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Tribological behavior of lubricant-impregnated porous polyimide

Friction 2024年第4期12卷 711-725页

作者： Jinbang LI Ningning ZHOU Janet s.s.WONg school of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Beijing Key Laboratory of Long-life Technology of Precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100029China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

Porous materials impregnated with lubricants can be used in conditions where limited lubricant is *** this work,three porous polyimides(PPI)with different densities were ***(PAO)impregnated PPI(iPPI)discs were rubbed against steel and sapphire *** operando observations of the iPPI-sapphire contacts show that oil is released under an applied load,forming a meniscus around *** at the outlet is created at high sliding *** amount of released oil increases with increasing PPI *** moduli,E*,estimated based on the actual contact size show that trapped oil in iPPIs contributes to load *** higher speeds,tribological rehydration of the contact occurs in low density iPPI,with that E*rises with *** high density PPIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil *** of iPPI-steel contacts is governed by the mechanical properties of the PPI,the flow of the lubricant,and the roughness of the PPI *** low-and medium-density(highly porous,high roughness)PPIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological *** high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest *** results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions.

关键词： polyimide porous material friction mechanism polymer limited lubrication

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Development of an ultrathin liquid sheet target for laser ion acceleration at high repetition rates in the kilohertz range

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High Power Laser science and Engineering 2024年第3期12卷 134-145页

作者： M.Füle A.P.Kovács T.gilinger M.Karnok P.gaál s.Figul g.Marowsky K.Osvay National Laser-Initiated Transmutation Laboratory University of SzegedSzegedHungary Department of Experimental Physics University of SzegedSzegedHungary ELI ALPs ELI-HU Non-Profit Ltd.SzegedHungary Department of Optics and Quantum Electronics University of SzegedSzegedHungary Advanced Microfluidic systems gmbH GöttingenGermany

A colliding microjet liquid sheet target system was developed and tested for pairs of round nozzles of 10,11 and 18μm in *** sheet's position stability was found to be better than a few *** interaction with 50 mJ laser pulses,the 18μm jet has a resonance amplitude of 16μm at a repetition rate of 33 Hz,while towards 100 Hz it converges to 10μm for all nozzles.A white-light interferometric system was developed to measure the liquid sheet thickness in the target chamber both in air and in vacuum,with a measurement range of 182 nm±1μm and an accuracy of±3%.The overall shape and 3D shape of the sheet follow the Hasson±Peck model in *** vacuum versus air,the sheet gradually loses 10%of its thickness,so the thinnest sheet achieved was below 200 nm at a vacuum level of 10±4mbar,and remained stable for several hours of operation.

关键词： diagnostics laser ion acceleration nanometric liquid sheet targets vacuum test

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Plasma electrolytic formation and characterization of MnWO_(4)/WO_(3) film heterostructures

ChemPhysMater

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ChemPhysMater 2024年第3期3卷 293-302页

作者： M.s.Vasilyeva I.V.Lukiyanchuk Yu.B.Budnikova V.g.Kuryavyi D.H.shlyk g.A.Zverev Department of Chemistry and Materials of Institute of High Technology and Advanced Materials Far Eastern Federal UniversityFEFU CampusVladivostok 690922Russia Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok 690022Russia

MnWO_(4)/WO_(3) p-n heterojunction films were fabricated using a one-step method consisting of the plasma electrolytic oxidation(PEO)of titanium in homogeneous electrolytes containing paratungstate ions and stable watersoluble EDTA-chelated *** influences of the formation current density and W:Mn molar ratio of the electrolyte,which was varied from 1:2 to 2:1,on the composition,morphology,and optical and photocatalytic properties of the resulting coatings were studied.X-ray diffraction analysis,scanning electron microscopy,energy dispersive X-ray analysis,Raman spectroscopy,and ultraviolet diffuse reflectance spectroscopy were used to characterize the formed *** of the W:Mn ratio of the electrolyte,the coatings contained crystalline t-WO_(3) and m-MnWO_(4).Depending on the formation conditions,the optical band gap energies of the composites varied from 2.63 to 3.01 *** largest absorption red shift and lowest band gap energy were observed in the film composite formed in an electrolyte with W:Mn=2:1,at a current density of 0.2 A cm^(−2).Composites obtained in electrolytes with W:Mn ratios of 2:1 and 1:1 exhibited photocatalytic activity in the degradation of rhodamine C and methyl orange dyes in the presence of 10 mmol L^(–1) H2O_(2) under ultraviolet and visible light *** role of hydrogen peroxide in this dye degradation on PEO-coated composites under light irradiation is discussed.

关键词： Plasma electrolytic oxidation Manganese tungstate Tungsten oxide Titanium Optical properties p-n heterojunction

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The magnetosheath at high spectral resolution

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Earth and Planetary Physics 2024年第1期8卷 234-246页

作者： K.D.Küntz D.Koutroumpa W.R.Dunn A.Foster F.s.Porter D.g.sibeck B.Walsh The Henry A.Rowland Department of Physics and Astronomy Johns Hopkins University3701 San Martin DriveBaltimoreMD21218USA NAsA goddard space Flight Center 8800 Greenbelt RoadGreenbeltMD 20771USA LATMOs-OVsQ CNRSUVSQ Paris-SaclaySorbonne Université11 Boulevard d’Alembert78280GuyancourtFrance Department of Physics and Astronomy University College LondonLondonUK The Centre for Planetary science at UCL/Birkbeck Gower StreetLondon WC1E 6BTUK Center for Astrophysics Harvard University&Smithsonian Institution60 Garden StreetCambridgeMA 02138USA Center for space Physics Boston University110 Cummington MallBostonMAUSA

While we eagerly anticipate sMILE’s(solar wind Magnetosphere Ionosphere Link Explorer)unprecedented X-ray observations of the Earth’s magnetosheath and the initiation of a new era of magnetospheric research,it seems appropriate to look ahead to the abilities of the next generation of astrophysics *** these,the Line Emission Mapper(LEM),a large aperture micro-calorimeter based mission,is currently planned to be able to observe the magnetosheath at high spectral resolution(~2 eV).With a field of view of~30′,LEM will allow higher spatial resolution and higher cadence measurement of the motion of a very small portion of the magnetopause over relatively short periods of time(multiple hours),complementing sMILE’s global ***’s strength is its spectral *** will be able to measure the abundance of a broad range of elements and ionization states,many of which are inaccessible to current in situ instruments,and will be able to separate the emission from the magnetosheath from the emission from the cosmic X-ray background using the difference in their relative velocities.

关键词： magnetosheath charge exchange solar wind abundances

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Nanozyme catalysis in a crowded environment:The impact of diffusion and surface shielding

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Nano Research 2024年第7期17卷 5795-5800页

作者： Vasily g.Panferov Juewen Liu Department of Chemistry Waterloo Institute for NanotechnologyWaterlooOntario N2L 3G1Canada

Nanozymes are widely used in various applications as nanosized catalysts for replacing *** accurate estimation of the catalytic activity of nanozymes in real conditions is *** this article,for the first time,we systematically studied the effect of macromolecular molecules co-existing in the real system on the oxidoreductase(peroxidase,oxidase,and catalase)-mimicking nanozymes made of a gold nanoparticle core and a platinum shell,Prussian Blue,Mn_(2)O_(3) and CoO *** were made with horseradish *** distinguished two main mechanisms of the negative impact of macromolecules on nanozyme catalysis—slowed diffusion and surface shielding of *** the first mechanism is typical for enzymes,the second one is specific only for *** the mechanisms is essential for developing approaches to reduce the unavoidable impact of macromolecules for various analytical and biomedical applications.

关键词： molecular crowding biosensors nanoparticles

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Pharmacological methods for ovarian function and fertility preservation in women with cancer:A literature review

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Oncology Research 2024年第8期32卷 1309-1322页

作者： ANA s.CVETANOVIC MATTEO LAMBERTINI KEVIN PUNIE gORANA g.MATOVINA BRKO NIKOLA D.ZIVKOVIC MAJA J.POPOVIC MARIJANA M.MILOVIC KOVACEVIC LAZAR s.POPOVIC Department for Oncology Medical Faculty NisUniversity of NisNis18000Serbia Clinic of Oncology University Clinical Centre NisNis18000Serbia Department of Internal Medicine and Medical sciences(DiMI) School of MedicineUniversity of GenovaGenova16100Italy Department of Medical Oncology U.O.C Clinica di Oncologia MedicaIRCCS Ospedale Policlinico San MartinoGenova16100Italy Department of general Medical Oncology and Multidisciplinary Breast Centre Leuven Cancer InstituteUniversity Hospitals LeuvenLeuven3001Belgium Department of Medical Oncology Oncology Institute of VojvodinaSremska Kamenica21208Serbia Department for Pathology Medical Faculty NisUniversity of NisNis18000Serbia Center for Pathology University Clinical Centre NisNis18000Serbia Faculty of Medicine University of Novi SadNovi Sad21000Serbia Department of Medical Oncology Institute of Oncology and Radiology SerbiaBelgrade11000Serbia

Oncofertility is an extremely signiﬁcant topic that is increasingly being discussed owing to increased evidence indicating that fertility preservation does not affect the treatment outcomes of patients with cancer but signiﬁcantly contributes to preserving life *** effect of chemotherapy can range from minimal effects to complete ovarian *** data are available on the effects of monoclonal antibodies and targeted therapies on the ovaries and *** ovarian suppression by administering a gonadotropin-releasing hormone agonist(gnRHa)during chemotherapy decreases the gonadotoxic effect of chemotherapy,thereby diminishing the chance of developing premature ovarian insufﬁciency(POI).At present,the concomitant administration of gnRH analogs during chemotherapy is the only accepted pharmacological method for preserving ovarian ***,most randomized studies on the effectiveness of luteinizing hormone-releasing hormone agonists during chemotherapy in preventing POI have been conducted in women with breast cancer,with a considerably small number of studies on patients with hematological ***,most randomized controlled trials on breast cancer have revealed a decrease in treatment-induced POI risk,regardless of the hormone receptor *** addition,studies on hematological malignancies have yielded negative results;nevertheless,theﬁndings must be interpreted with caution owing to numerous *** guidelines from the American society of Clinical Oncology and EsMO Clinical Practice guidelines recommend sperm,oocyte,and embryo cryopreservation as a standard practice and only offering gnRHa to patients when proven fertility preservation methods are not *** this manuscript,we present a comprehensive literature overview on the application of ovarian suppression with gnRHa during chemotherapy in patients with cancer by addressing preclinical and clinical data,as well as future perspectives in thisﬁeld

关键词： gonadotropin-releasing hormone agonists(gnRHa) Fertility preservation Premature ovarian insufficiency(POI) Premenopausal patients

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Enhancing fatigue performance of AZ31 magnesium alloy components fabricated by cold metal transfer-based wire arc directed energy deposition through LPB

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Journal of Magnesium and Alloys 2024年第4期12卷 1638-1662页

作者： shambhu Kumar Manjhi srikanth Bontha A.s.s.Balan Department of Mechanical Engineering National Institute of Technology KarnatakaSurathkalSrinivasanagarMangaloreKarnataka 575025India

Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace ***,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing *** this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 *** findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED *** Plasticity Burnishing(LPB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the *** treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress ***,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LPB specimens.A higher fraction of Low Angle grain Boundaries(LAgBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature *** contrast,wrought and WA-DED+LPB specimens displayed a higher percentage of High Angle grain Boundaries(HAgBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue *** findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy *** study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface d

关键词： Wire arc additive manufacturing AZ31 Mg alloy Low plasticity burnishing Low cycle fatigue test strain amplitude

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Optimization of a photovoltaic-battery system using deep reinforcement learning and load forecasting

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Energy and AI 2024年第2期16卷 168-183页

作者： António Corte Real g.Pontes Luz J.M.C.sousa M.C.Brito s.M.Vieira IDMEC Instituto Superior TécnicoUniversidade de LisboaLisboa1049-001Portugal Instituto Dom Luiz Faculdade de CiênciasUniversidade de LisboaCampo Grande1749-016LisboaPortugal

Home Energy Management systems(HEMs)are increasingly relevant for demand-side management at the residential level by collecting data(energy,weather,electricity prices)and controlling home appliances or storage *** control can be performed with classical models that find optimal solutions,with high real-time computational cost,or data-driven approaches,like Reinforcement Learning,that find good and flexible solutions,but depend on the availability of load and generation data and demand high computational resources for *** this work,a novel HEMs is proposed for the optimization of an electric battery operation in a real,online and data-driven environment that integrates state-of-the-art load forecasting combining CNN and LsTM neural networks to increase the robustness of *** Reinforcement Learning agents are trained with different algorithms(Double DQN,Dueling DQN,Rainbow and Proximal Policy Optimization)in order to minimize the cost of electricity purchase and to maximize photovoltaic self-consumption for a PV-Battery residential *** show that the best Reinforcement Learning agent achieves a 35%reduction in total cost when compared with an optimization-based agent.

关键词： Energy management system Deep reinforcement learning Demand-side management Load forecasting Deep learning Energy storage systems

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Analysis of the discrete contact characteristics based on the greenwood-Williamson model and the localization principle

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Friction 2024年第5期12卷 1042-1056页

作者： Anastasiya A.YAKOVENKO Irina g.gORYACHEVA Ishlinsky Institute for Problems in Mechanics RAs Moscow119526Russia

The contact of a rigid body with nominally flat rough surface and an elastic half-space is *** solve the contact problem,the greenwood-Williamson statistical model and the localization principle are *** developed contact model allows us to investigate the surface approach and the real contact area with taking into account the asperities *** is shown that the mutual influence of asperities changes not only contact characteristics at the macroscale,but also the contact pressure distribution at the *** follows from the results,the inclusion in the contact model of the effect of the mutual influence of asperities is especially significant for studying the real contact area,as well as the contact characteristics at high applied *** results calculated according to the proposed approach are in a good agreement with the experimentally observed effects,i.e.,the real contact area saturation and the additional compliance exhaustion.

关键词： surface roughness elasticity greenwood-Williamson model localization principle asperity interaction

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Control system design for a pressure-tube-type supercritical water-cooled nuclear reactor via a higher order sliding mode method

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Nuclear science and Techniques 2024年第1期35卷 145-154页

作者： M.Hajipour g.R.Ansarifar Department of Nuclear Engineering Faculty of PhysicsUniversity of IsfahanIsfahan 81746-73441Iran

Nuclear power plants exhibit non-linear and time-variable ***,designing a control system that sets the reactor power and forces it to follow the desired load is complicated.A supercritical water reactor(sCWR)is a fourth-generation conceptual *** an sCWR,the non-linear dynamics of the reactor require a controller capable of control-ling the *** this study,a pressure-tube-type sCWR was controlled during reactor power maneuvering with a higher order sliding mode,and the reactor outgoing steam temperature and pressure were controlled *** an sCWR,the temperature,pressure,and power must be maintained at a setpoint(desired value)during power *** point kinetics equations with three groups of delayed neutrons were used in the ***-order and classic sliding mode controllers were separately manufactured to control the plant and were compared with the PI controllers speci-fied in previous *** controlled parameters were reactor power,steam temperature,and ***,for these parameters,the PI controller had certain instabilities in the presence of *** classic sliding mode controller had a higher accuracy and stability;however its main drawback was the chattering *** was highly accurate and stable and had a small computational *** reality,it followed the desired values without oscillations and chattering.

关键词： supercritical water nuclear reactor Higher order sliding mode controller steam temperature steam pressure Point kinetics model

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