bluuebunny/crossref_metadata_2025_split huggingface dataset:
Broadband circularly polarized patch antenna with low crosspolarization using artificial ground structure
Authors: Kai Yujiro , Fukusako Takeshi 
Published: March 2018

AbstractThis letter proposes a circularly polarized patch antenna with 3‐dB AR (axial ratio) and reasonably constant gain characteristics and low crosspolarization covering a wide bandwidth using an AGS (artificial ground structure). The AGS with a rectangular unit cell can expand the 3‐dB axial ratio of CP (circular polarization) and impedance characteristics of circularly polarized patch antennas. For achieving the broadband impedance characteristics, a matching structure is required to keep a sufficient impedance bandwidth between the two parallel resonances separated with a large ratio of frequency. As the matching structure, the outer conductor of a feeding coaxial cable passing through the ground plane is extended to be close to the radiating patch element. However, such matching structure yields large XPOL (crosspolarization) in off‐boresight directions. In this letter, the extended coaxial structure is replaced with a meandering probe for suppressing XPOL and matching impedance. The effect of the meandering probe is discussed with simulated and measured results. As a result, the proposed structure achieves a −10‐dB S11 bandwidth of around 50% and a 3‐dB AR bandwidth of 20%, respectively. The average gain of 7.8 dBic is achieved covering the AR bandwidth. Furthermore, off‐boresight XPOL decreases by around 10 dB compared to the previous structure with the extended coaxial structure in ±30° directions.
Dual notch band UWB antenna with improved notch characteristics
Authors: Sohail Amir , Alimgeer Khurram Saleem , Iftikhar Adnan , Ijaz Bilal , Kim Kang Wook , Mohyuddin Wahab 
Published: March 2018

AbstractIn this article, a novel design of a compact planar Ultra Wideband (UWB) monopole antenna with dual band notched characteristics has been presented. The antenna has a unique structure meeting UWB standards. The proposed antenna is fed through a
micro strip feed line, whereas a better impedance is achieved by truncating the ground plane. The dual notches are achieved by incorporating a meandered slot on the radiator patch and U‐slot in the feed line. The antenna is fabricated on FR‐
substrate having a compact size of
. A good agreement is observed between measured and simulated results. The radiation pattern is omnidirectional in H‐plane, whereas dipole like radiation pattern is observed in the E‐plane. The gain of antenna is stable across the whole UWB except at notched bands. It is shown that any UWB can be notched at any desired frequency band by incorporating appropriate slot length.
A switched‐beam millimeter‐wave array with MIMO configuration for 5G applications
Authors: Ikram Muhammad , Sharawi M. S. , Klionovski K. , Shamim A. 
Published: March 2018

AbstractIn this work, a switched‐beam 2‐element multiple‐input multiple‐output (MIMO) antenna system is proposed at mm‐wave bands for 5G applications. The antenna system consists of a 4 × 4 connected slot antennas for each MIMO element forming the connected antenna array (CAA). A feed network based on a Butler matrix is used to excite the CAA, in addition to steer the beam at different locations which enhance the diversity performances. The mm‐wave MIMO antenna system operates at 28 GHz with at least −10 dB measured bandwidth of 830 MHz (27.4 GHZ–28.23 GHz). It is fabricated on a commercially available RO3003 substrate with dielectric constant of 3.3 and height of 0.13 mm, respectively. The dimensions of the board are equal to 150 mm3 × 100 mm3 × 0.13 mm3. The proposed design is compact, low profile, and suitable for future 5G‐enabled tablet PCs.
A UWB sensor based on resistively‐loaded dipole antenna for skull healing on cranial surgery phantom models
Authors: Lee Doojin , Nowinski Daniel , Augustine Robin 
Published: March 2018

AbstractAfter craniotomy, the monitoring of the skull healing progression is strongly needed to take a proper medical intervention. The CT scans is however currently used for follow‐up after craniotomy resulting in lack of an effective and safety problem. This research proposes an alternative for monitoring the skull healing using ultra‐wide band (UWB) antenna. For the healing of the skull surgical defect, a compact resistively‐loaded dipole antenna is designed and analyzed in terms of its performance in the time domain. The head phantoms having a wideband characteristic are fabricated and used as models for the skull healing process. To represent various mineralization stages, phantoms with various dielectric constants from hydrogel scaffold to the normal skull and their intermediate values are used. The UWB radar technique in the time domain is implemented in the healing process of skull injuries emulating cranial cavities that are made as part of craniosynostosis treatment. The measurement results at the defect area show that the variations in amplitude of the reflected pulse as the skull healing is progressed. The results obtained can contribute to the development of microwave‐based techniques as a preliminary study of a proof concept before clinical trial in the healing process after cranial surgery.
Bandwidth enhancement of Salisbury screen microwave absorber using wire metamaterial
Authors: Bhati Amit , Hiremath Kirankumar R. , Dixit Vivek 
Published: March 2018

AbstractA new design approach that enhances the bandwidth of conventional Salisbury Screen (SS) microwave absorber is investigated. The absorber comprises of, wire metamaterial printed on FR4 substrate, placed on the top of the SS. The SS consists of 50 Ω/sq resistive sheet placed on the metal backed dielectric spacer. The theoretical analysis indicates the bandwidth of SS for −10 dB reflection is 41.1% using FR4 as a spacer for the optimum sheet resistivity of 308 Ω/sq. The proposed absorber shows the bandwidth of 53.5% (8.9–15.4 GHz) for −10 dB reflection. The thickness of the absorber is 0.15 λL (lowest cut‐off frequency for −10 dB reflection). The FR4 substrate with SS works as Jaumann configuration and introduces an additional resonance mode. The selective overlapping of resonant mode excited by wire metamaterial and the additional resonance mode enhances the bandwidth of the absorber. The wire metamaterial is physically realized using low‐cost screen printing technique. The good agreement between the simulated and measured data has been observed.
Millimeter‐wave planar antenna on flexible polyethylene terephthalate substrate with water base silver nanoparticles conductive ink
Authors: Pourahmadazar Javad , Denidni Tayeb A. 
Published: March 2018

AbstractA 60 GHz, mm‐wave array antenna, mounted on a thin flexible polyethylene terephthalate substrate is presented. The proposed 16
8 microstrip series fed array antenna prototype used with laboratory made silver nanoparticles conductive ink used in inkjet technology. The main fabrication problem for this prototype is addressed via ink formulation for printing a homogeneous layer with an excellent electrical conductivity. In comparison to the previous millimeter‐wave series feed structures, the proposed antenna feed network conductive traces 50% is reduced. Silver base conductive ink is prepared in the laboratory with a viscosity of 9–12 cP and a surface tension of 27–32 mN/m for use in Fujifilm DMP‐2831 series. The realized design validate performances of 16‐element linear series sub‐array fed by a three‐stage T‐junction power‐divider network that achieves a 24 dBi gain is presented.
Dielectric resonator antenna array for X‐band and microwave imaging applications
Authors: Gupta Anshul , Reddy Sreeja , Gangwar Ravi Kumar 
Published: March 2018

AbstractIn this article, simulation and experimental studies of compact dielectric resonant antenna array have been performed for microwave imaging systems and X‐band applications. A novel feed structure has been proposed to excite the four cylindrical dielectric resonators. The proposed antenna array shows dual band characteristics i.e., 4.15–7.2 GHz and 9.35–17.2 GHz with the bandwidth of 3.05 GHz and 7.85 GHz respectively. The proposed antenna has been fabricated and tested. Measurement results have been extracted and found in good agreement with simulated results. The proposed antenna array affords appropriate gain, high radiation efficiency, wide bandwidth, small size, and stable radiation patterns over the entire bands which are essential performance characteristics to be utilized for C band, X band, and Ku band applications.
Design of a wide bandwidth and high efficiency circularly polarized microstrip patch antenna using coaxial feeding technique
Authors: Hossain Sheikh Dobir , Rita  , Sobahan K. M. Abdus , Mallick Rony , Hossain F. 
Published: March 2018

AbstractA single band circularly polarized rectangular microstrip patch antenna has been simulated from the cavity equation at first and then the antenna design has been extended to 2 × 2 array. The length and thickness of the each element of the rectangular patch antenna with a slot in the center of the rectangular patch are 38 mm and 0.1 mm, respectively, which are comparatively smaller than our previously presented single‐element circularly polarized microstrip antenna with an I‐slot. In comparison to the bandwidth and efficiency of single element antenna, the quantity have increased about 39% and more than 90%, respectively, in the desired array antenna at the same resonant frequency that is 2.8 GHz. In this article, we also have studied and presented the return loss, bandwidth, gain, directivity, axial ratio of our aimed antenna.
Parametric studies on hexagonal ring based aperture and patch type curved frequency selective surface
Authors: Begam N. , Sarkar S. , Samaddar P. , Saha S. , Chanda (Sarkar) D. , Sarkar P. P. 
Published: March 2018

AbstractSimulated and experimental investigations on hexagonal ring based aperture and patch type semi cylindrical curved frequency selective surfaces (FSSs) have been presented. Simulated and experimental results are in good agreement. Also, the parametric studies have been done for patch and aperture type Curved FSSs. Curved FSS structures are recently being investigated to design radome or nose of fighter aeroplane. This study will help the researchers to design curved frequency selective structures with both band pass and band stop properties.
Compact X‐band bandpass filter using stub‐loaded T‐shape resonator with source‐load coupling
Authors: Zheng Yiyuan , Sheng Weixing 
Published: March 2018

AbstractA novel compact X‐band bandpass filter with a flat and wide passband as well as enhanced out‐of‐band performance is presented based on a source‐load coupling architecture. The proposed architecture is symmetrically constructed of a pair of stepped‐impedance feed structures and an embedded T‐shape resonator, substantially improving the filter's frequency selectivity and passband performance. In order to obtain a broader stopband region, a set of stubs is loaded at the edges of the tapped open stub in the T‐shape resonator. By utilizing a two‐layer low temperature co‐fired ceramic substrate, a prototype filter is implemented and verified experimentally. The filter achieves promising properties of compact size, low‐loss wide passband, high selectivity and good stopband performance simultaneously with an uncomplicated geometry including neither vias nor intricate strips, which exhibits a fairly good potential to be stably used in the highly integrated X‐band microwave systems.
Circularly polarized slot antenna with three‐dimensional ring‐shaped ground plane
Authors: Ko Ting‐Hung , Row Jeen‐Sheen 
Published: March 2018

AbstractA novel design for circularly polarized antennas with broadband operation is proposed. The proposed antenna structure can be regarded as a three‐dimensional version of a planar ring slot antenna, but no printed circuit board is involved in the structure. Moreover, the circular polarization radiation is achieved by introducing a shorting post into the antenna structure as a perturbation element. Measured results indicate that the 3‐dB‐axial‐ratio bandwidth of the proposed antenna is two times larger than that of the printed ring slot antenna with the same aperture size. Simulation results obtained with HFSS also agree well with the experimental data.
A miniaturized UWB monopole antenna with five‐section ground plane slit
Authors: Ul Haq Muhammad Aziz , Koziel Slawomir 
Published: March 2018

AbstractA practical miniaturized ultra‐wideband monopole antenna with a five‐section ground plane slit is proposed. The structure is a modification of a reference antenna designed with the two‐section ground plane slit and featuring the footprint area of 216 mm2. To reduce the antenna size, a ground plane modification was introduced in the form of a five‐section slit below the feeding line. Furthermore, all geometry parameters of the structure were simultaneously optimized. The final design exhibits a small size of only 22.5 × 7.9 mm2 with footprint of 178 mm2 and good electrical and field characteristics. Experimental validation and comparisons with recently reported designs are also provided.
Volumetric segmentation‐free method for rapid visualization of vascular wall shear stress using 4D flow MRI
Authors: Masutani Evan M. , Contijoch Francisco , Kyubwa Espoir , Cheng Joseph , Alley Marcus T. , Vasanawala Shreyas , Hsiao Albert 
Published: March 2018

PurposeTo develop a rapid segmentation‐free method to visualize and compute wall shear stress (WSS) throughout the aorta using 4D Flow MRI data. WSS is the drag force‐per‐area the vessel endothelium exerts on luminal blood; abnormal levels of WSS are associated with cardiovascular pathologies. Previous methods for computing WSS are bottlenecked by labor‐intensive manual segmentation of vessel boundaries. A rapid automated segmentation‐free method for computing WSS is presented.Theory and MethodsShear stress is the dot‐product of the viscous stress tensor and the inward normal vector. The inward normal vectors are approximated as the gradient of fluid speed at every voxel. Subsequently, a 4D map of shear stress is computed as the partial derivatives of velocity with respect to the inward normal vectors. We highlight the shear stress near the wall by fusing visualization with edge‐emphasized anatomical data.ResultsAs a proof‐of‐concept, four cases with aortic pathologies are presented. Visualization allows for rapid localization of pathologic WSS. Subsequent analysis of these pathological regions enables quantification of WSS. Average WSS during peak systole measures approximately 50–60 cPa in nonpathological regions of the aorta and is elevated in regions of stenosis, coarctation, and dissection. WSS is reduced in regions of aneurysm.ConclusionA volumetric technique for calculation and visualization of WSS from 4D Flow MRI data is presented. Traditional labor‐intensive methods for WSS rely on explicit manual segmentation of vessel boundaries before visualization. This automated volumetric strategy for visualization and quantification of WSS may facilitate its clinical translation.
A mixed‐order nonlinear diffusion compressed sensing MR image reconstruction
Authors: Joy Ajin , Paul Joseph Suresh 
Published: March 2018

PurposeAvoid formation of staircase artifacts in nonlinear diffusion‐based MR image reconstruction without compromising computational speed.MethodsWhereas second‐order diffusion encourages the evolution of pixel neighborhood with uniform intensities, fourth‐order diffusion considers smooth region to be not necessarily a uniform intensity region but also a planar region. Therefore, a controlled application of fourth‐order diffusivity function is used to encourage second‐order diffusion to reconstruct the smooth regions of the image as a plane rather than a group of blocks, while not being strong enough to introduce the undesirable speckle effect.ResultsProposed method is compared with second‐ and fourth‐order nonlinear diffusion reconstruction, total variation (TV), total generalized variation, and higher degree TV using in vivo data sets for different undersampling levels with application to dictionary learning‐based reconstruction. It is observed that the proposed technique preserves sharp boundaries in the image while preventing the formation of staircase artifacts in the regions of smoothly varying pixel intensities. It also shows reduced error measures compared with second‐order nonlinear diffusion reconstruction or TV and converges faster than TV‐based methods.ConclusionBecause nonlinear diffusion is known to be an effective alternative to TV for edge‐preserving reconstruction, the crucial aspect of staircase artifact removal is addressed. Reconstruction is found to be stable for the experimentally determined range of fourth‐order regularization parameter, and therefore not does not introduce a parameter search. Hence, the computational simplicity of second‐order diffusion is retained.
The effect of neutralization of nerve growth factor (NGF) on bladder and urethral dysfunction in mice with spinal cord injury
Authors: Wada Naoki , Shimizu Takahiro , Shimizu Nobutaka , de Groat William C. , Kanai Anthony J. , Tyagi Pradeep , Kakizaki Hidehiro , Yoshimura Naoki 
Published: March 2018

AimsTo investigate the role of nerve growth factor (NGF) in lower urinary tract dysfunction in mice with spinal cord injury (SCI).MethodsUsing 4‐week SCI mice, single‐filling cystometry and external urethral sphincter (EUS)‐electromyography were performed under an awake condition. In some SCI mice, anti‐NGF antibodies (10 µg/kg/h) were administered for 1 or 2 weeks before the urodynamic study. NGF levels in the bladder and L6/S1 spinal cord were assayed by ELISA. The transcript levels of P2X receptors and TRP channels in L6/S1 dorsal root ganglia (DRG) were measured by RT‐PCR.ResultsIn SCI mice, the area under the curve of non‐voiding contractions (NVCs) during the storage phase was significantly decreased in both 1‐ and 2‐week anti‐NGF antibody‐treated SCI groups. However, EUS‐electromyogram parameters during voiding were not altered by the treatment. Bladder mucosal and spinal NGF levels were decreased after 2 weeks of anti‐NGF antibody treatment. TRPA1 and TRPV1 transcripts in L6/S1 DRG were significantly decreased after 1‐ or 2‐week anti‐NGF treatment.ConclusionsIn SCI mice, NGF is involved in the emergence of NVCs in association with increased expression of TRP receptors that are predominantly found in C‐fiber afferent pathways. Thus, NGF targeting treatments could be effective for treating storage problems such as detrusor overactivity after SCI.
Optimality principles and decomposition of tracking controllers for weakly dual redundant systems
Authors: Corona Dario , Cristofaro Andrea 
Published: March 2018

SummaryIn this paper, the problem of optimizing the output regulation of a weakly dual redundant plant is addressed. When the system is underactuated, only a subset of the outputs can be arbitrarily controlled and the remaining ones are constrained. With a specific focus on the asymptotic output tracking problem for single‐input systems, we investigate the connection between the overall optimal input and the individually optimal controllers, which leads to the perfect tracking of each output reference. Such relationship is analyzed both for open‐loop and closed‐loop controllers for different cost functions and types of references, and the optimality principles are established, provided that suitable structural conditions are met by the plant matrices.
Controllable self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine)
Authors: Wang Yang , Xu Xinhe , Xu Peng , Feng Xiaobo , Zhang Yanyan , Fu Feiya , Liu Xiangdong 
Published: March 2018

AbstractBlock copolymers can form various ordered structures by self‐assembly, and their composites with inorganic materials may give surprising properties. This review summarizes recent developments in the preparation, mechanism and application of various types of self‐assembly of polystyrene‐block‐poly(2‐vinylpyridine) (PS‐b‐P2VP). The focus of the review is on how to control the self‐assembly of the dynamic and ordered structure of PS‐b‐P2VP based materials by applying effective factors such as thermal annealing, solvent annealing, block composition and blending. Moreover, the combination of the self‐assembly of PS‐b‐P2VP and various nanoparticles, with potentials in drug delivery, sensors and catalysis, is highlighted. © 2018 Society of Chemical Industry
In situ preparation of magnetic Fe3O4.Cu2O.Fe3O4/cryogel nanocomposite powder via a reduction–coprecipitation method as adsorbent for methylene blue water pollutant
Authors: Atta Ayman M , Al‐Lohedan Hamad A , Tawfeek Ahmed M , Ahmed Mona A 
Published: March 2018

AbstractMagnetic nanocomposites have attracted great attention as adsorbents for the removal of water pollutants, which respond to an external magnet that is used to remove both pollutants and composite nanomaterial traces from water. They are environmentally friendly and effective adsorbents for water treatment. In this respect, a simple in situ preparation method was used to prepare cryogel powder composite based on Fe3O4.Cu2O.Fe3O4 nanomaterials. The ionic cryogel based on 2‐acrylamido‐2‐methylpropane sulfonate sodium salt and styrene sulfonate sodium salt was prepared by crosslinking polymerization at low temperature. The new magnetic nanoparticles based on Fe3O4.Cu2O.Fe3O4 were successfully prepared inside the cryogel networks by a simple reduction–coprecipitation method based on reaction of Fe3+ with sodium sulfite and Cu2+ in the presence of hydroxylamine and ammonia solution. The thermal stability, accurate Fe3O4.Cu2O.Fe3O4 content, magnetic properties, crystal lattice structure, particle sizes and morphology of the prepared cryogel composite were evaluated. The optimum conditions such as pH, contact time, adsorbate concentrations, adsorption equilibrium and adsorption kinetics were investigated to determine the efficiency of the prepared composite as an adsorbent to remove toxic methylene blue (MB) pollutant from aqueous solution. The data for MB adsorption confirmed the high ability of the prepared composite to remove more than 4.696 mmol L−1 of MB from water during 6 min. The regeneration and reuse experiments showed excellent data for the synthesized new dye as an effective adsorbent for water treatment. © 2018 Society of Chemical Industry
Academic self‐attributions for success and failure in mathematics and school refusal
Authors: Gonzálvez Carolina , Sanmartín Ricardo , Vicent María , Inglés Cándido J. , Aparicio‐Flores M. Pilar , García‐Fernández José M. 
Published: March 2018

AbstractThe aim of this research is twofold: to analyze the mean differences scores in mathematic self‐attributions based on school refusal and to verify its predictive capability on high scores in school refusal. The Sydney Attribution Scale and the School Refusal Assessment Scale‐Revised were administered to 1078 Spanish students (50.8% boys) aged between 8 and 11 years (M = 9.63; SD = 1.12). School refusers based on negative affect or anxiety attributed their failures more to the lack of capacity and effort, whereas students searching for tangible reinforcements outside of the school were more likely to attribute their successes to capacity. In turn, academic attributions acted as both positive and negative predictors of high‐school refusal. Results are discussed considering more adaptive attributional styles.