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Application of response surface methodology(RSM) for optimization of leaching parameters for ash reduction from low-grade coal

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International Journal of Mining Science and Technology 2018年第4期28卷 617-625页

作者： Sushanta Kumar behera Himanshu Meena Sudipto chakraborty b.c.Meikap Department of chemical Engineering Indian Institute of Technology (IIT) Kharagpur Department of chemical Engineering School of Engineering Howard College University of Kwazulu-Natal (UKZN)

coal is the world＇s most abundant energy source because of its abundance and relatively low cost. Due to the scarcity in the supply of high-grade coal, it is necessary to use low-.grade coal for fulfilling energy demands of modern civilization. However, due to ItS high ash and moisture content, low-grade coal exerts the substantial impact on their consumption like pyrolysis, liquefaction, gasification and combus- tion process. The present research aimed to develop the efficient technique for the production of clean coal by optimizing the operating parameters with the help of response surface methodology. The effect of three independent variables such as hydrofluoric acid （HF） concentration （10-20% by vo!ume ）,. temper- ature （60-100 ~c）, and time （90-180 min）, for ash reduction from the low-grade coal was Investigated.. A quadratic model was proposed to correlate the independent variables for maximum ash reduction at the optimum process condition by using central composite design （cc.D）method. The study reveals that HF concentration was the most effective parameter for ash reduction in comparison with time and temper- ature. It may be due to the higher F-statistics value for HF concentration, which effects to large extent of ash reduction. The characterization of coal was evaluated by Fourier transform infrared spectroscopy （FTIR） analysis and Field-emission scanning electron microscopy with energy-dispersive X-ray （FESEM- EDX） analysis for confirmation of the ash reduction.

关键词： Low-grade coal Hydrofluoric acid (HF)Leaching Ash reduction Response surface methodology

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Spectroscopic and fluorescence properties of Sm^(3+)-doped zincfluorophosphate glasses

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Journal of Rare Earths 2014年第10期32卷 918-926页

作者： V.b.Sreedhar ch.basavapoornima c.K.Jayasankar Department of Physics Sri Venkateswara University Department of Physics National Degree and P.G. College

Optical absorption and fluorescence spectra of Sm3＋-doped zincfluorophosphate glasses with molar composition of 44P2O5＋17K20＋9Al2O3＋（30-χ）ZnF2＋χSm2O3 （χ=0.01 mol.%, 0.05 mol.%, 0.1 mol.%, 0.5 mol.%, 1.0 mol.%, 2.0 and 3.0 mol.%） referred as PKAZFSm were prepared by melt quenching technique and were characterized through Raman, absorption, emission and decay curve analysis. From the absorption spectra, Judd-Ofelt intensity parameters were determined and were used to predict radiative properties such as transition probabilities （AR, radiative lifetimes （τR）, branching ratios （βR）, effective bandwidths （△λeff） and stimulated emission cross-section （σ（λp）） for the excited 4G5/2 luminescent level. The decay curve for the 4G5/2 level was single exponential for lower concentration and became non-exponential for higher concentrations. The non-exponential nature of the decay curves of the 4G5/2 level increased with increase in Sm3＋ ions concentration accompanied by decrease in lifetime due to energy transfer processes among the Sm3＋ ions. The non-exponential decay curves was well fitted to the generalized Inokuti-Hirayama model for S=6, indicating that the energy transfer among optically active ions was of dipole-dipole interaction. The cross-relaxation mechanism responsible for the quenching of lifetimes and the effect of variation of concentration on the spectroscopic properties were also discussed.

关键词： zincfluorophosphate glasses samarium Raman spectrum optical properties fluorescence properties rare earths

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Flash X-ray radiography technique to study the high velocity impact of soft projectile on E-glass/epoxy composite material

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Defence Technology（防务技术） 2019年第2期15卷 216-226页

作者： b.Venkata Ramudu c.Jayarami Reddy V.Madhu Armour Design and Development Division Defence Metallurgical Research Laboratory

In the present paper, the high velocity impact of 9 mm soft lead projectile on 10 mm and 30 mm thick Eglass/epoxy composites was studied using a 450 kV Flash X-ray radiography(FXR) system. The basic parameters of FXR imaging, such as effect of ratio of target to film(TF) and source to target(ST) distances and X-ray penetration thickness of the composite material were optimized based on clarity and the actual dimensions of the objects. The optimized parameters were used in the FXR imaging of the ballistic event of 9 mm soft projectile on E-glass/epoxy composite. The real time deformation patterns of both the projectile and composite target during the ballistic impact were captured and studied at different time intervals. The notable failure modes of the 10 mm thick target with time include fibre breakage, bulging on the back side, delamination, recovery of the bulging, reverse bulging and its recovery. However, with increase in thickness of the target to 30 mm the only failure mechanism observed is the breaking of fibres. The ballistic impact event was also numerically simulated using commercially available LS-DYNA software. The numerically simulated deformation patterns of the projectile and target at different time intervals are closely matching with the corresponding radiographic images.

关键词： Flash X-ray radiography E-Glass/epoxy composite ballistic impact Numerical simulation

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combustion synthesis, characterization and luminescence properties of barium aluminate phosphor

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Journal of Rare Earths 2014年第9期32卷 806-811页

作者： A.H. Wako F.b Dejene H.c Swart Department of Physics University of the Free State (Qwaqwa Campus) Department of Physics University of the Free State

The blue-green emitting Eu2＋ and Nd3＋ doped polycrystalline barium aluminate （baAI204：Eu2＋,Nd3＋） phosphor, was prepared by a solution-combustion method at 500 ℃without a post-annealing process. The characteristic variation in the structural and luminescence properties of the as-prepared samples was evaluated with regards to a change in the ba/A1 molar ratio from 0.1：1 to 1.4：1. The morphologies and the phase structures of the products were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）, while the optical properties were investigated using ultra-violet （UV） and photoluminescence （PL） spectroscopy, respectively. The XRD and TEM results revealed that the average crystallite size of the baAl2O4：Eu2＋,Nd3＋ phosphor was about 70 urn. The broad-band UV-excited luminescence of the phosphors was observed at 2max=500 um due to transitions from the 4f^65d1 to the 4f7 configuration of the Eu2＋ ion. The PL results indicated that the main peaks in the emission and excitation spectrum of phosphor particles slightly shifted to the short wavelength due to the changes in the crystal field due to the structure changes caused by the variation in the quantity of the ba ions in the host lattice.

关键词： baAl2O4:Eu2+,Nd3+ persistence luminescence Eu2+ and Nd3+ doping rare earths

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Enhanced visible-light photocatalytic activity of multi-elements-doped ZrO_2 for degradation of indigo carmine

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Journal of Rare Earths 2015年第5期33卷 498-506页

作者： E.S.Agorku A.T.Kuvarega b.b.Mamba A.c.Pandey A.K.Mishra Department of Applied chemistry University of Johannesburg University of South Africa College of Engineering Science and Technology Nanotechnology & Water Sustainability Research Unit Florida Campus Nanotechnology and Application centre University of Allahabad

In this study, c,N,S-doped ZrO2 and a series of Eu doped c,N,S-ZrO2 photocatalysts were synthesized by a coprecipitation method using thiourea as the source of c, N and S and Eu（NO3）·6H2O as source of Eu. The materials were characterized by X-ray dif-fraction （XRD）, Raman spectroscopy, Fourier transform infrared spectroscopy （FTIR）, UV-visible diffuse reflectance spectroscopy, scanning electron microscopy （SEM）/energy dispersive X-ray spectroscopy （EDX）, and transmission electron microscopy （TEM）. Indigo carmine （Ic） was chosen as a model for organic pollutants and used to evaluate the photocatalytic performance of the photo-catalysts under simulated solar light. commercial ZrO2 was used as a reference material. XRD and Raman results indicated the for-mation of both tetragonal and monoclinic phase ZrO2 with particle size ranging from 8–30 nm. Multi-element doping had a great in-fluence on the optical responses manifested as red shift in the absorption edge. The highest photocatalytic activity towards Ic was observed for the Eu,c,N,S-doped ZrO2 （0.6 mol.%Eu） sample （k=1.09×10–2 min–1）. The commercial ZrO2 showed the lowest photo-degradation activity （k=5.83×10–4 min–1）. The results showed that the control of Eu doping in the c,N,S-ZrO2 was very important in reducing electron-hole recombination. The synergistic effect of Eu, c, N, and S in the ZrO2 matrix led to enhanced utilization of simulated solar energy for the degradation of Ic through narrowing of bandgaps.

关键词： photocatalysis indigo carmine multi-elements-doped ZrO2 rare earths

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Polycyclic Aromatic Hydrocarbon Molecule-Surface binding Energies in Site Specific Graphene bilayer Nanopores: A Puzzle-ene Force Field calculation

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Graphene 2017年第3期6卷 72-84页

作者： Thomas R. Rybolt claire b. black Department of chemistry and Physics University of Tennessee at Chattanooga Chattanooga USA

Two-dimensional molecular recognition studies of the six polyaromatic hydro-carbons that can be formed from the combination of four benzene rings: tetracene, pyrene, 1,2-benzanthracene, 3,4-benzphenanthrene, triphenylene, and chrysene were explored for each of these six molecules interacting with six different graphene layer site-specific nanopores. computational studies were done for the gas phase adsorption on single layer graphene, bilayer graphene, and six molecule-specific graphene bilayer nanopores. Molecular mechanics MM2 parameters have been shown previously to provide good comparisons to experimental adsorption energies for aromatic hydrocarbons adsorption on graphitic surfaces. These binding energies are dominated by van der Waals forces. Just as a jigsaw puzzle hole can accommodate only a specific piece, two-dimensional shape specific sites were created in the top layer of a graphene bilayer to match each one of the six adsorbate molecules. The purpose of this study was to examine the molecular recognition possibilities of site specific adsorption in these simple two-dimensional nanopores based on dispersion forces and molecular shape. For example, triphenylene has a calculated surface binding energy of 24.5 kcal/mol on the graphene bilayer and 30.2 kcal/mol in its own site specific pore. The interaction energy of this molecule in the other five sites ranged from 17.6 to 23.8 kcal/mol. All the molecules tetracene, pyrene, 1,2-benzanthracene, triphenylene and chrysene had higher binding energies in their matched molecule bilayer sites than on either single or double layer graphene. In addition, each one of these five molecules had a stronger binding in their own shape specific (puzzle-ene) site than any of the other molecular sites. The results suggest that two-dimensional molecular recognition based on shape specific pores may allow selectivity useful for applications such as sensors, separations, nanofabrication, or information storage.

关键词： Molecule-Graphene Interaction Molecular Mechanics Adsorption Energy binding Energy on Graphene Polycyclic Aromatic Hydrocarbons Two-Dimensional Molecular Recognition

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In-situ gas contents of a multi-section coal seam in Sydney basin for coal and gas outburst management

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International Journal of coal Science & Technology 2023年第4期10卷 34-46页

作者： Zhongbei Li Ting Ren Dennis black Ming Qiao Itmam Abedin Jessica Juric Mike Wang School of civil MiningEnvironmental and Architectural EngineeringUniversity of WollongongWollongongNSW 2522Australia South32–Illawarra Metallurgical coal WollongongNSW 2526Australia School of Safety Engineering China University of Mining and TechnologyXuzhou 221116China

The gas content is crucial for evaluating coal and gas outburst potential in underground coal mining. This study focuses on investigating the in-situ coal seam gas content and gas sorption capacity in a representative coal seam with multiple sections (A1, A2, and A3) in the Sydney basin, where the cO_(2) composition exceeds 90%. The fast direct desorption method and associated devices were described in detail and employed to measure the in-situ gas components (Q_(1), Q_(2), and Q_(3)) of the coal seam. The results show that in-situ total gas content (Q_(T)) ranges from 9.48 m^(3)/t for the A2 section to 14.80 m^(3)/t for the A3 section, surpassing the Level 2 outburst threshold limit value, thereby necessitating gas drainage measures. Among the gas components, Q_(2) demonstrates the highest contribution to Q_(T), ranging between 55% and 70%. Furthermore, high-pressure isothermal gas sorption experiments were conducted on coal samples from each seam section to explore their gas sorption capacity. The Langmuir model accurately characterizes cO_(2) sorption behavior, with ft coefcients (R^(2)) greater than 0.99. Strong positive correlations are observed between in-situ gas content and Langmuir volume, as well as between residual gas content (Q_(3)) and sorption hysteresis. Notably, the A3 seam section is proved to have a higher outburst propensity due to its higher Q_(1) and Q_(2) gas contents, lower sorption hysteresis, and reduced coal toughness f value. The insights derived from the study can contribute to the development of efective gas management strategies and enhance the safety and efciency of coal mining operations.

关键词： In-situ coal seam gas content Direct desorption method Gas component Sorption capacity coal and gas outburst

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Delayed Ionization and Delayed Detachment in Molecules and clusters

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chinese Journal of chemical Physics 2009年第2期22卷 162-170页

作者： F. Lépine b. baguenard b. concina M. A. Lebeault c. bordas Université de Lyon F-69522 Lyon France Université Lyon 1 Villeurbanne cNRS UMR 5579 LASIM

The evolution of a molecular system excited above its ionization threshold depends on a number of parameters that include the nature of the excited states and their couplings to the various continua. The general nature of the processes governing this evolution depends also essentially on the complexity of the molecule, more precisely on its size, density of states, and strength of the couplings among the various internal degrees of freedom. In this paper we address the question of the transition between autoionization that prevails in small molecules, and delayed ionization occurring in larger molecules or clusters. This transition is illustrated by autoionization of Na2 Rydberg states on one hand, delayed ionization in fullerene c60, and delayed detachment in small cluster anions on the other hand. All processes are studied in the case of nanosecond laser excitation, corresponding to a rather slow deposition of the internal energy.

关键词： Autoionization Autodetachment Thermionic emission

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Semi-analytical investigation of heat transfer in a porous convective radiative moving longitudinal fin exposed to magnetic field in the presence of a shape-dependent trihybrid nanofluid

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 197-216页

作者： c.G.PAVITHRA b.J.GIREESHA M.L.KEERTHI Department of PG Studies and Research in Mathematics Kuvempu UniversityShankaraghatta 577451India Department of Mathematics and Statistics M.S.Ramaiah University of Applied SciencesBengaluru 560058India

The thermal examination of a non-integer-ordered mobile fin with a magnetism in the presence of a trihybrid nanofluid(Fe_3O_4-Au-Zn-blood) is carried out. Three types of nanoparticles, each having a different shape, are considered. These shapes include spherical(Fe_3O_4), cylindrical(Au), and platelet(Zn) configurations. The combination approach is utilized to evaluate the physical and thermal characteristics of the trihybrid and hybrid nanofluids, excluding the thermal conductivity and dynamic viscosity. These two properties are inferred by means of the interpolation method based on the volume fraction of nanoparticles. The governing equation is transformed into a dimensionless form, and the Adomian decomposition Sumudu transform method(ADSTM) is adopted to solve the conundrum of a moving fin immersed in a trihybrid nanofluid. The obtained results agree well with those numerical simulation results, indicating that this research is reliable. The influence of diverse factors on the thermal overview for varying noninteger values of γ is analyzed and presented in graphical representations. Furthermore, the fluctuations in the heat transfer concerning the pertinent parameters are studied. The results show that the heat flux in the presence of the combination of spherical, cylindrical, and platelet nanoparticles is higher than that in the presence of the combination of only spherical and cylindrical nanoparticles. The temperature at the fin tip increases by 0.705 759% when the value of the Peclet number increases by 400%, while decreases by 11.825 13% when the value of the Hartman number increases by 400%.

关键词： convection radiation moving longitudinal fin Adomian decomposition Sumudu transform method(ADSTM) trihybrid nanofluid magnetic field

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Variations in zonal fruit starch concentrations of apples – a developmental phenomenon or an indication of ripening?

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Horticulture Research 2015年第1期2卷 84-92页

作者： Franziska c Doerflinger William b Miller Jacqueline F Nock christopher b Watkins Horticulture Section School of Integrative Plant ScienceCornell UniversityIthaca14853NYUSA School of Agriculture Food&WineUniversity of AdelaideWaite CampusGlen Osmond5064South AustraliaAustralia

Patterns of starch hydrolysis in stem,equatorial,and calyx zones of‘Honeycrisp’and‘Empire’apples(Malus sylvestris(L.)Mill ***(borkh.)Mansf.)during maturation and ripening,and in‘Gala’apples in response to propylene or 1-methylcyclopropene(1-McP)treatments after harvest,were *** in zonal starch concentrations were found for‘Empire’and‘Gala’fruits,but not for‘Honeycrisp’.During maturation and ripening of‘Empire’,the concentration of starch was highest in the calyx end and lowest in the stem region.Differences in rates of starch hydrolysis among zones were not detected.‘Honeycrisp’and‘Empire’had the highest concentration of sorbitol in the calyx region,whereas it was highest in the stem-end region in‘Gala’.The distribution differences of glucose,fructose,and sucrose were similar in all three cultivars;higher fructose and glucose concentrations in the stem region,and higher sucrose concentrations in the calyx end of the *** treatment of‘Gala’with propylene did not affect the internal ethylene concentration of the fruit but 1-McP markedly inhibited *** concentrations were highest in the calyx end but gradients of starch among zones were not changed by postharvest *** rate of hydrolysis was slowed by 1-McP treatment,but was unaffected by *** treatments influenced sorbitol,glucose,and fructose *** of starch concentration among the zones did not confirm differences in ripening,but reflected its uneven distribution throughout the fruit during ***,measured differences in zonal starch are most likely related to starch accumulation during fruit development,rather than differences in rates of starch degradation during ripening.

关键词： cultivar fir starch

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