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Numerical analysis of the effects of vesicle distribution characteristics on the engineering properties of volcanic rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2023年第12期15卷 3094-3104页

作者： P.L.P.Wasantha Z.Heng t.xu College of Sport Health and EngineeringVictoria UniversityMelbourneVIC3011Australia Institute for Sustainable Industries and Liveable Cities Victoria UniversityMelbourneVIC3011Australia Center for Rock Instability and Seismicity Research Northeastern UniversityShenyang110819China

Vesicles can be of different sizes and shapes and can be randomly distributed within vesicular volcanic rocks. this study investigates the variation of engineering properties of vesicular rocks due to the changes in vesicle distribution characteristics for different cases of bulk porosity and vesicle diameter using a systematic numerical simulation program using the finite element method-based rock failure process analysis (RFPA) software. Models with uniform-size vesicles and combinations of different proportions of different-sized vesicles were considered to resemble natural vesicular rocks more closely, and ten different random vesicle distributions were tested for each case. Increasing bulk porosity decreased the uniaxial compressive strength (UCS) and elastic modulus of the specimens, and the specimens with the lowest bulk porosity showed the greatest range of UCS values in the case of uniform-size vesicles. the effect of vesicle diameter on UCS showed an unsystematic response which was understood to be a result of different vesicle distribution patterns, some of which facilitated a shear failure. Specimens with multiple-size vesicles in different proportions revealed that the variation of UCS due to vesicle distribution characteristics is minimum when the bulk porosity is equally shared by different size vesicles. In addition, when the proportion of smaller-sized vesicles is higher, UCS showed an increase compared to that of the equal proportion of different size vesicles case at low porosities, but a decrease at higher porosities. Variation of elastic modulus showed minor, unsystematic fluctuations as a function of vesicle diameter and different proportions of different-sized vesicles, and the range for different vesicle distribution patterns was narrow in general. Overall, the findings of this study recommend cautious use of the engineering properties determined through a limited number of laboratory tests on vesicular rocks.

关键词： Vesicular rocks Porosity Vesicle size and distribution Numerical simulation Mechanical characteristics

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HIGH-CURRENt PULSED ELECtRON BEAM: RAPID SURFACE ALLOYING AND WEAR RESIStANCE IMPROVEMENt

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Acta Metallurgica Sinica(English Letters) 2003年第4期16卷 276-282页

作者： J.xu H.W.Liu Z.R.Zhou C.Dong A.M.Wu S.Z.Hao A.M.Zhang t.xu tribologyResearchInstitute SouthwestJiaotongUniversityChengdu610031ChinaManuscriptreceived25November2002 StateKeyLab.forMaterialsModificationbyLaser IonandElectronBeamsDalianUniversityofTech-nologyDalian116024China StateKeyLaboratoryofSolidLubrication LanzhouInstituteofChemicalPhysicsTheChineseAcademyofSciencesLanzhou730000China

the present paper reports the rapid surface alloying induced by the bombardment of high-current pulsed electron beam. two kinds of substrate materials were examined to show this effect. the first sample was a pure Al metal pre-coated with fine carbon powders prior to the bombardment, and the second alloy is the D2-Crl2MolVl mould steel pre-coated with Cr, ti, and tiN powders. the surface elements diffuse about several micrometers into the substrate materials only after several bombardments. tribological behaviors of these samples were characterized and significant improvement in wear resistance was found. Finally, a tEM analysis reveals the presence of stress waves generated by coupled thermal and stress fields, which was considered as the main cause of the enhanced properties.

关键词： high-current pulsed electron beam surface alloying tribology fretting wear

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Solid-state alloying of Al-Mg alloys by accumulative roll-bonding:Microstructure and properties

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Journal of Materials Science & technology 2022年第30期125卷 238-251页

作者： X.M.Mei Q.S.Mei J.Y.Li C.L.Li L.Wan F.Chen Z.H.Chen t.xu Y.C.Wang Y.Y.tan School of Power and Mechanical Engineering Wuhan UniversityWuhan 430072China Key Laboratory of Hydraulic Machinery transients(Wuhan University) Ministry of EducationWuhan 430072China School of Mechanical Engineering Wuhan Polytechnic UniversityWuhan 430023China

In this study,a novel solid-state alloying approach was adopted to fabricate Al-Mg alloys with high Mg contents(C_(Mg)) by accumulative roll-bonding(ARB)of Al and Mg elemental materials to ultrahigh *** results showed that the degree of alloying increased with the increase of ARB cycles and a supersaturatedα-Al solid solution accompanied with nanoprecipitates was formed in the Al-Mg alloys by ARB to 70 *** as-prepared Al-Mg alloys exhibited enhanced mechanical properties,with a maximum tensile strength of∼615 MPa and a tensile elongation of∼10%at C_(Mg)=13 wt.%.the high strength can be attributed to different mechanisms,namely solid solution strengthening,grain boundary strengthening,dislocation strengthening,and precipitation *** Al-Mg alloys showed increased work hardening with increasing C_(Mg),due to the enhanced formation of ***,no obvious drop in the intergranular corrosion(IGC)resistance was found in the Al-Mg alloys with C_(Mg) up to 13 wt.%.Moreover,sensitization treatment was found to induce little decrease in the IGC resistance of the Al-Mg alloys with C_(Mg)≤13 wt.%.We found that the excellent IGC resistance was due to the suppression of grain boundary precipitation by the preferred formation of precipitates within the grains that were induced by *** study indicated the novelty of the present solid-state alloying approach to achieving a superior combination of high mechanical properties and IGC resistance in Al-Mg alloys.

关键词： Solid-state alloying Al-Mg alloys Mechanical properties IGC resistance ARB

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浙江花岗岩的工程岩石学研究(英文)

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地质与资源 2005年第3期14卷 176-180页

作者： Moustafa El Omella1 C.A.tang t.xu 东北大学岩石破裂诱发地震研究中心

对浙江省花岗岩的岩相学特征及力学性质进行了研究以确定它们之间的关系.矿物学研究显示出花岗岩的交代蚀变特征,这可以反映在岩石的力学性质上.岩石材料的物理性质决定其工程学性质,在相关定量参数确定的情况下,可以预测岩石材料的工... 详细信息

对浙江省花岗岩的岩相学特征及力学性质进行了研究以确定它们之间的关系.矿物学研究显示出花岗岩的交代蚀变特征,这可以反映在岩石的力学性质上.岩石材料的物理性质决定其工程学性质,在相关定量参数确定的情况下,可以预测岩石材料的工程学性质.镜下观察、硬度、密度、孔隙度及点负荷强度均可作为所研究花岗岩的定量参数.上述每个因素都可提供岩石工程学的可靠预测.岩石的物理性质受岩石成分及蚀变状态控制,而岩石的工程学性质和力学特征是其物理性质的函数.

关键词：花岗岩工程岩石学岩相学蚀变矿物浙江省

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Studies of laser-plasma interaction physics with low-density targets for direct-drive inertial confinement fusion on the Shenguang III prototype

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Matter and Radiation at Extremes 2021年第2期6卷 54-66页

作者： V.t.tikhonchuk t.Gong N.Jourdain O.Renner F.P.Condamine K.Q.Pan W.Nazarov L.Hudec J.Limpouch R.Liska M.Krus F.Wang D.Yang S.W.Li Z.C.Li Z.Y.Guan Y.G.Liu t.xu X.S.Peng X.M.Liu Y.L.Li J.Li t.M.Song J.M.Yang S.E.Jiang B.H.Zhang W.Y.Huo G.Ren Y.H.Chen W.Zheng Y.K.Ding K.Lan S.Weber ELI-Beamlines Institute of PhysicsCzech Academy of Sciences25241 Dolni BrezanyCzech Republic Centre Lasers Intenses et Applications University of Bordeaux-CNRS-CEA33405 TalenceFrance Laser Fusion Research Center China Academy of Engineering PhysicsMianyang 621900China Institute of Plasma Physics Czech Academy of Sciences18200 PragueCzech Republic Independent Foam target Supplier CarnoustieDD76DPUnited Kingdom Faculty of Nuclear Sciences and Physical Engineering Czech Technical University in Prague11519 PragueCzech Republic Institute of Applied Physics and Computational Mathematics Beijing 100088China Center for Applied Physics and technology Peking UniversityBeijing 100871China School of Science Xi’an Jiaotong UniversityXi’an 710049China

the physics of laser-plasma interaction is studied on the Shenguang III prototype laser facility under conditions relevant to inertial confinement fusion designs.A sub-millimeter-size underdense hot plasma is created by ionization of a low-density plastic foam by four high-energy(3.2 kJ)laser *** interaction beam is fired with a delay permitting evaluation of the excitation of parametric instabilities at different stages of plasma *** diagnostics are used for plasma characterization,scattered radiation,and accelerated *** experimental results are analyzed with radiation hydrodynamic simulations that take account of foam ionization and *** measured level of stimulated Raman scattering is almost one order of magnitude larger than that measured in experiments with gasbags and hohlraums on the same installation,possibly because of a greater plasma *** amplification is achieved in high-intensity speckles,indicating the importance of implementing laser temporal smoothing techniques with a large bandwidth for controlling laser propagation and absorption.

关键词： density. interaction scattered

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Design,simulation,and testing of a tunable MEMS multi-threshold inertial switch

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Microsystems & Nanoengineering 2024年第2期10卷 37-46页

作者： Qiu xu Rodrigo t.Rocha Yousef Algoos Eric Feron Mohammad I.Younis Faculty of Electronic Information Engineering Huaiyin Institute of TechnologyHuai’an223003PR China Computer Electrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal23955-6900Saudi Arabia Piezoelectric Microsystem technologies Silicon Austria LabsVillach9524Austria Physical Sciences and Engineering Division King Abdullah University of Science and TechnologyThuwal23955Saudi Arabia Mechanical Engineering Department State University of New YorkBinghamtonNY13902USA

this paper presents a tunable multi-threshold micro-electromechanical inertial switch with adjustable threshold *** demonstrated device combines the advantages of accelerometers in providing quantitative acceleration measurements and g-threshold switches in saving power when in the inactive state upon experiencing acceleration below the *** designed proof-of-concept device with two thresholds consists of a cantilever microbeam and two stationary electrodes placed at different positions in the sensing *** adjustable threshold capability and the effect of the shock duration on the threshold acceleration are analytically investigated using a nonlinear beam *** are shown for the relationships among the applied bias voltage,the duration of shock impact,and the tunable *** fabricated prototypes are tested using a shock-table *** analytical results agree with the experimental *** designed device concept is very promising for the classification of the shock and impact loads in transportation and healthcare applications.

关键词： tunable acceleration testing

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Life under tension: the relevance of force on biological polymers

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Biophysics Reports 2024年第1期10卷 48-56页

作者： Matthew t.J.Halma Longfu xu Department of Physics and Astronomy and Laser Lab Vrije Universiteit Amsterdam LUMICKS B.V.

Optical tweezers have elucidated numerous biological processes, particularly by enabling the precise manipulation and measurement of tension. One question concerns the biological relevance of these experiments and the generalizability of these experiments to wider biological systems. Here, we categorize the applicability of the information garnered from optical tweezers in two distinct categories: the direct relevance of tension in biological systems, and what experiments under tension can tell us about biological systems, while these systems do not reach the same tension as the experiment, still, these artificial experimental systems reveal insights into the operations of biological machines and life processes.

关键词： tension Optical tweezers Molecular force

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CdS/LaFeO_(3) heterojunctions with improved optical properties for visible-light catalytic applications

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Journal of Rare Earths 2024年第5期42卷 879-888,I0003页

作者： Jiaqi Wei Wen Zhu xuelian xu Xiao xu Junjiang Zhu Hubei Key Laboratory of Biomass Fibers and Eco-dyeing&Finishing College of Chemistry and Chemical EngineeringWuhan Textile University ChemistryWuhan430200China

Construction of heterojunctions is a normal and effective strategy to improve the photocatalytic performances of semiconductors,through which both the lifetime and the redox ability of electrons/holes can be improved,as co mpared to the respective *** this basis,we constructed Z-scheme CdS/LaFeO_(3) heterojunctions(CdS/LFO),by in-situ growing different amounts of CdS on the surface of LaFeO_(3),for photocatalytic degradation of tetracycline hydrochloride(tC)in aqueous solution at room *** crystal structure,surface morphology and optoelectronic properties of the COS/LFO heterojunctions were systemically characterized to correlate the reaction *** tests indicate that the CdS/LFO heterojunctions exhibit promising activity for tC degradation under visible light irradiation(λ≥420 nm),with 85%tC conversion obtained at reaction time of 45 min,which is 3.4 and 1.9 times higher than that of CdS and LaFeO_(3).the CdS/LFO heterojunctions are also stable in the reaction and can be reused for four cycles with no appreciable activity *** applicability of CdS/LFO to photocatalytic degradation of organic dyes,as well as the reaction mechanism,was also explored.

关键词： LaFeO_(3) CdS Photocatalytic degradation tetracycline hydrochloride Reaction mechanism Rare earths

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Solubility determination and comparison ofβ-HMX and RDX in two binary mixed solvents(acetonitrile+water,nitric acid+water)

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Chinese Journal of Chemical Engineering 2024年第5期69卷 238-249页

作者： Yuehua Yao Fan Wang Yinguang xu Zishuai xu Lizhen Chen Jianlong Wang School of Chemistry and Chemical Engineering North University of ChinaTaiyuan 030051China Gansu Yinguang Chemical Industry Group Co.Ltd. Baiyin 730900China

In order to remove hexahydro-1,3,5-trinitro-1,3,5-triazine(RDX),the main impurity,in process of polymorphic transformation of octrahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine(HMX),the solubility ofβ-HMX and RDX in acetonitrile(ACN)+water in the temperature range of 288.15-333.15 K and in nitric acid(HNO_(3))+water in the temperature range of 298.15-333.15 K were measured by laser dynamic *** results showed that the solubility of bothβ-HMX and RDX in binary mixed solvents increased monotonously as the temperature increase at a given solvent composition or with increasing of mole fraction of solvent(ACN and nitric acid).Solubility data were well correlated by the modified Apelblat equation,Jouyban-Acree model,Yaws equation and van't Hoff equation,and the Yaws equation achieved the best fitting results according to the relative error and the mean square error ***,the solubility ofβ-HMX and RDX in binary mixed solvent was compared,based on the solubility difference and the solvent's own properties,the best separation degree ofβ-HMX and RDX was found when the mole fraction of nitric acid was 0.22 at room temperature,which provided data support for HMX crystallization in mixed *** solubility differences between RDX andβ-HMX in mixed solvents were explained from the formation of intermolecular and intramolecular hydrogen bonds.

关键词： Solubility Octrahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine Hexahydro-1,3,5-trinitro-1,3,5-triazine Separation Model Hydrogen bond

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Evaluation on Configuration Stiffness of Overconstrained 2R1t Parallel Mechanisms

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 62-82页

作者： xuejian Ma Zhenghe xu Yundou xu Yu Wang Jiantao Yao Yongsheng Zhao Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan UniversityQinhuangdao 066004China Key Laboratory of Advanced Forging and Stamping technology and Science of Ministry of National Education Yanshan UniversityQinhuangdao 066004China

Currently,two rotations and one translation(2R1t)three-degree-of-freedom(DOF)parallel mechanisms(PMs)are widely applied in five-DOF hybrid machining ***,there is a lack of an effective method to evaluate the configuration stiffness of mechanisms during the mechanism design *** is a challenge to select appropriate 2R1t PMs with excellent stiffness performance during the design *** the operational status of 2R1t PMs,the bending and torsional stiffness are considered as indices to evaluate PMs'configuration ***,a specific method is proposed to calculate these stiffness ***,the various types of structural and driving stiffness for each branch are assessed and their specific values ***,a rigid-flexible coupled force model for the over-constrained 2R1t PM is established,and the proposed evaluation method is used to analyze the configuration stiffness of the five 2R1t PMs in the entire ***,the driving force and constraint force of each branch in the whole working space are calculated to further elucidate the stiffness evaluating results by using the proposed method *** obtained results demonstrate that the bending and torsional stiffness of the 2RPU/UPR/RPR mechanism along the x and y-directions are larger than the other four mechanisms.

关键词： Parallel mechanism Stiffness Over-constrained three degrees of freedom

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