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Effect of dry-wet cycles on dynamic properties and microstructures of sandstone:Experiments and modelling

International Journal of Mining Science and Technology 2024年第5期34卷 655-679页

作者： Hai pu Qingyu Yi Andrey p.Jivkov Zhengfu Bian Weiqiang Chen Jiangyu Wu State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Earth Engineering China University of Mining and TechnologyXuzhou 221116China Key Laboratory of Xinjiang Coal Resources Green Mining Ministry of EducationXinjiang Institute of EngineeringUrumqi 830023China Department of Solids and Structures School of EngineeringUniversity of ManchesterManchester M139PLUK School of Environment Science and Spatial Informatics China University of Mining and TechnologyXuzhou 221116China Department of Civil and Environmental Engineering Rice UniversityHouston 77005USA State Key Laboratory of High performance Civil Engineering Materials Jiangsu Research Institute of Building Science Co.Ltd.Nanjing 210008China Department of Materials University of OxfordOxford OX13PHUK

Underground pumped storage power plant(UpSp)is an innovative concept for space recycling of abandoned *** realization requires better understanding of the dynamic performance and durability of reservoir *** paper conducted ultrasonic detection,split Hopkinson pressure bar(SHpB)impact,mercury intrusion porosimetry(MIp),and backscatter electron observation(BSE)tests to investigate the dynamical behaviour and microstructure of sandstone with cyclical dry-wet damage.A coupling FEM-DEM model was constructed for reappearing mesoscopic structure *** results show that dry-wet cycles decrease the dynamic compressive strength(DCS)with a maximum reduction of 39.40%,the elastic limit strength is reduced from 41.75 to 25.62 *** sieved fragments obtain the highest crack growth rate during the 23rd dry-wet cycle with a predictable life of 25 cycles for each rock *** pore fractal features of the macropores and micro-meso pores show great differences between the early and late cycles,which verifies the computational statistics analysis of particle *** numerical results show that the failure patterns are governed by the strain in pre-peak stage and the shear cracks are *** dry-wet cycles reduce the energy transfer efficiency and lead to the discretization of force chain and crack fields.

关键词： Underground pumped storage power plant Dry-wet cycles Split Hopkinson pressure bar Macro and micro properties FEM-DEM coupling model Damage characterization

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Solid-liquid extraction for yttrium recovery using porous polymeric resin(XAD-7) functionalized with D_(2)EHpA

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Journal of Rare Earths 2024年第9期42卷 1764-1773,I0005页

作者： p.A.Martínez-Montoya R.G.Sanchez-Alvarado D.Y.Medina-Velazquez M.L.Carrera-Jota p.Garnica-Chávez A.de J.Morales-Ramirez Higher School of Chemical Engineering and Extractive Industries ESIQIEIPNDepartment of Metallurgical EngineeringUPALM S/NCol.LindavistaGustavo A.Madero Cd.de MéxicoC.P07738Mexico Metropolitan Autonomous University Department of MaterialsBasic Sciences and EngineeringAv.San Pablo No.180Col.Reynosa TamaulipasCd.de MéxicoC.P02200Mexico Center for Research and Technological Innovation CIITECIPNCda.de CECATIs/nSanta CatarinaAzcapotzalcoC.P02250CDMXMexico

The recovery of yttrium is proposed by applying a solid-liquid extraction process using di-2-ethyl hexylphosphoric acid(D2EHpA) as extracting *** extracting agents were supported on a macro porous polymeric resin XAD-7(solid phase).Yttrium ions extraction and discharge tests were performed,firstly from a synthetic aqueous solution of 100 mg/L Y(liquid phase) at 25℃ with *** effects of pH of aqueous solutions bearing yttrium,volume fraction of extracting agents and the solid/liquid(S/L)ratio on the yttrium recovery were *** most favorable conditions for yttrium ions extraction are;20 vol% D_(2)EHpA functionalized resin,pH=1.5 and an S/L ratio of 10 mg/mL The discharge of yttrium ions was done under the same conditions of extraction stage,using a 2 mol/L [H_(2)SO_(4)] as stripping *** to 80% yttrium is extracted,while 75% yttrium is recovered in the striping *** all experiments,the reaction equilibrium is reached after 20 min,and the kinetics for the extraction stage was determined as a second-order ***,experiments were carried out to discharge the yttriumloaded resins,and it has been determined that the best pH value to strip the Y ions is *** tests of extraction and discharge for yttrium ions show that the functionalized resin can work at least five cycles without decreasing its ***,the proposed process was tested in a real solution with Y ions fro m a waste fluorescent la mp powder leached in H_(2)SO_(4),demonstrating the ability to effectively recover yttrium,separating it from various metals from the studied residue.

关键词： Yttrium recovery Rare earth solid-liquid extraction XAD-7 resin Fluorescent lamps recycling Solid-liquid kinetics extraction

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Laser-induced graphene-coated wearable smart textile electrodes for biopotentials signal monitoring

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Frontiers of Materials Science 2024年第1期18卷 95-111页

作者： C.M.Vidhya Yogita Maithani Sakshi Kapoor J.p.Singh Department of physics Indian Institute of Technology DelhiHauz KhasNew Delhi 110016India

This paper describes how to produce a wearable dry electrode at a reasonable cost and how to use it for the monitoring of biopotentials in *** textiles in wearable technologies have made a great advancement in the health care management and living standards of *** was manufactured using the low-cost single-step process,laser ablation of polyimide,a commercial *** dispersions were made using solvent isopropyl alcohol which has low boiling point,nontoxicity,and environmental *** successive coating of the graphene dispersion on the cotton fabric to make it conductive,the sheet resistance of the resulting fabric dropped to 3% of its initial *** laser-induced graphene(LIG)cotton dry electrodes thus manufactured are comparable to Ag/AgCl wet electrodes in terms of the skin-to-electrode impedance,measuring between 78.0 and 7.2 kΩ for the frequency between 40 Hz and 1 *** LIG cotton electrode displayed a signal-to-noise ratio of 20.17 *** to its comfort,simplicity,and good performance over a longer period of time,the textile electrode appears suited for medical applications.

关键词： biopotential electrocardiogram electromyogram flexible electrode textile porous graphene

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Investigation of Microstructure, Microhardness and Thermal properties of Ag-In Intermetallic Alloys prepared by Vacuum Arc Meltings

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Journal of Wuhan University of Technology(Materials Science) 2024年第1期39卷 182-187页

作者： ÇELİK Erçevik ATA ESENER pınar ÖZTÜRK Esra AKSÖZ Sezen Nevşehir HacıBektaşVeli University Department of Physics50300NevşehirTurkey Erciyes University Graduate School of Natural and Applied Sciences38039KayseriTurkey Kocaeli University Department of Physics41380KocaeliTurkey

Ag-In intermetallic alloys were produced by using vacuum arc furnace. Differential Scanning Calorimetry(DSC) and Energy Dispersive X-Ray Spectrometry(EDX) were used to determine the thermal properties and chemical composition of the phases respectively. Microhardness values of Ag-In intermetallics were calculated with Vickers hardness measurement method. According to the experimental results, Ag-34 wt%In intermetallic system generated the best results of energy saving and storage compared to other intermetallic systems. Also from the microhardness results, it was observed that intermetallic alloys were harder than pure silver and Ag-26 wt%In system had the highest microhardness value with 143.45 kg/mm^(2).

关键词： thermal properties microstructure characterization microhardness alloys material characterization

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Technological advancements in millet dehulling and polishing process: An insight into pretreatment methods, machineries and impact on nutritional quality

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Grain & Oil Science and Technology 2024年第3期7卷 186-195页

作者： Shagolshem Mukta Singh Jayasree Joshi T p.Srinivasa Rao Agricultural and Food Engineering Department Indian Institute of Technology KharagpurKharagpurWest Bengal 721302India

Millets are widely recognized for their nutritional significance;however, the methods employed for their processing are currently lacking. This article primarily focuses on the advanced technologies and progressions in millet dehulling and polishing. These technologies operate based on the fundamental principles of compression-shearing, abrasion-friction, and centrifugal-impact forces. processing of millets can be challenging because of the physical characteristics and tight attachment of hull and bran to the endosperm. However, several dehullers have been designed to solve this problem for different kinds of millets. In addition, the nutritional and anti-nutritional characteristics undergo alterations due to both dehulling and polishing processes. These alterations are thoroughly examined and discussed in this article. Specifically, anti-nutrients such as tannins and phytate are predominantly found in the outer pericarp of the grain and experience a reduction after undergoing dehulling and polishing. The nutritional properties are also subjected to a reduction;however, this reduction can be mitigated by subjecting the grains to certain pretreatments before dehulling and polishing. These treatments serve to enhance dehulling efficiency and nutrient digestibility while simultaneously reducing the presence of anti-nutrients. Novel thermal and non-thermal methodologies such as microwave, hydrothermal, high-pressure processing, and ohmic heating can be employed for processing millets, thereby diminishing the loss of nutrients. Additional research can be carried out to investigate their impact on the dehulling and polishing of millets.

关键词： Millets Dehulling polishing pretreatment Novel thermal and non-thermal techniques

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Stability Analysis of DC Microgrid Clusters Based on Step-by-step System Matrix Building Algorithm

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Journal of Modern power Systems and Clean Energy 2024年第3期12卷 900-912页

作者： K.Jithin N.Mayadevi R.Hari Kumar V.p.Mini the Department of Electrical Engineering College of Engineering TrivandrumAPJ Abdul Kalam Technological University(APJAKTU)ThiruvananthapuramIndia

DC microgrids(DCMGs)are made up of a network of sources and loads that are connected by a number of power electronic converters(pECs).The increase in the number of these pECs instigates major concerns in system *** interconnecting the microgrids to form a cluster,the system stability must be *** paper proposes a novel stepby-step system matrix building(SMB)algorithm to update the system matrix of an existing DCMG cluster when a new microgrid is added to the cluster through a distribution *** stability of the individual DCMGs and the DCMG cluster is analyzed using the eigenvalue ***,the particle swarm optimization(pSO)algorithm is used to retune the controller gains if the newly formed cluster is not *** simulation of the DCMG cluster is carried out in MATLAB/Simulink environment to test the proposed *** results are also validated using the Op4510 real-time simulator(RTS).

关键词： Converter DC microgrid cluster eigenvalue interconnection particle swarm optimization system stability system matrix

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Flame Structure of Methane and Kerosene Combustion with a Compact Concave Flame-Holder using the LES-pdf Method

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Journal of Thermal Science 2024年第1期33卷 222-234页

作者： WANG Fang WANG Yunfan WEI Guanyi LIU Denghuan JIN Jie JONES p.William School of Energy and power Engineering Beihang UniversityBeijingBeijing 100191China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

Compact flame-holders for afterburners are an increasing requirement for modern aero ***,flame-holder design is non-trivial since high inlet temperatures,velocities,and elaborate structures induce complex turbulence,combustion,and spray coupling in modern *** this work,the LES-pdf and stochastic fields-Lagrangian particle spray methods are used to investigate methane and aviation kerosene combustion structures formed by new-type concave *** flow pattern,combustion mode,and flame structure of gaseous and liquid fuel around a concave flame-holder are analyzed,discussed,and compared with experimental *** reveal that the flame stability of a concave flame-holder is better than that of the non-concave ***,when using liquid fuel,the concave flame-holder forms a stable and compact *** results suggest concave flame-holders are a promising design for compact afterburners.

关键词： concave structure flame-holder LES-pdf spray combustion flame structure AECSC

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Subject Area Risk Assessment of Four Hungarian Universities with a View to the QS University Rankings by Subject

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Journal of Data and Information Science 2022年第4期7卷 61-80页

作者： p.ter Sasvári Anna Urbanovics public Governance and International Studies University of Public ServiceHungary University of Miskolc Hungary

purpose:The aim of our paper is to investigate the role of a mentor leading a research team in the overall scientific performance of an academic institution and the possible risks of their departure with a special attention to their publication ***/methodology/approach:By using SciVal subject area data,we composed a formula describing the level of vulnerability of any given university in the case of losing any of its leading mentors,identifying other risk factors by dividing their careers into separate ***:It turns out that the higher field-weighed citation impact is,the better position universities reach in the rankings by subject and the vulnerability of institutions highly depends on the mentors,especially in view of their contribution to the topic *** limitations:The analysis covers the publication output of leading researchers working at four Hungarian universities,the scope of the analysis is worth being *** implications:Our analysis has the potential to give an applicable systemic approach as well as a data collection scheme to university managements so as to formulate an inclusive and comprehensive research strategy involving the introduction of a reward system aimed at publications and further encouraging national and international research ***/value:The methodology and the principles of risk assessment laid down in our paper are not restricted to measuring the vulnerability level of a limited group of academic institutions,they can be appropriately used for investigating the role of mentors or leading researchers at every university across the globe.

关键词： QS Rankings by Subject Scientific Competitiveness Risk Analysis Subject Area Exposure

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Spatio-temporal variability in microfossil and geochemical records of Cenomanian-Turonian oceanic anoxic event-2: a review

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Journal of palaeogeography 2024年第4期13卷 646-674页

作者： C.p.Sooraj Shweta Gupta Jahnavi punekar Department of Earth Sciences Indian Institute of Technology Bombay

The Cenomanian-Turonian boundary oceanic anoxic event(OAE-2; Bonarelli event; ～94 Ma) is associated with a species turnover in the marine calcareous microfossil record, widespread marine anoxia,black shale deposition and positive δ13C excursions. This study reviews 141 CTBE sites globally, aiming to understand micropaleontological, geochemical, and sedimentological expressions of OAE-2. There is a clear palaeogeographic and palaeobathymetric heterogeneity in the development of OAE-2 marine anoxia. A majority of the documented OAE-2 sites are from deep marine environments. The calcareous nannoplankton and benthic foraminifera record a diversity decline, while planktic foraminifera shows community level shifts and no major mass extinction. The variability of total organic carbon in OAE-2 sediments across sites(10 wt.%) and the δ13C profiles(diachronous) have been attributed to different mechanisms of anoxia *** increased primary “productivity model” gains support from productivity proxies(e.g., Ba, p, Cu, Ni),redox-sensitive elements(e.g., Mn, Mo, U, V, As), and eutrophic genera(e.g., benthic foraminifera Gabonita spp., calcareous nannofossils Biscutum spp. and Zeugrhabdotus erectus). The enhanced organic carbon“preservation model” in stratified(semi) restricted basins gains support from sites with lower enrichment of redox-sensitive elements and oligotrophic flora and fauna in the OAE-2 records. Geochronology of the Caribbean and the High Atlantic Large Igneous province events(CLIp and HALIp) mark them as likely triggers of the OAE-2 related global perturbation of marine biogeochemistry. Volcanic triggers may have caused climate warming, altered hydrological cycles, enhanced continental weathering, shifts in ocean circulation, and nutrient flows. Addressing knowledge gaps, further research is urged, utilizing innovative proxies, and exploring underrepresented depositional systems to comprehensively understand OAE-2 onset and biotic crisis.

关键词： Oceanic Anoxic Event-2 Global organic carbon distribution Geochemical proxies Marine calcifiers palaeoceanography

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primary repair of esophageal atresia Gross type C via thoracoscopic magnetic compression anastomosis:Is it the best option?

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World Journal of Gastrointestinal Surgery 2024年第5期16卷 1474-1481页

作者： Sonia pérez-Bertólez Jorge Godoy-Lenz Department of pediatric Surgery Sant Joan de Deu HospitalUniversity of BarcelonaBarcelona 08950Spain Department of pediatric Surgery Clínica Alemana of SantiagoSantiago 7650568Chile

Magnetic compression anastomosis is a promising treatment option for patients with complex esophageal atresia;but,at the present time,should not be the first therapeutic option in those cases where the surgeon can per... 详细信息

关键词： Esophageal atresia Tracheoesophageal fistula Thoracoscopy Magnamosis Magnetic anastomosis

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