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Direct Detection of Explosives on solid surfaces by Mass spectrometry with Ambient Ion source Based on Dielectric Barrier Discharge

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Direct Detection of Explosives on Solid Surfaces by Mass Spe...

新方法研究头皮清洁后皮脂分泌和扩散的动力学过程

第三十五届国际光谱会议

作者： N.Na~1 S.C.Zhang~(1*) c.D.Yang~1 X.R.zhang~(1*) Department of chemistry Key Laboratory for Atomic and Molecular Nanosciences of the Education Ministry Tsinghua University Beijing 100084 china

＜正＞sensitive and specific detection of explosives is an important analytical issue,there is a high demand for developing highly sensitive methods for the real-time detection of explosives and explosive-related compounds with a low false alarm rate[1].Recently,a family of new ion source has been proposed allowing ions to be created under ambient conditions and then collected and analyzed by Ms,which are intended to be used for

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来源： cnki会议评论

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中华皮肤科杂志 2020年第6期53卷 490-491页

作者： Gao J Liu c zhang s L'Oréal Research & Innovation Pudong Shanghai China L'Oréal Research & Innovation Centre C. Zviak Saint-Ouen France

头皮上约有10万个毛囊不断将预先形成的皮脂转运至头皮表面,使日均分泌的皮脂总量维持在"克"的水平。先前的研究发现,与邻近的前额部皮肤相比,头皮的皮脂分泌率要低得多。尽管这两处皮脂的日常水平(scL,皮脂分泌平衡状态,单位μg/cm^2)... 详细信息

头皮上约有10万个毛囊不断将预先形成的皮脂转运至头皮表面,使日均分泌的皮脂总量维持在"克"的水平。先前的研究发现,与邻近的前额部皮肤相比,头皮的皮脂分泌率要低得多。尽管这两处皮脂的日常水平(scL,皮脂分泌平衡状态,单位μg/cm^2)相似,但其动力学有着很大差异:前额在清洁后3 h达到scL,而头皮则需要2~3 d。

关键词：额部皮肤皮脂分泌头皮平衡状态动力学过程新方法研究 scL

Three-dimensional interfacial fracture analysis of a one-dimensional hexagonal quasicrystal coating

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Applied Mathematics and Mechanics(English Edition) 2022年第12期43卷 1901-1920页

作者： Xin zhang Minghao ZHAO cuiying FAN c.s.LU Huayang DANG school of Mechanics and safety Engineering Zhengzhou UniversityZhengzhou 450001China school of Mechanical Engineering Zhengzhou UniversityZhengzhou 450001China school of civil and Mechanical Engineering Curtin UniversityWestern Australia6845Australia

In this paper, the three-dimensional(3D) interfacial fracture is analyzed in a one-dimensional(1D) hexagonal quasicrystal(Qc) coating structure under mechanical loading. A planar interface crack with arbitrary shape is studied by a displacement discontinuity method. Fundamental solutions of interfacial concentrated displacement discontinuities are obtained by the Hankel transform technique, and the corresponding boundary integral-differential equations are constructed with the superposition principle.Green’s functions of constant interfacial displacement discontinuities within a rectangular element are derived, and a boundary element method is proposed for numerical simulation.The singularity of stresses near the crack front is investigated, and the stress intensity factors(sIFs) as well as energy release rates(ERRs) are determined. Finally, relevant influencing factors on the fracture behavior are discussed.

关键词： one-dimensional(1D)hexagonal quasicrystal(Qc)coating displacement discontinuity method interface crack rectangular element stress intensity factor(sIF) energy release rate(ERR)

comparison of microstructure and mechanical behavior of Ti-35Nb manufactured by laser powder bed fusion from elemental powder mixture and prealloyed powder

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Journal of Materials science & Technology 2022年第10期105卷 1-16页

作者： J.c.Wang Y.J.Liu s.X.Liang Y.s.zhang L.Q.Wang T.B.sercombe L.c.zhang school of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA 6027Australia school of Engineering M050The University of Western Australia35 Stirling HighwayCrawleyPerthWA 6009Australia Northwest Institute for Nonferrous Metal Research Xi’an 710016China state Key Laboratory of Metal Matrix composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Although different types of powder feedstock are used for additive manufacturing via laser powder bed fusion(L-PBF),limited work has attempted to directly compare the microstructure and mechanical behavior of components manufactured from those powder feedstock.This work investigated the microstructure,phase composition,melt pool morphology,and mechanical properties of a prealloyed Ti-35Nb alloy manufactured using L-PBF and compared these to their counterparts produced from elemental powder mixture.The samples manufactured from the powder mixture are composed of randomly distributed undissolved Nb in theα/βmatrix,resulting from the unstable melt pool during the melting of the powder mixture.By contrast,parts produced from prealloyed powder display a homogeneous microstructure withβandαphases,owing to the full melting of prealloyed powder,therefore,a more stable melt pool to achieve a homogeneous microstructure.The Ti-35Nb manufactured from prealloyed powder exhibits large tensile ductility(about 10 times that of the counterparts using mixed powder),attributed to the high homogeneity in microstructure and chemical composition,strong interface bonding,relatively low oxygen content,and the existence of a large amount ofβphase.This work sheds insights into understanding the effect of powder feedstock on the melt pool stability therefore the microstructure and mechanical behavior of the resultant parts.

关键词： Titanium-niobium Powder bed fusion Additive manufacturing Melt pool stability Microstructure Mechanical properties

Tensile properties and deformation behavior of an extra-low interstitial fine-grained powder metallurgy near alpha titanium alloy by recycling coarse pre-alloyed powder

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Journal of Materials science & Technology 2022年第34期129卷 96-107页

作者： H.R.zhang H.Z.Niu M.c.Zang Y.H.zhang s.Liu D.L.zhang school of Materials science and Engineering Northeastern UniversityShenyang 110819China state Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China

An extra-low interstitial near alpha alloy Ti-3Al-2Zr-2Mo(wt%) was fabricated by hydrogenation and thermomechanical consolidation(TMc) of the coarse and spherical pre-alloyed powder with particle sizes of 60 to 270 μm. The coarse powder is a byproduct of pre-alloyed powder produced for selective laser and electron beam additive manufacturing. The TMc process involves powder compaction, fast sintering,in-situ dehydrogenation and an immediate hot extrusion to form a fully dense and fine-grained martensitic microstructure. Further dehydrogenation in vaccum at 700 °c converted the martensitic microstructure into an interwoven α/β microstructure which exhibited an improved yield strength, apparent necking and premature cracking at grain boundary α(α_(GB)) ribbons. A further annealing of 880 ℃/1 h/Ac led to the formation of a fine-grained α/β_(t)composite structure, which achieved an enhance ultimate tensile strength of 835 MPa and excellent tensile ductility of 16.0%. Analysis of the deformation behavior of the alloy in different states revealed that the α/β_(t)composite structures brought about an enhanced strain hardening capability by heterogeneous deformation effect of hard β_(t)and soft α-laths, which inhibited the formation of microcracks and consequently improved the coordinated deformation.

关键词： Nearα-Ti alloy coarse pre-alloyed powder Hydrogenation Tensile properties Deformation behaviour

cFD-based analysis of urban haze-fog dispersion—A preliminary study

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Building simulation 2021年第2期14卷 365-375页

作者： Yu zhang Yong Yu K.c.s.Kwok Feng Yan school of Medicine Tsinghua UniversityBeijingChina school of Aerospace Engineering Beijing Institute of TechnologyBeijingChina Faculty of Engineering School of Civil EngineeringThe University of SydneySydneyNew South WalesAustralia First Hospital of Tsinghua University BeijingChina

This paper proposes a computational fluid dynamics(cFD)model,along with dimensionless quantitative assessment standard—air pollution residual time(APRT)for the evaluation of local haze-fog(HF)dispersion in a built environment.A low APRT value ensures good ventilation.A building group model that comprises high-rise business building,mid-rise office buildings,low-mid-rise residential buildings(at the center of the building group),a mid-rise recreational center,and a local road(open terrain),was scaled down(1:100)to simulate the HF dispersion process.The orientation of the building group was numerically modified to generate a wind incidence normal to the high-rise building,mid-rise buildings,recreational center,and road.The results showed that the orientation of the building group largely determines the APRT.The most favorable orientation can reduce APRT by more than 50%.Our results strongly suggested that in order to reduce the consequential negative effect of air pollution,future urban designs should undergo a comprehensive ventilation assessment to ensure a low APRT value.

关键词： air pollution residual time urban environment high-rise building wind direction computational fluid dynamics

Major government customer and management earnings forecasts

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Frontiers of Business Research in china 2020年第3期14卷 350-369页

作者： Agnes c.s.cheng Wenli Huang shaojun zhang school of Accounting and Finance Faculty of BusinessThe Hong Kong Polytechnic UniversityHung HomKowloonHong KongChina

This paper examines whether customer base composition in the Us,that is,whether a firm's major customers are government entities or publicly traded companies,affects the properties of its management earnings forecasts(MEFs).Using a sample of 1,168 MEFs from 1998 to 2014,we find that firms whose major customers are government entities(i.e.,govemment suppliers)issue more precise and more accurate MEFs than firms whose major customers are public companies(i.e.,corporate suppliers).Moreover,when managers disclose negative information to the market,earnings forecasts issued by government suppliers have greater price impact than those issued by corporate suppliers.collectively,our empirical results suggest that having major govemment customers has a positive impact on the quality of MEFs.

关键词： customer-supplier relationship Demand uncertainty Government supplier Information spillover Management earnings forecasts(MEFs)

Distinct Electrical and Mechanical Responses of a cu-10Fe composite Prepared by Hot-Pressed sintering and Post Treatment

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Acta Metallurgica sinica(English Letters) 2024年第2期37卷 255-265页

作者： X.Y.Yue s.Y.Peng X.zhang c.N.He Y.Z.Tian Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China school of Materials science and Engineering and Tianjin Key Laboratory of composite and Functional Materials Tianjin UniversityTianjin300350China Research centre for Metallic Wires Northeastern UniversityShenyang110819China

A cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution treated.The hot-pressed sintered and solution treated materials were rolled and aged.The precipitation behavior and performance changes were systematically studied by using scanning electron microscopy and transmission electron microscopy.In contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the cu-10wt%Fe composite.The cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 K for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IAcs and softening temperature of 838 K.Mechanisms for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were analyzed.These findings provide a theoretical basis for designing high-performance cu-based in-situ composites by post treatment.

关键词： cu-Fe composite Hot-pressed sintering Thermal stability strength Electrical conductivity

Numerical modeling for a simulated rockburst experiment using Ls-DYNA

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Underground space 2021年第2期6卷 153-162页

作者： c.P.Yi E.Nordlund P.zhang s.Warema s.shirzadegan Division of Mining and Rock Mechanics Lulea University of TechnologySweden

Ground support systems are commonly used to mitigate the potential consequences of rockburst in burst prone mines.To assess the capacity of ground support systems when subjected to dynamic loading,simulated rockburst tests using blasting were conducted at the Kiruna Mine.In this study,a numerical simulation for one of the field tests was conducted using the Ls-DYNA code to investigate the dynamic response of the ground support systems including shotcrete and rockbolts.The numerical results showed a similar particle vibration pattern and a crack pattern to those of the field measurements.The effects of the detonator position and the charge configuration on the dynamic response of ground support systems are also discussed.Numerical results indicated that the peak particle vibrations on the tested panel increase along the direction of detonation propagation.It is difficult to use different charge concentrations in one borehole to investigate the effect of different dynamic loads on the dynamic response of support systems.Numerical results also indicated that 2D numerical modeling for simulated rockburst experiments could overestimate the dynamic response of ground support systems.

关键词： simulated rockburst experiments Ground support systems Numerical modeling