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Effect of Different Amounts of Graphite on the Sintering and Transverse Rupture Properties of Powder Metal Parts

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Journal of Materials Science & Technology 2006年第3期22卷 419-422页

作者： mustafa boz Adem Kurt Karabuk Technical Education Faculty Zonguldak Karaelmas University Karabuk 78050 Turkey Technical Education Faculty Gazi University Besevler 06500 Ankara Turkey

Iron powders were mixed with graphite powders by 1-15 wt pct to produce block samples using powder metallurgy technique. The powders were blended in a three dimensional blender for 20 min and compacted in a die under 500 MPa by using a one directional press. Sinterability and mechanical properties of the samples with different carbon content were investigated. Sintering process was carried out on a belt furnace with flame curtain in dissociated ammonia atmosphere. Block samples produced were suitable for ASTM B-312 transverse rupture strength test apparatus and were tested with 0.050 kN/s velocity in a press under 100 g load. It was found that graphite amount up to 2 wt pct increased the contact area of particles and acted as a lubricant to affect the sintering behaviour positively. The results indicated that the samples containing up to 5 wt pct showed good sintering behaviour and also good hardness due to an increase in pearlite amount. However, the samples containing higher amount of graphite （more than 5 wt pct） affected the sintering behaviour negatively due to the settlement of free graphite around the Fe powders, which resulted in a decrease in the hardness and transverse rupture strength.

关键词： Powder metallurgy Sintering Fe Graphite Transverse rupture strength

Investigation of the compressibility and sinterabilty of AZ91 powder production and particle production by gas atomisation method

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Journal of Magnesium and Alloys 2019年第3期7卷 400-413页

作者： Mehmet Akkas mustafa boz Faculty of Engineering and Architecture Department of Mechanical EngineeringKastamonu UniversityTurkey Faculty of Technology Department of Manufacturing EngineeringKarabiik UniversityKarabiikTurkey

This study intends to determine the pressability and sinterability of AZ91 powder production by gas atomisation method and that of the produced powder for partial ***,first,a gas atomisation unit has been designed and manufactured in the laboratories of the Karabiik University,Department of Manufacturing *** powder production has been achieved at a temperature of 795℃,with nozzle diameters of 2 and 4 mm and four different gas pressures(5,15,25,35 bars).Argon gas has been used for atomisation and as a protective gas *** electron microscope(SEM)is used to determine the shape of the produced AZ91 powder,and a laser particle size analyzer is used to analyze the powder ***,a microhardness(HV0.025)measurement has been conducted to determine the hardness of the produced *** achieve a homogeneous distribution,the produced powders are mixed in a three-dimensional moving turbulator for 30 *** powders have been pressed at 300,400,500 and 600 MPa and have been sintered at 500℃,550℃and 600℃.Additionally,the density values have been determined before and after sintering of the *** images have been obtained from the fractured surfaces of the samples before and after *** and EDX analyses have been performed to determine the chemical ***,microhardness(HV0.5)is obtained from the pressure surfaces of the samples to determine the effects of the pressing pressure and the sintering temperature on the *** a result of the experimental studies,it has been observed that the powder size decreases with the increase in gas pressure and that the powder shape generally changes from ligament and complex shape to droplet and spherical *** the XRD,XRF and EDX results,it has been determined that the structure comprises an a phase(Mg main matrix)and Mg17Al12 interphase,which isβphase,and very small amounts of MgO have been *** hardness of the produced powders increas

关键词： Gas atomisation AZ91 alloy powder Gas pressure Nozzle diameter Pressing Sintering

Determining the surface fault-rupture hazard zone for the Pazarcık segment of the East Anatolian fault zone through comprehensive analysis of surface rupture from the February 6,2023,Earthquake(Mw 7.7)

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Journal of Mountain Science 2024年第8期21卷 2646-2663页

作者： mustafa SOFTA Dokuz Eylul University Department of Geological Engineering Izmir 35390Türkiye Kansas State University Department of Geology Manhattan 66506KansasUSA

Following surface rupture observations in populated areas affected by the KahramanmaraşEarthquake(Mw 7.7)on February 6th,2023,along the Pazarcık segment of the East Anatolian Fault Zone(EAFZ),this study presents novel insights into physical criteria for delineating surface fault-rupture hazard zones(SRHZs)along ruptured strike-slip *** achieve this objective,three trench studies across the surface rupture were conducted on the Pazarcık segment of the EAFZ to collect field data,and earthquake recurrence intervals were interpreted using Bayesian statistics from previously conducted paleoseismological *** results of the proposed model indicate that the Pazarcık segment produced five significant surface-rupturing earthquakes in the last∼11 kyr:E1:11.13±1.74 kyr,E2:7.62±1.20 kyr,E3:5.34±1.05 kyr,E4:1.82±0.93 kyr,and E5:0.35±0.11 *** addition,the recurrence intervals of destructive earthquakes on the subject in question range from 0.6 kyr to 4.8 *** that the last significant earthquake occurred in 1513,the longest time since the most recent surface fault rupturing earthquake on this particular segment was 511 *** results indicate that,in terms of the theoretical recurrence interval of earthquakes that can create surface ruptures on the Pazarcık segment,the period in which the February 6,2023,earthquake occurred was within the end of the expected return *** a result,the potential for a devastating earthquake in the near future is not foreseen on the same ***,the SRHZ proposed for the Pazarcık section of Gölbaşıvillage was calculated as a 61-meter-wide offset on the fault lineament to reduce the negativities that may occur in the ruptured area in the *** is recommended to take into account this width in the settlement of this area and nearby areas.

关键词： Surface rupture Earthquake mitigation Recurrence interval Pazarcık segment East Anatolian Fault Zone(EAFZ)

Persistent currents of ultrarelativistic plasma-encased endofullerene molecules entrapping a H atom

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Communications in Theoretical Physics 2024年第6期76卷 148-164页

作者： mustafa Kemal Bahar Department of Physics Faculty of ScienceSivas Cumhuriyet University58140SivasTurkey

In this work,for the first time in the relevant literature,the persistent currents(PC)and induced magnetic fields(IMF)of an endofullerene molecule entrapping a hydrogen atom,under spherical confinement,are *** endofullerene molecule is enclosed within a spherical region and embedded in a plasma *** plasma environment is depicted with the more general exponential cosine screened Coulomb potential,and its relevant effects are analyzed by considering plasma screening *** relevant model for endohedral confinement is the Woods-Saxon confinement potential,which is compatible with experimental *** effects of various forms of Cn are thoroughly elucidated via the analysis of the confinement depth,spherical shell thickness,the inner radius,and the smoothing *** find the bound states in the spherically confined endofullerene,the decoupling of the second-order Dirac equation for the large and small components of the radial atomic wave functions is *** Dirac equation with the interaction potential is solved numerically by using the Runge-Kutta-Fehlberg method via the decoupling *** influence of spin orientations on the PC and IMF is also *** effects of spherical confinement,plasma shielding,and the structural properties of the fullerene on the PC and IMF are thoroughly ***,under given physical conditions,the optimal ranges of these effects are determined.

关键词： quantum plasma endohedral fullerene persistent current ultrarelativistic interaction induced magnetic field

Film Flow of Nano-Micropolar Fluid with Dissipation Effect

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Computer Modeling in Engineering & Sciences 2024年第9期140卷 2487-2512页

作者： Abuzar Abid Siddiqui mustafa Turkyilmazoglu Department of Basic Sciences&Humanities Faculty of Engineering&TechnologyBahauddin Zakariya UniversityMultanPakistan Department of Mathematics Hacettepe UniversityAnkaraTürkiye Department of Medical Research China Medical University HospitalChina Medical UniversityTaichungTaiwanChina

The physical problem of the thin film flow of a micropolar fluid over a dynamic and inclined substrate under the influence of gravitational and thermal forces in the presence of nanoparticles is *** different types of nanoparticle samples are accounted for in this current study,namely gold Au,silver Ag,molybdenum disulfide MoS_(2),aluminum oxide Al_(2)O_(3),and silicon dioxide SiO_(2).Blood,a micropolar fluid,serves as the common base *** exact closed-form solution for this problem is derived for the first time in the *** results are particularly validated against those for the Newtonian fluid and show excellent *** was found that increasing values of the spin boundary condition and micropolarity lead to a reduction in both the thermal and momentum boundary layers.A quantitative decay in the Nusselt number for a micropolar fluid,as compared to a Newtonian one for all the tested nanoparticles,is *** and silver nanoparticles(i)intensify in the flow parameter as the concentration of nanoparticles increases(ii)yield a higher thermal transfer rate,whereas molybdenum disulfide,aluminum oxide,and silicon dioxide exhibit a converse attitude for both Newtonian and micropolar *** reduction in film thickness for fluid comprising gold particles,as compared to the rest of the nanoparticles,is remarkable.

关键词： Thin film flow micropolar fluid nanoparticles molybdenum disulfide inclined substrate

Green solutions for sustainable development:Introduction

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Geoscience Frontiers 2024年第4期15卷 330-332页

作者： Arshian Sharif mustafa Tevfik Kartal Ugur Korkut Pata Sunway University Malaysia European University of Lefke Türkiye Osmaniye Korkut Ata University Türkiye

The timely mitigation of the ever-increasing environmental damages induced by the use of fossil fuels created demands by dismissing the activities that irreversibly affect the environment(Kartal et al.,2023;Pata et al.,2023).In addition,there is also a need to encourage and persuade activities that generate low carbon dioxide(CO_(2))emissions and allow for sustainable *** achieve sustainable development goals(SDGs)and comply with the Paris Agreement's goals and statements,which aim to limit global warming to 1.5 ℃ and demand net-zero emissions by 2050,an alternative to fossil fuels and CO_(2)-emitting power plants is needed(Kartal et al.,2024).This alternative means relying on clean,green,and renewable energy that will eventually con-tribute to a zero-carbon *** kinds of energy include energy produced by hydro,solar,wind,biomass,biofuels,and geothermal production capacities,along with the future of nuclear fusion(Ozcan et al.,2024).However,since not all of these forms of energy have reached their technological maturity and cost-effectiveness status,therefore policymaking institutions should initiate,develop,and align the policies in supporting the production and distribution of green energy.

关键词： eventually sustainable policy

Blockchain-based governance models supporting corruption-transparency:A systematic literature review

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Blockchain(Research and Applications) 2024年第2期5卷 163-183页

作者： Mohammad mustafa Ibrahimy Alex Norta Peeter Normak School of Digital Technologies Tallinn UniversityNarva mnt 25Tallinn 10120Estonia Baltic Film Media and Arts SchoolTallinn UniversityTallinnEstonia Dymaxion OÜ TallinnEstonia

Corruption and lack of transparency remain critical challenges in governance systems around the *** issues are often perpetuated by centralized systems and their manipulation by system ***,the lack of data ownership and the monetization of user data by tech companies further increase concerns about *** light of these concerns,this study aims to review existing blockchain-based governance models and identify best-practice governance models focusing on corruption transparency,their characteristics,and *** research will also examine the role of a token economy in addressing trusted third-party issues related to asset ownership ***,we discuss the effect of smart contracts,blockchain,decentralized autonomous organizations(DAOs),Web 3.0,and multifactor challenge set self-sovereign identity authentication(MFSSIA)as modern technologies to combat corruption and achieve transparency in the public *** achieve this,we conducted a systematic literature review(SLR)comprising peer-reviewed journals,proceedings,and book chapters published between 2012 and *** the SLR methodology,45 primary and supporting studies have been selected for result extraction and ***,we discovered seven blockchain-based governance models with their characteristics and primary components.

关键词： Blockchain governance Token economy Transparency Smart contract Web 3.0 DAOs

Prediction of landslide tsunami run-up on a plane beach through feature selected MLP-based model

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Journal of Ocean Engineering and Science 2024年第3期9卷 222-231页

作者： Baran Aydın Savas Yaguzluk mustafa Açıkkar Department of Civil Engineering Adana Alparslan Turkes Science and Technology UniversityAdana 01250Turkey Department of Nanotechnology and Engineering Sciences Adana Alparslan Turkes Science and Technology UniversityAdana 01250Turkey Department of Software Engineering Adana Alparslan Turkes Science and Technology UniversityAdana 01250Turkey

We proposed new prediction models based on multilayer perceptron(MLP)which successfully predict the maximum run-up of landslide-generated tsunami waves and assess the role of parameters affecting *** input is approximately 55,000 rows of data generated through an analytical solution employing slide’s cross section,initial submergence,vertical thickness,horizontal length,beach slope angle and the maximum run-up itself,along with its occurrence *** parameters are first ranked through a feature selection algorithm and six models are constructed for a 9,000-row randomly sampled *** MLP-based models led predictions with a minimum Mean Absolute Percentage Error of 1.1%and revealed that vertical slide thickness has the largest impact on the maximum tsunami run-up,whereas beach slope angle has minimal *** parison with existing literature showed the reliability and applicability of the offered *** methodology introduced here can be suggested as fast and flexible method for prediction of landslide-induced tsunami run-up.

关键词： Landslide tsunami Maximum run-up Artificial neural networks Feature selection

Prognostic factors and clinical features of rhino-orbitalmucormycosis cases:an update for patient and visual survivals

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International Journal of Ophthalmology(English edition) 2024年第5期17卷 916-923页

作者： mustafa Aksoy Altan Atakan Ozcan Burak Ulas Department of Ophthalmology Cukurova University Faculty of MedicineSaricamAdana 01330Türkiye

AIM:To determine the frequency of patients’vision survival and prognostic factors and evaluate clinical features in rhino-orbital ***:Forty-three eyes of 43 patients followed up with orbital mucormycosis infections were included in the *** characteristics of the patients,symptoms at admission,ophthalmologic and non-ophthalmologic examination findings,clinical findings during follow-up,medical and surgical procedures,and complications were *** survival was determined by assessing the incidence of mortality,and vision survival was defined as achieving a final visual acuity of at least light ***:Twenty-seven(62.8%)patients were male,and 16(37.2%)were *** the underlying disease status of the patients was examined,it was observed that all patients had an underlying disease and diabetes constituted the majority(65.2%).Periorbital swelling(69.8%)and ophthalmoplegia(53.5%)were the most common symptoms and findings at the admission of patients with mucormycosis *** disease resulted in death in 22(51.2%)*** presence of fever and shorter duration of antifungal therapy were associated with lower patient *** surgery was not found to be associated with the survival of the *** eye,loss of pupillary light reflex,and development of central retinal artery occlusion were associated with lower vision ***:This study presents one of the most extensive patient series in the literature on rhino-orbital *** the patients’symptoms at the time of admission and the clinical findings during the infection process will increase awareness about the disease.

关键词： mucormycosis rhino-orbital-mucormycosis orbital apex syndrome retinal arterial occlusion