Surface Majorana flat bands in j=3/2 superconductors with singlet-quintet mixing

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.

Study of corrective abrasive finishing for plane surfaces using magnetic abrasive finishing processes

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.

Laser-induced breakdown spectroscopy as a method for millimeter-scale inspection of surface flatness

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.

Particulate Matter Exposure of Rural Interior Communities as Observed by the First Tribal Air Quality Network in the Yukon Flat

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.

Convective heat transfer on flat and concave surfaces subjected to an impinging jet form lobed nozzle

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.

High-quality micro-shape fabrication of monocrystalline diamond by nanosecond pulsed laser and acid cleaning

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.

Absolute surface form measurement of flat optics based on oblique incidence method

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.

Classification of Flat Lagrangian Surfaces in Complex Lorentzian Plane

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.

ON MINIMAL IMMERSIONS OF R^2 INTO THE NEARLY KAHLER S^6

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.

Improvement of Raman spectrum uniformity of SERS substrate based on flat electrode

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.