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Grain boundaries induce significant decrease in lattice thermal conductivity of CdTe

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能源与人工智能(英文) 2023年第1期11卷 43-50页

作者： Xiaona Huang Kun Luo Yidi Shen Yanan Yue Qi An School of Power and Mechanical Engineering Wuhan UniversityWuhanHubei 430072China Department of Chemical and Materials Engineering University of Nevada–RenoRenoNevada 89557United States Department of Materials Science and Engineering Iowa State UniversityAmesIA 50011United States

Semiconductors are promising in photoelectric and thermoelectric devices, for which the thermal transport properties are of particular interest. However, they have not been fully understood, especially when crystalline imperfections are present. Here, using cadmium telluride (CdTe) as an example, we illustrate how grain boundaries (GBs) affect the thermal transport properties of semiconductors. We develop a machine-learning force field from density functional theory calculations for predicting the lattice thermal conductivity (LTC) via equilibrium molecular dynamics simulations. The LTC of crystalline CdTe decreases with the relationship of κL~1/T in the simulation temperature range of 300 – 900 K, in which the isotropic LTC decreases from 3.34 to 0.23 W/ (m⋅K) due to the enhanced anharmonicity. More important, after introducing GBs, the LTC is suppressed in all directions, especially in the direction normal to the GB planes. More severe LTC suppression occurs in CdTe with Σ9 GB than that with Σ3 GB at 300 K, decreasing by 92.8% and 61.4% along the direction normal to the GB planes compared to the isotropic LTC of the crystalline CdTe, respectively. The decreased LTC is consistent with the weaker bonding near GB planes and lower shear modulus of the defective material. The analyses of the phonon dispersion curves, vibrational density of states, and phonon participation ratio indicate that the decreased LTC mainly arises from phonon scattering at GBs. Overall, our work highlights that GBs can greatly influence the LTC of semiconductors, thus providing a promising approach for thermal property design.

关键词： Lattice thermal conductivity Machine-learning force field Molecular dynamics CdTe Grain boundary

The role of crosswalk-related features on drivers' spatial yielding compliance at signalized midblock crosswalks

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Journal of Traffic and Transportation Engineering(English Edition) 2022年第4期9卷 666-675页

作者： Boniphace Kutela Texas A&M Transportation Institute College StationTX 77843USA

The drivers’yielding distance to pedestrians at midblock crosswalks affects pedestrians’perceived *** distance can be influenced by either crosswalk-related or *** most cases,crosswalk-related features are readily available or easy to collect compared to non-crosswalk ***,the extent to which crosswalk-related features affect the spatial yielding compliance is not *** study evaluated the role of combined crosswalk-related features on drivers’spatial yielding compliance at signalized midblock *** study used observational survey data collected from fifteen flash-based signalized midblock crosswalks located in Las Vegas,*** logistic regression models,with crosswalk-related features only,non-crosswalk features only,and combined features,were developed and *** was revealed that the performance difference between the model with crosswalk-related features only and combined features was *** study found that the presence of state’s law signs,“PED XING”signs,and placement of rectangular rapid flashing beacons(RRFBs)on the advanced pedestrians crossing signs(APCSs),are significant factors for high spatial yielding *** the contrary,the yield line’s presence at a distance greater than 40 ft from the crosswalk,presence of one stage crossing,and high Annual Average Daily Traffic(AADT)negatively affects the spatial yielding ***,the findings suggest that researchers should be careful about excluding the non-crosswalk features from the *** improve spatial yielding compliance,several recommendations that the city planners and engineers can adopt are provided.

关键词： Spatial yielding compliance Midblock crosswalks Pedestrians’safety Drivers’behavior

A molecular dynamics study of laser-excited gold

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Matter and Radiation at Extremes 2022年第3期7卷 20-30页

作者： Jacob M.Molina T.G.White university of nevada RenoNevada 89557USA

The structural evolution of laser-excited systems of gold has previously been measured through ultrafast MeV electron ***,there has been a long-standing inability of atomistic simulations to provide a consistent picture of the melting process,leading to large discrepancies between the predicted threshold energy density for complete melting,as well as the transition between heterogeneous and homogeneous *** make use of two-temperature classical molecular dynamics simulations utilizing three highly successful interatomic potentials and reproduce electron diffraction data presented by Mo et al.[Science 360,1451–1455(2018)].We recreate the experimental electron diffraction data,employing both a constant and temperature-dependent electron–ion equilibration *** all cases,we are able to match time-resolved electron diffraction data,and find consistency between atomistic simulations and experiments,only by allowing laser energy to be transported away from the interaction *** additional energy-loss pathway,which scales strongly with laser fluence,we attribute to hot electrons leaving the target on a timescale commensurate with melting。

关键词： diffraction. excited dynamics

Nanotwinning induced decreased lattice thermal conductivity of high temperature thermoelectric boron subphosphide (B12P2) from deep learning potential simulations

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能源与人工智能(英文) 2022年第2期8卷 5-12页

作者： Xiaona Huang Yidi Shen Qi An School of Power and Mechanical Engineering Wuhan UniversityWuhanHubei430072China Department of Chemical and Materials Engineering University of Nevada-RenoRenoNevada89557United States of America

Boron subphosphide(B_(12)P_(2))is a promising high temperature thermoelectric material due to its good thermal stability,and chemical ***,the thermal properties of B_(12)P_(2) have not been well revealed so ***,we first develop a deep learning potential for B_(12)P_(2) based on quantum mechanical *** the isotropic lattice thermal conductivity(LTC)of crystalline B_(12)P_(2) is predicted to be 39.70±4.38 W/m⋅K from molecular dynamics simulations using this deep learning *** LTC exhibits the relationship ofκL~1/T in the temperature range of 300~1500 *** important,a twin boundary strategy is proposed to reduce the LTC of B_(12)P_(2).In nanotwinned B_(12)P_(2),the phonon transport in all directions is significantly suppressed by twin boundaries(TBs)with the isotropic LTC of 15.85±2.70 W/m⋅K,especially in the direction normal to the TB *** decrease of vibrational density of states and phonon participation ratio due to TBs’phonon scattering is the main reason of the low LTC in nanotwinned B_(12)P_(2).In addition,the elastic moduli(B and G)of B_(12)P_(2) crystal decrease by less than 7%after inducing TBs,which suggests that the mechanical properties are not significantly affected by ***,this work enriches our understanding of the thermal properties of B_(12)P_(2) and offers a promising approach,i.e.,introducing TBs,to design high-performance thermoelectric materials.

关键词： Nanotwinned B_(12)P_(2) Lattice thermal conductivity High temperature thermoelectric material Deep learning potential

Texture evaluation in AZ31/AZ31 multilayer and AZ31/AA5068 laminar composite during accumulative roll bonding

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Defence Technology（防务技术） 2020年第3期16卷 514-519页

作者： Pankaj Kumar Aviral Madhup Prasad RKalvala Satyam Suwas Chemical and Materials Engineering University of NevadaRenoNV89557USA Materials Engineering Indian Institute of ScienceBangalore560012India

This article presents the texture development of magnesium AZ31 alloy in the accumulative roll bonded(ARB) AZ31/AZ31 multilayer and AZ31/AA5086 laminate *** comparative study demonstrates that the texture evolution in AZ31 in a multilayer system is strongly influenced by the interfaces.A typical basal texture of AZ31 has been observed in AZ31/AZ31 multilayer with texture intensity increased with the rolling *** of AZ31/AA5086 interface in the laminate composite leads to a tilted basal texture along the rolling direction(RD) in AZ31 *** texture intensity of composite increased initially with rolling reduction and weakened at the higher rolling *** of texture in AZ31 during the laminate processing at higher strain has been attributed to the development of wavy interfaces in AZ31/AA5086 laminate.

关键词： Accumulative roll bonding Defence application AZ31 alloy Texture Composite Laminates

Genomic surveillance of nevada patients revealed prevalence of unique SARS-CoV-2 variants bearing mutations in the RdRp gene

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Journal of Genetics and Genomics 2021年第1期48卷 40-51页

作者： Paul D.Hartley Richard L.Tillett David P.AuCoin Joel R.Sevinsky Yanji Xu Andrew Gorzalski Mark Pandori Erin Buttery Holly Hansen Michael A.Picker Cyprian C.Rossetto Subhash C.Verma nevada Genomics Center RenoNV 89557USA university of nevada RenoRenoNV 89557USA nevada Institute of Personalized Medicine University of NevadaLas VegasNV 89154USA Department of Microbiology&Immunology University of NevadaReno School of MedicineRenoNV 89557USA Theiagen Consulting LLCHighlands RanchCO 80128USA nevada Center for Bioinformatics RenoNV 89557USA nevada State Public Health Laboratory RenoNV 89503USA Southern nevada Public Health Laboratory of the Southern nevada Health District Las VegasNV 89107USA

Patients with signs of COVID-19 were tested through diagnostic RT-PCR for SARS-CoV-2 using RNA extracted from the nasopharyngeal/nasal *** determine the variants of SARS-CoV-2 circulating in the state of nevada,specimens from 200 COVID-19 patients were sequenced through our robust sequencing platform,which enabled sequencing of SARS-CoV-2 from specimens with even very low viral loads,without the need of culture-based *** genome coverage allowed the identification of single and multi-nucleotide variants in SARS-CoV-2 in the community and their phylogenetic relationships with other variants present during the same period of the *** report the occurrence of a novel mutation at 323aa (314aa of orf1b) of nsp12 (RNA-dependent RNA polymerase) changed to phenylalanine(F) from proline (P),in the first reported isolate of SARS-CoV-2,*** 323F variant was present at a very high frequency in Northern *** modeling determined this mutation in the interface domain,which is important for the association of accessory proteins required for the *** conclusion,we report the introduction of specific SARS-CoV-2 variants at very high frequency in distinct geographic locations,which is important for understanding the evolution and circulation of SARS-CoV-2variants of public health importance,while it circulates in humans.

关键词： SARS-CoV-2 COVID-19 Genome enrichment nsp12 RdRp orf1b 314

Fe-Ti oxide mineralization in the XV intrusion， Bafq mining district， Central Iran: insights from mineralogy， mineral chemistry and S isotopic data

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Journal of Earth Science 2022年

作者： Sakine Amraei Majid Ghasemi Siani Mohammad Yazdi Liang Qiu Bertrand Moine Minghua Ren Department of Inorganic Geology and Water， Faculty of Earth Sciences， Shahid Beheshti university Department of Geochemistry， Faculty of Earth Sciences， Kharazmi university State Key Laboratory of Geological Processes and Mineral Resources， School of Earth Sciences and Resources， China university of Geosciences Université Clermont Auvergne， CNRS， IRD， OPGC， Laboratoire Magmas et Volcans Department of Geoscience， university of nevada Las Vegas

The mafic-ultramafic intrusion in the XV anomaly area， which contains magmatic Fe-Ti oxide-（P） ore， is located in the Bafq mining district in the Central Iran. It consists of cumulate and layered Fe-Ti-bearing gabbros and pyroxenites. The mineral assemblages include clinopyroxene， Fe-Ti oxides， plagioclase， amphibole， apatite and sulfides （pyrite and chalcopyrite）. The Fe-Ti oxides mainly consist of magnetite-titanomagnetite and ilmenite， which occur as disseminated， intergrowth， lamellae （trellis and sandwich textures） and inclusions. Magnetite in the gabbroic rocks is from the near end-member of Fe;O;(<1 wt.% TiO;) to titanomagnetite containing up to 8 wt.% TiO;(about 3.73% to 26.84% Ulvospinel (X;)). Magnetite in pyroxenite rocks is characterized with TiO;range from 0.46 to 3.14 wt.% (X;varied from 1.76% to 10.46%). The abundances of V;O;range from 0.03 to 1.29 and 0.24 to 1.00 wt.% for gabbro and pyroxenite， respectively. X;contents of magnetite show insignificant correlations with Al;O;and MgO. The average X;in the ilmenite of gabbro is 92%， whereas it is 90.37% in the pyroxenite rocks. The MgO and V;O;contents show a slightly positive correlation with TiO;in ilmenite. The composition of clinopyroxenes in gabbro and pyroxenite rocks fall in the diopside to augite field with Mg# ranging from 67 to 98 and 74 to 96， respectively. In both rock types， amphiboles are mainly pargasite and rarely actinolite. Plagioclase in pyroxenite rocks are clustered in the labradorite to andesine fields with a compositional ranges of An;and in gabboic rocks fall in two fields with compositional ranges of albite with An;and labradorite with An;. The δ;S isotopic values cover a limited range from +3.15‰ to +4.10‰ V-CDT consistent with magmatic origin. Fe-Ti mineralization are formed in two stages， minor inclusions of Fe–Ti oxide minerals in the pyroxene and plagioclase crystallized in the early magmatic stage， whereas interstitial oxides formed by fractional crystallization processes

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Computational studies on the seismic response of the State Route 99 bridge in Seattle with SMA/ECC plastic hinges

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 149-164页

作者： Jiping GE M.Saiid SAIIDI Sebastian VARELA School of Urban Construction and Safety Engineering Shanghai Institute of TechnologyShanghai 201418China Department of Civil and Environmental Engineering University of NevadaRenoNV 89557USA Structural Engineering Group Freese and Nichols Inc.Fort WorthTX 76109USA

This paper reports a computational study on the seismic response of a three-span highway bridge system incorporating conventional and novel substructure details for improved seismic *** bridge has three continuous spans supported by two single-column piers and integral abutments founded on drilled *** will be the first full-scale highway bridge to use superelastic shape memory alloy bars (SMA)and engineered cementitious composite (ECC)to mitigate column plastic hinge damage and minimize residual displacements after a strong earthquake. A three-dimensional computational model capturing the nonlinear constitutive response of the novel materials and the effects of dynamic soil-structure interaction was developed to assess the seismic response of the bridge in finite-element software *** versions of the same bridge were analyzed and compared,one with conventional cast-in-place reinforced concrete columns,and the other with top plastic hinges incorporating Nickel-Titanium (NiTi)SMA reinforcing bars and *** novel SMA/ECC plastic hinges were found to substantially reduce damage and post-earthquake residual displacements in the bridge substructure,but led to larger maximum drifts relative to the bridge with conventional reinforced concrete plastic *** analysis results suggested that the novel plastic hinges could lead to improved post-earthquake serviceability of bridges after intense earthquakes.

关键词： seismic design analytical simulation near-fault earthquakes shape memory alloy engineered cementitious composite self-centering

Simulation and animation model to boost mining efficiency and enviro-friendly in multi-pit operations

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International Journal of Mining Science and Technology 2015年第4期25卷 671-674页

作者： Tarshizi Ebrahim Sturgul John Ibarra Virginia Taylor Danny Mining & Metallurgical Engineering Department University of Nevada Reno School of Civil Environmental and Mining Engineering University of Adelaide

A discrete-event system simulation and animation program was developed to enhance the efficiency of a truck-excavator operation and reduce the environmental impact of haulage in an open-cut coal mine with multiple-pit operations. In any mine, a key objective is to have sufficient equipment for production and not to have excess to where it becomes counterproductive. Due to the advent of responsible mining,environmental regulations, and eco-friendly practices, these factors must also be considered in the analysis. Simulation studies can be financially advantageous for both the optimization of existing mine operations and new development phases in a mine. This study is a new approach to use discrete-event system simulation for mine systems, in order to investigate and possibly reduce environmental impact considering mining haulage performance and production target. A hypothetical layout of a surface coal mine with two pit operations was used for the simulation and animation model. The simulation model includes the animation of the operation. Animation is helpful to enhance the benefit of a mine simulation model. GPSS/Hòand Proof Professionalòwere the software used for the investigation.

关键词：离散事件系统仿真动画模型环境友好挖掘机操作矿井作业生态环境保护生产设备