Incident Mode Research Articles

Mode of transport, genetic susceptibility, and incidence of coronary heart disease

BackgroundCar use has been associated with higher risk of coronary heart disease (CHD). However, whether the associations of transport modes with CHD vary by genetic susceptibility to CHD are unknown. This study aims to investigate the associations of genetic susceptibility and modes of transport with incidence of CHD.MethodsWe included 339,588 white British participants from UK Biobank with no history of CHD or stroke at baseline or within two years of follow-up (52.3% in work). Genetic susceptibility to CHD was quantified through weighted polygenic risk scores derived from 300 single-nucleotide polymorphisms related to CHD risk. Categories of transport mode included exclusive car use and alternatives to the car (e.g., walking, cycling and public transport), separately for non-commuting (e.g., getting about [n=339,588] excluding commuting for work), commuting (in the sub-set in work [n=177,370] who responded to the commuting question), and overall transport (transport mode for both commuting and non-commuting [n=177,370]). We used Cox regression with age as the underlying timescale to estimate hazard ratios (HR) of CHD (n=13,730; median 13.8-year follow-up) and tested the interaction between genetic susceptibility and travel modes with adjustment for confounders.ResultsCompared to those using alternatives to the car, hazards of CHD were higher for exclusive use of cars for overall transport (HR: 1.16, 95% confidence interval (CI): 1.08-1.25), non-commuting (HR: 1.08, 95% CI: 1.04-1.12) and commuting (HR: 1.16, 95% CI: 1.09-1.23), after adjusting for confounders plus genetic susceptibility. HRs of CHD were 1.45 (95% CI: 1.38-1.52) and 2.04 (95% CI: 1.95-2.12) for the second and third tertile of genetic susceptibility to CHD, respectively, compared to the first. There was, in general, no strong evidence of interactions between genetic susceptibility and categories of overall, non-commuting and commuting transport. Estimated 10-year absolute risk of CHD was lower for the alternatives to the car across strata of genetic susceptibility, compared with exclusive use of cars for overall, non-commuting and commuting transport.ConclusionExclusive use of cars was associated with a relatively higher risk of CHD across all strata of genetic susceptibility. Using alternatives to the car should be encouraged for prevention of CHD for the general population including individuals at high genetic risk.

Maximum directivity of flanged open-ended waveguides

Directional beams have extensive applications in communication and sound reproduction. This paper investigates the theoretical maximum directivity of infinitely flanged open-ended waveguides and the radiation pattern synthesis. We derive a rigorous solution for the maximum directivity factor of a flanged aperture with arbitrary shape by projecting its surface velocity on the waveguide modes, enabling the creation of a directional beam in any desired direction. We present case studies for a three-dimensional circular waveguide and a bidimensional waveguide. The theoretical beam that is obtained in a subspace spanned by all the propagating modes can then be synthesized by a group of incident modes or a point-source array within the waveguide. The optimality of the beam is demonstrated by comparing it with Gaussian shaded modes radiated from the waveguide. If the evanescent modes are taken into account, the maximum directivity factor increases with considerable loss to the radiation efficiency. Nevertheless, the optimum aperture velocity dominated by its evanescent components is capable of precise beam steering in extreme directions and could be useful for designing material-filled horns. Our work provides benchmark directivity factors and patterns for the practical design of horn antennas. In addition, we present a generalized form of Bouwkamp's impedance theorem.

Investigations on asymmetric transmittivity of optical devices and different diode-like behaviors

This study theoretically proved that although reciprocal optical devices can show asymmetric transmittivity (AT) under controlled incident modes (i.e., conditional AT), they cannot guarantee AT with arbitrary incident light modes, whereas only nonreciprocal optical devices can possibly guarantee AT. Besides, the thermodynamics of both reciprocal and nonreciprocal optical devices were discussed to show that the second law of thermodynamics is valid anyway. Furthermore, the diode-like behaviors of optical and electronic devices were compared. Electrons are identical to electronic devices, so electronic devices could have asymmetric conductance regardless of electrons. In contrast, electromagnetic waves are different from optical devices as transmittivity of different modes can be different, so reciprocal optical devices showing conditional AT cannot guarantee AT when incident modes are arbitrary. The mathematical proof and characteristic comparisons between electronic and optical diodes, which are firstly presented here, should help clarifying the necessary nonreciprocity required for being optical diodes.

Polarization Scattering Properties of Inhomogeneous Plasma-Covered Metal Plate

The plasma sheath generated during the reentry of the hypersonic vehicle will significantly influence the amplitude and polarization property of the scattered wave and lead to abnormal scattering characteristics of the hypersonic vehicle. Therefore, an electromagnetic (EM) simulation model of 3-D inhomogeneous plasma-covered metal plate is deployed to study the scattered properties of linear polarization plane wave obliquely incident on the inhomogeneous plasma. Based on the dispersive media’s convolutional perfect matched layer (CPML) and taking the Gaussian pulse linear polarization wave as an example, this article studies the effects of the plasma parameters, including the electron density and the collision frequency, on the scattered properties of plasma covered metal plate. Then, the influences of incident angle and EM wave polarization mode on the polarization properties of the scattered wave are emphatically analyzed. Numerical results indicate that the inhomogeneous plasma presents the cross-polarization isolation effect when the electric field of the plane wave is parallel to the surface of the plasma. On the contrary, the inhomogeneous plasma presents the cross-polarization depolarization effect when the electric field vector intersects with the surface of the plasma. The results provide a theoretical basis for the research on radar cross section (RCS) measurement, polarization matching, and EM stealth of plasma-sheath-covered hypersonic vehicles.

The role of evanescent modes in global-local analysis of ultrasonic guided waves in plates with varying local zone-scatterer relations

In order to provide a reliable and robust SHM performance, Ultrasonic Guided Waves (UGWs) need to be analyzed and understood. Numerical modeling of UGW propagation and scattering by hybrid methods offers the possibility of simulating UGW interaction with waveguides of arbitrary cross-sections and discontinuities. Maximizing the accuracy of such methods is important to perform quantitative SHM, while maintaining minimum computational cost. This work investigates the role of evanescent modes in the numerical analysis of UGWs in aluminum and composite plates with defects, by the hybrid Global-Local method. The complex solutions to the UGW eigenvalue problem are found and the scattering spectra for A0 and S0 incident modes are calculated. The accuracy of the numerical solution is then studied by computing the error in terms of energy balance. Parametric studies with respect to the local zone size, defect dimensions and shape are conducted including and excluding evanescent modes in the analysis. Considerations are provided to obtain a solution with error no greater than 5%, in terms of varying local zone – scatterer relations within plate waveguides.

FDTD investigation of cylindrical waveguides with azimuthal corrugations excited by axisymmetric TE modes

In this work we investigated the scattering parameters and mode conversion of axisymmetric TE modes in smooth cylindrical waveguides with wedge-shaped azimuthal corrugations. In particular, we studied the effect of the length of the corrugated region on the scattering parameters and on the mode conversion. The field distribution was derived by the FDTD code COCHLEA and further post-processed using the COPP code. Results showed that the incident mode is converted to an ensemble of modes, the azimuthal indices of which are given by the SHM criterion. Azimuthal corrugated waveguides are usually employed in the gyrotron beam-tunnel to enhance the suppression of the parasitic modes.

A Boundary Integral Method for 3-D Nonuniform Dielectric Waveguide Problems via the Windowed Green Function

This communication proposes an efficient boundary-integral-based “windowed Green function” (WGF) methodology for the numerical solution of 3-D general electromagnetic problems containing dielectric waveguides. The approach, which generalizes a recently introduced 2-D version of the method, provides a highly effective solver for such problems. In particular, using an auxiliary integral representation, the proposed method is able to accurately model incident mode excitation. On the basis of a smooth window function, the integral operators along the infinite waveguide boundaries are smoothly truncated, resulting in errors that decay faster than any negative power of the window size.

Effect of Oblique SV Wave on the Seismic Response of Mountain Tunnel

In order to study the dynamic response of parallel mountain tunnels under the oblique incidence of seismic waves, based on the display finite element method and using viscoelastic artificial boundary, the oblique incidence of three-way seismic waves was realized by angular incident mode. The displacement and stress distribution characteristics of the tunnel lining under different propagation angles and vibration angles of SV waves were studied. The results show that the oblique incidence of SV wave has a certain effect on the displacement of the double tunnel, the forces in the tunnel are symmetrical and the axis displacement increases with the increase of incident angle, and the vertical displacement changes greatly. The stress of the tunnel lining under the oblique incidence of the SV wave is elliptical. The peak value of the maximum principal stress appears at the maximum span on both sides, and the maximum principal stress decreases with the increase of the vibration angle. The maximum principal stress of the right tunnel is flat. The minimum principal stress of the left and right holes decreases with the increase of vibration angle, and the minimum principal stress of the left hole is 90°∼270°. The distribution of the minimum principal stress in the range is large. Mises stress increases with the increase of the incidence angle of seismic waves.

Polarization Scattering Characteristic of Plasma-Sheath-Covered Hypersonic Vehicle

The plasma sheath covering the vehicle’s surface will be generated during the reentry of the hypersonic vehicle, which has a complex modulation effect on the electromagnetic (EM) wave and significantly affects the scattering characteristics of the hypersonic vehicle. This article analyzes the backward polarization scattering characteristics of a plasma-sheath-covered hypersonic vehicle. Based on the plasma sheath parameters at typical heights and velocities solved by numerical simulation, the current density convolution method was used to simulate the interaction between the linearly polarized plane EM wave and the hypersonic vehicle. Two backward far-field scattered components (co- and cross-polarization) are obtained using transient field extrapolation. Through studying the cross_polarization isolation (XPI) of scattering EM waves, this article analyzes the influences of flight status, EM waves’ incident angles, polarization modes (vertical and horizon), and frequency range on the backward radar cross Section (RCS) of hypersonic vehicles.

Noise reduction by perforated cascades in annular ducts

One of the latest trends in noise control relating to aeroacoustics is to mimic the silent flight capability of owls. Particularly, porosity is most often applied on cascades in ducts with axial flows, such as stator structures in an aero-engine. However, current acoustic scattering models of perforated cascades are based on two-dimensional methods without including the three-dimensional effects. In this paper, we present a fully three-dimensional acoustic scattering model for perforated cascades based on the lifting surface theory in which the dominant sound source reduces to dipoles alone under the thin airfoil assumption. Accordingly, the acoustic scattering of perforated cascades with single-mode incident wave was studied and obvious noise reduction was observed. The optimum Rayleigh conductivity and the maximum noise-reducing capability of the porosity varied substantially with different incident duct modes, whilst a larger cascade chord-length could achieve more noise reduction at optimum porosity. With a background flow, the Kutta condition can greatly influence the overall distribution of the unsteady loading on vanes. Additionally, the unsteady vortex shedding at the trailing edge offers extra sound energy dissipation mechanism. Therefore, the implementation of porosity on cascades is much different to the design of a traditional acoustic liner.

8.56-GHz quasi-optical launcher system with incident-mode selectivity on the QUEST spherical tokamak

An 8.56-GHz quasi-optical launcher system with incident-mode selectivity was developed for non-inductive electron cyclotron (EC) plasma ramp-up and long-pulse sustainment, and effective bulk-electron heating on the Q-shu University experiment with steady-state spherical tokamak (QUEST). A novel polarization-selective system was proposed to conduct fundamental and second harmonic EC heating and current drive experiments with ordinary and extra-ordinary mode waves, respectively. Selectivity of the incident modes or polarizations was confirmed using the whole developed system at a low power level. A large-sized mirror launcher was developed to inject the beam whose size was as small as possible near the QUEST major radius. The designed mirror performance was checked using a three-dimensional electromagnetic-wave simulator and a low-power test. Ultimately, 0.15-m sized beams for both the two polarizations were successfully attained near the QUEST major radius, even in low-frequency applications with long propagation.

Bragg scattering of flexural-gravity waves by a series of polynyas in the context of blocking dynamics

Flexural-gravity wave scattering due to an array of polynyas is investigated from the perspective of the blocking dynamics. The canonical eigenfunction expansion method is generalized to account for multiple propagating wave modes within blocking frequencies. Bragg scattering occurs due to the presence of multiple gaps in the floating ice sheet, and the number of sub-harmonic peaks in wave reflection becomes one/two less than the number of gaps as the reflection coefficient varies with a change in gap/ice-sheet length. In addition, the amplitudes of harmonic peaks in wave reflection increase with an increase in the number of gaps. The variation of wave reflection with an increase in wavenumber/length of the ice sheet depicts that common zero minima occur for an even number of gaps, while common sub-harmonic maxima occur for an odd number of gaps. The scattering coefficients vary between zero and unity within the blocking frequencies, despite the individual amplitudes of the scattered waves becoming more than unity for certain frequencies. Noticeably, higher amplitudes of the scattered waves are associated with lower energy transfer rates and vice versa. Extrema in wave reflection occur for higher values of frequency within the primary and secondary blocking points. In addition, removable discontinuities are found in the scattering coefficient at the blocking frequencies, whereas a jump discontinuity is observed for certain frequencies within the blocking limits due to the incident wave mode conversion. Moreover, irregularities in the ice sheet's deflection are observed for any frequency within the blocking limit due to the superposition of three propagating wave modes.

Anomalous transmission and Anderson localization for alternating propagated and evanescent waves at the deep-subwavelength scale.

Deep-subwavelength features have a minimal impact on wave transport in all dielectric systems; thus the homogenization approach was commonly adopted. Recently, the breakdown of effective medium theory (EMT) for the incident wave near the total reflection (TR) angle was demonstrated in a deep-subwavelength dielectric multilayer. Additionally, anomalous transmission was reported at angles exceeding the TR angle when introducing disorder and was attributed to Anderson localization. Here we firstly demonstrated that the alleged anomalous transmission also occurs in the disorder-free case, illustrating that attributing anomalous transmission to Anderson localization deserves a more in-depth study. To clarify the underlying physics of this asserted anomalous transmission, Anderson localization and broken EMT, the incident angle dependent reflectivity and modes for ordered and disordered deep-subwavelength multilayers were investigated systematically. Actually, the EMT is still convincing and the anomalous transmission is reasonable after a simple correction. However, the anomalous transmission is more accessible and the permittivity correction is more imperative in the disordered system due to the Anderson localization. These findings can be expanded to other wave systems such as acoustic waves and matter waves, providing insight into EMT and deepening our understanding of the intriguing transport phenomena in deep subwavelength systems.

Global Dynamics Analysis of a Cholera Transmission Model with General Incidence and Multiple Modes of Infection

Global Dynamics Analysis of a Cholera Transmission Model with General Incidence and Multiple Modes of Infection

Changing trends in the global burden of mental disorders from 1990 to 2019 and predicted levels in 25 years.

The burden of mental disorders is increasing worldwide, thus, affecting society and healthcare systems. This study investigated the independent influences of age, period and cohort on the global prevalence of mental disorders from 1990 to 2019; compared them by sex; and predicted the future burden of mental disorders in the next 25years. The age-specific and sex-specific incidence of mental disorders worldwide was analysed according to the general analysis strategy used in the Global Burden of Disease Study in 2019. The incidence and mortality trends of mental disorders from 1990 to 2019 were evaluated through joinpoint regression analysis. The influences of age, period and cohort on the incidence of mental disorders were evaluated with an age-period-cohort model. From 1990 to 2019, the sex-specific age-standardized incidence and disability-adjusted life years (DALY) rate decreased slightly. Joinpoint regression analysis from 1990 to 2019 indicated four turning points in the male DALY rate and five turning points in the female DALY rate. In analysis of age effects, the relative risk (RR) of incidence and the DALY rate in mental disorders in men and women generally showed an inverted U-shaped pattern with increasing age. In analysis of period effects, the incidence of mental disorders increased gradually over time, and showed a sub-peak in 2004 (RR, 1.006 for males; 95% CI, 1.000-1.012; 1.002 for women, 0.997-1.008). Analysis of cohort effects showed that the incidence and DALY rate decreased in successive birth cohorts. The incidence of mental disorders is expected to decline slightly over the next 25years, but the number of cases is expected to increase. Although the age-standardized burden of mental disorders has declined in the past 30years, the number of new cases and deaths of mental disorders worldwide has increased, and will continue to increase in the near future. Therefore, relevant policies should be used to promote the prevention and management of known risk factors and strengthen the understanding of risk profiles and incidence modes of mental disorders, to help guide future research on control and prevention strategies.

Theoretical design of multilayered VO2-based switchable terahertz metasurfaces as broadband functional devices

In this paper, a switchable terahertz metasurface based on VO2 multilayer structure is raised, which utilizes the temperature phase-transition properties of VO2 to achieve the functions of switchable polarization conversion and reflection phase modulation for arbitrarily polarized waves at different temperatures. The simulation results show that at high-temperature and low-temperature, the metasurface develop a resonant system to achieve polarization conversion for circularly polarized (CP) and linearly polarized (LP) waves, respectively. For the conversion of the CP wave at high-temperature, the polarization conversion rate exceeds 90% in the terahertz frequency range of 1.01 ∼ 2.00 THz, and at low-temperature, the polarization conversion of the LP wave reaches a near-perfect polarization conversion rate at frequencies ν = 0.65, 1.07, and 1.50 THz. Arbitrary phase regulation can be achieved by rotating the VO2 strips and altering the geometry of the C-shaped split resonator ring (CSRR) to form a periodic array with a constant gradient phase. In order to verify that the device has the function of wavefront phase modulation, we use the device to simulate the abnormal reflection based on the generalized Snell’s law.Additionally, we generated a bifocal focused beam within a cross-channel in LP incidence mode using the propagation phase principle.

Response characteristics and tensile failure evaluation of asphalt concrete core wall under spatial oblique incidence of P-wave

The research on asphalt concrete core embankment dam under the spatial oblique incidence of seismic wave and the dynamic tensile failure of the core is still insufficient. This paper considers the spatial arbitrariness of P-wave incident azimuth angle γ and oblique incident angle α, constructs the non-uniform free field on the foundation boundary based on the wave field superposition principle, and establishes a wave input method for P-wave oblique-incidence in three-dimensional space. Then, an empirical formula for the change in the instantaneous tensile strength of asphalt concrete with the strain rate is established on the basis of the test results. Furthermore, a new core safety evaluation method based on instantaneous tensile stress and strength is proposed to discriminate element tensile failure. Finally, the influence law of incident azimuth and oblique incident angles on the acceleration and stress spatial distribution of asphalt concrete core is analyzed. The damage mechanism of the core caused by the surge of local tensile stress caused by spatial oblique incidence is revealed. The traditional static strength discrimination method has an error in discriminating the core failure compared with the method proposed in this paper. The distribution characteristics of tensile weak zone and failure zone of the core under different incident modes are clarified. Results show that compared with the vertical incident, the core accelerations in the water flow and dam axis directions increased by a maximum of 9.6 times and 68% under spatial oblique incidence (γ ∈ [0°, 90°] and α∈(0°, 75°]), and the core acceleration in the vertical direction can be reduced by 69%. The core compressive and tensile stresses increased by a maximum of 31.3% and 4.0 times under spatial oblique incidence (γ ∈ [0°, 90°] and α∈(0°, 75°]). Neglecting spatial oblique incidence will underestimate the core accelerations and stresses seriously. The more the incident direction deviates to the dam axis and the larger the oblique incident angle is, the more prone it is to tensile failure on the wave-facing side of the core. When the incident direction is consistent with the dam axis and the incident angle is 75°, the tensile failure on the wave-backing side of the core is more serious than that on the wave-facing side. The use of the traditional static strength discrimination method will result in the large crack failure error of the core.

Radio-frequency sheath excitation at the extremities of scrape-off layer plasma filaments, mediated by resonant high harmonic fast wave scattering

Resonant filament-assisted mode conversion (FAMC) scattering of high harmonic fast waves (HHFW) by cylindrical field-aligned density inhomogeneities can efficiently redirect a fraction of the launched HHFW power flux into the parallel direction. Within a simplified analytic approach, this contribution compares the parallel propagation, reflection and dissipation of nearly resonant FAMC modes for three magnetic field line geometries in the scrape-off layer, in the presence of radio-frequency (RF) sheaths at field line extremities and phenomenological wave damping in the plasma volume. When a FAMC mode, excited at the HHFW antenna parallel location and guided along the open magnetic field lines, impinges onto a boundary at normal incidence, we show that it can excite sheath RF oscillations, even toroidally far away from the HHFW launcher. The RF sheaths then dissipate part of the power flux carried by the incident mode, while another part reflects into the FAMC mode with the opposite wave vector parallel to the magnetic field. The reflected FAMC mode in turn propagates and can possibly interact with the sheath at the opposite field line boundary. The two counter-propagating modes then form in the bounded magnetic flux tube a lossy cavity excited by the HHFW scattering. We investigate how the presence of field line boundaries affects the total HHFW power redirected into the filament, and its splitting between sheath and volume losses, as a function of relevant parameters in the model.

축대칭 반사모드 특성 규명 및 배관 결함검출

The converted modes generated by mode conversion in guided waves-based inspection can provide plenty of defect information, and the reasonable usage of multiple wave modes can improve the results of defect inspection and evaluation. This paper focuses on the inter-conversion process of axisymmetric modes for incident longitudinal modes when interacting with the defects in pipeline whilst ignoring the converted non-axisymmetric modes through suppressing them in reception. This process is defined as symmetric mode conversion in this research. The pattern of axisymmetric mode sequence during symmetric conversion is identified and the method is proposed to extract the converted axisymmetric mode components for analysis. The relationships between the defect features and the modes generated in symmetric mode conversion under the excitation of longitudinal mode waves are investigated. The results show that longitudinal modes in symmetric mode conversion provide the potential for establishing an effective defect inspection.

The law of blast stress wave propagation and fracture development in soft and hard composite rock

The process of blasting stress wave propagation and crack propagation is directly affected by the physical properties of the rock mass and internal joints in the rock. In soft and hard rock layers, the blasting process is more complicated since the blasting stress wave needs to penetrate two kinds of rocks with different physical properties and the interface between soft rock and hard rock. In this study, the modal transformation of stress waves at the interface of layered composite rock was analyzed, and the process was reproduced by finite element analysis. Furthermore, the development law of cracks was explored. The research results demonstrated that in the single blasting-hole model, a triangular crack area caused by reflected stress waves appeared at the rock interface of rock medium I near the blast hole. In rock medium II, the tensile crack generated by the interface wave appeared on the side away from the blast hole. Besides, the development of the tensile crack was associated with the incident mode of the blast stress wave and the incident angle. In the deep hole blasting model, the incidence of the detonation wave front from hard rock to soft rock promoted the fragmentation of the hard rock.