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The study considers the inverse problem in the scattering theory in one-dimensional Schrödinger equation. The corresponding scattering matrix consists of 2 × 2 entries of meromorphic functions. We are interested to recover the potential source from certain information of the quotients of scattering coefficients that is known a priori. [ABSTRACT FROM AUTHOR]

Using the extended scattering matrix method, the authors explore the interference of edge states in the nanoribbon resonant structure with the relativistic quasiparticles in the quantum limit. By varying the chemical potential in the gated region, the structure of the junction, and the number of the scattering impurities/defects, the scattering coefficients of the edge states can be tuned efficiently. In particular, the Fabry–Pérot like interference in the present structure has been found and the phase accumulated highly depends on both the modes propagating vertically to the interface and the modes propagating along the interface. The feature is fundamentally different from the case of the conventional material where the longitudinal resonant states of the narrow constriction give rise to a clear conductance dips. These results are crucial and useful for engineering nanoelectronic devices based on the relativistic quasiparticles systems. [ABSTRACT FROM AUTHOR]

Leveraging topological properties in the response of electromagnetic systems can greatly enhance their potential. Although the investigation of singularity‐based electromagnetics and non‐Hermitian electronics has considerably increased in recent years in the context of various scattering anomalies, their topological properties have not been fully assessed. In this work, it is theoretically and experimentally demonstrated that non‐Hermitian perturbations around bound states in the continuum can lead to singularities of the scattering matrix, which are topologically nontrivial and comply with charge conservation. The associated scattering matrix poles, zeros, and pole‐zero pairs delineate extreme scattering events, including lasing, coherent perfect absorption, and absorber‐lasers. The presented framework enables a recipe for generation, annihilation, and addition of these singularities in electric circuits, with potential for extreme scattering engineering across a broad range of the electromagnetic spectrum for sensing, wireless power and information transfer, polarization control, and thermal emission devices. [ABSTRACT FROM AUTHOR]

Numerous acoustic features have been proposed as useful measures to characterize natural soundscapes, which can be employed to examine the impact of land transformation on the audible properties of a location. The extensive collection of available features demands an examination to identify the most informative and discriminative ones for a given problem. In this study, we conduct an empirical investigation into the selection of acoustic features for discriminating between highly and moderately transformed versions of four Colombian soundscapes: moorlands, coffee plantations, dry tropical forests, and pastures. We employ classical supervised feature selection techniques along with exploratory tools such as correlation matrices and scatter plots. Our results indicate that a few acoustic features are sufficient to differentiate between the classes. Specifically, those features that estimate acoustic complexity via intrinsic variability of sound intensities or biodiversity through species richness or abundance in specific frequency bands are the most discriminative ones. These Findings suggest that the selection of acoustic features can assist in analyzing and distinguishing between different soundscapes. [ABSTRACT FROM AUTHOR]

The scattering matrix is the mathematical representation of the scattering characteristics of any scatterer. Nevertheless, except for scatterers with high symmetry like spheres or cylinders, the scattering matrix does not have any analytical forms and thus can only be calculated numerically, which requires heavy computation. Here, we have developed a well-trained deep neural network (DNN) that can calculate the scattering matrix of scatterers without symmetry at a speed thousands of times faster than that of finite element solvers. Interestingly, the scattering matrix obtained from the DNN inherently satisfies the fundamental physical principles, including energy conservation, time reversal and reciprocity. Moreover, inverse design based on the DNN is made possible by applying the gradient descent algorithm. Finally, we demonstrate an application of the DNN, which is to design scatterers with desired scattering properties under special conditions. Our work proposes a convenient solution of deep learning for scattering problems. [ABSTRACT FROM AUTHOR]

During the process of the airborne synthetic aperture radar (SAR) system platform in space, platform attitude deflection is inevitable. However, large attitude deflection angles are unacceptable for polarimetric calibration using point targets, especially the dihedral, which is very sensitive to the pointing angle of the radar. To mitigate the impact of attitude angles on calibration accuracy, attitude compensation of the corner reflector is necessary during the calibration process. The conventional approach to attitude compensation typically maps the three-dimensional attitude angle information to the one-dimensional polarimetric orientation angle (POA) information. However, the reduction of dimension inevitably results in information loss, leading to errors that affect calibration performance when the attitude angle is large. In order to ensure the accuracy of point target calibration, this paper proposes a novel point target compensation method based on the reflection theory of electromagnetic waves. This method is based on three-dimensional attitude angle information and has higher reliability than the POA method. Finally, this paper calculates the distance between the scattering matrices obtained after compensation based on the proposed method and the POA method to obtain the difference in the performance of the two methods. Through a simulation, this paper finds that when the attitude angle is small, the results of the two schemes are approximately the same, but as the attitude angle increases, the error between the two gradually increases. This suggests that the proposed method has greater advantages in the case of attitude deflection. Furthermore, the proposed method does not require additional information supplementation compared with the equivalent POA method, making it highly practical. [ABSTRACT FROM AUTHOR]

The Wigner–Smith (WS) time delay matrix relates a lossless system's scattering matrix to its frequency derivative. First proposed in the realm of quantum mechanics to characterize time delays experienced by particles during a collision, this article extends the use of WS time delay techniques to acoustic scattering problems governed by the Helmholtz equation. Expression for the entries of the WS time delay matrix involving renormalized volume integrals of energy densities are derived, and shown to hold true, independent of the scatterer's geometry, boundary condition (sound-soft or sound-hard), and excitation. Numerical examples show that the eigenmodes of the WS time delay matrix describe distinct scattering phenomena characterized by well-defined time delays. [ABSTRACT FROM AUTHOR]

We study the interactions of systems of two and three nondegenerate mesons composed of pions and kaons at maximal isospin using lattice QCD, specifically π+K+, π+π+K+ and K+K+π+. Utilizing the stochastic LapH method, we determine the spectrum of these systems on two CLS Nf = 2 + 1 ensembles with pion masses of 200 MeV and 340 MeV, and include many levels in different momentum frames. We constrain the K matrices describing two- and three-particle interactions by fitting the spectrum to the results predicted by the finite-volume formalism, including up to p waves. This requires also results for the π+π+ and K+K+ spectrum, which have been obtained previously on the same configurations. We explore different fitting strategies, comparing fits to energy shifts with fits to energies boosted to the rest frame, and also comparing simultaneous global fits to all relevant two- and three-particle channels to those where we first fit two-particle channels and then add in the three-particle information. We provide the first determination of the three-particle K matrix in π+π+K+ and K+K+π+ systems, finding statistically significant nonzero results in most cases. We include s and p waves in the K matrix for π+K+ scattering, finding evidence for an attractive p-wave scattering length. We compare our results to Chiral Perturbation Theory, including an investigation of the impact of discretization errors, for which we provide the leading order predictions obtained using Wilson Chiral Perturbation Theory. [ABSTRACT FROM AUTHOR]

The main objective of this work is to isolate Effective Field Theory scattering amplitudes in the space of non-perturbative two-to-two amplitudes, using the S-matrix Bootstrap. We do so by introducing the notion of Effective Field Theory cutoff in the S-matrix Bootstrap approach. We introduce a number of novel numerical techniques and improvements both for the primal and the linearized dual approach. We perform a detailed comparison of the full unitarity bounds with those obtained using positivity and linearized unitarity. Moreover, we discuss the notion of Spin-Zero and UV dominance along the boundary of the allowed amplitude space by introducing suitable observables. Finally, we show that this construction also leads to novel bounds on operators of dimension less than or equal to six. [ABSTRACT FROM AUTHOR]

The purpose of this study is to model the characteristics (scattering matrix element |S11| and 2D and 3D radiation patterns (RPs)) of phased-array antennas (PAAs) composed of graphene-based nanoribbon elements with different numbers of emitters (N = 16, 64, and 256) and analyze their controllability under variable chemical potential (application of an external electric field) in the terahertz and far-IR frequency ranges using the CST Studio Suite 2021 software package. The characteristics (scattering matrix and 2D and 3D RPs) of a graphene antenna and a PAA composed of graphene nanoribbon elements with a different number of emitters (N = 16, 64, and 256) and the controllability of the PAA depending on the chemical potential (µc = 0.3, 0.7, and 1 eV) in the frequency range f = 6–40 THz are simulated using the CST Studio Suite 2021 software. As follows from the electrodynamic simulation results, a change in the graphene chemical potential leads to changes in the PAA characteristics (half-power main lobe width , its amplitude, side-lobe level, direction of the RP main lobe, and operating frequencies). Phased-array antennas composed of rectangular graphene nanoribbon elements can be electrically controlled with frequency scanning by changing chemical potential µc (by applying an external electric field) in the terahertz, far-IR, and mid-IR frequency ranges. [ABSTRACT FROM AUTHOR]

We investigate the chiral spectral singularities, i.e., laser threshold modes, in PT-symmetric dielectric metasurfaces originating from quasi-bound states in the continuum. The poles, referred to as the quasi-bound states in the continuum, of scattering matrix can move to the upper complex frequency plane from the lower half-plane by increasing the balanced gain and loss. The maximal intrinsic optical chirality of laser threshold mode has been theoretically demonstrated via the large transmission circular dichroism spectra. Our work paves the way for studying the enhanced optical chirality in non-Hermitian nanophotonics empowered by quasi-bound states in the continuum, together with various intriguing applications, such as chiral coherent perfect absorber and laser. [ABSTRACT FROM AUTHOR]

Space-time-coding (STC) digital metasurfaces provide a powerful platform for simultaneous spatiotemporal modulations of electromagnetic waves. Therefore, the fast and accurate generation of STC matrices based on desired harmonic scattering patterns can help STC metasurfaces enhance their practicality in various applications. Here, we propose a physics-driven vector-quantized (PD-VQ) intelligent autoencoder model that consists of an encoder, a vector-quantizer layer, and a physics-driven decoder. The physical operation mechanism between the STC matrix and the harmonic scattering pattern is introduced into the decoding module of the PD-VQ intelligent autoencoder, so that the autoencoder can be trained in an unsupervised manner without the need for large amount of manually labeled data. Taking a target harmonic scattering pattern as input, the trained PD-VQ autoencoder can quickly output the optimized discrete STC matrix, which takes only about 78 ms. We present a series of simulation examples to verify the reliability and accuracy of the proposed approach and also demonstrate its good generalization capability. Based on the proposed PD-VQ intelligent autoencoder, the STC digital metasurfaces enable agile multi-frequency harmonic beamforming. [ABSTRACT FROM AUTHOR]

Anisotropy is ubiquitous in the Earth's crust, which causes the elastic characteristics of seismic waves to change with direction. The study of seismic wave anisotropy is of great significance to seismic exploration, prediction and geodynamics. As one of the sources of seismic anisotropy, in situ stress belongs to secondary anisotropy as common as the intrinsic and fracture-induced anisotropy, but it is often ignored among the sources of seismic anisotropy. Therefore, we focus on the study of seismic anisotropy under the influence of in situ stress using the nonlinear acoustoelasticity theory. Based on a horizontal transversely isotropic (HTI) model and the linear slip theory, the characteristics of azimuthal seismic reflection response in anisotropic media under horizontal in situ stress are discussed in this paper. Firstly, by using the quasi-linear relationship between stress and Tsvankin's anisotropic parameters and the transformation relationship between anisotropic and fracture parameters in HTI medium, the elastic stiffness matrix of an HTI medium with the effect of horizontal in situ stress is established. Secondly, the reflection coefficient of PP-wave seismic data for a planar weak-contrast interface separating two weak-anisotropy and small-stress HTI half-spaces is derived using both the seismic scattering theory and the stiffness matrix under horizontal in situ stress, building the quantitative relationship between azimuthal seismic reflection characteristics and the model parameters, such as the background elastic parameters, the fracture parameters and the horizontal-stress-induced anisotropic parameters. Finally, the variation rules of azimuthal seismic reflection response characteristics of four elastic interfaces under different in situ stress conditions are analyzed. The results demonstrate that the seismic inversion for fracture parameters and horizontal-stress-induced anisotropic parameters is more favorable under the condition of large incident angle. In addition, the effect of horizontal in situ stress on the reflection coefficient depends on the second- and third-order elastic properties of the rock itself. Also, the established seismic PP-wave reflection coefficient equation has provided an alternative approach to calculate the magnitude of horizontal in situ stress. Article Highlights: A novel linearized PP-wave reflection coefficient is presented for HTI media with the effect of horizontal in situ stress The response law of azimuthal seismic reflection characteristics induced by horizontal in situ stress is demonstrated A simple inversion method is provided to calculate the magnitude of horizontal in situ stress [ABSTRACT FROM AUTHOR]

Scanning transmission electron microscopy images can be complex to interpret on the atomic scale as the contrast is sensitive to multiple factors such as sample thickness, composition, defects and aberrations. Simulations are commonly used to validate or interpret real experimental images, but they come at a cost of either long computation times or specialist hardware such as graphics processing units. Recent works in compressive sensing for experimental STEM images have shown that it is possible to significantly reduce the amount of acquired signal and still recover the full image without significant loss of image quality, and therefore it is proposed here that similar methods can be applied to STEM simulations. In this paper, we demonstrate a method that can significantly increase the efficiency of STEM simulations through a targeted sampling strategy, along with a new approach to independently subsample each frozen phonon layer. We show the effectiveness of this method by simulating a SrTiO3 grain boundary and monolayer 2H‐MoS2 containing a sulphur vacancy using the abTEM software. We also show how this method is not limited to only traditional multislice methods, but also increases the speed of the PRISM simulation method. Furthermore, we discuss the possibility for STEM simulations to seed the acquisition of real data, to potentially lead the way to self‐driving (correcting) STEM. Lay Description: Scanning Transmission Electron Microscopy (STEM) simulation is used to validate contrast in experimental images through matching procedures. Parameter searches are performed over various combinations of aberrations and sample structures until an approximation is made with respect to the experimental image. The most common approach for calculating simulations is the multislice approach, where the sample potential is approximated as a series of two‐dimensional slices. The propagation of the beam between slices involves multiple Fast Fourier Transform calculations, which must be performed at all probe locations, hence it is computationally expensive. This means that STEM multislice simulations take a significant amount time to perform, even with specialist hardware such as graphical processing units for parallelisation of calculation. An alternative to this is a recently developed algorithm known as the plane‐wave reciprocal‐space interpolated scattering matrix (PRISM) method. PRISM uses the fact that the electron probe can also be expressed as a plane‐wave expansion, and a basis set of plane‐waves can be propagated through the sample (as in the multislice step) independently of one another. After the plane‐waves are propagated through the sample, they form what is known as a scattering matrix and can be superimposed with appropriate coefficients to approximate the exit wavefunction/probe. This makes PRISM significantly faster to compute exit probes, at a small expense of accuracy with respect to the ground truth multislice simulation. In this paper, we present a novel method for increasing STEM simulation computation time through targeted probe sub‐sampling. This method takes advantage of developments within the compressive sensing (CS) community, whereby a significant proportion of probe locations can be omitted during calculation, yet inpainted through a dictionary learning and sparse coding algorithms (such as Beta Process Factor Analysis, BPFA) with minimal loss of accuracy. The method is implemented with both the PRISM and multislice algorithms, and demonstrations of the method are applied to HAADF simulations of a low energy strontium titanate grain boundary, and the 2H phase of monolayer molybdenum disulfide with sulfur vacancies. The methods yield results which are functionally identical to the ground truth (fully sampled) multislice simulations, but can be performed up to 350× faster by using the PRISM method with sub‐sampling. Furthermore, we also demonstrate how STEM simulations can seed the recovery of experimental CS‐STEM data through (dictionary) transfer learning. This is applied to sub‐sampled HAADF images of yttrium silicide, and shows a 9% increase in PSNR versus only using BPFA. [ABSTRACT FROM AUTHOR]

The asymptotic behavior of the solution of the scattering problem for three three- dimensional Coulomb quantum particles in a neighborhood of the three-particle forward scattering direction is considered. [ABSTRACT FROM AUTHOR]

A quantum pumping protocol through which the quasiparticles of Weyl/multi‐Weyl and nodal‐line semimetals are subjected to a time‐periodic rectangular potential well is considered. The presence of an oscillating potential of frequency ω creates equispaced Floquet side‐bands with spacing ℏω$\hbar \omega$. As a result, a Fano resonance is observed when the difference in the Fermi energy (i.e., the energy of the incident quasiparticle), and the energy of one of the (quasi)bound state levels of the well, coincides with the energy of an integer number of photons (each carrying energy quantum ℏω$\hbar \omega$). Using the Floquet theory and the scattering matrix approach in the zero‐temperature non‐adiabatic pumping limit, characteristic Fano resonance patterns are found in the transmission coefficients. The inflection points in the pumped shot noise spectra also serve as a proxy for the corresponding Fano resonances. Therefore, the pumped shot noise is also numerically evaluated. Finally, the existence of the Fano resonance points is correlated to the (quasi)bound states of the well, by explicitly calculating the bound states of the static well (which are a subset of the bound states of the driven system). Since semimetals with anisotropic dispersions are considered, all the features observed depend on the orientation of the potential well. [ABSTRACT FROM AUTHOR]

Exploiting topological ideas has been a major theme in modern photonics, which provides unprecedented opportunities to design photonic devices with robustness against defects. While most previous works in topological photonics have focused on band theory, recent theories extend the topological concepts to the analysis of scattering matrices and suggest a topological route to complete polarization conversion (CPC). Here, the experimental observation of the topological CPC is reported. Using angle-resolved reflection measurements, it is unveiled experimentally that the CPC between arbitrary two polarizations occurs at vortex singularities of reflection coefficients in momentum space, reflecting its topological nature. Besides, it is visualized directly that for a given input polarization, the output one can cover the entire Poincaré sphere over a wide frequency range by varying the incident angle, guaranteed by the topological nature of CPC, which is in sharp contrast to the conventional polarization-conversion approaches that usually suffer from the bulky volume, limited choice of eigen-polarization states, or narrow operation bandwidths. Remarkably, that BICs lie on the critical coupling curves that define the condition for CPC is experimentally demonstrated. This work paves the way to exploring the topological properties in scattering matrices for controlling light polarization and creating robust photonics devices. [ABSTRACT FROM AUTHOR]

Two powerful theories for state-to-state chemical reactions are brought together for the first time. The first theory incorporates Regge pole positions and residues into the partial wave (PW) scattering (S) matrix. The second theory is a 'weak' version of Heisenberg's Scattering Matrix Programme (wHSMP). It uses four general physical principles to suggest simple parameterised forms for the S matrix. The wHSMP is particularly useful for understanding generic structures in differential cross sections (DCSs). Our initial S matrix parameterisation has no Regge poles, but it exhibits a rainbow in the DCS using a Legendre PW series. We then introduce Regge poles for three examples into the S matrix and investigate their influence on the rainbow scattering. We find that inclusion of Regge poles 'pushes' the rainbow angle to larger values. We also employ Nearside-Farside (NF) PW and Local Angular Momentum PW theories, including up to three resummations. The recently introduced 'CoroGlo' test is used to distinguish between glory and corona scattering in the forward direction. We apply full and NF asymptotic (semiclassical) rainbow theories: the uniform and transitional Airy approximations for the farside scattering. We prove that structure in the no-pole and with-pole DCSs are examples of primary and supernumerary rainbows. [ABSTRACT FROM AUTHOR]

Scattering characteristic extraction is an essential part of manmade target recognition. However, if two scattering points are in adjacent pixels, scattering characteristic extraction may fail to acquire accurate polarimetric scattering matrices (PSMs) of the weak scattering points due to the contamination caused by the strong scattering points. Target null theory provides a way to solve this problem. By selecting the transmitting and receiving polarization states of radar antennas simultaneously, the echo power of a strong scattering point becomes zero and the contamination effect is avoided. In this paper, a method based on target null theory for scattering characteristic extraction is proposed. First, we optimize the transmitting and receiving polarization states of the radar antenna to suppress the intensities of the strong scattering points to highlight the positions of the weak scattering points in certain polarimetric channels. Second, to suppress the contamination effects of strong scattering points in other polarimetric channels, we establish perturbation correction equations to erase the error generated by the point spread function (PSF) among adjacent scattering points in the radar image. Finally, the solved polarimetric scattering matrices of corresponding positions are implemented for target retrieval. The electromagnetic simulation results demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

We propose analytical approximations of the reflection and transmission spectra of a stacked dielectric diffraction grating consisting of two identical resonant guided-mode gratings with a Lorentzian line shape. These approximations, derived using the scattering matrix formalism, are functions of both angular frequency ω and the tangential wave vector component k x of the incident wave. We analytically demonstrate and, using full-wave simulations with rigorous coupled-wave analysis technique, numerically confirm that by a proper choice of the thickness of the dielectric layer separating the gratings, one can tailor the resonant optical properties of the stacked structure. In particular, it is possible to obtain lines of quasi-bound states in the continuum in the ω – k x parameter space with the quality factor decaying proportionally to k x − 4 or k x − 6 . In addition, the stacked structure can be used as a spectral or spatial Butterworth filter operating in reflection. The presented results may find application in the design of optical filters and sensors based on stacked resonant gratings. [ABSTRACT FROM AUTHOR]

A wideband multiple-input multiple-output (MIMO) antenna for C-band applications is presented in this paper. It consists of 2 × 1 hexagonal motifs which serves as radiating elements. The side of each hexagonal element is 5.73 mm and the overall dimension of the proposed MIMO antenna is 30 × 20 × 1.6 mm3. The hexagonal motifs are embedded on inexpensive FR-4 lossy substrate. Thereafter, a circle with radius 1 mm is etched at the center of each hexagonal motif. Inverted L-shaped stubs are employed to attain efficient isolation between the nearby antenna elements. Four inverted L-shaped stubs are included to further enhance the isolation and eliminate the antenna size increment simultaneously, by suppressing the surface waves. Before using the decoupling approach, the MIMO antenna had an impedance bandwidth of 6.7 GHz and an isolation of −20 dB. The suggested antenna's impedance bandwidth and isolation are 5.83 GHz and −52 dB, respectively, after using a decoupling approach (inverted L-shaped stub). The proposed MIMO antenna had a peak gain and radiation efficiency of 3–7 dBi and better than 90% (with decoupling), 2.75 to 6 dBi and greater than 60% (without decoupling). To verify the proposed design, a prototype was developed to compare the simulated parameters with the measured one. The envelope correlation coefficient (ECC) was less than 0.05, and channel capacity loss (CCL) less than 0.3 was achieved with DGS. Besides, scattering matrix such as return loss S11 and transmission coefficient S21 between two elements, radiation pattern, and current distribution was also favorable. Thus, the proposed MIMO antenna is advantageous to be used for C-band applications such as developing new generation air-borne and space-borne radars, as well as X-band applications. [ABSTRACT FROM AUTHOR]

We study the nonlinear Helmholtz equation (Δ - λ²) u = ± |u|p-1 u ℝn, λ > 0, p ∈ ... odd, and more generally (Δg + V - λ²)u = N[u], where Δg is the (positive) Laplace--Beltrami operator on an asymptotically Euclidean or conic manifold, V is a short range potential, and NOEu. is a more general polynomial nonlinearity. Under the conditions (p - 1) (n - 1)/2 > 2 and k > (n - 1)/2, for every f ∈ Hk (...) of sufficiently small norm, we show there is a nonlinear Helmholtz eigenfunction taking the form ... for some b ∈ Hk(...) and ε > 0. That is, the nonlinear scattering matrix f ... b preserves Sobolev regularity, which is an improvement over the authors' previous work (2020) with Zhang, that proved a similar result with a loss of four derivatives. [ABSTRACT FROM AUTHOR]

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Understanding substrate effects on spin dynamics and relaxation is of key importance for spin-based information technologies. However, the key factors that determine such effects, in particular for materials with strong spin-orbit coupling (SOC), have not been well understood. Here we performed first-principles real-time density-matrix dynamics simulations with SOC and the electron-phonon and electron-impurity scattering for spin lifetimes (τs) of supported/free-standing germanene, a prototypical strong SOC 2D Dirac material. We show that the effects of different substrates on τs can surprisingly differ by two orders of magnitude. We find that substrate effects on τs are closely related to substrate-induced modifications of the SOC-field anisotropy, which changes the spin-flip scattering matrix elements. We propose a new electronic quantity, named spin-flip angle θ↑↓, to characterize spin relaxation through intervalley spin-flip scattering. We find that τ s − 1 is approximately proportional to the averaged value of sin 2 θ ↑ ↓ / 2 , which serves as a guiding parameter of controlling spin relaxation. [ABSTRACT FROM AUTHOR]

Calibrating the redshift distributions of photometric galaxy samples is essential in weak lensing studies. The self-calibration method combines angular auto- and cross-correlations between galaxies in multiple photometric redshift (photo- z) bins to reconstruct the scattering rates matrix between redshift bins. In this paper, we test a recently proposed self-calibration algorithm using the DECaLS Data Release 9 and investigate to what extent the scattering rates are determined. We first mitigate the spurious angular correlations due to imaging systematics by a machine learning based method. We then improve the algorithm for χ2 minimization and error estimation. Finally, we solve for the scattering matrices, carry out a series of consistency tests, and find reasonable agreements: (1) finer photo- z bins return a high-resolution scattering matrix, and it is broadly consistent with the low-resolution matrix from wider bins; (2) the scattering matrix from the Northern Galactic Cap is almost identical to that from Southern Galactic Cap; (3) the scattering matrices are in reasonable agreement with those constructed from the power spectrum and the weighted spectroscopic subsample. We also evaluate the impact of cosmic magnification. Although it changes little the diagonal elements of the scattering matrix, it affects the off-diagonals significantly. The scattering matrix also shows some dependence on scale cut of input correlations, which may be related to a known numerical degeneracy between certain scattering pairs. This work demonstrates the feasibility of the self-calibration method in real data and provides a practical alternative to calibrate the redshift distributions of photometric samples. [ABSTRACT FROM AUTHOR]

In order to improve the efficiency of breeding programs related to abiotic stresses, a new package in R-based-language, "PBTolindex," was introduced to distinguish tolerant genotypes to drought stress. Accordingly, a dataset of a practical breeding program on 30 triticale genotypes cultivated under drought stress and normal irrigation conditions in six different environments was evaluated. Correlation plot, scatter plot matrix, 3 D plot, and biplot along with indices' values and their correlation coefficients were automatically produced as output files for considering the tested genotypes. Additionally, heatmap, a novel data mining method, was successfully applied for the first time in tolerance analysis. Our results indicated that no single suitable tolerance index could be suggested as the best one, and for any other study, different indices should be considered. Furthermore, the outputs of testing triticale genotypes indicated no suitable genotypes for both conditions. However, genotype ELTTCL15 for normal condition and genotypes ET-90-7, ELTTCL21, and ELTTCL18 for stress conditions were recommended by the program. Testing and identifying genotypes by heatmap and principal component analyses showed that the output of our program was accurate. Therefore, using this source-code in future plant breeding projects based on stress indices in any plant species is recommended. [ABSTRACT FROM AUTHOR]

The polarimetric synthetic aperture radar (PolSAR) provides us with a two-by-two scattering matrix data set. The ensemble averaged coherency matrix in an imaging window derived using a scattering matrix has all non-zero elements in its three-by-three matrix. It is a full 3 × 3 matrix that bears nine real-valued and independent polarimetric parameters inside. In the proposed decomposition method, G5U, we preprocess observed coherency matrix [T] by using two consecutive unitary transformations to become an ideal form for five-component decomposition. The transformation reduces nine parameters to seven, which is the best fit for five-component scattering model expansion. We can retrieve five powers corresponding to surface scattering, double bounce scattering, volume scattering, oriented dipole scattering, and compound dipole scattering, directly. These powers can be calculated easily and used to display superb polarimetric RBG images as never before, and are further applicable for polarimetric calibration, classification, validation, etc. [ABSTRACT FROM AUTHOR]

The present study investigates the corrosion behavior of a Fe–Mn–Al–Ni–Cr shape memory alloy in a 5.0 wt% NaCl solution in combination with the functional properties. In a single crystalline condition, the investigated alloy shows a superior superelastic response with a maximum recovery strain of 5.2%. Furthermore, the results of the potentiodynamic polarization and impedance spectroscopy show that the addition of chromium generally improves corrosion resistance by increasing the resistance to localized corrosion. The single crystalline condition, which is characterized by an austenitic matrix and scattered martensite plates, shows an enhanced, however, still unstable passive behavior due to the formation of corrosion pits along the martensite plates. [ABSTRACT FROM AUTHOR]

Scattering matrices that can be diagonalized by a rotation through an angle θ in 2 × 2 blocks of independent scattering matrices of rank N, are considered. Assuming that the independent scattering matrices are chosen from one of the circular ensembles, or from the Poisson kernel, the 2 N × 2 N scattering matrix may describe the scattering through chaotic cavities with reduced symmetry in the absence, or presence, of direct processes, respectively. To illustrate the effect of such symmetry, the statistical distribution of the dimensionless conductance through a ballistic chaotic cavity in the presence of direct processes is analyzed for N = 1 using analytical calculations. We make a conjecture for N = 2 in the absence of direct processes, which is verified by numerical random-matrix theory simulations, and the first two moments are calculated analytically for arbitrary N. [ABSTRACT FROM AUTHOR]

Herein, the mechanical properties of an auto-polymerizing resin incorporated with a surface pre-reacted glass ionomer (S-PRG) filler were evaluated. For this, S-PRG fillers with particle sizes of 1 μm (S-PRG-1) and 3 μm (S-PRG-3) were mixed at 10, 20, 30, and 40 wt% to prepare experimental resin powders. The powders and a liquid (powder/liquid ratio = 1.0 g/0.5 mL) were kneaded and filled into a silicone mold to obtain rectangular specimens. The flexural strength and modulus (n = 12) were recorded via a three-point bending test. The flexural strengths of S-PRG-1 at 10 wt% (62.14 MPa) and S-PRG-3 at 10 and 20 wt% (68.68 and 62.70 MPa, respectively) were adequate (>60 MPa). The flexural modulus of the S-PRG-3-containing specimen was significantly higher than that of the S-PRG-1-containing specimen. Scanning electron microscopy observations of the specimen fracture surfaces after bending revealed that the S-PRG fillers were tightly embedded and scattered in the resin matrix. The Vickers hardness increased with an increasing filler content and size. The Vickers hardness of S-PRG-3 (14.86–15.48 HV) was higher than that of S-PRG-1 (13.48–14.97 HV). Thus, the particle size and content of the S-PRG filler affect the mechanical properties of the experimental auto-polymerizing resin. [ABSTRACT FROM AUTHOR]

Recent advances in electron microscopy allowed the generation of high-energy electron wave packets of ultrashort duration. Here we present a non-perturbative S -matrix theory for scattering of ultrashort electron wave packets by atomic targets. We apply the formalism to a case of elastic scattering and derive a generalized optical theorem for ultrashort wave-packet scattering. By numerical simulations with 1 fs wave packets, we find in angular distributions of electrons on a detector one-fold and anomalous two-fold azimuthal asymmetries. We discuss how the asymmetries relate to the coherence properties of the electron beam, and to the magnitude and phase of the scattering amplitude. The essential role of the phase of the exact scattering amplitude is revealed by comparison with results obtained using the first-Born approximation. Our work paves a way for controlling electron-matter interaction by the lateral and transversal coherence properties of pulsed electron beams.

Recent theories and experiments have explored the use of entangled photons as a spectroscopic probe of physical systems. We describe here a theoretical description for entropy production in the scattering of an entangled biphoton Fock state within an optical cavity. We develop this using perturbation theory by expanding the biphoton scattering matrix in terms of single-photon terms in which we introduce the photon-photon interaction via a complex coupling constant, ξ. We show that the von Neumann entropy provides a concise measure of this interaction. We then develop a microscopic model and show that in the limit of fast fluctuations, the entanglement entropy vanishes, whereas in the limit of slow fluctuations, the entanglement entropy depends on the magnitude of the fluctuations and reaches a maximum. Our result suggests that experiments measuring biphoton entanglement give microscopic information pertaining to exciton-exciton correlations. [ABSTRACT FROM AUTHOR]

In some real applications, it requires to recognize known class(es) as well as unknown class. Traditional classification can only recognize the known class(es) which occur(s) in the training set. Recently, Kernel Null Foley-Sammon Transformation (KNFST) is proposed to overcome the weakness that traditional classification cannot identify unknown class. In KNFST, the samples from the same class are mapped to a point via null projected directions. For a test sample, the predicted label is the class with the minimum distance to it in the projected space. If the test sample is far away from all projected points, it comes from an unknown class. However, KNFST only considers the global information which is depicted by between- and within- class scatter matrices. When the internal structure is complex, KNFST may fail. In order to handle this issue, this paper proposes a Kernel Null Regularized Foley-Sammon Transformation (KNRFST) by introducing a regularized term into KNFST. The regularized term is depicted by a neighborhood which consists of reverse nearest neighbors. The neighborhood can depict the local information in the class. The experimental results, performed on several datasets, show that KNRFST is superior to some previous methods, including KNFST, Local KNFST, WOC-SVM, Deep SVDD and OCC-GAN. [ABSTRACT FROM AUTHOR]

Synthetic aperture radar with polarimetric diversity is a powerful tool in remote sensing. Each pixel is described by the scattering matrix corresponding to the emission/reception polarization states (usually horizontal and vertical). The algebraic real representation, a block symmetric matrix form, is introduced to adopt a more comprehensive framework (non-restricted by reciprocity assumptions) in mapping the scattering matrix by the consimilarity equivalence relation. The proposed representation can reveal potentially new information. For example, its eigenvalue decomposition, which is itself a necessary step in obtaining the consimilarity transformation products, may be useful in characterizing the degree of reciprocity/nonreciprocity. As a consequence, it can be employed in testing the reciprocity compliance assumed with monostatic PolSAR data. Full-wave simulated polarimetric data confirm that oriented scatterers can present complex eigenvalues, even with the monostatic geometry. [ABSTRACT FROM AUTHOR]

Most global aerosol models approximate dust as spherical particles, whereas most remote sensing retrieval algorithms approximate dust as spheroidal particles with a shape distribution that conflicts with measurements. These inconsistent and inaccurate shape assumptions generate biases in dust single-scattering properties. Here, we obtain dust single-scattering properties by approximating dust as triaxial ellipsoidal particles with observationally constrained shape distributions. We find that, relative to the ellipsoidal dust optics obtained here, the spherical dust optics used in most aerosol models underestimate dust single-scattering albedo, mass extinction efficiency, and asymmetry parameter for almost all dust sizes in both the shortwave and longwave spectra. We further find that the ellipsoidal dust optics are in substantially better agreement with observations of the scattering matrix and linear depolarization ratio than the spheroidal dust optics used in most retrieval algorithms. However, relative to observations, the ellipsoidal dust optics overestimate the lidar ratio by underestimating the backscattering intensity by a factor of ∼2. This occurs largely because the computational method used to simulate ellipsoidal dust optics (i.e., the improved geometric optics method) underestimates the backscattering intensity by a factor of ∼2 relative to other computational methods (e.g., the physical geometric optics method). We conclude that the ellipsoidal dust optics with observationally constrained shape distributions can help improve global aerosol models and possibly remote sensing retrieval algorithms that do not use the backscattering signal. [ABSTRACT FROM AUTHOR]

We relate the scattering theory of the focusing AKNS system with vanishing boundary conditions to that of the matrix Schrödinger equation. The corresponding Miura transformation, which allows this connection, converts the focusing matrix nonlinear Schrödinger (NLS) equation into a new nonlocal integrable equation. We apply the matrix triplet method to derive the multisoliton solutions of the nonlocal integrable equation, thus proposing a new method to solve the matrix NLS equation. [ABSTRACT FROM AUTHOR]

Considerable research has been devoted to the development of cathode materials for Al-ion batteries, but challenges remain regarding the behavior of aluminum anodes. Inert oxide (Al2O3) film on Al surfaces presents a barrier to electrochemical activity. The structure of the oxide film needs to be weakened to facilitate ion transfer during electrochemical activity. This study addresses oxide film challenges by studying Al alloy anodes with different iron content. The results reveal that using an anode of 99% Al 1% Fe in a cell increases the cycling lifetime by 48%, compared to a 99.99% Al anode. The improvement observed with the 99% Al 1% Fe anode is attributed to its fractional surface area corrosion being about 12% larger than that of a 99.99% Al anode. This is coupled to precipitation of a higher number of Al3Fe particles, which are evenly scattered in the Al matrix of 99% Al 1% Fe. These Al3Fe particles constitute weak spots in the oxide film for the electrolyte to attack, and access to fresh Al. The addition of iron to an Al anode thus offers a cheap and easy route for targeting the oxide passivating film challenge in Al-ion batteries. [ABSTRACT FROM AUTHOR]

We discuss a method of analysis of symmetric electromagnetic components with magnetic media based on magnetic group theory. In this description, some of the irreducible corepresentations assume complex values exp (i θ) with the real parameter θ. A possible physical interpretation of this parameter is given. We demonstrate the application of the symmetry-adapted linear combination method combined with the corepresentation theory to the problem of current modes in an array of magnetized graphene elements where Faraday and Kerr effects can exist. The elements are described by the magnetic symmetry C 4 or C 4 v (C 4) . The scattering matrix of the array and its eigensolutions are defined and analyzed and some numerical simulations are presented as well. An example of a waveguide described by symmetry C 4 v (C 2 v) with a specific type of degeneracy is also discussed. [ABSTRACT FROM AUTHOR]

This paper presents a new facial feature extraction method on entropy based fractional fuzzy generalized two-dimensional linear discriminant analysis (EnFFG-2DLDA) where the concept of class uncertainty is incorporated within the generalized two-dimensional linear discriminant analysis. The EnFFG-2DLDA achieves the optimal projection matrix (in both directions) by maximizing the entropy and fuzzy membership value, based on inter-class similarity, while minimizing intra-class discrepancy by integrating weight function. This method ameliorates the shortcomings of 2DLDA method, which fails in case of many real-world situations as it focuses on the global relationship of data, and relies on Gaussian distributed data. Our EnFFG-2DLDA method does not depend on the assumptions that the data distributions and it exploits the intrinsic local structure of the data. Moreover, the FkNN has been incorporated into G-2DLDA algorithm to highlight distinguishable features by redefining the intra- (within) and inter- (between) class scatter matrices along horizontal (row) and vertical (column) directions. The global and per-class mean training vectors are regenerated by combining the fuzzy membership values. The weighting function is associated into inter class scatter matrix, in both direction, to solve contour based problem. Finally, Entropy membership values are specifically used for measuring uncertainty in the special variation in a facial image. Therefore, more significant feature information have been distilled out by combining FkNN, weight function and entropy with the G-2DLDA method, which solves the multi-classification problem. The feasibility of fractional fuzzy G-2DLDA with entropy membership value has been validated over frontal, occluded, and rotationally- angled images with four public standard face databases using RBF neural network. The investigational results demonstrate the substantial accuracy of 99.06% (k = 6) for ORL, 97.81% (k = 10) for UMIST and 66.04 (k = 4) for FERET dataset in terms of average recognition accuracy. [ABSTRACT FROM AUTHOR]

The interferometric synthetic aperture radar (InSAR) technique based on time–frequency (TF) analysis has great potential for mapping the forest canopy height model (CHM) at regional and global scales, as it benefits from the additional InSAR observations provided by the sublook decomposition. Meanwhile, due to the wider swath and higher spatial resolution of single-polarization data, InSAR has a higher observation efficiency in comparison with PolInSAR. However, the accuracy of the CHM inversion obtained by the TF-InSAR method is attenuated by its inaccurate coherent scattering modeling and uncertain parameter calculation. Hence, a new approach for CHM estimation based on single-baseline InSAR data and sublook decomposition is proposed in this study. With its derivation of the coherent scattering modeling based on the scattering matrix of sublook observations, a time–frequency based random volume over ground (TF-RVoG) model is proposed to describe the relationship between the sublook coherence and the forest biophysical parameters. Then, a modified three-stage method based on the TF-RVoG model is used for CHM retrieval. Finally, the two-dimensional (2-D) ambiguous error of pure volume coherence caused by residual ground scattering and temporal decorrelation is alleviated in the complex unit circle. The performance of the proposed method was tested with airborne L-band E-SAR data at the Krycklan test site in Northern Sweden. Results show that the modified three-stage method provides a root-mean-square error (RMSE) of 5.61 m using InSAR and 14.3% improvement over the PolInSAR technique with respect to the classical three-stage inversion result. An inversion accuracy of RMSE = 2.54 m is obtained when the spatial heterogeneity of CHM is considered using the proposed method, demonstrating a noticeable improvement of 32.8% compared with results from the existing method which introduces the fixed temporal decorrelation factor. [ABSTRACT FROM AUTHOR]

This study reports the development of tangent-linear and adjoint models for a vector radiative transfer model called TAMU-VRTM. This vector radiative transfer model is further validated in the case of the atmosphere–ocean coupled system, although previous validation was conducted for single and multiple layers. The TAMU-VRTM and tangent-linear and adjoint models can be applied to remote sensing and data assimilation based on spaceborne and airborne polarimetric observations. The tangent-linear and adjoint models accurately and efficiently compute the derivatives of output Stokes parameters with respect to input variables of the TAMU-VRTM. An inversion algorithm can straightforwardly compute the Jacobian matrix from the derivatives of Stokes parameters using the chain rule. We validate the tangent-linear and adjoint models by comparing them with the finite-difference method, and show that the finite-difference results converge to the tangent-linear and adjoint results. Furthermore, the adjoint model can efficiently compute the derivatives of observables with respect to the scattering phase matrix elements. This capability can be used to evaluate the scattering phase matrix assumed in an inversion algorithm and has potential for applications to inferring scattering phase matrix elements of cloud, aerosol, and hydrosol particles. [ABSTRACT FROM AUTHOR]

A scattering matrix method is applied to investigate propagation characteristics of oblique incident terahertz waves into magnetized dusty plasmas. The numerical results agree well with those given by the Wenzell–Kramer–Brillouin method. Three different electron density distributions are taken into account, and both the right- and left-hand circularly polarized (RCP and LCP) waves are analyzed. Transmission properties of terahertz (THz) waves with different physical parameters, such as external magnetic, dust particle density, and dust particle radius, are discussed systematically. There exists a transmissivity peak at the lower-frequency band for RCP waves when an external magnetic field is presented. The value of the peak nearly keeps invariant, and its location moves toward the higher-frequency direction if the magnetic field enhances. Increasing the dust particle density or radius can make the value of a transmissivity peak larger. The transmissivity of higher-frequency RCP THz waves decreases if the external magnetic field increases. However, for LCP waves, there is no transmissivity peak. It increases monotonously as the frequency of a THz wave increases. Different from the RCP waves, enhancing the external magnetic field is better for the LCP waves to penetrate the dusty plasma. Our results may provide some theoretical basis for alleviating the problem of "blackout." [ABSTRACT FROM AUTHOR]

In this article, we present a miniaturized wideband multiple-input multiple-output antenna with high isolation for C band use. It consists of 2×1 hexagonal motifs which serves as radiating elements. Defected ground structure (DGS) technique is employed to attain an efficient isolation between the antenna elements. Two inverted L-shaped stubs are incorporated to enhance the isolation and reduce the antenna size enlargement simultaneously, by suppressing the surface waves. The overall dimension of the designed MIMO antenna is 30 × 20 mm2. The proposed DGS structure provides - 40.81 dB of isolation at 7.88 GHz and a gap of 4 mm between adjacent antenna elements. Envelope correlation coefficient (ECC) is less than 0.01, diversity gain (DG) greater than 9.95 dB, total active reflection coefficient (TARC) less than 0.4, mean effective gain (MEG) less than -3 dB, and channel capacity loss (CCL) less than 0.4 is achieved. Besides, scattering matrix such as return loss S11 and transmission coefficient S21 between two elements, radiation pattern, and current distribution was also favorable for Cband and X-band applications. [ABSTRACT FROM AUTHOR]

We calculate the fully retarded one-photon exchange interaction potential between electrically neutral, identical atoms, one of which is assumed to be in an excited state, by matching the scattering matrix (S matrix) element with the effective Hamiltonian. Based on the Feynman prescription, we obtain the imaginary part of the interaction energy. Our results lead to precise formulas for the distance-dependent enhancement and suppression of the decay rates of entangled superradiant and subradiant Dicke states (Bell states), as a function of the interatomic distance. The formulas include a long-range tail due to entanglement. We apply the result to an example calculation involving two hydrogen atoms, one of which is in an excited P state. [ABSTRACT FROM AUTHOR]

Optical analog computing has recently sparked growing interest due to the appealing characteristics of low energy consumption parallel processing and ultrafast speed, spawning it complementary to conventional electronic computing. As the basic computing unit, optical logic operation plays a pivotal role for integrated photonics. However, the reported optical logic operations are volumetric and single-functional, which considerably hinders the practical cascadability and complex computing requirement. Here, we propose an on-chip combinational optical logic circuit using inverse design. By precisely engineering the scattering matrix of each small-footprint logic gate, all basic optical logic gates (OR, XOR, NOT, AND, XNOR, NAND, and NOR) are realized. On this foundation, we explore the assembly of these basic logic gates for general purpose combinational logic circuits, including optical half-adder and code converter. Our work provides a path for the development of integrated, miniaturized, and cascadable photonic processor for future optical computing technologies. [ABSTRACT FROM AUTHOR]

The species-level response of organisms to habitat loss and fragmentation relies on their dispersal ability, as well as trophic level, degree of habitat specialization and landscape structure. For butterflies, community composition is affected by the landscape configuration, by the surrounding habitat and by the matrix composition scattered around forest fragments, whereas higher dispersal ability is a significant advantage for persistence in highly fragmented landscapes. However, species of butterflies are highly variable in their dispersion capabilities, which affects their genetic variability as a whole and in how it is distributed within and between subpopulations in remaining fragments. In the present study, the genetic variability in subpopulations of Paryphthimoides poltys distributed through forest fragments was evaluated. Low diversity and the absence of genetic structure was found through eight fragments of semideciduous Atlantic Forest, surrounded by agricultural matrices, in Southeastern Brazil. Although P. poltys was the most common species found in the area in a previous study, its high abundance was not accompanied by high genetic variability. The species is usually found flying in forest edges and open environments and, although low, its genetic variability is expected to be preserved even if some of the investigated forest fragments are lost in the near future. [ABSTRACT FROM AUTHOR]