Oblique Angle Research Articles

Design of Band Stop Filter Using Epsilon-Negative Frequency Selective Surface

This paper focuses on designing a band stop filter based on epsilon-negative frequency-selective surface (FSS). The unit cell has an electrical length of 0.104λ0 × 0.104λ0 which offers a bandwidth of 2.53 GHz from 1.24 GHz to 3.77 GHz. It has a center frequency of 2.44 GHz and the obtained fractional bandwidth is above 100%. Additionally, the behavior of the presented FSS is explained by the equivalent circuit model and surface current distribution. Within the entire bandwidth, it offers a negative permittivity. The refractive index of BSF is almost zero for 2.45−3.98 GHz range of frequency. The proposed FSS structure exhibits polarization-independent properties and offers a stable frequency response for normal and oblique angles under both TE and TM polarization. Good agreement between the simulated and measured results is obtained for the designed prototype.

Controlled generation of cylindrical vector vortex beams using an optically active material

An efficient method for the generation of tunable cylindrical vector vortex beams is proposed and demonstrated experimentally using an optically active (OA) material. The uniqueness of the proposed methodology lies in the control over the tunability of the cylindrical vector vortex beams using different concentrations of the optically active material. The efficiency of the generated beams is enhanced by using a single low oblique incidence angle of the input beam on a spatial light modulator with a single-phase profile. Two global parameters are measured experimentally to show the quantitative tunability and efficiency of the generated beams. The proposed method can find applications in the fabrication of various kinds of spiral nanostructures.

Medial Joint Opening in the Operated Knee After Unilateral High Tibial Osteotomy: Risk of Osteoarthritis and Future Surgery in the Operated and Nonoperated Knee.

High tibial osteotomy (HTO) modifies the mechanics of the affected knee but can also affect the nonoperated knee. However, no research has reported on the prognosis and risk factors related to the nonoperated knee after unilateral HTO. To assess the radiological parameters associated with osteoarthritis (OA) progression and the need for surgery in the nonoperated knee after unilateral HTO, with concurrent assessment of the operated knee. Case series; Level of evidence, 4. The medical charts of 197 patients with knee OA who underwent unilateral HTO between March 2007 and December 2020 were retrospectively investigated. Radiological parameters such as the Kellgren-Lawrence grade, weightbearing line ratio, joint line convergence angle (JLCA), and joint line obliquity angle were assessed preoperatively and 1 year postoperatively. The mean follow-up length for the 197 patients was 5.9 ± 3.2 years for the operated knee and 5.5 ± 3.2 years for the nonoperated knee. A smaller postoperative JLCA in the operated knee was a significant risk factor for OA progression (P = .027) and undergoing surgery (P = .006) in the nonoperated knee. Conversely, a larger postoperative JLCA in the operated knee was a significant risk factor for OA progression (P = .014) and conversion to arthroplasty (P = .027) in the operated knee. A postoperative JLCA >1.5° (P < .001) and <3.9° (P < .001) was needed to reduce the risk of undergoing surgery in the nonoperated knee and OA progression in the operated knee, respectively. Additionally, a pre- to postoperative change in the JLCA (ΔJLCA) between -5.6° and -1.7° (P = .021 and P = .004, respectively) was needed to reduce the risk of OA progression in both knees. A large medial joint opening (a small postoperative JLCA) in the operated knee after unilateral HTO was associated with a higher risk of OA progression and surgery in the nonoperated knee. Conversely, a small medial joint opening (a large postoperative JLCA) was associated with a higher risk of OA progression and conversion to arthroplasty in the operated knee. For a balanced medial joint opening, if the postoperative JLCA was between 1.5° and 3.9° or the ΔJLCA was between -5.6° and -1.7°, a favorable prognosis in both knees could be anticipated.

Beam steerable MIMO antenna based on conformal passive reflective metasurface for 5G millimeter wave applications

A conformal reflective metasurface fed by a dual-band multiple-input multiple-output (MIMO) antenna is proposed for low-cost beam steering applications in 5G Millimeter-wave frequency bands. The beam steering is accomplished by selecting a specific port of MIMO antenna. Each MIMO port is associated with a beam that points in a different direction due to a conformal reflective metasurface. This novel conformal metasurface antenna design has the advantages of higher gain, lower cost, a simpler feeding source, and a lower profile when compared to traditional reflective metasurfaces using bulky horn antennas and phased arrays with complex feeding networks and phase shifters for beam steering. The proposed beam steering antenna consists of a compact five-element dual-band MIMO and a 32×32\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$32 \ imes 32$$\\end{document} unit-cell conformal dual-band reflective metasurface placed at the top of the MIMO antenna to obtain the beam steering capability as well as gain enhancement. The proposed reflective metasurface has a stable response under oblique incidence angles of up to 600\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$60^0$$\\end{document} at 24 GHz and 38 GHz and its symmetric, single-layer structure, ensures polarization insensitivity and stable response under conformal conditions. The presented MIMO antenna design is not only compact but also offers a wideband response effectively covering the desired 5G mm-wave frequency bands. The overall size of the MIMO antenna alone is 70 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document} 12 mm2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\hbox {mm}^2$$\\end{document} with a maximum gain of 5.4 and 7.2 dB. It is further improved up to 13.1 and 14.2 dB at 24 and 38 GHz respectively, with a beam steering range of ś400\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$40^0$$\\end{document} by using a conformal reflective metasurface. Unlike the existing beam steering strategies, the suggested method is not only cost-effective but also increases the overall directivity and gain of the source MIMO antenna. The measured results agree with the simulated results, making it a potential candidate in the 5G and beyond beam steering applications.

Insights into the relationship between particulate flow characteristics and local erosion behaviour under waterjet: The role of particle-fluid-surface interaction

In this study, the erosion characteristics of eutectic high entropy alloy under the liquid–solid two-phase flow is investigated by a coupled numerical-experimental method, in order to reveal the intrinsic relationship between microscopic erosion mechanism (experimental test) and the related particle-fluid-surface interaction (CFD modelling). Furthermore, instead of the common relation between average erosion rate and mainstream flow velocity, the relationship between local erosion distribution and local particulate flow characteristics is clarified. The erosion rate and erosion pattern match well between the experiment and simulation. The results demonstrate that NiCoCrFeNb0.45 exhibits superior anti-erosion performance when compared to other widely used equipment metals. The erosion profile agrees well with the shape of surface velocity distribution, indicating a close relationship between surface erosion behaviour and flow characteristics. In particular, the erosion pattern at a normal angle appears as a symmetric ring due to the flow stagnation phenomenon, with slight erosion damage in the centre area and severe erosion in the surrounding, whereas the erosion profile at an oblique angle displays an elliptic shape, with severe erosion damage in centre. Notably, the primary erosion mechanism varies dramatically in different surface regions, induced by the various impact velocities and angles associated with the corresponding changes in the flow field. This study provides a deeper understanding of erosion behaviour in terms of the interrelationship among the material mechanical properties, particulate flow field and particle-surface impingement behaviour.

Crossed-cell-tile multiplexed 1st-order gratings, for three-dimensional beam-splitter applications

Oblique angle of incidence two-way and three-way beam splitters were designed and fabricated. The devices feature two first-order diffraction gratings, arrayed crossed in alternating adjacent tiles, resulting in conical diffraction spot separation of two 1 st -orders in orthogonal planes while overlapping the 0 th -order. The two-way beam splitter was designed for 0 th −order suppression. The three-way beam splitter was designed to distribute light equally between the 1 st and 0 th − order spots. Testing of the devices yielded efficiencies of 2%:46%:46% for the two-way beam splitter at 604 nm, and 32%:32%:32% for the three-way beam splitter at 633 nm wavelength. The polarization state of the incident beam was preserved after diffraction through the devices.

Vanadium-dioxide-assisted multifunctional switchable terahertz metamaterial devices

A multifunctional, switchable terahertz (THz) metamaterial (MM) device with wideband absorption and polarization conversion capabilities has been developed, based on the insulator-metal phase transition of vanadium dioxide (VO2). In its metallic state, the device operates as a wideband absorber within the range of 2.56–6.74 THz, achieving a bandwidth of 4.18 THz and an absorption rate of ≥90%. The wideband absorption is insensitive to both oblique incident angles and polarization. When VO2 is in its insulating state, the device switches to a polarization converter, facilitating linear-to-cross polarization (LTX) conversion between 1.04 and 4 THz, and linear-to-circular polarization (LTC) conversion between 1 and 1.04 THz, with a conversion efficiency exceeding 90%. Additionally, the effects of incident angle and polarization angle on the device’s performance were analyzed. This THz device offers advantages of wide angle, wide bandwidth, and high efficiency, making it a valuable reference for research into new multifunctional THz devices. It has great potential applications in short-range wireless THz communication, ultrafast optical switches, high-temperature resistant switches, transient spectroscopy, and optical polarization control devices. In specific application scenarios, particularly in fields requiring efficient detection, transmission, and analysis—such as security and non-destructive testing, secure communication systems, imaging and sensing, multidimensional spectral analysis, pollutant detection, smart stealth coatings, dynamic optical control devices, and integrated optical systems—these devices offer multifunctional capabilities. They enhance system performance and flexibility, meeting diverse application needs.

Solitons in one-dimensional non-Hermitian moiré photonic lattice

We study the excitation and stabilization of gap solitons and dipole solitons in a non-Hermitian moiré photonic lattice with self-focusing effect. The lattice is constituted by superimposition of a parity-time symmetric potential and an anti-parity-time symmetric potential with inconsistent frequencies. We find that the single gap solitons within semi-infinite bandgap can indeed stably persist, and their ss positions within the lattice can be precisely adjusted through controlling the oblique angles and propagation constants of incident solitons. Further study shows that the lattice enables dipole solitons with specific soliton energy to overcome inherent repulsion, facilitating their propagation within the lattice. This work unveils the existence of stable gap solitons supported by non-Hermitian moiré photonic lattices, emphasizing the pivotal roles of propagation constants and incident angles in regulating soliton propagation.

Reflectivity characterization of in-flow acoustic floor treatment for the NASA Langley 14- by 22-Foot Subsonic Tunnel

An experimental campaign was performed to assess acoustic modifications to the NASA Langley Research Center 14- by 22-Foot Subsonic Tunnel. Recent acoustic testing campaigns in this facility have emphasized the reduction of aerodynamic noise due to flow scrubbing across acoustically treated floor baskets. However, the measures implemented to address this noise contaminant have resulted in the installation of floor basket coverings of high acoustic reflectivity. Therefore, a controlled testing campaign was performed to identify a suitable acoustic basket configuration in terms of both acoustic absorptivity and reduced flow scrubbing noise. This testing campaign was conducted in two phases: the first in an anechoic chamber facility on a single acoustic basket panel to identify a notional configuration of acceptable absorptivity, and the second in a complete floor basket installation checkout test in the NASA Langley 14- by 22-Foot Subsonic Tunnel. Results show that the newly implemented floor treatment exhibits suitable performance in both desired categories of acoustic absorptivity and reduced flow scrubbing noise. This campaign has also validated the effectiveness and usefulness of the anechoic chamber test configuration as a means of assessing acoustic reflections at oblique angles of incidence.

LiveLattice: Real-time visualisation of tilted light-sheet microscopy data using a memory-efficient transformation algorithm.

Light-sheet fluorescence microscopy (LSFM), a prominent fluorescence microscopy technique, offers enhanced temporal resolution for imaging biological samples in four dimensions (4D; x, y, z, time). Some of the most recent implementations, including inverted selective plane illumination microscopy (iSPIM) and lattice light-sheet microscopy (LLSM), move the sample substrate at an oblique angle relative to the detection objective's optical axis. Data from such tilted-sample-scan LSFMs require subsequent deskewing and rotation for proper visualisation and analysis. Such data preprocessing operations currently demand substantial memory allocation and pose significant computational challenges for large 4D dataset. The consequence is prolonged data preprocessing time compared to data acquisition time, which limits the ability for live-viewing the data as it is being captured by the microscope. To enable the fast preprocessing of large light-sheet microscopy datasets without significant hardware demand, we have developed WH-Transform, a memory-efficient transformation algorithm for deskewing and rotating the raw dataset, significantly reducing memory usage and the run time by more than 10-fold for large image stacks. Benchmarked against the conventional method and existing software, our approach demonstrates linear runtime compared to the cubic and quadratic runtime of the other approaches. Preprocessing a raw 3D volume of 2 GB (512 × 1536 × 600 pixels) can be accomplished in 3 s using a GPU with 24 GB of memory on a single workstation. Applied to 4D LLSM datasets of human hepatocytes, lung organoid tissue and brain organoid tissue, our method provided rapid and accurate preprocessing within seconds. Importantly, such preprocessing speeds now allow visualisation of the raw microscope data stream in real time, significantly improving the usability of LLSM in biology. In summary, this advancement holds transformative potential for light-sheet microscopy, enabling real-time, on-the-fly data preprocessing, visualisation, and analysis on standard workstations, thereby revolutionising biological imaging applications for LLSM and similar microscopes.

Topography Response to Horizontal Slab Tearing and Oblique Continental Collision: Insights From 3D Thermomechanical Modeling

AbstractThe horizontal propagation of slab detachment (slab tearing) is known to control lateral migration of the mountain uplift along the collisional belt. However, along‐strike differential collision due to an oblique passive margin geometry can make the topography response more complex. In this study, we employ 3D thermomechanical modeling to distinguish between the lateral migration of the mountain topography driven by slab tearing and oblique continental collision itself. In our models, slab breakoff is triggered by the transition from oceanic to continental subduction, occurring earlier on one side of the passive margin than on the other due to the initial oblique configuration. However, once slab breakoff has begun, it spreads horizontally in the form of tearing at high velocity (∼38–118 cm yr−1), and associated topographic uplift also propagates with the same velocity. In contrast, the along‐strike migration of subsequent continental collision and related topographic uplift propagation is typically much slower (∼2–34 cm yr−1). Similarly, the vertical magnitude of surface uplift caused by slab tearing is higher (up to 10 mm yr−1) than the following collision phase (&lt;4 mm yr−1). The parametric analysis reveals that slab tearing velocity and the associated horizontal propagation of mountain uplift depends on obliquity angle and slab age, whereas the migration of collision‐induced topographic growth is controlled by the convergence velocity and obliquity angle. Finally, we show that presence of microcontinental block detached from the passive margin leads to spatial and temporal transition from horizontal to vertical slab tearing and more intense syn‐collisional mountain building.

Acoustic scattering by smooth and rough elastic cylinders insonified by directional sonars: Bistatic experiments.

Bistatic laboratory measurements are presented for acoustic scattering from both smooth and rough elastic cylinders insonified by directional spherical waves. A scattering model, accounting for incident directional spherical waves while assuming negligible end effects, was derived in a previous article [Mursaline, Stanton, Lavery, and Fischell, J. Acoust. Soc. Am. 154, 307-322 (2023)] but only evaluated for monostatic scattering by smooth cylinders. The evaluation is extended here to bistatic geometries for both smooth and rough cylinders. The effect of axi-symmetric Gaussian roughness (axi-symmetric random variations in cylinder radius) on the cylinder on overall scattering levels and resonances is investigated. Particular emphasis is given to the influence of roughness on the excitation of axially propagating guided wave resonances associated with oblique incident angles. Bistatic laboratory observations presented herein further substantiate the effects on scattering due to the properties of the incident field from practical sonars, such as spherical spreading, as observed in the above-mentioned article. For smooth cylinders, axially propagating guided wave resonances are seen to become more prominent during bistatic in-plane scattering compared to bistatic orthogonal-plane scattering and previously published monostatic data. For rough cylinders, both overall scattering levels and resonances are found to be diminished compared to the smooth case.

Hierarchical Nb@NbN core-shell-like nanocolumns for asymmetric supercapacitors

Transition metal nitrides (TMNs) are promising electrode materials for supercapacitors because of their high electrical conductivity and chemical stability. The rational design and facile synthesis of TMNs electrode materials with a unique nanostructure are the key to develop high-performance supercapacitors. Herein, we propose a two-step, binder-free, and eco-friendly approach utilizing magnetron sputtering at an oblique angle deposition configuration to fabricate hierarchical Nb@NbN core–shell-like nanocolumns for supercapacitors. This distinctive heterostructure not only creates lattice defects, increases active surface area, facilitates ion diffusion and charge transfer, but also optimizes the electronic structure and enhances the conductivity. As a result, the hierarchical Nb@NbN core–shell-like nanocolumn electrodes exhibit a high areal capacitance of 53.3 mF cm−2 at 1 mA cm−2 and an excellent capacitance retention of 93.5 % after 20,000 cycles, outperforming pristine NbN and the majority of previously reported TMNs electrodes. Moreover, the assembled Nb@NbN nanocolumns//VN thin films asymmetric supercapacitor device can deliver a maximum energy density of 49.8 mWh cm−3 and power density of 82 W cm−3. This work presents a facile and environmentally friendly strategy for the synthesis of TMNs core–shell-like nanocolumns, and further demonstrates their promising potential for use in supercapacitors.

Why Do Great Continental Transform Earthquakes Nucleate on Branch Faults?

Abstract The five Mw≥7.8 continental transform earthquakes since 2000 all nucleated on branch faults. This includes the 2001 Mw 7.8 Kokoxili, 2002 Mw 7.9 Denali, 2008 Mw 7.9 Wenchuan, 2016 Mw 7.8 Kaikōura, and 2023 Mw 7.8 Pazarcık events. A branch or splay is typically an immature fault that connects to the transform at an oblique angle and can have a different rake and dip than the transform. The branch faults ruptured for at least 25 km before they joined the transforms, which then ruptured an additional 250–450 km, in all but one case (Pazarcık) unilaterally. Branch fault nucleation is also likely for the 1939 M 7.8 Erzincan earthquake, possible for the 1906 Mw∼7.8 and 1857 Mw∼7.9 San Andreas earthquakes, but not for the 1990 Mw 7.7 Luzon, 2013 Mw 7.7 Balochistan, and 2023 Mw 7.7 Elbistan events. Here, we argue that because fault continuity and cataclastite within the fault damage zone develop through cumulative fault slip, mature transforms are pathways for dynamic rupture. Once a rupture enters the transform from the branch fault, flash shear heating causes pore fluid pressurization and sudden weakening in the cataclastite, resulting in very low dynamic friction. But the static friction on transforms is high, and so they are usually far from failure, which could be why they tend to be aseismic between, or at least for centuries after, great events. This could explain why the largest continental transform earthquakes either begin on a branch fault or nucleate along the transform at locations where the damage zone is absent or the fault continuity is disrupted by bends or echelons, as in the 1999 Mw 7.6 İzmit earthquake. Recognition of branch fault nucleation could be used to strengthen earthquake early warning in regions such as California, New Zealand, and Türkiye with transform faults.

In-plane structural and electronic anisotropy of nanoporous Pt films formed by oblique angle deposition

Nanoporous Pt films fabricated by oblique angle deposition hold potential as electrocatalysts in various energy-related fields owing to their high surface area, structural stability, and adequate conductivity. In this study, we investigated the morphology, porosity, and electrical conductivity of nanoporous Pt thin films and systematically studied their interrelationships. Specifically, we revealed an in-plane anisotropy in the electrical conductivity that correlates with the surface morphology of the film. This anisotropy was evident in the resistance measurements along the in-plane lateral and vertical directions, which aligned well with our simple model. The results emphasize the significance of film morphology in determining the film’s electrical properties. This study contributes to the understanding of the physical properties of Pt films fabricated via oblique angle deposition and offers valuable insights for designing nanoporous films for various applications.

Low temperature dependence of electrical resistivity in obliquely sputter-deposited transition metal thin films

Transition metals exhibiting hcp (Ti, Zr, Hf) and bcc (V, Nb, Ta, Cr, Mo, W) crystalline structures are DC sputter-deposited by oblique angle deposition. A constant film thickness of 400 nm is prepared, whereas the deposition angle α is systematically changed from 0 to 85° A columnar structure is produced with column angle reaching β = 50° for the highest deposition angle. Crystallinity and grain size are both reduced with an increasing deposition angle, especially for α higher than 60° DC electrical resistivity vs. temperature in the range 7–300 K shows a typical metallic-like behavior with films becoming more resistive for high deposition angles. For temperatures higher than 100 K, the linear temperature dependence of resistivity is obtained for films prepared with deposition angles lower than 60° The electron-phonon is the main interaction acting on electronic transport mechanism. Oblique deposition angles give rise to an enhancement of electron-phonon interactions with a saturation effect of electrical resistivity for some metals. Resistivity measurements at low temperatures (down to 7 K) show the predominance of electron-defect interactions. Electron-phonon-defect interaction effect is particularly investigated as a function of the deposition angle and a shift of the crossover temperature is brought to the fore.

Numerical investigation of tip clearance designs for oblique-cut fin microchannels

Tip clearance represents a simple design intervention strategy to mitigate the high hydraulic penalties often associated with microchannel heat sinks. This approach has not been widely explored for enhanced microchannel heat sinks, having previously focused only on conventional (uniform) tip clearance design for straight microchannels. In view of this, the present work investigates the performance of an enhanced heat sink, specifically oblique-cut fin microchannels, with tip clearance designs. Two different designs are considered, namely conventional/uniform tip clearance (utc) and a newly conceptualized modulated tip clearance (mtc). Numerical simulations are conducted using ANSYS FLUENT 2022 R1 first for straight microchannels, which are considered the baseline to which oblique-cut fin microchannel designs are compared. The simulations are carried out under laminar flow regime including conjugate heat transfer in a heated solid substrate for flow rates of 250 – 650 mL/min. The results indicate that utc significantly reduces pressure drop though can increase thermal resistance for the oblique channels. The underlying physical mechanisms responsible for this observation are elucidated by examining thermal and flow behaviours in and around oblique cut slots. Based on the flow behaviour in oblique slots with utc, modulated tip clearance (mtc) concept is introduced and investigated. When compared to utc cases, mtc tends to reduce the thermal resistance substantially, though depending upon oblique cut angle and flow rate. However, the Performance Index (PI) shows that utc improves the overall performance in the range of 10–15 % compared to that observed with mtc cases, though the factor of improvement reduces closely to 5 % at 650 mL/min. In addition, the overall performance in terms of heat transfer and hydraulic pumping power further show that utc and mtc design strategies are competitive, and warrant further multi-objective optimization investigations to determine the best design option overall.

Nonlinear Seismic Response of Tunnel Structures under Traveling Wave Excitation

Tunnels traditionally regarded as resilient to seismic events have recently garnered significant attention from engineers owing to a rise in incidents of seismic damage. In this paper, the reflection characteristics of the elastic plane wave incident on the free surface are analyzed, and the matrix analysis method SWIM (Seismic Wave Input Method) for the calculation of equivalent nodal loads with artificial truncated boundary conditions for seismic wave oblique incidence is established by using coordinate transformation technology, according to the displacement velocity and stress characteristics of a plane wave. The results show that the oblique incidence method is more effective in reflecting the traveling wave effect, and the “rotational effect” induced by oblique incidence must be considered for P wave and SV wave incidence, including the associated stress and deformation. This effect exhibits markedly distinct rotational phenomenon. In particular, the P wave incidence should be focused on the vault and the inverted arch due to the expansion wave. With the increase of the oblique incidence angle, the structural stress and deformation are rotated to a certain extent, and the values are significantly increased. Simultaneously, the shear action of the SV wave may result in “ovaling” of the tunnel structure, thereby facilitating damage to the arch shoulder and the sidewall components. As the oblique incidence angle, the potentially damaging effects of the “rotational effect” to the vault and the inverted arch, but the numerical value does not change significantly. In addition, in comparison to a circular cross-section, the low-frequency amplification of seismic waves in the surrounding rock and the difference of frequency response function in different parts of the lining are more pronounced. In particular, the dominant frequency characteristics are significant at P wave incidence and the seismic wave signal attenuation tends to be obvious with increasing incidence angle. In contrast, SV waves exhibit more uniform characteristics.

Measurement of the Breaking Indices of Frequently Ghtching Pulsars using Integration Method

Pulsars are old, stellar objects that emit electromagnetic radiations in a definite time interval, with a predictable smooth spin-down, predisposed to discrete fluctuations/glitches. The rotational frequency of pulsars decays with time as quantified by the breaking index which is now known to have no consequence on other pulsar qualities like obliquity angle evolution or complex high-order multiple structures but rather on its spin proportion. In the canonical model n=3, but observationally n≠3 in numerous cases. Showing that the canonical model requires modification. Using the Australian Telescope National Facility (ATNF). Pulsars catalog, we selected 208 pulsars with 670 glitches. We computed the breaking and observed that the breaking index is smaller for very young pulsars, which usually glitch more frequently than their older, more stable counterpart analysis. They have switched over from time and also account for over 68% of the entire glitches in our population. A regression analysis shows that spin properties of pulsars are ≥ 65% correlated with breaking index (n). Implications of this result are discussed.

Multi-band ultrathin reflective metasurface for linear and circular polarization conversion in Ku, K, and Ka bands

Linear polarization (LP) and circular polarization (CP) holds paramount importance in Ku, K, and Ka bands for satellite based communication, and remote sensing applications. Satellite based remote sensing applications face challenges like atmospheric attenuation, noise & interference, and signal degradation. Moreover, satellite based communication application demands CP in two distinct, non-adjacent frequency bands with orthogonal polarizations at greater oblique angles, considering the unpredictable incidence angles of electromagnetic (EM) waves. Addressing these challenges, an innovative metasurface polarization converter is proposed to operate efficiently across the Ku-band (13.5–18.0 GHz), K-band (18.0–26.5 GHz), and Ka-band (26.5–38.5 GHz) frequency ranges. The converter achieves left-handed circular polarization (LHCP) in the Ku- and Ka-bands within the frequency ranges of 14.57–15.65 GHz and 27.47–33.85 GHz for y-polarized incident EM waves. Additionally, it provides right-handed circular polarization (RHCP) in the K- and Ka-bands at 17.27–23.92 GHz and 35.87–38.32 GHz for y-polarized incident EM waves. The LP conversion ratio exceeds 95% in the frequency bands of 15.97–16.85 GHz, 24.70–26.65 GHz, and 34.37–35.45 GHz for y-polarized, LHCP, and RHCP incident EM waves, respectively. The metasurface exhibits robust performance up to incidence angles of 45 degrees under oblique conditions. Experimental validation using traditional board-circuit manufacturing demonstrates close agreement between measured co- and cross-polarized reflection coefficients and simulations in the 13.5–18 GHz, and 24–38.5 GHz frequency range. Thin metasurface with a thickness of only 0.64 = 0.013λo mm, the proposed design outperforms existing studies in the literature, establishing its competitive edge in terms of structure and performance.