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Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

Journal of Magnesium and Alloys 2024年第5期12卷 1663-1686页

作者： Gürel Cam Ali Günen Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Mechanical Engineering31200 Iskenderun-HatayTurkey Iskenderun Technical University Faculty of Engineering and Natural SciencesDepartment of Metallurgy and Materials Engineering31200 Iskenderun-HatayTurkey

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport ***,their widespread application is hindered by their low formability at room temperature due to limited slip *** Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high *** casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain *** metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast ***,MAM is a promising technique to produce Mg alloy *** energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive ***,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this *** review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and ***,the predominant imperfections,notably inhomo

关键词： Additive manufacturing DED processes Arc-DED Wire arc additive manufacturing(WAAM) 3-D printing High deposition rate

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Simulation and experimentation of Propeller-Savonius turbine tested underwater surface

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Clean Energy 2024年第3期8卷 20-33页

作者： Sri Wuryanti Teguh Sasono Bambang P.Manunggal Wahyu B.Mursanto Sugianto department of Energy Conversion engineering Politeknik Negeri BandungIndonesia department of Mechanical engineering Politeknik Negeri BandungIndonesia

Indonesia’s vast maritime territory offers a unique opportunity for harnessing the potential Energy of seawater *** study explores the effectiveness of a combined Savonius and propeller-type turbine *** Savonius turbine,known for its efficiency in capturing ocean currents due to its large sweep area,is combined with a propeller-type turbine to enhance rotational speed and power generation.A novel approach is employed to induce turbulence and optimize energy extraction,first channeling water through the propeller turbine and then into the Savonius turbine.A comprehensive investigation is conducted through simulations and experimental tests within a controlled tunnel *** study explores the performance of two-bladed and three-bladed Propeller-Savonius configurations at varying inlet water velocities(0.1,0.3,0.6 and 1.0 m/s).The simulation incorporates a turbulence model with 5%intensity and a hydraulic diameter of 0.216 *** indicate that the proposed configuration achieves a maximum power output of 2.0293 W with an impressive efficiency of 63.339%in ***,experimental testing yields a peak efficiency of 61.335%and turbine power of 0.3951 *** findings demonstrate the feasibility of the combined turbine system and highlight the importance of turbulence in optimizing energy extraction from seawater *** research contributes valuable insights into the design and performance of hybrid turbines for harnessing oceanic Energy,emphasizing the potential for sustainable power generation in maritime *** methodology and results presented herein offer a foundation for further exploration and refinement of seawater current energy conversion technologies.

关键词： hydro-turbine propeller-Savonius renewable energy water

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Model Reference Adaptive Controller for Simultaneous Voltage and Frequency Restoration of Autonomous AC Microgrids

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Journal of Modern Power Systems and Clean Energy 2024年第4期12卷 1194-1202页

作者： Farahnaz Ahmadi Yazdan Batmani Hassan Bevrani department of Electrical engineering University of KurdistanSanandajIran

In an autonomous droop-based microgrid,the sys-tem voltage and frequency(VaF)are subject to deviations as load *** the existence of various control methods aimed at correcting system frequency deviations at the second-ary control level without any communication network,the chal-lenges associated with these methods and their abilities to simul-taneously restore microgrid VaF have not been fully *** this paper,a multi-input multi-output(MIMO)model ref-erence adaptive controller(MRAC)is proposed to achieve VaF restoration while accurate power sharing among distributed generators(DGs)is *** proposed MRAC,without any communication network,is designed based on two meth-ods:droop-based and inertia-based *** the microgrid,the suggested design procedure is started by defining a model reference in which the control objectives,such as the desired settling time,the maximum tolerable overshoot,and steady-state error,are ***,a feedback-feedforward con-troller is established,of which the gains are adaptively tuned by some rules derived from the Lyapunov stability *** some simulations in MATLAB/SimPowerSystem Tool-box,the proposed MRAC demonstrates satisfactory perfor-mance.

关键词： AC microgid communication-free secondary control droop-based method inertia-based method model reference adaptive controller(MRAC) simultaneous voltage and frequency restoration

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Relational Turkish Text Classification Using Distant Supervised Entities and Relations

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Computers, Materials & Continua 2024年第5期79卷 2209-2228页

作者： Halil Ibrahim Okur Kadir Tohma Ahmet Sertbas department of Computer engineering Faculty of Engineering and Natural SciencesIskenderun Technical UniversityHatay31200Turkey department of Computer engineering Faculty of EngineeringIstanbul University-CerrahpasaIstanbul34310Turkey

Text classification,by automatically categorizing texts,is one of the foundational elements of natural language processing *** study investigates how text classification performance can be improved through the integration of entity-relation information obtained from the Wikidata(Wikipedia database)database and BERTbased pre-trained Named Entity Recognition(NER)*** on a significant challenge in the field of natural language processing(NLP),the research evaluates the potential of using entity and relational information to extract deeper meaning from *** adopted methodology encompasses a comprehensive approach that includes text preprocessing,entity detection,and the integration of relational *** conducted on text datasets in both Turkish and English assess the performance of various classification algorithms,such as Support Vector Machine,Logistic Regression,Deep Neural Network,and Convolutional Neural *** results indicate that the integration of entity-relation information can significantly enhance algorithmperformance in text classification tasks and offer new perspectives for information extraction and semantic analysis in NLP *** of this work include the utilization of distant supervised entity-relation information in Turkish text classification,the development of a Turkish relational text classification approach,and the creation of a relational *** demonstrating potential performance improvements through the integration of distant supervised entity-relation information into Turkish text classification,this research aims to support the effectiveness of text-based artificial intelligence(AI)***,it makes significant contributions to the development ofmultilingual text classification systems by adding deeper meaning to text content,thereby providing a valuable addition to current NLP studies and setting an important reference point for future research.

关键词： Text classification relation extraction NER distant supervision deep learning machine learning

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Dynamic and electrical responses of a curved sandwich beam with glass reinforced laminate layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact

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Applied Mathematics and Mechanics(English Edition) 2024年第1期45卷 155-178页

作者： N.SHAHVEISI S.FELI department of Mechanical engineering Razi UniversityKermanshah ***Iran

The dynamic responses and generated voltage in a curved sandwich beam with glass reinforced laminate(GRL)layers and a pliable core in the presence of a piezoelectric layer under low-velocity impact(LVI)are *** current study aims to carry out a dynamic analysis on the sandwich beam when the impactor hits the top face sheet with an initial *** the layer analysis,the high-order shear deformation theory(HSDT)and Frostig's second model for the displacement fields of the core layer are *** classical non-adhesive elastic contact theory and Hunter's principle are used to calculate the dynamic responses in terms of *** order to validate the analytical method,the outcomes of the current investigation are compared with those gained by the experimental tests carried out by other researchers for a rectangular composite plate subject to the *** element(FE)simulations are conducted by means of the ABAQUS *** effects of the parameters such as foam modulus,layer material,fiber angle,impactor mass,and its velocity on the generated voltage are reviewed.

关键词： analytical model piezoelectric layer curved sandwich beam glass reinforced laminate(GRL) pliable core low-velocity impact(LVI) classical non-adhesive elastic contact theory

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Modeling static friction behavior of elastic–plastic spherical adhesive microcontact in full-stick condition

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Friction 2024年第11期12卷 2594-2610页

作者： Guo XIANG Roman GOLTSBERG Izhak ETSION department of Mechanical engineering TechnionHaifa 32000Israel

The static friction behavior of an elastic–plastic spherical adhesive microcontact between a rigid flat and a deformable sphere under combined normal and tangential loading is studied by the finite element method(FEM).The contact between the sphere and the rigid flat is assumed to be full-stick,and the sliding inception is related to a loss of tangential *** intermolecular force between the rigid flat and the sphere is assessed by the Lennard–Jones(LJ)potential,which is applied to the sphere and the rigid flat by a user *** evolution of the adhesive force with tangential displacement in the full-stick condition is *** results indicate that the increasing effect of adhesive energy on the static friction coefficient gradually diminishes with an increase in the adhesive energy and the external normal ***,based on an extensive parametric study,an empirical dimensionless expression is obtained to predict the static friction coefficient of the spherical adhesive microcontact considering the intermolecular force.

关键词： adhesive spherical microcontact Lennard–Jones(LJ)potential elastic–plastic static friction

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Evolution of blockchain consensus algorithms: a review on the latest milestones of blockchain consensus algorithms

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Cybersecurity 2024年第3期7卷 80-101页

作者： Ziad Hussein May A.Salama Sahar A.El-Rahman Electrical engineering department Faculty of Engineering-ShoubraBenha UniversityCairoEgypt

Blockchain technology has gained widespread adoption in recent years due to its ability to enable secure and trans-parent record-keeping and data transfer.A critical aspect of blockchain technology is the use of consensus algorithms,which allow distributed nodes in the network to agree on the state of the *** this review paper,we exam-ine various consensus algorithms that are used in blockchain systems,including proof-of-work,proof-of-stake,and hybrid *** go over the trade-offs and factors to think about when choosing a consensus algorithm,such as energy efficiency,decentralization,and *** also look at the strengths and weaknesses of each algorithm as well as their potential impact on the scalability and adoption of blockchain technology.

关键词： Blockchain Consensus Proof of work Proof of stake Decentralization

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Studying the effect of surfactant assisted low-salinity water flooding on clay-rich sandstones

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Petroleum 2024年第2期10卷 306-318页

作者： Saeed Khezerloo-ye Aghdam Alireza Kazemi Mohammad Ahmadi department of Petroleum engineering Amirkabir University of Technology(AUT)TehranIran department of Petroleum and Chemical engineering College of EngineeringSultan Qaboos UniversityMuscatOman

Sandstone reservoirs often contain clay particles that can cause damage and reduce permeability during low-salinity water *** this study,the effect of surfactants on fine migration in clay-rich sandstones and its impact on oil recovery was ***,the impact of surfactants on interparticle forces in fine-matrix,fine-fine,and oil-matrix systems was *** results showed that both CTAB(cetyltrimethyl ammonium bromide)and QS(quillaja saponin)cause EDL compaction,weakening the repulsive ***,SDS(sodium dodecyl sulfate)and TX(triton X-100)do not affect the ***,the effect of surfactants on IFT reduction and wettability alteration was experimentally *** surfactants reduced IFT due to the surface excessive concentration *** wettability alteration experiment illustrated that although QS and CTAB compact EDL around oil and matrix particles leading to attraction force augmentation,they both alter wettability through adsorption on matrix and carboxylic groups present in crude oil,*** aqueous solutions were then injected into various clay-rich sandstone sanpacks,which resulted in increased oil ***,the mechanisms leading to enhanced oil recovery variedby surfactant *** increased recovery by 10%through IFT reduction and wettability alteration,while SDS and TX increased recovery by 12%and 9%,respectively,through wettability alteration and extreme fine *** contrast,partial fine migration in the QS flooding experiment reached a recovery increase of 18%.Permeability trends through experiments were also *** CTAB injection,permeability did not reduce,while QS aqueous solution reduced rock permeability to 5 m *** and TX reduced the magnitude of permeability to 2 m *** conclusion,this study demonstrates that surfactants can effectively improve oil recovery in clay-rich sandstones by altering the interparticle forces,reducing IFT,and changing *** results

关键词： Surfactant flooding Smart water Fine migration Recovery factor

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Note on Lower Triassic Gondolelloid Conodont Rediversifications with Emphasis on the Spathian Recovery

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Journal of Earth Science 2024年第4期35卷 1236-1242页

作者： Ali Murat Kilic department of Geological engineering Faculty of EngineeringBalikesir UniversityBalikesir99100Turkey

Conodonts,as a biotic group,next to ammonoids,pollen and spores,crustaceans and vertebrates,provide proxy clues for environment and age assessments of the rocks in which they *** are widely used for Triassic marine ***,there are various discussions about their multielement taxonomy and evolutionary lineages(e.g.,generation,speciation).Although first studies reported that most Triassic conodont species were unimembrate,studies carried out in the following years maintained that all Triassic conodonts were *** statistical reconstructions of a number of Triassic apparatuses were attempted,the discovery of fused clusters and natural assemblages has subsequently demonstrated that Triassic conodonts are indeed multimembrate,and all of the elements exist together in the same *** present paper aims to clarify the evolutionary relationship and array of some Lower Triassic *** dagisi *** described.

关键词： Triassic Spathian conodont Columbitella Siberia environmental geology

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High-resolution photogrammetry to measure physical aperture of two separated rock fracture surfaces

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Journal of Rock Mechanics and Geotechnical engineering 2024年第8期16卷 2922-2934页

作者： Masoud Torkan Mateusz Janiszewski Lauri Uotinen Alireza Baghbanan Mikael Rinne department of Civil engineering Aalto UniversityEspooFinland department of Mining engineering Isfahan University of TechnologyIsfahanIran

Photogrammetry,reconstructing three-dimensional(3D)models from overlapping two-dimensional(2D)photos,finds application in rock mechanics and rock engineering to extract geometrical details of reconstructed objects,for example rock *** properties are important for determining the mechanical stability,permeability,strength,and shear behavior of the rock *** can be used to reconstruct detailed 3D models of two separated rock fracture surfaces to characterize fracture roughness and physical aperture,which controls the fluid flow,hydromechanical and shear behavior of the rock *** research aimed to determine the optimal number of scale bars required to produce high-precision 3D models of a fracture surface.A workflow has been developed to define the physical aperture of a fracture using *** blocks of Kuru granite(25 cm×25 cm×10 cm)with an artificially induced fracture,were *** scaling 3D models,321 markers were used as ground control points(GCPs)with predefined distances on each *** the samples were wellmatched in their original positions,the entire block was *** data of the GCPs were extracted from the 3D model of the *** half was surveyed separately and georeferenced by GCPs and merged into the same coordinate *** fracture surfaces were extracted from the 3D models and the vertical distance between the two surfaces was digitally calculated as physical *** assessment of the photogrammetric reconstruction showed a 20-30 mm digital control distance accuracy when compared to known distances defined between *** attain this accuracy,the study found that at least 200 scale bars were ***,photogrammetry was employed to measure changes in aperture under normal *** results obtained from this approach were found to be in good agreement with those obtained using linear variable displacement transducers(LVDTs),with differences ran

关键词： Photogrammetry Physical aperture Rock fracture Predefined distances Markers

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