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Influence of Ti^(4+) doping on hyperfine field parameters of Mg_(0.95)Mn_(0.05)Fe_(2-2x)Ti_(2x)O_4(0≤x≤0.7)

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journal of Central South University 2010年第6期17卷 1139-1143页

作者： KUMAR S PRAKASH R ALIMUDDIN CHOI H K KOO B H SONg j I CHUNg H jEONg H lee C g School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and BK21 Eco-Friendly Heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The mixed spinel ferrite system Mg0.95Mn0.05Fe2-2xTizxO4 （0 ≤x ≤ 0.7） was synthesized by the conventional solid-state reaction technique. The effect of Ti^4＋ doping was studied by using the Moessbauer spectroscopy measurements at room temperature. From the analysis of the Moessbauer spectra, it is observed that s-electron density, electric field gradient （EFg）, quadrupole coupling constant （QCC） and the net hyperfine magnetic fields acting on the Moessbauer nuclei-FeA^3＋ and FeB^3＋ change with the increase of Ti^4＋ doping in Mg0.95Mn0.05Fe2O4. The hyperfine magnetic field decreases with the increase of Ti^4＋ doping.

关键词： spinel ferrite Moessbauer spectroscopy hyperfine magnetic field isomer shift Ti^4+ doping

Mssbauer spectra of MnFe_(2-2x)Al_(2x)O_4(0≤x≤0.4) ferrites

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journal of Central South University 2010年第6期17卷 1129-1132页

作者： BATOO K M KUMAR S PRAKASH R ALIMUDDIN SONg j I CHUNg H jEONg H KOO B H lee C g King Abdullah Institute for Nanotechnology King Saud UniversityRiyadh 11451Saudi Arabia School of Nano and Advanced Materials Engineering Changwon National UniversityChangwon 641773Korea Department of Mechanical Engineering Changwon National UniversityChangwon 641773Korea Department of Applied Physics Aligarh Muslim UniversityAligarh 202002India Department of Precision & Mechanical Engineering and BK21 Eco-Friendly Heat & Cooling Energy Mechanical Research Team Gyeongsang National U niversityTongyeong 650160Korea

The effect of non-magnetic Al^3＋ ion doping on the magnetic properties of MnFe2-2x Al2xO4 （0 ≤x≤ 0.4） spinel ferrites was studied using Moessbauer spectroscopy measurements at room temperature. From the Moessbauer study, it is observed that the ：esolved hyperfine sextets are due to the distribution of Fe ions on the two sublattices of the spinel ferrites. The value of the isomer shift obtained from the fitting of the Moessbauer spectra indicates that Fe ions are in ＋3 state. A paramagnetic doublet is observed at ：iegree of inversion x=0.4, superimposed on the hyperfine sextets, indicating that the super-exchange interaction A-B decreases due to ：he dilution of sublattice by Al^3＋ ions. The hyperfine magnetic field decreases at both interstitial sites of tetrahedral （A） and 3ctahedral （B） with the increase in Al concentration.

关键词： ferrites hyperfine interactions Moessbauer spectroscopy isomer shift

Fault detection method with PCA and LDA and its application to induction motor

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journal of Central South University 2010年第6期17卷 1238-1242页

作者： jUNg D Y lee S M 王洪梅 KIM j H lee S H Daeho Tech Company Limited Department of Electronics Engineering Inha University School of Mechatronics Changwon National University

A feature extraction and fusion algorithm was constructed by combining principal component analysis(PCA) and linear discriminant analysis(LDA) to detect a fault state of the induction *** yielding a feature vector with PCA and LDA from current signal that was measured by an experiment,the reference data were used to produce matching *** a diagnostic step,two matching values that were obtained by PCA and LDA,respectively,were combined by probability model,and a faulted signal was finally *** the proposed diagnosis algorithm brings only merits of PCA and LDA into relief,it shows excellent performance under the noisy *** simulation was executed under various noisy conditions in order to demonstrate the suitability of the proposed algorithm and showed more excellent performance than the case just using conventional PCA or LDA.

关键词： principal component analysis (PCA) linear discriminant analysis (LDA) induction motor fault diagnosis fusionalgorithm

Rapid climate change-induced collapse of hunter-gatherer societies in the lower Mississippi River valley between ca. 3300 and 2780 cal yr BP

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Science China Earth Sciences 2018年第2期61卷 178-189页

作者： tristram r.kidder edward r.henry lee j.arco Department of Anthropology Washington University in St. Louis St. Louis 63130 USA geoarehaeology Laboratory Washington University in St. Louis St. Louis 63130 USA gAI Consultants Inc. Homestead PA 15120 USA Teaching and Experimental Center for Archaeology and Cultural Heritage Protection Henan University Kaifeng 475001 China

Hunter-gatherer communities in the American Southeast reached an apogee of social and political complexity in the period between ca. 4200 and 3000 cal yr BP. In the lower Mississippi Valley(LMV) the Poverty Point culture defined this period of socio-political elaboration. However, following a significant period of climate change that led to exceptional flooding and a major reorganization of the course of the Mississippi River, this culture collapsed beginning ca. 3300–3200 cal yr BP and the LMV was abandoned for the subsequent 500 years. In this study, we use data from the jaketown site in the Yazoo Basin of west-central Mississippi to refine the chronology of the climate event that caused the collapse of the Poverty Point culture. A large flood buried Poverty Point-era occupation deposits at jaketown around 3310 cal yr BP. Lateral migration of the Mississippi River during flooding led to inundation of the Yazoo Basin and re-occupation of ancient river courses. A coarse sand stratum topped by a more than a meter-thick fining upward sediment package marks a crevasse deposit caused by a rupture of the natural levee at jaketown. This levee breach was part of a larger pattern of erratic flooding throughout the LMV and is associated with major landscape evolution and the abandonment of Poverty Point sites within the valley. Early Woodland peoples re-colonized the crevasse surface after ca. 2780 cal yr BP. Following this event, the jaketown site and the eastern Yazoo Basin witnessed a period of landscape stability that lasts to this day. These archaeological data demonstrate how climate change and natural disasters can lead to socio-political dissolution and reorganization even in relatively small-scale hunter-gatherer populations.

关键词： Rapid climate change Hunter-gatherers Flooding Mississippi River Valley Poverty Point jaketown site

Boosting the oxygen evolution reaction performance of wrinkled Mn(OH)_(2) via conductive activation with a carbon binder

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journal of Energy Chemistry 2022年第8期31卷 580-587,I0016页

作者： Kahyun Ham jaewon lee Kiyoung lee jaeyoung lee School of Earth Sciences and Environmental Engineering Gwangju Institute of Science and Technology(GIST)123 Cheomdangwagi-RoGwangju 61005South Korea International Future Research Center of Chemical Energy Storage and Conversion Processes GIST123 Cheomdangwagi-RoGwangju 61005South Korea Ertl Center for Electrochemical and Catalysis GIST123 Cheomdangwagi-RoGwangju 61005South Korea Department of Chemistry and Chemical Engineering Inha University100 Inha-RoIncheon 22212South Korea

Electrochemical water splitting is one of the most reliable approaches for environmental-friendly hydrogen *** of their stability and abundance,Mn-based materials have been studied as electrocatalysts for the oxygen evolution reaction(OER),which is a more sluggish reaction in the water splitting *** increase the OER activity of Mn,it is imperative to facilitate the structural change of Mn oxide to the active phase with Mn_(3)+species,known as the active ***,we present the relationship between the electronic conductivity in the catalyst layer and the formation of the Mn active phase,δ-MnO_(2),from wrinkled Mn(OH)_(2).Mn(OH)_(2) has poor conductivity,and it disrupts the oxidation reaction toward MnOOH orδ-MnO_(2).Adjacent conductive carbon to Mn(OH)_(2) enabled Mn(OH)_(2) to be oxidized toδ-MnO_(2).Furthermore,after repetitive cyclic voltammetry activation,the more conductive environment resulted in a higher density ofδ-MnO_(2) through the irreversible phase transition,and thus it contributes to the improvement of the OER activity.

关键词： Hydrogen production Oxygen evolution reaction Anion exchange membrane water electrolysis Anodization Manganese oxide

DISSOLUTION KINETICS OF PHOSPHATE ORE IN ACIDIC SOLUTIONS

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Chinese journal of Chemical Engineering 1994年第2期2卷 13-22页

作者：马三剑 E.T.M.j.Martynowicz g.j.Witkamp g.M.vanRosmalen Faculty of Chemical Technology and Material Science Delft University of TechnologyLeeghwaterstraat 442628RZ DelftThe Netherlands

The dissolution kinetics of Florida and jordan phosphate ore was studied in diluted nitric acid (0.2, 0.5, 1.0 mol ·L-1), and in phosphoric acid (55 wt% H3PO4) aqueous solutions. It was found that the hydrogen ions concentration is a controlling factor, but the calcium ions concentration can not affect the dissolution rate in the range of 0.0 and 2.0 wt% Ca2+. The effects of temperature, stirring intensity and the size of ore particles were also investigated. The transfer of hydrogen ion depends on the diffusion, while the calcium ions transfer is assumed to be depended on mechanically stripping. The shrinking core model with hydrogen ions diffusion control match the experimental results.

关键词： dissolution kinetics phosphate ore diffusion mechanically stripping hydrogen calcium ions concentration shrinking core model

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： H.T.jeong S.W.lee W.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the HCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation grain size grain growth

Investigation on 3Dt wake flow structures of swimming bionic fish

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Acta Mechanica Sinica 2012年第5期28卷 1494-1508页

作者： g.-X.Shen g.-K.Tan g.-j.Lai Fluid Mechanics Institute Beihang University

A bionic experimental platform was designed for the purpose of investigating time accurate three-dimensional flow field, using digital particle image velocimetry （DSPIV）. The wake behind the flapping trail of a robotic fish model was studied at high spatial resolution. The study was performed in a water channel. A robot fish model was designed and built. The model was fixed onto a rigid support frame- work using a cable-supporting method, with twelve stretched wires. The entire tail of the model can perform prescribed motions in two degrees of freedom, mainly in carangiform mode, by driving its afterbody and lunate caudal fin respectively. The DSPIV system was set up to operate in a trans- lational manner, measuring velocity field in a series of parallel slices. Phase locked measurements were repeated for a number of runs, allowing reconstruction of phase average flow field. Vortex structures with phase history of the wake were obtained. The study reveals some new and complex three-dimensional flow structures in the wake of the fish, including ＂reverse hairpin vortex＂ and ＂reverse Karman S-H vortex rings＂, allowing insight into physics of this complex flow.

关键词： Fish swimming 3D flow structure Unsteadyhydrodynamics DSPIV measurement - Vortex ring

Evaluation of fatty acid metabolism and innate immunity interactions between commercial broiler, F1 layer × broiler cross and commercial layer strains selected for different growth potentials

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journal of Animal Science and Biotechnology 2018年第1期9卷 156-166页

作者： Nicky-lee Willson Rebecca E.A.Forder Rick g.Tearle greg S.Nattrass Robert j.Hughes Philip I.Hynd School of Animal and Veterinary Sciences The University of Adelaide The Australian Poultry and Cooperative Research Centre University of New England Davies Research Centre School of Animal and Veterinary SciencesThe University of Adelaide South Australian Research and Development Institute(SARDI) Livestock and Farming Systems South Australian Research and Development Institute(SARDI) Pig and Poultry Production Institute

Background： The broiler industry has undergone intense genetic selection over the past 50 yr. resulting in improvements for growth and feed efficiency, however, significant variation remains for performance and growth traits. Production improvements have been coupled with unfavourable metabolic consequences, including immunological trade-offs for growth, and excess fat deposition. To determine whether interactions between fatty acid（FA） metabolism and innate immunity may be associated with performance variations commonly seen within commercial broiler flocks, total carcass lipid %, carcass and blood FA composition, as wel as genes involved with FA metabolism, immunity and cel ular stress were investigated in male birds of a broiler strain, layer strain and F1 layer × broiler cross at d 14 post hatch. Heterophil：lymphocyte ratios, relative organ weights and bodyweight data were also ***： Broiler bodyweight（n = 12） was four times that of layers（n = 12） by d 14 and had significantly higher carcass fat percentage compared to the cross（n = 6; P = 0.002） and layers（P = 0.017） which were not significantly different from each other（P = 0.523）. The carcass and whole blood FA analysis revealed differences in the FA composition between the three groups indicating altered FA metabolism, despite al being raised on the same diet. genes associated with FA synthesis andβ-oxidation were upregulated in the broilers compared to the layers indicating a net overal increase in FA metabolism,which may be driven by the larger relative liver size as a percentage of bodyweight in the broilers. genes involved in innate immunity such as TLR2 and TLR4, as wel as organel e stress indicators ERN1 and XBP1 were found to be nonsignificant, with the exception of high expression levels of XBP1 in layers compared to the cross and broilers. Additional y there was no difference in heterophil： lymphocytes between any of the ***： The results provide evidence that genetic selecti

关键词： Broiler Cel ular stress Fatty acid metabolism Innate immunity Layer Selection