Journal articles on the topic 'L-PBF based processing route'
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1
Obasa, Victoria Dumebi, Oludolapo Akanni Olanrewaju, Oluwashina Phillips Gbenebor, Ezenwanyi Fidelia Ochulor, Cletus Chiosa Odili, Yetunde Oyebolaji Abiodun, and Samson Oluropo Adeosun. "A Review on Lignin-Based Carbon Fibres for Carbon Footprint Reduction." Atmosphere 13, no. 10 (September 30, 2022): 1605. http://dx.doi.org/10.3390/atmos13101605.
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Carbon fibers (CFs) are made mostly from a non-environmentally friendly polyacrylonitrile (PAN) and little from rayon. PAN-based CFs, require huge amount of energy for its production aside its contributions to the global CO2 emission. Therefore, there is recourse to a more environmentally friendly sources of CFs biomass. Recently lignin has been recognized as a potential renewable raw material for carbon fibers to replace PAN-based. The magnitude and quality of CO2 emission of lignin-based CFs are dependent on the processing route. On this premise; this review examines the various lignin-based CFs processing route adopted by researcher in the recent past to establish the most viable route with minimum carbon footprint emission. Outcome of the review shows that the major advantages of aromatic polymer (AP) generated precursor over PAN is the presence of higher quantity of guaiacyl units and oxygen content which makes the stabilization phase efficient and faster requiring less energy. Though there are several methods and options for the various stages of conversion of lignocellulosic biomass into CFs as highlighted in the study, establishing an optimum processing route will be a trade-off amongst various issues of concern; carcinogenic risk, carbon footprint emission, CFs Yield and mechanical strength of the CFs. Inferences from the study shows that the L-CF significantly produced reduced climatic impact in terms of CO2 emission.
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Naffakh, Mohammed. "Biopolymer Nanocomposite Materials Based on Poly(L-lactic Acid) and Inorganic Fullerene-like WS2 Nanoparticles." Polymers 13, no. 17 (August 31, 2021): 2947. http://dx.doi.org/10.3390/polym13172947.
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In the current study, inorganic fullerene (IF)-like tungsten disulphide (WS2) nanoparticles from layered transition metal dichalcogenides (TMDCs) were introduced into a poly(L-lactic acid) (PLLA) polymer matrix to generate novel bionanocomposite materials through an advantageous melt-processing route. The effectiveness of employing IF-WS2 on the morphology and property enhancement of the resulting hybrid nanocomposites was evaluated. The non-isothermal melt–crystallization and melting measurements revealed that the crystallization and melting temperature as well as the crystallinity of PLLA were controlled by the cooling rate and composition. The crystallization behaviour and kinetics were examined by using the Lui model. Moreover, the nucleating effect of IF-WS2 was investigated in terms of Gutzow and Dobreva approaches. It was discovered that the incorporation of increasing IF-WS2 contents led to a progressive acceleration of the crystallization rate of PLLA. The morphology and kinetic data demonstrate the high performance of these novel nanocomposites for industrial applications.
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Kaushal, Sarbjeet, Dilkaran Singh, Dheeraj Gupta, and Vivek Jain. "Processing of Ni–WC–Cr3C2-based metal matrix composite cladding on SS-316L substrate through microwave irradiation." Journal of Composite Materials 53, no. 8 (August 19, 2018): 1023–32. http://dx.doi.org/10.1177/0021998318794846.
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The present paper reports on the development of metal matrix composite clads of Ni–WC–Cr3C2-based materials through microwave heating route. In this study, metal matrix composite clads were deposited on austenitic stainless steel (SS-316 L) inside a multimode-type domestic microwave oven. Experiment trials were carried out at a microwave power of 900 W and frequency of 2.45 GHz. The optimal exposure time for processing of metal matrix composite clads was varied from 60 to 360 s. The microstructural analysis of processed clads revealed that the metal matrix composite clads of approximately 0.85 mm thickness were free from any type of voids and cracks. The WC and Cr3C2 particles were dispersed inside the Ni matrix. The phase analysis results revealed the formation of Cr7Ni3, NiC, Fe6W6C, Co3W3C4, FeNi3, NiW phases inside the clad layer. The formation of hard carbide phases resulted in higher microhardness of the clad layer. The average value of Vicker’s microhardness was observed to be 503 ± 34 HV, which is almost 1.6 times that of the substrate.
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Varvara, Simona, Sorin-Aurel Dorneanu, Alexandru Okos, Liana Maria Muresan, Roxana Bostan, Maria Popa, Daniel Marconi, and Petru Ilea. "Dissolution of Metals in Different Bromide-Based Systems: Electrochemical Measurements and Spectroscopic Investigations." Materials 13, no. 16 (August 17, 2020): 3630. http://dx.doi.org/10.3390/ma13163630.
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The dissolution of the main metals (Cu, Zn, Sn, Pb and Fe) found in waste printed circuit boards (WPCBs) was investigated by electrochemical corrosion measurements (potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)) in different bromide-based systems that could be used as lixiviants in hydrometallurgical route of metals recovery. The analysis of the corrosion products was carried out by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements. All measurements showed that the addition of bromine in the electrolyte favors to great extents the dissolution process of all studied metals as compared to bromine-free electrolytes. In the investigated experimental conditions, the highest dissolution rates of the metals were obtained in acidic KBr solution containing 0.01 mol/L bromine and they decreased in the following order: Zn >> Sn > Pb > Fe > Cu. The XRD and XPS chemical assessment allowed the identification of the dissolution products formed on the metallic surfaces after exposure to the electrolytes. They consisted mainly of oxides in the case of Cu, Zn, Sn and Fe, while the presence of PbBr2 was also noticed on the lead surface. Based on the results of EIS and surface investigations, several models explaining the corrosion behavior of the metals were proposed and discussed. The obtained results demonstrate that all studied metals could be successfully leached using brominated solutions, providing a viable alternative for the selective and efficient recovery of the base metals from WPCBs through a multi-step hydrometallurgical processing route.
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Naffakh, Mohammed. "Nanocomposite Materials Based on TMDCs WS2 Modified Poly(l-Lactic Acid)/Poly(Vinylidene Fluoride) Polymer Blends." Polymers 13, no. 13 (June 30, 2021): 2179. http://dx.doi.org/10.3390/polym13132179.
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Novel multifunctional biopolymer blend nanocomposites composed of poly(vinylidene fluoride)(PVDF) and tungsten disulfide nanotubes (INT-WS2) that are layered transition metal dichalcogenides (TMDCs) were easily prepared by applying an economical, scalable, and versatile melt processing route. Furthermore, their synergistic effect to enhance the properties of poly(L-lactic acid) (PLLA) matrix was investigated. From morphological analysis, it was shown that the incorporation of 1D (INT)-WS2 into the immiscible PLLA/PVDF mixtures (weight ratios: 80/20, 60/40, 40/60, and 20/80) led to an improvement in the dispersibility of the PVDF phase, a reduction in its average domain size, and consequently a larger interfacial area. In addition, the nanoparticles INT-WS2 can act as effective nucleating agents and reinforcing fillers in PLLA/PVDF blends, and as such, greatly improve their thermal and dynamic-mechanical properties. The improvements are more pronounced in the ternary blend nanocomposites with the lowest PVDF content, likely due to a synergistic effect of both highly crystalline PVDF and 1D-TMDCs nano-additives on the matrix performance. Considering the promising properties of the developed materials, the inexpensive synthetic process, and the extraordinary properties of environmentally friendly and biocompatibe 1D-TMDCs WS2, this work may open up opportunities to produce new PLLA/PVDF hybrid nanocomposites that show great potential for biomedical applications.
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Nagy, Ildikó, and János Tamás. "Optimization of Density of Sugar Beet (Beta vulgaris L.) Production Quotas by Pointwise Geostatistic Methods." Acta Agraria Debreceniensis, no. 18 (March 4, 2005): 46–50. http://dx.doi.org/10.34101/actaagrar/18/3246.
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The regional distribution of the Hungarian sugar beet production quotas was developed by the conventional concurrency relationships. In our research we analyzed 320 sectors of 9 factories with geostatistic methods in a GIS environment. The applied researches of spatial mean, spatial deviation, deviational ellipse have been introduced by us in this speciality. We used two different methods in our optimization inquiries, where the spatial segment of the standard deviational ellipse was based on a more robust preliminary data processing solution, and this is why it is a less parametricable method. The inquiry of the spatial buffer zones in production sectors ensures an obvious optimization possibility. We considered the supply route distances in both cases as a modeling boundary condition. Our results show that we introduced an effective decision making method to the occurent replanning of the production sectors with the pointwise density inquiries and the geometric analogy that was fitted to it.
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Ghosh, S., Júlio C. Viana, Rui L. Reis, and João F. Mano. "Osteochondral Tissue Engineering Constructs with a Cartilage Part Made of Poly(L-lactic Acid) / Starch Blend and a Bioactive Poly(L-Lactic Acid) Composite Layer for Subchondral Bone." Key Engineering Materials 309-311 (May 2006): 1109–12. http://dx.doi.org/10.4028/www.scientific.net/kem.309-311.1109.
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Articular cartilage has an inadequate natural rebuilding capacity. Tissue engineering has shown to have potential to provide an effective alternative to engineer the damaged cartilage. In this study, an integrated porous bi-layered scaffold was developed aiming to mimic the requirements of cartilage and underlying subchondral bone. The osteochondral approach explored in this work was to include a common polymeric component in both cartilage and bone components, which maximised the integration at the interface by mean of a melt-based processing route. A blend of starch and poly(Llactic acid),PLLA, was used in the cartilage side, which was found to possess an adequate water uptake capability. For the bone region, to induce bioactivity, PLLA had been reinforced with hydroxyapatite (HA) and bioactive glass (BG). The surfaces of the constructs were investigated as a function of soaking time in a simulated body (SBF) fluid using scanning electron microscopy (SEM) and FTIR. The SEM – FTIR indicated a bone-like apatite formation and the surface coverage by apatite layer increased with increasing soaking time, whereas the cartilage-layer did not exhibit the formation of any apatite like layer.
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Yongvanich, Niti, Bovornrat Emtip, Boonyarit Hengprayoon, and Ekkapot Jankat. "Synthesis of Spinel Color Pigments from Aluminum Dross Waste." Key Engineering Materials 766 (April 2018): 282–87. http://dx.doi.org/10.4028/www.scientific.net/kem.766.282.
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Spinel-based ceramic color pigments were successfully synthesized from utilization of aluminum dross waste and relevant oxide precursors by solid-state processing. Cobalt ions were selected as a chromophore to produce blue pigments. The conventional oxide route was also carried out for comparison purposes. The spinel phase readily formed when fired at 1100 °C; longer duration yielded a higher degree of purity. No preferential orientation of XRD reflection was observed, indicating random crystallographic arrangement. Phase formation was also confirmed by Fourier Transformed Infrared Spectroscopy (FTIR) which displayed both Co-O tetrahedral and Al-O octahedral which are the main framework for a spinel crystal. Slightly sharper FTIR peaks for the dross route compared to those from the oxide route suggest a difference in crystallinity between the two with different precursors. The particle size distribution was relatively wide (5 – 30 micron), possibly due to a crude nature of the dross precursor. The UV-vis spectra showed absorption in the range of 450-550 nm which is associated with the blue color caused by a shift of the 3d7 electrons of Co2+. The obtained dross-route pigments possessed both a and b color parameters (a = -2.3 to-2.6; b = -3.4 to-4.0) in the negative territory, implying greenness and blueness respectively. The L values were in the 20-30 range. When incorporating into practical glazes, the b parameters unexpectedly became more negative, indicating an even deeper blue tone. This result suggested a high potential for utilization of this dross waste as an alternative precursor source for sustainable production of spinel ceramic pigments.
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Asnafi, Nader. "Application of Laser-Based Powder Bed Fusion for Direct Metal Tooling." Metals 11, no. 3 (March 10, 2021): 458. http://dx.doi.org/10.3390/met11030458.
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The journey of production tools in cold working, hot working, and injection molding from rapid tooling to additive manufacturing (AM) by laser-based powder bed fusion (L-PBF) is described. The current machines and their configurations, tool steel powder materials and their properties, and the L-PBF process parameters for these materials are specified. Examples of production tools designed for and made by L-PBF are described. Efficient design, i.e., high tooling efficiency and performance in operation, should be the primary target in tool design. Topology and lattice structure optimization provide additional benefits. Using efficient design, L-PBF exhibits the greatest potential for tooling in hot working and injection molding. L-PBF yields high tooling costs, but competitive total costs in hot working and injection molding. Larger object sizes that can be made by L-PBF, a larger number of powder metals that are designed for different tooling applications, lower feedstock and L-PBF processing costs, further L-PBF productivity improvement, improved surface roughness through L-PBF, and secured quality are some of the targets for the research and development in the future. A system view, e.g., plants with a high degree of automation and eventually with cyber-physically controlled smart L-PBF inclusive manufacturing systems, is also of great significance.
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Takushima, Shigeru, Nobuhiro Shinohara, Daiji Morita, Hiroyuki Kawano, Yasuhiro Mizutani, and Yasuhiro Takaya. "In-Process Height Displacement Measurement Using Crossed Line Beams for Process Control of Laser Wire Deposition." International Journal of Automation Technology 15, no. 5 (September 5, 2021): 715–27. http://dx.doi.org/10.20965/ijat.2021.p0715.
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We propose the use of the line section method with crossed line beams for the process control of laser wire deposition. This method could be used to measure the height displacement in front of a laser spot when the processing direction changes. In laser processing, especially laser deposition of metal additive manufacturing, the laser process control technique that controls the processing parameters based on the measured height displacement in front of a laser processing spot is indispensable for high-accuracy processing. However, it was impossible to measure the height displacement in front of a processing laser spot in a processing route in which the processing direction changes as the measurement direction of the conventional light-section method comprising the use of a straight-line beam is restricted although the configuration is simple. In this paper, we present an in-process height displacement measurement system of the light-section method using two crossed line beams. This method could be used to measure the height displacement in a ±90° direction by projecting two crossed line beams from the side of a laser processing head with a simple configuration comprising the addition of one line laser to the conventional light-section method. The height displacement can be calculated from the projected position shift of the line beams irrespective of the measurement direction by changing the longitudinal position on the crossed line beams according to the measurement direction. In addition, the configuration of our proposed system is compact because the imaging system is integrated into the processing head. We could measure the height displacement at 2.8–4 mm in front of a laser processing spot according to the measurement direction by reducing the influence of intense thermal radiation. Moreover, we experimentally evaluated the height displacement measurement accuracy for various measurement directions. Finally, we evaluated continuous deposition in an “L” shape wherein the deposition direction was changed while using a laser wire direct energy deposition machine for the laser process control based on the in-process height displacement measurement result. We achieved highly accurate continuous deposition at the position wherein the processing direction changes despite the acceleration and deceleration of the stage by laser process control.
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Fotovvati, Behzad, Madhusudhanan Balasubramanian, and Ebrahim Asadi. "Modeling and Optimization Approaches of Laser-Based Powder-Bed Fusion Process for Ti-6Al-4V Alloy." Coatings 10, no. 11 (November 18, 2020): 1104. http://dx.doi.org/10.3390/coatings10111104.
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Laser-based powder-bed fusion (L-PBF) is a widely used additive manufacturing technology that contains several variables (processing parameters), which makes it challenging to correlate them with the desired properties (responses) when optimizing the responses. In this study, the influence of the five most influential L-PBF processing parameters of Ti-6Al-4V alloy—laser power, scanning speed, hatch spacing, layer thickness, and stripe width—on the relative density, microhardness, and various line and surface roughness parameters for the top, upskin, and downskin surfaces are thoroughly investigated. Two design of experiment (DoE) methods, including Taguchi L25 orthogonal arrays and fractional factorial DoE for the response surface method (RSM), are employed to account for the five L-PBF processing parameters at five levels each. The significance and contribution of the individual processing parameters on each response are analyzed using the Taguchi method. Then, the simultaneous contribution of two processing parameters on various responses is presented using RSM quadratic modeling. A multi-objective RSM model is developed to optimize the L-PBF processing parameters considering all the responses with equal weights. Furthermore, an artificial neural network (ANN) model is designed and trained based on the samples used for the Taguchi method and validated based on the samples used for the RSM. The Taguchi, RSM, and ANN models are used to predict the responses of unseen data. The results show that with the same amount of available experimental data, the proposed ANN model can most accurately predict the response of various properties of L-PBF components.
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Abdullayev, Amanmyrat, Paul H. Kamm, Maged F. Bekheet, and Aleksander Gurlo. "Fabrication and Characterization of Ice Templated Membrane Supports from Portland Cement." Membranes 10, no. 5 (May 9, 2020): 93. http://dx.doi.org/10.3390/membranes10050093.
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Porous ceramic membranes for aqueous microfiltration and ultrafiltration processes suffer from the high-costs of material and processing. The latter is mainly due to the high-temperature sintering step. In this work, cement-based membrane supports from ultrafine Portland cement are studied as a low-cost alternative to traditional oxidic ceramic supports. An environmentally friendly freeze-casting fabrication route is applied for the fabrication of porous membrane supports. Cement membrane supports are becoming mechanically stabile after hydration reaction of cement with water, which does not require any high-temperature sintering step as in a conventional ceramic membrane fabrication process. This fabrication route, which is sintering-free, decreases the cost and environmental impact of the membrane fabrication process by eliminating extra energy consumption step during sintering. The Archimedes method, scanning electron microscopy (SEM), micro-computed tomographic (µCT), and mercury porosimetry characterize the membrane supports in respect to open porosity, pore size distribution, morphology, and connectivity. The flexural strength of the 3 mm thick membranes is in the range from 1 to 6 MPa, as obtained by the ring-on-ring tests. The obtained membrane supports possess porosity in the range between 48 and 73% depending on fabrication conditions (cooling rate and the solid content, as determined by Archimedes method enabling water flux in the range between 79 and 180 L/(h·m2) at 0.5 bar transmembrane pressure difference and 3 mm membrane thickness.
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Caragea, Genica, Andreea C. Vãrzaru, Oana Avram, Radu Macovei, Andreea Costea, Dragos M. Popescu, and Andreea M. Smarandache. "An overview of the complications of acute and chronic mercury exposures. Past, present and future." Romanian Journal of Military Medicine 124, no. 4 (January 11, 2021): 411–19. http://dx.doi.org/10.55453/rjmm.2021.124.4.1.
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Mercury is a chemical element that has been known since prehistoric times and has been used over time as a component of paints, in the treatment of various diseases, and later in various industrial compounds. Mercury enters the body transcutaneously, by inhaling or by ingesting food contaminated with mercury. The most common cause of mercury poisoning is eating seafood, but people can get mercury poisoning from industrial processing, thermometers, dental work, and old paints. The most vulnerable are people at occupational risk due to chronic exposure, as well as fetuses in the intrauterine period. Mercury poisoning produces extremely serious effects on the nervous, renal, and gastrointestinal systems. The nature and extent of mercury poisoning depend on factors such as the route of exposure, the rate of exposure, the distribution and biotransformation of mercury in the body, the chemical form of mercury or the mercury compound. Both mercury in the blood and the urine should not exceed 10 μg/L. The critical values of mercury in the blood are >150 μg/L and the lethal ones exceed 800 μg/L. New diagnostic methods allow the rapid and accurate identification of the concentration of mercury in biological products. Treatment is based on the use of chelating agents. However, the prognosis of mercury poisoning is extremely variable, due to the potentially irreversible nature of the lesions.
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Abdelwahed, Marawan, Riccardo Casati, Sven Bengtsson, Anna Larsson, Martina Riccio, and Maurizio Vedani. "Effects of Powder Atomisation on Microstructural and Mechanical Behaviour of L-PBF Processed Steels." Metals 10, no. 11 (November 5, 2020): 1474. http://dx.doi.org/10.3390/met10111474.
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In this research, steel alloys based on the Fe-Cr-Mo, Fe-Cr-Mn and Fe-Cr-Mo-Mn-Ni systems have been designed, produced by different atomisation techniques, and processed by laser powder bed fusion (L-PBF) to investigate their microstructural and mechanical behaviour. Both gas atomisation and water atomisation were considered for powder preparation. The resulting different flowability of powders, hence a different densification behaviour during processing, could be compensated by tuning the L-PBF parameters and by the application of a post treatment to improve flowability of the water atomised powders. In agreement with thermodynamic calculations, small-size oxide-based nonmetallic inclusions of the type SiO2, MnO-SiO2, Cr2O3-SiO2 were found within the steel matrix and on the fracture surfaces of the water atomised L-PBF alloys, featuring higher amounts of oxygen than the gas-atomised steels. Analyses on microstructure and hardness of the hardenable as-built steels suggested that during laser processing, the multilayer L-PBF structure undergoes an in-situ tempering treatment. Furthermore, the mechanical properties of the L-PBF steels could be widely tuned depending on the post-thermal treatment conditions.
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Polozov, Igor, Anna Gracheva, and Anatoly Popovich. "Processing, Microstructure, and Mechanical Properties of Laser Additive Manufactured Ti2AlNb-Based Alloy with Carbon, Boron, and Yttrium Microalloying." Metals 12, no. 8 (August 3, 2022): 1304. http://dx.doi.org/10.3390/met12081304.
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In this work, Ti-22Al-23Nb-0.8Mo-0.3Si-0.4C-0.1B-0.2Y (at. %) alloy powder was used to fabricate the Ti2AlNb-based alloy samples using Laser powder bed fusion (L-PBF) Additive Manufacturing with a high-temperature substrate preheating. L-PBF process parameters, including laser power, scan speed, hatching distance, and preheating temperature, allowing for obtaining fully dense (99.9% relative density) crack-free samples, were determined. The effects of substrate preheating temperature during the L-PBF process on microstructure, phase composition, and properties of the obtained Ti2AlNb-based alloy were investigated using X-ray diffraction, scanning electron microscopy, electron backscatter diffraction analysis, and microhardness testing. The results obtained for the material with C, B, and Y microalloying were compared to the Ti2AlNb-based alloy fabricated by L-PBF from the powder not alloyed with C, B, and Y. The results revealed that the microalloying reduced the number of solidification cracks; however, no significant microstructural changes were observed, and high-temperature substrate preheating was still necessary to suppress cold cracking of the alloy. The microstructure of the alloy varied from fully-β/B2, B2 + O, to fully-O depending on the preheating temperature. Effects of hot isostatic pressing and heat treatment conditions on microstructure and mechanical properties were investigated.
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Zhang, Shiyun, Jian Xie, Peng Zhang, and Xinbing Zhao. "Low-cost and scalable preparation of nano-Si from photovoltaic waste silicon for high-performance Li-ion battery anode." Functional Materials Letters 14, no. 06 (July 3, 2021): 2151033. http://dx.doi.org/10.1142/s1793604721510334.
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Nano silicon (nano-Si)-based materials have been considered as promising anodes for next-generation Li-ion batteries (LIBs) because of their high specific capacity. However, a facile processing method of nano-Si with cheap Si sources is still lacking. Herein, we propose a facile, scalable and cost-effective route to produce nano-Si using a low-cost Si source from photovoltaic (PV) waste silicon. The nano-Si of 484 nm in [Formula: see text] can be easily produced using the PV waste Si by facile acid washing, heat treatment and sand milling steps. Compared with commercial nano-Si (120 nm), our low-cost nano-Si exhibits higher Coulombic efficiency (87.1%) and better cycling stability. The cycling stability of nano-Si can be obviously enhanced by using a carboxymethyl cellulose (CMC) binder and an electrolyte composed of 1 mol L[Formula: see text] LiPF6 in fluoroethylene carbonate (FEC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) (1:1:1). The nano-Si with CMC binder in 1 mol L[Formula: see text] LiPF6 FEC/EMC/DMC electrolyte could maintain a discharge capacity of 1488 mAh g[Formula: see text] after 200 cycles at 1 A g[Formula: see text]. Our work provides a promising, sustainable method to make high-performance nano-Si using a low-cost Si source.
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Bassoli, Elena, Lucia Denti, Andrea Comin, Antonella Sola, and Emanuele Tognoli. "Fatigue Behavior of As-Built L-PBF A357.0 Parts." Metals 8, no. 8 (August 11, 2018): 634. http://dx.doi.org/10.3390/met8080634.
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Laser-based powder bed fusion (L-PBF) is nowadays the preeminent additive manufacturing (AM) technique to produce metal parts. Nonetheless, relatively few metal powders are currently available for industrial L-PBF, especially if aluminum-based feedstocks are involved. In order to fill the existing gap, A357.0 (also known as A357 or A13570) powders are here processed by L-PBF and, for the first time, the fatigue behavior is investigated in the as-built state to verify the net-shaping potentiality of AM. Both the low-cycle and high-cycle fatigue areas are analyzed to draw the complete Wohler diagram. The infinite lifetime limit is set to 2 × 106 stress cycles and the staircase method is applied to calculate a mean fatigue strength of 60 MPa. This value is slightly lower but still comparable to the published data for AlSi10Mg parts manufactured by L-PBF, even if the A357.0 samples considered here have not received any post-processing treatment.
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Bassoli, Elena, Antonella Sola, Mattia Celesti, Sandro Calcagnile, and Carlo Cavallini. "Development of Laser-Based Powder Bed Fusion Process Parameters and Scanning Strategy for New Metal Alloy Grades: A Holistic Method Formulation." Materials 11, no. 12 (November 22, 2018): 2356. http://dx.doi.org/10.3390/ma11122356.
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In spite of the fast growth of laser-based powder bed fusion (L-PBF) processes as a part of everyday industrial practice, achieving consistent production is hampered by the scarce repeatability of performance that is often encountered across different additive manufacturing (AM) machines. In addition, the development of novel feedstock materials, which is fundamental to the future growth of AM, is limited by the absence of established methodologies for their successful exploitation. This paper proposes a structured procedure with a complete test plan, which defines step-by-step the standardized actions that should be taken to optimize the processing parameters and scanning strategy in L-PBF of new alloy grades. The method is holistic, since it considers all the laser/material interactions in different local geometries of the build, and suggests, for each possible interaction, a specific geometry for test specimens, standard energy parameters to be analyzed through a design of experiment, and measurable key performance indicators. The proposed procedure therefore represents a sound and robust aid to the development of novel alloy grades for L-PBF and to the definition of the most appropriate processing conditions for them, independent of the specific AM machine applied.
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Jain, Srishti, James Hyder, Mike Corliss, and Wayne NP Hung. "Electrochemical Polishing of Extruded and Laser Powder-Bed-Fused Inconel 718." International Journal of Engineering Materials and Manufacture 6, no. 4 (October 1, 2021): 284–98. http://dx.doi.org/10.26776/ijemm.06.04.2021.04.
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ABSTRACT Electro-chemical polishing (ECP) was utilized to produce sub-micron surface finish on Inconel 718 parts manufactured by Laser Powder-Bed-Fusion (L-PBF) and extrusion methods. The L-PBF parts had very rough surfaces due to semi-welded powder particles, surface defects, and difference layer steps that were generally not found on surfaces of extruded and machined components. This study compared the results of electro-polishing of these differently manufactured parts under the same conditions. Titanium electrode was used with an acid-based electrolyte to polish both the specimens at different combinations of pulsed current density, duty cycle, and polishing time. Digital 3D optical profiler was used to assess the surface finish, while optical and scanning electron microscopy was utilized to observe the microstructure of polished specimens. At optimal condition, the ECP successfully reduced the surface of L-PBF part from 17 µm to 0.25 µm; further polishing did not improve the surface finish due to different removal rates of micro-leveled pores, cracks, nonconductive phases, and carbide particles in 3D-printed Inconel 718. The microstructure of extruded materials was uniform and free of processing defects, therefore can be polished consistently to 0.20 µm. Over-polishing of extruded material could improve its surface finish, but not for the L-PBF material due to defects and the surrounding micro-strain.
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Artzt, Katia, Martin Siggel, Jan Kleinert, Joerg Riccius, Guillermo Requena, and Jan Haubrich. "Pyrometric-Based Melt Pool Monitoring Study of CuCr1Zr Processed Using L-PBF." Materials 13, no. 20 (October 16, 2020): 4626. http://dx.doi.org/10.3390/ma13204626.
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The potential of in situ melt pool monitoring (MPM) for parameter development and furthering the process understanding in Laser Powder Bed Fusion (LPBF) of CuCr1Zr was investigated. Commercial MPM systems are currently being developed as a quality monitoring tool with the aim of detecting faulty parts already in the build process and, thus, reducing costs in LPBF. A detailed analysis of coupon specimens allowed two processing windows to be established for a suitably dense material at layer thicknesses of 30 µm and 50 µm, which were subsequently evaluated with two complex thermomechanical-fatigue (TMF) panels. Variations due to the location on the build platform were taken into account for the parameter development. Importantly, integrally averaged MPM intensities showed no direct correlation with total porosities, while the robustness of the melting process, impacted strongly by balling, affected the scattering of the MPM response and can thus be assessed. However, the MPM results, similar to material properties such as porosity, cannot be directly transferred from coupon specimens to components due to the influence of the local part geometry and heat transport on the build platform. Different MPM intensity ranges are obtained on cuboids and TMF panels despite similar LPBF parameters. Nonetheless, besides identifying LPBF parameter windows with a stable process, MPM allowed the successful detection of individual defects on the surface and in the bulk of the large demonstrators and appears to be a suitable tool for quality monitoring during fabrication and non-destructive evaluation of the LPBF process.
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Harkin, Ryan, Hao Wu, Sagar Nikam, Shuo Yin, Rocco Lupoi, Wilson McKay, Patrick Walls, Justin Quinn, and Shaun McFadden. "Powder Reuse in Laser-Based Powder Bed Fusion of Ti6Al4V—Changes in Mechanical Properties during a Powder Top-Up Regime." Materials 15, no. 6 (March 17, 2022): 2238. http://dx.doi.org/10.3390/ma15062238.
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The properties of Extra Low Interstitials (ELI) Ti6Al4V components fabricated via the laser-based powder bed fusion (L-PBF) process are prone to variation, particularly throughout a powder reuse regime. Interstitial pick-up of interstitial elements within the build chamber during processing can occur, most notably, oxygen, nitrogen, and hydrogen, which can impair the mechanical properties of the built component. This study analyses ELI Ti6Al4V components manufactured by the L-PBF process when subjected to a nine-stage powder reuse sequence. Mechanical properties are reported via hardness measurement and tensile testing. Results showed that from 0.099 wt.% to 0.126 wt.% oxygen content, the mean hardness and tensile strength increased from 367.8 HV to 381.9 HV and from 947.6 Mpa to 1030.7 Mpa, respectively, whereas the ductility (area reduction) reduced from around 10% to 3%. Statistical analysis based on the empirical model from Tabor was performed to determine the strength–hardness relationship. Results revealed a significant direct relationship between tensile strength and Vickers hardness with a proportionality constant of 2.61 (R-square of 0.996 and p-value of 6.57 × 10−6).
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Goll, Dagmar, Felix Trauter, Ralf Loeffler, Thomas Gross, and Gerhard Schneider. "Additive Manufacturing of Textured FePrCuB Permanent Magnets." Micromachines 12, no. 9 (August 31, 2021): 1056. http://dx.doi.org/10.3390/mi12091056.
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Permanent magnets based on FePrCuB were realized on a laboratory scale through additive manufacturing (laser powder bed fusion, L-PBF) and book mold casting (reference). A well-adjusted two-stage heat treatment of the as-cast/as-printed FePrCuB alloys produces hard magnetic properties without the need for subsequent powder metallurgical processing. This resulted in a coercivity of 0.67 T, remanence of 0.67 T and maximum energy density of 69.8 kJ/m3 for the printed parts. While the annealed book-mold-cast FePrCuB alloys are easy-plane permanent magnets (BMC magnet), the printed magnets are characterized by a distinct, predominantly directional microstructure that originated from the AM process and was further refined during heat treatment. Due to the higher degree of texturing, the L-PBF magnet has a 26% higher remanence compared to the identically annealed BMC magnet of the same composition.
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Macioł, Piotr, Jan Falkus, Paulina Indyka, and Beata Dubiel. "Towards Automatic Detection of Precipitates in Inconel 625 Superalloy Additively Manufactured by the L-PBF Method." Materials 14, no. 16 (August 11, 2021): 4507. http://dx.doi.org/10.3390/ma14164507.
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In our study, the comparison of the automatically detected precipitates in L-PBF Inconel 625, with experimentally detected phases and with the results of the thermodynamic modeling was used to test their compliance. The combination of the complementary electron microscopy techniques with the microanalysis of chemical composition allowed us to examine the structure and chemical composition of related features. The possibility of automatic detection and identification of precipitated phases based on the STEM-EDS data was presented and discussed. The automatic segmentation of images and identifying of distinguishing regions are based on the processing of STEM-EDS data as multispectral images. Image processing methods and statistical tools are applied to maximize an information gain from data with low signal-to-noise ratio, keeping human interactions on a minimal level. The proposed algorithm allowed for automatic detection of precipitates and identification of interesting regions in the Inconel 625, while significantly reducing the processing time with acceptable quality of results.
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Kusoglu, Ihsan Murat, Carlos Doñate-Buendía, Stephan Barcikowski, and Bilal Gökce. "Laser Powder Bed Fusion of Polymers: Quantitative Research Direction Indices." Materials 14, no. 5 (March 2, 2021): 1169. http://dx.doi.org/10.3390/ma14051169.
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Research on Laser Powder Bed Fusion (L-PBF) of polymer powder feedstocks has raised over the last decade due to the increased utilization of the fabricated parts in aerospace, automotive, electronics, and healthcare applications. A total of 600 Science Citation Indexed articles were published on the topic of L-PBF of polymer powder feedstocks in the last decade, being cited more than 10,000 times leading to an h-index of 46. This study statistically evaluates the 100 most cited articles to extract reported material, process, and as-built part properties to analyze the research trends. PA12, PEEK, and TPU are the most employed polymer powder feedstocks, while size, flowability, and thermal behavior are the standardly reported material properties. Likewise, process properties such as laser power, scanning speed, hatch spacing, powder layer thickness, volumetric energy density, and areal energy density are extracted and evaluated. In addition, material and process properties of the as-built parts such as tensile test, flexural test, and volumetric porosity contents are analyzed. The incorporation of additives is found to be an effective route to enhance mechanical and functional properties. Carbon-based additives are typically employed in applications where mechanical properties are essential. Carbon fibers, Ca-phosphates, and SiO2 are the most reported additives in the evaluated SCI-expanded articles for L-PBF of polymer powder feedstocks. A comprehensive data matrix is extracted from the evaluated SCI-index publications, and a principal component analysis (PCA) is performed to explore correlations between reported material, process, and as-built parts.
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Denti, Lucia, and Antonella Sola. "On the Effectiveness of Different Surface Finishing Techniques on A357.0 Parts Produced by Laser-Based Powder Bed Fusion: Surface Roughness and Fatigue Strength." Metals 9, no. 12 (November 29, 2019): 1284. http://dx.doi.org/10.3390/met9121284.
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Laser-based powder bed fusion (L-PBF) is an additive manufacturing (AM) technique that uses a computer-controlled laser beam as the energy source to consolidate a metal powder according to a layer-upon-layer strategy in order to manufacture a three dimensional part. This opens the way for an unprecedented freedom in geometry, but the layer-wise build-up strategy typically results in a very poor surface finish, which is affected by the staircase effect and by the presence of partially molten particles. Surface finishing treatments are therefore necessary to obtain an adequate surface finish, to improve the fatigue behavior and to meet mechanical and aesthetic needs. The present contribution systematically compares numerous surface finishing techniques, including laser shock processing, plastic media blasting, sand blasting, ceramic shot peening and metal shot peening with steel particles of different sizes (ϕ = 0.2 mm and ϕ = 0.4 mm). The results show that all the proposed methods improve the surface quality and the fatigue life of A357.0 L-PBF parts. However, the achievement of the lowest surface roughness does not necessarily correspond to the best fatigue performance, thus suggesting that multiple mechanisms may be active and that besides surface roughness also residual stresses contribute to increase the fatigue strength.
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Cacace, Stefania, and Quirico Semeraro. "Fast optimisation procedure for the selection of L-PBF parameters based on utility function." Virtual and Physical Prototyping 17, no. 2 (November 16, 2021): 125–37. http://dx.doi.org/10.1080/17452759.2021.1998871.
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Konda, Nithin, Raviraj Verma, and Rengaswamy Jayaganthan. "Machine Learning Based Predictions of Fatigue Crack Growth Rate of Additively Manufactured Ti6Al4V." Metals 12, no. 1 (December 27, 2021): 50. http://dx.doi.org/10.3390/met12010050.
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The present work focusses on machine learning assisted predictions of the fatigue crack growth rate (FCGR) of Ti6Al4V (Ti64) processed through laser powder bed fusion (L-PBF) and post processing. Various machine learning techniques have provided a flexible approach for explaining the complex mathematical interrelationship among processing-structure-property of the materials. In the present work, four machine learning (ML) algorithms, such as K- Nearest Neighbor (KNN), Decision Trees (DT), Random Forests (RF), and Extreme Gradient Boosting (XGB) algorithms are implemented to analyze the Fatigue Crack growth rate (FCGR) of Ti64 alloy. After tuning the hyper parameters for these algorithms, the trained models were found to estimate the unseen data as equally well as the trained data. The four tested ML models are compared with each other over the training as well as testing phase, based on their mean squared error and R2 scores. Extreme Gradient Boosting has performed better for the FCGR predictions providing least mean squared errors and higher R2 scores compared to other models.
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Wang, Yinmin (Morris), Chandrika Kamath, Thomas Voisin, and Zan Li. "A processing diagram for high-density Ti-6Al-4V by selective laser melting." Rapid Prototyping Journal 24, no. 9 (November 12, 2018): 1469–78. http://dx.doi.org/10.1108/rpj-11-2017-0228.
Full textAbstract:
Purpose Density optimization is the first critical step in building additively manufactured parts with high-quality and good mechanical properties. The authors developed an approach that combines simulations and experiments to identify processing parameters for high-density Ti-6Al-4V using the laser powder-bed-fusion technique. A processing diagram based on the normalized energy density concept is constructed, illustrating an optimized processing window for high- or low-density samples. Excellent mechanical properties are obtained for Ti-6Al-4V samples built from the optimized window. Design/methodology/approach The authors use simple, but approximate, simulations and selective experiments to design parameters for a limited set of single track experiments. The resulting melt-pool characteristics are then used to identify processing parameters for high-density pillars. A processing diagram is built and excellent mechanical properties are achieved in samples built from this window. Findings The authors find that the laser linear input energy has a much stronger effect on the melt-pool depth than the melt-pool width. A processing diagram based on normalized energy density and normalized hatch spacing was constructed, qualitatively indicating that high-density samples are produced in a region when 1 < E* < 2. The onset of void formation and low-density samples occur as E* moves beyond a value of 2. The as-built SLM Ti-6Al-4V shows excellent mechanical performance. Originality/value A combined approach of computer simulations and selected experiments is applied to optimize the density of Ti-6Al-4V, via laser powder-bed-fusion (L-PBF) technique. A series of high-density samples are achieved. Some special issues are identified for L-PBF processes of Ti-6Al-4V, including the powder particle sticking and part swelling issues. A processing diagram is constructed for Ti-6Al-4V, based on the normalized energy density and normalized hatch spacing concept. The diagram illustrates windows with high- and low-density samples. Good mechanical properties are achieved during tensile tests of near fully dense Ti-6Al-4V samples. These good properties are attributed to the success of density optimization processes.
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Phutela, Chinmay, Federico Bosio, Alya Alhammadi, Nujood Alshehhi, Lewis Kindleyside, and Nesma T. Aboulkhair. "Incorporating the Roles of Feature Size and Build Orientation in the Process-Structure-Property Relationship for Additively Manufactured Parts." Metals 13, no. 1 (January 11, 2023): 151. http://dx.doi.org/10.3390/met13010151.
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Laser powder bed fusion (L-PBF) additive manufacturing has reached wide-scale technology readiness for various sectors. However, some challenges posed by the complex nature of the process persist. Limited studies investigated the correlation between the micro- and macroscopic properties of L-PBF AlSi10Mg parts and the features’ sizes with the build orientation in mind. Therefore, this study presents a comprehensive view on the “size effect” for samples larger than those available in the literature (up to 12 mm) on the defects, microstructure evolution, and mechanical properties in two build orientations using a fixed set of process parameters. Microstructural differences were observed between the build orientations, but no considerable difference with size change was detected. The porosity content was inversely proportional to the feature size irrespective of the build orientation, leading to an increase in ductility that was more evident in the horizontal specimens (~44%). This was attributed to an in-situ heat treatment. Although specimens oriented parallel to the build direction showed no significant size-effect in terms of the mechanical properties (hardness and tensile), anisotropy was evident. Based on the findings presented in the study and the scientific explanations discussed corroborated by thermal imaging during processing, it is concluded that although any set of ‘optimised’ process parameters will only be valid for a specific size range, the severity of the size-effect changes dynamically based on the range.
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Harkin, Ryan, Hao Wu, Sagar Nikam, Justin Quinn, and Shaun McFadden. "Analysis of Spatter Removal by Sieving during a Powder-Bed Fusion Manufacturing Campaign in Grade 23 Titanium Alloy." Metals 11, no. 3 (March 1, 2021): 399. http://dx.doi.org/10.3390/met11030399.
Full textAbstract:
The Laser-based Powder Bed Fusion (L-PBF) process uses a laser beam to selectively melt powder particles deposited in a layer-wise fashion to manufacture components derived from Computer-Aided Design (CAD) information. During laser processing, material is ejected from the melt pool and is known as spatter. Spatter particles can have undesirable geometries for the L-PBF process, thereby compromising the quality of the powder for further reuse. An integral step in any powder replenishing and reuse procedure is the sieving process. The sieving process captures spatter particles within the exposed powder that have a diameter larger than a defined mesh size. This manuscript reports on Ti6Al4V (Grade 23) alloy powder that had been subjected to seven reuse iterations, focusing on the characterisation of powder particles that had been captured (i.e., removed) by the sieving processes. Characterisation included chemical composition focusing upon interstitial elements O, N and H (wt.%), particle morphology and particle size analysis. On review of the compositional analysis, the oxygen contents were 0.43 wt.% and 0.40 wt.% within the 63 µm and 50 µm sieve-captured powder, respectively. Additionally, it was found that a minimum of 79% and 63% of spatter particles were present within the captured powder removed by the 63 µm and 50 µm sieves, respectively.
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Martelli, Pietro Antonio, Antonio Sivo, Flaviana Calignano, Emilio Bassini, Sara Biamino, and Daniele Ugues. "Parameters Optimization and Repeatability Study on Low-Weldable Nickel-Based Superalloy René 80 Processed via Laser Powder–Bed Fusion (L-PBF)." Metals 13, no. 2 (January 20, 2023): 210. http://dx.doi.org/10.3390/met13020210.
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This work aims to investigate the processability of René 80 via laser powder–bed fusion (L-PBF). René 80 is a poorly weldable Ni-superalloy, currently processed via investment casting to fabricate turbine blades working at an operating temperature of about 850 °C. The L-PBF parameters optimization aims to increase part integrity and enhance processing repeatability. This part was tackled by creating a complete design of experiments (DOE) in which laser power, scan speed and hatching distance were varied accordingly. Optimizing the abovementioned parameters minimized the crack density and pore area fraction. Hence, five parameter sets leading to a crack density lower than 100 µm/mm2 and a pore fraction between 0.045% and 0.085% were selected. Furthermore, the intra-print repeatability was studied by producing three specimens’ repetitions for each optimal set of parameters in the same build. The porosity value obtained was constant among repetitions, and the crack density (around 75 µm/mm2) had a slight standard deviation. The third step of the research assessed the inter-prints repeatability by producing a replica of the five selected parameter sets in a different build and by comparing the results with those studied previously. According to this latter study, the porosity fraction (ca. 0.06%) was constant in intra- and inter-print conditions. Conversely, crack density was lower than 100 µm/mm2 only in three sets of parameters, regardless of the intra- or inter-build cross-check. Finally, the best parameter set was chosen, emphasizing the average flaw fraction (least possible value) and repeatability. Once the optimal densification of the samples was achieved, the alloy’s microstructural features were also investigated.
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Amraoui, Mounira, Chouaib Daoudi, and Mohamed Remram. "Preparation and Characterization of Silver Nanospheroids: Theoretical and Experimental Approaches." Photonics Letters of Poland 9, no. 2 (July 1, 2017): 63. http://dx.doi.org/10.4302/plp.v9i2.683.
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We synthesized silver nanoparticles of different sizes and forms as function of the molar masses of AgNO3, in two different solvent mediums (ethanol, methanol). We carried out the synthesis according to standard chemical route with major modifications. The spectroscopic characterization showed the presence of two distinct absorption bands; the first band at 300 nm and the second shifted to 440 nm. We found a multipolar phenomenon depending on the temperature. The shape and size predicted by the numerical model are conform to the experimental results. The study demonstrated that the nanoparticles have a spheroidal shape. Full Text: PDF ReferencesCecilia Noguez, "Surface Plasmons on Metal Nanoparticles: The Influence of Shape and Physical Environment", J. Phys. Chem. C 111(10), 3806 (2007). CrossRef M. Amraoui , C. Daoudi and M. Remram, Int.Sc.Sci and Tech. Conf. 2015 Ayd?n,Turkey , 11-13 May , 2015 (ISSTC 2015).M. I Gonzalez-Sanchez et al, "Silver nanoparticle based antibacterial methacrylate hydrogels potential for bone graft applications", Mater. Sci. Eng C. Mater. Biol. Appl 50, 332 (2015). CrossRef Xinyi Dong et al, "Shape Control of Silver Nanoparticles by Stepwise Citrate Reduction", J. Phys. Chem. C 113(16), 6573 (2009). CrossRef A. Wolak, M. Grabiec, O. Véron, J. ?P. Blondeau and K. Dzierżęga, "Nanosecond infrared laser-induced precipitation of silver nanoparticles in glass", Phot. Lett. Poland 5(2), 54 (2013). CrossRef A. Zielinska, E. Skwarek, A. Zaleska, M. Gazda and J. Hupka, "Preparation of silver nanoparticles with controlled particle size", Procedia Chemistry 1, 1560 (2009). CrossRef K-S.Chou, Y.Chang and L. Hua, "Studies on the Continuous Precipitation of Silver Nanoparticles", Ind.Eng.Chem.Res 51(13) 4905 (2012). CrossRef A. M. Atta, H. A. Al-Lohedan, A. O. Ezzat, "Synthesis of Silver Nanoparticles by Green Method Stabilized to Synthetic Human Stomach Fluid", Molecules 19(5) 6737 (2014). CrossRef Botasini, S, Méndez, E. "Silver nanoparticle aggregation not triggered by an ionic strength mechanism", J Nanopart Res 15, 1526 (2013). CrossRef V. Amendola, O.M. Bakr, F. Stellacci, "A Study of the Surface Plasmon Resonance of Silver Nanoparticles by the Discrete Dipole Approximation Method: Effect of Shape, Size, Structure, and Assembly", Plasmonics 5(1) 85 (2010). CrossRef L. Jeong, W. Ho Park "Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles", Int. J. Mol. Sci 15, 6857 (2014). CrossRef Peter Monk, Finite element method for Maxwell's equations, (Oxford, Clarendon Press 2003). DirectLinkM.D. Abramoff, P.J. Magalhaes, S.J. Ram, "Image processing with ImageJ", Biophotonics International 11(7), 36 (2004). DirectLink Edward D.Palik, Handbook of optical constants of solids (California, Academic Press Inc, 1985). DirectLink
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Qian, Bo, Hongri Fan, Gang Liu, Jianrui Zhang, and Pei Li. "Self-Supporting Microchannel Liquid-Cooled Plate for T/R Modules Based on Additive Manufacturing: Study on Its Pass Design, Formation Process and Boiling Heat Transfer Performance." Metals 11, no. 11 (October 29, 2021): 1731. http://dx.doi.org/10.3390/met11111731.
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The additive manufacturing technology of laser-based powder bed fusion (L-PBF), which is used to produce boiling heat transfer structures, offers a high processing flexibility and can provide lattice structures with a high surface-to-volume ratio. As an important part of the phased array radar, the plentiful transmit/receive (T/R) modules can generate considerable heat. Targeting this local overheating problem, this study discusses the pass design, the optimal formation process, and boiling heat transfer performance of microchannel liquid-cooled plates based on L-PBF additive manufacturing technology. The optimum design and process parameters were obtained by performing basic channel experiments. On this basis, the design and formation experiments of the microchannel structure were performed, and then the porosity and pore morphology of microchannel liquid-cooled plate samples were analysed. The boiling heat transfer experiments were conducted with deionised water, and the boiling heat transfer characteristics were compared with the saturated boiling curve of a traditional copper-tube liquid-cooled plate. The average wall temperature of the designed samples decreased by 4% compared with that of the traditional liquid-cooled plate under the same heat flow density the value reduced from 111.9 °C to 108.2 °C. Furthermore, within the same optimal boiling temperature range, the average heat flow densities of all the prepared samples increased by >60% compared with those of the traditional liquid-cooled plate the value increased from minimum 16 W∙cm−2 to maximum 34 W∙cm−2. The self-supporting microchannel structure can considerably improve the heat dissipation effect of T/R modules and solve the local overheating problem.
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Kamboj, Nikhil, Antonia Ressler, and Irina Hussainova. "Bioactive Ceramic Scaffolds for Bone Tissue Engineering by Powder Bed Selective Laser Processing: A Review." Materials 14, no. 18 (September 16, 2021): 5338. http://dx.doi.org/10.3390/ma14185338.
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The implementation of a powder bed selective laser processing (PBSLP) technique for bioactive ceramics, including selective laser sintering and melting (SLM/SLS), a laser powder bed fusion (L-PBF) approach is far more challenging when compared to its metallic and polymeric counterparts for the fabrication of biomedical materials. Direct PBSLP can offer binder-free fabrication of bioactive scaffolds without involving postprocessing techniques. This review explicitly focuses on the PBSLP technique for bioactive ceramics and encompasses a detailed overview of the PBSLP process and the general requirements and properties of the bioactive scaffolds for bone tissue growth. The bioactive ceramics enclosing calcium phosphate (CaP) and calcium silicates (CS) and their respective composite scaffolds processed through PBSLP are also extensively discussed. This review paper also categorizes the bone regeneration strategies of the bioactive scaffolds processed through PBSLP with the various modes of functionalization through the incorporation of drugs, stem cells, and growth factors to ameliorate critical-sized bone defects based on the fracture site length for personalized medicine.
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Семенютина, А. В., М. В. Цой, and Н. А. Бугреев. "Evaluation of woody plants of Juniperus L. for urban greening in sparsely wooded regions." World Ecology Journal, no. 1() (March 15, 2020): 97–120. http://dx.doi.org/10.25726/worldjournals.pro/wej.2020.1.5.
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Мониторинговые исследования за растительными объектами позволяют получить массив данных по особенностям роста, фенологии, развитию генеративных органов, характеру плодоношения, качеству семян, устойчивости к стресс-факторам, т.е. по показателям, которые находятся в функциональной зависимости между собой и позволяют судить о степени экологической пластичности растений. Для обоснования перспективности видов рода Juniperus, дальнейшего прогнозирования уровня адаптивности видов за пределами естественного ареала необходима достоверная и актуальная информация об успешности адаптации интродуцентов в условиях урбанизированных территорий малолесных регионов. Цель исследований – обоснование перспективности использования видов рода Juniperus на основе изучения их биологического потенциала в условиях интродукции. Объектами исследований являлись виды рода Juniperus: J. virginiana L., J. sabina L., J. communis L. и их формы, интродуцированные в дендрологических коллекциях Волгоградской области: ФНЦ агроэкологии РАН, кадастр №34:34:000000:122, 34:34:060061:10 и Нижневолжской станции по селекции древесных пород, № 34:36:0000:14:0178. Обследование проводилось маршрутным методом. Изучение сезонных ритмов развития интродуцентов проводилось методом фенологических наблюдений. Характеристика декоративности, роста и развития трех видов Juniperus L. (J. sabina L., J. virginiana L., J. communis L.) в условиях каштановых почв Волгоградской области, оценка репродуктивной способности, особенности размножения различных видов в культуре выявлялись по методикам ФНЦ агроэкологии РАН. Для определения характера плодоношения объектов исследования использовался метод определения массы 1000 семян, взвешивание проводили на весах марки «MASSA-K». Для математической обработки данных использовали стандартные алгоритмы: средняя арифметическая с абсолютной и относительной ошибками; коэффициент вариации для оценки особенностей репродуктивных процессов; достоверность различий между отдельными показателями. Приведена характеристика декоративности, роста и развития трех видов Juniperus L. (J. sabina L., J. virginiana L., J. communis L.) в условиях каштановых почв Волгоградской области. Дана оценка репродуктивной способности, выявлены особенности размножения различных видов в культуре. По комплексу изученных количественных показателей семенного материала установлено, что семена можжевельника виргинского (Juniperus virginiana L.) (10 г) меньше по массе семян обыкновенного практически в полтора раза; масса семян можжевельника казацкого (Juniperus sabina L.) (24 г) больше по массе семян можжевельника обыкновенного в полтора раза и почти в два с половиной раза больше можжевельника виргинского в сравнении с нормативными данными по можжевельнику обыкновенному (масса 1000 шт. которых составила 16 г). Изучение характера плодоношения можжевельника виргинского (J. virginiana) показало, что в 10,0 граммах шишкоягод содержится в среднем 156 ягод и 270 шт семян, выход чистых семян – 15,84 % от массы плодов. В 10,0 граммах шишкоягод можжевельника казацкого (J. sabina) содержится в среднем 86 ягод и 170 шт семян, выход чистых семян – 20,09 % от массы плодов. Установлено, что для озеленения урбанизированных территорий Волгоградской области Juniperus virginiana рекомендуется использовать в аллейных насаждениях, в чистых группах и в качестве второго яруса в насаждениях Betula, Robinia, Pseudotsuga, Larix. Juniperus sabina наиболее ценен для декорирования и укрепления склонов. В садах и парках общего пользования его применение ограничивается, а при озеленении детских учреждений исключается (хвоя и плоды ядовиты). В Волгоградской области Juniperus communis и его формы могут быть использованы на бедных песчаных почвах в групповых посадках, на опушках и в формованных живых изгородях. Пирамидальные формы пригодны на партерах, карликовые – для оформления каменистых участков. Форма с золотистой окраской в небольших группах на газоне. Monitoring studies of plant objects provide an array of data on the characteristics of growth, phenology, the development of generative organs, the specifics of fruiting, seed quality, and resistance to stress factors, i.e. indicators that are in a functional relationship with each other and allow estimating the degree of environmental plasticity of plants. To justify the prospects of species of the Juniperus genus, forecast the adaptability level of species outside the natural range, reliable and relevant information on the success of adaptation of introduced plants in urbanized areas of sparsely wooded regions is necessary. The purpose of the research is to justify the prospects of using species of the Juniperus genus based on the study of their biological potential under the conditions of introduction. The objects of research were species of the Juniperus genus: J. virginiana L., J. sabina L., J. communis L. and their forms introduced in dendrological collections of the Volgograd Region: Federal Research Center of Agroecology of the Russian Academy of Sciences, Cadastre No. 34:34:000000:122, 34:34:060061:10 and the Lower Volga tree breeding station, No. 34:36 0000:14:0178. The survey was conducted by the route method. The seasonal development rhythms of introduced plants were studied by the method of phenological observations. The characteristics of decorativeness, growth, and development of three species of Juniperus L. (J. sabina L., J. virginiana L., J. communis L.) in chestnut soils of the Volgograd Region, the assessment of reproductive ability, and the reproduction specifics of various cultivated species culture were revealed according to the methods of the Federal Scientific Center of Agroecology of the Russian Academy of Sciences. To determine the fruiting specifics of the study objects, the method of determining the mass of 1000 seeds was used; weighing was performed using a MASSA-K brand balance. For mathematical data processing, standard algorithms were used: the arithmetic mean with absolute and relative errors; the coefficient of variation to assess the characteristics of reproductive processes; the significance of differences between individual indicators. The characteristics of decorativeness, growth, and development of three species of Juniperus L. (J. sabina L., J. virginiana L., J. communis L.) in chestnut soils of the Volgograd Region are described. An assessment of reproductive ability is given, the features of reproduction of various cultivate species are revealed. According to the complex of the studied quantitative indicators of the seed material, it was found that the weight of seeds of Virginian juniper (Juniperus virginiana L.) (10 g) was almost half of the weight of common juniper seeds; the weight of the seeds of savin juniper (Juniperus sabina L.) (24 g) exceeded the weight of the seeds of common juniper by 1.5 times and that of Virginian juniper – by 2.5 times, in comparison with the standard data for common juniper (weight of 1000 pcs. – 16 g). A study of the fruiting specifics of Virginian juniper (J. virginiana) showed that 10.0 grams of conifer berries contained an average of 156 berries and 270 seeds, the yield of pure seeds was 15.84% of the fruit weight; 10.0 grams of cone berry of savin juniper (J. sabina) contained an average of 86 berries and 170 seeds, the yield of pure seeds was 20.09% of the fruit weight. It has been established that for landscaping the urban areas of the Volgograd Region, Juniperus virginiana is recommended to be used in alley stands, in clean groups, and as a second tier in the stands of Betula, Robinia, Pseudotsuga, Larix. Juniperus sabina is most valuable for decorating and strengthening slopes. In gardens and public parks, its use is limited, and when planting children's institutions, it is excluded (needles and fruits are poisonous). In the Volgograd Region, Juniperus communis and its forms can be used on poor sandy soils in group plantings, at the edges, and in molded hedges. Pyramidal forms are suitable in the level spaces, dwarf forms – for the design of rocky areas. The form with a golden color can be used in small groups on lawns.
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Fonnesbech Vogel, Birte, Hans Henrik Huss, Bente Ojeniyi, Peter Ahrens, and Lone Gram. "Elucidation of Listeria monocytogenesContamination Routes in Cold-Smoked Salmon Processing Plants Detected by DNA-Based Typing Methods." Applied and Environmental Microbiology 67, no. 6 (June 1, 2001): 2586–95. http://dx.doi.org/10.1128/aem.67.6.2586-2595.2001.
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ABSTRACT The contamination routes of Listeria monocytogenes in cold-smoked salmon processing plants were investigated by analyzing 3,585 samples from products (produced in 1995, 1996, 1998, and 1999) and processing environments (samples obtained in 1998 and 1999) of two Danish smokehouses. The level of product contamination in plant I varied from 31 to 85%, and no L. monocytogenes was found on raw fish (30 fish were sampled). In plant II, the levels of both raw fish and product contamination varied from 0 to 25% (16 of 185 raw fish samples and 59 of 1,000 product samples were positive for L. monocytogenes). A total of 429 strains of L. monocytogenes were subsequently compared by random amplified polymorphic DNA (RAPD) profiling, and 55 different RAPD types were found. The RAPD types detected on the products were identical to types found on the processing equipment and in the processing environment, suggesting that contamination of the final product (cold-smoked salmon) in both plants (but primarily in plant I) was due to contamination during processing rather than to contamination from raw fish. However, the possibility that raw fish was an important source of contamination of the processing equipment and environment could not be excluded. Contamination of the product occurred in specific areas (the brining and slicing areas). In plant I, the same RAPD type (RAPD type 12) was found over a 4-year period, indicating that an established in-house flora persisted and was not eliminated by routine hygienic procedures. In plant II, where the prevalence of L. monocytogenes was much lower, no RAPD type persisted over long periods of time, and several differentL. monocytogenes RAPD types were isolated. This indicates that persistent strains may be avoided by rigorous cleaning and sanitation; however, due to the ubiquitous nature of the organism, sporadic contamination occurred. A subset of strains was also typed by using pulsed-field gel electrophoresis and amplified fragment length polymorphism profiling, and these methods confirmed the type division obtained by RAPD profiling.
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Timalsina, Bipin, Nawaraj Paudel, and Tej Bahadur Shahi. "Attention based Recurrent Neural Network for Nepali Text Summarization." Journal of Institute of Science and Technology 27, no. 1 (June 30, 2022): 141–48. http://dx.doi.org/10.3126/jist.v27i1.46709.
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Automatic text summarization has been a challenging topic in natural language processing (NLP) as it demands preserving important information while summarizing the large text into a summary. Extractive and abstractive text summarization are widely investigated approaches for text summarization. In extractive summarization, the important sentence from the large text is extracted and combined to create a summary whereas abstractive summarization creates a summary that is more focused on meaning, rather than content. Therefore, abstractive summarization gained more attention from researchers in the recent past. However, text summarization is still an untouched topic in the Nepali language. To this end, we proposed an abstractive text summarization for Nepali text. Here, we, first, create a Nepali text dataset by scraping Nepali news from the online news portals. Second, we design a deep learning-based text summarization model based on an encoder-decoder recurrent neural network with attention. More precisely, Long Short-Term Memory (LSTM) cells are used in the encoder and decoder layer. Third, we build nine different models by selecting various hyper-parameters such as the number of hidden layers and the number of nodes. Finally, we report the Recall-Oriented Understudy for Gisting Evaluation (ROUGE) score for each model to evaluate their performance. Among nine different models created by adjusting different numbers of layers and hidden states, the model with a single-layer encoder and 256 hidden states outperformed all other models with F-Score values of 15.74, 3.29, and 15.21 for ROUGE-1 ROUGE-2 and ROUGE-L, respectively.
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BOLOCAN, ANDREI SORIN, ELENA ALEXANDRA ONICIUC, AVELINO ALVAREZ-ORDÓÑEZ, MARTIN WAGNER, KATHRIN RYCHLI, KIERAN JORDAN, and ANCA IOANA NICOLAU. "Putative Cross-Contamination Routes of Listeria monocytogenes in a Meat Processing Facility in Romania." Journal of Food Protection 78, no. 9 (September 1, 2015): 1664–74. http://dx.doi.org/10.4315/0362-028x.jfp-14-539.
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Putative routes of Listeria monocytogenes contamination, based on the workflow of the employees, were studied in a meat processing facility by investigating 226 samples collected from food contact surfaces, non–food contact surfaces, raw materials, and ready-to-eat meat products on four occasions over a 1-year period. In total, 19.7% of non–food contact surfaces, 22.9% of food contact surfaces, 45% of raw materials, and 20% of ready-to-eat meat products were positive for L. monocytogenes (analyzed by the International Organization for Standardization standard method ISO 11290). Pulsed-field gel electrophoresis (PFGE) profiles were determined for a representative subset of these isolates, and 11 distinct pulsotypes were identified, two of which were frequently isolated (T4 and T8) and considered persistent. Strains from the various pulsotypes were screened for the presence of bcrABC and qacH, the genes responsible for tolerance responses to quaternary ammonium compounds. Two strains harbored bcrABC, and these strains had a higher benzalkonium chloride tolerance; however, they were not considered persistent strains. The frequently isolated PFGE pulsotype T8 strains were highly adhesive to abiotic surfaces at 10 and 20°C; however, the pulsotype T6 strain, which was isolated only at the last sampling time, had the highest adhesion ability, and the pulsotype T4 strain (the second most persistent pulsotype) had only modest adhesion. Four putative cross-contamination routes were confirmed by mapping the persistent and other isolates. This information could allow a food safety manager to adjust the work flow to improve the hygienic conditions in a meat processing facility. This study revealed the prevalence and persistence of L. monocytogenes strains in a meat processing facility and established the importance of developing strategies to avoid cross-contamination, recalls, and outbreaks of listeriosis.
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Günaydın, Ahmet Can, Ali Rıza Yıldız, and Necmettin Kaya. "Multi-objective optimization of build orientation considering support structure volume and build time in laser powder bed fusion." Materials Testing 64, no. 3 (March 1, 2022): 323–38. http://dx.doi.org/10.1515/mt-2021-2075.
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Abstract Additive manufacturing is a production technology based on creating three-dimensional parts directly from computer-aided design data layer-by-layer. In recent years, it has been used in many industries with the production of functional, high-quality metallic parts with the powder bed fusion process by laser. The build orientation of the three-dimensional part has a major impact on many factors such as part quality, waste amount, production time, and cost. In this study, a multi-objective optimization is carried out using non-dominated sorting genetic algorithm-II to simultaneously optimize different objectives that may conflict with each other, such as the amount of support structure and build time. Estimation methods are developed for computing the amount of support structure and the build time, which reflect the current state of the technology. With the developed method, build orientation is optimized for a complex part, and the wide range of alternative results are visualized and evaluated. The design for additive manufacturing knowledge required to correctly perform the build orientation process is eliminated by automating the pre-processing stage. Therefore, the contribution is made to the accessibility and sustainability of the PBF-L, which has high process costs by minimizing support structure volume and build time.
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Qin, Cifeng, Wenyin Gong, and Xiang Li. "Research on the Image Description Algorithm of Double-Layer LSTM Based on Adaptive Attention Mechanism." Mathematical Problems in Engineering 2022 (May 21, 2022): 1–9. http://dx.doi.org/10.1155/2022/2315341.
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Image text description is a multimodal data processing problem in the computer field, which involves the research tasks of computer vision and natural language processing. At present, the research focus of image text description task is mainly on the method based on deep learning. The work of this paper is mainly focused on the imprecise description of visual words and nonvisual words in the description of image description tasks in the image text description. An adaptive attention double-layer LSTM (long short-term memory) model based on coding-decoding is proposed. Compared with the algorithm based on the adaptive attention mechanism based on the coding-decoding framework, the evaluation index BLEU-1 is improved by 1.21%. The METEOR was 0.75% higher and CIDEr was 0.55%, while the indexes of BLEU-4 and ROUGE-L were not as good as those of the original model, but the index was not different. Although it cannot surpass all the performance indicators of the original model, the description of visual words and nonvisual words is more accurate in the actual image text description.
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Arriafdi, Muhammad Zainuddin, Mohd Helmi Sani, Wan Azlina Ahmad, and Muhd Nazrul Hisham Zainal Alam. "INVESTIGATION ON DOWNSTREAM PROCESSING OF INDUSTRIAL SCALE OF FLEXIRUBIN PRODUCTION USING SUPERPRO DESIGNER." Jurnal Teknologi 83, no. 2 (February 2, 2021): 37–45. http://dx.doi.org/10.11113/jurnalteknologi.v83.14688.
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The aim of this work is to utilize a process simulator SuperPro Designer v5.5 (Intelligent, NJ, USA) for investigation on the most optimum scenario for the recovery of flexirubin pigment that was produced from a fermentation process using Chryseobacterium artocarpi strain. Process flow sheeting was based on the production of 300 kg per annum of flexirubin. Production phase at 1000 L bioreactor (including steps for the inoculum development) and different scenarios/routes for recovery of flexirubin were considered. SuperPro designer process simulator allowed for the computation of overall operating cost and capital cost under various operating parameters. Results from simulation shows that all proposed downstream processing routes is capable of achieving a high degree of flexirubin recovery yield i.e. at least 94% (or greater). Operating cost was relatively low as the overall quantity of flexirubin was rather small. Capital cost for equipment purchasing however highly depending on the selection of unit procedures for recovery of flexirubin. Centrifugation unit accelerated the separation processes but it is costly compared to the dead-end filtration unit. The latter was found to be the bottleneck for the optimization step where high yield of flexirubin can be warranted at reduced capital cost by at least 40%.
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Guan, Zhibin, Kang Liu, Yan Ma, Xu Qian, and Tongkai Ji. "Middle-Level Attribute-Based Language Retouching for Image Caption Generation." Applied Sciences 8, no. 10 (October 9, 2018): 1850. http://dx.doi.org/10.3390/app8101850.
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Image caption generation is attractive research which focuses on generating natural language sentences to describe the visual content of a given image. It is an interdisciplinary subject combining computer vision (CV) and natural language processing (NLP). The existing image captioning methods are mainly focused on generating the final image caption directly, which may lose significant identification information of objects contained in the raw image. Therefore, we propose a new middle-level attribute-based language retouching (MLALR) method to solve this problem. Our proposed MLALR method uses the middle-level attributes predicted from the object regions to retouch the intermediate image description, which is generated by our language generation model. The advantage of our MLALR method is that it can correct descriptive errors in the intermediate image description and make the final image caption more accurate. Moreover, evaluation using benchmark datasets—MSCOCO, Flickr8K, and Flickr30K—validated the impressive performance of our MLALR method with evaluation metrics—BLEU, METEOR, ROUGE-L, CIDEr, and SPICE.
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ZUNABOVIC, M., K. J. DOMIG, I. PICHLER, and W. KNEIFEL. "Monitoring Transmission Routes of Listeria spp. in Smoked Salmon Production with Repetitive Element Sequence-Based PCR Techniques." Journal of Food Protection 75, no. 3 (March 1, 2012): 504–11. http://dx.doi.org/10.4315/0362-028x.jfp-11-341.
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Various techniques have been used for tracing the transmission routes of Listeria species and for the assessment of hygiene standards in food processing plants. The potential of repetitive element sequence-based PCR (Rep-PCR) methods (GTG5 and REPI+II) for the typing of Listeria isolates (n = 116), including Listeria monocytogenes (n = 46), was evaluated in a particular situation arising from the relocation of a company producing cold-smoked salmon. Pulsed-field gel electrophoresis (PFGE) using three restriction enzymes (ApaI, AscI, and SmaI) was used for comparison. Identical transmission scenarios among two companies could be identified by cluster analysis of L. monocytogenes isolates that were indistinguishable by both Rep-PCR and PFGE. The calculated diversity index (DI) indicates that Rep-PCR subtyping of Listeria species with primer sets GTG5 and REPI+II has a lower discrimination power than does PFGE. When concatenated Rep-PCR cluster analysis was used, the DI increased from 0.934 (REPI+II) and 0.923 (GTG5) to 0.956. The discrimination power of this method was similar to that of PFGE typing based on restriction enzyme ApaI (DI = 0.955). Listeria welshimeri may be useful as an indicator for monitoring smoked salmon processing environments. Rep-PCR meets the expectations of a reasonable, fast, and low-cost molecular subtyping method for the routine monitoring of Listeria species. The discriminatory power as characterized by the DI sufficiently quantifies the probability of unrelated isolates being characterized as different subtypes. Therefore, Rep-PCR typing based on two primer systems (GTG5 and REPI+II) may be a useful tool for monitoring industrial hygiene.
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Yousefi, Aryan, and Kalpdrum Passi. "Nemesis: Neural Mean Teacher Learning-Based Emotion-Centric Speaker." Algorithms 16, no. 2 (February 9, 2023): 97. http://dx.doi.org/10.3390/a16020097.
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Image captioning is the multi-modal task of automatically describing a digital image based on its contents and their semantic relationship. This research area has gained increasing popularity over the past few years; however, most of the previous studies have been focused on purely objective content-based descriptions of the image scenes. In this study, efforts have been made to generate more engaging captions by leveraging human-like emotional responses. To achieve this task, a mean teacher learning-based method has been applied to the recently introduced ArtEmis dataset. ArtEmis is the first large-scale dataset for emotion-centric image captioning, containing 455K emotional descriptions of 80K artworks from WikiArt. This method includes a self-distillation relationship between memory-augmented language models with meshed connectivity. These language models are trained in a cross-entropy phase and then fine-tuned in a self-critical sequence training phase. According to various popular natural language processing metrics, such as BLEU, METEOR, ROUGE-L, and CIDEr, our proposed model has obtained a new state of the art on ArtEmis.
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Wazery, Y. M., Marwa E. Saleh, Abdullah Alharbi, and Abdelmgeid A. Ali. "Abstractive Arabic Text Summarization Based on Deep Learning." Computational Intelligence and Neuroscience 2022 (January 11, 2022): 1–14. http://dx.doi.org/10.1155/2022/1566890.
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Text summarization (TS) is considered one of the most difficult tasks in natural language processing (NLP). It is one of the most important challenges that stand against the modern computer system’s capabilities with all its new improvement. Many papers and research studies address this task in literature but are being carried out in extractive summarization, and few of them are being carried out in abstractive summarization, especially in the Arabic language due to its complexity. In this paper, an abstractive Arabic text summarization system is proposed, based on a sequence-to-sequence model. This model works through two components, encoder and decoder. Our aim is to develop the sequence-to-sequence model using several deep artificial neural networks to investigate which of them achieves the best performance. Different layers of Gated Recurrent Units (GRU), Long Short-Term Memory (LSTM), and Bidirectional Long Short-Term Memory (BiLSTM) have been used to develop the encoder and the decoder. In addition, the global attention mechanism has been used because it provides better results than the local attention mechanism. Furthermore, AraBERT preprocess has been applied in the data preprocessing stage that helps the model to understand the Arabic words and achieves state-of-the-art results. Moreover, a comparison between the skip-gram and the continuous bag of words (CBOW) word2Vec word embedding models has been made. We have built these models using the Keras library and run-on Google Colab Jupiter notebook to run seamlessly. Finally, the proposed system is evaluated through ROUGE-1, ROUGE-2, ROUGE-L, and BLEU evaluation metrics. The experimental results show that three layers of BiLSTM hidden states at the encoder achieve the best performance. In addition, our proposed system outperforms the other latest research studies. Also, the results show that abstractive summarization models that use the skip-gram word2Vec model outperform the models that use the CBOW word2Vec model.
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Ledoh, Delfi Yulianti, Alan Ch Sabuna, and Yanti Daud. "PEMANFAATAN TUMBUHAN DALAM PROSES PEWARNAAN KAIN TENUN IKAT DI PULAU NDAO, DESA NDAO NUSE, KABUPATEN ROTE NDAO." Indigenous Biologi : Jurnal Pendidikan dan Sains Biologi 4, no. 2 (August 31, 2021): 37–45. http://dx.doi.org/10.33323/indigenous.v4i2.151.
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ABSTRACT
This study aims to determine the types of natural coloring plants, organs plant or parts used, the processing to the colors produced from plants organs used in the process of coloring woven cloth on Ndao Island, Ndao Nuse Village, Ndao Nuse sub-district, Rote Ndao Regency. The method used is a qualitative descriptive method. The technique used in this study is direct observation techniques in the field and semi-structured interviews. Semi-structured interviews are interview processes that use interview guides derived from the development of topics and ask questions to ikat weaving craftsmen, the aim is to explore and obtain information related to the data needed. Based on the results of research in Ndao Nuse Village, Ndao Nuse sub-district, Rote Ndao Regency, found 5 types of natural coloring plants that are utilized by the Ndao Nuse community in the process of coloring woven cloth, namely tarum (Indigofera tinctoria L) producing black, turmeric rhizome (Curcuma domestica L) producing yellow, legundi (Vitex trifolia L) produces a light yellow color, kedondong fence (Lannea nigratana) produces a brown color, the green color is produced red distance (Jatrhopa gossiphofolia). Parts or organs of plants used are leaves, rhizomes and bark. The process of processing plant parts or organs that are used to produce color includes collision, boiling, and soaking. In addition to the 5 types of plants that are used as basic dyes there are also plants and other additives used in the coloring process are lime, whiting, and alum. The benefits of this additional material are as a color enhancer so that the color produced does not fade easily. Most of the plants that have potential as natural dyes for connective weaving have been cultivated. Plants that are cultivated are tarum, turmeric, and kedondong fence.
Keywords: Weaving, Natural Staining Plants
ABSTRACTThis study aims to determine the types of natural coloring plants, organs plant or parts used, the processing to the colors produced from plants organs used in the process of coloring woven cloth on Ndao Island, Ndao Nuse Village, Ndao Nuse sub-district, Rote Ndao Regency. The method used is a qualitative descriptive method. The technique used in this study is direct observation techniques in the field and semi-structured interviews. Semi-structured interviews are interview processes that use interview guides derived from the development of topics and ask questions to ikat weaving craftsmen, the aim is to explore and obtain information related to the data needed. Based on the results of research in Ndao Nuse Village, Ndao Nuse sub-district, Rote Ndao Regency, found 5 types of natural coloring plants that are utilized by the Ndao Nuse community in the process of coloring woven cloth, namely tarum (Indigofera tinctoria L) producing black, turmeric rhizome (Curcuma domestica L) producing yellow, legundi (Vitex trifolia L) produces a light yellow color, kedondong fence (Lannea nigratana) produces a brown color, the green color is produced red distance (Jatrhopa gossiphofolia). Parts or organs of plants used are leaves, rhizomes and bark. The process of processing plant parts or organs that are used to produce color includes collision, boiling, and soaking. In addition to the 5 types of plants that are used as basic dyes there are also plants and other additives used in the coloring process are lime, whiting, and alum. The benefits of this additional material are as a color enhancer so that the color produced does not fade easily. Most of the plants that have potential as natural dyes for connective weaving have been cultivated. Plants that are cultivated are tarum, turmeric, and kedondong fence. Keywords: Weaving, Natural Staining Plants
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Shi, Tong, Xiaohui Li, Zhonglin Liu, and Licai Wang. "Research on Bi-LSTM machine reading comprehension algorithm based on attention mechanism." Journal of Physics: Conference Series 2258, no. 1 (April 1, 2022): 012007. http://dx.doi.org/10.1088/1742-6596/2258/1/012007.
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Abstract Machine reading comprehension is a very important research field in Natural Language Processing (NLP), but it is not sufficient for military research, and traditional machine reading comprehension algorithms do not fully explore every word in different contexts. In response to the above problems, this paper proposes a machine reading comprehension model that incorporates a multi-attention mechanism. It is brave to solve machine reading comprehension tasks in the military field. The model in this paper performs word embedding, part-of-speech embedding, and knowledge base embedding for each word in the article. Among them, knowledge embedding uses military knowledge bases to make up for the lack of information on military entities and relationships in military articles, and independently carries out part-of-speech embedding to solve the problem of part of speech judgment of polysemous words in specific contexts. The experimental results show that the machine reading comprehension model with multi-attention mechanism proposed in this paper can achieve better results on machine reading comprehension tasks, and the accuracy rate is improved by 1.6% compared with ROUGE-L.
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Zuo, Yan Rui, Zhi Yuan Rui, Rui Cheng Feng, De Chun Luo, and Chang Feng Yan. "Influence of Microstructure and Stress Ratio on Fatigue Crack Propagation in TiAl Alloy." Advanced Materials Research 881-883 (January 2014): 1330–33. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1330.
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Based on the fatigue crack propagation experiments did by A.-L. Gloanec et al., the fatigue crack propagation rates of TiAl alloy of two processing routes, namely casting and PM, and stress ratios had been tested, in order to find out the effects of microstructure and stress ratio. An improved fatigue crack propagation formula for region Ⅱ (the expansion region) was derived according to Paris formula. The specific values of the constants in the formula were calculated. Fatigue crack propagation resistance of nearly fully lamellar microstructure is superior to that of equiaxed γ grain. The experimental results present that both microstructure and stress ratio has a significant influence on fatigue crack growth rate.
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Acharya, Rabinarayan, Channappa R. Harisha, and Siba P. Rout. "Pharmacognostical Evaluation of Raw and Shodhita (Processed) Danti [Baliospermum montanum (Willd.) Muell.-Arg] Root." Journal of Drug Research in Ayurvedic Sciences 2, no. 3 (2017): 164–74. http://dx.doi.org/10.5005/jp-journals-10059-0016.
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ABSTRACT Introduction Danti, Baliospermum solanifolium (Burm.) Suresh [Syn. Baliospermum montanum (Willd.) Muell. Arg], of family Euphorbiaceae is an important herbal drug in the Ayurveda pharmacopoeia of India. In Ayurveda, Samskara (processing) has been shown to increase the efficacy of various drugs. Shodhana (purificatory measures/processing) is one of the steps involved in Samskara. The Charaka samhita describes the Shodhana (processing) of Danti by applying the fruit powder of Pippali (Piper longum L.) along with honey, wrapping it with Kusha (Desmostachya bippinnata Stapf.), and then fomenting it. The root thus obtained is dried under sunrays and then stored for further use. The exact pharmacognostical changes that transpire through Samskara (classical processing technique) remain to be explored scientifically. Hence, an attempt has been made to evaluate the pharmacognostical changes in Danti root, including its powder microscopy. Materials and methods Roots of raw Danti (RD) were collected from its natural habitat (Odisha) after proper botanical authentication. The roots were subjected to Shodhana and four groups of Danti root—RD, classically processed Danti root (CPDR), Kusha-processed Danti root (KPDR), and water-classically processed Danti root (WPDR)—were obtained. The raw and classically processed Danti roots were evaluated for their macroscopic and microscopic characters while RD, CPDR, KPDR, and WPDR were subjected to powder microscopy. The macroscopic powder images of the respective Danti samples was carried out by L*a*b*color-based image segmentation for identification. Results Transverse sections (TS) of CPDR show characteristic features with multilayered, ruptured reddish cork cells and presence of black debris of Pippali adhering to cork cells. Powder microscopy reveals Pippali with stone cells and dark-brownish oleoresin content in the CPDR group. WPDR reveals more swollen sclereids compared with the KPDR group. Macroscopic imaging showed distinct L*a*b* color-based segmentation. Conclusion Pharmacognostical findings of raw and shodhita Danti root will serve as a reference material for future scientific investigation. How to cite this article Rout SP, Harisha CR, Acharya R. Pharmacognostical Evaluation of Raw and Shodhita (Processed) Danti [Baliospermum montanum (Willd.) Muell.-Arg] Root. J Drug Res Ayurvedic Sci 2017;2(3):164-174.
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Chen, Xiaomin, Di Wang, Jingming Mai, Xiaojun Chen, and Wenhao Dou. "High-Efficient Micro Reacting Pipe with 3D Internal Structure: Design, Flow Simulation, and Metal Additive Manufacturing." Applied Sciences 10, no. 11 (May 29, 2020): 3779. http://dx.doi.org/10.3390/app10113779.
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The micro reacting pipe with 3D internal structure, which is a micromixer with the shape of the pipe, has shown great advantages regarding mass transfer and heat transfer. Since the fluid flow is mostly laminar at the micro-scale, which is unfavorable to the diffusion of reactants, it is important to understand the influence of the geometry of the microchannel on the fluid flow for improving the diffusion of the reactants and mixing efficiency. On the other hand, it is a convenient method to manufacture a micro reacting pipe in one piece through metal additive manufacturing without many post-processing processes. In this paper, a basis for the design of a micromixer model was provided by combining the metal additive manufacturing process constraints with computational fluid dynamics (CFD) simulation. The effects of microchannel structures on fluid flow and mixing efficiency were studied by CFD simulation whose results showed that the internal micro-structure had a significantly positive effect on the mixing efficiency. Based on the simulation results, the splitting-collision mechanism was discussed, and several design rules were obtained. Two different materials were selected for manufacturing with the laser powder bed fusion (L-PBF) technology. After applying pressure tests to evaluate the quality of the formed parts and comparing the corrosion-resistance of the two materials, one material was picked out for the industrial application. Additionally, the chemical experiment was conducted to evaluate the accuracy of the simulation. The experimental results showed that the mixing efficiency of the micro reacting pipe increased by 56.6%, and the optimal determining size of the micro reacting pipe was 0.2 mm. The study can be widely used in the design and manufacture of a micromixer, which can improve efficiency and reacting stability in this field.