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The use of carbon nanotubes (CNTs) in the nanotechnology sector is rapidly increasing due to their distinct characteristics and vast application potential. Large-scale preparation of these nanostructures is either prohibitive or, in some cases, environmentally unfavorable. Numerous studies have been conducted in this field to develop novel approaches for producing CNTs that are savious and cost-effective. This review briefly describes the synthesis, characterization methods, and uses of CNTs from scrap materials. The utilization of waste materials not only addresses environmental concerns but also contributes to the circular economy by repurposing otherwise discarded resources. This eco-friendly approach has several benefits for human health and the environment. [ABSTRACT FROM AUTHOR]

Foamed ceramics with high closed porosity were prepared using granite scrap as the raw material and silicon carbide as a foaming agent, and the effects of Na2O, K2O, and MgO on the pore structure and properties of the foamed ceramics were investigated. The results show that both Na2O and K2O could reduce the viscosity of the melt and promote the formation of the liquid phase, and the increase in content could enhance the foaming ability of the blank. When the dosage of Na2O was 4–6 wt% and the dosage of K2O was 6–8 wt%, the homogeneity of the pore structure of the foamed ceramics could be effectively improved, and the samples exhibited an optimal performance, including a bulk density of 510.36–593.33 kg/m3, a closed porosity of 68.24–78.04%, a compressive strength of 1.33–2.66 MPa, and a water absorption capacity of 0.57–1.31%. A further increase in the Na2O and K2O dosages destroyed the uniformity of the pore structure, resulting in a large number of irregular macropores. MgO had a slight effect on regulating the pore structure of the foamed ceramics, and the increase in dosage promoted the precipitation of forsterite crystals, creating conditions suitable for the preparation of foamed ceramics with small pores. [ABSTRACT FROM AUTHOR]

The investigation of IN718 alloy for aerospace and oil and gas industries focuses on cost-effective component design, specifically for turbines. Manufacturers for IN718 can achieve cost-effectiveness by acquiring recycled materials in the form of scrap. This recycling approach not only addresses economic considerations but also aligns with environmental goals such as reducing greenhouse gas emissions. In the production process, utilizing scrap with higher Si content could reduce costs. However, precise microstructure control is necessary to mitigate microsegregation and secondary phases that impact final product properties. Homogenization treatment minimizes microsegregation, making the alloy suitable for further processing. In this study, as-cast IN718 alloy with 0.2 wt pct Si is homogenized at 1100 °C, 1150 °C, and 1175 °C for 12, 36, 60, and 96 hours. Solute redistribution in as-cast and heat-treated alloys was assessed using SEM-EDS-based area analysis by scanning approximately 2000 uniformly distributed points. The SEM-EDS data analysis yielded concentration profiles for each element in the investigated alloys. Homogenization was determined based on delta values (the difference between maximum and minimum solute concentration) as a function of temperature and time. Homogenization at 1175 °C for 96 hours showed the lowest delta values and is recommended as the suitable heat treatment. Additionally, a diffusion-based homogenization model predicts homogenization extent with respect to temperature and time. The model suggests a two-stage heat treatment: 1150 °C for 25 hours and holding at 1200 °C for 30 hours. [ABSTRACT FROM AUTHOR]

[Display omitted] • Eh-pH diagram of K-S-Fe-H 2 O system is established to analyze the iron removal. • Controlling high potential and a certain pH value are good for jarosite process. • Efficient and selective iron removal from acid solution has been achieved. • Regular ellipsoidal particles of jarosite with even particle size are obtained. • The crystallization mechanism and kinetics of jarosite formation are analyzed. Aerospace magnetic material scraps are abundant in cobalt and nickel. Sulfuric acid leaching process is an efficient method for extracting them. But it is a non-selective process, a significant amount of iron dissolves in the solution. This study focuses on the selective removal of iron from this solution using the jarosite process. E h -pH diagram of K-S-Fe-H 2 O system was established. Based on thermodynamic analysis, H 2 O 2 is used to oxidize Fe2+ into Fe3+, achieving efficient and selective removal of iron from the solution containing cobalt and nickel. The optimal conditions are as follows: temperature 95°C, K 2 SO 4 dosage coefficient 1.5, seed dosage 10 g/L, time 90 min, pH 1.76, and endpoint pH controlled at approximately 3. Under these conditions, the iron removal efficiency is above 99%, while the loss ratios of cobalt and nickel are below 2%. The product is characterized by XRD and SEM-EDS. Results indicate that the product is jarosite ((K,H 3 O)Fe 3 (SO 4) 2 (OH) 6), exhibiting an ellipsoid structure with the mean particle size in the range of 0.2–5.0 μm. Temperature, pH value and seed dosage significantly affect reaction rate, particle size and crystallinity, and K 2 SO 4 dosage mainly affects reaction rate and the morphology of jarosite. The jarosite crystallization kinetics can be described by the Avrami equation, with an Avrami index (n) of approximately 2.5 and the apparent activation energy of 42.68 kJ/mol. [ABSTRACT FROM AUTHOR]

Copyright of Artnodes is the property of Universitat Oberta de Catalunya and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Karaelmas Science & Engineering Journal / Karaelmas Fen ve Mühendislik Dergisi is the property of Karaelmas Science & Engineering Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There has been an increase in the use of high energy photon beam for container scanners in many countries for multi purposes such as detecting high atomic number materials which might be nuclear materials, drugs, high explosive materials and other contrabands etc. High energy photon beams generally 6 and 9 MV can be used for scanning such materials. However, it is important to ensure that radiation level beyond the container scanner installation is within the permissible dose limit specified by the national competent authority for the protection of public and radiation workers. In this paper, challenges in the biological shielding during the installation of high energy X-ray system for scanning vehicles containing suspected materials are discussed. The purpose of the present study is to develop a methodology for shielding design and evaluation for container scanner installations. The basic concept pertaining to shielding evaluation of radiotherapy installations provided in National Council on Radiation Protection and Measurements (NCRP)/International Atomic Energy Agency (IAEA) reports are referred, and appropriately used to calculate optimized shielding thicknesses requirements for container scanner installation. Workload is estimated based on number of containers scanned, machine ON time and dose rate at 1 m. The shielding evaluation includes use of beam stopper in the primary beam, scattering by heterogeneous metallic scrap materials or any other suspected materials contained in the vehicle and their impact on the thickness of shielding walls. A model lay out plan to be used for installation of container scanner is developed. A methodology for shielding evaluation for various protective walls and ceiling of this model is also discussed. The study provides basic requirement for designing a structural room for installing 9MV container scanner from radiological safety view point. [ABSTRACT FROM AUTHOR]

3-D printing systems are essential in contemporary society because they permit instant prototyping. personalized manufacturing of products, and sophisticated geometric patterns. Their function in decreasing scrap material matches with initiatives to promote sustainability, fueling innovations across industries ranging from medicine and aviation to educational institutions and artistic endeavors, which makes them an innovative device driving progress and efficiency in the twenty-first century. It is a gadget that generates three-dimensional items by adding substance layer by layer utilizing a computer design. It is a sort of additive manufacturing technology in which material is placed and solidified to create the finished object. The goal of this study is to offer a comparative overview of the present-day condition of 3-D printing technology with consecutive 3-out-of-5:G robustness strategy for different functioning elements with an emphasis on improvements in approaches, resources. and its several uses, utilizing u-function approach, namely. the universal generating function technique. The present study yielded the reliability function for the proposed system which provides the determination of tail signature. minimal signature, and signature reliability. Furthermore. the system's estimated life and system cost are also assessed. We also evaluate the hazard intensity index for the proposed system. [ABSTRACT FROM AUTHOR]

This study focused on the seismic performance of an intermediate unit of scrap tire–granular material composite columns under cyclic loading. A Laboratory test study regarding the dynamic deformation characteristics of the intermediate unit of a scrap tire–granular material composite column was conducted. The hysteresis loops, skeleton curves, stiffness degradation curves, and energy–dissipation capacities of the three specimens with different initial vertical loads were experimentally evaluated. Based on the test results, a restoring force model of the tire–granular material unit is established. The results demonstrated that the external force had a significant influence on the strength of the intermediate unit of the scrap tire–granular material composite column. The area of the hysteresis loop of the tire–granular material unit was large, indicating a good seismic performance. As the initial vertical load increased, the horizontal bearing capacity and lateral stiffness of the intermediate unit of the scrap tire–granular material composite column increased. The calculation results of the skeleton curve and hysteresis curve were in good agreement with the test results. As a base damping material, the scrap tire–granular material composite column is feasible, and provides a new concept for the resource utilization of the original scrap tire. [ABSTRACT FROM AUTHOR]

• Catalyst-free approach for a technologically advantageous pyrolysis. • Two-stage plant to optimize gas yield (∼65 % w/w) and calorific value (∼41 MJ/kg). • Pyrolytic gas has potential for replacing fossil fuel in combustion engine. • Integration with combustion engine is promising for electricity and thermal power. In response to the escalating global challenge of mounting plastic waste and the imperative to adopt more sustainable practices for resource utilization, our study focuses on the utilization of plastic solid waste (PSW) through a two-stage thermal pyrolysis process. This aims to demonstrate its potential as a high-performance alternative to existing two-stage catalytic pyrolysis methods. The experimentation involved processing real scrap PSW material in a lab-scale batch set-up, emphasizing optimizing residence time in the cracking reactor to maximize gas yield and its lower heating value (LHV). The study underscores the advantages of the employed two-stage thermal pyrolysis apparatus through a comparative analysis with established set-up dedicated to maximizing gas yield. Once the operative conditions were explored, resulting pyrolysis products underwent detailed characterization to assess their suitability as a sustainable fuel source. The study also presents a practical application of the produced gaseous fuel, envisioning its combustion in an internal combustion engine (ICE), known for its flexibility regarding fuel properties. This application is demonstrated through a simulation conducted in Unisim Design©. The successful processing of real PSW material in the two-stage lab-scale experimental set-up showcased optimal gas yield achievements (>65 % w/w) with an LHV (∼41 MJ/kg), comparable to that of natural gas. This emphasizes the potential of these sustainable alternatives to replace fossil fuels, especially in the context of ICE applications. The integration of the pyrolysis plant with an ICE demonstrated promising prospects for generating electricity in the transportation sector and facilitating thermal power for heat integration in pyrolysis reactors. [ABSTRACT FROM AUTHOR]

Rolling is a well-established forming process employed in many industrial sectors. Although highly optimized, process disruptions can still lead to undesired final mechanical properties. This paper demonstrates advances in pass schedule design based on reinforcement learning and analytical rolling models to guarantee sound product quality. Integrating an established physical strengthening model into an analytical rolling model allows tracking the microstructure evolution throughout the process, and furthermore the prediction of the yield strength and ultimate tensile strength of the rolled sheet. The trained reinforcement learning algorithm Deep Deterministic Policy Gradient (DDPG) automatically proposes pass schedules by drawing upon established scheduling rules combined with novel rule sets to maximize the final mechanical properties. The designed pass schedule is trialed using a laboratory rolling mill while the predicted properties are confirmed using micrographs and materials testing. Due to its fast calculation time, prospectively this technique can be extended to also account for significant process disruptions such as longer inter-pass times by adapting the pass schedule online to still reach the desired mechanical properties and avoid scrapping of the material. [ABSTRACT FROM AUTHOR]

This study aims to assess the deflection and elastic modulus (Es) of subgrade in flexible pavements, focusing on a comparative analysis between pavements with clayey soil subgrade and subgrade modified with tire scrap. The research utilized Falling Weight Deflectometer (FWD) for measuring subgrade deflection, essential in evaluating pavement performance. The FWD applied a dynamic load to the pavement, with deflection measurements processed using the KGP-BACK software to calculate the Es of the pavement subgrade. This approach included assessing the Lower Layer Index (LLI) and Es of the subgrade. Findings revealed a notable reduction of 37.5% in deflection and 2.68 times increase in Es for the tire scrap modified subgrade pavement compared to the standard clayey soil subgrade pavement. These results demonstrate significant enhancements in pavement structure, underlining the potential of recycled materials in sustainable civil engineering practices. [ABSTRACT FROM AUTHOR]

Soil thixotropy plays an important role in many engineering practices, which recently has been drawn an increasing attention by many researchers. In this paper, an experimental investigation on the thixotropy of deepwater marine clays in the South China Sea was carried out. The thixotropy-induced changes of undrained shear strength were measured by fall cone method, and the microscale evolution of soil structure, particularly the change of various types of water, was observed and quantified via employing scanning electron microscopy and thermogravimetric analysis, respectively. The test results show that the thixotropy strength ratios of all deep-sea clays increase quickly at the early stage (before about 10 days), then followed by a gradually lower increasing rate with prolonged time. The microstructural evolution of clay during thixotropic hardening is characterized by the transformation from a dispersed structure with parallel-arranged particles to a well flocculated one. The different types of water and their changes of mass fraction with thixotropic time could be well classified and quantitatively measured by thermogravimetric analysis, in which both the weakly and strongly bound water contents decrease, with the corresponding increase in the free water fraction. The thixotropic mechanism was then revealed from the perspective of the microstructural evolution and the adjustment of the thickness of bound water. The recovery of strength is majorly attributed to the forming and strengthening of inter-particle bonds or contacts and the adjustment of bound water layer. This research could help to provide a deeper insight into the inner reason of soil thixotropy. [ABSTRACT FROM AUTHOR]

Thermochemical water splitting is one of the methods to produce green hydrogen. In this study, metal scrap is used to split water by thermochemical process in a packed-bed reactor. Hydrogen production conditions are optimized by varying the particle size of the metal wastes in the range of 250 μm to greater than 1000 μm and the temperatures from 900 °C to 1200 °C. The maximum yield of hydrogen obtained is ∼500 mL of H 2 per gram of the scrap sample. This study demonstrates that the discarded metal wastes can be utilized as feed-materials for thermochemical production of green hydrogen. The process has good conversion efficiency and is a promising solution for both metal waste management and the production of green hydrogen. Medium size metal particles show higher hydrogen production capacity compared to both smaller (<250 μm) and larger (600–1180 μm) size particles. [Display omitted] • Hydrogen production using ferrous metal scrap materials. • Optimum size of ferrous scrap metal particles is in the range of 355–600 μm. • ∼500 mL of green hydrogen produced per gram of ferrous scrap materials at 1100 °C. [ABSTRACT FROM AUTHOR]

Currently green hydrogen production is attracting global attention. In this context, sustainable hydrogen production processes have been explored by using variety of materials and methods. Generation of hydrogen without CO 2 emissions is the key for carbon-free energy economy in future. Enormous amounts of scrap iron, metallurgical wastes and ferrous metals are produced in industrial processes. In this work, the reaction between metal scrap and steam is studied for hydrogen production. The scrap materials are loaded in a packed-bed reactor to produce green hydrogen by water splitting at high temperatures. This method produced 500 mL of green H 2 per gram of scrap material at 1150 °C with a conversion efficiency of about 94%. This is a potential method to utilize the scrap metals for large scale production of green hydrogen without carbon emissions. [Display omitted] • Process of hydrogen production using metal scrap. • Generation of 500 mL of green hydrogen from 1 g of waste-scrap material. • Scalable process for extracting hydrogen from metal-waste. • Maximum hydrogen concentration measured is 924 μL of hydrogen per mL of outlet gas. [ABSTRACT FROM AUTHOR]

Recycling of Nd–Fe–B magnets is an ongoing challenge regarding circular economy. State‐of‐the‐art magnet production methods, such as hot deformation, have limitations with respect to direct recycling of magnet scrap particles that differ from pristine melt‐spun Nd–Fe–B powder. Recent work has shown that a combination of presintering by field‐assisted sintering technology/spark plasma sintering (FAST/SPS) and hot deformation by flash spark plasma sintering (flash SPS) has the potential to directly produce Nd–Fe–B magnets from 100% scrap material. Both processes have the capability to adjust and monitor process parameters closely, resulting in recycled magnets with properties similar to commercial magnets but made directly from crushed and recycled Nd–Fe–B powder that partially or completely replaces pristine melt‐spun Nd–Fe–B powder. Herein, a systematic study is done inserting recycled magnet particles into a flash SPS deformed magnet, considering the effects of different weight percentages of scrap material of varied particle size fractions. In some cases, coercivity HcJ of >1400 kAm−1 and remanence Br of 1.1 T can be achieved with 20 wt% scrap material. The relationship between particle size fraction, oxygen uptake, and percentage of recyclate in a final magnet are all explored and discussed with respect to magnets made from pristine material. [ABSTRACT FROM AUTHOR]

Fabrication industries are emerging to reduce and recycle waste scrap materials into useful products for various engineering applications such as domestic, structural, marine, and construction doors and windows. Most waste scrap materials are affected by soil and water pollution, resulting in unsuitable environmental living. This study is to fabricate the low‐cost and eco‐friendly Al‐ZrO2 alloy composite made with waste Al/Mg metal scrap microparticles through stir casting technique and the developed composite with 0 wt%, 5 wt%, 10 wt%, and 15 wt% of ZrO2 were studied its mechanical properties (ASTM). The synthesized composites' mechanical tensile strength, impact, and hardness were evaluated by ASTM test standard. The revealed experimental results were compared and an optimum sample was addressed. The optical micrograph studies revealed the metal particle presence. The sample 4 composite contained 15 wt% of ZrO2 particles and showed superior mechanical properties like 7.7%, 57.7%, and 13.66% improvement in tensile strength, impact toughness, and hardness compared to sample 1 without ZrO2 particles. [ABSTRACT FROM AUTHOR]

DOES - Dataset of European scrap classes. Today, scrap is already an important raw material for industry. Due to the transformation to green steel, the secondary raw material scrap will become increasingly important in the coming years. With DOES a free dataset is presented, which represents common non-alloyed European scrap classes. Two important points were considered in this dataset. First, scrap oxidizes under normal external conditions and the visual appearance changes, which plays an important role in visual inspections. Therefore, DOES includes scrap images of different degrees of corrosion attack. Second, images of scrap metal (mostly scrap piles) usually have no intrinsic order. For this reason, a technique to extract many overlapping rectangles from raw images was used, which can be used to train deep learning algorithms without any disadvantage. This dataset is very suitable to develop industrial applications or to research classification algorithms. The dataset was validated by experts and through machine learning models. [ABSTRACT FROM AUTHOR]

Escalating scrap tyre generation and its disposal have been of concern as these cause detrimental impacts on the environment. Being a non-biodegradable waste, the possible avenues to discard scrap tyres are limited. This study selectively reviewed published literature to reveal utilization prospects of scrap tyre for the construction of unbound layers of pavement. By substituting conventional materials with scrap tyres, the cost of construction could possibly be reduced. In an attempt, this article reviews the types of soil/aggregates substituted with tyre crumb, size of tyre crumb and substitution amount. Also, engineering properties and their response to the accumulation of tyre crumb are presented. In a nutshell, compaction and strength characteristics worsen at different rates depending on the size of the tyre crumb and soil/aggregate type. On the contrary, hydraulic conductivity and resistance to vibratory forces improved. This kind of cost-effective construction practices benefit economically deprived nations that struggle due to budget constraints pertaining to road infrastructure development and waste disposal. This review would help researchers and practitioners to devise stringent protocols and regularize the usage of scrap tyres in road construction. [ABSTRACT FROM AUTHOR]

Due to decarbonization commitment made by steelmaking companies, the steel industry is tackling a technological transition from blast furnace (BF)–basic oxygen furnace (BOF) route to direct reduction iron (DRI)–electric arc furnace (EAF) route. Under this scenario, ferrous scrap becomes a critical factor for reaching CO2 reduction challenge. However, ferrous scrap can be considered one of the most complex industrial raw materials. In addition, scrap presents a huge heterogeneity in both physical and chemical characteristics. However, for producing high‐quality steel products, certainty on scrap specifics is required. Herein, an artificial intelligent model based on spectral information for the segmentation of different materials contained in the ferrous scrap is proposed. Developed solution offers a processing pipeline through a 2D–3D convolutional neural network algorithm based on a dataset with more than 428 million of pixels through hyperspectral cameras in the 400–1700 nm range. By this model, the detection of ferric fraction, stainless steel, aluminum, zinc, copper, sterile, and rubber and plastic materials are assessed. This work aims at increasing the reliability of the steelmaking process by lowering the number of steel quality noncompliance rejection due to lack of knowledge and uncertainties of these raw material compositions. [ABSTRACT FROM AUTHOR]

The growing demands of magnesium (Mg) based materials had risen new challenges related to disposal of unused parts and a huge amount of waste made by such metals. Attempts to recycle the scrap of these materials through remelting had become one of the preferred choices. However, a series of preliminary steps should be carried out to reduce the impurities as well as to maintain the quality of the casted ingot, for instance, by applying de-coating for removing paints or coating substrates at the scrap surface prior to remelting. In this research, the effects of chemical reagent decoating on the properties of ingot obtained from recycling Mg scrap were studied. A commercial paint removal liquid was preferred as the reagent for removing paint layers over the Mg scrap surface. The de-coated scrap was then remelted in a conventional furnace with NaCl powder as the fluxing layer. The results of this study noticed the importance of chemical de-coating process to reduce the impurity contents in the ingot which might be originated from the coating or paint substrates covering the Mg scrap. Meanwhile, the density and hardness of the Mg ingot processed without de-coating were obviously higher than that had been cleaned previously with paint removing agent. [ABSTRACT FROM AUTHOR]

Motivated by interactions with a major player in the aerospace industry, we consider the relationship between a supplier of specialty material forgings and a buyer that manufactures airplane components by extensively machining down these forgings as per component design specifications. Due to high material removal costs, the buyer prefers these forgings to be as similar in geometry and size to the component as possible, that is, near‐net‐shape. The supplier, by default, is unable to deliver such near‐net‐shape forgings as per technological constraints, but can utilize costly effort and/or invest in the required technologies to achieve such capabilities. By taking into account uncertainty regarding the correspondence between supplier's effort and resulting forging size, we assess the implications of two innovative approaches for improving supply chain performance: (i) input material reduction incentives via contracting and (ii) scrap material recycling. We characterize the optimal decisions with respect to final component geometry, various costs, and which party in the supply chain controls the strategic recycling decision. We find that the supply chain should utilize both approaches in a complementary way for components with complex geometry, yet deliberately limit recycling and eliminate contracting for components with simple geometry—a strategy the buyer always implements when controlling the recycling decision. Furthermore, we show these contracting and recycling strategies to be robust by considering linear, expected cost sharing, and nonlinear contract alternatives. Finally, we study supply chain inefficiencies that result from decentralizing the recycling and/or contracting decisions, and highlight whether expected cost sharing and nonlinear contracts can outperform linear contracts. [ABSTRACT FROM AUTHOR]

Hydrothermal‐based direct regeneration of spent Li‐ion battery (LIB) cathodes has garnered tremendous attention for its simplicity and scalability. However, it is heavily reliant on manual disassembly to ensure the high purity of degraded cathode powders, and the quality of regenerated materials. In reality, degraded cathodes often contain residual components of the battery, such as binders, current collectors, and graphite particles. Thorough investigation is thus required to understand the effects of these impurities on hydrothermal‐based direct regeneration. In this study, we focus on isolating the effects of aluminum (Al) scraps on the direct regeneration process. We found that Al metal can be dissolved during the hydrothermal relithiation process. Even when the cathode material contains up to 15 wt.% Al scraps, no detrimental effects were observed on the recovered structure, chemical composition, and electrochemical performance of the regenerated cathode material. The regenerated NCM cathode can achieve a capacity of 163.68 mAh/g at 0.1 C and exhibited a high‐capacity retention of 85.58 % after cycling for 200 cycles at 0.5 C. Therefore, the hydrothermal‐based regeneration method is effective in revitalizing degraded cathode materials, even in the presence of notable Al impurity content, showing great potential for industrial applications. [ABSTRACT FROM AUTHOR]

To protect our environment, current firms are committed to the circular economy and process maintenance strategies to reduce the waste of resources. In this way, they can also save costs and create an enterprise image and value. Therefore, this study explores an imperfect production system with a circular economy and process maintenance activities, wherein the defective products can be converted into scrap returns (i.e., secondary raw materials) and products can be manufactured using mixed materials containing scrap returns. The proposed system considers multiple products with varying feed rates of scrap returns. According to the scenario of the aforementioned production system, this paper develops a production–inventory model aimed at cost minimization, in which the production run time, purchased quantity of material, number of maintenance times, and recovery rate are decision variables. Furthermore, we also develop a computational algorithm to obtain these optimal solutions efficiently. Finally, the numerical and sensitivity analyses based on a practical case are presented to illustrate the applicability of our method and some managerial implications. For example, both strategies efficiently reduce the total cost per unit time in the proposed numerical example. The sensitivity results can be used to determine the optimal combination of two strategies and the execution moment under various changes in cost parameters. [ABSTRACT FROM AUTHOR]

Aluminum alloys are widely used in the industry thanks to its many advantages such as light weight and high strength. The use of this material in the market is increasing day by day with the developing technology. Due to the high energy inputs in the primary production, the use of secondary ingots by recycling from scrap material are more advantageous. However, the liquid metal quality is quite important in the use of secondary aluminum. It is believed that the quality of recycled aluminum is low, for this purpose, many liquid metal cleaning methods and test methods are used in the industry to assess the melt cleanliness level. In this study, it is aimed to examine the liquid metal quality in castings with varying temperature using K mold. A206 alloy was used, and the test parameters were selected as: (i) at 725 °C, 750 °C and 775 °C casting temperatures, (ii) different hydrogen levels. The hydrogen level was adjusted as low, medium and high with degassing, as-cast, and upgassing of the melt, respectively. The liquid metal quality of the cast samples was examined by the K mold technique. When the results were examined, it was determined that metal K values and the number of inclusions were high at the as-cast and up-gas liquid with increasing casting temperatures. It has been understood that the K mold technique is a practical method for the determination of liquid metal quality, if there is no reduced pressure test machine available at the foundry floor. [ABSTRACT FROM AUTHOR]

This paper defines terms such as "recycling rate" that enable the characterization of flows of battery materials and expands the terminology to accommodate the description of complex product recycling. It also estimates the maximum percentage of U.S. demand for critical elements that could be satisfied by recycling as demand continues to grow, and it defines and estimates the recycling rate for lithium-ion batteries. Finally, it clarifies the role of manufacturing scrap as the domestic U.S. supply chain is built up. It concludes that recycling will be important in the long term, but growth still requires that new material be extracted to supply additional material. [ABSTRACT FROM AUTHOR]

The transformation toward electromobility presents a significant challenge to the battery cell production processes. It is, therefore, necessary to establish efficient and robust operations and machines to meet the forecasted demand for manufactured cell capacity. Currently, the development and ramp‐up phases of production machines, especially for cell stack assembly, are characterized by high material scrap rates and large personnel expenses. Aspects such as the web tension of electrodes or separator materials during separation and stack assembly have a significant influence on the subsequent intermediate product properties, and therefore present a key challenge. Herein, the optimal methodology for the web tension control of electrode materials is determined via a model‐based approach by the means of a digital twin. The focus is hereby set on a production machine for the flexible cell stack assembly. Appropriate control methods are implemented and validated on the real system, thus reducing material scrap rates and overall costs. The control of the web tension by means of an unwinder and material storage was found to be optimal on the basis of the model and confirmed experimentally. [ABSTRACT FROM AUTHOR]

The objective of the presented work was to develop a new forging process for a pinion shaft as a component of a wind turbine. A study of near-net-shape forming using Deform 3D software was performed to reduce operational cost, time, and material scrap; enhance specific properties; increase productivity. Near-net forged products have good dimensional accuracy and continuous metal flow lines, which are characteristic of improved mechanical properties. To avoid the traditional trial-and-error experimental method, the process and tool design were accomplished with a careful and detailed numerical simulation approach. In the present work, the Finite Element Method was used to develop a process model for the existing hot forging process of the 18CrNiMo7-6 steel pinion shaft used in a wind turbine. The developed numerical process model was validated via experiment including a comparison of the metal flow lines from the FEM model with the metallography results of the forged part. Two new die designs were proposed, and the simulation results were compared to the actual process to achieve improved geometry. The results for the new geometries showed improvements in terms of the die cavity filling for the new proposed dies and better results in grain flow orientation. Compared to the initial non-optimized die, the new designs improved the mechanical properties and savings associated with the lower volume of required raw material and fewer finishing operations. Considering the applied stresses and wear in the new near-net shape, the die geometry shall be updated to accommodate more severe solicitations. Naturally, all the improvements carried out are dependent on other factors such as the conditions of the equipment, operator skills, lubrication, and other variables. A surface heat treatment is also suggested for stress relief as a reliability improvement. [ABSTRACT FROM AUTHOR]

Decolonisation has recently captured the attention of those who inhabit South African universities, mainly sparked by student protests of 2015 and 2016. In this article writing is used as a mode of inquiry to explore what it means to decolonise the university in a contemporary world that is confronted with crises of all kinds; political, economic, environmental, health, education, and so forth. A third world university is pitted against a first world university (the neoliberal university that accumulates) and a second world university (the university that critiques), not as a new utopian idea but as a university that scavenges on the scrap material of the first and second world universities to retool them for decolonial purposes. In doing so the article changes the angle of vision on decolonising the university in South Africa and elsewhere. The author thinks with la paperson's ideas including hir notion of scyborg, which refers to people who use their agency to retool material of the first and second world universities to garner decolonial desires. A third possibility for the university jettisons the idea of a totalizing, utopian, decolonised university. What is possible is that the university can operate like a decolonised university, without being disengaged from the first and second world universities, signifying new ways of thinking/doing research, teaching, learning and community engagement. [ABSTRACT FROM AUTHOR]

The article provides understanding of the root causes of poor material quality in production in order to increase efficiency and minimize loss of revenue due to rework, scrap and return merchandise authorization (RMA). Topics discussed include importance of process controls around materials handling, risk of purchasing from stockists, the need to evaluate expired materials before purchase, responsibility of engineers to investigate the manufacturing process, and supplier selection process.

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Ultra‐high molecular weight polyethylene (UHMWPE) is one of the most prominent high‐performance thermoplastics for biomedical, leisure, and coating applications. Large‐scale recycling of UHMWPE is extremely difficult due to the high melt viscosity of the material as well as its exceptional chemical resistance and impact strength. There is a need for a commercially scalable methodology that can process the waste feedstock for mechanical recycling while sustaining the outstanding physical properties of the material. Solid‐state shear pulverization (SSSP) is a continuous, twin‐screw extruder‐based processing technique in which the low‐temperature application of shear and compressive forces impart changes in structure at different length scales to overcome the challenges of difficult‐to‐recycle polymers. This paper investigates the use of SSSP in mechanically recycling post‐industrial scrap UHMWPE (rUHMWPE) material from a local ski and snowboard manufacturer. The SSSP‐processed particles are flat, micron‐scale flakes with enhanced surface area, which can sinter very quickly when compression molded. The molded rUHMWPE samples in turn exhibit enhanced ductility and toughness compared to the as‐received scrap material, based on the tunable mechanochemical modification of the ethylene chains. [ABSTRACT FROM AUTHOR]

[Display omitted] • Study on total monetary value and mass of all debris objects currently in orbit. • Method uses authoritative data from European Space Agency's DISCOS dataset. • High estimate for reuse of $1.2 trillion; median/low estimates of $600/$570 billion. • Scrap material: high/median/low mass estimates of 19,124 / 6,978 / 5,312 tonnes. • Development of in-orbit services crucial to viability of circular economy for space. The orbital debris population is rapidly growing, increasing the chance of a Kessler-style collision event. We report a novel method for the production of estimates for the total monetary value of all debris objects and total mass of all objects currently in orbit. The method was devised using debris object data from the European Space Agency's DISCOS dataset, classified via a decision tree. 'Reuse' and 'scrap material' scenarios were developed. A high-end estimate for reuse shows a net value of $1.2 trillion. Median and low-end net value estimates of $600 billion and $570 billion, respectively, are probably judicious. A scrap material scenario produced a high mass estimate of 19,124 tonnes, a median of 6,978 tonnes and a low estimate of 5,312 tonnes. Development of in-orbit services will be crucial to solve the orbital debris problem. A future circular economy for space may be financially viable, with potentially beneficial consequences for risk reduction; resource efficiency; additional high-value employment; and climate-change knowledge, science, monitoring and early warning data. [ABSTRACT FROM AUTHOR]

In the separation of scrap metal based on dual-energy X-ray transmission technology, the recognition effect is largely affected by the features of the selected materials. The features used in the existing scrap metal material recognition algorithms are not comprehensive enough, and the redundancy among feature data is large, so the recognition accuracy is not high. To solve this problem, this paper gives full consideration to the redundancy between features and the correlation between features and categories, and puts forward a correlation-based feature selection method(CFS) to determine the optimal feature subset consisting of features IH, IL, x TML and TMH among many material features. Comparative experiments were carried out by using different material feature combination methods, and K nearest neighbor (KNN) under the optimal feature subset was selected as the optimal classification model. The experimental results show that; compared with the existing classification methods, the identification and classification method of waste nonferrous metals materials based on the correlation-based feature selection and K nearest neighbor (CFS-KNN) has higher identification accuracy (96.13%) with relatively few features. [ABSTRACT FROM AUTHOR]