develop high-strength functionally graded composite materials (FGCMs) by using recycled coconut shell ash (CSA) particles as reinforcement for a hypereutectic Al-Si alloy matrix. Using a centrifugal casting technique, test specimens are prepared for the study under ASTM standards. The optimal combination of materials to maximise the materials’ overall tensile strength is obtained through the mixture methodology approach. The results show that CSA particles in the matrix material increase the tensile strength of the produced material. Process parameters, melting temperature and rotating speed were found to play a pivotal role in determining the tensile strength. A better tensile strength of the material is obtained when Al-Si = 90.5 wt%, CSA = 9.5 wt%, rotating speed = 800 RPM, and melting temperature = 800 °C; the proposed regression model developed has substantial predictability for tensile strength. This work presents a methodology for enhancing the tensile strength of FGCMs by optimising both the material composition and processing parameters. The achieved tensile strength of 197.4 MPa, at 800 RPM and 800 °C, for a concentration of 7.5 wt% CSA particles, makes these FGCMs suitable for use in multiple engineering sectors.

Large-area magnetic skin for multi-point and multi-scale tactile sensing with super-resolution

The advancements in tactile sensor technology have found wide-ranging applications in robotic fields, resulting in remarkable achievements in object manipulation and overall human-machine interactions. However, the widespread availability of high-resolution tactile skins remains limited, due to the challenges of incorporating large-sized, robust sensing units and increased wiring complexity. One approach to achieve high-resolution and robust tactile skins is to integrate a limited number of sensor units (taxels) into a flexible surface material and leverage signal processing techniques to achieve super-resolution sensing. Here, we present a magnetic skin consisting of multi-direction magnetized flexible films and a contactless Hall sensor array. The key features of the proposed sensor include the specific magnetization arrangement, K-Nearest Neighbors (KNN) clustering algorithm and convolutional neural network (CNN) model for signal processing. Using only an array of 4*4 taxels, our magnetic skin is capable of achieving super-resolution perception over an area of 48400 mm2, with an average localization error of 1.2 mm. By employing neural network algorithms to decouple the multi-dimensional signals, the skin can achieve multi-point and multi-scale perception. We also demonstrate the promising potentials of the proposed sensor in intelligent control, by simultaneously controlling two vehicles with trajectory mapping on the magnetic skin.

Revealing Subsurface Damage Morphology and Patterns in areal Ultrashort Pulse Laser Machining of Glass

Material removal rates as well as surface and subsurface quality are key aspects for the industrial application of ultrashort pulse (USP) laser machining. However, revealing so-called subsurface damage (SSD) is challenging. The presented study visualizes and quantifies subsurface damage patterns in areal USP laser ablation of fused silica (FS) and glass N-BK7 (BK). For the first time, using high-resolution optical coherence tomography (OCT) as non-destructive and three-dimensional (3D) evaluation method, SSD morphologies of areal laser machining induced damages are analysed. Influences of laser wavelength, beam geometry and processed material are investigated. Discovered differences of damage morphologies and depth in FS and BK point out the relevance of selecting suitable process parameters. Based on the evaluation of volumetric OCT data, the authors were able to quantify damage morphologies using the surface texture ratio as well as power spectral density functions. One important finding for the quantification and comparability of damage depths in USP laser processing is the influence of applicable evaluation thresholds. In comparison to area thresholds of 0.001% being applicable to OCT measurements, more lenient thresholds of e.g. 1% commonly applied in destructive SSD measurement methods in average result in a reduction of measured damage depths by a factor of ~ 2. This potentially leads to an underestimation of damage depths depending on methods on thresholds used. The presented measurement and evaluation methods as well as gained process insights are important assets for the future optimization of low-damage USP laser micromachining of brittle materials. Moreover, the general applicability and relevance of OCT-based morphological damage analysis in laser material processing is shown.