bluuebunny/crossref_metadata_2025_split huggingface dataset:
A stable low noise and high gain dual‐band active band‐pass filter with GaAs‐MESFET using CRLH metamaterial
Authors: Yoon Ki‐Cheol , Lee Jong‐Chul 
Published: June 2014

ABSTRACTIn this article, a stable low noise and high gain dual‐band active bandpass filter (BPF) with GaAs‐metal‐semiconductor field effect transistor (MESFET) using composite right‐/left‐handed (CRLH) metamaterial is presented. The CRLH approach in a microstrip structure is applied to develop a dual‐band BPF using an amplifier circuit with two arbitrary frequency bands. The two center frequencies of the filter are then chosen as ω1 = 1.23 GHz and ω2 = 1.63 GHz, where the phase slope characteristics of the response are chosen as −90° and −270° at frequencies of ω1 and ω2, respectively. The experimental results show gain values of 7.82 and 7.03 dB and the return losses of −15.1 and −10.1 dB with bandwidth of 55 (4.4%) and 105 MHz (6.4%) at the center frequencies of 1.22 and 1.61 GHz, respectively. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1985–1988, 2014
A novel protection mechanism for local passive optical networks with bus topology and its verification
Authors: Lafata Pavel 
Published: June 2014

ABSTRACTThe most critical components of passive optical networks (PONs) are usually the central optical line termination unit (OLT) and optical fibers. That is why this article contains the description of a novel protection mechanism for designing of a local PON with a bus topology and enhanced network resilience. The idea is based on using dual OLT units together with contra‐directionally arranged passive splitters to form a bus topology. Thanks to that the resistance of presented PON solution against the potential malfunctions of OLT units as well as optical fibers is significantly increased. Since the application of asymmetric passive splitters is necessary to balance the attenuation and optical signal levels in the entire network, the mathematical model for calculating their optimum splitting ratios is presented as well. Moreover, the functionality of designed bus topology was verified by using real PON equipment and by performing complex measurements. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2005–2010, 2014
Compact dual‐mode differential bandpass filter using stepped impedance resonators
Authors: Shao Chuan , Chen Jian‐Xin , Shi Jin , Bao Zhi‐Hua 
Published: June 2014

ABSTRACTA compact dual‐mode differential bandpass filter using a pair of identical stepped impedance resonators connected by a short microstrip line is presented in this letter. The proposed filter showcases good differential‐mode (DM) bandpass response centered at 2.5 GHz (f0) while possesses inherent bandstop effect across the differential passband for the common‐mode (CM) signal. In addition, there is a transmission zero for the CM operation located within the DM passband. Accordingly, the loaded lumped element or stub for the CM suppression is not required in this design. In addition, compact size and wide stopband of the differential filter are both achieved, and the DM stopband rejection is more than 30 dB up to 8.0 GHz (3.2 f0). © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2055–2058, 2014
An L‐band‐cascaded erbium‐doped fiber amplifier for uniform gain without gain equalizing filter
Authors: Anthony Ricky , Lahiri Rini , Biswas Sambhunath 
Published: June 2014

ABSTRACTIn the letter, a high gain‐naturally flattened L‐band erbium‐doped fiber amplifier (EDFA) is demonstrated. The system uses two bidirectionally pumped lasers for exciting Er3+ in three cascaded fiber amplifiers. The maximum gain of ∼36.4 dB and equalized gain of over 26 dB in the absence of any gain flattening filter with ∼2.5‐dB variation over 35 nm (1572–1608 nm) was obtained. Studies for varying amplifier lengths; signal power and pump powers have also been reported. The proposed EDFA has a noise figure below 5 dB and was found to be stable at extreme temperatures. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2053–2055, 2014
Circular microstrip antenna with dual band‐stop performance for ultrawideband systems
Authors: Ojaroudi Nasser 
Published: June 2014

ABSTRACTIn this article, a novel small monopole antenna with dual band‐notched characteristic for ultrawideband applications is proposed. The proposed antenna consists of circular‐disc radiating patch with a rotated T‐shaped slit, a feed line with a rotated Ω‐shaped split‐ring resonator, and a ground plane. The designed antenna has a small size. The simulated and measured results show that the antenna design exhibits an operating bandwidth (VSWR < 2) from 2.86 to 12.92 GHz with 3.3–4.2 and 5–6 GHz rejected bands covering all the 5.2/5.8 GHz wireless local area network, 3.5/5.5 GHz worldwide interoperability microwave access, and 4 GHz C bands. Good antenna gain and radiation pattern characteristics are obtained in the frequency band of interest. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2095–2098, 2014
A compact balanced antipodal bow‐tie antenna having double notch‐bands
Authors: Dadgarpour Abdolmehdi , Jolani Farid , Yu Yiqiang , Chen Zhizhang , Virdee Bal S. , Denidni Tayeb A. 
Published: June 2014

ABSTRACTA balanced antipodal bow‐tie antenna is presented for ultrawideband (UWB) applications. Bandwidth enhancement and size reduction are achieved by introducing staircase edging to the peripheral of the patch radiator, and by tapering the microstrip feed balun to generate balanced currents on each branch of radiator. The antenna provides band‐notch functionality by embedding dumbbell‐shaped slots within the radiator, and adding an open‐circuit L‐shaped meander stub. The small and low‐profile antenna can easily be fabricated on a single layer of FR4 substrate with dimensions of 26 × 31 × 1.6 mm3. Good correlation is obtained between the simulated and measured results. The antenna operates across 2.8–11 GHz to fully satisfy Federal Communications Commission's UWB specifications. In addition, the antenna provides notch‐bands across 3.3–4 and 5–6 GHz to minimize interference from the WiMAX and WLAN networks. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2010–2014, 2014
Embroidered wearable textile antenna on bending and wet performances for UWB reception
Authors: Shakhirul M. S. , Jusoh M. , Sahadah A. , Nor C. M. , Rahim Hasliza A. 
Published: June 2014

ABSTRACTThis research proposed an integration of the telecommunication system within garment and wearable product known as textile antenna. Such antenna performances on bending and wet conditions are discussed in the manuscript. This embroidered antenna provides a wide operating band satisfying an ultrawideband application of 3.1–10.6 GHz at 10 dB return loss. The proposed antenna is developed from a simple circular with T‐slot structure and a partial ground plane. The fabricated textile antenna was made from both conductive and nonconductive wearable materials. The simulated and measured bend angles of 20°, 30°, 40°, 50°, 60°, 70°, and 80° is analyzed in terms of reflection coefficient via computer simulation technology software and programmable network analyzer, respectively. Moreover, the proposed embroidered antenna performance in wet conditions are investigated in four states of antenna inside water, antenna immediately wet, antenna approximately dry, and antenna completely dry. Simulated and measured results of reflection coefficient, surface current distribution, and gain are presented to validate the usefulness of the presented design. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2158–2163, 2014
Fast solution of low‐frequency complex problems over a frequency band using enhanced A‐EFIE and FMM
Authors: Wu Jun Wei , Qian Zhi Guo , Schutt‐Ainé José E. , Chew Weng Cho 
Published: June 2014

ABSTRACTWe present a fast method for solving low‐frequency complex problems over a frequency band. In this method, we apply fast multipole method to accelerate the solution process of augmented electric field integral equation with perturbation method (enhanced A‐EFIE). As the current is expanded as a power series in frequency in enhanced A‐EFIE, results over a frequency band can be obtained by one low‐cost simulation. Real circuit problem with one million unknowns is used to demonstrate the effectiveness of the method. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2153–2158, 2014
Dual‐band microstrip‐fed bow‐tie antenna for GPS and WLAN application
Authors: Liu Hai‐Wen , Qin Feng , Lei Jiu‐Huai , Wen Pin , Ren Bao‐Ping , Xiao Xiang 
Published: June 2014

ABSTRACTA novel microstrip‐fed bow‐tie antenna for the global positioning system (GPS) and wireless local area network (WLAN) applications is presented in this letter. The proposed antenna consists of two pairs of printed bow‐tie patches with different dimensions, which can generate dual‐band characteristics independently. Based on this design concept, a prototype of the dual‐band antenna is fabricated and measured. The simulated and measured reflection coefficients, together with the radiation patterns, are presented and compared. Measurements show that the 10‐dB impedance bandwidth of the proposed dual‐band bow‐tie antenna is about 670 MHz (1.22–1.89 GHz) and 1130 MHz (5.24–6.37 GHz), which can cover both the GPS and WLAN bands. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2088–2091, 2014
GaN HEMT‐based hybrid current‐mode class‐S power amplifier for 955 MHz LTE signal
Authors: Park Jun‐Chul , Yook Jong‐Gwan , Park Bong Hyuk , Yoo Chan‐Sei , Kim Dongsu , Lee Woo Sung 
Published: June 2014

ABSTRACTThis article presents a gallium nitride‐based hybrid current‐mode class‐S (CMCS) power amplifier (PA) in conjunction with a realized band‐pass delta‐sigma modulator for 955 MHz long‐term evolution (LTE) signal. Commercial surface mount Schottky diodes are located behind switching transistors to protect them against negative voltage swing, and performances are analyzed from the perspective of the variations of the output voltage and current waveforms by the intrinsic components of diode. In particular, the chip‐on‐board technique is adopted to enhance the drain efficiency, and the differential output filter and balun composed of lumped LC resonators are integrated at the back of the switching transistor to extract amplified LTE signal. From the measured results with an 8.5 dB peak to average power ratio 3G LTE 10 MHz input signal, the proposed CMCS PA shows maximum average output power of 37.1 and 32.2 dBm, and the resulting drain efficiencies of 35.5 and 38.5% with the drain voltage of 20 and 10 V, respectively. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2118–2121, 2014
Design of broadband circularly polarized dielectric resonator antenna using improved feed network
Authors: Han Rong‐Cang , Zhong Shun‐Shi , Liu Jing 
Published: June 2014

ABSTRACTThe design of a broadband dual‐feed type circularly polarized rectangular dielectric resonator antenna is presented. Its feed network is of a switched line structure comprised of a 3‐dB Wilkinson power divider and a wideband 90° phase shifter, providing good impedance matching, equal power splitting, and consistent 90° phase shifting over a wide bandwidth. The proposed antenna prototype has been fabricated and measured. The measurements verify that it exhibits advanced characteristics with an impedance bandwidth (VSWR ≤ 2) of 50.8%, an axial ratio bandwidth (AR ≤ 3 dB) of 41.7% and a 3‐dB gain bandwidth of 45.5%. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2191–2195, 2014
Novel 2.4 Ghz branch‐line coupler using microstrip cells
Authors: Salehi Mohamadreza , Noori Leila 
Published: June 2014

ABSTRACTA novel microstrip structure is proposed to design a miniaturized branch‐line coupler operated at 2.4 GHz for Wireless LANs applications. By analyzing different microstrip cells, one method is presented to obtain the perfect input impedance matching condition and another one is proposed to control the resonance frequency. In comparison to the previous works, the proposed coupler features good isolation and negligible phase imbalance equal to 42.9 dB, and 0.09°, respectively. Also in comparison to all of the references in this article, the proposed coupler has a minimum size of 175.1 mm2. Finally, the designed structure is fabricated and measured. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2110–2113, 2014
Meshless implementation of the geometrically exact Kirchhoff–Love shell theory
Authors: Ivannikov V. , Tiago C. , Pimenta P.M. 
Published: June 2014

SUMMARYIn the present paper, a meshless generalized multiple fixed least squares implementation of the geometrically exact Kirchhoff–Love shell theory is described. The material time derivative of the deformation gradient and the first Piola–Kirchhoff stress tensor are considered as basic conjugate quantities to evaluate the internal power. The shell's initial geometry is reproduced exactly by the predefined mapping from a reference plane configuration. As a constitutive model, a neo‐Hookean material, whose functional is altered in compliance with the plane stress condition, is chosen.The augmented weak form, suitable for both interpolative and non‐interpolative approximations thanks to the imposition of the essential boundary conditions through Lagrange multipliers, is consistently linearized, and the resultant bilinear form proved to be symmetric. The appearance of the corner reactions, related to the jumps of the pseudo‐torsion boundary moment, requires the inclusion of additional pointwise displacement constraints at the essential boundary corners. The importance of these quantities is demonstrated in the numerical tests, revealing its positive influence on the displacements and, particularly, their derivatives (up to 3rd order) in both linear and nonlinear problems.The possibility of incorporation of drilling boundary moment for nonlinear problems was successfully assessed. Copyright © 2014 John Wiley & Sons, Ltd.
The geodesic dynamic relaxation method for problems of equilibrium with equality constraint conditions
Authors: Miki Masaaki , Adriaenssens Sigrid , Igarashi Takeo , Kawaguchi Ken'ichi 
Published: June 2014

SUMMARYThis paper presents an extension to the existing dynamic relaxation method to include equality constraint conditions in the process. The existing dynamic relaxation method is presented as a general, gradient‐based, minimization technique. This representation allows for the introduction of the projected gradient, discrete parallel transportation and pull back operators that enable the formulation of the geodesic dynamic relaxation method, a method that accounts for equality constraint conditions. The characteristics of both the existing and geodesic dynamic relaxation methods are discussed in terms of the system's conservation of energy, damping (viscous, kinetic, and drift), and geometry generation. Particular attention is drawn to the introduction of a novel damping approach named drift damping. This technique is essentially a combination of viscous and kinetic damping. It allows for a smooth and fast convergence rate in both the existing and geodesic dynamic relaxation processes. The case study was performed on the form‐finding of an iconic, ridge‐and‐valley, pre‐stressed membrane system, which is supported by masts. The study shows the potential of the proposed method to account for specified (total) length requirements. The geodesic dynamic relaxation technique is widely applicable to the form‐finding of force‐modeled systems (including mechanically and pressurized pre‐stressed membranes) where equality constraint control is desired. Copyright © 2014 John Wiley & Sons, Ltd.
An explicit family of time marching procedures with adaptive dissipation control
Authors: Soares Delfim 
Published: June 2014

SUMMARYIn this work, an explicit family of time marching procedures with adaptive dissipation control is introduced. The proposed technique is conditionally stable, second‐order accurate, and has controllable algorithm dissipation, which adapts according to the properties of the governing system of equations. Thus, spurious modes can be more effectively dissipated and accuracy is improved. Because this is an explicit time integration technique, the new family is quite efficient, requiring no system of equations to be dealt with at each time step. Moreover, the technique is simple and very easy to implement. Numerical results are presented along the paper, illustrating the good performance of the proposed method, as well as its potentialities. Copyright © 2014 John Wiley & Sons, Ltd.
Identification of the Archaeological ‘Invisible Elderly’: An Approach Illustrated with an Anglo‐Saxon Example
Authors: Cave C. , Oxenham M. 
Published: June 2014

AbstractThe aim of this paper is to present a method to facilitate age‐at‐death estimation of older individuals (generally those aged 50+ years) in a representative cemetery sample. The purpose of disaggregating catch‐all categories, such as 50+ years, is to enable the exploration of the elderly (those in their 50s, 60s, 70s or 80s) in the context of mortuary archaeology, bioarchaeology and/or palaeopathology. The methodological steps include the following: (1) assessment of occlusal tooth wear in an Anglo‐Saxon cemetery sample from Worthy Park, UK; (2) seriation of the sample, from youngest to oldest, based on the degree of tooth wear; (3) selection of an ethnographically derived model (known mortality profile) by which seriated individuals in the Worthy Park sample could be reallocated to more realistic or appropriate age classes; (4) reallocation of individuals in the seriated Worthy Park sample to the model age classes. A Hadza, Tanzania, hunter‐gatherer profile was chosen to model the Worthy Park sample, although others are available. By using this model, some 66% of the entire adult sample, originally allocated to the single final age category of 45+ years, was distributed across four new age categories from the mid‐40s to mid‐70s. Relatively straightforward, this approach provides a way to identify those individuals, 50+ years old, not normally sensitive to traditional age‐at‐death estimation methodologies currently available. Copyright © 2014 John Wiley & Sons, Ltd.
Relationships Among Positive Emotions, Coping, Resilience and Mental Health
Authors: Gloria Christian T. , Steinhardt Mary A. 
Published: June 2014

AbstractThe broaden‐and‐build theory of positive emotions suggests that positive emotions can widen the range of potential coping strategies that come to mind and subsequently enhance one's resilience against stress. Studies have shown that high stress, especially chronic levels of stress, strongly contributes to the development of anxiety and depressive symptoms. However, researchers have also found that individuals who possess high levels of resilience are protected from stress and thus report lower levels of anxiety and depressive symptoms. Using a sample of 200 postdoctoral research fellows, the present study examined if (a) positive emotions were associated with greater resilience, (b) coping strategies mediated the link between positive emotions and resilience and (c) resilience moderated the influence of stress on trait anxiety and depressive symptoms. Results support the broaden‐and‐build theory in that positive emotions may enhance resilience directly as well as indirectly through the mediating role of coping strategies—particularly via adaptive coping. Resilience also moderated the association of stress with trait anxiety and depressive symptoms. Although stress is unavoidable and its influences on anxiety and depressive symptoms are undeniable, the likelihood of postdocs developing anxiety or depressive symptoms may be reduced by implementing programmes designed to increase positive emotions, adaptive coping strategies and resilience. Copyright © 2014 John Wiley & Sons, Ltd.
Cytotoxicity of graphene: recent advances and future perspective
Authors: Zhou Ruhong , Gao Huajian 
Published: June 2014

AbstractGraphene, a unique two‐dimensional single‐atom‐thin nanomaterial with exceptional structural, mechanical, and electronic properties, has spurred an enormous interest in many fields, including biomedical applications, which at the same time ignites a growing concern on its biosafety and potential cytotoxicity to human and animal cells. In this review, we present a summary of some very recent studies on this important subject with both experimental and theoretical approaches. The molecular interactions of graphene with proteins, DNAs, and cell membranes (both bacteria and mammalian cells) are discussed in detail. Severe distortions in structures and functions of these biomacromolecules by graphene are identified and characterized. For example, the graphene is shown to disrupt bacteria cell membranes by insertion/cutting as well as destructive extraction of lipid molecules directly. More interestingly, this cytotoxicity has been shown to have implications in de novo design of nanomedicine, such as graphene‐based band‐aid, a potential ‘green’ antibiotics due to its strong physical‐based (instead of chemical‐based) antibacterial capability. These studies have provided a better understanding of graphene nanotoxicity at both cellular and molecular levels, and also suggested therapeutic potential by using graphene's cytotoxicity against bacteria cells.This article is categorized under:

Therapeutic Approaches and Drug Discovery > Nanomedicine for Infectious Disease
Nanotechnology Approaches to Biology > Nanoscale Systems in Biology
Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials
A detailed analysis of methylmalonic acid kinetics during hemodialysis and after combined liver/kidney transplantation in a patient with mut0 methylmalonic acidemia
Authors: Vernon Hilary J. , Sperati C. John , King Joshua D. , Poretti Andrea , Miller Neil R. , Sloan Jennifer L. , Cameron Andrew M. , Myers Donna , Venditti Charles P. , Valle David 
Published: June 2014

AbstractEnd stage kidney disease is a well‐known complication of methylmalonic acidemia (MMA), and can be treated by dialysis, kidney transplant, or combined kidney‐liver transplant. While liver and/or kidney transplantation in MMA may reduce the risk of metabolic crisis and end‐organ disease, it does not fully prevent disease‐related complications. We performed detailed metabolite and kinetic analyses in a 28‐year‐old patient with mut0 MMA who underwent hemodialysis for 6 months prior to receiving a combined liver/kidney transplant. A single hemodialysis session led to a 54 % reduction in plasma methylmalonic acid and yielded a plasma clearance of 103 ml/min and VD0.48 L/kg, which approximates the total body free water space. This was followed by rapid reaccumulation of methylmalonic acid over 24 h to the predialysis concentration in the plasma. Following combined liver/kidney transplantation, the plasma methylmalonic acid was reduced to 3 % of pre‐dialysis levels (6,965 ± 1,638 (SD) μmol/L and 234 ± 100 (SD) μmol/L) but remained >850× higher than the upper limit of normal (0.27 ± 0.08 (SD) μmol/L). Despite substantial post‐operative metabolic improvement, the patient developed significant neurologic complications including acute worsening of vision in the setting of pre‐existing bilateral optic neuropathy, generalized seizures, and a transient, focal leukoencephalopathy. Plasma methylmalonic acid was stable throughout the post‐operative course. The biochemical parameters exhibited by this patient further define the whole body metabolism of methylmalonic acid in the setting of dialysis and subsequent combined liver/kidney transplant.