Axial Ratio Research Articles

Review on Intrinsic Shape of Elliptical Galaxies

: Elliptical galaxies, as one of the fundamental types of galaxies, have attracted astronomers due to their intriguing properties. In this review, we explore the intrinsic shape of elliptical galaxies, a field that plays a pivotal role in understanding their formation, evolution, and interactions within the cosmos. Methods for intrinsic shape determination using photometric and kinematic methods are extensively discussed. The use of photometric data and surface brightness profiles to derive the intrinsic shapes of elliptical galaxies is examined and triaxial models are reviewed. Constraining the intrinsic shapes of elliptical galaxies is crucial to understanding their formation histories. Elliptical galaxies are characterized by their ellipsoidal, rather than disk-like, shapes, and understanding the underlying factors and their intrinsic shapes of elliptical galaxies determination provides valuable insights into their formation, evolution, and the broader context of galaxy morphology. One key aspect of studying the intrinsic shape of elliptical galaxies involves the analysis of their axial ratios, which describe the flattening of the galaxy along different axes. The axial ratio is defined as the ratio of the semi-minor axis to the semi-major axis of the ellipse representing the galaxy's cross-section. The intrinsic shape can vary from nearly spherical (axial ratio close to 1) to highly elongated (axial ratio significantly different from 1).

A metasurface for linear-to-circular polarization conversion and sensing based on quasi-BIC

This work presents a multifunctional metastructure (MS) which realizes linear to circular polarization conversion and sensing function based on quasi-bound states in the continuum (quasi-BIC). MS is made of silicon dioxide as substrate, and silicon as surface material, by etching cross holes and square holes on it to form a 2 × 2 structure, through the transmission of terahertz (THz) band, to form an ultrahigh quality factor (Q-factor), and realize the conversion of linearly polarized waves to circularly polarized ones. At 178.190 THz, it achieves a Q value of 2969, and in the range 178.193 TH to 178.200 THz, the axial ratio (AR) is less than 3 dB and the insertion loss is less than 0.0001. In addition, by changing the permittivity of the surrounding environment, the minimum of the output wave will produce a good linear frequency shift. Using this feature, the given device can also be used as a dielectric constant sensor to detect air quality. The device has a sensing sensitivity (S) of 6.415 THz RIU−1 and a figure of merit (FOM) of 106.9. The parameters (H, w2, L2, g2), incidence angle (θ) and the polarization angle (φ) are discussed. The effects of different parameters on the Q-factor and AR were analyzed, which helped to select the optimal parameters. The design can also be used in communication and biosensing.

Combined bending-torsion and compression-bending-torsion behaviours of reinforced concrete-filled thin-walled corrugated steel tubes

Reinforced concrete-filled thin-walled galvanized corrugated steel tube (RCFCST) is a novel composite member that has application potential in extremely corrosive environments and seismic activity regions. A series of preliminary works have been conducted on its compressive, flexural, shear, and torsional behaviour. However, the combined loading condition is almost inevitable in practice. The correlations between the flexural and torsional behaviour of RCFCSTs are unique due to the special spiral corrugated profile, which is unclear and needs to be addressed. This paper, therefore, presents an experimental investigation of the RCFCST under combined bending-torsion and compression-bending-torsion loads, encompassing the main test variables of torsion-to-bending ratios, torsional directions, and axial compression ratios. The loading set-up and instruments have been introduced in detail. The failure modes, lateral load versus lateral displacement curves, bending moment versus flexural lateral displacement curves, torsion moment versus torsional angle curves, and strain distributions are carefully addressed. The working mechanisms of the RCFCST under monotonic combined loads are discussed, with a particular explanation of the dependent behaviour on the torsion-to-bending ratios and torsional directions. The applicability of the existing design methods for the bearing capacity of RCFCST specimens under combined loads is examined carefully, with specific design suggestions proposed.

A single-feed circularly polarized antenna with a low vertical profile and hemispherical axial-ratio beam coverage

ABSTRACT A novel wide axial-ratio beamwidth (ARBW) circularly polarized (CP) antenna with a single layer substrate fed by a single probe is proposed. It consists of an inner annular slotted radiator containing eight outer sector units with arc branches, a ground plane, and eight grounded vias. The antenna has an ARBW covering the upper hemisphere and has a low vertical profile. The ultra-hemispherical ARBW is formed by ingeniously merging the endfire omnidirectional CP radiation pattern with the boresight CP radiation pattern. The two radiation patterns can be excited by a central coaxial probe without an additional feeding network. An antenna prototype of dimensions 1.15 × 1.15 × 0.02 (λ 0 3) is fabricated and measured to validate the design concept. Measured results show that the impedance bandwidth of the proposed antenna is 2.0% (3.328–3.394 GHz) and the 3 dB axial ratio (AR) bandwidth is 1.3% (3.332–3.374 GHz). The 3 dB AR beamwidth can cover more than 217° and the maximum gain is 0.79 dBic at 3.35 GHz. A good agreement between the simulated and measured results is obtained.

Numerical investigation on plastic hinge behavior of hybrid steel-FRP reinforced concrete columns

This paper presents a numerical study on the plastic hinge behavior and rotation capacity of concrete columns reinforced with a combination of steel bars and fiber-reinforced polymer (FRP) bars. A meso-scale numerical model, which considers the internal heterogeneity of concrete and bond behavior between concrete and longitudinal reinforcements, was developed and validated. The failure modes, lateral load-displacement responses, and the physical plastic hinge lengths of hybrid steel-FRP reinforced concrete (SFRC) columns were investigated and compared with those of conventional steel-reinforced concrete columns. The results indicated that the steel yielding zone and curvature localization zone of SFRC columns with FRP longitudinal bars were enlarged, due to the relatively low modulus of FRP bars. After that, a parametric analysis was performed to study the plastic hinge length of SFRC columns with respect to the nominal area ratio of FRP longitudinal bars, shear span-to-depth ratio, axial load ratio, and longitudinal reinforcement ratio. A new empirical model was proposed to predict the equivalent plastic hinge length, which was subsequently integrated into an analytical method for predicting the ultimate rotation. The comparison of predictions with simulation and test results demonstrated the accuracy of both the proposed empirical model and analytical method.

Research on layout optimization for propellers of a submarine operation vehicle

The submarine operation vehicle was an important equipment for exploring the marine environment and performing underwater tasks. In this paper, the calculation and analysis of hydrodynamic performance and the layout optimization of the propellers under different layouts were completed. Based on the left-right symmetrical layout of the four ducted propellers, the two ducted propellers were taken as the research object to optimize its vector layout, and an approximate model was constructed according to the numerical calculation results under different combinations of propeller spacing and deflection angle. The simulation calculation and verification are carried out, and the optimal layout of the four ducted propeller were determined considering the interference between the ducted propellers on both sides. Finally, an experimental platform for the thrust test of the two ducted propellers were built. It was found that the axial thrust ratio of the rear propeller and the front propeller in experimental results were in good agreement with the simulation results, which verified the feasibility of using the numerical simulation method to study the mutual interference between the ducted propellers.

Experiment and restoring force model study of precast shear walls with new rabbet-unbonded horizontal connection

The 'rabbet-unbonded horizontal connection' (RUHC) is a new connection form of precast shear wall. This study conducted a low-cycle repeated loading test on three RUHC walls to investigate the hysteretic performance of the walls with the 'axial compression ratio' and 'unbonded level' as the main variables and the results showed that the above two parameters remarkably affected the seismic performance of RUHC walls. Based on the analysis of test skeleton and hysteresis curve characteristic, the influence of parameters such as axial compression ratio and unbonded level on the load and displacement during the loading process was analyzed. The theoretical values of yield, peak and limit points were calculated, and the skeleton curve model was proposed. Moreover, the unloading stiffness formula was proposed by the non-linear relation of dimensionless parameters and Matlab software fitting, and the hysteresis rule model was established. Finally, a three-fold-linear restoring force model of RUHC walls composed of the theoretical skeleton curve and hysteresis rule was established and verified. This model provides an effective prediction for the hysteresis characteristics and a theoretical basis for conducting elastic-plastic analysis of RUHC structures.

Experimental and simulation study on seismic performance of seawater sea-sand PVA cementitious composite columns with GFRP bars

The seismic properties of seven seawater sea-sand (SWSS) PVA cementitious composite columns with Glass Fiber Reinforced Polymer (GFRP) bars were studied. The effects of four parameters, namely polyvinyl alcohol (PVA) fiber content, axial compression ratio, cementitious composite strength and stirrup spacing, on the seismic performance of composite columns were analyzed. The failure of the specimen was observed, and the hysteresis curve, skeleton curve, stiffness degradation, energy dissipation capacity, ductility and strain of the specimen were analyzed. The test results show that the large chip-based spalling will occur when the specimen without fiber incorporation is damaged, and the incorporation of PVA fiber, the reduction of stirrup spacing and the reduction of axial compression ratio will delay the rate of crack formation and development. In addition, through cross-section analysis and considering the reinforcement effect of PVA fibers, a proposed formula for calculating the horizontal bearing capacity of composite columns is proposed. Finally, the finite element model of SWSS PVA cementitious composite columns with GFRP bars is established, and it is found that increasing the strength grade of cementitious materials can greatly improve the seismic performance of composite columns. The conclusions could be references for the engineering application. In the context of the global emphasis on green development and environmental protection, seawater and sea-sand cementitious composites and components with fiber reinforcement will have a wide range of application prospects in the construction of coastal areas.

Research on seismic performance and axial compression ratio of rectangular high-strength spiral stirrup confined concrete columns

Replacing traditional stirrups with high-strength rectangular spiral stirrups can improve the seismic performance of reinforced concrete columns. In order to study the seismic performance of high-strength spiral stirrup confined concrete columns, a validated finite element (FE) method was proposed to establish the FE model of reinforced concrete columns. Combined with the measured data of two existing specimens, parameter analysis was conducted on 19 specimens. The axial compression ratio, shear span ratio, stirrup spacing, and stirrup diameter were variable parameters. Based on a reliable model, internal stress analysis was conducted, and the influence of different variables on the seismic performance of reinforced concrete columns was revealed. The FE results suggest that, when the axial compression ratio is not greater than 0.6, the requirement of ductility greater than 3 in the Chinese Standard GB 50011-2010 can be met. The recommended shear span ratio for optimal ductility was around 4.5. The reinforcement ratio of high-strength spiral stirrups ranges from 1.0% to 2.2%. After completing the simulation of nearly 100 specimens (only calculating the ductility coefficient), a matching relationship between the axial compression ratio limit and the shear span ratio was proposed.

A wideband dual-circularly polarized traveling wave dielectric resonator antenna array

ABSTRACT In order to meet the demand of high capacity and high speed transmission of satellite communication system, a wideband dual-circularly polarized dielectric resonator antenna (DRA) array is proposed based on the traveling wave principle. Four DRA elements with slot-coupling excitation are sequentially placed on the ground, and the feeding network is designed to realize the two orthogonal circular polarization radiation waves. A notched copper loop (NCL) around the antenna array is adopted to improve the radiation performance. Depending on the operation of the two ports, the NCL generates the induced currents which rotates clockwise/counterclockwise, increasing the axial ratio bandwidth. In order to further improve the gain stability, the copper sheets are embedded on the top surface of each radiation element, and the copper cylinders perturb the internal field distribution of the DRA to introduce higher-order modes. The measurement results show that the left-hand circular polarization and the right-hand circular polarization operating bandwidths are 11.8% (14.97–16.85 GHz) and 12% (14.91–16.82 GHz). The antenna gain achieves 9.0 dBic. This DRA array can be applied for the vehicle mounted RF terminals in satellite communication.

Wideband circularly polarized dielectric resonator antenna with multi-functional metasurface assistance for low profile

ABSTRACT A low-profile broadband circularly polarized (CP) dielectric resonator antenna (DRA) is proposed, utilizing DR reutilization and metasurface (MS) techniques. Two resonant frequencies and an AR minimum are achieved simultaneously, by exciting a rectangular DR with an inclined corner-truncated coupling slot, for it generates nearly degenerated TE111 modes. For significant bandwidth enhancement and low profile, a new resonator is formed by reusing the DR and loading an MS above, which works in orthogonal TM modes. To increase the axial ratio bandwidth (ARBW) further without enlarging the antenna size， two parasitic patches are printed on two adjacent side walls of the DR. To verify the rationality and feasibility, the antenna is fabricated and measured. The fabricated prototype possesses the profile of 0.06λ 0 (λ 0 is the free-space wavelength at the center frequency). The measured impedance bandwidth (IBW) and ARBW are 36.05% (4.23 ~ 6.09 GHz) and 22.46% (4.9 ~ 6.14 GHz), respectively. The proposed antenna has both broadband characteristics and a low profile, making it easy to integrate into space-limited wireless communication systems with high data rates.

Metasurface‐based circularly polarised antenna: Enhanced bandwidth with characteristic mode analysis and symmetric branch design

AbstractA low‐profile circularly polarised (CP) metasurface antenna is proposed, utilising characteristic mode analysis (CMA). The antenna design features a two‐layer laminated substrate, a 4×4 Butterfly‐shaped metasurface, a rectangular slot, an irregular transmission line, and a ground plane. The metasurface is analysed using mode significance (MS), characteristic angle (CA), and characteristic current to determine the resonance bandwidth and CA resonance points, which exhibit a near 90° difference. At the intersection of the two MS modes, their CAs differ by nearly 90°, and their far‐field radiation directions align, indicating the potential for achieving circular polarisation at the desired frequency. The integration of the metasurface with the slot antenna is simulated to validate the CMA findings. Additionally, the CP bandwidth is enhanced by modifying the transmission line branches. Measurement of the fabricated antenna reveals an impedance bandwidth (IBW) of 27.4%, a 3‐dB axial ratio bandwidth (ARBW) of 10.1%, and a peak gain of 6.9 dBic at 4.4 GHz. Compared to the design without branches, IBW and ARBW have increased by 10% and 7.3%, respectively.

Structural Analysis for Qazzaz Metamorphic Core Complex, Northwestern Arabian Shield, Saudi Arabia

AbstractIdentifying deformational mechanisms and associated structures at various scales, ranging from regional‐scale structures to microscopic fabric, is crucial for the assessment of tectonic development. Thirty‐three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic minerals. These samples included gneisses rocks, monzogranite, and metavolcano–sedimentary rocks for both the Thalbah and Bayda groups. Using the Rf/j and Fry methods, the axial ratios (XZ) range about 2.20 to 7.10 and 1.90 to 9.10, respectively. For various rock units, the strain measurements show moderate to highly deformation. Most of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain (X). The short axes (Z) based to be subvertical foliation related with a subhorizontal foliation. The results demonstrate that contacts generated at semi‐brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic units. It concluded that nappe generation in orogens results from pure shear deformation.

JADES Ultrared Flattened Objects: Morphologies and Spatial Gradients in Color and Stellar Populations

One of the more surprising findings after the first year of JWST observations is the large number of spatially extended galaxies (ultrared flattened objects, or UFOs) among the optically faint galaxy (OFG) population otherwise thought to be compact. Leveraging the depth and survey area of the JWST Advanced Deep Extragalactic Survey, we extend observations of the OFG population to an additional 112 objects, 56 of which are well-resolved in F444W with effective sizes, R e > 0.″25, more than tripling previous UFO counts. These galaxies have redshifts around 2 < z < 4, high stellar masses ( log(M*/M⊙)∼10–11 ), and star formation rates around ∼100–1000 M ⊙ yr−1. Surprisingly, UFOs are red across their entire extents, which spatially resolved analysis of their stellar populations shows is due to large values of dust attenuation (typically A V > 2 mag even at large radii). Morphologically, the majority of our UFO sample tends to have low Sérsic indices (n ∼ 1) suggesting that these large, massive, OFGs have little contribution from a bulge in F444W. Further, a majority have axis ratios between 0.2 < q < 0.4, which Bayesian modeling suggests that their intrinsic shapes are consistent with being a mixture of inclined disks and prolate objects with little to no contribution from spheroids. While kinematic constraints will be needed to determine the true intrinsic shapes of UFOs, it is clear that an unexpected population of large, disky or prolate objects contributes significantly to the population of OFGs.

Lateral performance of circular wooden columns reinforced with high-performance bamboo-based composite

This study researches the lateral performance of wooden columns strengthened with the non-damage reinforcement method, which used high-performance bamboo-based composite (HPBBC) materials and steel strips to form a hollow reinforcement system and then jacketed and reinforced the wooden columns. Six wooden columns strengthened by non-damage reinforcing methods were subjected to low cyclic loading tests under horizontal loads with a constant axial pressure ratio. The horizontal loads, displacements, and strain distributions of different locations at the column root were measured. The experimental results showed that the reinforcement method improved the lateral performance of wooden columns by about 4.96–58.54 %. Owing to the protective effect of the reinforcement system, the development of tensile damage to the wooden columns was delayed, but the breaking location was still the column root. In addition, the energy dissipation capacity and equivalent viscous damping coefficient of the reinforced wooden columns were significantly improved. The deformation of the strengthened column root conforms to the plane section assumption, while the deformation of the reinforcement system was lagged due to the absence of colloid and shear connectors between the wooden column and the reinforcement system. A bending capacity equation for the reinforced wood column was deduced based on the strain distribution in the damaged section. The error between the calculated and experimental results was within 13 %.

Effects of aggregates and fibers on the strength and permeability of concrete exposed to low vacuum environment

The performance and regulation of concrete in low vacuum environments are receiving increasing attention. This study investigates the effects of aggregates and fibers on the strength and permeability of concrete in a low vacuum environment, using varying gradients of sand ratios (37.5 %, 40 %, and 42 %) and aggregate-to-binder ratios (3.27, 3.92, and 4.14). Three types of non-metallic fibers are utilized: polyethylene (PE), polyvinyl alcohol (PVA), and glass fibers. Evaluations focus on concrete strength, mass loss, gas permeability, capillary water absorption, and porosity. Results indicate that higher sand and aggregate-to-binder ratios enhance both flexural and compressive strength. Fiber incorporation improves flexural and compressive toughness, with PE fibers showing the most significant toughening effect. The low vacuum environment increases the strength of the concrete but reduces its axial compression toughness ratio and increases brittleness, while fiber incorporation helps improve the compression toughness of the concrete. Higher sand and aggregate-to-binder ratios reduce mass loss and accelerate drying equilibrium, while fibers increase mass loss and prolong drying equilibrium, with PVA fibers causing greater mass loss. The pattern of concrete mass loss can be explained by the tortuosity of the moisture diffusion path. Additionally, low vacuum significantly increases the gas permeability of concrete. Enhancing the sand and aggregate-to-binder ratios reduces permeability both before and after low vacuum treatment. Although fibers increase the gas permeability, they help mitigate this increase under low vacuum condition. Capillary water absorption tests reveal that concrete under low vacuum condition has a significantly higher water absorption rate compared to air-drying condition. Increasing sand and aggregate-to-binder ratios reduces water absorption and capillary water content, whereas fibers have the opposite effect. Porosity tests show that moisture migration in a low vacuum environment is mainly related to permeable porosity, while total porosity is more closely related to compressive strength.

Advantages of Plate Antennas over Loop Antennas for Circular Polarization—Its Application in Array Antenna with a Simplified Feed

We analyze square antennas with one and quasi-two sources to reveal the relationship between loop and plate antennas. First, using the moment method, one-source antennas with corner truncation are investigated versus antenna height above the ground plane. As the height increases, the CP wave bandwidth of the plate antenna increases 17% for a 3 dB axial ratio criterion, whereas the loop antenna’s bandwidth remains less than 3%. Next, we study quasi-two-source antennas without corner truncation versus antenna height. The plate antenna’s bandwidth is found to reach 30%, which is wider than that of a loop antenna by a factor of two. Last, the plate antenna with quasi-two sources is applied in an array antenna, whose properties are compared to those of the corresponding loop antenna array. We present experimental results to verify the simulated results.

Frequency-reconfigurable liquid crystal metasurface array

In this paper, a frequency-reconfigurable metasurface (MS) circularly polarized antenna array (CPAA) based on liquid crystal (LC) is presented. The antenna features a multilayer structure. Design of the MS circularly polarized antenna unit using the characteristic mode analysis method, the combination of MS structure, temperature-controlled LC, and sequential feed network not only enhances the impedance bandwidth (IBW), axial ratio bandwidth (ARBW), and gain. By adjusting the temperature to change the relative dielectric constant of the LC, further frequency reconfigurability of the CPAA is achieved. Under different temperature control settings, the effective IBW and ARBW of the antenna can be shifted from 39.0% (4.51–6.70 GHz) to 40.3% (4.61–6.94 GHz), while the peak gain moves from 11.59 dBi at 5.31 GHz to 11.71 dBi at 5.41 GHz. The results demonstrate that the proposed MS CPAA offers advantages of wide bandwidth, high gain, low profile, and frequency reconfigurability.

Broadband polarization-adjustable antenna realized by waveguide circular polarizers.

A broadband polarization-adjustable antenna realized by two waveguide circular polarizers is proposed in this paper. The antenna consists of a rectangular-to-circular transition waveguide, two identically structured rectangular slot circular polarizers, and a conical horn, all connected in sequence. By rotating the two circular polarizers to specific angles, the antenna can switch among four polarization modes: horizontal polarization, vertical polarization, left-hand circular polarization, and right-hand circular polarization. The antenna polarization adjustment principle is thoroughly analyzed. Taking the X-band polarization-adjustable antenna as an example, simulation and optimization were performed, and a prototype was fabricated and measured. The antenna's reflection coefficient is below -18 dB across all polarization modes from 9.2 to 10GHz. In linear polarized modes, gains exceed 10.5 dBi. For circular polarized modes, the gains align with those of linear modes, with an axial ratio of less than 1 dB in the operating frequency band. The measured results are consistent with the simulation results, confirming its excellent polarization adjustment performance and potential for high power microwave applications.

Axial Ratio Improved and Beamforming Enhanced Circularly Polarized Phased Array

Axial Ratio Improved and Beamforming Enhanced Circularly Polarized Phased Array