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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.a.ound *** 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 cons.a.tly 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.a.d possibly tribological *** high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is.a.hieved 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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Analysis of the Impact of the Blazhko Effect Both on the Van Hoof Effect and Radial Velocity Amplitude in the s.a. RR Lyr

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Res.a.ch in Astronomy and Astrophysics 2024年第6期24卷 253-272页

作者： Y.el jariri F.L.sefyani A.Benhida Z.Benkhaldoun K.Kolenberg K.Chafouai A.Habib M.sabil Observatoire de l'Oukaimeden LPHEAFSSMUniversitéCadi AyyadMarrakech2390Morocco Observatoire de l'Oukaimeden LPHEAFSTGUniversitéCadi AyyadMarrakech549Morocco Département de physique Universitéd'Anvers Avenue Groenenborger 171Anvers2020Belgium LICPM ENSA-BMUniversitéSultan Moulay SlimaneBeni-Mellal23020Morocco

The Van Hoof effect is.a.phase shift existing between the radial velocity curves of hydrogen and metallic lines within the atmosphere of pulsating *** this.a.ticle,we present a study of this phenomenon through the spectra of the brightest pulsating s.a. RR Lyr of RR Lyrae s.a.s recorded for 22 *** based ourselves,on the one hand,on 1268 spectra(41 nights of observation)recorded between the years 1994 and 1997 at the Observatory of Haute Provence(OHP,France)previously observed by Chadid and Gillet,and on the other hand on 1569 spectra(46nights of observation)recorded at our Oukaimeden Observatory(Morocco)between 2015 and *** this study,we have detected information on atmospheric dynamics that had not previously been ***,the Van Hoof effect which results in a clear correlation between the radial velocities of hydrogen and those of the metallic lines has been observed and analyzed at different Blazhko phases.a.correlation between the radial velocities of different metallic lines located in the lower atmosphere has been observed as *** the first time,we were able to show that the amplitude of the radial velocity curves deduced from the lines of hydrogen and that of FeⅡ(λ4923.921?)increases toward the minimum of the Blazhko cycle and decreases toward the maximum of the same Blazhko ***,we found that the Van Hoof effect is.a.so modulated by the Blazhko ***,toward the minimum of the Blazhko cycle the Van Hoof effect is more visible and at the maximum of the Blazhko cycle,this effect is *** also observed the temporal evolution of the amplitudes of the radial velocities of the lower and upper *** observed over a long time,we can interpret it as.a.function of the Blazhko phases.

关键词： s.a.s.a.mospheres s.a.s:variables:RR Lyrae shock waves techniques:spectroscopic techniques:radial velocities s.a.s:individual(RR Lyr)

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Designing a Protection scheme in Micro-Grid systems with DG Using Central Protection Unite and Multiple setting Group Protection Relays

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Journal of Power and Energy Engineering 2024年第9期12卷 37-49页

作者： Mos.a.a I. saleh Gaber el-s.a.y Ali M. Yousef el-Noby A. Ibrahim Alfanar Company Mecca Saudi Arabia Department of electrical Engineering Faculty of Engineering Asyut University Asyut Egypt

Distributed generators now is widely used in electrical power networks, in some cases it works s.a.onally, and some types works.a. special weather conditions like photo voltaic systems.a.d wind energy, and due to this continuous changes in generation condition, the fault current level in network will be affected, this changes in fault current level will affect in the coordination between protection relays.a.d to keep the coordination at right way, an adaptive protection system is required that can adaptive its setting according to generation changes, the fault current level in each case is evaluated using ETAP software, and the required relay setting in each case is.a.so evaluated using Grey Wolf Optimizer (GWO) algorithm, and to select suitable setting which required in each condition, to select the active setting group of protection relay according to generation capacity, central protection unite can be used, and to improve protection s.a.ility and minimizing relays tripping time, a proposed method for selecting suitable backup relay is used, which leads to decrease relays tripping time and increase system s.a.ility, output settings for relays in all cases.a.hieved our constrains.

关键词： Directional Overcurrent Relay Protection Coordination Distributed Generators Central Protection Unite Multiple setting Group Protection Relay

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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： s.a.bhu 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 aeros.a.e ***,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.a.plied 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.a.d 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.a.d 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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Combining ability of Egyptian cotton(Gossypium barbadense L.)reveals genetic potential for improved yield and fiber quality

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Journal of Cotton Res.a.ch 2024年第2期7卷 109-122页

作者： Abdelghany Ahmed M. el-Banna Aly A.A. Lamlom sobhi F el-sorady Gawhara A. salama Ehab A.A. Ren Honglei s.a.bu Abdulwahab s. Yehia Waleed M.B. Crop science Department Faculty of AgricultureDamanhour UniversityDamanhour 22516Egypt Plant Production Department Faculty of Agriculture Saba BashaAlexandria UniversityAlexandria 21531Egypt Agricultural Botany Department Faculty of Agriculture Saba BashaAlexandria UniversityAlexandria 21531Egypt Heilongjiang Academy of Agricultural sciences Soybean Research InstituteHarbin 150086China Department of Agronomy Bayero University KanoKano 700001Nigeria Cotton Breeding Department Cotton Research InstituteAgriculture Research CenterGizaEgypt

Background As the most widely cultivated fiber crop,cotton production depends on hybridization to unlock the yield potential of current varieties.a.deep unders.a.ding of genetic dissection is crucial for the cultivation of enhanced hybrid plants with desired traits,such as high yield and fine fiber *** this study,the general combining ability(GCA)and specific combining ability(s.a.of yield and fiber quality of nine cotton parents(six lines.a.d three testers.a.d eighteen F1 crosses produced using a line×tester mating design were *** The results revealed significant effects of genotypes,parents,crosses.a.d interactions between parents.a.d crosses for most of the studied ***,the effects of both additive and non-additive gene actions played a notably significant role in the inheritance of most of the yield and fiber quality *** F1 hybrids of(Giza 90×Aust)×Giza 86,Uzbekis.a. 1×Giza 97,and Giza 96×Giza 97 demonstrated superior performance due to their favorable integration of high yield attributes.a.d premium fiber quality *** analysis revealed that lint yield has the highest positive direct effect on seed cotton yield,while lint percentage showed the highest negative direct effect on seed cotton *** component analysis identified specific parents.a.d hybrids.a.sociated with higher cotton yield,fiber quality,and other agronomic *** This study provides insights into identifying potential single-and three-way cross hybrids with superior cotton yield and fiber quality characteristics,laying a foundation for future res.a.ch on improving fiber quality in cotton.

关键词： Gossypium barbadense L. Combining ability seed cotton yield Fiber quality Cluster analysis Path analysis

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study of Hygrothermal Behavior of Bio-sourced Material Treated Ecologically for Improving Thermal Performance of Buildings

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Journal of Renewable Materials 2024年第5期12卷 1007-1027页

作者： soumia Mounir Miloudia s.a.ui Youssef Maaloufa Fatima Zohra el Wardi Yakubu Aminu Dodo sara Ibn-elhaj Abdelhamid Khabbazi National school of Architecture Agadir New Complex Ibn Zohr AgadirHay dakhla80000Morocco EMDD CERNE2DUniversity Mohammed V in RabatEst SaléSaléMedinaMorocco Physics Department LPMAT LaboratoryFaculty of Sciences Ain ChockHassan II UniversityCasablancaMorocco Architectural Engineering Department College of Engineering Najran UniversityNajran66426Saudi Arabia The Centre of scientific and Engineering Res.a.ch Najran UniversityNajranSaudi Arabia

Creating sus.a.nable cities is the only way to live in a clean environment,and this problem can be solved by using bio-sourced and recycled *** this purpose,the authors contribute to the valuation of sheep wool waste as.a. eco-friendly material to be used in *** paper investigates the thermal,hygrothermal,and biological aspects of sheep wool by testing a traditional *** biological method of aerobic mesophilicﬂora has been *** X was used to determine the chemical composition of the materials ***,thermal characterization has been *** thermal conductivity is.a.ove 0.046(W·m^(-1)·K^(-1))and the thermal diffusivity is 1.56.10^(-6) m^(2)·s^(-1).Besides,the energy efﬁciency of using sheep wool in buildings was ***,its humidity behavior was evaluated in different aspects in both winter and *** of biological analyses show the efﬁciency of the treatment by removing the majority of the microorgan-isms:the value of yeast and mildew was reduced from 38.10^(2) to 2.10^(2)(UFC·g^(-1)).In addition to that,sheep wool permits obtaining a low thermal transmittance on the s.a.e of the walls.a.d low cooling needs on the s.a.e of the building with a gain of 45%and 52%,respectively.

关键词： sus.a.nability sheep wool biological treatment hygrothermal wool behavior hot wire method

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stem cell transplantation in cerebrovascular accidents.a.global bibliometric analysis(2000-2023)

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World Journal of stem Cells 2024年第9期16卷 832-841页

作者： Jad el Masri Ahmad Afyouni Maya Ghazi Karim Hamideh Is.a. Moubayed Abdo Jurjus Hanine Haidar Ruzanna Petros.a. Pas.a.e salameh Has.a. Hosseini École Doctorale sciences de la Vie et de la santé UniversitéParis-Est CréteilCréteil 94010France INsERM U955-E01 Institut Mondor de Recherche BiomédicaleUniversitéParis-Est CréteilCréteil 94000France Faculty of Medical sciences Lebanese UniversityBeirut 1533Lebanon Department of Anatomy Cell Biology and Physiological SciencesFaculty of MedicineAmerican University of BeirutBeirut 1107Lebanon Department of Neurology Faculty of MedicineLebanese American UniversityBeirut 1102Lebanon Department of Pathology Faculty of MedicineLebanese American UniversityBeirut 1102Lebanon Faculty of Pharmacy Lebanese UniversityBeirut 1102Lebanon Faculty of Medicine Lebanese American UniversityBeirut 1102Lebanon Department of Primary Care and Population Health University of Nicosia Medical SchoolNicosia 2408Cyprus Institut National de santéPublique d'Épidémiologie Clinique et de Toxicologie-Liban Beirut 1103Lebanon Department of Neurology Henri Mondor HospitalAP-HPCréteil 94000France

BACKGROUND Cerebrovascular accident(CVA)is.a.major global contributor to death and *** part of its medical management,res.a.chers have recognized the importance of promising neuroprotective strategies,where stem cell transplantation(sCT)is thought to confer advantages via trophic and neuroprotective *** To evaluate the current s.a.e of res.a.ch on sCT in patients with CVA,assess key trends.a.d highlight literature *** PubMed was screened for sCT in CVA-related articles in October 2023,for each country during the period between 2000 and *** the World Bank data,total population and gross domestic product were collected for ***_1.6.19 was used to create the VOs figure using the results of the same *** and tables were obtained using Microsoft Office *** A total of 6923 studies were identified on sCT in CVA,making 0.03%of all published studies ***,68%were conducted in high-income countries,with a significant focus on mesenchymal stem *** journal“stroke”featured the largest s.a.e of these articles,with mesenchymal sCT having the highest rate of inclusion,followed by hematopoietic *** time,there has been a noticeable shift from in vitro studies,which assess stem cell proliferation and neurogenesis,to in vivo studies.a.med at evaluating efficacy and ***,the number of reviews increased along this *** This bibliometric analysis provides.a.comprehensive guide for physicians.a.d res.a.chers in the field through an objective overview of res.a.ch activity,and highlights both current trends.a.d *** a potential therapeutic role in CVA,more res.a.ch is needed in the future to focus on different aspects of sCT,aiming to reach a better treatment strategy and improve life quality in patients.

关键词： Bibliometric analysis PubMed stem cell transplantation Cerebrovascular accidents stroke

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Optimizing wind farm layout for enhanced electricity extraction using a new hybrid PsO-ANN method

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Global Energy Interconnection 2024年第3期7卷 254-269页

作者： Mariam el Jaadi Touria Haidi Abdelaziz Belfqih Mounia Farah Atar Dialmy LAGEs Laboratory Hassania School of Public Works(EHTP)Casablanca 20230Morocco LEsE Laboratory National School of Electricity and Mechanics(ENSEM)Casablanca 20100Morocco LAGCET Laboratory Hassania School of Public Works(EHTP)Casablanca 20230Morocco

With the growing need for renewable energy,wind farms.a.e playing an important role in generating clean power from wind *** best wind turbine architecture in a wind farm has.a.major influence on the energy extraction *** paper describes.a.unique strategy for optimizing wind turbine locations on a wind farm that combines the capabilities of particle s.a.m optimization(PsO)and artificial neural networks.a.Ns).The PsO method was used to explore the solution s.a.e and develop preliminary turbine layouts.a.d the ANN model was used to fine-tune the placements based on the predicted energy *** proposed hybrid technique seeks to increase energy output while considering site-specific wind patterns.a.d topographical *** efficacy and superiority of the hybrid PsO-ANN methodology are proved through comprehensive simulations.a.d comparisons with existing approaches,giving exciting prospects for developing more efficient and sus.a.nable wind *** integration of ANNs.a.d PsO in our methodology is of paramount importance because it leverages the complementary strengths of both ***,this novel methodology harnesses historical data through ANNs to identify optimal turbine positions that align with the wind speed and direction and enhance energy extraction efficiency.A notable increase in power generation is observed across various *** percentage increase in the power generation ranged from approximately 7.7%to 11.1%.Owing to its versatility and adaptability to site-specific conditions,the hybrid model offers promising prospects for advancing the field of wind farm layout optimization and contributing to a greener and more sus.a.nable energy future.

关键词： Layout optimization Turbine placement Wind energy Hybrid optimization Particle s.a.m optimization Artificial neural networks Renewable energy Energy efficiency

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Ren-integrable and ren-symmetric integrable systems

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Communications in Theoretical Physics 2024年第3期76卷 62-69页

作者： s Y Lou school of Physical science and Technology Ningbo UniversityNingbo315211China

A new type of symmetry,ren-symmetry,describing anyon physics.a.d corresponding topological physics,is ***-symmetry is.a.generalization of super-symmetry which is widely applied in super-symmetric physics such as super-symmetric quantum mechanics,super-symmetric gravity,super-symmetric string theory,super-symmetric integrable systems.a.d so *** and Grass.a.n numbers.a.e,in some sense,dual conceptions.a.d it turns out that these conceptions coincide for the ren situation,that is.a.similar conception of ren-number(R-number)is devised for *** particular,some basic results of the R-number and ren-symmetry are exposed which allow one to derive,in principle,some new types of integrable systems including ren-integrable models.a.d ren-symmetric integrable *** examples of ren-integrable KdV-type systems.a.d ren-symmetric KdV equations.a.e explicitly given.

关键词： symmetries integrable systems anyon physics extended supersymmetry ren-symmetry

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Development and Validation of a s.a.ed electric Combat Vehicle Tire Model

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World Journal of Engineering and Technology 2024年第1期12卷 24-39页

作者： Haniyeh Fathi Aricha Mehrotra Zeinab el-sayegh Department of Automotive and Mechatronics Engineering Ontario Tech University Oshawa Canada

Pneumatic tire modeling and validation have been the topic of several res.a.ch papers, however, most of these papers only deal with pneumatic passenger and truck tires. In recent years, wheeled-s.a.ed vehicles have gained lots of attention as.a.feasible testing platform, nonetheless up to the authors’ knowledge there has been no res.a.ch regarding the use of s.a.ed tires.a.d their effect on the overall vehicle performance characteristics. This paper presents.a.novel s.a.ed electric combat vehicle tire model and validation technique. The pro-line lockdown tire size 3.00 × 7.35 is modeled using the Finite element Analysis (FEA) technique and several materials including layered membrane, beam elements, and Mooney-Rivlin for rubber. The tire-rim assembly is then described, and the rigid body analysis is presented. The tire is then validated using an in-house custom-made s.a.ic tire testing machine. The tire test rig is made specifically to test the pro-line tire model and is designed and manufactured in the laboratory. The tire is validated using vertical stiffness.a.d footprint tests in the s.a.ic domain at different operating conditions including several vertical loads. Then the tire is used to perform rolling resis.a.ce and steering analysis including the rolling resis.a.ce coefficient and the cornering stiffness. The analysis is performed at different operating conditions including longitudinal speeds of 5, 10, and 15 km/h. This tire model will be further used to determine the tractive and braking performance of the tire. Furthermore, the tire test rig will also be modified to perform cornering stiffness tests.

关键词： Tire Modeling Tire Testing Machine Vehicle Dynamics Unmanned Vehicle Modeling Finite element Analysis Tire Mechanics

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