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Discovering the building blocks of atomic systems using machine learning:application to grain boundaries

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npj Computational Materials 2017年第1期3卷 212-218页

作者： Conrad w.Rosenbrock Eric R.Homer Gabor Csanyi gus l.w.hart Department of Physics and Astronomy Brigham Young UniversityProvoUT 84602USA Department of Mechanical Engineering Brigham Young UniversityProvoUT 84602USA Engineering laboratory University of CambridgeTrumpington StreetCambridge CB21PZUK

Machine learning has proven to be a valuable tool to approximate functions in high-dimensional ***,analysis of these models to extract the relevant physics is never as easy as applying machine learning to a large data set in the first *** we present a description of atomic systems that generates machine learning representations with a direct path to physical *** an example,we demonstrate its usefulness as a universal descriptor of grain boundary *** boundaries in crystalline materials are a quintessential example of a complex,high-dimensional system with broad impact on many physical properties including strength,ductility,corrosion resistance,crack resistance,and *** addition to modeling such properties,the method also provides insight into the physical“building blocks”that influence *** opens the way to discover the underlying physics behind behaviors by understanding which building blocks map to particular *** the structures are understood,they can then be optimized for desirable behaviors.

关键词： grain resistance corrosion

Machine-learned interatomic potentials for alloys and alloy phase diagrams

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npj Computational Materials 2021年第1期7卷 139-147页

作者： Conrad w.Rosenbrock Konstantin Gubaev Alexander VShapeev livia B.Pártay Noam Bernstein Gábor Csányi gus l.w.hart Department of Physics and Astronomy Brigham Young UniversityProvoUTUSA84602 Skolkovo Institute of Science and Technology Skolkovo Innovation CenterNobel Str.3Moscow 143026Russia Department of Chemistry University of ReadingWhiteknightsReading RG66ADUK Department of Chemistry University of WarwickCoventry CV47ALUK US Naval Research laboratory Center for Computational Materials ScienceWashingtonDC 20375USA Department of Engineering University of CambridgeTrumpington StreetCambridge CB21PZUK

we introduce machine-learned potentials for Ag-Pd to describe the energy of alloy configurations over a wide range of *** compare two different *** tensor potentials(MTPs)are polynomial-like functions of interatomic distances and *** Gaussian approximation potential(GAP)framework uses kernel regression,and we use the smooth overlap of atomic position(SOAP)representation of atomic neighborhoods that consist of a complete set of rotational and permutational invariants provided by the power spectrum of the spherical Fourier transform of the neighbor *** types of potentials give excellent accuracy for a wide range of compositions,competitive with the accuracy of cluster expansion,a benchmark for this *** both models are able to describe small deformations away from the lattice positions,SOAP-GAP excels at transferability as shown by sensible transformation paths between configurations,and MTP allows,due to its lower computational cost,the calculation of compositional phase *** the fact that both methods perform nearly as well as cluster expansion but yield off-lattice models,we expect them to open new avenues in computational materials modeling for alloys.

关键词： alloy alloys phase

Machine-learned multi-system surrogate models for materials prediction

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npj Computational Materials 2019年第1期5卷 702-707页

作者： Chandramouli Nyshadham Matthias Rupp Brayden Bekker Alexander V.Shapeev Tim Mueller Conrad w.Rosenbrock Gábor Csányi David w.wingate gus l.w.hart Department of Physics and Astronomy Brigham Young UniversityProvoUT 84602USA Fritz Haber Institute of the Max Planck Society Faradayweg 4–614195 BerlinGermany Skolkovo Institute of Science and Technology Skolkovo Innovation CenterBuilding 3Moscow 143026Russia Department of Materials Science and Engineering Johns Hopkins UniversityBaltimoreMD 21218USA Engineering laboratory University of CambridgeTrumpington StreetCambridge CB21PZUK Computer Science Department Brigham Young UniversityProvoUT 84602USA Citrine Informatics 702 Marshall StreetRedwood CityCA 94063USA

Surrogate machine-learning models are transforming computational materials science by predicting properties of materials with the accuracy of ab initio methods at a fraction of the computational *** demonstrate surrogate models that simultaneously interpolate energies of different materials on a dataset of 10 binary alloys(AgCu,AlFe,AlMg,AlNi,AlTi,CoNi,CuFe,CuNi,FeV,and NbNi)with 10 different species and all possible fcc,bcc,and hcp structures up to eight atoms in the unit cell,15,950 structures in *** find that the deviation of prediction errors when increasing the number of simultaneously modeled alloys isls representations and learning algorithms were found to qualitatively agree on the prediction errors of formation enthalpy with relative errors ofll systems.

关键词： alloys prediction CoNi

Petrogenesis, lA-ICP-MS zircon U-Pb geochronology and geodynamic implications of the Kribi metavolcanic rocks,Nyong Group, Congo craton

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Acta Geochimica 2022年第3期41卷 470-495页

作者： Hermine Mvodo Sylvestre Ganno gus Djibril Kouankap Nono Donald Hermann Fossi Philomene Estelle Nga Essomba Marvine Nzepang Tankwa Jean Paul Nzenti Department of Earth Sciences University of YaoundéIP.O.Box 812YaoundeCameroon Department of Geology HTTCUniversity of BamendaP.O.Box 39BambiliBamendaCameroon Institute for Geological and Mining Research P.O.Box 4110YaoundéCameroon Faculty of Mines and Petroleum Industries University of MarouaKaélé08MarouaCameroon

Metavolcanic rocks are well-exposed in the Kribi area within the Nyong Group, Congo craton, but their origin, age, and tectonic significance are poorly *** we report integrated field mapping and petrography,geochemistry, and lA-ICP-MS zircon U-Pb ages of these metavolcanic rocks to constrain their petrogenesis and geodynamic implications. The studied rocks consist of mafic granulite, garnet-amphibole gneiss, and garnet-biotite gneiss, and occur interbanded with sharp contact and intruded by syenite dyke. These metavolcanic rocks are classified as MORB-like tholeiitic to calc-alkaline basalts,basaltic andesite, and rhyodacite rocks with within-plate setting geochemical signatures. The metabasite rocks(basalt to basaltic andesite protolith) are likely the equivalent of a spinel peridotite product representing ~ 2–5 %partial melting of metasomatized mantle source, while the metarhyodacite rocks are derived from the fractional crystallization of the same parental magma. Zircon U-Pb data revealed that the rhyodacite rocks initially formed at2671 ± 51 Ma and underwent later metamorphism at2065 ± 55 Ma. The Neoarchean protolith age is comparable to the ca. 2628 Ma tholeiitic magmatism and ca.2666 Ma high-K granites, suggesting bimodal Neoarchean magmatic event within the Ntem Complex, while the metamorphic ages fall within the ca. 2100–2000 Ma highgrade tectono-metamorphic event attributed to Eburnean/Trans-Amazonian orogeny. At the regional scale,metavolcanic rocks with similar origins and ages are documented in the Sa o Francisco Craton in Brazil, suggesting comparable geodynamic evolution on both sides of the south Atlantic during the Paleoproterozoic.

关键词： Metavolcanic rocks MORB within plate volcanic zone Mantle source Fractional crystallization Congo craton Cameroon

laser additive manufacturing for infrastructure repair:A case study of a deteriorated steel bridge beam

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Journal of Materials Science & Technology 2023年第23期154卷 149-158页

作者： Shengbiao Zhang Peijun Hou Jiyun Kang Tianyi li Shahryar Mooraj Yang Ren Catherine H.Chen A.John hart Simos Gerasimidis wen Chen Department of Mechanical and Industrial Engineering University of Massachusetts Amherst MA 01003 USA Department of Civil and Environmental Engineering University of Massachusetts Amherst MA 01003 SA Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA X-ray Science Division Argonne National Laboratory Lemont IL 60439 USA Massachusetts Department of Transportation Boston MA 02116 USA Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA Department of Physics City University of Hong Kong Kowloon Hong Kong China

As our transportation infrastructure ages,its deterioration is becoming a growing *** and effective methods for repair can reduce the need for time-and cost-intensive replacement of structures such as roadway *** this work,laser-based additive manufacturing(AM)was developed for the repair of damaged beams in steel bridges.A corroded structural beam of low-carbon A36 steel was selected for this case study and 316l stainless steel was used for repair due to its excellent mechanical properties and corrosion *** repair experiments were performed on specimens extracted from the beam,and prepared with various groove shapes(Rectangular,Trapezoidal,and U-shaped).More in-depth parametric and microstructural studies were carried out with a series of U-shaped specimens repaired with the linear laser input energy varied from 19.5 to 30.0 J mm–*** tensile properties of the repaired specimens and interface structures were also investigated in *** was found that the repaired specimens had a slightly higher tensile strength despite a reduction in tensile elongation compared to the A36 steel base *** influence of interfacial microstructure and heterogeneity on the mechanical properties of the repaired specimens was *** work suggests the promising potential to employ AM for structural repair and provides fundamental insights into processing-structure-property relationships in laser AM-repaired materials.

关键词： Additive manufacturing Structural repair Mechanical properties Transportation infrastructure Dissimilar joint

Geochemistry and zircon U–Pb ages of the Paleoproterozoic ultramafic rocks of the Mbi Valley, Boali area, Central African Republic

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Acta Geochimica 2022年第3期41卷 515-535页

作者： Evine laure Njiosseu Tanko Prince Emilien Danguene Philomene Nga Essomba Tsoungui Sylvestre Ganno Jonas Didero Takodjou wambo Bertin Guy Takam Tchoupe gus Djibril Kouankap Nono Timoleon Ngnotue Boniface Kankeu Jean Biandja Jean Paul Nzenti Department of Earth Sciences University of DschangP.O.Box 67DschangCameroon Department of Earth Sciences University of BanguiP.O.Box 908BanguiCentral African Republic Department of Mining Engineering and Mineral Processing School of Mines and Petroleum IndustriesUniversity of MarouaP.O.Box 08Kaélé-MarouaCameroon Department of Earth Sciences University of YaoundéIP.O.Box 812YaoundéCameroon Department of Geology HTTCUniversity of BamendaP.O.Box 39BambiliBamendaCameroon Institute for Geological and Mining Researches(IGMR) P.O.Box 4110YaoundéCameroon

This paper investigates the geochemistry of bulk rock and infers the petrogenesis of ultramafic rocks in the Boali Precambrian terrane in Mbi Valley,in the North of the Central African Republic(CAR).The studied rocks comprise coarse primary olivine and orthopyroxene relics(dominant phase),magnesio-hornblende,magnetite,and ***-rock analysis indicates low SiO_(2)(average of 43.14 wt%)and high MgO(19.84–26.98 wt%)contents and their Mg number(Mg#)ranges from 74 to ***(526–865 ppm),Cr(1500–3680 ppm)***(Na_(2)O-K_(2)O)-FeO-MgO)and ACM(Al_(2)O_(3)-CaO-MgO)ternary diagrams have revealed that the studied samples correspond to arc-related ultramafic ***-normalized REE plots display an increasing trend from la to Sm(CeN/SmN:0.74–1.81),weak negative to no Eu(Eu/Eu*=0.72–1.05)and strong negative Ce(Ce/Ce*=0.33–0.98)*** mantle normalized of multi-element diagrams exhibit lREE enrichment and large ion lithophile elements(lIlE)relative to high field strength elements(HFSE),and notable negative anomalies in *** suggests the generation of the parent melt by slab dehydration and wedge melting *** addition,incompatible trace element composition and ratios assumed that the source magma had an enhanced mantle source associated with a prominent influence of continental *** of mantle wedge by plate-dehydrated,lIlE-rich fluids and the incorporation of sediments derived from subduction explain the enhancement of the *** major and trace element compositions jointly with the tectonic reconstruction of this region and lA-ICP-MS U–Pb data on zircon constrain the emplacement age at ca.2099 Ma in a continental margin arc setting involving subduction of an oceanic plate beneath the continental lithosphere,dehydration of the slab and mantle wedge *** result intimate that the remnants of Paleoproterozoic oceanic crust or subduction event and subsequent basins closure extended from

关键词： Atlantic supercontinent Central African Republic Ultramafic cumulate lIlE-enriched fluids Arc setting

Optoelectronic devices based on two-dimensional transition metal dichalcogenides

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Nano Research 2016年第6期9卷 1543-1560页

作者： He Tian Matthew l. Chin Sina Najmaei Qiushi Guo Fengnian Xia hart wang Madan Dubey Ming Hsieh Department of Electrical Engineering University of Southern California Los Angeles California 90089 USA United States Army Research laboratory Maryland 20783-1197 USA Department of Electrical Engineering Yale University Connecticut 06511 USA

In the past few years, two-dimensional （2D） transition metal dichalcogenide （TMDC） materials have attracted increasing attention of the research community, owing to their unique electronic and optical properties, ranging from the valley-spin coupling to the indirect-to-direct bandgap transition when scaling the materials from multi-layer to monolayer. These properties are appealing for the development of novel electronic and optoelectronic devices with important applications in the broad fields of communication, computation, and healthcare. One of the key features of the TMDC family is the indirect-to-direct bandgap transition that occurs when the material thickness decreases from multilayer to monolayer, which is favorable for many photonic applications. TMDCs have also demonstrated unprecedented flexibility and versatility for constructing a wide range of heterostructures with atomic-level control over their layer thickness that is also free of lattice mismatch issues. As a result, layered TMDCs in combination with other 2D materials have the potential for realizing novel high-performance optoelectronic devices over a broad operating spectral range. In this article, we review the recent progress in the synthesis of 2D TMDCs and optoelectronic devices research. we also discuss the challenges facing the scalable applications of the family of 2D materials and provide our perspective on the opportunities offered by these materials for future generations of nanophotonics technology.

关键词： transition metaldichalcogenides (TMDCs),optoelectronic device,molybdenum disulfide(MoS2) photodetector,light-emitting diode (lED)

Physical Characteristics Explain Ball-Carrying Capability in Sub-Elite Rugby Union Players

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Journal of Science in Sport and Exercise 2023年第3期5卷 244-253页

作者： Alexander S.hart Robert M.Erskine Tom J.Mclaughlin David R.Clark School of Sport and Exercise Science Liverpool John Moores UniversityL33AF LiverpoolUK Ealing Trailfinders Rugby Club LondonUK Institute of Sport Exercise and HealthUniversity College LondonLondonUK

Purpose The aims of the present study were two-fold:(i)to investigate the relationship between physical characteristics and the game statistics associated with ball-carrying capability amongst sub-elite rugby union players,and(ii)to predict the level of change in these physical characteristics required to improve the associated game statistic via regression *** Thirty-eight senior professional players(forwards,n=22;backs,n=16)were assessed for body mass(BM),back squat(BS)single-repetition maximum(1RM)normalised to BM(1RM/BM),10 m sprint velocity(S10),10 m sprint momentum(SM10),and the game statistics from 22 games within the 2019/20 RFU Championship *** relationship between these measures and the predicted level of change in a physical measure required to improve the total number of the associated game statistic by one were assessed by Pearson’s correlation coefficient and simple regression *** In forwards,an~11.5%reduction in BM,an~11.8%improvement in BS 1RM/BM,or an~11.5%increase in S10 was required to improve the game statistics associated with ball-carrying *** backs,a~19.3%increase in BM or a~15.6%improvement in SM10 was *** These findings demonstrate that improvements in lower-body relative strength,acceleration performance,and position-specific alterations in body mass are required to maximise the ball-carrying capability and therefore match outcome of sub-elite rugby union players.

关键词： Speed Acceleration Momentum Strength Body mass

livestock breeding for the 21st century: the promise of the editing revolution

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Frontiers of Agricultural Science and Engineering 2020年第2期7卷 129-135页

作者： Chris PROUDFOOT gus MCFARlANE Bruce wHITElAw Simon lIllICO The Roslin Institute and Royal(Dick)School of Veterinary Studies University of EdinburghEaster BushMidlothianEH259RGUK

In recent years there has been a veritable explosion in the use of genome editors to create sitespecific changes,both in vitro and in vivo,to the genomes of a multitude of species for both basic research and ***,which form a vital component of most societies,are no *** selective breeding has been hugely successful at enhancing some production traits,the rate of progress is often slow and is limited to variants that exist within the breeding *** editing provides the potential to move traits between breeds,in a single generation,with no impact on existing productivity or to develop de novo phenotypes that tackle intractable issues such as *** such,genome editors provide huge potential for ongoing livestock development programs in light of increased demand and disease *** review will highlight some of the more notable agricultural applications of this technology in livestock.

关键词： cattle pig sheep chicken aquaculture CRISPR