•Mapped and analyzed the level of automation of aerospace composite manufacturing process chains.•Current ‘Automated’ process chains have not reached the higher level of automation expected in ...Industry 4.0.•Highlights areas for improvements in automating non-value-added activities and core-process tasks.•Provides future directions towards a smart composite factory in the context of Industry 4.0.
Composites have become the go-to material of the aerospace industry during the past decades and a significant uptake in composite materials for aerospace applications was evident in recent years. Both expert academics and industry practitioners believe, to meet the future demand, the level of automation in the aerospace composite manufacturing process chains must be improved. The main focus of automation in composites so far has been given to automate siloed operations but limited attention has been paid to end-to-end integration of the process chains leading to inefficiencies, rising operational costs, and low productivity. This paper intends to compare and contrast the level of automation (LOA) in different aerospace composite manufacturing process chains to identify where the LOA triumphs and lacks. For this purpose, core-process and sub-process tasks involved in commonly used manufacturing process chains (i.e. Filament Winding, Automated Tape Layup, Automated Fiber Placement, Resin Transfer Molding, and Pultrusion) are identified by conducting a detailed literature review and verified by the experts. Then, the process chains are mapped and visualized to understand the workflow. Later, these tasks are evaluated based on an established LOA taxonomy developed for manufacturing processes. The study reveals that even the popular ‘automated’ processes are developed in silos and do not show consistent higher LOA throughout their process chain. While core-process tasks show intermediate LOA (Level 5–6), most non-value-added activities show poor LOA (Level 1–4). Most importantly, none of the tasks involved in the existing composite manufacturing process chains have reached a higher LOA (Level 7). The paper reveals that focusing on sub-process tasks, and tasks that lack automation should be the next step towards achieving fully automated composite manufacturing and presents a two-pronged approach to realize Industry 4.0.
The potential for recycling of carbon fibre reinforced epoxy composites in water at supercritical or nearcritical conditions was studied. Experiments were devised in order to identify the significant ...process parameters that affect fibre reinforced composite recovery potential including temperature, time, oxidant and catalyst concentration. Experiments were performed in a batch-type reactor (10
mL) without stirring, with temperatures ranging from 523 to 673
K, pressures from 4.0 to 27.0
MPa and reaction times from 1 to 30
min. The efficiency of resin removal reached ca. 79.3
wt.% under supercritical water conditions with further improvement through the use of potassium hydroxide as alkali catalyst (up to 95.3
wt.%). The tensile strength of the reclaimed fibres was between 90% and 98% than that of the virgin fibres. A second-order kinetic equation was implemented to model the reactive extraction process.
•A novel low temperature loading method is proposed to prepare Pt/CN+SAPO-11 catalysts.•The method provides catalysts with smaller particle sizes and higher dispersion.•Low temperature loading method ...results in both single atoms and metal clusters within the catalyst.•The electron density of PT increased after loading on g-C3N4 support contributing to enhanced catalytic activity.•The catalyst shows a significant increase in hydroisomerization activity and selectivity compared to those prepared with the traditional method, with an isomer yield of up to 68.2 %.
Bifunctional catalysts, consisting of metal and acid sites, can be applied in the alkane hydroisomerization reaction, and the process of dehydrogenation and hydrogenation at the metal sites can balance the isomerization and cracking routes, carbocation rearrangement at acidic sites affecting the hydroisomerization performance. Metals are traditionally prepared at high temperature which results in metal agglomeration. To address this drawback, a low-temperature method for catalyst loading is proposed. The method provides catalysts with smaller particle sizes and higher dispersion to prevent metal agglomeration. Specifically, when the loading capacity of metal Pt is 0.3 wt%, this method results in both single atoms and metal clusters within the catalyst. And the catalyst shows a balanced metal-acid function once capacity for Pt loading increased to 0.5 wt%. Moreover, the electron density of Pt following metal loading on g-C3N4 support increased, and the turnover frequency (TOF) of each metal site also increased with the rise of nPt/nA. Furthermore, it is noted that the catalyst prepared by low-temperature loading shows significant increased hydroisomerization activity and selectivity compared to those prepared with the traditional method, with an isomer yield of up to 68.2 %.
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Centratherum anthelminticum (L.) seeds (CA) is a well known medicinal herb in Indian sub-continent. We recently reported anti-oxidant property of chloroform fraction of Centratherum anthelminticum ...(L.) seeds (CACF) by inhibiting tumor necrosis factor-α (TNF-α)-induced growth of human breast cancer cells. However, the active compounds in CACF have not been investigated previously.
In this study, we showed that CACF inhibited growth of MCF-7 human breast cancer cells. CACF induced apoptosis in MCF-7 cells as marked by cell size shrinkage, deformed cytoskeletal structure and DNA fragmentation. To identify the cytotoxic compound, CACF was subjected to bioassay-guided fractionation which yielded 6 fractions. CACF fraction A and B (CACF-A, -B) demonstrated highest activity among all the fractions. Further HPLC isolation, NMR and LC-MS analysis of CACF-A led to identification of vernodalin as the cytotoxic agent in CACF-A, and -B. 12,13-dihydroxyoleic acid, another major compound in CACF-C fraction was isolated for the first time from Centratherum anthelminticum (L.) seeds but showed no cytotoxic effect against MCF-7 cells. Vernodalin inhibited cell growth of human breast cancer cells MCF-7 and MDA-MB-231 by induction of cell cycle arrest and apoptosis. Increased of reactive oxygen species (ROS) production, coupled with downregulation of anti-apoptotic molecules (Bcl-2, Bcl-xL) led to reduction of mitochondrial membrane potential (MMP) and release of cytochrome c in both human breast cancer cells treated with vernodalin. Release of cytochrome c from mitochondria to cytosol triggered activation of caspase cascade, PARP cleavage, DNA damage and eventually cell death.
To the best of our knowledge, this is the first comprehensive study on cytotoxic and apoptotic mechanism of vernodalin isolated from the Centratherum anthelminticum (L.) seeds in human breast cancer cells. Overall, our data suggest a potential therapeutic value of vernodalin to be further developed as new anti-cancer drug.
Supercritical propanol has been used to extract and remove the epoxy resin from the surface of a carbon fibre composite material. The process appeared to be effective when operating above 450
°C and ...above 50
bar. The recovered fibres were found to be virtually as strong, in terms of tensile strength, as the virgin fibres indicating that little had been done to damage their structural integrity. One advantage of this method is that the polymer, as well as the fibre material, can be recovered. The polymer was analysed to investigate what chemical transformations had occurred during treatment. It is seems likely that the amide cross-linker is broken in the polymer to release a residue with a relatively high molecular weight.
In this study, a new apoptotic monoterpenoid indole alkaloid, subditine (1), and four known compounds were isolated from the bark of Nauclea subdita. Complete (1)H- and (13)C- NMR data of the new ...compound were reported. The structures of isolated compounds were elucidated with various spectroscopic methods such as 1D- and 2D- NMR, IR, UV and LCMS. All five compounds were screened for cytotoxic activities on LNCaP and PC-3 human prostate cancer cell-lines. Among the five compounds, the new alkaloid, subditine (1), demonstrated the most potent cell growth inhibition activity and selective against LNCaP with an IC50 of 12.24±0.19 µM and PC-3 with an IC50 of 13.97±0.32 µM, compared to RWPE human normal epithelial cell line (IC50 = 30.48±0.08 µM). Subditine (1) treatment induced apoptosis in LNCaP and PC-3 as evidenced by increased cell permeability, disruption of cytoskeletal structures and increased nuclear fragmentation. In addition, subditine (1) enhanced intracellular reactive oxygen species (ROS) production, as reflected by increased expression of glutathione reductase (GR) to scavenge damaging free radicals in both prostate cancer cell-lines. Excessive ROS could lead to disruption of mitochondrial membrane potential (MMP), release of cytochrome c and subsequent caspase 9, 3/7 activation. Further Western blot analyses showed subditine (1) induced down-regulation of Bcl-2 and Bcl-xl expression, whereas p53 was up-regulated in LNCaP (p53-wild-type), but not in PC-3 (p53-null). Overall, our data demonstrated that the new compound subditine (1) exerts anti-proliferative effect on LNCaP and PC-3 human prostate cancer cells through induction of apoptosis.
The Theory of Planned Behavior (TPB) is a useful framework that helps explain people's behavior across a wide range of settings. The present study adopted the TPB to investigate factors that affect ...the complexity of the learning intention of workers involved with a lean manufacturing training initiative. Even though workers' training has been consistently listed as a critical success factor for innovative improvement initiatives, very few studies explore direct workers' learning intentions. This is particularly true within the area of lean manufacturing training. Hence, direct workers in an automotive parts manufacturing organization were invited to participate in this study, to which 204 workers voluntarily responded. The survey data was compiled and analyzed through stepwise regression to establish the effects of the different factors on learning intention in lean manufacturing training. It was determined from the empirical results that the participants' attitude toward learning from lean manufacturing training and the perceived behavioral control factors positively affected the workers' learning intention. Organization management could look into different measures and policies to stimulate better learning effects from training programs among the participants. Actions that could foster positive attitudes and confidence of workers towards lean training initiatives will be most helpful in enabling effective and innovative lean practices on the organization's shop floors. The key theoretical and managerial implications, as well as the limitations of the study, are also discussed.
Glass fibre reinforced polymer (GFRP) remains the dominant composite produced globally due to its low cost, high specific mechanical properties and chemical resistance performances. These unique ...features, however, impose significant recycling challenges for their end-of-life parts. Although there are various recycling technologies available, all of them require the waste GFRP to be reduced in size in order to enhance the recycling process efficiency. In this work, a full factorial design analysis was conducted to identify factors that influenced specific shredding energy consumption, average physical size and resin content of shredded GFRP recyclates. Factors investigated were glass fibre fabric architecture in GFRP wastes (non-crimp and nonwoven), GFRP waste feed rate (10–60 kg/h) and screen aperture of the shredding process (6–20 mm). It was observed that specific shredding energy was not significantly affected by the fabric architecture but could be reduced by opting for larger screen aperture and/or lower feed rate. However, improvement to shredding energy efficiency was achieved if 6 mm diameter screen was selected together with 60 kg/h feed rate. The 60 kg/h feed rate was found to be ideal in reducing oversize recyclates content but did not affect the median particle size of the remaining recyclates, which was found to be influenced by screen aperture and fabric architecture. Resin-rich and fibre-rich fractions were identified from the recyclates. The resin content of the former was found to be sensitive to all the studied factors.
•Factors affecting comminution of GFRP materials and their recyclates properties were studied.•Specific shredding energy was reduced using a smaller feed rate or larger screen aperture size.•Oversized recyclates were found in all studied samples but could be reduced with larger feed rate.•Recyclate's average size was influenced by glass fibre fabric structure and screen aperture size.•Resin content of resin-rich recyclates was affected by all factors investigated in this study.
Carbon fibre composites with an epoxy resin matrix were subjected to microwave-heating experiments in order to volatilise the polymer content and to produce clean fibres for potential reuse in ...high-grade applications. The composites were processed at 3
kW for 8
s in a multimode microwave applicator. The recovered fibres were characterised by tensile tests and electron microscopy. The results compare favourably with virgin fibre properties.
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•Four economic preconditions ensure re-entry of recovered fiber into circular system.•Rapid heating rate and high temperature reduce char formation on carbon fiber.•Effect of inert ...gas flow on reduction of char residues is only obvious at 550 °C.•Improved pyrolysis conditions increase char intrinsic reactivity and oxidation rate.
Wind energy has been considered as one of the greenest renewable energy sources over the last two decades. However, attention is turning to reducing the possible environmental impacts from this sector. We argue that wind energy would not be effectively “green” if anthropogenic materials are not given attention in a responsible manner. Using the concept of the circular economy, this paper considers how anthropogenic materials in the form of carbon fibers can reenter the circular economy system at the highest possible quality. This paper first investigates the viability of a carbon-fiber-reinforced polymer extraction process using thermal pyrolysis to recalibrate the maximum carbon fiber value by examining the effect of (a) heating rate, (b) temperature, and (c) inert gas flow rate on char yield. With cleaner and higher quality recovered carbon fibers, this paper discusses the economic preconditions for the takeoff and growth of the industry and recommends the reuse of extracted carbon fibers to close the circular economy loop.
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