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Laser-induced breakdown spectroscopy as a method for millimeter-scale inspection of surface flatness
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作者 Jinrui YE Yaju LI +8 位作者 Zhao ZHANG Xinwei WANG Kewei TAO Qiang ZENG Liangwen CHEN Dongbin QIAN Shaofeng ZHANG Lei YANG Xinwen MA 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第9期148-155,共8页
A non-contact method for millimeter-scale inspection of material surface flatness via Laser-Induced Breakdown Spectroscopy(LIBS)is investigated experimentally.The experiment is performed using a planished surface of a... A non-contact method for millimeter-scale inspection of material surface flatness via Laser-Induced Breakdown Spectroscopy(LIBS)is investigated experimentally.The experiment is performed using a planished surface of an alloy steel sample to simulate its various flatness,ranging from 0 to 4.4 mm,by adjusting the laser focal plane to the surface distance with a step length of 0.2 mm.It is found that LIBS measurements are successful in inspecting the flatness differences among these simulated cases,implying that the method investigated here is feasible.It is also found that,for achieving the inspection of surface flatness within such a wide range,when univariate analysis is applied,a piecewise calibration model must be constructed.This is due to the complex dependence of plasma formation conditions on the surface flatness,which inevitably complicates the inspection procedure.To solve the problem,a multivariate analysis with the help of Back-Propagation Neural Network(BPNN)algorithms is applied to further construct the calibration model.By detailed analysis of the model performance,we demonstrate that a unified calibration model can be well established based on BPNN algorithms for unambiguous millimeter-scale range inspection of surface flatness with a resolution of about 0.2 mm. 展开更多
关键词 laser-induced breakdown spectroscopy machine learning surface flatness
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Study of corrective abrasive finishing for plane surfaces using magnetic abrasive finishing processes 被引量:2
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作者 Yulong Zhang Yanhua Zou 《Nanotechnology and Precision Engineering》 CAS CSCD 2021年第3期1-11,共11页
On the basis of ordinary plane magnetic abrasive finishing,a finishing method is proposed that can improve the flatness of a plane workpiece.In this method,the feed speed is varied during finishing according to the pr... On the basis of ordinary plane magnetic abrasive finishing,a finishing method is proposed that can improve the flatness of a plane workpiece.In this method,the feed speed is varied during finishing according to the profile curve of the initial surface and the material removal efficiency,to control the effective finishing time in different areas and thereby improve the surface flatness.A small magnetic pole with an end face diameter of 1 mm is designed,and a ferromagnetic plate is placed under the workpiece to improve the uniformity of the magnetic field distribution near the magnetic pole.An experiment on an A5052 aluminum alloy plate workpiece shows that after 60 min of finishing using the proposed method,the extreme difference of the workpiece surface can be reduced from 14.317μm to 2.18μm,and the standard deviation can be reduced from 3.322μm to 0.417μm.At the same time,according to the measurement results,a similar flatness can be achieved at different positions on the finishing area.Thus,the proposed variable-speed finishing method leads to obvious improvements in flatness. 展开更多
关键词 Variable speed Magnetic abrasive finishing Corrective abrasive finishing Finishing efficiency surface flatness Aluminum alloy(A5052)
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Surface Majorana flat bands in j=3/2 superconductors with singlet-quintet mixing
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作者 Jiabin Yu Chao-Xing Liu 《Chinese Physics B》 SCIE EI CAS CSCD 2020年第1期430-445,共16页
Recent experiments[Science Advances 4 eaao4513(2018)]have revealed the evidence of nodal-line superconductivity in half-Heusler superconductors,e.g.,YPt Bi.Theories have suggested the topological nature of such nodal-... Recent experiments[Science Advances 4 eaao4513(2018)]have revealed the evidence of nodal-line superconductivity in half-Heusler superconductors,e.g.,YPt Bi.Theories have suggested the topological nature of such nodal-line superconductivity and proposed the existence of surface Majorana flat bands on the(111)surface of half-Heusler superconductors.Due to the divergent density of states of the surface Majorana flat bands,the surface order parameter and the surface impurity play essential roles in determining the surface properties.We study the effect of the surface order parameter and the surface impurity on the surface Majorana flat bands of half-Heusler superconductors based on the Luttinger model.To be specific,we consider the topological nodal-line superconducting phase induced by the singlet-quintet pairing mixing,classify all the possible translationally invariant order parameters for the surface states according to irreducible representations of C3vpoint group,and demonstrate that any energetically favorable order parameter needs to break the time-reversal symmetry.We further discuss the energy splitting in the energy spectrum of surface Majorana flat bands induced by different order parameters and non-magnetic or magnetic impurities.We propose that the splitting in the energy spectrum can serve as the fingerprint of the pairing symmetry and mean-field order parameters.Our theoretical prediction can be examined in the future scanning tunneling microscopy experiments. 展开更多
关键词 surface Majorana flat band half-Heusler superconductor
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High-quality micro-shape fabrication of monocrystalline diamond by nanosecond pulsed laser and acid cleaning 被引量:1
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作者 Yasuhiro Okamoto Tubasa Okubo +1 位作者 Atsuya Kajitani Akira Okada 《International Journal of Extreme Manufacturing》 SCIE EI 2022年第2期173-183,共11页
The flat plane of small surface roughness below 0.1μm average roughness was obtained for monocrystalline diamond by nanosecond pulsed laser irradiation of 1060 nm and post-process acid cleaning,at a laser fluence aro... The flat plane of small surface roughness below 0.1μm average roughness was obtained for monocrystalline diamond by nanosecond pulsed laser irradiation of 1060 nm and post-process acid cleaning,at a laser fluence around the material removal threshold value.The glossy and flat plane at the bottom of the micro-groove was parallel to the top surface of the specimen,although the round beam of Gaussian mode was irradiated in the direction perpendicular to the top surface of specimen.The square beam of top-hat mode produced a shallower micro-groove with a wider,flatter bottom compared with the round beam in Gaussian mode.The creation method of the flat plane with small surface roughness was discussed in the arrangement strategy of linear micro-grooving by the square beam of top-hat mode.Normal side-by-side repetition of linear micro-grooving did not create a flat plane with constant depth.Therefore,a two-step scanning method was proposed in order to overcome the problem in the normal side-by-side repetition of liner micro-grooving.Non-removal areas were partly retained between the processing lines in the first step,and the laser scanning was conducted on the retained area in the second step.The newly proposed two-step scanning method was practical and useful to create a widely flat plane with small surface roughness,and the two-step scanning method provided superior control over the micro-groove depth.This proposed method can reduce the surface roughness in addition to the shape creation of monocrystalline diamond,and it can be used as a high-quality micro-shape fabrication method of monocrystalline diamond. 展开更多
关键词 monocrystalline diamond nanosecond pulsed laser flat surface smooth surface micro-grooving
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ON MINIMAL IMMERSIONS OF R^2 INTO THE NEARLY KAHLER S^6
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作者 沈一兵 贺群 《Acta Mathematica Scientia》 SCIE CSCD 2004年第3期349-360,共12页
In terms of the almost complex affine connection and moving unitary frames, all totally rael minimal immersions from R-2 into the nearly Kahler S-6 axe determine explicitly. Moreover, the complete flat almost complex ... In terms of the almost complex affine connection and moving unitary frames, all totally rael minimal immersions from R-2 into the nearly Kahler S-6 axe determine explicitly. Moreover, the complete flat almost complex curves in the nearly Kahler S-6 are determined completely. 展开更多
关键词 minimal immersion the nearly Kahler S-6 flat totally real surface
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Particulate Matter Exposure of Rural Interior Communities as Observed by the First Tribal Air Quality Network in the Yukon Flat
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作者 Stanley G.Edwin Nicole Molders 《Journal of Environmental Protection》 2018年第13期1425-1448,共24页
A tribal-owned network of aerosol monitors and meteorological stations was installed at Ts’aahudaaneekk’onh Denh (Beaver), Gwichyaa Zheh (Fort Yukon), Jalgiitsik (Chalkyitsik), and Danzhit Khànlaii (Circle) in ... A tribal-owned network of aerosol monitors and meteorological stations was installed at Ts’aahudaaneekk’onh Denh (Beaver), Gwichyaa Zheh (Fort Yukon), Jalgiitsik (Chalkyitsik), and Danzhit Khànlaii (Circle) in the Yukon Flats, Alaska. Surface inversions occurred under calm wind conditions due to radiative cooling. In May, local emissions governed air quality with worst conditions related to road and river dust. As the warm season progressed, worst air quality was due to transport of pollutants from upwind wildfires. During situations without smoke or when smoke existed at layers above the surface inversion, concentrations of particulate matter of less than 2.5 micrometer in diameter or less (PM2.5) were explainable by the local emissions;24-h means remained below 25 μg·m-3. Absorption of solar radiation in the smoke layer and upward scattering enhanced stability and fostered the persistence of the surface inversions. During smoke episodes without the presence of a surface inversion, daily mean concentrations exceeded 35 μg·m-3 often for several consecutive days, at all sites. Then concentrations temporally reached levels considered unhealthy. 展开更多
关键词 Summer surface Inversions in the Yukon Flats PM_(2.5) Concentrations in Rural Alaska Villages First Tribal Air-Quality Network in the Yukon Flats
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Development and test of a multifactorial parameterization scheme of land surface aerodynamic roughness length for flat land surfaces with short vegetation 被引量:3
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作者 ZHANG Qiang YAO Tong YUE Ping 《Science China Earth Sciences》 SCIE EI CAS CSCD 2016年第2期281-295,共15页
Aerodynamic roughness length is an important physical parameter in atmospheric numerical models and microme- teorological calculations, the accuracy of which can affect numerical model performance and the level of mic... Aerodynamic roughness length is an important physical parameter in atmospheric numerical models and microme- teorological calculations, the accuracy of which can affect numerical model performance and the level of micrometeorological computations. Many factors influence the aerodynamic roughness length, but formulas for its parameterization often only con- sider the action of a single factor. This limits their adaptive capacity and often introduces considerable errors in the estimation of land surface momentum flux (friction velocity). In this study, based on research into the parameterization relations between aerodynamic roughness length and influencing factors such as windrow conditions, thermodynamic characteristics of the sur- face layer, natural rhythm of vegetation growth, ecological effects of interannual fluctuations of precipitation, and vegetation type, an aerodynamic roughness length parameterization scheme was established. This considers almost all the factors that af- fect aerodynamic roughness length on flat land surfaces with short vegetation. Furthermore, using many years' data recorded at the Semi-Arid Climate and Environment Observatory of Lanzhou University, a comparative analysis of the application of the proposed parameterization scheme and other experimental schemes was performed. It was found that the error in the friction velocity estimated by the proposed parameterization scheme was considerably less than that estimated using a constant aero- dynamic roughness length and by the other parameterization schemes. Compared with the friction velocity estimated using a constant aerodynamic roughness length, the correlation coefficient with the observed friction velocity increased from 0.752 to 0.937, and the standard deviation and deviation decreased by about 20% and 80%, respectively. Its mean value differed from the observed value by only 0.004 m s-l and the relative error was only about 1.6%, which indicates a significant decrease in the estimation error of surface-layer momentum flux. The test results show that the multifactorial universal parameterization scheme of aerodynamic roughness length for flat land surfaces with short vegetation can offer a more scientific parameteriza- tion scheme for numerical atmospheric models. 展开更多
关键词 Flat land surface with short vegetation Multifactorial influence Aerodynamic roughness length Parameterizationscheme Friction velocity
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Convective heat transfer on flat and concave surfaces subjected to an impinging jet form lobed nozzle 被引量:1
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作者 LYU YuanWei ZHANG JingZhou +1 位作者 WANG BoYan TAN XiaoMing 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2020年第1期116-127,共12页
A tri-dimensional lobed nozzle is concerned in the jet impingement on a flat target and a concave target in the current study. The jet impingement heat transfer experiments are conducted under two jet Reynolds numbers... A tri-dimensional lobed nozzle is concerned in the jet impingement on a flat target and a concave target in the current study. The jet impingement heat transfer experiments are conducted under two jet Reynolds numbers(Re=10000 and 20000) and four nozzle-to-surface distances(H/d=2, 4, 6 and 8). Simultaneously, to characterize the flow dynamics of lobed jet impingement onto different target surfaces, some computations are conducted under a specific jet Reynolds number. The results show that the lobed jet is capable of achieving an increase of stagnation Nusselt number about 25% in relative to the round jet at small nozzle-tosurface distances. However, at large nozzle-to-surface distances, the lobed jet otherwise weakens the convective heat transfer in the vicinity of jet stagnation, especially under high jet Reynolds number. When compared to the flat target, approximately a20%–30% reduction of stagnation Nusselt number is produced on a concave target, which is attributed to the combined effect of destabilization and confinement due to the concave curvature. 展开更多
关键词 jet impingement enhanced heat transfer lobed nozzle flat surface concave surface
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Absolute surface form measurement of flat optics based on oblique incidence method 被引量:1
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作者 Longbo Xu Shijie Liu +2 位作者 Rihong Zhu You Zhou Jie Chen 《Chinese Optics Letters》 SCIE EI CAS CSCD 2018年第10期30-33,共4页
In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a ... In this Letter, a test method based on oblique incidence is practically implemented in the interferometric measurement process. Three sets of wavefront data are achieved through cavity interference measurement with a Fizeau interferometer and one oblique incidence measurement. An iterative algorithm is applied to retrieve the absolute surface shape of the test flat. By adding two sets of measurements, the absolute surface error of the interferometer's reference flat can be obtained. The new method can not only calibrate the reference flat error of interferometer, but also provide the absolute measurement method for high precision optical components applied in high power laser systems. 展开更多
关键词 Absolute surface form measurement of flat optics based on oblique incidence method
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Classification of Flat Lagrangian Surfaces in Complex Lorentzian Plane
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作者 Bang-Yen CHEN Johan FASTENAKELS 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2007年第12期2111-2144,共34页
One of the most fundamental problems in the study of Lagrangian submanifolds from Riemannian geometric point of view is to classify Lagrangian immersions of real space forms into complex space forms. The main purpose ... One of the most fundamental problems in the study of Lagrangian submanifolds from Riemannian geometric point of view is to classify Lagrangian immersions of real space forms into complex space forms. The main purpose of this paper is thus to classify flat Lagrangian surfaces in the Lorentzian complex plane C1^2. Our main result states that there are thirty-eight families of flat Lagrangian surfaces in C1^2. Conversely, every flat Lagrangian surface in C1^2 is locally congruent to one of the thirty-eight families. 展开更多
关键词 flat Lagrangian surfaces Lorentzian complex plane Legendre curve
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Improvement of Raman spectrum uniformity of SERS substrate based on flat electrode
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作者 江志辉 张申 +4 位作者 宋从喜 毛红敏 赵鑫 陆焕钧 曹召良 《Chinese Optics Letters》 SCIE EI CAS CSCD 2023年第11期128-135,共8页
The distribution of metal nanoparticles on the surface of a surface enhancement Raman scattering(SERS)-active substrate plays a prominent part in not only the enhancement of Raman vibration signal,but also the spectru... The distribution of metal nanoparticles on the surface of a surface enhancement Raman scattering(SERS)-active substrate plays a prominent part in not only the enhancement of Raman vibration signal,but also the spectrum uniformity.Here,a facile method to fabricate SERS substrates with excellent homogeneity and low cost was proposed,in which a lyotropic liquid crystal soft template was introduced for the coordinated growth of the silver nanoflowers in the process of electrochemistry deposition.Simulation was carried out to illustrate the dominated influence of the distance of electrodes on the deposited nanoparticle number.Two kinds of conductive materials,silver plate and indium tin oxide(ITO)glass,were chosen as the anode,while the cathode was fixed as ITO glass.The simulated conjecture on the effect of electrode flatness on the uniformity of deposited nanoparticles in silver is experimentally proved.More importantly,it was demonstrated that with a relatively smooth and flat ITO glass anode,a SERS substrate featuring higher spectrum uniformity could be achieved.This work is of great significance to the actual applications of the SERS substrate for quantitative detection with high sensitivity. 展开更多
关键词 SERS Raman spectrum surface flatness nanoparticle distribution ELECTRODEPOSITION
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Nodal Topological Phases in s-wave Superfluid of Ultracold Fermionic Gases
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作者 Bei-Bing Huang Xiao-Sen Yang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2018年第2期137-142,共6页
The gapless Weyl superfluid has been widely studied in the three-dimensional ultracold fermionic superfluid. In contrast to Weyl superfluid, there exists another kind of gapless superfluid with topologically protected... The gapless Weyl superfluid has been widely studied in the three-dimensional ultracold fermionic superfluid. In contrast to Weyl superfluid, there exists another kind of gapless superfluid with topologically protected nodal lines, which can be regarded as the superttuid counterpart of nodal line semimetal in the condensed matter physics, just as Weyl superfluid with Weyl semimetal. In this paper we study the ground states of the cold fermionic gases in cubic optical lattices with one-dimensional spin-orbit coupling and transverse Zeeman field and map out the topological phase diagram of the system. We demonstrate that in addition to a fully gapped topologically trivial phase, some different nodal line superfluid phases appear when the Zeeman field is adjusted. The presence of topologically stable nodal lines implies the dispersionless zero-energy fiat band in a finite region of the surface Brillouin zone. Experimentally these nodal line superfluid states can be detected via the momentum-resolved radio-frequency spectroscopy. The nodal line topological superfluid provide fertile grounds for exploring exotic quantum matters in the context of ultraeold atoms. 展开更多
关键词 gapless topological superfluid nodal line surface flat band
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