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Hydromechanical characterization of gas transport amidst uncertainty for underground nuclear explosion detection

Journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2019-2032页

作者： Wenfeng Li Chelsea W.Neil J William Carey Meng Meng Luke P.Frash Philip H.Stauffer Earth and Environmental Sciences Los Alamos National LaboratoryLos AlamosNM87544USA Department of Mineral Engineering New Mexico TechSocorroNM87801USA

Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radionuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the *** this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing *** testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty *** porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress *** Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3%±0.7%,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosity<1%,perhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous *** experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displacement;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be

关键词： Underground nuclear explosion uncertainty quantification Radionuclide transport Biot effective stress coefficient Fracture permeability Matrix permeability

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There might be two kinds of dibaryon

There might be two kinds of dibaryon

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第九届全国核物理大会

作者： T.Goldman Theoretical Division LANLLos AlamasNM87545USA

A systematic search ofdibaryons within the u,d,s three flavor world has been done with the quark delocalization and color screening model (QDCSM).The color screening effect due to q■ excitation and the quark delocalization caused by the mutual interaction of the interacting baryons have been included in the model Hamiltonian and model Hilbert space *** model parameters are constrained not only by the hadron spectroscopy

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Effects of heterofunctional alkali-metal formate doping on perovskite solar cell performance

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Journal of Materiomics 2022年第6期8卷 1165-1171页

作者： Sakshi Thakur Sung-Nam Kwon Dilpreet Singh Mann Seok-In Na Department of Flexible and Printable Electronics and lanl-JBNU Engineering Institute-Korea Jeonbuk National University567Baekje-daeroDeokjin-guJeonju-si54896Republic of Korea

Various internal and external defects present in the perovskite film are one of the main factors that causelow efficiency and stability, and in order to realize high-performance perovskite solar cells, it is necessaryto develop a method to effectively suppress them. In this study, a heterofunctional dopants strategy wasattempted to integrate the effect of alkali metal cations (Rbþ and Kþ) and formate anion (HCOO) throughdoping engineering with alkali-metal formates, i.e., rubidium formate (RbHCOO) and potassium formate(KHCOO). Inclusive physical and photoelectric analysis revealed that doping with a small amount ofalkali-metal formate leads to crystal growth and reduction of grain boundaries, and further passivates orinhibits bulk and surface defects. As a result, the photogenerated charge recombination was reduced andthe charge carrier transport was improved, leading to improved PSC performance. RbHCOO-dopedinverted planar PSCs achieved a PCE of up to 20.41% with long-term stability. Our findings provide away for producing high-quality perovskite films with low defect densities that are essential for realizinghigh-performance PSCs.

关键词： Perovskite solar cells Heterofunctional dopant Alkali-metal formate Rubidium formate Potassium formate Reduction of the charge trap density

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夸克蜕定域、色屏蔽和核力中程吸引

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科学通报 1993年第1期38卷 18-20页

作者：巫光汉滕礼坚王凡 T.Goldman 四川大学720研究所成都610064 南京大学物理系南京210008 lanl usa

我们曾在前文中提出一个新的QCD模型以处理重子相互作用。这模型的核心是夸克蜕定域和色屏蔽,前者有如分子物理中的分子轨道法,后者来自格点QCD计算。这模型得到了核力的中程吸引,实现了核子散射相移的定性符合。在通常夸克势模型中,重... 详细信息

我们曾在前文中提出一个新的QCD模型以处理重子相互作用。这模型的核心是夸克蜕定域和色屏蔽,前者有如分子物理中的分子轨道法,后者来自格点QCD计算。这模型得到了核力的中程吸引,实现了核子散射相移的定性符合。在通常夸克势模型中,重子中夸克波函数是s是重子势阱中心,b是这谐振子势阱的宽度参数。

关键词：蜕定域色屏蔽核力中程吸引夸克

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夸克蜕定域，色屏蔽和核中程吸引

夸克蜕定域，色屏蔽和核中程吸引

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第八届全国核物理会议

作者：巫光汉滕礼坚王凡 T.Goldman 四川大学南京大学 lanl usa

在通常核力的夸克势模型的基础上,我们加上：一、蜕定域;二、色屏蔽,得到了核力的中程吸引。一、蜕定域单夸克波函数取：

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Unsupervised phase mapping of X-ray diffraction data by nonnegative matrix factorization integrated with custom clustering

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npj Computational Materials 2018年第1期4卷 295-304页

作者： Valentin Stanev Velimir V.Vesselinov A.Gilad Kusne Graham Antoszewski Ichiro Takeuchi Boian S.Alexandrov Department of Materials Science and Engineering University of MarylandCollege ParkMD 20742USA Center for Nanophysics and Advanced Materials University of MarylandCollege ParkMD 20742USA Joint Quantum Institute University of MarylandCollege ParkMD 20742USA Los Alamos National Laboratory Earth Science DivisionLos AlamosNM 87545USA National Institute of Standards and Technology GaithersburgMD 20899USA Department of Mathematics University of MarylandCollege ParkMD 20742USA Los Alamos National Laboratory Theoretical DivisionLos AlamosNM 87545USA

Analyzing large X-ray diffraction(XRD)datasets is a key step in high-throughput mapping of the compositional phase diagrams of combinatorial materials *** and automating this task can help accelerate the process of discovery of materials with novel and desirable ***,we report a new method for pattern analysis and phase extraction of XRD *** method expands the Nonnegative Matrix Factorization method,which has been used previously to analyze such datasets,by combining it with custom clustering and cross-correlation *** new method is capable of robust determination of the number of basis patterns present in the data which,in turn,enables straightforward identification of any possible peak-shifted ***-shifting arises due to continuous change in the lattice constants as a function of composition and is ubiquitous in XRD datasets from composition spread *** identification of the peak-shifted patterns allows proper quantification and classification of the basis XRD patterns,which is necessary in order to decipher the contribution of each unique single-phase structure to the multi-phase *** process can be utilized to determine accurately the compositional phase diagram of a system under *** presented method is applied to one synthetic and one experimental dataset and demonstrates robust accuracy and identification abilities.

关键词： properties. phase nonnegative

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Surfactant Assisted Dispersion and Adhesion Behavior of Carbon Nanotubes on Cu—Zr and Cu—Zr—Al Amorphous Powders

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Journal of Materials Science & Technology 2014年第9期30卷 847-853页

作者： Jonathan Nguyen Haiming Wen Zhihui Zhang Frank Yaghmaie Enrique Lavernia Department of Chemical Engineering and Materials Science University of California at DavisDavis CA 95616 USA Northern California Nanotechnology Center University of California at DavisDavis CA 95616 USA

Carbon nanotubes （CNTs） were dispersed in gas atomized Cu47.5Zr47.5Al5 （CZA） and CusoZrso （CZ） amorphous powders, in an effort to elucidate the mechanisms of adhesion of CNTs onto amorphous metallic powders. CNTs were homogenously dispersed in water using a zwitterionic （ZW） surfactant. Then CZA and CZ powders were submersed in the ZW-CNTsuspensions with varying amounts of dwell time in an ultrasonic bath. The ZW-CNT- metal powder suspensions were dried, and CNT-metal composite powders were obtained after decomposition of the surfactant by calcination. Zeta potential measurements on ZW-CNT-metal powder suspensions and scanning electron microscopy investigation into the CNT-metal composite powders both indicated an ideal dwell time, for a specific alloy composition, of metallic powders in ZW-CNT suspension to achieve optimal adhesion of CNTs onto amorphous metallic powder surfaces. The results are rationalized on the basis of hydrolysis of metal ions into suspension creating a net positive charge on the metallic powder surfaces, and the interaction between the charged powder surfaces and the charged hydrophilic head groups of ZW, which has the other end attached to CNTs.

关键词： Metallic powders Carbon nanotubes Dispersion Surfactant Hydrolysis

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Sensitivity of the electronic and magnetic structures of cuprate superconductors to density functional approximations

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npj Computational Materials 2022年第1期8卷 266-276页

作者： Kanun Pokharel Christopher Lane James W.Furness Ruiqi Zhang Jinliang Ning Bernardo Barbiellini Robert SMarkiewicz Yubo Zhang Arun Bansil Jianwei Sun Department of Physics and Engineering Physics Tulane UniversityNew OrleansLA70118USA Theoretical Division Los Alamos National LaboratoryLos AlamosNM87545USA Center for Integrated Nanotechnologies Los Alamos National LaboratoryLos AlamosNM87545USA Department of Physics School of Engineering ScienceLUT UniversityFI-53851LappeenrantaFinland Physics Department Northeastern UniversityBostonMA02115USA

We discuss the crystal,electronic,and magnetic structures of La_(2−x)Sr_(x)CuO_(4)(LSCO)for x=0.0 and x=0.25 employing 13 density functional approximations,representing the local,semi-local,and hybrid exchange-correlation approximations within the Perdew–Schmidt *** meta-generalized gradient approximation(meta-GGA)class of functionals is found to perform well in capturing the key properties of LSCO,a prototypical high-temperature cuprate *** contrast,the localspin-density approximation,GGA,and the hybrid density functional fail to capture the metal-insulator transition under doping.

关键词： functional electronic approximation

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A high-throughput data analysis and materials discovery tool for strongly correlated materials

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npj Computational Materials 2018年第1期4卷 138-146页

作者： Hasnain Hafiz Adnan Ibne Khair Hongchul Choi Abdullah Mueen Arun Bansil Stephan Eidenbenz John Wills Jian-Xin Zhu Alexander V.Balatsky Towfiq Ahmed Department of Physics Northeastern UniversityBostonMA 02119USA Department of Computer Science University of New MexicoAlbuquerqueNM 87131USA Theoretical Division Los Alamos National LaboratoryLos AlamosNM 87545USA The Information Science and Technology Institute Los Alamos National LaboratoryLos AlamosNM 87545USA Nordita KTH Royal Institute of Technology and Stockholm UniversityRoslagstullsbacken 23Stockholm SE-10691Sweden Department of Physics University of ConnecticutStorrsCT 06269USA Department of Mechanical Engineering Carnegie Mellon UniversityPittsburghPA 15213USA

Modeling of f-electron systems is challenging due to the complex interplay of the effects of spin–orbit coupling,electron–electron interactions,and the hybridization of the localized f-electrons with itinerant conduction *** complexity drives not only the richness of electronic properties but also makes these materials suitable for diverse technological *** this context,we propose and implement a data-driven approach to aid the materials discovery *** deploying state-of-the-art algorithms and query tools,we train our learning models using a large,simulated dataset based on existing actinide and lanthanide *** machine-learned models so obtained can then be used to search for new classes of stable materials with desired electronic and physical *** discuss the basic structure of our f-electron database,and our approach towards cleaning and correcting the structure data *** examples of the applications of our database include successful prediction of stable superstructures of double perovskites and identification of a number of physically-relevant trends in strongly correlated features of f-electron based materials.

关键词： database desired conduction

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Broadband electroluminescence from reverse breakdown in individual suspended carbon nanotube pn-junctions

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Nano Research 2020年第10期13卷 2857-2861页

作者： Bo Wang Sisi Yang Yu Wang Younghee Kim Ragib Ahsan Rehan K.apadia Stephen KDoorn Han Htoon Stephen B.Cronin Department of Physics and Astronormy University of Southern CalforniaLos AngelesCA 90089USA Ming Hsieh Department of Electrical Engineering University of Southern CaliforniaLos AngelesCA 90089USA Mork Farmily Department of Chemical Engineering and Materials Science University of Southern CaliforniaLos AngelesCA 90089USA Center for Integrated Nanotechnologies Materials Physics and Applications DivisionLos Alamos National LaboratoryLos AlamosNM 87545USA

There are various mechanisms of light emission in carbon nanotubes (CNTs), which give rise to a wide range of spectral emission characteristics that provide important information regarding the underlying physical processes that lead to photon emission. Here, we report spectra obtained from individual suspended CNT dual-gate field effect transistor (FET) devices under different gate and bias conditions. By applying opposite voltages to the gate electrodes (i.e., Vg1 = –Vg2), we are able to create a pn-junction within the suspended region of the CNT. Under forward bias conditions, the spectra exhibit a peak corresponding to E11 exciton emission via thermal (i.e., blackbody) emission occurring at electrical powers around 8 μW, which corresponds to a power density of approximately 0.5 MW/cm2. On the other hand, the spectra observed under reverse bias correspond to impact ionization and avalanche emission, which occurs at electrical powers of ~ 10 nW and exhibits a featureless flat spectrum extending from 1,600 nm to shorter wavelengths up to 600 nm. Here, the hot electrons generated by the high electric fields (~ 0.5 MV/cm) are able to produce high energy photons far above the E11 (ground state) energy. It is somewhat surprising that these devices do not exhibit light emission by the annihilation of electrons and holes under forward bias, as in a light emitting diode (LED). Possible reasons for this are discussed, including Auger recombination.

关键词： ballistic avalanche high-field band-to-band photoemission

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