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A hybrid multi-degree-of-freedom vibration isolation platform for spacecrafts by the linear active disturbance rejection control

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Applied Mathematics and Mechanics(English Edition) 2020年第5期41卷 805-818页

作者： Weichao CHI s.j.MA j.Q.sUN College of science Northeastern UniversityShenyang 100819China Key Laboratory of Ministry of Education on safe Mining of Deep Metal Mines Northeastern UniversityShenyang 100819China Department of Mechanical Engineering School of EngineeringUniversity of CaliforniaMercedCA 95343U.S.A.

The hybrid vibration isolation, which takes advantages of both the passive and active approaches, has been an important solution for space missions. The objective of this paper is to design a vibration isolation platform for payloads on spacecrafts with the robust, wide bandwidth, and multi-degree-of-freedom(MDOF). The proposed solution is based on a parallel mechanism with six voice-coil motors(VCMs) as the actuators. The linear active disturbance resistance control(LADRC) algorithm is used for the active control. Numerical simulation results show that the vibration isolation platform performs effectively over a wide bandwidth, and the resonance introduced by the passive isolation is eliminated. The system robustness to the uncertainties of the structure is also verified by simulation.

关键词： hybrid vibration isolation stewart platform linear active disturbance rejection control(LADRC) stability robustness

Plasma density measurement and downstream etching of silicon and silicon oxide in Ar/NF3 mixture remote plasma source

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Plasma science and Technology 2019年第6期21卷 52-57页

作者： H j YEOM D H CHOI Y s LEE j H KIM D j.s.ONG s j YOU H C LEE Korea Research Institute of standards and science(KRIss) Daejeon 34113 Republic of Korea Department of Physics Chungnam National University Daejeon 34134 Republic of Korea

In this study,plasma density measurements were performed near the plume region of the remote plasma source (RPs) in Ar/NF3 gas mixtures using a microwave cutoff *** measured plasma density is in the range of 1010-1011 cm-3 in the discharge conditions with RPs powers of 2-4 kW and gas pressures of 0.87-4 *** plasma density decreased with increasing gas pressures and RPs powers under various Ar/NF3 mixing *** decrease in the plasma density measured at the fixed measurement position (plume region) can be understood by the reduction of the electron energy relaxation length with increases in the gas pressures and mixing ratio of NF3/(Ar/NF3).We also performed downstream etching of silicon and silicon oxide films in this *** etch rate of the silicon films significantly increases while the silicon oxide is slightly etched with the gas pressures and *** was also found that the etch rate strongly depends on the wafer position on the processing chamber electrode,and that the etch selectivity reached 96-131 in the discharge conditions of RF powers (3730-4180 W) and gas pressures (3.6-4 Torr).

关键词： remote plasma source electron density cutoff probe downstream etch

Flow of colloidal suspension and irreversibility analysis with aggregation kinematics of nanoparticles in a microchannel

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Applied Mathematics and Mechanics(English Edition) 2020年第11期41卷 1671-1684页

作者： s.sINDHU B.j.GIREEsHA Department of studies and Research in Mathematics Kuvempu UniversityShankaraghattaShivamogga 577451KarnatakaIndia

The current exploration focuses on the ethylene glycol(EG)based nanoliquid flow in a *** effectiveness of the internal heat source and linear radiation is reflected in the present *** estimation of suitable thermal conductivity model has affirmative impact on the convective heat transfer *** examination is conceded with the nanoparticle aggregation demonstrated by the Maxwell-Bruggeman and Krieger-Dougherty models which tackle the formation of *** models effectively describe the thermal conductivity and viscosity *** dimensionless mathematical expressions are solved numerically by the Runge Kutta Fehlberg approach.A higher thermal field is attained for the Bruggeman model due to the formation of thermal bridge.A second law analysis is carried out to predict the sources of irreversibility associated with the thermal *** is remarked that lesser entropy generation is obtained for the aggregation *** entropy generation rate declines with the slip flow and the thermal heat flux.A notable enhancement in the Bejan number is attained by increasing the Biot *** is established that the nanoparticle aggragation model exhibits a higher Bejan number in comparision with the usual flow model.

关键词： nanoparticle aggregation nanoliquid microchannel slip parameter heat flux

Constraining the links between the Himalayan belt and the Central Myanmar Basins during the Cenozoic:An integrated multi-proxy detrital geochronology and trace-element geochemistry study

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Geoscience Frontiers 2021年第2期12卷 657-676页

作者： F.Arboit M.Min D.Chew A.Mitchell K.Drost E.Badenszki j.s.Daly Department of Geology Trinity College DublinDublinIreland Department of Geology University of MandalayMandalayMyanmar Myanmar Precious Resources Group and 20 Dale Close OxfordOX11TUUK UCD school of Earth sciences University College DublinDublinIreland iCRAG(Irish Centre for Research in Applied Geosciences) University College DublinDublinIreland Department of Earth science Khalifa UniversityAbu DhabiUnited Arab Emirates

Geological and tectonic analysis of the Eastern Himalayan basins has given rise to a decade-long debate on the geodynamic evolution of the Burmese terrane and on the extent of reorganization of the main sE Asia drainage ***,the influence of the Himalayan belt on the Central Myanmar Basin(CMB)system remains poorly documented,although it is key to providing more accurate models for the evolution of the Himalayan-Burmese *** this contribution,we present geochronological,isotopic and geochemical analysis from 2500 zircon,1700 titanite,700 rutile and 850 apatite detrital grains from fifteen Cenozoic siliciclastic samples and one Cretaceous igneous *** samples were collected within the fore-and back-arc basins of the Central Myanmar Basin domain(CMB)to constrain the provenance,maximum depositional ages,and depositional environments of the west Burma *** key lithological units,the sadwingyi,Ketpanda,Wabo Chaung,Gwegon,Minwun,Padaung,Okmintaung and Irrawaddy formations have detrital age spectra spanning from the Miocene to *** entire data set has common age peaks at ca.20,40,60,90,100 Ma,with about 80%of the U–Pb ages younger than ca.140 Ma and only ca.1%of the grains predating ca.3.0 *** results shed light on the current ambiguities on the transport pathways of Himalayan detritus in the *** show that the fore-arc basin was open to the trench and fed by the unroofing of both the Wuntho Popa volcanic arc to the east and possibly from the Burmese basement and/or from Himalayan-derived Bengal Fan detritus to the west during the Eocene,from at least ca.44 Ma to before ca.39 *** show that the west Burma Terrane was partitioned into pull-apart basins such as the Minwun Basin,which during the Oligocene recorded the first evidence of a new source contribution into the CMB at ca.27 *** new source is characterized by detritus highly compatible with the sE Asia basement rocks,which we suggest corresponds to the initiation of t

关键词： Geochronology Geochemistry Himalaya Indo Burma Range Myanmar Provenance

Forging strength-ductility unity in a high entropy steel

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journal of Materials science & Technology 2022年第18期113卷 158-165页

作者： s.j.Tsianikas Y.Chen j.jeong s.Zhang Z.Xie school of Mechanical Engineering The University of AdelaideSA 5005Australia Centre for Advanced Thin Film Materials and Devices Faculty of Materials and EnergySouthwest UniversityChongqing 400715China Max-Planck-Institut für Eisenforschung Max-Planck-Straße 1Düsseldorf 40237Germany

Fe_(72.4)Co_(13.9)Cr_(10.4)Mn_(2.7)B_(0.34)high entropy steel was prepared by magnetron *** alloy exhibits a high yield strength of 2.92±0.36 GPa while achieving appreciable plasticity of 13.7±1.9%at the ultimate compressive strength(3.37±0.36 GPa).The distribution of iron and chromium shows an un-usual,characteristic spinodal-like pattern at the nanometer scale,where compositions of Fe and Cr show strong anticorrelation and vary by as much as 20 at.%.The high strength is largely attributable to the compositional modulations,combined with fine grains with body-centered cubic(BCC)crystal structure,as well as grain boundary segregation of interstitial *** impressive plasticity is accommodated by the formation and operation of multiplanar,multicharacter dislocation slips,mediated by coherent in-terfaces,and controlled by shear *** excellent strength-ductility combination is thus enabled by a range of distinctive strengthening mechanisms,rendering the new alloy a potential candidate for safety-critical,load-bearing structural applications.

关键词： Deformation mechanisms Micromechanical testing Compositional fluctuations Body-centered cubic High entropy steel

Effects of some Thiol Chelators on Enzymatic Activities in Blood, Liver and Kidneys ofAcute Arsenic (Ⅲ) Exposed Mice

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Biomedical and Environmental sciences 1998年第1期11卷 38-45页

作者： NEELIMATRIPATHI s.j.s.LORA DivisionofPharmacologyandToxicology DefenceResearchandDevelopmentEstablishmentGwalior－474002India D

The effects of meso 2, 3-dimercaptosuccinic acid (DMsA), sodium 2, 3 dimercaptopropane 1-sulfonate (DMPs) and s-adenosyl L-methionine (sAM) on the enzymatic activities of mice were studied. The mice were given intraperitoneal (i. p. ) injections of these chelating agents (1 mmol/kg) and 3 h later the activity of 8-aminolevulinic acid dehydratase (ALAD) in the blood, and aspartate aminotransferase (AsT), alanine aminotransferase (ALT), γ-glutamyltranspeptidase (γ-GT), alkaline phosphatase (ALP) in the liver and kidney were determined. The activity of blood ALAD was significantly increased by the administration of DMsA and sAM while DMPs had only a moderate effect. The activities of other hepatic enzymes changed little when the mice were treated with these chelating agents, except for a significant reduction in hepatic ALP activlty following DMPs administration. Arsenic (Ⅲ) administration markedly increased the activities of ALT and ALP in the liver and kidneys. The changes in the enzymatic activities by treatment with arsenic were prevented by injection of DMsA,DMPs and sAM, DMsA being the most effective. These results indicate that DMsA, DMPs and sAM were not toxic to the liver or kidneys of mice and that treatment with DMsA is more effective than DMPs or sAM in protecting mice from acute hepatic or renal toxicity caused by arsenic.

关键词： DMsA Effects of some Thiol Chelators on Enzymatic Activities in Blood Exposed Mice Liver and Kidneys ofAcute Arsenic

spin synthesis of monolayer of siO_2 thin films

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journal of semiconductors 2015年第4期36卷 16-25页

作者： s.s.shinde s.Park j.s.in Korea Research Institute of standards and science

The highly ordered monolayer of submicron size silica （siO2） particles （235 nm） is developed on p-silicon by using three-step spin-coating in colloidal suspension, which has significant potential in various applications. The influence of three-step spin speeds, spinning time, acceleration time between different steps, concentration of siO2 particles in the solution, solution quantity, and the ambient humidity （relative humidity） on the properties ofmonolayer siO2 are studied in order to achieve a large area monolayer film. A relatively high surface coverage and uniform monolayer film of siO2 particles in the range of 85%-90% are achieved by appropriate control of the preparative parameters. We conclude that this method can be useful in industrial applications, because of the fabrication speed, surface coverage and cost of the process.

关键词： thin films spin synthesis electron microscopy

Metasomatic stages and scapolitization Effects on Chemical Composition of Pasveh Pluton,NW Iran

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journal of Earth science 2011年第5期22卷 619-631页

作者： s A Mazhari s Amini j Ghalamghash F Bea Department of Geology Payame Noor University Department of Geology Tarbiat Moallem University Geological survey of Iran Department of Mineralogy and Petrology Fuentenueva CampusUniversity of Granada

Pasveh gabbros are mafic component of a plutonic complex in the northwest sanandaj- sirjan Zone. These cumulative rocks are composed of plagioclase and calcic clinopyroxene （Cpx）, which yield unusually high CaO （〉19 wt.%） in whole-rock chemistry. Petrographical and geochemical data suggest that Pasveh gabbros can be divided into two groups： free scapolite and scapolite-bearing gabbros. The second group has higher Na20, K20, and P205 relative to free scapolite ones and is enriched in LIL （large ion lithophile） and HFs （high field strength） elements. Two stages of metasomatism affected the primary composition of mafic rocks. Firstly, high temperature reaction caused to invert primary high Ti clinopyroxene to low Ti cUnopyroxene＋high Ti amphibole. This reaction was extensive and included all gabbroic samples. Hydrothermal fluids involved in this process can be derived from dehydration reactions of country rocks or from other magmas incorporated in the formation of Pasveh complex pluton. The second metasomatic stage relates to scapolitization of limited parts of gabbroic rocks. An external saline fluid, which is composed of major NaCI and minor KCI and P205 components, impacted locally on Pasveh gabbros and formed the second metasomatic stage. Possible sources of Na and Cl are primary evaporites or brines, which were present in the host sediments of the gabbros. The carbonate-free nature of these hydrothermal fluids suggests that hydrothermal fluids responsible for the formation of scapolite in Pasveh gabbros are derived from marine evaporitic parentage.

关键词： Iran sanandaj.s.rjan Zone Pasveh pluton gabbro metasomatism high Ti Cpx low Ti Cpx amphibole scapolite.

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金属在脉冲载荷下的性态

金属在脉冲载荷下的性态