Pairs Of Patches Research Articles

Synchronization within synchronization: transients and intermittency in ecological networks

Transients are fundamental to ecological systems with significant implications to management, conservation and biological control. We uncover a type of transient synchronization behavior in spatial ecological networks whose local dynamics are of the chaotic, predator–prey type. In the parameter regime where there is phase synchronization among all the patches, complete synchronization (i.e. synchronization in both phase and amplitude) can arise in certain pairs of patches as determined by the network symmetry—henceforth the phenomenon of ‘synchronization within synchronization.’ Distinct patterns of complete synchronization coexist but, due to intrinsic instability or noise, each pattern is a transient and there is random, intermittent switching among the patterns in the course of time evolution. The probability distribution of the transient time is found to follow an algebraic scaling law with a divergent average transient lifetime. Based on symmetry considerations, we develop a stability analysis to understand these phenomena. The general principle of symmetry can also be exploited to explain previously discovered, counterintuitive synchronization behaviors in ecological networks.

A compact printed ultra-wideband filtenna with low dispersion for WiMAX and WLAN interference cancellation

A printed monopole filtenna fed by a co-planar waveguide with U-shaped split slot on patch and circular split ring resonator pairs at the other side of feed is proposed in this letter. The compact filtenna of dimension 0.32λ × 0.215λ (λ denotes wavelength corresponding to 2.68 GHz) is capable of providing large bandwidth from 2.68 to 8.72 GHz with dual frequency notch bands over 3.28–3.84 and 4.95–6.02 GHz, primarily to eliminate the WiMAX and WLAN interferences. The dual notched antenna performances are evaluated by simulation and experimental measurement and compared to those of recently reported ultra-wideband (UWB) notched antennas. The proposed filtenna provides bidirectional E-plane and omni-directional H-plane radiation patterns with gain variation of 2–4.5 dBi and average radiation efficiency of 78% in its pass band. Also the filtenna offers minimal dispersion characteristic as stable group delay response, and linear variation of transfer function (S21) is achieved in its pass bandwidth.

A Wide-Beam Antenna for Wide-Angle Scanning Linear Phased Arrays

In this letter, a wide-beam (at two main planes) antenna is proposed. To broaden the 3 dB beamwidth of the original antenna, a pair of parasitic patches with metallic vias is creatively arranged on either side of the original radiation patches. Based on the proposed antenna element, two linear phased arrays are fabricated and measured. Measured results reveal that the wide-angle scanning capability of both H -plane and E -plane arrays can be obtained. The scanning beam of the former can cover territories ranging from −90° to 90°, with gain loss within 3 dB (8 GHz–11 GHz). The scanning beam of the latter can cover territories ranging from −70° to 70°, with gain loss of 3–5 dB (8 GHz–10 GHz).

A compact wideband circularly polarized antenna with two pairs of driven patch arrays

In this article, a new wideband circularly polarized (CP) antenna is presented. The antenna is composed of a circular-loop feeding structure which provides sequential phase (SP), four primary-parasitic crown patches and four secondary-parasitic crown patches. The circular-loop SP structure is used to feed the two pairs of crown patches by a capacitively coupled way. The presented antenna features a wide 10-dB impedance bandwidth (IBW) of 23% (6 GHz, 5.31-6.69 GHz), and a wide 3-dB axial ratio bandwidth (ARBW) of 11.1% (5.875 GHz, 5.55-6.2 GHz). The proposed antenna features compact structure and broad 3 dB-ARBW, which could include the WLAN (5.725-5.85 GHz), ITS (5.8 GHz), and WIFI (5.85-5.925 GHz) band.

Collaborative Attention-Based Heterogeneous Gated Fusion Network for Land Cover Classification

Existing land cover classification methods mostly rely on either the optical or synthetic aperture radar (SAR) features alone, which ignore the mutual complementary effects between optical and SAR sources. In this article, we compare the distribution histograms of deep semantic features extracted from optical and SAR modalities within land cover categories, which intuitively demonstrates that there are the large complementary potentials between the optical and SAR features. Therefore, we propose a novel collaborative attention-based heterogeneous gated fusion network (CHGFNet), which hierarchically fuses both optical and SAR features for land cover classification. More specifically, the CHGFNet consists of three main components: two-stream feature extractor, multimodal collaborative attention module (MCAM), and the gated heterogeneous fusion module (GHFM). Given optical and SAR patch pairs, two-stream feature extractor introduces multistage feature learning methodology to acquire discriminative optical and SAR features. Then, to explore the inherent complementarity between optical and SAR features, MCAM is embedded into CHGFNet, which provides an efficient stage to capture the correlation between optical and SAR features by jointly calculating the collaborative attention in joint feature space. Finally, to automatically learn the varying contributions of both optical and SAR features for classifying different land categories, GHFM is used to fuse both optical and SAR features. Extensive comparative evaluations demonstrate the advantages of CHGFNet within land cover classification over the state-of-the-art methods on three co-registered optical and SAR data sets.

Design of a wideband substrate integrated waveguide antenna with high‐gain employing two bow‐tie‐shaped slots

In this work, a compact antenna employing the substrate integrated waveguide (SIW) technology is investigated to achieve the characteristics of wideband and high gain. A pair of novel elliptical patches, which operate as an electric dipole, are loaded on the upper surface of the antenna. Two bow-tie-shaped slots are etched in parallel on the upper surface of SIW to obtain the features of magneto dipole and wideband. Combined with the low profile character of the SIW, the low cost of printed circuit board technology and the broadband characteristic of magneto-electric (ME) dipole, a 1 × 8 SIW ME-dipole antenna array is proposed and fabricated. The experimental result of the proposed prototype shows that the 10 dB impedance bandwidth is 42.3% from 19.4 to 29.8 GHz, which is basically consistent with the simulated result. Moreover, the antenna gain up to 14.6 dBi and the radiation efficiency higher than 82.6% are also obtained during the experiment. In the whole resonance band, excellent directional radiation, cross-polarisation level <−25 dB and gain fluctuation <2.7 dB all suggest that the array can be applied to a fifth-generation wireless network.

DEEP LEARNING BASED FEATURE MATCHING AND ITS APPLICATION IN IMAGE ORIENTATION

Abstract. Matching images containing large viewpoint and viewing direction changes, resulting in large perspective differences, still is a very challenging problem. Affine shape estimation, orientation assignment and feature description algorithms based on detected hand crafted features have shown to be error prone. In this paper, affine shape estimation, orientation assignment and description of local features is achieved through deep learning. Those three modules are trained based on loss functions optimizing the matching performance of input patch pairs. The trained descriptors are first evaluated on the Brown dataset (Brown et al., 2011), a standard descriptor performance benchmark. The whole pipeline is then tested on images of small blocks acquired with an aerial penta camera, to compute image orientation. The results show that learned features perform significantly better than alternatives based on hand crafted features.

Morphological evolution in Hyles Hübner, 1819 hawkmoths (Lepidoptera, Sphingidae): reconstructing the ancestral Hyles habitus

Molecular phylogenetic studies suggest that similar wing and body patterns in the hawkmoth genus Hyles Hübner, [1819] do not necessarily reflect a close phylogenetic relationship. To improve our understanding of morphological evolution in these organisms, 75 characters derived from the external adult morphology are explicitly coded and analysed in a maximum parsimony cladistic framework. The results corroborate the hypothesis that wing and body patterns have indeed reappeared in different parts of the phylogeny but the underlying genetic mechanism remains to be determined. By reconstructing the suite of ancestral states of the morphological characters using Bayesian inference, we derived an approximation of the appearance of the proto-Hyles species. The overall habitus of this moth does not display a combination of characters found in any extant Hyles species. Rather, the forewings are most like those of members of the Hyles euphorbiae-complex but with better developed antemedial and postmedial lines, the hindwings are typical Hyles, and the abdominal pattern most closely resembles that of Hyles euphorbiarum (Guérin-Méneville &amp;amp; Percheron, 1835), but with one fewer pairs of black subdorsal patches. Within the context of the subtribe Choerocampina and Sphingidae more generally, the proto-Hyles reconstruction does not resemble any other species apart from Rhodafra opheltes (Cramer, 1780), but this appears to be another instance of convergent pattern expression.

Compact Patch Antenna With Vertical Polarization and Omnidirectional Radiation Characteristics

This communication proposes a compact, low-profile patch antenna with omnidirectional radiation pattern and vertical polarization. A pair of shorted patches are excited in-phase to achieve the omnidirectivity and the vertical polarization, simultaneously. The principle is to excite two back-to-back arranged shorted patches to generate symmetrical electric-field (E-field) distributions normal to the ground plane. Analytical study on how to generate the omnidirectional radiation pattern is carried out. Based on this study, we found that the spacing in between the two patches have little influence on the radiation characteristics, which provides another flexibility in the design. In addition, the shape of the patch and the corresponding field distribution are investigated to further improve the omnidirectivity. To improve the impedance bandwidth, resonant structures are inserted in between the patches, producing the second-order response in frequency. The antenna has been fabricated and characterized, and the measured results are in reasonable agreement with the simulations, showing that the proposed antenna is suitable for potential surface-mount wireless applications.

Strip-pair comparison method for building threshold color-difference model: theoretical model validation.

This paper presents a method for developing color-difference models near a threshold, based on the serial exploration method described by Torgerson [Theory and Methods of Scaling; Wiley & Sons (1958); Chap. 7], involving the construction of color-control strips of patches arranged in arrays of 2 × n, where n is the number of pairs in the strip. The patches in the lower row should be calorimetrically identical, while the color of the patches in the upper row should vary progressively in constant steps of CIELAB color difference along selected color space vector directions. Prospective observers are instructed to indicate the patch pair number for which they begin to perceive a slight color difference between corresponding patches. The frequency data obtained from the observers was used to build a threshold color-difference model. The intention was to validate the method with theoretical data to determine the effect of the precision with which the strips are constructed, on the accuracy of the estimated parameters. Theoretical frequency data was generated using the CIE94 color difference formula, whose associated color discrimination ellipsoid parameters are very easy to determine, associated with a hypothetical logistic psychometric curve for different color centers. The proposed method allows to determine color discrimination parameters with a precision nearby 4% and an accuracy of 3% with respect to the simulated theoretical parameters, for color samples generated with a standard deviation of ΔEab∗=0.2 of the superimposed error around the ideal color difference of pairs of patches.

Parametric effects by using the strip-pair comparison method around red CIE color center.

The strip comparison method, based on the serial exploration method described by Torgerson [Theory and Methods of Scaling; Wiley & Sons (1958); Chap. 7], for the development of near-threshold color difference models was presented and validated with theoretical data by the authors in a previous work. In this study, we investigate parametric effects derived from the use of the strip comparison method on chromaticity-discrimination ellipses around the red CIE color center. The results obtained led to the conclusion that the strip comparison method has little effect on the parameters of the chromaticity-discrimination ellipses determined by the pair comparison method when pairs of patches in the strips are separated by a black line 0.5 mm thick or are separated by 3 mm spacing on a white background and also correlates well with the parameters reported by other authors using the pair comparison method at the threshold.

New broadband circularly polarized antenna with an inverted F‐shaped feedline

In this article, we present a new broadband CP square-slot antenna with an inverted F-shaped feed-line. The antenna is composed of an inverted F-shaped feed-line, pairs of isosceles triangular chamfers, I-shaped slots, rectangular slots and triangular patches, and a Z-shaped strip. By introducing these strips and slots into the square-slot, multiple CP modes can be stimulated simultaneously, which eventually enhances 3-dB ARBW and 10-dB impedance bandwidth (IBW) of the presented antenna. The measured results show that its IBW (|S11| < −10 dB) is about 7.2 GHz (87.8% from 4.6 to 11.8 GHz) and its ARBW (AR < 3 dB) is 8.3 GHz (96% from 4.5 to 12.8 GHz).

Optimal Network Architectures for Spatially Structured Populations with Heterogeneous Diffusion.

The motivation of this article is to derive new management guidelines to maximize the overall population size using popular management and conservation strategies, such as protected marine areas and ecological corridors. These guidelines are based on the identification of the network architectures for which the total population size is maximized. Describing the biological roles of the typical network variables in the fate of the population is a classic problem with many practical applications. This article suggests that the optimal network architecture relies heavily on the degree of mobility of the population. The recommended network architecture for populations with reduced mobility (in the absence of cost of dispersal and landscapes made up of many sources) is a graph with a patch that has routes toward any other patch with a lower growth rate. However, for highly mobile populations there are many possible network architectures for which the total population size is maximized (e.g., any cyclic graph). We have paid special attention to species with symmetric movement in heterogeneous landscapes. A striking result is that the network architecture does not have any influence on the total population size for highly mobile populations when any pair of different patches can be connected by a sequence of paths.

Image interpolation with adaptive k ‐nearest neighbours search and random non‐linear regression

Learning-based image interpolation methods have been proved to be effective in image interpolation. In this study, the authors propose an accurate image interpolation with adaptive k-nearest neighbour searching and non-linear regression. The proposed method aims to find k-nearest neighbours of the input image patch and use them to learn the non-linear mapping between low-resolution and high-resolution image patches. To be specific, they first divide the training image patches into many subspaces, then they utilise an adaptive robust and precise k nearest neighbour searching scheme with proposed normalised Gaussian similarity to find the k nearest neighbours in the matched subspace. The selected k image patch pairs are then used to learn the non-linear regression model through an extreme learning machine. Furthermore, the proposed interpolation method is a cascade framework that consists of two stages. Stage 2 takes the results of Stage 1 as input to further improve the performance. Extensive experimental results on commonly used test images and image datasets indicate that their proposed algorithm obtains competitive performance against the state-of-the-art methods both in terms of objective evaluation values and the subjective effect of reconstructed images.

Surface–Surface-Intersection Computation Using a Bounding Volume Hierarchy with Osculating Toroidal Patches in the Leaf Nodes

We present an efficient and robust algorithm for computing the intersection curve of two freeform surfaces using a Bounding Volume Hierarchy (BVH), where the leaf nodes contain osculating toroidal patches. The covering of each surface by a union of tightly fitting toroidal patches greatly simplifies the geometric operations involved in the surface–surface-intersection computation, i.e., the bounding of surface normals, the detection of surface binormals, the point projection from one surface to the other surface, and the intersection of local surface patches. Moreover, the hierarchy of simple bounding volumes (such as rectangle-swept spheres) accelerates the geometric search for the potential pairs of surface patches that may generate some curve segments in the surface–surface-intersection. We demonstrate the effectiveness of our approach by using test examples of intersecting two freeform surfaces, including some highly non-trivial examples with tangential intersections. In particular, we test the intersection of two almost identical surfaces, where one surface is obtained from the same surface, using a rotation around a normal line by a smaller and smaller angle θ=10−k degree, k=0,…,5. The intersection results are often given as surface subpatches in some highly tangential areas, and even as the whole surface itself, when θ=0.00001∘.

Multiobjective optimization solutions for noise reduction in composite sandwich panels using active control

In this paper, optimal solutions for noise reduction in laminated viscoelastic soft core sandwich plates are obtained, using active control with surface bonded piezoelectric sensors and actuators. An in–house finite element implementation of the active laminated sandwich plate is used to obtain the frequency response of the panels. Since the structural/acoustic problem is lightly coupled, the sound transmission characteristics of the panels are evaluated by computing their radiated sound power, using the Rayleigh integral method. A negative velocity feedback control law has been used to implement the active damping. The optimal location of the surface co-located pairs of piezoelectric patches is then obtained, using the Direct MultiSearch (DMS) optimization algorithm to minimize simultaneously the added weight, the number of controllers and noise radiation. The minimization of noise radiation is accomplished by minimizing the total length of the radiated sound power frequency response curve. Trade-off Pareto fronts and the respective optimal active patch configurations are obtained and discussed.

Experimental validation of piezoelectric shunt tuning with residual mode correction: Damping of plate-like structures

The effective vibration mitigation properties of piezoceramic patches with inductive-resistive shunts are investigated experimentally. A shunt tuning method is proposed, in which a consistent correction for the influence from residual vibration modes is included by an effective modal capacitance, evaluated from measured charge and voltage amplitudes in short- and open-circuit conditions, respectively. The robustness of the proposed method is verified experimentally for both a free beam and a free plate structure with four shunted piezoceramic patch pairs. A stable and fully passive inductor is produced by winding a copper wire around a magnetic core, which requires precise inductance tuning to determine the final number of turns. It is demonstrated that the effective modal capacitance interpolates consistently between the blocked and static capacitances, commonly used for single-mode tuning of piezoelectric inductive-resistive shunts. By imposing pseudo-random vibrations, the piezoelectric current and voltage signals are measured and evaluated by their frequency response functions. Spectrum peak values determine the apparent short-circuit charge to open-circuit voltage ratio for each shunt, which directly determines the shunt components by explicit tuning formulas. Good correlation between numerical and experimental results are obtained for the free beam, while for the free plate experiment effective multi-mode shunt tuning is obtained by a modified effective electromechanical coupling coefficient.

Pan-sharpening via multi-scale and multiple deep neural networks

Interpreting remote sensing images by combining manual visual interpretation and computer automatic classification and recognition is an important application of human–computer interaction (HCI) in the field of remote sensing. Remote sensing images with high spatial resolution and high spectral resolution is an important basis for automatic classification and recognition. However, such images are often difficult to obtain directly. In order to solve the problem, a novel pan-sharpening method via multi-scale and multiple deep neural networks is presented. First, the non-subsampled contourlet transform (NSCT) is employed to decompose the high resolution (HR)/low resolution (LR) panchromatic (PAN) images into the high frequency (HF)/low frequency (LF) images, respectively. For pan-sharpening, the training sets are only sampled from the HF images. Then, the DNN is utilized to learn the feature of the HF images in different directions of HR/LR PAN images, which is trained by the image patch pair sampled from HF images of HR/LR PAN images. Moreover, in the fusion stage, NSCT is also employed to decompose the principal component of initially amplified LR multispectral (MS) image obtained by the transformation of adaptive PCA (A-PCA). The HF image patches of LR MS, as the input data of the trained DNN, go through forward propagation to obtain the output HR MS image. Finally, the output HF sub-band images and the original LF sub-band images of LR MS image fuse into a new sub-band set. The inverse transformations of NSCT and A-PCA , residual compensation are conducted to obtain the pan-sharpened HR MS. The experimental results show that our method is better than other well-known pan-sharpening methods.

Inverse halftoning through structure-aware deep convolutional neural networks

The primary issue in inverse halftoning is removing noisy dots on flat areas and restoring image structures (e.g., lines, patterns) on textured areas. Hence, a new structure-aware deep convolutional neural network that incorporates two subnetworks is proposed in this paper. One subnetwork is for image structure prediction while the other is for continuous-tone image reconstruction. First, to predict image structures, patch pairs comprising continuous-tone patches and the corresponding halftoned patches generated through digital halftoning are trained. Subsequently, gradient patches are generated by convolving gradient filters with the continuous-tone patches. The subnetwork for the image structure prediction is trained using the mini-batch gradient descent algorithm given the halftoned patches and gradient patches, which are fed into the input and loss layers of the subnetwork, respectively. Next, the predicted map including the image structures is stacked on the top of the input halftoned image through a fusion layer and fed into the image reconstruction subnetwork such that the entire network is trained adaptively to the image structures. The experimental results confirm that the proposed structure-aware network can remove noisy dot-patterns well on flat areas and restore details clearly on textured areas. Furthermore, it is demonstrated that the proposed method surpasses the conventional state-of-the-art methods based on the deep convolutional neural network, U-Net, and locally learned dictionaries.

Magnetic Connectivity between the Light Bridge and Penumbra in a Sunspot

Abstract A light bridge is a prominent structure commonly observed within a sunspot. Its presence usually triggers a wealth of dynamics in a sunspot and has a lasting impact on sunspot evolution. However, the fundamental structure of light bridges is still not well understood. In this study, we used the high-resolution spectropolarimetry data obtained by the Solar Optical Telescope on board the Hinode satellite to analyze the magnetic and thermal structure of a light bridge at AR 12838. We also combined the high-cadence channel data provided by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory to study the dynamics on this bridge. We found a pair of blue and red Doppler shift patches at two ends of this bridge; this pattern appears to be the convective motion directed by the horizontal component of the magnetic field aligned with the spine of the bridge. Paired upward and downward motions imply that the light bridge could have a two-legged or undulating magnetic field. Significant 4 minute oscillations in the emission intensity of the bandpass were detected at two ends, which overlapped the paired blue- and redshift patches. The oscillatory signals at the light bridge and the penumbra were highly correlated with each other. Although they are separated in space at the photosphere, the periodicity seems to have a common origin from underneath the sunspot. Therefore, we infer that the light bridge and penumbra could share a common magnetic source and become fragmented at the photosphere by magnetoconvection.