bluuebunny/crossref_metadata_2025 huggingface dataset:
Uma abordagem estrutural em redes: expondo padrões, possibilidades e armadilhas
Authors: Alves Carlos Alberto , Santos Suzana Bierrenbach de Souza
Published: September 2011

Atualmente, nota-se uma mudança nos paradigmas de avaliação que se deslocam de explicações atomísticas, positivistas e individualistas dos fenômenos para aqueles que procuram um entendimento mais relacional, contextual e sistêmico. Esse interesse crescente nos inter-relacionamentos, ou redes de conexões entre entidades, torna-se aparente em campos como estudos de organizações em redes, disseminação de conhecimentos, grupos sociais, entre outros. Uma base teórica crescente e metodológica está fornecendo melhores capacidades para descobrir as atuais topologias ou padrões de conexões entre entidades, elementos, pessoas, organizações ou comunidades, possibilitando uma análise mais fina dos seus elementos. Desse modo, a análise de redes difere das avaliações convencionais e modos de pesquisas, já que seu foco está nos inter-relacionamentos entre atores e instituições e não nas suas características individuais. Neste artigo, o objetivo geral é revisar e analisar a capacidade emergente do paradigma de redes como um método investigativo, bem como demonstrar como tal modelo pode ser aplicado em uma grande variedade de áreas. Fazendo isso, será esboçada uma proposta de estrutura guia para investigação em redes que estabelece alguns indicadoreschave, destaca aspectos metodológicos e, também, algumas possíveis falhas.
Reestruturação organizacional e reconstrução da identidade: um estudo de caso em uma empresa de telecomunicações
Authors: Soares Daniela Cristina , Vieira Adriane
Published: September 2011

Esta pesquisa teve como objetivo principal analisar o impacto da reestruturação organizacional ocorrida em uma empresa de telefonia celular na identidade dos funcionários. O tema diz respeito às profundas transformações que vêm ocorrendo no mundo do trabalho, derivadas da conjugação entre globalização da economia, inovações tecnológicas e novas formas de gestão. A metodologia adotada é de natureza qualitativa-descritiva e os dados foram coletados por meio de 22 entrevistas semiestruturadas. No plano teórico foram abordados dois temas fundamentais que são as mudanças contemporâneas nas relações de trabalho e seus reflexos sobre a identidade dos trabalhadores. Os resultados da pesquisa mostram que o processo de reestruturação organizacional culminou com a demissão simultânea de 382 funcionários da área de call center e foi conduzido de forma cruel e impiedosa. Os gestores foram informados da decisão da empresa dois dias antes do ocorrido e a atuação da área de Recursos Humanos limitou-se ao atendimento dos aspectos burocráticos. A experiência vivida pelos entrevistados gerou sentimentos de surpresa, decepção, tristeza e angústia, afetando negativamente o processo de construção e reconstrução das identidades.
The isotopic composition of precipitation from a winter storm – a case study with the limited-area model COSMOiso
Authors: Pfahl S. , Wernli H. , Yoshimura K.
Published: September 2011

Abstract. Stable water isotopes are valuable tracers of the atmospheric water cycle, and potentially provide useful information also on weather-related processes. In order to further explore this potential, the water isotopes H218O and HDO are incorporated into the limited-area model COSMO. In a first case study, the new COSMOiso model is used for simulating a winter storm event in January 1986 over the eastern United States associated with intense frontal precipitation. The modelled isotope ratios in precipitation and water vapour are compared to spatially distributed δ18O observations. COSMOiso very accurately reproduces the statistical distribution of δ18O in precipitation, and also the synoptic-scale spatial pattern and temporal evolution agree well with the measurements. Perpendicular to the front that triggers most of the rainfall during the event, the model simulates a gradient in the isotopic composition of the precipitation, with high δ18O values in the warm air and lower values in the cold sector behind the front. This spatial pattern is created through an interplay of large scale air mass advection, removal of heavy isotopes by precipitation at the front and microphysical interactions between rain drops and water vapour beneath the cloud base. This investigation illustrates the usefulness of high resolution, event-based model simulations for understanding the complex processes that cause synoptic-scale variability of the isotopic composition of atmospheric waters. In future research, this will be particularly beneficial in combination with laser spectrometric isotope observations with high temporal resolution.
WRF-CMAQ two-way coupled system with aerosol feedback: software development and preliminary results
Authors: Wong D. C. , Pleim J. , Mathur R. , Binkowski F. , Otte T. , Gilliam R. , Pouliot G. , Xiu A. , Young J. O. , Kang D.
Published: September 2011

Abstract. Air quality models such as the EPA Community Multiscale Air Quality (CMAQ) require meteorological data as part of the input to drive the chemistry and transport simulation. The Meteorology-Chemistry Interface Processor (MCIP) is used to convert meteorological data into CMAQ-ready input. Key shortcoming of such one-way coupling include: excessive temporal interpolation of coarsely saved meteorological input and lack of feedback of atmospheric pollutant loading on simulated dynamics. We have developed a two-way coupled system to address these issues. A single source code principle was used to construct this two-way coupling system so that CMAQ can be consistently executed as a stand-alone model or part of the coupled system without any code changes; this approach eliminates maintenance of separate code versions for the coupled and uncoupled systems. The design also provides the flexibility to permit users: (1) to adjust the call frequency of WRF and CMAQ to balance the accuracy of the simulation versus computational intensity of the system, and (2) to execute the two-way coupling system with feedbacks to study the effect of gases and aerosols on short wave radiation and subsequent simulated dynamics. Details on the development and implementation of this two-way coupled system are provided. When the coupled system is executed without radiative feedback, computational time is virtually identical when using the Community Atmospheric Model (CAM) radiation option and a slightly increased (~8.5 %) when using the Rapid Radiative Transfer Model for GCMs (RRTMG) radiation option in the coupled system compared to the offline WRF-CMAQ system. Once the feedback mechanism is turned on, the execution time increases only slightly with CAM but increases about 60 % with RRTMG due to the use of a more detailed Mie calculation in this implementation of feedback mechanism. This two-way model with radiative feedback shows noticeably reduced bias in simulated surface shortwave radiation and 2 m temperatures as well improved correlation of simulated ambient ozone and PM2.5 relative to observed values for a test case with significant tropospheric aerosol loading from California wildfires.
The influence of land cover roughness on the results of high resolution tsunami inundation modeling
Authors: Kaiser G. , Scheele L. , Kortenhaus A. , Løvholt F. , Römer H. , Leschka S.
Published: September 2011

Abstract. In this paper a local case study is presented in which detailed inundation simulations have been performed to support damage analysis and risk assessment related to the 2004 tsunami in Phang Nga and Phuket, Thailand. Besides tsunami sources, bathymetry and topography, bottom roughness induced by vegetation and built environment is considered to influence inundation characteristics, such as water depths or flow velocities and therefore attracts major attention in this work. Plenty of information available on the 2004 tsunami event, high-resolution satellite imagery and extensive field measurements to derive land cover information and forest stand parameters facilitated the generation of topographic datasets, land cover maps and site-specific Manning values for the most prominent land cover classes in the study areas. The numerical models ComMIT and Mike 21 FM were used to hindcast the observed tsunami inundation and to draw conclusions on the influence of land cover on inundation patterns. Results show a strong influence of dense vegetation on flow velocities, which were reduced by up to 50% by mangroves, while the inundation extent is influenced only to a lesser extent. In urban areas, the disregard of buildings in the model led to a significant overestimation of the inundation extent. Hence different approaches to consider buildings were used and analyzed in the model. The case study highlights the importance and quantifies the effects of considering land cover roughness in inundation simulations used for local risk assessment.
Segurança do cliente e as ações frente ao procedimento cirúrgico
Authors: Grigoleto Andréia Regina Lopes , Gimenes Fernanda Raphael Escobar , Avelar Maria Do Carmo Querido
Published: September 2011

O procedimento anestésico-cirúrgico é parte integrante da assistência à saúde, contribuindo na prevenção de agravos à integridade física e perda de vidas. Como estratégia na redução desses eventos a Organização Mundial da Saúde lançou a campanha “cirurgias seguras salvam vidas”. Com o objetivo de discutir as ações voltadas à segurança dos pacientes no período operatório, buscou-se no site da Organização Mundial da Saúde os estudos disponíveis sobre avanços na execução de procedimentos seguros, com a implementação do Checklist, na sistematização dos cuidados preconizados no centro cirúrgico, que garantam alta eficácia e baixo custo. O estudo explicita e discorre sobre a estratégia de utilização do Sistema “Checklist”, apresentando ações específicas que permeiam três momentos do procedimento anestésico-cirúrgico. A implementação do Checklist confere o alcance do procedimento correto, pela equipe correta e paciente correto, tendo em vista estabelecer processos seguros na realização da cirurgia. Descritores: Enfermagem; Cirurgia; Gerenciamento de Segurança; Organização Mundial da Saúde.
Atendimento pelo SUS na percepção de mulheres com lesões de câncer cervicouterino em Goiânia-GO
Authors: Albuquerque Zair Benedita Pinheiro de , Tavares Suelene Brito do Nascimento , Manrique Edna Joana Claudio , Souza Adenícia Custodio Silva e , Neves Heliny Carneiro Cunha , Valadares Janaina Guimarães , Amaral Rita Goreti
Published: September 2011

O câncer de colo do útero é prioridade nas políticas de saúde no Brasil. Apesar da existência do fluxo de atendimento estabelecido pelo Sistema Único de Saúde (SUS), fragilidades são observadas na sua operacionalização. Objetivou-se analisar a percepção de mulheres com lesões de colo do útero acerca do atendimento pelo SUS em Goiânia-GO. Estudo descritivo, exploratório de abordagem qualitativa. Os dados foram obtidos por meio de entrevistas, utilizando-se a técnica de incidente crítico e análise de conteúdo. Na percepção das mulheres, o atendimento é permeado por falhas no acolhimento, comunicação, assistência do profissional de saúde, falta de efetividade e pelo desconhecimento do próprio fluxo de atendimento. Evidenciou-se a necessidade de reorientação do atual modelo assistencial de atendimento, com abordagens conscientizadoras, que permitam aos profissionais e aos gestores desenvolverem habilidades de ouvir, acolher e de se responsabilizar pelo cuidado, a fim de promover a transformação dessa realidade.Descritores: Neoplasias do colo do útero; Saúde Pública; Percepção; Saúde da Mulher.
Contribuições do estágio extracurricular para as competências profissionais: percepções de enfermeiros de um hospital público
Authors: Paiva Kely Cesar Martins de , Martins Vera Lúcia Vieira
Published: September 2011

Este estudo teve como objetivo descrever e analisar como os enfermeiros de um hospital público de Belo Horizonte (MG) percebem as contribuições ideais (desejada) e reais (efetiva), do estágio extracurricular para o processo de formação e desenvolvimento de competências profissionais dos acadêmicos de Enfermagem, dada sua importância na formação acadêmica e profissional do estudante durante tal processo pedagógico. Na pesquisa de campo, descritiva e com abordagem quantitativa, os dados foram coletados por meio de um questionário aplicado a 65 enfermeiros que acompanham os acadêmicos durante o estágio extracurricular. Os resultados mostraram que, tanto do ponto de vista do ideal como do real, tal modalidade de estágio tem contribuído para a formação dos acadêmicos. No entanto, alguns pontos de defasagem foram identificados, os quais carecem de atenção por parte de todos os atores envolvidos: Estado, instituições de ensino, o hospital, os acadêmicos e os enfermeiros que os acompanham.Descritores: Enfermagem; Educação em enfermagem; Educação baseada em competências; Competência profissional.
Second Law Analysis of Mixed Convection in a Laminar, Non-Newtonian Fluid Flow through a Vertical Channel
Authors: Gorla Rama Subba Reddy
Published: September 2011

The fully developed mixed convection of non-Newtonian laminar flow through a vertical channel is investigated. The boundary conditions of uniform and unequal temperature prescribed at the channel walls are considered. The velocity and temperature fields are obtained by analytically solving the momentum and energy balance equations. The velocity and temperature distributions are used to calculate the entropy generation number (), the irreversibility ratio (Φ), and the Bejan number (Be) for several values of the viscous dissipation parameter (), the viscosity index (), and the appropriate dimensionless coordinates. The results show us the regions of high entropy generation.
The Odd–Even Effect in Sudoku Puzzles: Effects of Working Memory, Aging, and Experience
Authors: Chang Hye-Sang , Gibson Janet M.
Published: September 2011

The odd–even effect in numerical processing has been explained as the easier processing of even numbers compared with odd numbers. We investigated this effect in Sudoku puzzles, a reasoning problem that uses numbers but does not require arithmetic operations. Specifically, we asked whether the odd–even effect occurred with Sudoku puzzles and whether individual differences in working memory (WM), aging, and experience with Sudoku modulated this effect. We manipulated the presence of odd and even numbers in Sudoku puzzles, measured WM with the Wisconsin Card Sorting Test and backward digit span task, tested older and younger adults, and collected Sudoku experience frequency. Performance on Sudoku was more accurate for even puzzles than odd ones. Younger, experienced, and higher-WM participants were more accurate on Sudoku, but these individual difference variables did not interact with the odd–even effect. Odd numbers may impose more cognitive load than even numbers, but future research is needed to examine how age, experience, or WM may influence the odd–even effect.
Cell death‐inducing DFF45‐like effector b (Cideb) is present in pancreatic beta‐cells and involved in palmitate induced beta‐cell apoptosis
Authors: Li H. , Song Y. , Zhang L. J. , Li F. F. , Gu Y. , Zhang J. , Dong W. P. , Xue L. , Zhang L. Y. , Liu F. , Wang J. , Jiang L. N. , Ye J. , Li Q.
Published: September 2011

Background

Excessive accumulation of long‐chain fatty acids in the pancreatic islets is associated with beta cell dysfunction and ultimately contributes to the pathogenesis of type 2 diabetes. It has been well proved that the cell death‐inducing DFF45‐like effector b (Cideb) is involved in cell apoptosis and lipid metabolism. However, the expression and function of Cideb in endocrine pancreas remain to be investigated.

Methods

By using reverse transcript polymerase chain reaction, immunohistochemistry and Western blot, we observed the expression of Cideb in pancreas tissues and clonal beta‐cell lines. The physiological role of Cideb was examined under the free fatty acid (FFA) administration and Cideb ribonucleic acid interference, and further analysis on apoptosis was measured by terminal deoxynucleotidyl transferase‐mediated deoxyuridine triphosphate nick end labelling assay and caspase‐3 activity. Nile red staining and quantitative evaluation of triglyceride were used to detect the lipid accumulation. The changes in esterification of FFA were traced by radiolabelled palmitate.

Results

Cideb was abundantly expressed in pancreas and mainly localized in beta cells. FFAs, especially palmitate, induced an obvious increase of Cideb expression in beta cell lines. Adenoviral‐mediated overexpression of Cideb increased the apoptosis, whereas ribonucleic acid interference‐based Cideb depletion in beta‐TC3 cells had no effect on apoptosis in normal condition. Palmitate supplementation led to beta cell lipoapoptosis, and Cideb silencing exacerbated the apoptosis induced by palmitate, reduced intracellular triglyceride content and aggravated FFA overload in beta cells.

Conclusions

The present results suggest that increased Cideb expression upon palmitate exposure may be involved in beta cell lipoapoptosis through its influence on conversion of FFAs to lipid esters in lipid droplets. Copyright © 2011 John Wiley & Sons, Ltd.
Laser microstructuring of photomodified fluorinated ethylene propylene surface for confined growth of Chinese hamster ovary cells and single cell isolation
Authors: Yakunin S. , Fahrner M. , Reisinger B. , Itani H. , Romanin C. , Heitz J.
Published: September 2011

We present a method for laser lithography of cell‐adhesive arrays on a fluoropolymer surface. The method is based on 172 nm excimer‐lamp photomodification in ammonia atmosphere followed by microstructuring by laser ablation. The improved wettability of the polymer is caused by new chemical groups on the surface after the UV treatment that we proved by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy analyses. The cell adhesion properties of micropatterned structures were tested by cultivation of mammalian cells. We show that single elongated cells can grow confined to lines with sharply defined boundaries of the cell‐covered areas. In preliminary experiments, we also demonstrate that the described technique allows the production of single‐cell arrays with variable cell shape. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Quasihybrid scheme of nonuniform rational B‐spline–uniform geometrical theory of diffraction method for radiation of antennas
Authors: Wang Nan , Dang Xiaojie , Yuan Haobo , Liang Changhong
Published: September 2011

The nonuniform rational B‐spline–uniform geometrical theory of diffraction (NURBS‐UTD) method is studied in this paper. To deal with arbitrary wire antennas without analytical directional functions, a quasihybrid scheme is presented to discuss the radiation pattern of wire antennas mounted around electrically large targets. The NURBS technique is introduced to construct targets, the wire antennas, and electrically large targets are analyzed by method of moment (MoM) and NURBS‐UTD, respectively. Information from results of ray tracing is chosen as interface between MoM and NURBS‐UTD to form quasihybrid scheme. The practicability and validity can be seen from examples given. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2963–2967, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26374
A simple and an accurate method for measuring the phase‐frequency response of fiber fabry‐perot tunable filter
Authors: Qi Haibing , Wei Shuhua , Yu Yonglin
Published: September 2011

A simple and an accurate method for measuring the phase‐frequency response of fiber Fabry‐Perot (FFP) tunable filter driven by piezoelectric (PZT) is proposed and demonstrated.Considering the phase shift factor θ(f) induced by PZT in the transfer function of the filter, the derived equation shows a method to perform the phase‐frequency response of the filter by measuring the time delay between the maximum point of the input electrical signal and the local minimum point of the optical output signal. In this article the measured phase differences of a FFP tunable filter range from −0.4 to −220° with frequency from 40 Hz to 30 kHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2960–2963, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26375
Ultra‐wideband bandpass filters with a controllable and highly selective notch‐band
Authors: Zhou Liang , Liu Shao‐bin , Kong Xiang‐kun , Zhang Hai‐feng , Guo Ya‐nan
Published: September 2011

In this letter, a novel band‐notched ultra‐wideband (UWB) bandpass filter (BPF) is investigated. A structure of complementary two turns spiral resonator (CSR2) is proposed to improve notch performance of the UWB BPF. The single CSR2 unit cell has a size of 0.08λg × 0.08λg(what is λg) at stop‐band center frequency (5.7 GHz). With respect to the resonance nature of the miniaturization and high Q value, a compact UWB BPF with multiple CSR2s is designed. The proposed filter demonstrates band‐stop‐filter‐like response with high frequency selectivity and controllable bandwidth at rejection band. We assess the filtering behavior of structures from two aspects: the return loss and the group delay. The measured notched band frequency is range from 5.05 to 5.85 GHz(|S11|<−10dB). The maximum attenuation is more than 28 dB at the central frequency of 5.37 GHz. The measured and simulated results are well‐complied with each other. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2920–2922, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26376
Wwan/lte printed loop tablet computer antenna and its body sar analysis
Authors: Wong Kin‐Lu , Wei Wan‐Jhu , Chou Liang‐Che
Published: September 2011

A WWAN/LTE printed loop antenna for tablet computer application is presented.The printed loop antenna is a half‐wavelength loop strip coupled‐fed by a patch monopole, which performs not only as a coupling feed but also as an efficient radiator for the antenna. By embedding a printed distributed inductor in the loop strip, dual‐resonance excitation of the half‐wavelength mode of the coupled‐fed loop antenna is obtained, which forms the antenna's lower band at about 800 MHz to cover the LTE700/GSM850/900 operation (704–960 MHz). The antenna's upper band is formed by both the resonant modes contributed by the patch monopole and the higher order resonant modes contributed by the loop strip. The upper band shows a large bandwidth (>1 GHz) to cover the GSM1800/1900/UMTS/LTE2300/2500 operation (1710–2690 MHz). Further, with a planar and compact structure (12 × 75 mm2), the antenna is suitable to be disposed in the limited space inside the tablet computer and meets the body specific absorption rate (SAR) requirement (<1.6 W/kg for 1‐g body tissue) for practical applications. Details of the proposed antenna and its body SAR results are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2912–2919, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26377
Investigation of an ultra‐wideband microstrip antenna using finite elementary lines approach
Authors: Senouci S. , Zerguerras A. , Tao J. , Vuong T. H.
Published: September 2011

This work presents an investigation, using the approach of finite elementary lines (FEL), of an ultra‐wideband antenna. Two ways for expanding frequency band were combined: the electromagnetic coupling and the insertion of an air layer. A prototype of this antenna has been realized. A comparison between the antenna performance predicted by our approach and those provided by the high‐frequency simulation structure (HFSS) software and those measured is presented. An impedance bandwidth of about 50% and directivity at the first resonance of about 9 dB were achieved. A satisfactory concordance between results of our approach and measures is observed. The novelty of this work lies in the treatment by the FEL method, for the first time, of singularities induced by the gap of coupling and the jump of width. The computing time consumed by the FEL approach is about 10 times less than that consumed by the HFSS software to analyze the same structure on the same number of point's frequency domain, the latter being 68 min. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2978–2985, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26379
A 3.4/5.5 GHz dual‐band notched UWB printed monopole antenna with two open‐circuited stubs in the microstrip feedline
Authors: Panda Jyoti Ranjan , Kshetrimayum Rakhesh Singh
Published: September 2011

An ultrawideband (UWB) printed monopole antenna (PMA) for the 3.4/5.5 GHz dual‐band notched operation is presented.The antenna has a rectangular radiating element with a symmetrical staircase structure in the bottom or feed region and fed by a 50‐Ω microstrip line. By introducing two open‐circuited stubs from the two sides of the microstrip feedline, dual band‐notched characteristics in the WiMAX/WLAN bands are achieved. The proposed antenna is effectively designed, simulated, fabricated, and measured providing broadband impedance matching, appropriate gain, and stable radiation pattern characteristics. An UWB and single band‐notched UWB antenna are also fabricated for comparison. The proposed UWB antenna is investigated in time domain, and it has been observed experimentally that the received fifth derivative of Gaussian pulse is not distorted in the main waveform but some amount of ringing is observed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2973–2978, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26380
Substrate integrated waveguide filter design with wave concept iterative procedure
Authors: Alhzzoury A. Ismail , Raveu N. , Prigent G. , Pigaglio O. , Baudrand H. , Al‐Abdullah K.
Published: September 2011

A bandpass filter in substrate integrated waveguide (SIW) technology is designed with its suitable excitation. Sensitivity analysis of the SIW filter electrical response toward the number and positions of metallic via holes are performed using wave concept iterative procedure. It leads to a reduction of the number of vias with identical performance of the filter. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2939–2942, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26381
Enhancement of the rejection bandwidth of microwave‐coupled lines filters using spurline structures
Authors: Loo‐Yau J. R. , Gómez‐Pichardo O. I. , Sandoval‐Ibarra F. , Maya‐Sánchez M. C. , Reynoso‐Hernández J. A.
Published: September 2011

A new bandstop‐coupled line filter using spurline structures has been presented in this work. The new bandstop filter enhances the rejection bandwidth of bandstop coupled line filters in a 50%. To demonstrate the idea, classical bandstop‐coupled line filters with and without simple spurlines structure were designed using Rogers material, and their frequency response were compared. Simulations performed with momentum agree with experimental results, demonstrating the usefulness of spurlines structures in the enhancement of the bandwidth of coupled line filters. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2893–2896, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26382
A Q‐band CMOS low‐noise amplifier using a low‐voltage cascode in 0.13‐μm CMOS technology
Authors: Lee Seong‐Gwon , Lee Jong‐Wook
Published: September 2011

A Q‐band low‐noise amplifier (LNA) suitable for low‐voltage operation is presented in this paper.The amplifier uses a low‐voltage cascode structure in the first stage of the amplifier and was fabricated using a 0.13‐μm RF CMOS process with eight layers of copper metallization. Low‐voltage operation of the LNA was achieved in the millimeter‐wave band while still maintaining the high‐gain advantage of the cascode structure. Measured results show that the amplifier adopting the low‐voltage cascode structure provides similar gain to the conventional, telescopic cascode structure. The fabricated amplifier presented here achieves a 19.5‐dB small‐signal gain and a 7.5‐dB noise figure at 45 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2985–2988, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26389
Design of broadband transitions for substrate integrated circuits
Authors: Koziel Slawomir , Ogurtsov Stanislav
Published: September 2011

We present a methodology to enhance bandwidth of the conductor backed coplanar waveguide‐to‐substrate integrated waveguide and microstrip‐to‐integrated waveguide transitions.Our approach exploits metalized vias partially protruding into substrate in the transition region as tuning elements. This allows us—for the considered type of transition—to increase useable bandwidth. Geometry parameters, including positions and sizes of extra vias, are adjusted using simulation‐driven optimization procedure that exploits coarsely‐discretized electromagnetic (EM) models of the transitions and the adaptively adjusted design specifications technique. The optimal design is obtained at a low‐computational cost corresponding to a few high‐fidelity EM simulations of the structure of interest (typically comparable with the number of design variables). Our technique is demonstrated with the X‐band designs. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2942–2945, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26391
Closed‐form design method for broadband parallel‐coupled microstrip coupler with tight coupling and practical spacing
Authors: Abbosh Amin M.
Published: September 2011

A closed‐form method to design microstrip couplers that have tight coupling, practical dimensions, simple structure, and broadband performance is presented. The method is based on the quasi‐static even‐odd mode approach. According to the proposed method, three‐lumped capacitor connected at the center of the coupled structure are used to relax the requirement on the gap width between the coupled lines. The simulated and measured results of 3 dB couplers designed using the proposed method confirm its validity. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2790–2794, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26395
Electromagnetic analysis of planar array structures with MPIE–MoM method and neighborhood mutual coupling
Authors: Padilla de la Torre P. , Fernández J.M. , Sierra‐Castañer M.
Published: September 2011

An essential aspect when considering radiating array elements for simulation is to add the effect of the surrounding array cells in the analysis of the studied radiating element.The aim of this article is to present a complete mixed potentials integral equation solver including mutual coupling between elements in an array structure. The theoretical approach is presented along with some particular issues, in terms of programming and performance. Some canonical structures are analyzed in order to validate the developed electromagnetic tool and compared with commercial software. This electromagnetic tool has been built up for the analysis of antenna array structures and transmitarray lenses. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2746–2754, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26397
Broadband circularly polarized gap‐coupled arrangement of rectangular patches for modern communication systems
Authors: Sekra Pratibha , Shekhawat S. , Bhatnagar D. , Saxena V.K. , Saini J. S. , Joshi L. M.
Published: September 2011

The radiation performance of broadband circularly polarized gap‐coupled arrangement of rectangular patches is reported in this article. This arrangement of patches is designed on glass epoxy FR‐4 substrate. The considered structure consists of three rectangular patches having separation “d” between them. The central designed patch is excited through a single inset feed point while the other two patches are gap coupled to the central patch. After extensive optimizations, it is realized that the considered structure resonates at two closely spaced frequencies lying in the median band for the WiMax communication systems approved by IEEE 802.16 Working Group and presents nearly 12% impedance bandwidth. Additionally, the radiations are circularly polarized in nature, though the axial ratio bandwidth is narrow. The radiation patterns in the entire bandwidth are identical in nature. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2935–2939, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26398
A low phase noise oscillator with a high‐Q split ring resonator using MNG metamaterial
Authors: Yoon Ki‐Cheol , Lee Jong‐Chul
Published: September 2011

In this article, a novel high QL triple‐split ring resonator (T‐SRR) of mu‐negative metamaterial is suggested.It is used in the design of an I‐ band oscillator. A very low phase noise can be obtained for the oscillator due to the sharp band‐rejection characteristic of T‐SRR. The oscillator is designed to operate at 10 GHz using the novel T‐SRR. Experiments show that the output power is 9.82 dBm, the second harmonic suppression is −26.48 dBc, and the phase noise is −105.05 dBc/Hz at a 100‐kHz offset. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2967–2971, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26404
A 5.8‐GHz frequency synthesizer chip design for worldwide interoperability for microwave access application
Authors: Huang Jhin‐Fang , Shih Chun‐Wei , Liu Ron‐Yi
Published: September 2011

A 5.8‐GHz frequency synthesizer using wideband LC‐tank voltage‐controlled oscillator (VCO) for worldwide interoperability for microwave access applications with a 1.8 V voltage supply has been designed and successfully implemented in TSMC 0.18 μm CMOS process. In this proposed circuit, two important ideas are applied. First, a 3‐bit binary weighted capacitor array in the VCO is adopted to extend the tuning range and reduce the phase noise. Second, a class‐AB current mode logic is utilized in first divider stage to handle the high frequency signal. Measured results show that output frequency of VCO is tunable from 5.3 to 6.1 GHz corresponding to 14.1%, and phase noise is −110.2 dBc/Hz at 1 MHz offset, output power spectrum is −9.24 dBm at frequency of 5.73 GHz, power consumption is 32 mW, and including pads, chip area is 0.53 (0.82 × 0.65) mm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2931–2935, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26405
Wideband low‐noise amplifier design using the LC‐ladder and capacitive shunt–shunt feedback topology
Authors: Weststrate Marnus , Sinha Saurabh
Published: September 2011

The LC‐ladder and capacitive shunt–shunt feedback topology has been identified as a potential candidate for the implementation of wideband low‐noise amplifiers.This article presents a summary of the mathematical model describing this configuration and explains the improvement of the linearity which also results in reduced sensitivity to process variations. Simulated and preliminary measured results for a design using the IBM 7WL SiGe processes are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2922–2931, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26406
Application of microstrip cavity couplers for wideband bandpass filters
Authors: Cheng Jui‐Ching , Li Eric S. , Chuang Chin‐Chung
Published: September 2011

This article presents a design for wideband bandpass filters using a microstrip cavity coupler. The broadband nature of the cavity‐coupled designs is fully exploited for this application. Two additional circuits are introduced to improve the stopband performance of the cavity‐coupled bandpass filter. A prototype design example is presented with its center frequency located at 6.28 GHz. The design has the merits of wide bandwith of more than 140%, flat group delay within the passband, good insertion/return loss, and stopband attenuation of nearly 30 dB up to 30 GHz. The validity of the simulation results is verified experimentally. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2814–2817, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26410
Design of a compact multiband internal antenna for mobile application
Authors: Li Jianxing , Jiang Yansheng , Zhang Anxue , Chen Juan , Sheng Xiong
Published: September 2011

A compact multiband internal antenna for global system for mobile communication, digital cellular system, and wireless local area network services is proposed. The proposed antenna is composed of a multiple input and multiple output (MIMO) antenna and a dual‐band printed inverted F antenna. In particular, projected ground structure is adopted to improve isolation characteristic between the two elements of the MIMO antenna. The experimental results show that sufficient bandwidths, reasonable radiation patterns, and antenna gains are achieved for each frequency band. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2865–2868, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26413
Radiation measurement of 60 GHz high resistivity silicon on insulator double slot antenna
Authors: Barakat Moussa H. , Delaveaud Christophe , Ndagijimana Fabien
Published: September 2011

The performance of a 60 GHz folded‐slot antenna integrated on high resistivity silicon on insulator is described.The antenna is composed of a coplanar waveguide transmission line and the radiating slots. The slot antenna is folded and short circuited at its edge to optimize the 50 Ω matching impedance process. Backside substrate metallization has been used to improve radiation properties. A novel test method is used to measure the gain pattern of the dipole. The resulting measured radiation efficiency is 20% with a gain around −5.5 dBi at 60 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2861–2865, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26414
Erratum: Implementation of an efficient shooting and bouncing rays scheme
Authors: Dikmen Fatih , Ergin A. Arif , Sevgili A. Levent , Terzi Bilgin
Published: September 2011

Originally published Microwave Opt Technol Lett 52:2409–2413, 2010. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53: 2003, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26418 (Original article DOI 10.1002/mop.25492)
Circularly polarized annual ring antenna perturbed by asymmetrical defected ground structures for improved gain
Authors: Pyo S. , Lee M.‐J. , Lee H.‐S. , Kim S.‐H. , Kim Y.‐S.
Published: September 2011

A novel perturbing methodology using asymmetrical defected ground structure (DGS) is proposed for a circularly polarized (CP) annual ring antenna with improved antenna gain. By loading two fairs of half dumbbell‐shaped DGS at four diagonal corners of the ring radiator, the orthogonally polarized modes are controlled. Simulated and measured results show that the proposed antenna demonstrates good CP radiations at the resonant frequency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2994–2996, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26420
Low power and high conversion gain 21‐GHz receiver front end in a standard 0.18 μm CMOS technology
Authors: Chen Chi‐Chen , Lin Yo‐Sheng
Published: September 2011

This article describes a monolithic receiver front end comprising a low‐noise amplifier (LNA), a mixer, an intermediate‐frequency (IF) amplifier, and an IF filter implemented in a standard 0.18 μm CMOS technology.Current‐reused technique is used in the LNA to reduce power dissipation. Current bleeding technique is used in the mixer to improve conversion gain and power linearity. To enhance RF–IF and LO–IF isolation, an RC low‐pass filter (i.e., IF filter) is added in the drain terminal of the input transistor of the cascode IF amplifier. At an RF of 21 GHz and IF of 2.4 GHz, the receiver front end dissipated 43.2 mW and exhibited a noise figure (NF) of 8.6 dB, and a conversion gain of 20.3 dB. In addition, excellent isolation was also achieved. The measured LO–IF and LO‐RF isolation is −30.9 dB and −51.1 dB, respectively, at LOin of −1 dBm. The measured RF–IF isolation is −57.3 dB at RFin of −30 dBm. The chip area is only 0.97 × 0.9 mm2, that is, 0.873 mm2, excluding the test pads. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2875–2879, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26423
Compact dual‐mode bandpass filter using meander defected ground waveguide loop resonator
Authors: Liu Haiwen , Xu Wenyuan , Shen Li , Jiang Yang , Shi Liyun , Wan Jing , Lim Jongsik , Ahn Dal
Published: September 2011

To miniature the size of dual‐mode defected ground structure (DGS) resonator, novel meander defected ground waveguide resonator filter geometry is proposed in this letter. Its equivalent circuit structure and the coupling scheme are analyzed by even–odd mode theory. Defected corner‐cut perturbation is introduced to adjust the strength and nature of the coupling between the degenerate modes of this dual‐mode resonator. This filter with elliptic characteristics is designed, fabricated and measured. A good agreement between simulation and measurement verifies the validity of this design methodology. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2802–2805, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26425
A new technique for bandwidth improvement and size reduction of helical antennas
Authors: Alsawaha H. , Safaai‐Jazi A.
Published: September 2011

Novel modifications on axial‐mode wire helical antennas are introduced by replacing the wire with a tapered strip and using a doubly tapered impedance matching section.These modifications increase the bandwidth by 8% and reduce the helix height buy more than 0.6 wavelength. Simulation and measurement results are presented. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2990‐2994, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26427
Modified dual monopole antenna for WLAN operation
Authors: Seo Yongseok , Jung Jinwoo , Lee Hyeonjin , Lim Yeongseog
Published: September 2011

A novel and simple design of a coplanar waveguide‐fed folded dual monopole antenna with dual‐band frequency operation for a wireless local area network (WLAN) application is proposed. The obtained impedance bandwidths reach about 37.3% for the 2.4 GHz and 15.5% for the 5.8 GHz band, meeting the required bandwidth specifications of the IEEE 802.11a/b/g standards. The peak antenna gains for the operating frequencies across dual WLAN bands are measured to be 6.30 and 5.16 dBi, respectively. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2768–2770, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26428
Multiband double‐folded PIFA design for mobile applications
Authors: Sim Chow‐Yen‐Desmond , He Wen‐Bin
Published: September 2011

A compact size (15 × 40 mm2) microstrip‐fed printed planar inverted‐F antenna (PIFA) for mobile applications operating in the GSM/DCS/PCS/UMTS/WLAN and WiMAX bands is proposed. The main structure of this antenna is simply a double‐folded PIFA with two wide open‐ended radiating sections. By tuning the dimensions of the shorter open‐ended section, optimum impedance matching can be achieved, while additional slits loaded to the longer open‐end section are for the inclusion of universal mobile telecommunications system band. To allow shifting of the higher frequencies modes so that a wide impedance bandwidth from 5 to 6 GHz can be achieved, the technique of adjusting the position of the shorting post horizontally along the ground plane is also introduced. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2952–2960, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26429
A novel ultra‐wide band bandpass filter with notched band using slotline and microstrip resonators
Authors: Guan Xuehui , Chen Peng , Fu Wei , Liu Haiwen , Li Guohui
Published: September 2011

A novel ultra‐wide band bandpass filter with notched band is presented.Multi‐mode resonator is realized using a stepped‐impedance slotline. The resonator is orthogonally coupled to the microstrip feed lines, and ultra‐wide passband is obtained. Microstrip open loop resonators are loaded on the slotline, and notched band from 5.1 to 5.3 GHz is achieved. The filter is designed, fabricated, and measured. Good agreement is achieved between measured and predicted results. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2949–2951, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26430
Bipolar dual‐band MPRS‐FSS sectoral antenna for base station applications
Authors: Hajj M. , Toubet M. Salah , Chantalat R. , Monediere T. , Jecko B.
Published: September 2011

This article deals specifically with sectoral antennas and focuses on the ability to design a bipolar dual‐band structure by combining double layers metallic partially reflective surface (MPRS) working on orthogonal polarizations as a superstrate with a frequency selective surfaces (FSS) as a substrate , thus making it possible to circumvent the narrow bandwidth problem. The use of metallic structures offers a new approach to industrial partners to reduce costs and to facilitate design techniques. This antenna provides vertical and horizontal polarizations with a sectoral radiation pattern presenting a half power beamwidth of at least 60° in the azimuth plane. We obtain the different operating frequencies by adjusting the distance of MPRS layers from FSS layer. The proposed structure presents more than 15 dBi directivity enhancement at 4.8 and 5.6 GHz as compared to those of a patch antenna with 8 dB directivity. The geometry and characteristics of the antenna are detailed and a design method is proposed. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2907‐2912, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26431
High‐performance low‐power 27‐GHz CMOS voltage‐controlled oscillator for Ka‐band applications
Authors: Yeh Mei‐Ling , Lin Yao‐Chian , Chang Chung‐Cheng
Published: September 2011

A new low‐power 27.07‐GHz voltage controlled oscillator is designed for Ka‐band applications in this article. Body bias technique is used for the low‐power and low‐phase noise VCO design. The VCO can be tuned from 26.35 to 27.102 GHz. The measured phase noise is −106.2 dBc/Hz at 1 MHz offset from the carrier frequency. The corresponding figure‐of‐merit (FOM) is calculated to be −183.2 dBc/Hz. The VCO is implemented with the TSMC 0.18 μm one‐poly‐six‐metal 1.5 V mixed signal/RF CMOS technology. The chip size is 0.565 × 0.69 mm2. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2872‐2875, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26433
Electromagnetic inversion with the multiscaling inexact Newton method—experimental validation
Authors: Randazzo Andrea , Oliveri Giacomo , Massa Andrea , Pastorino Matteo
Published: September 2011

The integration of the inexact Newton method within a multiscaling strategy is assessed in the framework of the contrast‐field formulation of the electromagnetic inverse scattering. By using the features of the integrated approach, the technique is expected to suitably face the nonlinearity and the illposedness/ill‐conditioning issues of the imaging problem. A numerical validation dealing with experimental data related to different objects is carried out to provide evidence of the method premises pointing out features and potentialities as well as current limitations. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2834–2838, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26435