Search Results (144)

As the use of data models and data science techniques in industrial processes grows exponentially, the question arises: to what extent can these techniques impact the future of manufacturing processes? This article examines the potential future impacts of these models based on an assessment of existing trends and practices. The drive towards digital-oriented manufacturing and cyber-based process optimization and control has brought many opportunities and challenges. On one hand, issues of data acquisition, handling, and quality for proper database building have become important subjects. On the other hand, the reliable utilization of this available data for optimization and control has inspired much research. This research work discusses the fundamental question of how far these models can help design and/or improve existing processes, highlighting their limitations and challenges. Furthermore, it reviews state-of-the-art practices and their successes and failures in material process applications, including casting, extrusion, and additive manufacturing (AM), and presents some quantitative indications. Full article

Phonolite is a fine-grained, shallow extrusive rock rich in alkali minerals and containing iron/titanium-bearing minerals. This rock is widely used as a construction material for building exteriors due to its excellent abrasion resistance and insulation properties. However, during the cutting process, approximately 70% of the rock is discarded as tailing. So, this study aims to repurpose tailings from a phonolite cutting and sizing plant into a high-alkali ceramic raw mineral concentrate. To enable the use of phonolite tailings in ceramic manufacturing, it is necessary to remove coloring iron/titanium-bearing minerals, which negatively affect the final product. To achieve this removal, dry/wet magnetic separation processes, along with flotation, were employed both individually and in combination. The results demonstrated that using dry high-intensity magnetic separation (DHIMS) resulted in a concentrate with an Fe₂O₃ + TiO₂ grade of 0.95% and a removal efficiency of 85%. The wet high-intensity magnetic separation (WHIMS) process reduced the Fe₂O₃ + TiO₂ grade of the concentrate to 1.2%, with 70% removal efficiency. During flotation tests, both pH levels and collector concentration impacted the efficiency and Fe₂O₃ + TiO₂ grade (%) of the concentrate. The lowest Fe₂O₃ + TiO₂ grade of 1.65% was achieved at a pH level of 10 with a collector concentration of 2000 g/t. Flotation concentrates processed with DHIMS achieved a minimum Fe₂O₃ + TiO₂ grade of 0.90%, while those processed with WHIMS exhibited higher Fe₂O₃ + TiO₂ grades (>1.1%) and higher recovery rates (80%). Additionally, studies on flotation applied to WHIMS concentrates showed that collector concentration, pulp density, and conditioning time significantly influenced the Fe₂O₃ + TiO₂ grade of the final concentrate. Full article

The incorporation of solid particles as a filler to a hydrogel is a strategy to modulate its properties for specific applications, or even to introduce new functionalities to the hydrogel itself. The efficacy of such a modification depends on the filler content and its interaction with the hydrogel matrix. In drug delivery applications, solid particles can be added to hydrogels to improve drug loading capacity, enable the inclusion of poorly soluble drugs, and modulate release kinetics. This work focuses on the case of alginate (ALG)-based hydrogels, obtained following an internal gelation procedure using CaCO₃ as the Ca²⁺ source and containing a high solid volume fraction (up to 50%) of metronidazole (MTZ), a drug with low water solubility, as a potential extrusion-based drug delivery system. The impact of the hydrogel precursor composition (ALG and MTZ content) on the rheological behavior of the filled hydrogel and precursor suspension were investigated, as well as the hydrogel stability and MTZ dissolution. In the absence of solid MTZ, the precursor solutions showed a slightly shear thinning behavior, more accentuated with the increase in ALG concentration. The addition of drugs exceeding the saturation concentration in the precursor suspension resulted in a substantial increase (about one order of magnitude) in the low-shear viscosity and, for the highest MTZ loadings, a yield stress. Despite the significant changes, precursor formulations retained their extrudability, as confirmed by both numerical estimates and experimental validation. MTZ particles did not affect the crosslinking of the precursors to form the hydrogel, but they did control its viscoelastic behavior. In unfilled hydrogels, the ALG concentration controls stability (from 70 h for the lowest concentration to 650 h for the highest) upon immersion in acetate buffer at pH 4.5, determining the MTZ release/hydrogel dissolution behavior. The correlations between composition and material properties offer a basis for building predictive models for fine-tuning their composition of highly filled hydrogel systems. Full article

We designed detachable steel sleeves to reinforce wooden joints and improve their integrity under earthquake action and investigated their mechanical properties. Monotonic bending tests were performed on a half-tenon pure wooden joint and a joint strengthened by a detachable steel sleeve. More obvious tenon pulling-out failure was observed in the pure wood joint; in comparison, only slight extrusion fracture of wooden beams and extrusion deformation of steel sleeves occurred in the wood joint reinforced by a detachable steel sleeve. Our test results showed that the initial rotational stiffness of the strengthened joint, JG1, was increased by 495.4% compared with that of the unstrengthened joint, JG0. The yield bending moment increased by 425.9%, and the ultimate bending moment increased by 627.5%, which indicated that the mechanical performance was significantly improved when the joint was reinforced by a detachable steel sleeve. Numerical simulations of different components were performed with finite element analysis software to analyze the mechanical performance of the reinforced joint. It was found that the stiffness and ultimate flexural performance of the joint could be increased by setting stiffeners on the steel sleeve and connecting the wooden column with self-tapping screws. The results of the tests were compared with those obtained through finite element analysis, and a high degree of accuracy was achieved, which could provide a theoretical basis for the reinforcement of timber structural buildings. Full article

In the context of accelerated urbanization and ageing in China, the inefficient use of land resources and ecological space extrusion pose significant challenges to the development of age-friendly cities. Existing studies predominantly adopt a single-disciplinary perspective, and there is a paucity of systematic exploration of regional heterogeneity and the multidimensional influencing mechanisms of the effects of adaptive land management policies. Drawing upon the theoretical framework of social-ecological system resilience in environmental sociology, this study integrates the concept of adaptive land management as a factor in the resilience of old-age-friendly cities. Empirical investigation is conducted to examine the impact of adaptive land management on the resilience of old-age-friendly cities and its spatial differentiation. The entropy weight method and the panel regression model are utilized to analyze the panel data of 269 prefectural-level cities in China from 2010 to 2022. The study posits that effective land management is instrumental in enhancing the resilience of age-friendly cities through optimal spatial allocation and ecological restoration. The promotion effect is more pronounced in the central and western regions and in small and medium-sized cities. The internal dimensions of resilience demonstrate heterogeneity, with economic and social resilience showing significant improvement, and ecological resilience being constrained by natural thresholds with a limited effect. The study also puts forward policy recommendations for further building the resilience of age-friendly cities. Full article

Innovations in additive manufacturing (AM) methods represent a significant advancement in manufacturing technology, opening new avenues for creating objects in various shapes and sizes. Fused deposition modeling (FDM) is a specialized AM technique in which computers build layers upon each other to form a complete 3D object. The feasibility of producing metal parts using these methods has been thoroughly analyzed, but the design process has yet to catch up with manufacturing capabilities. Biodegradable aliphatic polyester PLA is derived from lactic acid. To enhance its strength, PLA is combined with metal particles, resulting in versatile property improvements and applications. While the aesthetic and functional qualities of PLA–metal composite filaments are intriguing, they also present difficulties related to extrusion, equipment wear, and maintaining consistent print quality. These challenges could be mitigated, to some extent, with careful tuning and specialized hardware. However, the inferior mechanical properties of bioresorbable PLA filaments highlight the need for the development of infilled PLA filaments to improve strength and other characteristics. This review discusses the 3D printing of PLA infilled with metal particles, various materials used, and their properties as a matter of interest in AM technology. Additionally, the applications of PLA–metal composites, along with their implications, limitations, and prospects, are comprehensively examined in this article. This sets the stage for the development of high-strength, sustainable materials for use in a range of engineering and technology fields. Full article

Lateral flow tests (LFTs) had a pivotal role in combating the spread of the SARS-CoV-2 virus throughout the COVID-19 pandemic thanks to their affordability and ease of use. Most of LFT devices were based on nitrocellulose membrane strips whose industrial upscaling to billions of devices has already been extensively demonstrated. Nevertheless, the assay option in an LFT format is largely restricted to qualitative detection of the target antigens. In this research, we surveyed the potential of UV nanoimprint lithography (UV-NIL) and extrusion coating (EC) for the high-throughput production of disposable capillary-driven, foil-based tests that allow multistep assays to be implemented for quantitative readout to address the inherent lack of on-demand fluid control and sensitivity of paper-based devices. Both manufacturing technologies operate on the principle of imprinting that enables high-volume, continuous structuring of microfluidic patterns in a roll-to-roll (R2R) production scheme. To demonstrate the feasibility of R2R-fabricated foil chips in a point-of-care biosensing application, we adapted a commercial chemiluminescence multiplex test for COVID-19 antibody detection originally developed for a capillary-driven microfluidic chip manufactured with injection molding (IM). In an effort to build a complete ecosystem for the R2R manufacturing of foil chips, we also recruited additional processes to streamline chip production: R2R biofunctionalization and R2R lamination. Compared to conventional fabrication techniques for microfluidic devices, the R2R techniques highlighted in this work offer unparalleled advantages concerning improved scalability, dexterity of seamless handling, and significant cost reduction. Our preliminary evaluation indicated that the foil chips exhibited comparable performance characteristics to the original IM-fabricated devices. This early success in assay translation highlights the promise of implementing biochemical assays on R2R-manufactured foil chips. Most importantly, it underscores the potential utilization of UV-NIL and EC as an alternative to conventional technologies for the future development in vitro diagnostics (IVD) in response to emerging point-of-care testing demands. Full article

Additive manufacturing brings many benefits to the building industry, one of them being automatization and the possibility to work in harsh environments, including underwater applications. In addition, this technology enables faster infrastructure repairs and adjustments to the scope of work to specific damage caused by, for example, biocorrosion processes. The main aim of this article is to investigate the development of geopolymers as a printable material for civil engineering, including underwater applications. For that purpose, the process of the material extrusion will be modified, and material properties will be improved. In the first step, the raw materials were investigated (SEM, EDS, XRF, particle size analysis) and the proper additives were selected based on literature analysis. Next, geopolymer paste was synthesized and fresh paste properties were investigated, including time for curing samples and workflow. The mixture composition was modified to obtain the required printable parameters through the application of different additives and the modification of the proportion of components, especially alkali solution. Finally, small-scale additive manufacturing trials were conducted in the air and with submerged containers. Additionally, samples were prepared using the casting method to compare the mechanical properties and microstructure. The obtained results show that additives such as xanthan gum and superplasticizer improve the rheological properties of the paste efficiently. With the help of additive manufacturing, geopolymer samples with compressive strengths of up to 7.5 MPa and flexural strengths of up to 4.15 MPa after 28 respectively were achieved. Compared to the average of the cast samples, the compressive strength of the printed samples was at least 5% lower, while the flexural strength was at least 38% lower for printed samples. The 3D-printed samples showed strong anisotropy between the tested orientations of the flexural strength samples. Full article

The increasing global demand for metals, driven by technological progress and the energy transition, has led to an acceleration in the expansion of the mining and metallurgical industry, resulting in an increase in the generation of mine tailings. This waste, which is of heterogeneous composition and has high contaminant potential, represents significant environmental and social challenges, affecting soils, water, and the geotechnical stability of tailings. The accumulation of these mine tailings poses a problem not only in terms of quantity, but also in terms of physicochemical composition, which exacerbates their environmental impact due to the release of heavy metals, affecting ecosystems and nearby communities. This article reviews the potential of geopolymerization and 3D printing as a technological solution for the management of tailings, offering an effective alternative for their reuse as sustainable building materials. Alkaline activation of aluminosilicates facilitates the formation of N–A–S–H and C–A–S–H cementitious structures, thereby providing enhanced mechanical strength and chemical stability. Conversely, 3D printing optimizes structural design and minimizes material consumption, thereby aligning with the principles of a circular eco-economy and facilitating carbon footprint mitigation. The present study sets out to compare different types of tailings and their influence on geopolymer reactivity, workability, and mechanical performance. In order to achieve this, the study analyses factors such as the Si/Al ratio, rheology, and setting. In addition, the impact of alkaline activators, additives, and nanoparticles on the extrusion and interlaminar cohesion of 3D printed geopolymers is evaluated. These are key aspects of their industrial application. A bibliometric analysis was conducted, which revealed the growth of research in this field, highlighting advances in optimized formulations, encapsulation of hazardous waste, CO₂ capture, and self-healing geopolymers. The analysis also identified technical and regulatory challenges to scalability, emphasizing the necessity to standardize methodologies and assess the life cycle of materials. The findings indicated that 3D printing with tailings-derived geopolymers is a viable alternative for sustainable construction, with applications in pavements, prefabricated elements, and materials resistant to extreme environments. This technology not only reduces mining waste but also promotes the circular economy and decarbonization in the construction industry. Full article

The accumulation of plastic waste poses a significant environmental challenge, necessitating sustainable solutions. This study investigates the potential of recycling waste plastics for use in the construction industry, emphasizing their integration into building materials and components. Earlier waste plastic recycling was excessively studied as an ingredient in concrete composites, roads, and other use in research. However, in this study, recycled plastic is assessed for use as a sole material for structural products. Raw plastics, including high-density polyethylene, Low-Density Polyethylene, polypropylene, polyolefin, samicanite, and virgin polyethylene, were analyzed for recycling through mechanical extrusion, and their mechanical properties were analyzed to determine their feasibility for construction applications. In this study, the extrusion process, combined with engineered dyes, was investigated with comprehensive material testing as per the ASTM standards to obtain the properties desired for construction. Advanced characterization techniques, including SEM, FTIR, and TGA, were employed to evaluate the chemical composition, thermal stability, and impurities of these waste plastics collected from municipal waste. A gas emission analysis during extrusion confirmed a minimal environmental impact, validating the sustainability of the recycling process. Municipal waste plastic has a considerable quantum of HDPE, PP, and LDPE, which was considered in this research for recycling for construction products. A total of 140 samples were recycled through extrusion and tested across shear, flexural, tensile, and compression categories: 35 samples each. The results showed that rHDPE and PP had good tensile strength and shear resistance. The findings pave the way for developing cost-effective, durable, and eco-friendly building materials, such as rebars, corrugated sheet, blocks, and other products, contributing to environmental conservation and resource efficiency for the construction Industry. Full article

Challenges in the traditional cast-and-cure manufacturing of composite solid propellants, such as the use of mandrels and the toxicity of curing agents, are being addressed through new propellant formulations and additive manufacturing techniques. Within this framework, this study aimed to investigate the properties of UV-curable composite solid rocket propellants, focusing on their compatibility with advanced 3D printing technologies. Polybutadiene-based propellants incorporating a specific photoinitiator were examined. Key rheological properties, including the pseudoplasticity and pot-life, were assessed to evaluate the material’s behavior during the printing process. Furthermore, photopolymerization tests were performed using a customized delta illuminator to evaluate the conversion efficiency under UVA and UVC light sources. Concurrently, a modular Cartesian 3D printer was developed and preliminary tests were performed. Rheological tests also revealed a flow index n of 0.32 at 60 °C and 0.46 at 80 °C, indicating significant pseudoplastic behavior. The pot-life tests showed that the viscosity of the propellant reached the upper limit of ${10}^6$ cP more quickly at higher temperatures, indicating a shorter time range of printability. UVA irradiation resulted in a polymerization conversion rate of about 90%, while UVC exposure did not significantly enhance the conversion rate beyond this value. Finally, the 3D printing tests confirmed the feasibility of producing solid propellant, though challenges related to material segregation and the extrusion consistency were observed. Material separation resulted in a significant impact on the printability, causing underextrusion and nozzle clogging, particularly with smaller nozzle diameters and higher extrusion pressures. Overall, this research represents a significant step forward in the development of UV-curable propellants for additive manufacturing, building on previous advancements by the research group. It demonstrates tangible progress in addressing key challenges such as the printability, material performance, and curing efficiency, while also highlighting areas requiring further refinement. These findings underscore the continuous evolution of this technology toward higher readiness levels, paving the way for its broader application in composite solid propellant manufacturing. Full article

Additive manufacturing (AM) is an emerging technology with the greatest potential impact on many engineering applications. Among the AM technologies, material extrusion is particularly interesting for plastic components due to its versatility and cost-effectiveness. There is, however, a limited knowledge of design methods to predict the mechanical strength of parts built by material extrusion. The materials are polymers, sometimes also reinforced, and deposited in layers like in laminated composites. Therefore, the mechanical behavior and strength can be characterized and modeled with methods already known for composite materials. Such tools are the classical lamination theory (CLT) and the failure criteria for composites. This paper addresses an analysis of a composite material made of long-fiber glass in a polyamide matrix built by additive manufacturing; in this relatively new technique, a continuous fiber is inserted between layers of polyamide deposited from a wire with a fused filament fabrication (FFF) 3D printer. The mechanical behavior was studied from tensile tests that were carried out to demonstrate the feasibility of modeling with the mentioned tools, and the material properties for predicting the stiffness and strength of components built with that technique were identified. The results show that the classical models for the mechanical behavior of composite materials are well-suited for this material to predict the influence of the main building parameters. Full article

Integrating LiDAR and photogrammetry offers significant potential for ensuring the accuracy and completeness of the 3D models of existing structures, which are essential for several applications in the architectural, engineering, and construction (AEC) industry. This study has two primary objectives: the first is to demonstrate how LiDAR and photogrammetry complement each other, through the balance of LiDAR’s structural accuracy with photogrammetry’s rich texture data; the second is to validate the quality of the resulting mesh by using it for the CFD simulation of wind flow around a case study building. The integration method, though simple, is optimized to ensure high-quality point cloud registration, minimizing data quality impacts. To capitalize on the advantages of both manual and full point-cloud-based modeling methods, the study proposes a new hybrid approach. In the hybrid approach, the large-scale and simplified parts of the geometry are modeled manually, while the complex and detailed parts are reconstructed using high-resolution point cloud data from LiDAR and photogrammetry. Additionally, a novel region of constraints method (ROCM) is introduced to streamline wind flow simulations across varying scenarios without the need for multiple meshes. The results indicate that the integrated approach was able to capture the complete and detailed geometry of the case study building, including the complex window extrusions. The CFD simulations revealed differences in the wind flow patterns and pressure distributions when compared across different geometry modeling approaches. It was found that the hybrid approach is the best and balances efficiency, accuracy, and computational cost. Full article

The quality, reproducibility, and reliability of additive-manufactured parts strongly depend on optimizing printing parameters and post-processing treatments. This study evaluates the effects on the microstructure and corrosion resistance properties of solution annealing and aging heat treatments performed on 17-4 PH stainless steel samples fabricated with different build-up orientations using a material extrusion technology: the Bound Metal Deposition^TM. The chemical composition and microstructures were determined using X-ray diffraction, chemical etching, optical microscopy, and scanning electron microscopy. The corrosion resistance properties in neutral sodium chloride electrolytes were investigated through cyclic potentiodynamic polarization and open circuit potential monitoring and analysis. The findings demonstrated that the solution annealing heat treatment remarkably enhanced the overall corrosion resistance properties of the samples. The improvement was attributed to the growth of the ferritic phase along the grain boundaries of the martensitic matrix and a finer dispersion of copper precipitates. The aging heat treatment performed after solution annealing enhanced the ferritic phase development, resulting in a further improvement of the localized corrosion resistance properties. Full article

New data science and real-time modeling techniques facilitate better monitoring and control of manufacturing processes. By using real-time data models, industries can improve their processes and identify areas where resources are being wasted. Despite the challenges associated with implementing these data models in transient and multi-physical processes, they can significantly optimize operations, reduce trial and error, and minimize the overall environmental footprint. Implementing real-time data analytics allows industries to make quicker, informed decisions and immediate corrections to material processes. This ensures that manufacturing sustainability targets are regularly met and product quality is maintained. New concepts such as digital twins and digital shadows have been developed to bridge the gap between physical manufacturing processes and their virtual counterparts. These virtual models can be continuously updated with data from their physical counterparts, enabling real-time monitoring, control, and optimization of manufacturing processes. This paper demonstrates the predictive power of real-time reduced models within the digital twin framework to optimize process parameters using data-driven and hybrid techniques. Various reduced and real-time model-building techniques are investigated, with brief descriptions of their mathematical and analytical foundations. The role of machine learning (ML) and ML-assisted data schemes in enhancing predictions and corrections is also explored. Real-world applications of these reduced techniques for extrusion and additive manufacturing (AM) processes are presented as case studies. Full article