Cross Plane Research Articles

Preferred Configuration and Detection Limits Estimation of Magnetic Gradient Tensor System

The magnetic gradient tensor system (MGTS) based on the fluxgate sensors array replaces partial differentials with the sensors reading difference to approximate the magnetic field gradient, but it introduces structural errors at the mean time. A good structure design with reasonable parameters can reduce structural errors and expand the theoretical detection range of the MGTS. From the analysis of the complete 18-uniaxial MGTS, five simplified structures of the MGTS were summarized, which include the plane cross, equilateral triangle, square, right-angle tetrahedron, and regular tetrahedron. The differential magnetic gradient tensor measurement matrixes of different structures were also provided, where we found the plane-cross structure produces the smallest structural error. Moreover, the theoretical detection limits expression of the MGTS to the magnetic dipole was derived. The detection limit boundary of the MGTS is related to the sensor’s accuracy, the array baseline distance, and the magnetization direction and magnetic moment magnitude of the source. In actual heading-line surveys, the magnetic moments of four typical small magnets were successfully estimated by the magnetic dipole positioning method, and the theoretical detection limits of the built plane-cross MGTS aiming at the four magnets were estimated. The results show that the estimation accuracy of the theoretical detection limits of MGTs is ±0.5 m.

Runaway blue main-sequence stars at high Galactic latitudes

Context. The ESA Gaia mission is a remarkable tool for stellar population analysis through its accurate Hertzsprung–Russell diagram. Its precise astrometry has propelled detailed kinematic studies of the Milky Way and the identification of high-velocity outliers. Aims. Motivated by the historical identification of runaway main-sequence (MS) stars of an early spectral type at high Galactic latitudes, we test the capability of Gaia at identifying new such stars. Methods. We selected ≈2300 sources with Gaia magnitudes of GBP − GRP ≤ 0.05, which are compatible with the colors of low-extinction MS stars that are earlier than a mid-A spectral type, and obtained low-resolution optical spectroscopy for 48 such stars. By performing detailed photometric and spectroscopic analyses, we derived their atmospheric and physical parameters (effective temperature, surface gravity, radial velocity, interstellar reddening, spectrophotometric distance, mass, radius, luminosity, and age). The comparison between spectrophotometric and parallax-based distances enabled us to disentangle the MS candidates from older blue horizontal branch (BHB) candidates. Results. We identify 12 runaway MS candidates, with masses between 2 and 6 M⊙. Their trajectories were traced back to the Galactic disk in order to identify their most recent Galactic plane crossings and the corresponding flight times. All 12 candidates are ejected from the Galactic disk within 2 to 16.5 kpc from the Galactic center and possess flight times that are shorter than their evolutionary ages, which is compatible with a runaway hypothesis. Three MS candidates have ejection velocities exceeding 450 km s−1, thus, they appear to challenge the canonical ejection scenarios for late B-type stars. The fastest star of our sample also has a non-negligible Galactic escape probability if its MS nature can be confirmed. We identify 27 BHB candidates, and the two hottest stars in our sample are rare low-mass stars of late O- and early B-types, evolving towards the white dwarf cooling sequence. Conclusions. The combination of Gaia parallaxes and proper motions can lead to the efficient selection of runaway blue MS candidates up to 10 kpc away from the Sun. High resolution spectra are needed to confirm the MS status, via precise measurements of projected rotational velocities and chemical compositions.

Dynamic Stability of a Three-Layer Beam – Generalization of the Sandwich Structures Theory

The subject of the study is a simply supported three-layer beam of the length L, width b and total depth h subjected to a pulsating axial force (Fig.1). The individual hypothesis-theory of deformation of the plane cross section is assumed for the purpose of modelling of the beam with consideration of the shear effect in the layers. The hypothesis is a generalization of the classical sandwich theory – broken line hypothesis (Fig.2).

Bistability and hidden attractors in the paradigmatic Rössler'76 system.

In this paper, the dynamics of the paradigmatic Rössler system is investigated in a yet unexplored region of its three-dimensional parameter space. We prove a necessary condition in this space for which the Rössler system can be chaotic. By using standard numerical tools, like bifurcation diagrams, Poincaré sections, and first-return maps, we highlight both asymptotically stable limit cycles and chaotic attractors. Lyapunov exponents are used to verify the chaotic behavior while random numerical procedures and various plane cross sections of the basins of attraction of the coexisting attractors prove that both limit cycles and chaotic attractors are hidden. We thus obtain previously unknown examples of bistability in the Rössler system, where a point attractor coexists with either a hidden limit cycle attractor or a hidden chaotic attractor.

Raman Tensor of Layered SnS2.

Recently, tin disulfide (SnS2) has become a hot research focus in various fields due to its advantages of a high transistor switching ratio, an adjustable band gap in visible light range, excellent Li storage performance, sensitive gas recognition, and efficient photocatalytic capability. However, at present, studies of its basic structure mostly stay on the regulation related to the number of layers. To maximize the value of SnS2 in the application design, this paper analyzes the angle-resolved polarized Raman spectra of SnS2 crystals grown under high-temperature sealing systems. Under the parallel scattering configuration test of both the sample basal plane and the cross plane, we observed that how the Raman scattering intensity of the two test planes varies with the polarization angle is different. Combining this experimental result with theory support allows us to reach a conclusion that the differential polarizability of the phonon vibration mode along the z-axis of the cross plane of SnS2 is proven to be the strongest. This finding is expected to provide favorable support for the application of structural regulation of SnS2 and work as a reference for studying other van der Waals layered materials with greater potential.

Areal analysis induced bias on interface thickness around ovoidal particles

Two-dimensional image analysis is usually used to obtain the thickness of the interfacial transition zone (ITZ) around aggregates. However, if the two-dimensional section plane crosses through the ITZ region but not through the corresponding aggregate, this region (called invalid region) will be excluded from the analysis. This exclusion will induce bias in estimating the thickness t of the ITZ. This paper proposes a methodology to quantify the bias on the ITZ thickness induced by areal analysis. The approach includes three parts: (1) Uniform ITZ layers around ovoidal aggregates are generated based on the Minkowski sum; (2) A systematical cap sampling method (SCSM) is proposed to estimate the volume of the invalid region VITZiv; (3) By combining with VITZiv, the underestimation degree of the ITZ thickness for dilute mono- and multi- packing systems are calculated. The results reveal that the underestimation degree increases with the increasing sphericity of aggregates.

Research and Application of Optimizing Pre-drainage Hole Layout along Seam

In order to solve the problem of the unsatisfactory pre-drainage effect of bedding holes, based on the theory of elastoplastic mechanics, the distribution of elastoplastic zone around the borehole and its influencing factors were analyzed, and it was found that the three-dimensional arrangement of the boreholes can increase the hole circumference of the drilled network Plastic zone volume, effective drilling length of borehole, coal seam permeability and gas drainage efficiency. Engineering application was carried out at the 3215working face of Wangpo Coal Mine. Three test schemes of dense parallel drilling, plane cross drilling and three-dimensional cross drilling were used, and the effect of extraction was investigated for comparative analysis. The test shows that the extraction efficiency of the three-dimensional cross-drilled hole is high, and the attenuation coefficient is small. Under the same amount of drilling, the extraction capacity of the three-dimensional cross-drilled hole is 1.7 times and 1.3 times that of the dense parallel drilling and plane cross-drilled hole. The drainage efficiency of three-dimensional cross drilling is 69% and 26% higher than that of dense parallel drilling and plane cross drilling, respectively.

The bias of the interface thickness and diffusivity of concrete comprising Platonic aggregates induced by areal analysis

The micro-structure of three-dimensional (3D) interfacial transition zone (ITZ) in concrete is usually investigated by one-dimensional (1D) and two-dimensional (2D) analyses. However, the information obtained in 1D and 2D cannot be directly used to characterize the actual 3D microstructure. If the two-dimensional section plane crosses through the ITZ region but not through the corresponding aggregate, this invalid region will be excluded from the analysis. Due to this exclusion, the ITZ thickness is underestimated and ultimately lead to a biased estimation of the contribution of the ITZ to the overall performance of the concrete. In this work, the underestimation of the ITZ thickness of concrete comprising mono- and multisized Platonic aggregates are investigated. By combining the underestimated ITZ thickness with a differential effective medium approximation, the bias on diffusivity of concrete induced by the areal analysis is evaluated. The results reveal that the bias increases with the increasing sphericity of aggregates.

Raman tensor of layered black phosphorus

Black phosphorus has a strong Raman anisotropy on the basal and cross planes due to its orthorhombic crystal structure. However, almost all the studies on black phosphorus’ anisotropy focus on basal plane with the cross plane neglected. Here, we performed a systematic angle-resolved polarized Raman scattering on both the basal and cross planes of black phosphorus and obtained its integral Raman tensors. It is discovered that when the polarization direction of excitation light is along different crystal axes, the Raman intensity ratio (Ixx : Iyy: Izz) of {A}_g^1 mode is 256:1:5. Besides, via calculation, it is confirmed that the strong Raman anisotropy mainly comes from different differential polarizability alone different directions. This phenomenon is also observed when it comes to the {A}_g^2 mode.

Raman tensor of layered black arsenic

AbstractDue to the similar atom arrangement with black phosphorus, black arsenic also has obvious Raman anisotropy at both the base and cross planes. However, the polarization characteristics of black arsenic have been rarely reported so far with most relevant studies devoted to the base plane. Here, to compensate for the blank of the anisotropy in cross plane, we implemented a systematical angle‐resolved polarized Raman measurement on both planes of layered black arsenic and observed that the Raman intensity ratios (Ixx : Iyy : Izz) of optical phonons and modes along different axes are 1:4.8:2.76 and 6.9:1:5.7, respectively. Based on the definition of Raman intensity, we abstracted integral Raman tensors of black arsenic. In addition, according to density functional theory, it can be affirmed that the Raman anisotropy of Ag mode is sourced from the anisotropy of differential polarizability along different crystal axes.

Tin Selenide Molecular Precursor for the Solution Processing of Thermoelectric Materials and Devices.

In the present work, we report a solution-based strategy to produce crystallographically textured SnSe bulk nanomaterials and printed layers with optimized thermoelectric performance in the direction normal to the substrate. Our strategy is based on the formulation of a molecular precursor that can be continuously decomposed to produce a SnSe powder or printed into predefined patterns. The precursor formulation and decomposition conditions are optimized to produce pure phase 2D SnSe nanoplates. The printed layer and the bulk material obtained after hot press displays a clear preferential orientation of the crystallographic domains, resulting in an ultralow thermal conductivity of 0.55 W m-1 K-1 in the direction normal to the substrate. Such textured nanomaterials present highly anisotropic properties with the best thermoelectric performance in plane, i.e., in the directions parallel to the substrate, which coincide with the crystallographic bc plane of SnSe. This is an unfortunate characteristic because thermoelectric devices are designed to create/harvest temperature gradients in the direction normal to the substrate. We further demonstrate that this limitation can be overcome with the introduction of small amounts of tellurium in the precursor. The presence of tellurium allows one to reduce the band gap and increase both the charge carrier concentration and the mobility, especially the cross plane, with a minimal decrease of the Seebeck coefficient. These effects translate into record out of plane ZT values at 800 K.

Research and application of pre-draining coal seam gas technology with three-dimensional cross drilling

In view of the current situation of low extraction efficiency and poor extraction efficiency of Yangquan No.5 mine 15# coal seam in, in order to ensure the daily safe and efficient production of coal mines, the three-dimensional cross-drilling technology was used to conduct field test on the drainage effect of the bedding in the 8401 working face, and compared with the gas drainage technology of traditional drilling arrangement methods such as plane cross hole and parallel hole arrangement. The result shows that after the gas extraction of the three-dimensional cross-drilled hole in the 8401 working face, the average extraction volume per 100 meters reaches 0.0097m3/min.hm, the attenuation coefficient is 0.0725d−1, and the extraction effect is better than that of the plane-intersecting holes and the parallel arrangement of holes, which effectively reduces the occurrence of coal mine accidents and opens up a new technical way for coal mine gas drainage.

First principles study of electronic structure and thermoelectric transport in tin selenide and phase separated tin selenide–copper selenide alloy

The electronic structure and thermoelectric transport in SnSe and its alloy with Cu2Se have been studied using the first principles technique and semi classical Boltzmann transport theory. Our study reveals that SnSe is p-type with indirect band gap of 0.66 eV, while the alloy is phase separated and n-type with negligible indirect band gap of 0.064 eV. In both cases, two fold degeneracy in band extrema have been observed within the range of 25 meV. Delocalization of Se lone pair has been observed due to Cu substitution in Sn sites, which is supposed to lower its lattice thermal conductivity. A chemical potential map has been generated obeying thermodynamic restrictions to predict the possible existence of secondary phases. Our study shows the existence of SnSe2 as a secondary phase, while the possibility of Cu2Se as a secondary phase is negligible due to its higher formation energy. We calculated the transport coefficients as a function of carrier concentration and temperature to understand the range of optimized thermoelectric performance. The transport coefficients are similar along in plane direction whereas significant deviation is observed along the cross plane direction due to anisotropy in effective masses in SnSe. The effective masses are more isotropic in alloy than SnSe, thus transport properties show less anisotropy along three directions. Significant contribution of bipolar transport is observed in SnSe, while that is not noticed in the alloy. The behaviors of the Seebeck coefficients in both cases are discussed in terms of Mott’s theory and density of states modification near Fermi energy. Electron mobilities limited by acoustic phonon, ionized impurities, alloy scattering and inter carrier scattering have been examined relying on deformation potential approach and effective mass theory. The results indicate that acoustic phonon scattering is dominant scattering mechanism in SnSe over inter carrier scattering, whereas for the alloy the former contribute very weakly. Ionized impurity scattering and inter carrier scattering are most dominant in the alloy. Alloy scattering with U = 2 eV also contribute significantly.

Numerical prediction of slamming loads during water entry of a slender hull

The water entry of a slender hull with 5 degrees of freedom (5-DOF), except surge, at a prescribed speed is investigated through a strip theory together with the boundary element method. The hull is cut into a series of slices, the motion of each slice is equivalent to the water entry of a two-dimensional (2D) wedge, which can be solved through the boundary element method in the time domain, with the fully nonlinear boundary conditions imposed on the free surface. In each slice or cross plane, the pressure on the body can be calculated through an auxiliary function method. The total force and moment can then be obtained through an integration scheme along the longitudinal direction of hull. Results are provided for pressure distribution, free surface deformation, the forces and moments, and the influence of the hull velocities is discussed in depth.

Investigating the plasma parameters and discharge asymmetry in dual magnetron reactive high power impulse magnetron sputtering discharge with Al in Ar/O2 mixture

Dual magnetron reactive high power impulse magnetron sputtering (dual magnetron R-HiPIMS) provides a deposition process favor for low temperature crystallization of high quality dielectric films. However, lack of detailed measurements is blocking the accurate understanding of the resulting film quality to the plasma parameters. In this work, a dual magnetron R-HiPIMS discharge with Al in a fixed Ar/O2 mixture has been investigated by means of time-resolved Langmuir probe and energy-resolving quadrupole mass spectrometry. Fine temporal resolution of the measured probe characteristics revealed a rapidly climbing and sinking followed by a gradual increasing again in the plasma potential (Vp), floating potential (Vf) and effective electron temperature (Teff) during the pulse-on period. In the pulse-off time, two-fold decay, the initial fast drift decay and the subsequent slower diffusive decay, was observed for these parameters. While for the electron density (ne), it demonstrated a steep increase up to 60 μs after the initial of voltage pulse, followed also by a two-stage exponential-like decrease with two characteristic decay times of τ1 = 80 μs and τ2 = 120 μs in the remainder of the off-time. Ion energy distribution functions (IEDFs) were recorded in time averaged and time resolved mode for 36Ar+, 27Al+, 16O+ and 32O2+ ions. Time averaged results showed that there are generally two peaks in the corresponding IEDFs — a lower peak corresponding to Vp and a high energy tails originate from different physical mechanisms. The time evolution of the ion fluxes corresponds well with discharge current and revealed the sequential arrival of working gas ions (36Ar+ and 32O2+) and ions ejected from the targets (27Al+ and 16O+). Moreover, for the first time, the plasma parameters (Vp, Vf, Teff and ne) at symmetry positions (y = −40 mm and y = 40 mm) with respect to the plane of geometric symmetry of the dual magnetron (the plane crosses both axes of the magnetrons) are compared, and the observed asymmetry behavior of Vf, Teff and ne is explained in view of “the gradient drift” of high energy electrons pointing to the +y direction.

Anisotropy of Excitons in Two-Dimensional Perovskite Crystals.

Two-dimensional (2D) perovskites show great potential for optoelectronic applications due to their bandgap tunability, extremely large excition binding energy, and large crystal anisotropy compared with their three-dimensional counterparts. To fully explore exciton-based applications and improve their performance, it is essential to understand the exciton behavior in 2D perovskites. Here, we investigate exciton anisotropy within the crystallographic plane and cross plane of (C4H9NH3)2PbI4 2D perovskite crystals by polarization-resolved photoluminescence, reflection, and photoconductivity studies. We observe a polarization-dependent emission evolution and an enhanced self-trapped exciton emission with an oblique incident excitation from the cross plane. Furthermore, the anisotropy of excitons in (C4H9NH3)2PbI4 2D perovskite crystals is identified by polarization-resolved photoluminescence and photoconductivity measurement, and a completely opposite polarization-dependent behavior was observed for free excitons and self-trapped excitons. We attribute this different anisotropy to the existence of out-of-plane excitons and different optical selection rule for free excitons and self-trapped excitons. Our findings will shed light on designing and improving the performance of exciton-based optoelectronic devices in 2D perovskites.

Maneuvering simulation of an X-plane submarine using computational fluid dynamics

X-plane submarines show better maneuverability as they have much longer span of control plane than that of cross plane submarines. In this study, captive model tests were conducted to evaluate the maneuverability of an X-plane submarine using Computational Fluid Dynamics (CFD) and a mathematical maneuvering model. For CFD analysis, SNUFOAM, CFD software specialized in naval hydrodynamics based on the open-source toolkit, OpenFOAM, was applied. A generic submarine Joubert BB2 was selected as a test model, which was modified by Maritime Research Institute Netherlands (MARIN). Captive model tests including propeller open water, resistance, self-propulsion, static drift, horizontal planar motion mechanism and vertical planar motion mechanism tests were carried out to obtain maneuvering coefficients of the submarine. Maneuvering simulations for turning circle tests were performed using the maneuvering coefficients obtained from the captive model tests. The simulated trajectory showed good agreement with that of free running model tests. From the results, it was proved that CFD simulations can be applicable to obtain reliable maneuvering coefficients for X-plane submarines.

A Low-Profile Third-Order Half-Mode SIW Filtering Antenna With Low H-Plane Cross Polarization and Good Sideband Suppression

A new type of low-profile filter antenna with low H -plane cross polarization (cross-pol) and good suppression of sidebands is proposed using multifunction single slot and five shorting pins integrated into half-mode substrate integrated waveguide (SIW). Initially, the TM1,3/2 mode, the TM1,5/2 mode, and the TM3,1/2 mode have been excited successively in the low H -plane cross-pol SIW. Then, in order to realize third-order half-mode radiation of the antenna, the five shorting pins and the key slot have been used to reallocate those modes above. In addition, the slot also introduces two transmission zeros at 4.94 and 6.12 GHz to improve the filtering characteristic and to suppress the sidebands of the antenna. Finally, the filtering antenna is designed at 5.16 GHz with 2.5% impedance bandwidth for WLAN wireless communication application. The attenuation for lower sideband is always below 30 dBi, while the corresponding bandwidth for upper sideband achieves high out-of-band suppression levels of 20 dBi is about 1.52 GHz. The cross polarization can reach below –30 dB; meanwhile, its gain in frequency band is 6.79 dBi above. In addition, the low-profile property has been obtained with the height of 0.0087 free-space wavelength.

INVESTIGATION OF BAND LOOP FRAME ARTICULATED CONTEINER TRUCK STABILITY BY MOTION ON THECHNOLOGICAL ROADS

Mathematical model of disturbance motion for articulated container truck with band loop frame on pneumatic wheels by different conditions of cross stabilization has been worked out by analytical mechanics method with Lagrange equation of second type. Analytical expressions of critical parameters of system, which define stability of articulated container truck in cross plane has been received.

A Low-Profile Printed Cavity Antenna With Simultaneous Bandwidth and Radiation Pattern Improvement

A low-profile printed cavity antenna (PCA) under triple-mode resonance is proposed towards a simultaneous impedance bandwidth and a radiation pattern improvement. Based on the cavity model, the far-zone radiated fields of the PCA are theoretically investigated. The results demonstrate that its E -plane half-power beamwidth (HPBW) could be significantly improved by using two half-mode cavities instead of a single-patch resonator. After that, the width of the radiating patch is progressively enlarged and separated in order to excite three resonant modes for bandwidth-enhancement. Moreover, two additional conductive vias are loaded below the radiating patch in order to reduce its increased E -plane cross polarization. In final, the proposed antenna is fabricated and tested. Experimental results show that its impedance bandwidth is obviously extended to about 14.3% with appearance of three in-band attenuation poles. Meanwhile, a low-profile property with the height of 0.027 free-space wavelength is achieved. In particular, the PCA has acquired a wide E -plane HPBW of around 135°, while keeping a low cross polarization of below –20 dB in both E- and H-planes.