Elliptical Elements Research Articles

Polarization analysis and filtering of undersampled 3C seismic data in the frequency-slowness domain

Polarization filters have emerged as a useful tool for coherent noise denoising in multicomponent seismic data. By exploiting the polarization properties of seismic waves, these filters can significantly improve wave-type separation, which is a crucial step in seismic data processing. However, their effectiveness in land seismic data in complex areas can be impacted by the presence of scattering noise, and their applicability is limited by irregular spatial sampling, which hinders velocity information for wave-type discrimination. To address these limitations, we introduce a novel two-step method for distinguishing and separating polarized wave types in shot gathers captured from a spatially undersampled linear array of 3C vector sensors. The first step involves conducting a polarization analysis in the frequency-slowness domain using elliptical elements derived from the linear Radon transform of the seismic data. The second step isolates specific polarized waves using the 3C frequency-slowness polarization filter (3C-FSPF), a technique that uses tailored taper functions based on polarization analysis. Our method stands out from single-station filters that cannot use velocity information for wave-type discrimination and existing multistation filters that require regularly sampled data. To evaluate our method, comprehensive tests are conducted on synthetic and real data. The results consistently demonstrate the effectiveness of 3C-FSPF in separating diverse polarized wave types under conditions of irregular and sparse spatial sampling and noise. Our findings underscore the potential of this method for advancing exploration geophysics by enhancing the quality of seismic data, particularly in land regions with complex near-surface structures.

Multiband circularly-polarized stacked elliptical patch antenna with eye-shaped slot for GNSS applications

Abstract This paper introduces a tri-band stacked elliptical patch antenna featuring a right-handed circular polarized, designed to operate at the L2, L5, and L1 Global Navigation Satellite System bands. Initially, an elliptic patch is constructed and fed by a probe feed to generate TM110 and TM210 modes at resonance frequencies calculated using Mathieu functions. The probe position is precisely adjusted to excite the quasi-orthogonal mode of TM110 to generate circularly polarized (CP) waves at the L2 and L5 bands. Subsequently, an eye-shaped aperture is engraved into the elliptical patch to enhance the axial ratio (AR) beamwidth in the L2 and L5 bands and stimulate the orthogonal mode of TM210 to produce CP waves at the L1 band. Lastly, a stacked partially elliptical parasitic element is placed beneath the upper slotted elliptical patch to enhance the orthogonality of TM210 surface current versions and thus improve the AR beamwidth at the L1 band. The proposed antenna shows low reflection coefficient values at 1.12–1.33 (L2/L5), and 1.5–1.66 GHz (L1). The AR beamwidths are 133/213∘, 167/163∘, and 36/103∘ at two orthogonal cutplanes at L5, L2, and L1 bands, respectively. The antenna also has decent gains of 6–6.9 dBic across the three bands.

Polarization-controlled ultrasmall single photon emitter combining a quantum dot and an elliptical split ring metamaterial element

We propose a polarization-controlled ultrasmall single-photon emitter that combines a single photon source and an elliptical split ring (SR) type metamaterial element. Simulations using the finite difference time domain method showed that in elliptical metamaterial elements, the annular mode is suppressed and axial electric field oscillations occur preferentially, resulting in upward light emission from the photon source with controlled polarization. We fabricated prototype devices by focused ion beam lithography and PbS quantum dots. Evaluation of the optical properties of the devices revealed that the emission spectrum width was narrower and the emission lifetime was shorter than those of quantum dot ensemble, and that the polarization was controlled along the minor axis of ellipse. These suggested that the quantum dot emission and the metamaterial element resonated as expected. The combination of a single quantum dot and a single elliptical SR-type metamaterial element was shown to have the potential to operate as a polarization-controlled single-photon emitter.

The influence of aspect ratios of two elliptical cylinders on the solid-liquid phase change flow

Nowadays, phase change materials are widespread in different engineering applications including cooling of electronics, thermal performance in building elements, heat exchangers, and many more. It is critical to gain thorough comprehension on phase change material behavior. The present research aims to numerically simulate phase change material in a heat storage unit having two isothermal elliptical elements. The formulated partial differential equations have been solved by the finite element technique taking into account the enthalpy-porosity approach and adaptive mesh refinement technique. The developed computational code has been validated using numerical and experimental data from the literature. The influence of the aspect ratios of the two elliptical cylinders on the melting phenomenon has been scrutinized, and the most efficient shapes have been identified. It has been found that more intensive melting occurs when the aspect ratios of the upper and lower cylinders are ARu = 0.25 and ARl = 4.0, with a reduction of 18.45 % in the melting time compared to the case with ARu = ARl = 1.0. Furthermore, the case with ARu = 1.0 and ARl = 0.5 shows the longest melting time, with an increase of 0.6 % in the melting time compared to the case with ARu = ARl = 1.0.

On the performance of freestanding rolling mode triboelectric nanogenerators from rotational excitations for smart tires

In this study, we propose a novel freestanding rolling mode triboelectric nanogenerator (FR-TENG) for harvesting energy generated by tire rotation, located within the tire to achieve optimal energy capture. First, to investigate the operating principles of the FR-TENG, the finite element method (FEM) is conducted to predict the potential distribution of spherical rolling elements. Additionally, we employ an atomic-scale electron cloud potential well model to describe the electron transfer mechanism. Second, kinematic simulation is employed to examine the motion state of rolling elements of varying sizes and shapes at different rotation speeds. The results demonstrate that the cylindrical and spherical rolling elements exhibit more stable motion performance compared to the elliptical cylindrical rolling element. Third, the effect of rolling element shapes and sizes on the output performance of the FR-TENG is investigated through systematic experiments. At a rotation speed of 120 rpm, the maximum power of the sphere (diameter 20 mm) reaches 5.33 μW with a load resistance of 50 MΩ. The maximum volume power density of the FR-TENG reaches 3.29 W/m3 when the rolling element is a cylinder (width 22 mm). Regarding charging ability, the cylindrical rolling element outperforms the spherical rolling element by achieving a higher charging voltage. The FR-TENG can charge a 22 μF capacitor to 4.4 V and continuously drive a watch for 20 s. This study provides a comprehensive outlook on the design and configuration of freestanding triboelectric-layer mode TENGs, which can aid in the development of energy recovery systems for vehicle tire rotation.

Whole Elliptical Surface Polishing Using a Doughnut-Shaped MCF Polishing Tool with Variable Tilt Angle

Elliptical elements are essential optical surfaces for modifying optical systems. For polishing the whole elliptical surface using doughnut-shaped MCF polishing tool with variable tilt angle, an experimental investigation was conducted in this work. Firstly, a flat workpiece was polished to determine the polishing feasibility. It was found that the middle portion of the polishing tool had optimal ability to remove materials, and the surface roughness Sa at the material removal peak was changed from 134 nm to 17.5 nm within 50 min of polishing. A smoother surface could be obtained using MCF2 slurry and MCF3 slurry, but the use of MCF1 slurry resulted in a rough surface. Then, the effects of working gap h, revolution speed of MCF polishing tool and polishing time on the polishing results were tested to study the polishing characteristics. Sa 9.6 nm and glossiness 278 Gu were obtained, and form error improved from 2.3 μm to 1.3 μm. Finally, the MCF polishing tool was dried to observe the microstructure of the MCF polishing tool after polishing. Abrasive particles were distributed evenly after polishing. It was seen that the abrasive particles were grabbed by the ferric clusters, and the α-celluloses were interleaved between the clusters.

Fractal loaded six element multiple‐input‐multiple‐output antenna configuration for super wideband operation

In this article, a planar six port multiple-input-multiple-output (MIMO) antenna configuration, fabricated on 80 × 120 mm2 FR4 substrate has been presented for super wideband (SWB) operation. The different co-planar waveguide (CPW) fed antenna elements are placed in side by side, perpendicular and upside down arrangements among themselves. A combination of Minkowski and modified Hilbert fractal curve has been applied on half elliptical patch antenna elements. Two pairs of antenna elements operate from 1.2 to 20 GHz and the other pair of antenna elements covers a bandwidth ranging from 1.4 to 20 GHz. Due to the utilization of different metallic stubs, fractal curves and proper positioning of the antenna elements, inter-element isolation more than 20 dB is achieved over the whole frequency band. The proposed design also exhibits suitable radiation characteristics with enough gain and better diversity performance parameters. The time-domain analysis of the proposed design in terms of group delay also confirms its application as a good SWB MIMO antenna configuration.

Resonance modes of periodically structuralized microwave magnetic elements

Here we consider a flower-like structure of a resonator consisting of six elliptical elements, referred to as petals, made from a magnetic material. The petals are positioned with their centres at the corners of a regular hexagon. Using numerical simulations (CST Studio) we examine the effect of different radial orientations of petals. We study resonance modes with a specific distribution of the electromagnetic field within the resonator as well as the effect of the rotation of petals on the field distribution. The mode character is crucial to understand the behaviour of the frequency spectrum. E.g., the rotation of petals influences significantly the frequency of the lowest mode only, while the other frequencies are almost unchanged and this effect is directly related to the profiles of modes. The system studied is a promising candidate for a tuneable component of an integrated detection system.

Single-polarization single-mode hollow-core negative curvature fiber with nested U-type cladding elements

Hollow-core negative curvature fibers (HC-NCFs) have become one of the research hotspots in the field of optical fiber because of their potential applications in the data and energy transmissions. In this work, a new kind of single-polarization single-mode HC-NCF with nested U-type cladding elements is proposed. To achieve the single-polarization single-mode transmission, we use two different silica tubes in thickness, which satisfy the resonance and anti-resonance conditions on the U-type cladding elements and the cladding tubes, respectively. Besides, the elliptical elements are introduced to achieve good single-mode performance. By studying the influences of the structure parameters on the propagation characteristics, the optimized structure parameters are obtained. The simulation results show that when the wavelength is fixed at 1550 nm, the single-polarization single-mode transmission is achieved, with the polarization extinction ratio of 25749 and minimum high-order mode extinction ratio of 174. Furthermore, the confinement loss is only 0.0015 dB/m.

Exploration of hybrid cladding elements in chalcogenide hollow-core fibers for low-loss mid-infrared transmission

Optical losses of chalcogenide negative curvature hollow-core fibers with hybrid cladding elements were numerically investigated in this study. Microstructured cladding formed by the combination of tubular and elliptical elements was designed for low-loss operation in the mid-infrared spectrum. A confinement loss value of 0.287 dB/km was calculated for the proposed ellipse-nested tubular negative curvature fiber with optimized design parameters at 10.6 µm. Achieved confinement losses with the proposed design are several orders of magnitude lower than the tubular/elliptical negative curvature fibers in the targeted spectrum. The effect of the material absorption to the total fiber losses was also investigated along with the confinement losses. Suppression on the higher-order modes by the proposed fiber was numerically observed. The negative curvature fibers are promising for the low-loss guidance of CO2 lasers that are widely used for various applications spanning from material processing to surgery.

RESEARCH OF THE STRESS STATE OF AN ELLIPTICAL ELEMENT OF PIPELINE UNDER POWER AND CORROSION EFFECT

The stress state of an element of a thick-walled pipeline when ovalizing a cross section is studied under conditions of power and corrosion effect in the statement of plane deformation.  The material of the element under the influence of external loads goes into an elastic-plastic state. The corrosive effect of a pumped medium leads to softening of the material in the plastic zone. This softening of the material is taken into account by a special inhomogeneity function in the Tresca-Saint-Venant plasticity condition. The elastic-plastic problem for an thick-walled elliptical element under uniform external and internal pressure is considered in non-axisymmetric setting. The problem is solved by the method of sharing static and physical equations for the considered elastoplastic material and the perturbation method in the theory of an elastoplastic body. An assessment of the strength and bearing capacity of a loaded thick-walled elliptical element under presence and absence of corrosion damage is given.

Optical conveyor belt based on a plasmonic metasurface with polarization dependent hot spot arrays.

In this Letter, we propose a novel metasurface conveyor belt with periodic orientated arrays of gold plasmonic elliptical elements (GPEEs), which can be continuously lit in a relay way by switching the polarization of the excitation beam and can be used to trap, transport, and sort particles. The array of the hot field can provide a larger trapping area and better stiffness. With the incident optical intensity of 0.08mW/µm2, the depth of the potential well could be as high as 10KBT. By setting a narrow interval between plasmonic ellipses in principal axes, it can help further enhance their directional resonant coupling and polarization dependence. Furthermore, based on consideration of the Brownian motion of trapped particles in aqueous solution, we analyzed its time response property of particle manipulation with different applied switching frequencies from a statistical point of view. As confirmed by numerical analysis, our design offers a novel scheme of particle sorting using a scalable hot spot array with better performance, which could be used in many on-chip optofluidic applications.

Substantiation of Parameters of Friction Elements of Bernoulli Grippers With a Cylindrical Nozzle

The article provides a step-by-step justification of the parameters of the friction elements of the Bernoulli gripping devices with a cylindrical nozzle. The effect of friction element parameters on the lifting force of Bernoulli grippers with the classic design of the active surface and with the rounded-off nozzle and flat and toroidal surface is considered. Influence of friction elements location radius on grip lifting force is considered. Influence of friction elements shape on grip lifting force is considered. Effect of friction coefficient between friction elements of grip and object of manipulation on minimum required lifting force in order to perform handling operation is investigated. Influence of number of friction elements on Bernoulli grip lifting force is considered. For the grip design with the rounded-off nose and flat and toroidal surface when the elliptical friction elements overlap the end gap by 73%, the lifting force will increase by 7% in torsion with the lifting force without the friction elements.

Cervical tooth anatomy considerations for prefabricated anatomic healing abutment design: A mathematical formulation

Statement of problemA custom emergence profile offers the ideal horizontal dimensions for an anatomic healing abutment. However, developing such an emergence profile can be a time-consuming and complex process. PurposeThe purpose of this study was to develop a mathematical formula defining horizontal cervical tooth geometry to design prefabricated, tooth-specific, healing abutments. Material and methodsCone beam computed tomography (CBCT) horizontal cross sections of 989 teeth on 54 participants were measured. For anterior and premolar teeth, 2 perpendicular ellipses were fitted onto the cervical tooth cross section that was defined by 3 parameters. The lingual ellipse followed the lingual outline of the tooth, and its diameter was the largest mesiodistal diameter of the tooth (parameter “a”); its buccolingual radius became parameter “b.” The buccal ellipse was perpendicular to the lingual ellipse and followed the buccal outline of the tooth. The buccolingual radius of the smaller ellipse became parameter “c.” For molars, the first ellipses followed the mesial outline of the tooth, and its larger diameter (parameter “a”) matched the largest buccolingual diameter of the tooth. Its smaller radius became parameter “h1.” The second ellipse was parallel to the first ellipse and followed the distal outline of the tooth. Its larger diameter became parameter “b”, and its mesiodistal diameter became parameter “h2”. Statistical differences between parameters were evaluated by the linear mixed model (α=.05 after Bonferroni adjustment). Pairwise comparisons were made separately for each parameter of the molars and separately for each parameter for the anterior teeth plus premolars. Teeth were put into the same parameter cluster if no significant differences were found between them for a specific parameter. If neither parameter (4 for molars and 3 for the other teeth) was different for 2 teeth, they were put into the same abutment cluster. The abutment clusters determined the type of anatomic healing abutment. The areas were calculated from the developed mathematical formula by using the parameters. In addition, cervical areas of 106 randomly chosen teeth were measured directly with a photo-editing software program. A computer algorithm was used to select 5 CBCT scans from the 54 by using the simple randomization method. The agreement between the 2 methods was evaluated by Bland-Altman analysis. ResultsThe lower and upper limits of agreement between the 2 methods were -8.57 and 7.36 mm2, respectively, with no bias (-0.61 mm2, P=.224). Significant differences were found between most parameters among the 14 tooth types (P<.001). Based on the parameters, 12 specifically distinct clusters were defined. Two tooth types were pooled into 1 abutment cluster: the maxillary first and second premolars and the mandibular first and second molars. ConclusionsThe cervical tooth cross section can be accurately defined by combining 2 elliptical elements. A comprehensive array of tooth specific emergence profiles can be provided by just 12 different prefabricated abutments, designed as per the recommended parameters.

Dispersion properties of artifi cial topological insulators based on an infi nite double-periodic array of elliptical quartz elements

Subject and Purpose. Special features of all-dielectric electromagnetic analogues of topological insulators (TI) in the microwave range are considered, aiming at studying the influence of geometrical and constitutive parameters of TI elements on the dispersion properties of topological insulators based on a two-dimensional double-periodic array of dielectric elements. Methods and Methodology. The evaluation of dispersion properties and electromagnetic field spatial distribution patterns for topological insulators is performed using numerical simulation programs. Results. The electromagnetic analogue of a topological insulator based on a double-periodic array of elliptical quartz cylinders has been considered. By numerical simulation, it has been demonstrated that the electromagnetic properties of the structure are controllable by changing the quartz uniaxial anisotropy direction without any changes in other parameters. A combined topological insulator made up of two adjoining ones differing in shapes of their unit cells has been considered with the numerical demonstration that frequencies of surface states are controllable by choosing the quartz uniaxial anisotropy direction. It has been shown that it is at the interface of two different in shape unit cells that the electromagnetic field concentration at a surface state frequency takes place. Conclusion. A possibility has been demonstrated of controlling microwave electromagnetic properties of topological insulators by changing their geometric parameters and permittivity of the constituents. From a practical point of view, topological insulators can be used as components of microwave transmission lines and devices featuring very small propagation loss.

A nuclear magnetic resonance echo data filter method based on gray-scale morphology

Nuclear magnetic resonance (NMR) echo data measured in the oil field usually have a very low signal-to-noise ratio (S/N). The low S/N of echo data may affect the accuracy of the inversion results, which further leads to the inaccuracy of derived petrophysical parameter estimates. It is therefore important to filter the echo data to enhance the S/N before inversion. Existing filter methods focus on removing noise by compressing the echo data matrix or processing the echo data in time or frequency domain, which are not very efficient and can be affected by artificial interventions. We have developed a gray-scale morphology filter method based on the morphological difference between the echo data and noise. Either elliptical or triangular structure elements can be used for the morphology filter of NMR echo data. The size of the structure elements should be in the range of 1–5 echo spacings to prevent the echo data from being distorted. Comparing the inversion results of the unfiltered, morphology-filtered, singular value decomposition (SVD)-filtered, and wavelet-filtered echo data at different S/Ns, the morphology filter method yields the best results at low S/Ns and the morphology filter method and the wavelet filter method yield similarly good results at high S/Ns. The morphology filter method has the shortest run time compared to the SVD method and the wavelet filter method. Moreover, this morphology filter method is stable to handle random noise and different [Formula: see text] distribution models, and it also performs well on NMR well-logging data.

Photometric Measurements on Sloped Areas by a New Conical–Elliptical Surface Element

One of the important issues in photometry and radiometry is the surface area calculation, or knowing its relative surface element for any integration or other metrology aims. In this paper, firstly, we have reviewed the oblique cross-section of a right circular cone (OCRCC), then we have derived how to choose an elementary surface area or infinitesimal small patch on the elliptical surface of OCRCC, accurately. This surface element derivation maybe looks ordinary, but it has a major importance to calculate a part of the OCRCC surface. Such geometrical element can be applied to solve physics problems included certain lighting and photometry issues. Therefore, we have produced and presented related schemes and illustrative examples, then we have solved certain of them numerically by “Mathematica”. These examples clarify the lighting or photometric applications of this new surface element and validate its correctness.

Ultra-Wideband Planar Antenna with Notched-Band for WIMAX, WLAN and MSAT Applications

Ultra-wideband (UWB) with triple band notch characteristics was presented. WIMAX, WLAN and Meteorological Satellite (MSAT) frequency bandwidths were rejected in the UWB planar antenna composed from a single layer conductor element. Frequency bandwidths for WIMAX, WLAN and MSAT are allocated at 3.3~3.7, 5~6 and 7.4~8.4GHz, respectively. Conductor element etching method was used as the means to realize the band notch characteristics as it was considered convenient and simple. Two slits were etched on the ground plane while on the elliptical element, a single slit. The slits were designed for simplicity in the means of achieving the desired band notch characteristics. The proposed antenna design was compact and low profile. The antenna performances were compared with the reference antenna and the results were negligible.

Band Rejections for WLAN and WIMAX Utilizing UWB Planar Antenna by Slits in the Conductor Elements

Band rejections for WLAN and WIMAX frequency bandwidths are realized in a UWB planar antenna utilizing a single slit in an elliptical element. WLAN and WIMAX communication system frequency bandwidths have been known to coexist with the UWB frequency bandwidth. Coexistence of multiple frequency bandwidths are susceptible to disadvantage and could cause interferences to other communication system. The disadvantages could be in form of signal disruption, data loss and equipment malfunctions [1–3]. Thus, it is essential to eliminate WLAN frequency bandwidth from the UWB communication system. Slits are employed to influence the exterior current distribution on the radiator and therefore, has generated mismatched of the input impedance. The phenomenon has caused the band notch characteristic and thus, rejected the frequency bandwidths for 5 to 6 and 3.3 to 3.7GHz, respectively. The structures of the slits are simple in a compact design of the UWB planar antenna. The UWB planar antennas with band rejections are compared with the reference antenna. The reflection coefficients S11 for the designed UWB planar antennas have rejected the frequency bandwidths for 5 to 6 and 3.3 to 3.7GHz, consecutively. The peak of the notched-band reflection coefficient S11 for the frequency bandwidths 5 to 6 and 3.3 to 3.7GHz are about -3 and -4dB, respectively. Surface currents are distributed in the slit areas. The radiation patterns are illustrated for the frequency 3.5, 7.5 and 9.5GHz for the single notched-band, while 4.5, 7.5 and 9.5GHz for the dual notched-band characteristics. Radiation patterns for the single and dual notched-band in the H- and E-planes for the designed antennas are in omni- and bi-directional, respectively. Maximum gains G are in the —z and -x direction in the H- and E- plane, for the UWB planar antenna with single and dual notched-band characteristics.

An outburst of delta Pavonids and the orbit of parent comet C/1907 G1 (Grigg-Mellish)

The CAMS New Zealand meteor shower survey detected a brief outburst of delta Pavonids (IAU shower 120, code DPA) with a compact radiant on March 31, 2019. This is the first instrumental detection of a shower long suspected to exist by visual observers monitoring the theoretical radiant of parent comet C/1907 G1 (Grigg-Mellish), despite it being listed in comet catalogs only with a parabolic orbit. The 2019 detection of an associated meteor shower confirms that this comet moves in an elliptical orbit. The range of allowed orbit solutions fitted to the 1907 observations of the comet strongly correlate node and semi-major axis. Taking into account the difference in node between comet orbit and dust trail, the time of the outburst constrains the comet orbital period to 447 ​± ​80 years (heliocentric), having last been near the sun in A. D. 1460 ​± ​80 years. The corresponding elliptical orbital elements for C/1907 G1 are presented. The short 23-min duration of the outburst (FWHM ​= ​16 ​min) confirms that C/1907 G1 is a small comet, having ejected dust with low ejection speeds. It passed close enough to Earth orbit to be a potentially hazardous comet in future returns.