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Artykuły w czasopismach na temat "Ferric Order Parameters"
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Venegas-García, Deysi J., i Lee D. Wilson. "Kinetics and Thermodynamics of Adsorption for Aromatic Hydrocarbon Model Systems via a Coagulation Process with a Ferric Sulfate–Lime Softening System". Materials 16, nr 2 (10.01.2023): 655. http://dx.doi.org/10.3390/ma16020655.
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The adsorption mechanisms for model hydrocarbons, 4-nitrophenol (PNP), and naphthalene were studied in a coagulation-based process using a ferric sulfate–lime softening system. Kinetic and thermodynamic adsorption parameters for this system were obtained under variable ionic strength and temperature. An in situ method was used to investigate kinetic adsorption profiles for PNP and naphthalene, where a pseudo-first order kinetic model adequately described the process. Thermodynamic parameters for the coagulation of PNP and naphthalene reveal an endothermic and spontaneous process. River water was compared against lab water samples at optimized conditions, where the results reveal that ions in the river water decrease the removal efficiency (RE; %) for PNP (RE = 28 to 20.3%) and naphthalene (RE = 89.0 to 80.2%). An aluminum sulfate (alum) coagulant was compared against the ferric system. The removal of PNP with alum decreased from RE = 20.5% in lab water and to RE = 16.8% in river water. Naphthalene removal decreased from RE = 89.0% with ferric sulfate to RE = 83.2% with alum in lab water and from RE = 80.2% for the ferric system to RE = 75.1% for alum in river water. Optical microscopy and dynamic light scattering of isolated flocs corroborated the role of ions in river water, according to variable RE and floc size distribution.
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Arrieta, Alberto Albis, Ever Ortiz Muñoz, Ismael Piñeres Ariza, Juan Osorio Cardozo i Jennifer Monsalvo Morales. "Catalytic effect of ferric sulfate and zinc sulfate on lignin pyrolysis". Applied Chemical Engineering 5, nr 1 (26.04.2022): 59. http://dx.doi.org/10.24294/ace.v5i1.1449.
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The effect of zinc sulfate and ferric sulfate on the pyrolysis process of lignin was studied at three different heating rates by using the thermogravimetric analysis technique. It was found that the pyrolysis of pure lignin is barely affected with the change of heating rates between 10 to 100 °C/min, which is unexpected because of the kinetic nature of pyrolysis. The pyrolysis kinetics of this major component of biomass was studied by using three fitting methods: the differential method with reaction order model n, the isoconversional method, and the distribution of activation energies model, DAEM. The best fit, which allowed calculating acceptable kinetic parameters, was obtained using the last method. The results show the influence of the catalysts and the heating rate on the lignin pyrolysis processes in the presence of the sulfates under study, which is confirmed by obtaining different kinetic parameters. The results suggest that zinc sulfate and ferric sulfate change the kinetic mechanism of lignin pyrolysis.
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Nagano, Tetsushi, Hiroshi Isobe, Satoru Nakashima i Midori Ashizaki. "Characterization of Iron Hydroxides in a Weathered Rock Surface by Visible Microspectroscopy". Applied Spectroscopy 56, nr 5 (maj 2002): 651–57. http://dx.doi.org/10.1366/0003702021955222.
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In order to nondestructively characterize chemical forms of ferric hydroxides in weathered rock, charge-coupled device type visible microspectroscopy was applied to brown stains produced in weathered granite surfaces. The combination of visible microspectra and color parameters ( a* and b*) was effective in examining chemical forms of ferric hydroxides in the analytical area. Color parameters in an a*– b* diagram of the brown stains, mostly lying between goethite and ferrihydrite trends, indicated that the brown stains contain ferrihydrite or hematite in addition to goethite. Similarity of the visible microspectra of the brown stains and their first derivatives to those of goethite or ferrihydrite suggests that goethite and/or ferrihydrite are the main weathering products of the granite. Occurrence of ferrihydrite as well as goethite in the brown stains implies that crystallization of ferrihydrite to goethite might be hindered during the granite weathering. This fact suggests the possibility of toxic metal retention in ferrihydrite by its long-term persistence during water–rock interactions at the earth's surface.
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Zhu, Weixiao, Jianduo Wang, Yili Wang i Hongjie Wang. "Study on sulfadimethoxine removal from aqueous solutions by hydrous ferric oxides". Water Science and Technology 74, nr 5 (21.06.2016): 1136–42. http://dx.doi.org/10.2166/wst.2016.246.
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Significant concerns have been raised over the presence of antibiotics including sulfadimethoxine (SDMO) in aquatic environments. This study investigated the removal capability and mechanism involved in the removal of SDMO by hydrous ferric oxides (HFO). Results showed that SDMO removal was highly pH and ionic strength dependent. The pseudo-first-order model fitted well the kinetic results, and the value of the calculated activation energy for SDMO adsorption onto HFO was 8.6 kJ mol−1. Adsorption isotherms at varied temperatures were well described by the Langmuir model. Thermodynamic parameters (change in enthalpy > 0, change in entropy > 0, and change in Gibbs free energy < 0) calculated from the temperature-dependent sorption data revealed spontaneous and endothermic process. The exchange of the surface hydroxyl groups of HFO and the negative anions of SDMO− and the electrostatic interaction between the positively charged surface of HFO and the deprotonated imino (–N−–) accounted for the uptake of SDMO by HFO.
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Jafari, Shila, Benjamin Wilson, Minna Hakalahti, Tekla Tammelin, Eero Kontturi, Mari Lundström i Mika Sillanpää. "Recovery of Gold from Chloride Solution by TEMPO-Oxidized Cellulose Nanofiber Adsorbent". Sustainability 11, nr 5 (6.03.2019): 1406. http://dx.doi.org/10.3390/su11051406.
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The goal of this study was to assess the sustainability of a modified cellulose nanofiber material for the recovery of precious gold from chloride solution, with a special focus on gold recovery from acidic solutions generated by cupric and ferric chloride leaching processes. TEMPO-oxidized cellulose nanofiber in hydrogel (TOCN), dry (H-TOCN, F-TOCN) and sheet form (S-TOCN) was examined for gold adsorptivity from chloride solution. Additionally, this work describes the optimum conditions and parameters for gold recovery. The data obtained in this investigation are also modeled using kinetic (pseudo first-order and pseudo second-order), isotherm best fit (Freundlich, Langmuir and Langmuir-Freundlich), and thermodynamic (endothermic process) parameters. Results demonstrate that high levels of gold removal can be achieved with TEMPO-oxidized cellulose nanofibers (98% by H-TOCNF) and the interaction characteristics of H-TOCN with gold suggests that other precious metals could also be efficiently recovered.
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Bhattarai, Pushpa, Khagendra Prasad Bohra i Megh Raj Pokhrel. "Adsorptive Removal of As(III) from Aqueous Solution". Journal of Institute of Science and Technology 19, nr 1 (8.11.2015): 150–54. http://dx.doi.org/10.3126/jist.v19i1.13841.
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The iron-modified Dalbergia sissoo sawdust was synthesized by loading iron (III) onto phosphorylated Dalbergia sissoo sawdust via soaking in a ferric salt solution. Batch studies were performed at an initial concentration of 1 mg/l to evaluate the effect of parameters such as pH, equilibrium time, adsorbent dose and concentration of adsorbate. Kinetics and isotherm modeling studies demonstrated that the experimental data best fit a pseudo-first order and Langmuir isotherm model, respectively. The maximum adsorption capacity was found to be 1.33 mg/g for As(III) onto FePDSD suggesting the suitability of chemically modified Dalbergia sissoo sawdust for the adsorptive removal of As(III) from aqueous solution.Journal of Institute of Science and Technology, 2014, 19(1): 150-154
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Malki, Fatiha, Ali Alouache i Soumia Krimat. "Effects of Various Parameters on the Antioxidant Activities of the Synthesized Heterocyclic Pyrimidinium Betaines". Indonesian Journal of Chemistry 23, nr 1 (27.12.2022): 90. http://dx.doi.org/10.22146/ijc.74803.
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Betaine derivatives are widely used in cosmetic, industrial uses, biology and other scientific fields. Pyrimidinium betaine is a special class of bioactive heterocyclics. They have interesting antioxidant and free radical scavenging activities. This work aims to examine the influence of some parameters on the antioxidant activity of some synthesized betaines containing pyrimidine ring. Four pyrimidinium betaines: monocyclic, bicyclics, and one with a fatty alkyl chain were synthesized from condensation of 2-aminopyrimidine or amidine derivatives with malonic esters, and their antioxidant capacity was evaluated. The effects of concentration, reaction time and temperature on their antioxidant activities were investigated by three common methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging, ferric reducing antioxidant power (FRAP) and β-carotene bleaching. The results showed that all pyrimidinium betaines exhibited antioxidant activities in different assays. In the DPPH and reducing power assays, antioxidant activity increased with concentration, whereas in the β-carotene/linoleic acid system, it increased with temperature. On the other hand, the DPPH assay showed an increase in antioxidant capacity over time, while the β-carotene bleaching assay showed a decrease. These results indicate that the antioxidant activity differs depending on the method used and that the various factors affect the antioxidant activity in a different order.
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Harrat, Zouaoui R., Mohammed Chatbi, Baghdad Krour, Marijana Hadzima-Nyarko, Dorin Radu, Sofiane Amziane i Mohamed Bachir Bouiadjra. "Modeling the Thermoelastic Bending of Ferric Oxide (Fe2O3) Nanoparticles-Enhanced RC Slabs". Materials 16, nr 8 (12.04.2023): 3043. http://dx.doi.org/10.3390/ma16083043.
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Nanoparticles, by virtue of their amorphous nature and high specific surface area, exhibit ideal pozzolanic activity which leads to the formation of additional C-S-H gel by reacting with calcium hydroxide, resulting in a denser matrix. The proportions of ferric oxide (Fe2O3), silicon dioxide (SiO2), and aluminum oxide (Al2O3) in the clay, which interact chemically with the calcium oxide (CaO) during the clinkering reactions, influence the final properties of the cement and, therefore, of the concrete. Through the phases of this article, a refined trigonometric shear deformation theory (RTSDT), taking into account transverse shear deformation effects, is presented for the thermoelastic bending analysis of concrete slabs reinforced with ferric oxide (Fe2O3) nanoparticles. Thermoelastic properties are generated using Eshelby’s model in order to determine the equivalent Young’s modulus and thermal expansion of the nano-reinforced concrete slab. For an extended use of this study, the concrete plate is subjected to various mechanical and thermal loads. The governing equations of equilibrium are obtained using the principle of virtual work and solved using Navier’s technique for simply supported plates. Numerical results are presented considering the effect of different variations such as volume percent of Fe2O3 nanoparticles, mechanical loads, thermal loads, and geometrical parameters on the thermoelastic bending of the plate. According to the results, the transverse displacement of concrete slabs subjected to mechanical loading and containing 30% nano-Fe2O3 was almost 45% lower than that of a slab without reinforcement, while the transverse displacement under thermal loadings increased by 10%.
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Ahmed, S., i S. K. Saha. "Electrochemical study of the reaction between progressively alkylated thiazine leucodyes and Fe(III) on a glassy carbon electrode". Canadian Journal of Chemistry 74, nr 10 (1.10.1996): 1896–902. http://dx.doi.org/10.1139/v96-213.
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An electrochemical investigation on five progressively alkylated thiazine dyes in the presence of Fe(III) ions is reported. The theory of the catalytic regeneration mechanism involving an electrode reaction followed by a coupled chemical reaction is applied to derive kinetic parameters of homogeneous reaction. The second-order rate constant for the reaction of thiazine leucodyes with Fe(III) ions was found to increase from 0.25 × 104 to 1.6 × 104 dm3 mol−1 s−1 upon monomethylation and to vary from 0.7 × 104 for the dimethyl derivative to 1.4 × 104 dm3mol−1 s−1 for the tetramethyl one. The electron-donating nature as well as the hydrophobic characteristics of the methyl group influence the kinetics of the homogeneous reaction. Key words: cyclic voltammetry, thiazine dyes, ferric ion, catalytic regeneration, kinetics
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Aguirre, Paulina, Esvar Diaz i Juan C. Gentina. "Evaluation of Parameters in the Bio-Oxidation Process of Refractory Gold Minerals". Advanced Materials Research 825 (październik 2013): 364–67. http://dx.doi.org/10.4028/www.scientific.net/amr.825.364.
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The mining districts located in the western mountain range in the south of Ecuador have gold minerals with refractory characteristics, which do not allow gold recovery by traditional methods used in Ecuador. Therefore, it is necessary to apply some technology that permits to obtain greater metal recovery. Bio-oxidation, as treatment of refractory ores that contain low grade of gold, offers an economic and sustainable alternative for this purpose. The objective of this research was to evaluate the effect of particle size, pulp density and concentration of inoculum and inducer (Fe+2) on the bio-oxidation of refractory gold minerals in order to maximize gold recovery of the bioleached minerals by means of a cyanidation process. The microbial consortium used in this work was collected and isolated from the Portovelo mining district corresponding mostly toAcidithiobacillus ferrooxidansandLeptospirillum ferrooxidansspecies. The Eh, final concentration of ferric ion, total iron and sulfates were measured. Finally, the bio-oxidized material was tested using cyanidation to determine the gold recovery. The results after the cyanidation tests showed that the highest gold recovery was obtained when the bio-oxidation step was conducted with 68-91 µm particle size, 15% pulp density, 20% v/v inoculum and 2 g/L of Fe2+as inducer. At those conditions, gold recovery was 68% compared to 26% obtained when no bio-oxidation step was performed, demonstrating that this process was favorable compared with traditional gold recovery processes
Części książek na temat "Ferric Order Parameters"
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Kastali, Mlika, Latifa Mouhir, Abdelaziz Madinzi, Abdeslam Taleb, Abdelkader Anouzla i Salah Souabi. "Reducing Pollution of Stabilized Landfill Leachate by Mixing of Coagulants and Flocculants: A Comparative Study". W Environmental Management [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97253.
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The physico-chemical process of coagulation-flocculation is very efficient and economical for the treatment of leachate. The latter can have considerable impacts on the environment. The leachate from the landfill of the city of Mohammedia is characterized by a high COD content which varies between 2200 and 2700 mg/l, a total Kjeldahl nitrogen concentration varying from 1080 to 1405 mg/l while the ammonium content has a concentration varying between 587 and 1410 mg/l. Organic matter is not readily biodegradable (BOD5/COD: 0.2 to 0.13). Metal concentrations ranged from 0.1 to 4.2 mg/l for Cr, 40 to 5 mg/l for Cd, and 0.3 to 0.8 mg/l for lead. For monitoring the leachate treatment, several coagulants and flocculants were used (FeCl3, Al2(SO4)3, Alginate, cationic flocculants, anionic flocculants). In parallel with the monitoring of the physicochemical parameters we followed the production of the volume of the settled sludge over time. Treatment with all coagulants and flocculants used is pH dependent. Ferric Chloride has been shown to be effective at a pH of 6.5 while for Aluminum Sulfate the optimum pH is 5.3. The results showed that coagulation-flocculation by Ferric Chloride and Aluminum Sulfate is very effective in reducing turbidity. This reduction reaches 95 and 98% respectively for FeCl3 and Al2(SO4)3, while the reduction in COD for the two coagulants is around 60%. Organic flocculants alone do not lead to a significant reduction in turbidity and COD, while their combination with coagulants marks a good reduction in pollution. Hydrated iron hydroxides precipitate more easily than flocs formed by aluminum, resulting in more efficient removal of pollutants than that obtained at lower pH values. The order of introduction strongly influences the coagulation flocculation. The optimal doses of the various coagulants and flocculants chosen for the study vary from one reagent to another. FeCl3 remains the most suitable coagulant to further eliminate organic and metal pollution. The cost associated with the treatment using flocculants remains much higher when the flocculant is used in admixture with a coagulant.
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D.R. Mackinnon, Ian, Alanoud Almutairi i Jose A. Alarco. "Insights from Systematic DFT Calculations on Superconductors". W Real Perspective of Fourier Transforms and Current Developments in Superconductivity. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.96960.
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We present three systematic approaches to use of Density Functional Theory (DFT) for interpretation and prediction of superconductivity in new or existing materials. These approaches do not require estimates of free parameters but utilize standard input values that significantly influence computational resolution of reciprocal space Fermi surfaces and that reduce the meV-scale energy variability of calculated values. Systematic calculations on conventional superconductors show that to attain a level of resolution comparable to the energy gap, two key parameters, Δk and the cut-off energy, must be optimized for a specific compound. The optimal level of resolution is achieved with k-grids smaller than the minimum reciprocal space separation between key parallel Fermi surfaces. These approaches enable estimates of superconducting properties including the transition temperature (Tc) via (i) measurement of the equivalent thermal energy of a phonon anomaly (if present), (ii) the distribution of electrons and effect on Fermi energy (EF) when subjected to a deformation potential and (iii) use of parabolic, or higher order quartic, approximations for key electronic bands implicated in electron–phonon interactions. We demonstrate these approaches for the conventional superconductors MgB2, metal substituted MgB2 and boron-doped diamond.
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Sumalatha, Edapalli, Dachepalli Ravinder, Nyathani Maramu, Shubha, Butreddy Ravinder Reddy, Sadhana Katlakunta, Koteswari Gollapudi i Rajender Thota. "Crystal Chemistry, Rietveld Analysis, Structural and Electrical Properties of Cobalt-Erbium Nano-Ferrites". W Ferrite [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98864.
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Synthesis of Cobalt-Erbium nano-ferrites with formulation CoErxFe2-xO4 (x = 0, 0.005, 0.010, 0.015, 0.020, 0.025, and 0.030) using technique of citrate-gel auto-combustion was done. Characterization of prepared powders was done by using XRD, EDAX, FESEM, AFM and FTIR Spectroscopy, DC resistivity properties respectively. XRD Rietveld Analysis, SEM, TEM and EDAX analysis were taken up in studying spectral, structural, magnetic and electrical properties. XRD pattern of CEF nano particles confirm single phase cubic spinal structure. The structural variables given by lattice constant (a), lattice volume (v), average crystallite size (D) and X-ray density(dx), Bulk density (d), porosity (p), percentage of pore space (P%), surface area (s), strain (ε), dislocation density (δ), along with ionic radii, bond length and hoping length were calculated. SEM and TEM results reveal homogeneous nature of particles accompanied by clusters having no impurity pickup. TEM analysis gives information about particle size of nanocrystalline ferrite while EDAX analysis confirm elemental composition. Emergence of two arch shaped frequency bands (ν1 and ν2) that represent vibrations at tetrahedral site (A) and octahedral site(B) was indicated by spectra of FTIR. The samples electrical resistivity (DC) was measured between 30°C -600°C with Two probe method. XRD Rietveld analysis confirm crystallite size lying between 20.84 nm–14.40 nm while SEM analysis indicate formation of agglomerates and TEM analysis indicate particle size ranging between 24 nm–16 nm. DC Electrical measurements indicate continuous decrease in resistivity with increasing temperature while increasing doping decreases curie temperature. The Magnetic parameters such as Saturation magnetization (Ms), Remanent magnetization (Mr), Coercivity (Hc) and Squareness ratio (R = Mr/Ms), Magnetic moment (nB) were altered by doping of Er+3 content in the increasing order (x = 0.00 to 0.030). The increasing erbium content decreases magnetization thus converting the sample into soft magnetic material. Observations indicated strong dependence of magnetic properties on Erbium substitution and coercivity varies in accordance with anisotropy constant. Due to the presence of magnetic dipole Erbium substituted cobalt ferrites can be used in electromagnetic applications. The present study investigates the effect of different compositions of Er3+ replaced for Fe on structural properties and electrical resistivity of cobalt ferrites.
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Mandal, Satish Kumar, Savita, Pradip Kumar Priya, Ram Pratap Yadav, Hari Pratap Bhasker, Raj Kumar Anand i Amreesh Chandra. "A Detailed Study of Structural, Dielectric and Luminescence Properties of Sm3+ Doped BiFeO3 Nanoceramics". W Materials Science: A Field of Diverse Industrial Applications, 110–19. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815051247123010008.
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Observation of at least two coexisting switchable ferroic states viz., ferromagnetic, ferroelectric, and/or ferroelastic at room temperature with promising coupling among order parameters, has made BiFeO3 a highly explored material in the field of multiferroics and/or magnetoelectric multiferroics, which creates the possibility for its application in various technological devices such as spintronics, spin-valve, DRAM, actuators, sensors, solar-cells photovoltaic, etc. Intrinsically, its low coupling coefficients, difficulty to prepare in pure phase in bulk, high leakage current, etc. have restricted BiFeO3 from technological reliability. However, the effect of doping with iso- and alio-valent ions, nanostructure, thin-film-form and nanoparticles, etc., has been carried out to improve its physical properties by several research groups over the decades. In this chapter, the structural, luminescence, and dielectric properties of samarium (Sm3+) doped BiFeO3 nanoceramics synthesized using a modified gelcombustion route are discussed in detail. The effect of Sm3+ doping in BiFeO3 is explored using the X-ray diffraction (XRD) technique. The XRD studies exhibit a possible structural phase transition above Sm3+ doping of 15% from rhombohedral (R3c) space group to the orthorhombic (Pbnm) space group. The dielectric study shows interesting behavior accompanied by structural transition. Our study suggests that Sm3+ doping plays an important role in governing the structural, luminescence, and dielectric properties of BiFeO3 samples.
Streszczenia konferencji na temat "Ferric Order Parameters"
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Hu, Peng-fei, Yong Li, Li-hua Cao i Tao Zhang. "Analysis on Solid Particle Erosion in the Governing Stage of a High-Parameter Steam Turbine". W ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63946.
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The solid particle erosion (SPE) of flow passage is a universal problem in modern high-parameter steam turbines. With the continuous improvement of the working parameters of the steam turbine, the problem of SPE is becoming more serious. This problem is caused by the ferric oxide exfoliations carried by steam from the inner wall of the boiler tube into the steam turbine flow passage, causing the stator blades, the rotor blades, and the shroud to be eroded under impingement and scuffing failure. The SPE cannot only destroy the blade profile, increase the roughness of the blade surface, and affect the aerodynamic performance of the blade, but it can also shorten the maintenance cycle, prolong the maintenance downtime, and even increase the cost for steam turbine maintenance thereby reducing the unit efficiency and safety. In order to simulate SPE in the governing stage of a high-parameter steam turbine, this study adopts the Lagrange method and the Finnie erosion model. The motion characteristics of five different kinds of solid particle, including the solid particle trajectory, are thoroughly analyzed. The regulation of the erosion distribution in the radial and axial directions to the stator and rotor blades is studied to present the mechanism of SPE. Simulated results show that before their collision with the blades, the particles of the small diameters flow with the main stream, and their trajectories are close to the steam streamlines. By contrast, the particles of the large diameters are hardly influenced by the external factors, and their trajectories are close to the straight line. The SPE distribution of the stator and rotor blades varies with the particle diameter. The eroded area in the stator blade is mainly located at the leading edge and the pressure surface, particularly the mid-rear part of the pressure surface, whereas no eroded area can be observed in the suction surface. The small particles greatly affect the erosion distribution of the stator blade. The eroded area in the rotor blade is primarily at the mid-rear part of the pressure surface and the suction surface, which is close to the leading edge. The eroded area takes on a typical slop shape, and the erosion position has an obvious upward trend. The proposed research reveals both the motion characteristics of the solid particles and the distribution regulation of the SPE in the steam turbine flow passage. The analysis results provide references for the governing stage of a high-parameter steam turbine to prevent SPE.
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AYDINER, I. U. "Micromechanical modeling of failure in dual phase steels". W Material Forming. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902479-156.
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Abstract. Having brittle martensitic islands diffused in a ductile ferrite matrix, dual-phase (DP) steels are known for their high formability and favorable material properties. Although they have already proven their advantages in the industry, there are still discussions regarding their microstructure-macroscopic response link. In order to effectively exploit their advantages and analyze their ductility in metal forming operations, the failure mechanisms of DP steels must be well examined following a micromechanics-based approach. There are a number of failure mechanisms to be addressed at the micro scale such as ferrite-martensite and ferrite-ferrite interface decohesion as well as martensite cracking depending on the different microstructural parameters and stress state. A crystal plasticity based finite element framework for RVE calculations is followed here based on the previous work which focuses solely on the plastic deformation (see [1]). Isotropic J2 plasticity model is employed for the hard martensite phase while the rate-dependent crystal plasticity framework is used for the ductile ferrite phase. Cohesive zone elements are inserted at the ferrite-martensite and ferrite-ferrite interfaces for intergranular cracking analysis, besides, intragranular cracking in martensite phase is addressed through an uncoupled damage model. First, a preliminary study was performed in order to identify and calibrate aforementioned failure models, then, various 3D polycrystalline RVEs having different microstructural parameters loaded with different stress triaxialities are analyzed and discussed adding up to the preliminary discussions presented in [2].
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Nabavi, Yasser, Sander M. Calisal, Ayhan Akinturk i Voytek Klaptocz. "A Computational Investigation of the Effect of Geometric Parameters on the Discharge Rate of a Ship Opening". W 25th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2006. http://dx.doi.org/10.1115/omae2006-92404.
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The purpose of the research was to find a relationship between the geometric characteristics of an opening on deck and the water discharge rate. This study is aimed at the stability of open deck ferries and fishing vessels. The effective parameters on the discharge rate are the beam, depth of the water collected on the deck, and the discharge gap height. In this study, CFD analyses for water discharge from a ship deck were conducted, and the commercial code FLUENT was used to conduct the simulations. A two dimensional unsteady 2nd order solver in time and space was used for the simulation. The two-phase free surface model was simulated by the Volume of Fluid (VOF) method. Using the water discharge, the instantaneous depth Froude number was calculated as a part of the non-dimensional simulation. The effect of geometric parameters on the water discharge rate was investigated by keeping two parameters fixed while changing the third parameter. For each parameter, three different values were evaluated and the comparisons of all the twenty seven possible combinations of the effective parameters were presented. Results were compared with the experimental results obtained earlier at UBC.
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Uddin, M. F., R. E. Kurth, C. Sallaberry, G. M. Wilkowski, F. W. Brust i D. Rudland. "Critical Flaw Evaluation of Cast Austenitic Stainless Steel: Deterministic and Probabilistic Fracture Analyses". W ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63850.
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Toughness reduction in cast austenitic stainless steels (CASS) due to thermal embrittlement is a growing concern for flaw tolerance evaluation in nuclear power plants. As the fracture toughness diminishes due to thermal-aging, some aged CASS materials have the potential to reach much lower toughness values than at the beginning of life. CASS also shows a high variability in toughness even for a given chemical composition, operating temperature, ferrite number or chrome equivalent. This is mainly due to the combined ferritic and austenitic microstructure and potentially large grain sizes. This variability in toughness needs to be used when developing flaw evaluation criteria in Section XI of the ASME Boiler and Pressure Vessel Code. In this work, deterministic critical flaw size evaluations were conducted for one of the low-toughness CASS materials with a ferrite number (FN) lower than 25. Six different methods were used to evaluate the critical flaw sizes for circumferential surface flaws. In order to account for the large variability in CASS material properties, a probabilistic fracture mechanics (PFM) procedure was developed. Based on all deterministic analyses, the Dimensionless Plastic-Zone Parameter analysis was used to perform the probabilistic critical flaw evaluation. As an example calculation, an actual toughness distribution from a single US PWR plant chemical composition (using a thermal-aging model) was used to perform the probabilistic analysis. The probabilistic analysis provides the critical flaw sizes at various stress ratios for Service Level A (10−6) and Service Level B (10−5) probability of failure for this particular case.
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Bouchenot, Thomas, Bassem Felemban, Cristian Mejia i Ali P. Gordon. "Application of Ramberg-Osgood Plasticity to Determine Cyclic Hardening Parameters". W ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59317.
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Critical components of modern turbomachinery are frequently subjected to a myriad of service conditions that include diverse mechanical loads at elevated temperatures. The cost, applicability, and accuracy of either numerical or analytical component-level simulations are largely dependent on the material model chosen for the application. A non-interaction (NI) model derived from individual elastic, plastic, and creep components is developed in this study. The candidate material under examination for this application is 2.25Cr-1Mo, a low-alloy ferritic steel commonly used in chemical processing, nuclear reactors, pressure vessels, and power generation. Data acquired from literature over a range of temperatures up to 650°C are used to calibrate the creep and plastic components described using constitutive models generally native to general-purpose FEA. Traditional methods invoked to generate coefficients for advanced constitutive models such as non-linear kinematic hardening employ numerical fittings of hysteresis data, which result in values that are neither repeatable nor display reasonable temperature-dependence. By extrapolating simplifications commonly used for reduced-order model approximations, an extension utilizing only the cyclic Ramberg-Osgood coefficients has been developed to identify these parameters. Unit cell simulations are conducted to verify the accuracy of the approach. Results are compared with isothermal and non-isothermal literature data.
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Kim, Dong-Hak, Jeong-Hyun Lee i Ki-Ju Kang. "An Experimental Method to Measure Q-Parameter for Two Parameter Theory of Ductile Fracture". W ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41867.
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In the two parameter approaches, one of the second parameters, T-stress, Q and A2 is used together with J-integral to describe the constraint loss near the crack tip under large scale yielding states. Among the second parameters, Q seems to be most promising from a practical point of view because it applies for three-dimensional geometries. In order to determine the Q for a given geometry and load, however, three-dimensional elastic-plastic finite element analysis, which is time consuming and costly, has had to be performed so far. In this work an experimental method to measure Q-parameter insitu is described. The basic idea comes from the fact that side necking near a crack tip indicates the loss of stress triaxiality, which can be scaled by Q. From the out-of-plane displacement and the in-plane strain measured on the surface of side necking near the crack tip, stress field averaged through thickness is calculated and then Q is determined from the difference between the stress filed and the HRR field corresponding to the identical J-integral. To prove the validity, three-dimensional finite element simulation has been performed for a CT configuration with side-grooves. Q-value which was calculated directly from the near-tip stress field is compared with that determined by simulating the experimental procedure according to the proposed method, that is, the Q-value determined from the lateral displacement and the in-plane strain. Also, the effect of location where the displacement and strain are measured is explored. Moreover, an easy way for measuring the displacement and strain simultaneously is described. That is based on Stereoscopic Digital Photography and high resolution Digital Image Correlation (DIC) software, and can be performed along with conventional fracture tests. A case study for a CT specimen of ferritic steel is presented.
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Blouin, Arnaud, Stéphane Marie i Al Mahdi Remmal. "ATLAS+ European Project: Prediction of Large Ductile Tearing in Piping Using Local Approach". W ASME 2019 Pressure Vessels & Piping Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/pvp2019-93586.
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Abstract In the frame of the European ATLAS+ project it was decided to evaluate if a continuum damage model can simulate a four-points beading test on a ferritic pipe (A508 type). In this paper, the theoretical background is presented. Then, based on finite elements analyses, the GTN model damage parameters are defined by simulating laboratory tests on Notched Tensile specimens and Compact Tension specimens. From that identification, experimental tests on Single Edge Notched Tensile specimens are simulated in order to verify if the previous parameters are able to describe a large ductile tearing. Finally, the four points bending test simulation is also presented.
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Huemmer, Matthias, Elisabeth Keim i Harald Hoffmann. "TIMES: An International Project on Transferability of Fracture Toughness Values for Irradiated RPV Steels". W ASME 2007 Pressure Vessels and Piping Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/pvp2007-26125.
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The prediction of specimen or component failure behavior can be attained by the use of local approach (LA) models based on Weibull stresses. Over the last years recent developments have been achieved, and the predictive capabilities of these models have been improved significantly. In this paper a concept, which is based on a LA model, will be proposed for the prediction of fracture toughness for different specimen types made of ferritic base and weld metal in the unirradiated as well as in the irradiated state. The only necessary input parameter will be the yield strength of the material at one temperature (preferably room temperature). The LA model under consideration is tuned for its temperature dependence using a ferritic base material in the unirradiated material state. The outcome of the tuning are the Weibull parameters m, • •u, • •th, • •p,0. The parameters m, • •th, • •p,0 are kept constant over temperature and for variation of materials and fluences. To model the temperature dependence over the transition region, local events like plastic shielding, blunting or arrest of micro cracks have to be considered. These events are modeled via an increase of • •u over temperature. The temperature shift, • •T, in • •u, is obtained by using a correlation between the yield strength of the tuned material and the material under investigation. In order to validate this concept, a large number of computations, which includes different temperatures, specimen types, loading ratios, weld and base metal in unirradiated and irradiated conditions are conducted. They lead to the prediction of a median fracture toughness curve for each material and specimen type. All numerical investigations are compared with experimental results. It could be shown that the predictions made by this approach are in good agreement with the experiments. This is encouraging for further application to other materials and irradiation conditions.
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Waldbillig, D., Z. Tang, A. Burgess i O. Kesler. "Effect of Substrate and Cathode Parameters on the Properties of Suspension Plasma Sprayed Solid Oxide Fuel Cell Electrolytes". W ITSC2008, redaktorzy B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima i G. Montavon. Verlag für Schweißen und verwandte Verfahren DVS-Verlag GmbH, 2008. http://dx.doi.org/10.31399/asm.cp.itsc2008p0189.
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Abstract An axial injection suspension plasma spray system has been used to produce layers of fully stabilized yttria-stabilized zirconia (YSZ) that could be used as solid oxide fuel cell (SOFC) electrolytes. Suspension plasma spraying is a promising technique for the rapid production of coatings with fine microstructures and controlled porosity without requiring a post-deposition heat treatment. This new manufacturing technique to produce SOFC active layers requires the build up of a number of different plasma sprayed SOFC functional layers (cathode, electrolyte and anode) sequentially on top of each other. To understand the influence of the substrate and previously-deposited coating layers on subsequent coating layer properties, YSZ layers were deposited on top of plasma sprayed composite lanthanum strontium manganite (LSM)/YSZ cathode layers that were first deposited on porous ferritic stainless steel substrates. Three layer half cells consisting of the porous steel substrate, composite cathode, and suspension plasma sprayed electrolyte layer were then characterized. A systematic study was performed in order to investigate the effect of parameters such as substrate and cathode layer roughness, substrate surface pore size, and cathode microstructure and thickness on electrolyte deposition efficiency, cathode and electrolyte permeability, and layer microstructure.
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Madi, Yazid, Jacques Besson, Gre´goire Martin, Patrick Hornet i Mustafa Koc¸ak. "Fracture Behaviour of Mis-Matched Dissimilar Welds: Numerical Simulation Using Local Approach". W ASME 2002 Pressure Vessels and Piping Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/pvp2002-1100.
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The safety assessment of welded structures still remains an important industrial problem. In this study, a simple diffusion bonded bi-material jonction has been made in order to analyse the mismatch effect. It consists of an assembly of ferritic and austenitic steels which are representative of nuclear pressure vessel. Each material has been tested using smooth and notched tensile bars. These tests were used to adjust the parameters of local approach based on the Rousselier model. Bi-material structures including notch tensile bars, Charpy specimens and single-edge notch bend specimens were tested and simulated using the Finite Element method. The correct test/computation agreement shows that the adjusted parameters on the homogeneous specimens can be transferred to heterogeneous structures.
Raporty organizacyjne na temat "Ferric Order Parameters"
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Lahav, Ori, Albert Heber i David Broday. Elimination of emissions of ammonia and hydrogen sulfide from confined animal and feeding operations (CAFO) using an adsorption/liquid-redox process with biological regeneration. United States Department of Agriculture, marzec 2008. http://dx.doi.org/10.32747/2008.7695589.bard.
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The project was originally aimed at investigating and developing new efficient methods for cost effective removal of ammonia (NH₃) and hydrogen sulfide (H₂S) from Concentrated Animal Feeding Operations (CAFO), in particular broiler and laying houses (NH₃) and hog houses (H₂S). In both cases, the principal idea was to design and operate a dedicated air collection system that would be used for the treatment of the gases, and that would work independently from the general ventilation system. The advantages envisaged: (1) if collected at a point close to the source of generation, pollutants would arrive at the treatment system at higher concentrations; (2) the air in the vicinity of the animals would be cleaner, a fact that would promote animal growth rates; and (3) collection efficiency would be improved and adverse environmental impact reduced. For practical reasons, the project was divided in two: one effort concentrated on NH₃₍g₎ removal from chicken houses and another on H₂S₍g₎ removal from hog houses. NH₃₍g₎ removal: a novel approach was developed to reduce ammonia emissions from CAFOs in general, and poultry houses in particular. Air sucked by the dedicated air capturing system from close to the litter was shown to have NH₃₍g₎ concentrations an order of magnitude higher than at the vents of the ventilation system. The NH₃₍g₎ rich waste air was conveyed to an acidic (0<pH<~5) bubble column reactor where NH₃ was converted to NH₄⁺. The reactor operated in batch mode, starting at pH 0 and was switched to a new acidic absorption solution just before NH₃₍g₎ breakthrough occurred, at pH ~5. Experiments with a wide range of NH₃₍g₎ concentrations showed that the absorption efficiency was practically 100% throughout the process as long as the face velocity was below 4 cm/s. The potential advantages of the method include high absorption efficiency, lower NH₃₍g₎ concentrations in the vicinity of the birds, generation of a valuable product and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. H₂S₍g₎ removal: The main goal of this part was to develop a specific treatment process for minimizing H₂S₍g₎ emissions from hog houses. The proposed process consists of three units: In the 1ˢᵗ H₂S₍g₎ is absorbed into an acidic (pH<2) ferric iron solution and oxidized by Fe(III) to S⁰ in a bubble column reactor. In parallel, Fe(III) is reduced to Fe(II). In the 2ⁿᵈ unit Fe(II) is bio-oxidized back to Fe(III) by Acidithiobacillus ferrooxidans (AF).In the 3ʳᵈ unit S⁰ is separated from solution in a gravity settler. The work focused on three sub-processes: the kinetics of H₂S absorption into a ferric solution at low pH, the kinetics of Fe²⁺ oxidation by AF and the factors that affect ferric iron precipitation (a main obstacle for a continuous operation of the process) under the operational conditions. H₂S removal efficiency was found higher at a higher Fe(III) concentration and also higher for higher H₂S₍g₎ concentrations and lower flow rates of the treated air. The rate limiting step of the H₂S reactive absorption was found to be the chemical reaction rather than the transition from gas to liquid phase. H₂S₍g₎ removal efficiency of >95% was recorded with Fe(III) concentration of 9 g/L using typical AFO air compositions. The 2ⁿᵈ part of the work focused on kinetics of Fe(II) oxidation by AF. A new lab technique was developed for determining the kinetic equation and kinetic parameters (KS, Kₚ and mₘₐₓ) for the bacteria. The 3ʳᵈ part focused on iron oxide precipitation under the operational conditions. It was found that at lower pH (1.5) jarosite accumulation is slower and that the performance of the AF at this pH was sufficient for successive operation of the proposed process at the H₂S fluxes predicted from AFOs. A laboratory-scale test was carried out at Purdue University on the use of the integrated system for simultaneous hydrogen sulfide removal from a H₂S bubble column filled with ferric sulfate solution and biological regeneration of ferric ions in a packed column immobilized with enriched AFbacteria. Results demonstrated the technical feasibility of the integrated system for H₂S removal and simultaneous biological regeneration of Fe(III) for potential continuous treatment of H₂S released from CAFO. NH₃ and H₂S gradient measurements at egg layer and swine barns were conducted in winter and summer at Purdue. Results showed high potential to concentrate NH₃ and H₂S in hog buildings, and NH₃ in layer houses. H₂S emissions from layer houses were too low for a significant gradient. An NH₃ capturing system was designed and tested in a 100-chicken broiler room. Five bell-type collecting devices were installed over the litter to collect NH₃ emissions. While the air extraction system moved only 10% of the total room ventilation airflow rate, the fraction of total ammonia removed was 18%, because of the higher concentration air taken from near the litter. The system demonstrated the potential to reduce emissions from broiler facilities and to concentrate the NH₃ effluent for use in an emission control system. In summary, the project laid a solid foundation for the implementation of both processes, and also resulted in a significant scientific contribution related to AF kinetic studies and ferrous analytical measurements.