bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compact low‐pass stepped impedance filters with enhanced out of band response
Authors: El‐halabi Heba , Issa Hamza , Pistono Emmanuel , Kaddour Darine , Abou‐Chahine S. , Ferrari Phillipe 
Published: May 2017

AbstractThis article presents slow‐wave microstrip transmission lines based on a double‐layer PCB substrate for miniaturized and high‐rejection low‐pass filters design. The slow‐wave effect is obtained by inserting metallic via rows within the lower substrate layer. Realized slow‐wave microstrip transmission lines exhibit a high effective dielectric constant of 7.4 instead of 3 for classical microstrip transmission lines. Based on this concept, miniaturized high‐rejection 7th‐order low‐pass stepped‐impedance filters with a cut‐off frequency of 2.45 GHz were designed, fabricated and measured. Measurement results are in good agreement with simulations. Thanks to the slow‐wave microstrip lines, the size of the realized filters is reduced by 65% as compared to a classical filter prototype, without degrading electrical performances.
Compact series FED tapered antenna array using unequal rectangular microstrip antenna elements
Authors: Singh Bharati , Sarwade Nisha , Ray Kamla Prasan 
Published: May 2017

AbstractThis article presents a design of a series fed compact antenna array based on the concept of gain variation of a rectangular microstrip antenna for a desired aperture/amplitude distribution to suppress the first side lobe level (FSLL). An analysis is presented in the X band with respect to the number of elements for series fed antenna arrays. The requirement of a compact design having few numbers of elements with reduced FSLL and beam tilt of 50 degrees has been realized. Simulated results are experimentally validated with reasonable agreement.
A wideband dual‐polarized antenna with L‐shaped resonator
Authors: Wu Rui , Chu Qing‐Xin 
Published: May 2017

AbstractA wideband dual‐polarized antenna loaded resonator is proposed in this article. A new resonant mode is induced while loaded with L‐shaped resonator beside the dipole. This mode can be moved by adjusting the size and position of the resonator. And the main resonant mode is decided by the size of the dipole. In this way, a wide bandwidth of 33.7% from 0.67 to 0.97 GHz for |S11|<−15 dB is achieved with two resonant modes in the desired band. Moreover, stable radiation pattern gain, and low cross polarization are obtained over the entire operating band.
A compact band‐stop frequency selective surface for dual band Wi‐Fi applications
Authors: Ali Haider , Riaz Laeeq , Naeem Umair , Farhan Shafique Muhammad 
Published: May 2017

AbstractThis article presents a compact frequency selective surface (FSS) design which is capable of rejecting both bands of Wi‐Fi. The proposed design is evolved from a patch‐slot topology and it is investigated that the patch‐slot architecture is unstable for oblique incident waves, therefore, a number of geometrical modifications have been proposed to ensure the band stability at different incident angles. The slot geometry is modified by inductive loading and extending the slot length. The modified unit element of FSS is 0.38 λ0 at higher frequency band. Fabricated prototypes have been measured for their transmission response at incident angles upto 30° and good agreement has been observed between simulated and measured results. The proposed FSS is suitable for shielding applications and for limiting the coverage area of wireless access‐point.
Frequency‐agile ring resonator end‐loaded slot antenna
Authors: Szolc L. M. , Poydence T. A. , Ruyle J. E. 
Published: May 2017

AbstractIn this letter, a novel frequency‐agile Ring Resonator End‐Loaded Slot Antenna is proposed, analyzed with a transmission line model, and experimentally verified. The innovative end‐loads are annular slot ring resonators made tunable by way of shunt varactor diode loading. The antenna covers most common mobile communication bands with continuous frequency agility between 1.65 and 2.9 GHz (55% tuning range)—providing realized gains of 2 to 6.6 dB and radiation efficiency on the order of 50% to 90%, respectively. This leads to an improvement of nearly 10 dB in signal‐to‐noise‐ratio in a line‐of‐sight communication link over previously reported frequency agile antennas. The radiation patterns follow the shape of a straight slot radiator on a finite ground plane and vary only slightly when the antenna is tuned to different frequencies.
Design and analysis for dipole antennas with equal beamwidth and wideband operation
Authors: Row Jeen‐Sheen , Wei You‐Heng 
Published: May 2017

AbstractA design for the antenna with equal beamwidths in two orthogonal planes is described. The antenna is mainly composed of a printed dipole fed with a microstrip balun and a rectangular metallic box used as a reflector. The simulated results obtained with HFSS demonstrate that the beamwidths of the antenna in the E‐ and H‐planes as well as the diagonal plane are almost the same within the 10 dB‐return‐loss bandwidth from 2.3 to 3.3 GHz; moreover, the cross polarization in these planes is lower than −20 dB. The spherical vector wave expansion of the radiated fields of the antenna is used to explain the radiation characteristics. An antenna prototype is also constructed, and experimental data have good agreements with the simulation results.
Passive higher order mode filter for 850 nm multimode fiber transmission
Authors: Chorchos L. , Turkiewicz J. P. , Szostkiewicz L. , Napierala M. , Ostrowski L. , Bienkowska B. , Nasilowski T. 
Published: May 2017

AbstractWe propose and evaluate performance of the higher order mode filter for 850 nm multimode fiber transmission. The developed passive component reduces impact of mode dispersion on the systems performance. Excellent operation in the 850 nm transmission experiments is shown.
Octagon fractal microstrip Yagi antenna with a combined DNG and DPS layer structure
Authors: Quzwain K. , Ismail A. , Sali A. 
Published: May 2017

AbstractA high gain octagon fractal microstrip Yagi antenna (OFMYA) at 5.8 GHz industrial, scientific and medical band is presented in this letter. The OFMYA utilizes Cross Snow fractal concept as its director elements. A double‐negative (DNG) and double‐positive (DPS) layers are placed above the OFMYA in order to attain more gain. A prototype of the OFMYA has been etched on Arlon CuClad 217 which has dielectric permittivity of 2.2 and thickness of 0.787 mm. Meanwhile, DNG and DPS are made of Arlon AD1000 having dielectric permittivity of 10.2 and thickness of 0.787. The proposed antenna was simulated and measured. Experimental result shows that the OFMYA with a combined DNG and DPS layer yields a gain of 15.9 dB. It indicates that the proposed antenna in this article is capable to provide a higher gain with a smaller surface size compared to other microstrip Yagi antennas.
Doherty power amplifier with dynamic load modulation for wireless communications
Authors: Kim Gakyoung , Jeong Jinho 
Published: May 2017

AbstractIn this article, Doherty power amplifier (DPA) with dynamic load modulation (DLM) is proposed for wireless communications with high peak‐to‐average ratio (PAR) signals. The proposed DPA with DLM operates as a conventional DPA from peak to 6‐dB back‐off powers, and DLM starts to operate at lower power than 6‐dB back‐off. The DPA with DLM was designed using 6‐W GaN high mobility transistors (HEMTs) at 1.85 GHz. The fabricated DPA with DLM shows a power‐added efficiency (PAE) of 44.7% at 10‐dB back‐off power of continuous‐wave input signal, which is 5% higher than that without DLM. Dynamic measurement was also carried out using 3.84 MHz W‐CDMA signal with 7.4 dB PAR. The measurement of the DPA with DLM exhibits an average PAE of 32.1% at output power of 27.1 dBm, and adjacent channel leakage ratio (ACLR) of −45.1 dBc, which corresponds to 6.1% improvement in PAE compared with the DPA without DLM.
A compact low‐power millimeter wave voltage‐controlled oscillator by using frequency doubling technique
Authors: Hsieh Jian‐Yu , Lu Shey‐Shi 
Published: May 2017

AbstractA V‐band 1‐V compact voltage‐controlled oscillator (VCO) is implemented in 0.18 μm CMOS technology with low power dissipation from 6.3 to 16.1 mW. A proposed frequency doubler can increase oscillation frequency and is also used for replacing varactors and buffers. A 0.1‐mm2 small chip layout area and isolation improvement can be achieved.
Improved side‐coupled three‐line wideband bandpass filter
Authors: Li Li , Lin Haodong , Tian Shu Lin 
Published: May 2017

AbstractThis letter presents an improved side‐coupled three‐line filter, which is loaded by two short‐ended microstrip stubs. The mechanism of improved filter is that the order of original three‐line filter is increased from third order to fifth order. As a result, the fractional reflection bandwidth below −10 dB of improved filter is raised from 75% to 98%, and its selectivity (skirt factor) is enhanced from 64% to 75%. The proposed filter has been fabricated and verified on the substrate of 0.508 mm thickness. It is effective on this thin substrate.
A single feed planar antenna with 4G tunable bands and consistent upper LTE bands between 1.29–2.05 GHz
Authors: Damman Rafid Noel , Mishra Ghanshyam , Sharma Satish K. , Babakhani Behrouz 
Published: May 2017

AbstractA compact single feed dual‐band meandered planar antenna with 4G tunable bands and 1.29–2.05 GHz consistent bands is proposed here. In this antenna design, a varactor diode is implemented on the meandered arm to tune the operational frequency of the lower band between the 690 and 970 MHz frequencies. While the 4G band tuning, the rectangular‐shaped cutout portion of the antenna provides a consistent frequency bandwidth of 1.29–2.05 GHz. The measured fractional bandwidth of the entire tunable lower band range is 33.7% and a consistent 45.5% fractional bandwidth in the higher band. Both the tunable and consistent frequencies are experimentally verified to show acceptable matching based on S11 ≤ −6 dB criteria and near‐omnidirectional radiation patterns. The antenna is able to cover several wireless (LTE) communication bands including 4G.
Dual‐band balanced‐to‐unbalanced out‐of‐phase equal power divider
Authors: Yadav Amar Nath , Bhattacharjee Ratnajit 
Published: May 2017

AbstractThis article proposes a Gysel type dual‐band balanced‐to‐unbalanced (BTU) power divider (PD) for equal power division. The proposed PD has out‐of‐phase (phase difference between two output signal is 180°) characteristic. Standard [S] matrix for the dual‐band PD is derived from mixed mode [S] matrix. Analysis is carried out to obtain design equations of the PD. The proposed PD is designed for a frequency ratio of 1.91. The two design frequencies are 2.2 and 4.2 GHz. A prototype is fabricated to validate theory and design equations. Measurement results show the dual‐band nature and out‐of‐phase characteristic of PD. Size of the fabricated prototype is 0.52λg × 0.29λg. The proposed PD configuration can also be used for high power application.
UWB double‐ridge waveguide coupler with low loss
Authors: Manoochehri Omid , Darvazehban Amin , Erricolo Danilo 
Published: May 2017

AbstractA new ultra‐wide band coupler obtained with two crossed double‐ridge waveguides coupled through one aperture is proposed. The main features of the coupler include operating frequency from 6 to 18 GHz, coupling coefficient below −50 dB, return loss of all the ports under −15 dB, minimum directivity 15 dB, small size, and low losses, which make it appropriate for high‐power applications. The whole structure is simulated with CST and HFSS software, fabricated, and measured. Excellent agreement between measured and simulated results was achieved.
Evaluating the accuracy of theoretical one‐bond 13C─13C scalar couplings and their ability to predict structure in a natural product
Authors: Powell Jacob , Valenti Domenic , Bobnar Harley , Drain Erika , Elliott Blaine , Frank Sydney , McCullough Tyler , Moore Sean , Kettring Andrew , Iuliucci Robbie , Harper James K. 
Published: May 2017

This study explores the feasibility of using a combination of experimental and theoretical 1‐bond 13C─13C scalar couplings (1JCC) to establish structure in organic compounds, including unknowns. Historically, nJCC and nJCH studies have emphasized 2 and 3‐bond couplings, yet 1JCC couplings exhibit significantly larger variations. Moreover, recent improvements in experimental measurement and data processing methods have made 1JCC data more available. Herein, an approach is evaluated in which a collection of theoretical structures is created from a partial nuclear magnetic resonance structural characterization. Computed 1JCC values are compared to experimental data to identify candidates giving the best agreement. This process requires knowledge of the error in theoretical methods, thus the B3LYP, B3PW91, and PBE0 functionals are evaluated by comparing to 27 experimental values from INADEQUATE. Respective errors of ±1.2, ±3.8, and ±2.3 Hz are observed. An initial test of this methodology involves the natural product 5‐methylmellein. In this case, only a single candidate matches experimental data with high statistical confidence. This analysis establishes the intramolecular hydrogen‐bonding arrangement, ring heteroatom identity, and conformation at one position. This approach is then extended to hydroheptelidic acid, a natural product not fully characterized in prior studies. The experimental/theoretical approach proposed herein identifies a single best‐fit structure from among 26 candidates and establishes, for the first time, 1 configuration and 3 conformations to complete the characterization. These results suggest that accurate and complete structural characterizations of many moderately sized organic structures (<800 Da) may be possible using only 1JCC data.
On the long‐range relativistic effects in the 15N NMR chemical shifts of halogenated azines
Authors: Samultsev Dmitry O. , Rusakov Yury Yu. , Krivdin Leonid B. 
Published: May 2017

Long‐range β‐ and γ‐relativistic effects of halogens in 15N NMR chemical shifts of 20 halogenated azines (pyridines, pyrimidines, pyrazines, and 1,3,5‐triazines) are shown to be unessential for fluoro‐, chloro‐, and bromo‐derivatives (1–2 ppm in average). However, for iodocontaining compounds, β‐ and γ‐relativistic effects are important contributors to the accuracy of the 15N calculation. Taking into account long‐range relativistic effects slightly improves the agreement of calculation with experiment. Thus, mean average errors (MAE) of 15N NMR chemical shifts of the title compounds calculated at the non‐relativistic and full 4‐component relativistic levels in gas phase are accordingly 7.8 and 5.5 ppm for the range of about 150 ppm. Taking into account solvent effects within the polarizable continuum model scheme marginally improves agreement of computational results with experiment decreasing MAEs from 7.8 to 7.4 ppm and from 5.5 to 5.3 ppm at the non‐relativistic and relativistic levels, respectively. The best result (MAE: 5.3 ppm) is achieved at the 4‐component relativistic level using Keal and Tozer's KT3 functional used in combination with Dyall's relativistic basis set dyall.av3z with taking into account solvent effects within the polarizable continuum solvation model. The long‐range relativistic effects play a major role (of up to dozen of parts per million) in 15N NMR chemical shifts of halogenated nitrogen‐containing heterocycles, which is especially crucial for iodine derivatives. This effect should apparently be taken into account for practical purposes.
Time‐efficient and flexible design of optimized multishell HARDI diffusion
Authors: Hutter Jana , Tournier J. Donald , Price Anthony N. , Cordero‐Grande Lucilio , Hughes Emer J. , Malik Shaihan , Steinweg Johannes , Bastiani Matteo , Sotiropoulos Stamatios N. , Jbabdi Saad , Andersson Jesper , Edwards A. David , Hajnal Joseph V. 
Published: May 2017

PurposeAdvanced diffusion magnetic resonance imaging benefits from collecting as much data as is feasible but is highly sensitive to subject motion and the risk of data loss increases with longer acquisition times. Our purpose was to create a maximally time‐efficient and flexible diffusion acquisition capability with built‐in robustness to partially acquired or interrupted scans. Our framework has been developed for the developing Human Connectome Project, but different application domains are equally possible.MethodsComplete flexibility in the sampling of diffusion space combined with free choice of phase‐encode‐direction and the temporal ordering of the sampling scheme was developed taking into account motion robustness, internal consistency, and hardware limits. A split‐diffusion‐gradient preparation, multiband acceleration, and a restart capacity were added.ResultsThe framework was used to explore different parameters choices for the desired high angular resolution diffusion imaging diffusion sampling. For the developing Human Connectome Project, a high‐angular resolution, maximally time‐efficient (20 min) multishell protocol with 300 diffusion‐weighted volumes was acquired in >400 neonates. An optimal design of a high‐resolution (1.2 × 1.2 mm2) two‐shell acquisition with 54 diffusion weighted volumes was obtained using a split‐gradient design.ConclusionThe presented framework provides flexibility to generate time‐efficient and motion‐robust diffusion magnetic resonance imaging acquisitions taking into account hardware constraints that might otherwise result in sub‐optimal choices. Magn Reson Med 79:1276–1292, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
On boundary conditions for homogenization of volume elements undergoing localization
Authors: Goldmann Joseph , Brummund Jörg , Ulbricht Volker 
Published: May 2017

SummaryThis paper presents an adaption of periodic boundary conditions (BC), which is termed tessellation BC. While periodic BC restrict strain localization zones to obey the periodicity of the microstructure, the proposed tessellation BC adjust the periodicity frame to meet the localization zone. Thereby, arbitrary developing localization zones are permitted. Still the formulation is intrinsically unsusceptible against spurious localization. Additionally, a modification of the Hough transformation is derived, which constitutes an unbiased criterion for the detection of the localization zone. The behavior of the derived formulation is demonstrated by various examples and compared with other BC. It is thereby shown that tessellation BC lead to a reasonable dependence of the effective stress on the localization direction. Furthermore, good convergence of stiffness values with increasing size of the representative volume element is shown as well as beneficial characteristics in use with strain softening material.
Joint association of birth weight and physical activity/sedentary behavior with obesity in children ages 9‐11 years from 12 countries
Authors: Qiao Yijuan , Zhang Tao , Liu Hongyan , Katzmarzyk Peter T. , Chaput Jean‐Philippe , Fogelholm Mikael , Johnson William D. , Kuriyan Rebecca , Kurpad Anura , Lambert Estelle V. , Maher Carol , Maia José A.R. , Matsudo Victor , Olds Timothy , Onywera Vincent , Sarmiento Olga L. , Standage Martyn , Tremblay Mark S. , Tudor‐Locke Catrine , Zhao Pei , Hu Gang ,   for the ISCOLE Research Group
Published: May 2017

ObjectiveTo examine the joint association of birth weight and physical activity/sedentary time with childhood obesity in 12 countries.MethodsA cross‐sectional study of 5,088 children aged 9 to 11 years was conducted. Birth weight was recalled by parents or guardians. Moderate‐to‐vigorous physical activity (MVPA) and sedentary behavior were objectively measured using accelerometry.ResultsThe association of birth weight with the odds of obesity, central obesity, and high body fat was significant among children with either low MVPA or high sedentary time but not among children with either high MVPA or low sedentary time. In comparison with children with normal birth weight and high MVPA, children with high birth weight and low MVPA showed 4.48‐ to 5.18‐fold higher odds of obesity, central obesity, and high body fat; children with normal birth weight and low MVPA showed 3.00‐ to 3.30‐fold higher odds of obesity, central obesity, and high body fat, and children with high birth weight and high MVPA showed 1.16‐ to 1.68‐fold higher odds of obesity, central obesity, and high body fat.ConclusionsHigh MVPA is more important than high birth weight as a correlate of obesity in children.
The influence of soft segments on some properties of new transparent segmented polyurethanes
Authors: Puszka Andrzej , Kultys Anna 
Published: May 2017

This work describes the synthesis and structure of the new segmented polyurethanes (SPURs) formed from an aliphatic diisocyanate [1,1′‐methanediylbis(4‐isocyanatocyclohexane] (Desmodur W®) and unconventional sulfur‐containing chain extender [2,2′‐methylenebis([4,1‐phenylene]methylenesulfanediyl)diethanol]. Soft segments were poly(oxytetramethylene)diol of
= 1000 g/mol (PTMO) or poly(hexametylene carbonate)diol of
= 860 g/mol (PHCD). For all the polymers, the structure, physicochemical, thermal, and mechanical properties were determined. In addition, for selected polymers, optical properties (refractive index and transparency), adhesive properties, and antimicrobial activity were also determined. The type and amount of soft segment used for the synthesis of SPURs had a significant effect on the properties of the polymers. SPURs from PHCD are characterized by higher glass transition temperatures, molar masses, hardness (up to 91/50°Sh in scale A/D), and tensile strengths (up to 36.5 MPa) but lower elongations at break compared with the SPURs with PTMO. The tests of adhesion and optical properties showed that the PHCD‐based SPUR was characterized by higher value of refractive index, transparency, and more than three times the adhesive strength than the PTMO‐based SPUR. Antimicrobial activity studies showed that the SPUR presence in the medium inhibited proliferation of both Gram‐positive and Gram‐negative bacteria. Copyright © 2017 John Wiley & Sons, Ltd.