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Time-resolved, defect-hosted, trace element mobility in deformedWitwatersrand pyrite

Geoscience Frontiers 2019年第1期10卷 55-63页

作者： Denis Fougerouse steven m.reddy Christopher L.Kirkland David W.Saxey William D.Rickard Robert m.Hough School of Earth and Planetary Sciences The Institute for Geoscience Research (TIGeR) Curtin University Geoscience Atom Probe Advanced Resource Characterisation Facility John de Laeter Centre Curtin University CSIRO minerals Resources

The Pb isotopic composition of rocks is widely used to constrain the sources and mobility of melts and hydrothermal fluids in the Earth's crust. In many cases, the Pb isotopic composition appears to represent mixing of multiple Pb reservoirs. However, the nature, scale and mechanisms responsible for isotopic mixing are not well known. Additionally, the trace element composition of sulphide minerals are routinely used in ore deposit research, mineral exploration and environmental studies, though little is known about element mobility in sulphides during metamorphism and deformation. To investigate the mechanisms of trace element mobility in a deformed Witwatersrand pyrite(FeS_2), we have combined electron backscatter diffraction(EBSD) and atom probe microscopy(APm). The results indicate that the pyrite microstructural features record widely different Pb isotopic compositions, covering the entire range of previously published sulphide Pb compositions from the Witwatersrand basin. We show that entangled dislocations record enhanced Pb, Sb, Ni, Tl and Cu composition likely due to entrapment and short-circuit diffusion in dislocation cores. These dislocations preserve the Pb isotopic composition of the pyrite at the time of growth(~3 Ga) and show that dislocation intersections, likely to be common in deforming minerals, limit trace element mobility. In contrast, Pb, As, Ni, Co, Sb and Bi decorate a highangle grain boundary which formed soon after crystallisation by sub-grain rotation *** isotopic composition within this boundary indicates the addition of externally-derived Pb and trace elements during greenschist metamorphism at ~2 Ga. Our results show that discrete Pb reservoirs are nanometric in scale, and illustrate that grain boundaries may remain open systems for trace element mobility over 1 billion years after their formation.

关键词： Atom probe microscopy Nanoscale Nanogeochronology microstructure Isotope geochemistry Common Pb

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Bayesian geological and geophysical data fusion for the construction and uncertainty quantification of 3D geological models

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Geoscience Frontiers 2021年第1期12卷 479-493页

作者： Hugo K.H.Olierook Richard Scalzo David Kohn Rohitash Chandra Ehsan Farahbakhsh Chris Clark steven m.reddy R.Dietmar müller School of Earth and Planetary Sciences Curtin UniversityGPO Box U1987PerthWA6845Australia Centre for Translational Data Science University of SydneyNSW2006SydneyAustralia Sydney Informatics Hub University of SydneyNSW2006SydneyAustralia EarthByte Group School of GeosciencesUniversity of SydneyNSW2006SydneyAustralia Timescales of mineral Systems and John de Laeter Centre Curtin UniversityGPO Box U1987PerthWA6845Australia School of mathematics and Statistics University of New South WalesSydneyNSW2052Australia Department of mining Engineering Amirkabir University of Technology(Tehran Polytechnic)TehranIran

Traditional approaches to develop 3D geological models employ a mix of quantitative and qualitative scientific techniques,which do not fully provide quantification of uncertainty in the constructed models and fail to optimally weight geological field observations against constraints from geophysical ***,using the Bayesian Obsidian software package,we develop a methodology to fuse lithostratigraphic field observations with aeromagnetic and gravity data to build a 3D model in a small(13.5 km×13.5 km)region of the Gascoyne Province,Western *** approach is validated by comparing 3D model results to independently-constrained geological maps and cross-sections produced by the Geological Survey of Western *** fusing geological field data with aeromagnetic and gravity surveys,we show that 89%of the modelled region has>95%certainty for a particular geological unit for the given model and *** boundaries between geological units are characterized by narrow regions withm wide at the Earth's surface and 500-2000 m wide at ***~4 km depth,the model requires geophysical survey data with longer wavelengths(e.g.,active seismic)to constrain the deeper *** Obsidian was originally built for sedimentary basin problems,there is reasonable applicability to deformed terranes such as the Gascoyne ***,modification of the Bayesian engine to incorporate structural data will aid in developing more robust 3D ***,our results show that surface geological observations fused with geophysical survey data can yield reasonable 3D geological models with narrow uncertainty regions at the surface and shallow subsurface,which will be especially valuable for mineral exploration and the development of 3D geological models under cover.

关键词： Capricorn orogen machine learning Bayesian inference markov chain monte Carlo Solid earth mineral exploration

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黄铁矿显微结构对五龙金矿热液演化和成矿机制的制约

黄铁矿显微结构对五龙金矿热液演化和成矿机制的制约

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2020年中国地球科学联合学术年会

作者：谭伟 steven m.reddy DENIS FOUGEROUSE 王焰何宏平中国科学院广州地球化学研究所 Curtin University

石英脉型金矿的矿化过程本质上受到成矿流体物理化学性质的控制。多数热液成矿系统具有多期流体侵入的特征并伴随着多期矿化和矿物演化。黄铁矿在热液矿床中普遍存在,黄铁矿的难熔性是记录多期流体演化的有效证据。本文主要通过研究黄... 详细信息

石英脉型金矿的矿化过程本质上受到成矿流体物理化学性质的控制。多数热液成矿系统具有多期流体侵入的特征并伴随着多期矿化和矿物演化。黄铁矿在热液矿床中普遍存在,黄铁矿的难熔性是记录多期流体演化的有效证据。本文主要通过研究黄铁矿的显微结构特征(如位错、低角和高角边界等)(reddy and Hough, 2013),为厘清热液体系中的矿化事件提供线索。

关键词：黄铁矿五龙金矿成矿机制显微结构

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Entropy optimization on Casson nanofluid flow with radiation and Arrhenius activation energy over different geometries:A numerical and statistical approach

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Propulsion and Power Research 2024年第3期13卷 375-393页

作者： m.Priya P.Bala Anki reddy Department of mathematics S.A.S.Vellore Institute of TechnologyVellore 632014India

This study employs numerical and statistical approaches to investigate the entropy optimization of steady Casson nanofluidflow over three different geometries subject to boundary conditions induced by *** linear regression is employed to statistically *** present model incorporates several novel elements,such as Arrhenius activation energy,Brownian motion,the Cattaneo-Christov dualflux,thermophoresis,thermal radiation,and so ***,a comparison is presented between Newtonian and *** applying the proper similarity transformations,ordinary differential equations(ODEs)are ob-tained by converting foundational partial differential equations(PDEs).The Runge-Kutta fourth-order method is utilised to solve the obtained ODEs along with the shooting *** out-comes are visually depicted via tables and *** velocity drops with increasing Grashof number,and the magneticfield becomes progressively more forceful as the suction parameter *** temperature gets reduced with the increase of the suction parameter,solute Grashof number increases with the magneticfield,thermophoresis,and radiation *** entropy is observed to rise with the increase of the effective parameters(magneticfield,Brinkmann num-ber and radiation).The mAD(mean absolute deviation),mSE(mean squared error),and RmSE(root mean square error)values are approaching zero,indicating that the derived outcomes are highly accurate.A lower mAPE(mean absolute percentage error)suggests that the model has a higher level of ***,the outcomes of the present model are more precise and *** study has various potential applications such as power plant heat exchangers,material processing industries,and solar thermal energy systems.

关键词： Cassonfluid Arrhenius activation energy Entropy generation Thermophoresis multiple linear regression

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Enhanced saturation magnetization in La^(3+) doped NiCo ferrites prepared by sol-gel auto-combustion method

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Journal of Rare Earths 2024年第8期42卷 1546-1554,I0005页

作者： maddileti Jelli Vidyasagar Thopudurthy Krishna reddy C.V. Department of Physics Rayalaseema UniversityKurnoolA.P518007.Iindia Department of Physics Government PolytechnicRayachotiA.P516269India

Lanthanum doped nickel-cobalt nano ferrites with chemical formula Ni_(0.5)Co_(0.5)LaxFe_(2-x)O_(4)(x=0.05,0,10,0.15 and 0,20) were prepared using a simple sol-gel auto combustion *** basic structural properties were determined by X-ray diffraction method and the formation of single phased spinel ferrite was *** crystalline size decreased from 25 to 11 nm and lattice parameter a increases with increase of La *** surface morphology of these ferrites was observed by field-emission scanning electron microscopy(FESEm) and agglomerated irregular grains are observed with increase of the rare earth element La ***-dispersive X-ray spectroscopy(EDX) result confirms the presence of the required *** Fourier transform infrared spectroscopy(FTIR) spectrum indicates the formation of the spinel ferrite structure with m-O *** direct band measurements from ultraviolet-visible spectroscopy(UV-Vis) spectroscopy indicate that the direct band gap decreases from 1.39 to 1.19 eV for x=0.05 to x=0.15,then increases to 1.28 eV for x=*** room temperature magnetic properties of these ferrites were studied by a vibrating sample magnetometer(VSm).The enhanced saturation magnetization of 49.73 emu/g is observed for x=0.10 and then saturation magnetizations are gradually decreased for x=0.15 and x=*** the remanent magnetization and coercivity also follow the same trend.

关键词： Ferrites Sol-gel auto combustion La doping magnetic properties Rare earths

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Oxygen uptake response to switching stairs exercise by non-parametric modeling

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Control Theory and Technology 2024年第2期22卷 315-325页

作者： Hairong Yu Chenyu Zhang Kai Cao Hamzah m.Alqudah steven Weidong Su Key Laboratory of Child Development and Learning Science of ministry of Education and the School of Biological Science and medical Engineering Southeast UniversityNanjing210096JiangsuChina College of Artificial Intelligence and Big Data for medical Science Shandong First Medical University and Shandong Academy of Medical SciencesJinan250117ShandongChina Faculty of Engineering and Information Technology University of Technology SydneyUltimoNSW2007Australia

Oxygen uptake plays a crucial role in the evaluation of endurance performance during exercise and is extensively utilized for metabolic assessment. This study records the oxygen uptake during the exercise phase (i.e., ascending or descending) of the stair exercise, utilizing an experimental dataset that includes ten participants and covers various exercise periods. Based on the designed experiment protocol, a non-parametric modeling method with kernel-based regularization is generally applied to estimate the oxygen uptake changes during the switching stairs exercise, which closely resembles daily life activities. The modeling results indicate the effectiveness of the non-parametric modeling approach when compared to fixed-order models in terms of accuracy, stability, and compatibility. The influence of exercise duration on estimated fitness reveals that the model of the phase-oxygen uptake system is not time-invariant related to respiratory metabolism regulation and muscle fatigue. Consequently, it allows us to study the humans’ conversion mechanism at different metabolic rates and facilitates the standardization and development of exercise prescriptions.

关键词： Non-parametric modeling Interval stair training exercise Kernel method.Cardiorespiratory response Oxygen uptake

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Thermodynamic analysis of metal segregation in dual phase high entropy ceramics

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Journal of materiomics 2024年第4期10卷 889-895页

作者： steven m.Smith II William G.Fahrenholtz Gregory E.Hilmas Stefano Curtarolo missouri University of Science and Technology Materials Science and Engineering DepartmentRollaMO65409USA Duke University Department of Mechanical Engineering and Materials ScienceDurhamNC27708USA Duke University Center of Autonomous Materials DesignDurhamNC27708USA

Equilibrium Gibbs'free energy calculations were used to determine metal segregation trends between boride and carbide solid solutions containing two metals that are relevant to dual phase high entropy *** model predicted that Ti had the strongest tendency to segregate to the boride phase followed by Zr,Nb,mo,V,Hf,and Ta,which matches experimental results of measured *** ratio of a metal in the carbide phase to the content of the same metal in the corresponding metal boride had a linear trend with the change in standard Gibbs'free energy of reaction for a metal carbide reacting with B_(4)C to produce its corresponding metal boride and *** proposed model was used to predict the changes in standard Gibbs'free energy for CrC→CrB_(2) to be−260 kJ and WC→WB_(2) to be 148 kJ,which indicates that Cr has the strongest segregation to the boride and W has the strongest segregation to the *** proposed model can be used to estimate the segregation of metals in dual phase high entropy boride-carbide ceramics of any boride/carbide ratio or metal content.

关键词： Dual phase High entropy ceramic Boride Carbide Thermodynamics

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Secure and efficient prediction of electric vehicle charging demand usingα^(2)-LSTm and AES-128 cryptography

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Energy and AI 2024年第2期16卷 84-100页

作者： manish Bharat Ritesh Dash K.Jyotheeswara reddy A.S.R.murty Dhanamjayulu C. S.m.muyeen Department of Electrical and Electronics Engineering Visvesvaraya Technological UniversityBelgaumIndia School of Electrical and Electronics Engineering REVA UniversityBangaloreIndia School of Electrical Engineering Vellore Institute of TechnologyVelloreIndia Department of Electrical Engineering Qatar UniversityDoha2713Qatar

In recent years,there has been a significant surge in demand for electric vehicles(EVs),necessitating accurate prediction of EV charging *** prediction plays a crucial role in evaluating its impact on the power grid,encompassing power management and peak demand *** this paper,a novel deep neural network based onα^(2)-LSTm is proposed to predict the demand for charging from electric vehicles at a 15-minute time ***,we employ AES-128 for station quantization and secure communication with *** proposed algorithm achieves a 9.2%reduction in both the Root mean Square Error(RmSE)and the mean absolute error compared to LSTm,along with a 13.01%increase in demand *** present a 12-month prediction of EV charging demand at charging stations,accompanied by an effective comparative analysis of mean Absolute Percentage Error(mAPE)and mean Percentage Error(mPE)over the last five years using our proposed *** prediction analysis has been conducted using Python programming.

关键词： Charging demand forecasting Deep neural network Electric vehicles LSTm Peak demand management

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Rare earth metal doped CeO_2-based catalytic materials for diesel soot oxidation at lower temperatures

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Journal of Rare Earths 2015年第11期33卷 1162-1169页

作者： A.Rangaswamy Putla Sudarsanam Benjaram m.reddy Inorganic and Physical Chemistry Division CSIR-Indian Institute of Chemical Technology Centre for Advanced materials and Industrial Chemistry (CAmIC) School of Applied Sciences RMIT University

In this work, the influence of trivalent rare-earth dopants（Sm and La） on the structure-activity properties of CeO2 was thoroughly studied for diesel soot oxidation. For this, an optimized 40% of Sm and La was incorporated into the CeO2 using a facile coprecipitation method from ultra-high dilute aqueous solutions. A systematic physicochemical characterization was carried out using X-ray diffraction（XRD）, transmission electron microscopy（TEm）, Brumauer-Emmett-teller method（BET） surface area, X-ray photoelectron spectroscopy（XPS）, Raman, and H2-temperature programmed reduction（TPR） techniques. The soot oxidation efficiency of the catalysts was investigated using a thermogravimetric method. The XRD results suggested the formation of nanocrystalline single phase CeO2-Sm2O3 and CeO2-La2O3 solid solutions. The Sm- and La-doped CeO2 materials exhibited smaller crystallite size and higher BET surface area compared with the pure CeO2. Owing to the difference in the oxidation states of the dopants（Sm3＋ and La3＋） and the Ce4＋, a number of oxygen vacancies were generated in CeO2-Sm2O3 and CeO2-La2O3 samples. The H2-TPR studies evidenced the improved reducible nature of the CeO2-Sm2O3 and CeO2-La2O3 samples compared with the CeO2. It was found that the addition of Sm and La to the CeO2 outstandingly enhanced its catalytic efficiency for the oxidation of diesel soot. The observed 50% soot conversion temperatures for the CeO2-Sm2O3, CeO2-La2O3 and CeO2 were ~790, 843 and 864 K（loose contact）, respectively, and similar activity order was also found under the tight contact condition. The high soot oxidation efficacy of the CeO2-Sm2O3 sample was attributed to numerous catalytically favourable properties, like smaller crystallite size, larger surface area, abundant oxygen vacancies, and superior reducible nature.

关键词： rare earths cerium oxide solid solutions oxygen vacancies soot oxidation

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High-temperature elemental segregation induced structure degradation in high-entropy fluorite oxide

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Journal of Advanced Ceramics 2024年第3期13卷 310-322页

作者： Yixuan Hu mariappan Anandkumar Yumeng Zhang Joydip Joardar Atul Suresh Deshpande Xiaodong Wang Kolan madhav reddy School of materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of materials Science and metallurgical Engineering Indian Institute of Technology HyderabadSangareddy 502285India International Advanced Research Centre for Powder metallurgy and New materials(ARCI) Hyderabad 500005India

Fluorite-structured oxides constitute an important category of oxides with a wide range of high-temperature *** the concept of high entropy,high-entropy fluorite oxides(HEFOs)have showcased intriguing high-temperature application ***,unlocking this potential necessitates an assessment of their long-term stability under high-temperature *** this study,we conducted a prolonged heat treatment at 1000℃on typical HEFO,specifically(CeHfZrGdLa)O_(x).After 100 h,high-intensity X-ray diffraction(XRD)revealed a transition from a single-phase fluorite to a multi-phase *** investigation by analytical electron microscoy(AEm)demonstrated that this degradation resulted from facilitated element diffusion and consequent escalating chemical fluctuation at high temperatures,leading to spontaneous segregation and separation of Ce and La elements,forming Ce-rich,La-poor,and La-rich ***,the La-rich phase spontaneously transformed from a fluorite structure(space group Fm3m)to a bixbyite structure(space group Ia3)at elevated temperatures,resulting in the appearance of superstructure reflection in XRD profiles and electron diffraction *** the intricate phase decomposition,the energy band gap showed minimal variation,suggesting potential property stability of(CeHfZrGdLa)O_(x)across a broad range of *** findings offer valuable insights into the future applications of HEFOs.

关键词： phase transition high-temperature stability elemental segregation high-entropy fluorite oxides(HEFOs)

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