Patch Structure Research Articles

Attractivity analysis on a neoclassical growth system incorporating patch structure and multiple pairs of time-varying delays

In this paper, we focus on the global dynamics of a neoclassical growth system incorporating patch structure and multiple pairs of time-varying delays. Firstly, we prove the global existence, positiveness and boundedness of solutions for the addressed system. Secondly, by employing some novel differential inequality analyses and the fluctuation lemma, both delay-independent and delay-dependent criteria are established to ensure that all solutions are convergent to the unique positive equilibrium point, which supplement and improve some existing results. Finally, some numerical examples are afforded to illustrate the effectiveness and feasibility of the theoretical findings.

Design and Implementation of UWB Slot-Loaded Printed Antenna for Microwave and Millimeter Wave Applications

In this paper, single-layer ultra-Wide Band (UWB) microstrip patch antennas loaded with asymmetrical U-shaped slot in both microwave and millimeter wave applications are presented. These novel antennas cover a fractional bandwidth around 40% in both microwave and millimeter applications. The applications cover the C-band (4-8) GHz, V-band (40-75) GHz, and W-band (75-110) GHz. In addition to that, it is the sole article that cover the bands (5.15-5.825) GHz and (8.025-8.4) GHZ for WiMaX and ITU band applications, respectively. Moreover, it covers three bands for Automotive radar applications within (71-76) GHz, (81-86) GHz, and (92-95) GHz, in addition to further 5G/mm-wave applications at 60 GHz. Each antenna is coaxial fed and implemented on a Roger 5880 substrate with relative dielectric constant of 2.2, thickness of $1.575~mm$ and loss tangent of 0.0009. They operate over the frequency band (5.5-9.5) GHz for microwave band and (55-95) GHz for mm-wave band. To achieve either a notch in other bands or develop a multi-band structure, the conventional ground is replaced by two different structures. The first ground is an array of patches and the other is a mushroom ground. The first ground results in a notch within the band (73-79) GHz while the second one achieves a multi-band within (55-68) GHz and (81-95) GHz. Both antennas are simulated and verified using Finite Difference Time-Domain analysis (FDTD); CST Microwave Studio and Finite Element Method (FEM); Ansoft HFSS. For microwave band, the antenna is fabricated and measured for verification. Concerning the mm-wave version, three different types of ground planes are presented; traditional, periodic structure of patches and mushroom. The structure with periodic patches conducts the same band as the traditional ground plane does. This is a prestep for the design of the notches. The mushroom ground is carried out for multi-band applications. The average gain of the antennas is 7 dB.The measured two dimensional cuts of the radiation pattern, radiation efficiency, and reflection coefficient of the microwave version are presented and are in good agreement with the simulated results while for the mm-wave antenna the same parameters are simulated with two different methods and are in good agreement.

A corner truncated fractal slot ultrawide spectrum sensing antenna for wireless cognitive radio sensor network

SummaryDue to the scarcity of the radio frequency spectrum, the emergent network sharing technique elicits the efficient use of licensed unutilized spectrum. Here, an ultra‐wideband (UWB) microstrip antenna is proposed for wireless cognitive radio sensor network (WCRSN). The antenna is uniquely designed for large spectrum scanning of channel vacancies in licensed frequency bands. Software‐defined radios (SDR) govern the algorithmic controls on spectrum sensing and channel interface using an appropriate antenna. The antenna comprises the effects of fractal slot patch and electromagnetic bandgap (EBG) ground structures on 12 × 18 × 1.6 mm3 FR4 (relative dielectric constant of 4.4) substrate. Circular polarization is achieved through corner truncation to make antenna orientation free in wireless sensing networks. The measured |S11| parameter offers 0.75‐ to 12‐GHz wide spectrum sensing with 2.51‐dBi average gain. The antenna is unique in compactness and includes lower edge bands of frequencies (0.75–3.1 GHz) along with UWB (3.1–12.0 GHz) for a very wide range scanning to utilize vacant channel opportunity in WCRSN through SDR. The proposed structure is experimented and validated for real‐time wideband scanning of the frequency spectrum within the operating limit as per the allotted FCC standard.

Sex-biased topography effects on butterfly dispersal

BackgroundMetapopulation persistence in fragmented landscapes is assured by dispersal of individuals between local populations. In this scenario the landscape topography, although usually neglected, may have an important role in shaping dispersal throughout the matrix separating habitat patches. Due to inter-sexual differences in optimal reproductive strategies, i.e., males maximizing the number of mating opportunities and females maximizing the offspring survival chances, topography-related constraints are expected to exert a different effect on male and female dispersal behaviour. We tested sex-biased topography effects on butterfly dispersal, with the following hypotheses: (1) females are constrained by topography in their movements and avoid hill crossing; (2) male dispersal is primarily driven by two-dimensional spatial structure of the habitat patches (i.e. their geometric locations and sizes) and little influenced by topography.MethodsFollowing intensive mark-recapture surveys of Maculinea (= Phengaris) nausithous and M. teleius within a landscape characterised by an alternation of hills and valleys, we investigated sex-specific patterns in their inter-patch movement probabilities derived with a multi-state recapture model. In particular, we (1) analysed the fit of dispersal kernels based on Euclidean (= straight line) vs. topography-based (= through valley) distances; (2) compared movement probabilities for the pairs of patches separated or not by topographic barriers; and (3) tested the differences in the downward and upward movement probabilities within the pairs of patches.ResultsEuclidean distances between patches proved to be a substantially stronger predictor of inter-patch movement probabilities in males, while inter-patch distances measured along valleys performed much better for females, indicating that the latter tend to predominantly follow valleys when dispersing. In addition, there were significantly lower probabilities of movements across hills in females, but not in males.ConclusionsBoth above results provide support for the hypothesis that topography restricts dispersal in females, but not in males. Since the two sexes contribute differently to metapopulation functioning, i.e., only female dispersal can result in successful (re)colonisations of vacant patches, the topography effects exerted on females should be considered with particular attention when landscape management and conservation actions are designed in order to maintain the functional connectivity of metapopulation systems.

Simetrik Olarak Yerleştirilmiş Dairesel Boşluklara Dayalı 24-28 GHz bant 5G Anten Tasarımı

5G (fifth generation) cellular system is expected to work in a wide frequency range to meet the demand for mobile services and applications. Antennas will be addressed to the future 5G applications should pose superior characteristics, such as high gain and ultra-large bandwidth response by considering atmospheric absorption/free-space path loss on planned millimeter-wave frequency range of 5G communications. Therefore, antenna design for the future 5G applications is a challenging process. In this article we present a high-gain, broadband mm-Wave antenna based on a circular patch structure with a ground plane and resonator gaps. The designed antenna is analyzed using a widely used full-wave electromagnetic solver. The major antenna figure-of-merits including reflection coefficient, VSWR (voltage-standing wave ratio), antenna patterns in E- and H-planes, surface current distribution, antenna directivity and maximum gain, are obtained. The simulation results show that the gapped circular patch based design has the S11 response less than −10 dB in the frequency range of 21.6-28.8 GHz, which includes 24-28 GHz band of 5G cellular systems. Moreover, it is observed that the symmetrically located circular gaps on both top and bottom layers decrease the side lobe level under −10 dB value, and enhance the gain. We attribute the improvement in the antenna performance to the created current regions due to gaps hosting large vortex current distributions. With 10 mm × 13mm surface area, the proposed antenna demonstrates the peak gain of 9.44 dBi and the radiation efficiency of over 85%. High gain and compact size make this antenna suitable for coming 5G devices.

Stability for patch structure Nicholson’s blowflies systems involving distinctive maturation and feedback delays

ABSTRACT This article explores a class of patch structure Nicholson’s blowflies systems involving nonlinear density-dependent mortality terms and multiple pairs of distinctive maturation and feedback delays. By utilising the fluctuation lemma and differential inequality techniques, a delay-dependent criterion on the global asymptotic stability of the addressed systems is established, which refines and complements some existing ones. In addition, the numerical simulations verify the efficacy and accuracy of the obtained findings.

Optimization of UHF RFID Five-Slotted Patch Tag Design Using PSO Algorithm for Biomedical Sensing Systems.

In this paper, a new flexible wearable radio frequency identification (RFID) five-shaped slot patch tag placed on the human arm is designed for ultra-high frequency (UHF) healthcare sensing applications. The compact proposed tag consists of a patch structure provided with five shaped slot radiators and a flexible substrate, which minimize the human body’s impact on the antenna radiation performance. We have optimized our designed tag using the particle swarm optimization (PSO) method with curve fitting within MATLAB to minimize antenna parameters to achieve a good return loss and an attractive radiation performance in the operating band. The PSO-optimized tag’s performance has been examined over the specific placement in some parts of the human body, such as wrist and chest, to evaluate the tag response and enable our tag antenna conception in wearable biomedical sensing applications. Finally, we have tested the robustness of this tag by evaluating its sensitivity as a function of the antenna radiator placement over the ground plane or by shaping the ground plane substrate for the tag’s position from the human body. Our numerical results show an optimal tag size with good matching features and promising read ranges near the human body.

Dual Band Notch, Compact, Low profile Hybrid Ultra Wideband RDRA

This paper presents a novel, compact Ultra Wide Band , Asymmetric Ring Rectangular Dielectric Resonator Antenna (ARRDRA), which is a unique combination of Thin Dielectric Resonator (DR), Fork shape patch and defective ground structure. The base of the proposed antenna is its Hybrid structure, which generates fundamental TM, TE and higher order modes that yields an impedance bandwidth of 119%. Proposed antenna provides a frequency range from 4.2 to 16.6 GHz with a stable radiation pattern and low cross polarization levels. Peak gain of 5.5 dB and average efficiency of 90% is obtained by the design. Antenna is elongated on a FR4 substrate of dimension 20 x 24x 2.168 mm3 and is particularly suitable for C band INSAT, Radio Altimeter, WLAN, Wi-Fi for high frequencies. Ease in fabrication due to simplicity, compactness, stable radiation pattern throughout the entire bandwidth are the key features of the presented design. Inclusion of Defective ground structure and asymmetric ring not only increases the bandwidth but also stabilize the gain and efficiency due to less surface current. Presented design launch an Ultra Wide Band antenna with sufficient band rejection at 4.48-5.34 and 5.64-8.33 GHz with stable radiation pattern and high gain.

Structural repair of wind turbine blades: Computational model for the evaluation of the effect of adhesive properties

AbstractThree‐dimensional (3‐D) finite element models of structural (scarf) repair of wind turbine blade, including the composite patch, adhesive, coating and parent composite structures is developed. Computational studies of the effect of the scarf angle, thickness of the adhesive layer and the availability of voids in the adhesive on the stress field in the repaired structure were carried out. It is observed that the soft adhesives lead to increased stresses in the parent laminate structures. The availability of voids in the adhesive leads to local stress concentration, and thus can reduce the postrepair reliability of the blades.

Return loss-bandwidth evaluation for electrically small microstrip antennas

A method incorporating Bode–Fano integrals is proposed in this paper to evaluate the potential bandwidth of small antennas and provide a particular strategy for bandwidth improvement. The Bode–Fano theory is applied to the equivalent circuit of small microstrip antennas to calculate the maximum achievable return loss-bandwidth. Results of applying this theory to three types of microstrip antennas in mode of propagation with defected ground structure (DGS) and defected microstrip structure (DMS) indicate that creating slots on the microstrip patch or ground structure despite their advantages can decrease the potential bandwidth of the antenna. Fano integrals reveal the invariant relation between maximum achievable return loss-bandwidth and overall volume of the antenna validated using the quality factor (Q factor) analysis.

Semicircular shape hybrid reconfigurable antenna on Jute textile for ISM , Wi‐Fi , Wi‐MAX , and W‐LAN applications

This article presents the development of a conformal reconfigurable frequency circularly polarized jute textile antenna, working at 2.4, 3.5, 5.8, and 5.9 GHz in Wi-Fi, Wi-MAX, Industrial, Scientific and Medical radio bands and W-LAN. The antenna topology is based on a semicircular structure as the main radiating component. The conductivity is realized by using copper paint, which was brush-painted. The patch structure is rehashed in another side of the substrate against the ground with a rotation turn 180°. Two BAR64-03 W PIN diodes switches are placed in between a semi-elliptical structure and a rectangular structure on the bottom side of the ground plane. By governing the state of the switches, this antenna can operate at different operating frequencies. Furthermore, the antenna has an accomplished axial ratio (AR) of less than 3 dB for resonating frequencies at all four switching states. Other electromagnetic properties of the proposed jute textile antenna accomplished in simulations were confirmed through the measurement of the antenna in an anechoic chamber. The reconfigurable circularly-polarized jute textile antenna shows a peak gain of 4.93, 5.67, 8.86, and10.07 dBi at 2.4, 3.5, 5.8, and 5.9 GHz (Wi-Fi, Wi-MAX, ISM, W-LAN).

Structural Similarity Measurement Based Cost Function for Stereo Matching of Automotive Applications.

The human visual perception uses structural information to recognize stereo correspondences in natural scenes. Therefore, structural information is important to build an efficient stereo matching algorithm. In this paper, we demonstrate that incorporating the structural information similarity, extracted either from image intensity (SSIM) directly or from image gradients (GSSIM), between two patches can accurately describe the patch structures and, thus, provides more reliable initial cost values. We also address one of the major phenomenons faced in stereo matching for real world scenes, radiometric changes. The performance of the proposed cost functions was evaluated within two stages: the first one considers these costs without aggregation process while the second stage uses the fast adaptive aggregation technique. The experiments were conducted on the real road traffic scenes KITTI 2012 and KITTI 2015 benchmarks. The obtained results demonstrate the potential merits of the proposed stereo similarity measurements under radiometric changes.

Abstract 396: 3d-Engineered Aligned Co-axial Nanofibrous Cardiac Patch for Drug Screening and Cardiac Repair Applications

Introduction: Recent studies have demonstrated the great potential of human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) for testing the efficacy of various cardiac drugs. Additionally, studies have shown that the hiPSC-CMs grown in a 3D environment express better physiological characteristics than 2D cultures. The convergence of polymeric cardiac patch technology with hiPSC-CMs has opened up innovative ways for generating biomimetic 3D cardiac tissues. Hypothesis: The central hypothesis of this study was to develop a 3D cardiac tissue model for pharmacological testing of various cardiac drugs on a 3D nanofibrous aligned co-axial cardiac patch. Methods: A co-axial (Co-A) PCL-gelatin aligned nanofibrous patch was fabricated using the electrospinning technique and its mechanical properties were assessed using Universal Test Machine. Then, the hiPSC-CMs were cultured on this Co-A patch for 2 weeks and the LDH assay was performed to determine the cell viability. The functionality of the cardiac patch was determined by an assessment of calcium cycling in hiPSC-CMs. Further, particle image velocimetry (PIV) and microelectrode array (MEA) was used to evaluate the physiological functionality of the cardiac patch in response to various cardiac drugs. Results: Our studies showed that the mean diameter and thickness of aligned Co-A nanofibrous patch was 578±184 nm and 115±11 μm respectively, while its tensile strength was 0.780 ± 0.098 MPa. Further, confocal imaging confirmed the core-shell structure of the Co-A patches with a core diameter of 2.21 ± 0.50 μm. Additionally, The hiPSC-CMs cultured on these aligned Co-A patches showed an aligned morphology and expressed Troponin-T, GATA4, α-sarcomeric actinin, and connexin-43. The hiPSC-CMs seeded on a 3D scaffold showed efficient calcium cycling properties, which were similar to the hiPSC-CMs cultured in 2D scaffold. Furthermore, PIV and MEA analysis showed that hiPSC-CMs cultured in 2D and 3D showed a similar response to various cardiac drugs, isoproterenol, verapamil and E4031. Conclusions: Overall, this study demonstrated a successful fabrication of aligned Co-A nanofibrous cardiac patch and its evaluation as a 3D cardiac tissue model in-vitro, which could be applied towards drug screening, toxicity studies and cardiac repair applications for ischemic heart disease.

Restoration of the shifting mosaic of floodplain forests under a flow regime altered by a dam

A braided gravel-bed river provides essential habitats for various plants and animals. However, human regulation of rivers, such as dams, channelization, and other engineering works, alter flow and sediment regimes, which generally cause the degradation of river and riparian ecosystems. One of the prominent changes prevailing in Japanese rivers is forest expansion over gravel bars, and many native plants and animals that depend on gravel-bar habitat are now endangered. The Satsunai River is typical of rivers experiencing forest expansion, so the Japanese government launched a restoration project in 2012 to partially restore its riparian ecosystems. This is a large-scale experiment developed jointly by an interdisciplinary science team and river managers, who conduct monitoring and evaluation under an adaptive management scheme. The main measure to restore gravel bed habitat was an artificial flood regime, releasing a maximum water volume of 120 m3/s, which was a 2-year return period flood before dam construction. A unique feature of the project is that we considered the role of high-magnitude floods with recurrence intervals greater than 20 years after dam construction. We hypothesize that the artificial floods can be timed seasonally to create sites for regeneration and nesting of riparian species, and the high-magnitude floods contribute to maintaining a shifting mosaic structure of floodplain forest and unvegetated gravel-bar patches. We also used critical non-dimensional shear stress analysis to define “flood-disturbance areas” that can be disturbed under the artificial flow regime created by a dam. Artificial floods have been initiated once a year since 2012 at the end of June, synchronized with the seed dispersal period of Salix arbutifolia, which is endangered and a high conservation priority in the project. Thus far, the idea of setting floodplain-disturbance areas and the strategy of using both artificial and high-magnitude floods to restore a shifting mosaic of floodplain habitat patches is appropriate, as we found successful regeneration of S. arbutifolia and an exponential decay curve of the age distribution of floodplain forest patches. However, the sediment regime regulated by the dam was not addressed in this research, so future monitoring should track changes in river morphology associated with reduced sediment supply caused by the dam.

Compact Novel Multiband Slotted Microstrip Patch using Grounded Asymmetric Coplanar Strip (GACS) for WLAN and WiMAX Applications

A compacted multiband antenna using grounded asymmetric coplanar strip (GACS) propounded in this paper for multiband applications. The GACS techniques is used to miniaturization of antenna. It has compact size is 19 mm × 19 mm × 1.6 mm3. The suggested antenna has been design on FR4 material with ɛr =4.4 with 1.6 thickness. The monopole antenna is modified by adding L and F strips elements in radiating structure of patch to obtain multiband band resonance. The proposed antenna has application in the bands of WLAN (2.4 GHz-2.5 GHz), Wi-MAX (3.3 GHz-3.6 GHz) and Both WLAN/Wi-MAX (5.5 GHz-5.8 GHz) band. The bandwidth of antenna getting 100MHz, 240MHz and 350MHz at 2.45GHz, 3.55GHz and 5.56GHz. All the three band has VSWR less 1.4.

Stochastic patch structure Nicholson\u2019s blowflies system with mixed delays

This paper is devoted to studying a stochastic patch structure Nicholson’s blowflies system with mixed delays which is a new model for the generalization of classic Nicholson’s blowflies system. We examine stochastically ultimate boundedness and global asymptotic stability for the considered model by stochastic analysis technique. Finally, numerical simulations verify theoretical results of the present paper.

Spectral–Spatial Joint Sparse NMF for Hyperspectral Unmixing

The nonnegative matrix factorization (NMF) combining with spatial–spectral contextual information is an important technique for extracting endmembers and abundances of hyperspectral image (HSI). Most methods constrain unmixing by the local spatial position relationship of pixels or search spectral correlation globally by treating pixels as an independent point in HSI. Unfortunately, they ignore the complex distribution of substance and rich contextual information, which makes them effective in limited cases. In this article, we propose a novel unmixing method via two types of self-similarity to constrain sparse NMF. First, we explore the spatial similarity patch structure of data on the whole image to construct the spatial global self-similarity group between pixels. And according to the regional continuity of the feature distribution, the spectral local self-similarity group of pixels is created inside the superpixel. Then based on the sparse expression of the pixel in the subspace, we sparsely encode the pixels in the same spatial group and spectral group respectively. Finally, the abundance of pixels within each group is forced to be similar to constrain the NMF unmixing framework. Experiments on synthetic and real data fully demonstrate the superiority of our method over other existing methods.

Controlled Drug Release by the Pore Structure in Polydimethylsiloxane Transdermal Patches.

The use of polydimethylsiloxanes (PDMS) as a drug carrier in transdermal adhesive patches is limited and there is insufficient data on the polymer structure and diffusivity, especially when additives modify the matrix. PDMS films with liquid additives (10% w/w): silicone oil (SO), polyoxyethylene glycol (PEG) or propylene glycol (PG) were prepared and indomethacin (IND; 5% w/w) was incorporated as a model active substance. The microstructure of the PDMS matrix and its permeability to water was investigated and correlated to the kinetics of the in-vitro IND release from the film. Three microscopic techniques were used to characterize in detail the microstructure of PDMS films: scanning electron microscopy, fluorescent microscopy and atomic force microscopy. PDMS films with hydrophilic PEG or PG showed different two-phase structures. A two-fold increase in steady-state flux of IND and increased water transport in the presence of PEG was attributed to the pore-like channels created by this polar solvent in the PDMS matrix. This effect was not observed in the films with PG, where only discontinuous droplet-like structures were visible. All additives significantly changed the tensile parameters of the films but the effects were not very pronounced.

STGL: Spatial-Temporal Graph Representation and Learning for Visual Tracking

Tracking-by-detection framework has been normally adopted in visual tracking methods. It aims to localize the visual target object with a bounding box. However, the bounding box is usually difficult to describe the target object accurately and thus easily introduces noisy background information, which usually degrades the final tracking results. Recently, weighted patch representation of the object has been shown very effectively for suppressing the undesirable background information and thus can obviously improve the tracking results. In this paper, we propose a novel Spatial-Temporal Graph representation and Learning (STGL) model to generate a kind of robust target representation for visual tracking problem. The main aspect of STGL is that it aims to exploit both spatial (within each frame) and temporal (between consecutive frames) structure of patches simultaneously in a unified graph representation and semi-supervised learning model. Comparing with existing works, STGL naturally exploits the learned representation of object in previous frame and thus can obtain the representation of object in current frame more accurately and robustly. A new ADMM algorithm is derived to solve the proposed STGL model. Based on the proposed object representation, we then adapt the structured SVM by introducing scale estimation to achieve object tracking. Extensive experiments show that our method outperforms the state-of-the-art patch based tracking methods on two standard benchmark datasets.

Global stability of a multistrain SIS model with superinfection and patch structure

We study the global stability of a multistrain SIS model with superinfection and patch structure. We establish an iterative procedure to obtain a sequence of threshold parameters. By a repeated application of a result by Takeuchi et al. [Nonlinear Anal Real World Appl. 2006;7:235–247], we show that these parameters completely determine the global dynamics of the system: for any number of patches and strains with different infectivities, any subset of the strains can stably coexist depending on the particular choice of the parameters.