bluuebunny/crossref_metadata_2025 huggingface dataset:
Concrete cover cracking owing to reinforcement corrosion – theoretical considerations and practical experience
Authors: Angst U. , Elsener B. , Jamali A. , Adey B.
Published: October 2015

Reinforcement corrosion might lead to cracking and spalling of the concrete cover owing to the volume expansion associated with the deposition of some of the possible corrosion products. This is not only aesthetically unpleasing, it might also accelerate deterioration processes or become a safety issue for passing traffic. The present paper discusses first the mechanisms of carbonation‐ and chloride‐induced reinforcement corrosion and considers the chemistry of aqueous iron in order to identify the type of corrosion products as well as their location of formation. Furthermore, practical examples are summarised in order to compare the documented behaviour of a number of real structures with the theoretical considerations made. It is shown that for the case of purely chloride‐induced (pitting) corrosion, precipitation of corrosion products is strongly delayed or may even not occur. Implications are discussed with respect to time‐to‐corrosion prediction models and visual inspection of reinforced concrete structures. Both the theoretical considerations and the practical experience illustrate that relying on outwardly visible signs to detect internally on‐going corrosion must be done with caution if localised reinforcement corrosion cannot be excluded.
Long‐time behavior of non‐galvanized and galvanized steels for geotechnical stabilization applications
Authors: Nürnberger U.
Published: October 2015

The contribution is dedicated to the durability of geotechnical stabilization applications. The long‐term corrosion behavior of unprotected and galvanized thread‐bars for micro‐piles and nails in different soils is described. The bars in the ground are embedded in an up to 20 mm thick cement mortar, which may be cracked and locally destructed. First, the corrosion‐affecting parameters of the steel corrosion in the ground are described and soil classes are defined. Furthermore, an estimation of the long‐term (up to 50 years) corrosion behavior was assessed on the base of information from the literature. Here the corrosion of the thread‐bar in direct contact with the soil was in the center of interest. The corrosion protection of the cement mortar cover was not taken into consideration, in order to be on the safe side. On the other hand, a macrocell‐corrosion of the thread‐bars cannot be completely excluded, if the cement mortar casing exhibits defects and constructional and environmental corrosive conditions in the ground are fulfilled. Two cases are discussed:

• element formation between sections along the thread‐bar,

• element formation between the thread‐bar and other reinforced concrete parts.
Alternating current corrosion of cathodically protected pipelines: Discussion of the involved processes and their consequences on the critical interference values
Authors: Büchler M.
Published: October 2015

Based on laboratory studies and model concepts, a profound understanding of the involved processes in ac corrosion and the required limits has been obtained in the last years. But there was no information whether these thresholds can be effectively applied to pipelines or whether operational constraints make their implementation impossible. Therefore, an extensive field test was carried out. Thereby, the relevance of the laboratory tests for field application could be demonstrated and all threshold values were confirmed. Detailed analysis made it possible to explain the observed threshold values based on thermodynamic and kinetic considerations. The results summarized in the present work are the basis for the normative work defining the thresholds for the operation conditions of cathodically protected pipelines.
Effect of exposure in steam or argon on the creep properties of Ni‐based alloys
Authors: Dryepondt S. , Unocic K. A. , Pint B. A.
Published: October 2015

Although expensive, Ni‐based superalloys are of interest for the ultrasupercritical steam program because of their good creep and oxidation resistance at temperatures above 700 °C. As the effect of steam oxidation on the alloy mechanical properties is unknown, creep specimens of alloy CCA617, 740, and 230 were pre‐oxidized for 2000 and 4000 h in steam at 800 °C before testing in air at the same temperature. Compared with as fabricated material, exposure in steam decreased the creep properties of alloy CCA617, had less of an effect on alloy 740, and did not affect alloy 230. Testing of a specimen repolished after steam exposure as well as microstructural observations indicate that the oxidation affected zone at the specimen surface is not responsible for the properties degradation. Surprisingly, a similar time anneal in an inert environment resulted in a drastic decrease of creep rupture life and an increase in the creep rate and elongation at rupture. Transmission electron microscopy analysis revealed that the mechanical properties decrease for alloy CCA617 is related to the absence of γ′ precipitates within the grains.
Effect of nano‐particulate sol–gel coatings on the oxidation resistance of high‐strength steel alloys during the press‐hardening process
Authors: Yekehtaz M. , Klesen C. , Benfer S. , Bleck W. , Fürbeth W.
Published: October 2015

The need for lighter constructional materials in automotive industries has increased the use of high‐strength steel alloys. To enhance passenger's safety press hardening may be applied to steel parts. However, as the steel parts are heated up to 950 °C during this process they have to be protected by some kind of coating against the intense oxide formation usually taking place. As the coating systems used so far all have certain disadvantages in this work the ability of nano‐particulate thin coatings obtained by the sol–gel process to improve the oxidation resistance of 22MnB5 steel is investigated.

The coatings obtained from three sols containing lithium aluminum silicate and potassium aluminum silicate showed the best performance against oxidation. The structural properties of the coating materials were characterized using different methods like XRD and differential thermal analysis. Comparison of the oxidation rate constants proved the ability of the coatings to protect against oxidation at temperatures up to 800 °C. Press‐hardening experiments in combination with investigations on the thermal shock resistance of the coated samples also showed the ability of the coatings to stay intact during press hardening with only slight spalling of the coatings in the bending areas. The absence of any secondary intermetallic phases and layer residues during laser beam welding experiments on coated samples proves the suitability of the nano‐particulate coatings for further industrial processing.
On the importance of execution for obtaining the designed durability of reinforced concrete structures
Authors: Geiker M. R.
Published: October 2015

The design and execution of reinforced concrete structures shall together with planned maintenance lead to the intended level of safety and serviceability during the entire service life of the structure. The possible impact of execution on the performance of the finished concrete structure is not always recognized; e.g., is pre‐testing of alternative mixes often undertaken at laboratory conditions. Mix design should include an assessment of the stability and property development of the concrete at the anticipated execution conditions as well as an evaluation of the robustness of the concrete to natural variations in mix composition and execution. Through selected examples the paper addresses the importance of execution for obtaining the designed performance and durability of reinforced concrete structures.
Present and future durability challenges for reinforced concrete structures
Authors: Angst U. M. , Hooton R. D. , Marchand J. , Page C. L. , Flatt R. J. , Elsener B. , Gehlen C. , Gulikers J.
Published: October 2015

This paper sums up the International RILEM Workshop on Present and Future Durability Challenges for Reinforced Concrete Structures, held at ETH Zurich in Switzerland on 17–18 April 2012. Major focus is put on the discussions. During the latter it was revealed that one of the key durability challenges lies in predicting the performance of new materials, where the increasing diversity of cement and concrete plays a major role. As most current engineering models are not capable of predicting actual field performance adequately, a knowledge‐based approach to durability will become more important than ever. Only a scientific approach on a multi‐scale and interdisciplinary level will allow predicting the performance of new materials (where no long‐term experience is available for fitting purposes). This will facilitate the use of more performance‐based durability design that is urgently needed to promote innovative, long‐lasting solutions.
Materials and Corrosion 8/2012
Authors: Kovač J. , Marrow T. J. , Govekar E. , Legat A.
Published: October 2015

Cover: Development of stress‐corrosion cracking with time is presented by sequences of four images. Development of strain on the surface of the specimen can be effectively evaluated and presented by digital image correlation analysis (DIC). The level of intensity of strain in horizontal direction is presented by blue‐green‐yellow‐red‐white (increasing scale) colours. This analysis can be further used for detection of cracks and for quantitative evaluation of crack lengths and crack opening displacements.

More detailed information can be found in: J. Kovač, T. J. Marrow, E. Govekar, A. Legat, Detection and characterization of intergranular stress‐corrosion cracking on austenitic stainless steel, Materials and Corrosion 2012, 63, 664.
Materials and Corrosion 9/2012
Authors: Yasir M. , Mori G. , Wieser H. , Reller A. , Höppel H. W.
Published: October 2015

Cover: Sensitization in stainless steels is associated with precipitation of chromium rich carbides along grain boundaries during the detrimental heat treatments. This phenomenon was also found in automotive exhaust applications. Some commonly used grades were investigated during a research project. The precipitation of chromium carbides were observed with high resolution techniques like SEM and TEM.

More detailed information can be found in: M. Yasir, G. Mori, H. Wieser, A. Reller, H. W. Höppel, Study of sensitization and different heating cycles on stainless steels used for automotive exhaust components, Materials and Corrosion 2012, 63, 763.
Materials and Corrosion 11/2012
Authors: Bozzini B. , Barella S. , Bogani F. , Giovannelli G. , Natali S. , Scarselli G. , Boniardi M.
Published: October 2015

Cover: A multi‐technique approach featuring electrochemical measurements (LSV and EIS), in plane and cross‐sectional metallography, EDX mapping and XRD yields a notable insight into the corrosion of austenitic (AISI304) and duplex (2205) stainless steels in molten KOH/NaOH 50 w/o eutectic at 250°C.

AISI304 – to which the results reported in the cover refer – exhibits a pseudo‐passivating behaviour while duplex undergoes generalised corrosion. As a function of applied potential, the pseudo‐passivating scales forming on AISI304 contain both corrosion products and electrolyte species.

More detailed information can be found in: B. Bozzini, S. Barella, F. Bogani, G. Giovannelli, S. Natali, G. Scarselli, M. Boniardi, Corrosion of stainless steel grades in molten NaOH/KOH eutectic at 250°C: AISI304 austenitic and 2205 duplex, Materials and Corrosion 2012, 63, 967.
I Know What I Know, but I will Probably Fail Anyway: How Learned Helplessness Moderates the Knowledge Calibration–Dietary Choice Quality Relationship
Authors: Hansen Torben , Thomsen Thyra Uth
Published: October 2015

Prior research suggests that knowledge calibration (KC) supports consumers’ maintenance of a healthy diet. However, no previous studies have considered that learned helpless consumers may refrain from using their knowledge, even though they may be fully aware that they possess it. This research gap is considered in three studies. Study 1 investigates the moderating effect of learned helplessness (LH) by means of a cross‐sectional survey. Studies 2 and 3 are online choice studies. Besides from replicating Study 1, Studies 2 and 3 eliminate potential social desirability bias by objectively measuring respondents’ dietary choice quality. In addition, Study 3 takes into account the possibility that respondents’ responses may be biased by food preferences, medical conditions, and/or food allergies. Moreover, Studies 2 and 3 both investigate the consequences of the findings on consumers who live under a dieting regime. These studies demonstrate that consumers suffering from LH do not stand to gain from calibrating their dietary knowledge to the same degree as other consumers. It is also shown that dieting behavior has a tendency to weaken this negative moderating effect of LH on the relationship between KC and dietary choice quality. Finally, the implications of the findings for marketers and public policymakers are discussed.
Downregulation of nitrogen permease regulator like‐2 activates PDK1‐AKT1 and contributes to the malignant growth of glioma cells
Authors: Huang Ning , Cheng Si , Mi Xiujuan , Tian Qin , Huang Qin , Wang Feng , Xu Zongye , Xie Zongyi , Chen Jin , Cheng Yuan
Published: October 2015

Nitrogen permease regulator like‐2(NPRL2) is a candidate tumor suppressor gene(TSG) located on chromosome 3p21.3 and deletions frequently occur in this region, leading to canceration. Recently, molecular pathologic researches have provided valuable insights into the downregulation of NPRL2 in carcinogenesis in some types of cancers. However, very little is known about genetic changes of NPRL2 involved in glioma. Here, for the first time, we aimed to understand the expression levels, functions and mechanisms of NPRL2 for progression of glioma. We clearly demonstrated that NPRL2 expression was decreased in glioma and was negatively correlated with the histologic grade. The upregulation of NPRL2 expression in glioma cells inhibited proliferation by inducing G0/G1 cell cycle arrest in vitro and suppressed the growth of xenotransplanted tumors. In contrast, siRNA‐mediated knockdown of NPRL2 promoted glioma growth. The anti‐cancer effects of NPRL2 were involved in dephosphorylation of PDK1Tyr9 and downstream AKT1Thr308 resulting in inactivation of the PDK1‐AKT1 signaling pathway, this ultimately increased the expression of p21 and p27, and inactivated CDK2 and CDK4. Our data confirmed NPRL2 was downregulated in gliomas. More importantly, NPRL2 was able to inhibit cell proliferation in vitro and repress tumorigenicity in vivo, suggesting its role as a tumor suppressor. Our data provide a basis for the further development of a promising therapeutic target for glioma. © 2015 Wiley Periodicals, Inc.
OnabotulinumtoxinA and AbobotulinumtoxinA Dose Conversion: A Systematic Literature Review
Authors: Dashtipour Khashayar , Chen Jack J. , Espay Alberto J. , Mari Zoltan , Ondo William
Published: October 2015

Objective

This systematic review was performed to elucidate dosing practices, dosing conversions, and related outcomes from randomized, controlled trials that directly compared onabotulinumtoxinA (ONA) and abobotulinumtoxinA (ABO) at various dose conversion ratios for therapeutic use in movement disorders.

Methods

A systematic review of three medical literature databases (PubMed, the Cochrane Library, and EMBASE) was performed to identify relevant comparative clinical studies, systematic reviews, and meta‐analyses published in the English language between January 1991 and January 2015. Studies that met predefined inclusion criteria were selected for formal data extraction and quality assessment.

Results

A total of 182 manuscripts were identified, of which four were included for analysis. Targeted clinical applications included neurological disorders. The studies compared ONA to ABO dose conversion ratios of 1:2.5 (n = 1), 1:3 (n = 2), and 1:4 (n = 2). One study compared both 1:3 and 1:4 ratios. An ONA:ABO conversion factor of 1:2.5 was associated with similar efficacy and side effects. An ONA:ABO ratio of 1:3 provided similar or higher efficacy, but an increased rate of adverse effects, and an ONA:ABO ratio of 1:4 was associated with higher efficacy, but with an excessive rate of intolerable side effects.

Conclusion

A dose conversion ratio of ONA to ABO between 1:2.5 and 1:3.0 provides comparable safety and efficacy for therapeutic movement disorders chemodenervation procedures.
An active strain sensing system based on single‐longitudinal‐mode distributed Bragg reflector fiber laser and its applications in the measurement of erbium‐doped fiber birefringence
Authors: Zhang Hao , Liu Bo , Jia Chenglai
Published: October 2015

An active strain sensing system based on single‐longitudinal‐mode distributed Bragg reflector fiber laser is proposed and experimentally demonstrated. Owing to the short laser cavity length and birefringence‐induced mode splitting, the proposed laser in single‐longitudinal‐mode operation provides a beat signal from 1.598 to 2.53 GHz as the strain applied onto the fiber laser changes, and through beat frequency interrogation the proposed laser sensor turns out a strain sensitivity of ∼0.21 MHz/με. Moreover, by simultaneously monitoring the laser wavelength and beat frequency, strain dependence of erbium‐doped fiber birefringence has also been measured, and experimental results show that erbium‐doped fiber birefringence has a strain sensitivity of ∼1.59 × 10−9/με. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2508‐2512, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26302
Miniaturized size of dual‐band‐meandered branch‐line coupler for WLAN application
Authors: Jizat N. M. , Rahim S.K. A. , Rahman T. A. , Abdulrahman A. Y. , Sabran M. I. , Hall P. S.
Published: October 2015

A new method of a dual‐band miniaturized branch‐line coupler (BLC) is presented with two widely separated bands (f2 > 2f1) for wireless local area network application. Partially meandered lines are used as the coupler's shunt arms; and are designed to operate at f1 = 2.45 GHz and f2 = 5.8 GHz. There are 65 and 90% reduction in circuit area compared to the previous research design. Theoutput signal ports have an equal power split within measurement accuracy and 2° error at the resonant frequencies. The simulated and measured results are in good agreement, thereby verifying the design concept. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2543–2547, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26312
Design, implementation, and measurements of a novel broadband dual‐polarized patch array in Ku band for polarimetric SAR systems
Authors: Sánchez‐Sevilleja S. , Larrañaga‐Sudupe J. R.
Published: October 2015

A novel compact broadband and dual‐polarized Ku‐band synthetic aperture radar (SAR) antenna with a high level of isolation between polarizations has been developed by INTA Radar Laboratory as an advanced sensor for the QUASAR project, which involves INTA new SAR developments for small platforms and unmanned aerial vehicle (UAV). The antenna design is composed by a 4 × 8 dual‐polarized square patch array fed through a very efficient and novel structure based on a cross‐shape slot to achieve a large bandwidth and overall to achieve an excellent isolation between polarizations needed in a polarimetric system such as the one INTA has developed. Finally, the antenna must be placed inside a pod which is going to be placed under the UAV wings, so the antenna must be lightweight, robust, and with small size. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2537–2543, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26313
Radiated susceptibility of medical equipment in health care units: 2G and 3G mobile phones as an interferer
Authors: Helhel Selcuk , Ozen Sukru , Basyigit I. Bahadir , Kurnaz Osman , Yoruk Yunus E. , Bitirgan Murat , Colak Zeynep
Published: October 2015

Mobile phones have been started to be in concern as an electromagnetic interference source in hospitals in Turkey as well as other countries. There are about 50 million subscribers in the country that each patient can be assumed as a mobile phone holder, and they always want to be in service. Meanwhile, hospital buildings are very huge buildings which are not allowing deep radio penetration through the holes. While weak signal coverage level allows mobile phones camping on operator, it forces mobiles to operate at its maximum power level of 2 W. While ANSI C63.18 offers safety distances (m) for medical devices for mobile phone usage, this study points out that output power (equivalently distance) cannot be a reason itself. This phenomenon has been examined by three‐dimensional electromagnetic field distribution measurement through the health units. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2657–2661, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26321
Low‐power 2.4/5.15‐GHz dual‐band voltage‐controlled oscillator
Authors: Miao Yannan , Chye Boon Chirn , Anh Do Manh , Seng Yeo Kiat , Zhang Yuxiang X.
Published: October 2015

We proposed a 2.4/5.15 GHz dual‐band voltage‐controlled oscillator which consists of a voltage‐controlled oscillator and an injection‐locked oscillator. Its upper and lower band frequencies are 4.48∼5.86 GHz and 2.24∼2.93 GHz, respectively. With the power consumption of 3.2 mW, their phase noises are −115 and −121 dBc/Hz at 1 MHz offset. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2495–2497, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26329
CMOS direct injection‐locked frequency divider (3.55 mW 80 GHz) with 26.3% locking range using distributed LC tank and body bias techniques
Authors: Wang Chien‐Chin , Chen Chang‐Zhi , Lin Yo‐Sheng
Published: October 2015

A 3.55‐mW 80‐GHz complementary metal‐oxide‐semiconductor (CMOS) divide‐by‐2 direct injection‐locked frequency divider (DILFD) using distributed inductance‐capacitance (LC) tank and body bias techniques for operation frequency and locking‐range enhancement is demonstrated.Compared with the traditional LC tank, the distributed LC tank significantly decreases the equivalent LC and C values. This in turn results in an increase of the operation frequency and the locking range. In addition, trans‐conductance (gm) of the injection transistor can be improved by body bias due to the reduction of its threshold voltage. This in turn results in an increase of the locking range (6.2 GHz in simulation). Furthermore, power consumption is reduced by eliminating the head current source in the traditional DILFD. Measurement result shows the proposed DILFD achieved a state‐of‐the‐art 26.3% (61.5–80.1 GHz) locking range and an excellent output phase‐noise of −128.69 dBc/Hz at 1 MHz offset. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2694–2697, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26333
A novel design of organic semiconductor thin film device embedded microstrip antenna
Authors: Teng Hsien Chiao , Cherng Shen , Huang Yu‐Jung
Published: October 2015

Implanting an organic semiconductor thin film (OSTF) device into an inexpensive FR4 substrate to design a microstrip antenna is demonstrated in this article. When the substrate was grounded for the device, special features of the frequency dependent I–V curves and the PN junction built‐in potential formed by joining of C60 (n‐type) and CuPC (p‐type) OSTFs can be obtained. The device can thus be activated and excited as a microstrip antenna by the side probe‐fed simultaneously. Meanwhile, the antenna gains can be modified by changing the thin film thickness as well as the source voltage of probe‐fed to excite the resonated mode of the structure of the microstrip antenna. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2569–2572, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26338
Folded substrate integrated waveguide cross‐coupled filters with negative coupling structure for wireless systems
Authors: Glubokov O. , Nagandiram S. , Tarczynski A. , Budimir D.
Published: October 2015

In this article, a compact multilayer substrate integrated filter with pseudoelliptic power transfer function is presented. The fourth‐order bandpass filter designed by optimization has a central frequency of 10 GHz with a bandwidth of 800 MHz. It possesses two transmission zeros and exhibits return loss of −30 dB. Miniaturization is achieved using folded waveguide technology. Novel negative coupling structure based on upside–down‐folded iris‐coupled resonators is introduced and investigated. Design procedure is briefly explained, coupling matrix is derived, and investigation of coupling elements is carried out to match calculated coupling coefficients. Results of full‐wave simulation of the filter are in good agreement with the prototype. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2521–2526, 2011; Published online in View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26341
Compact dual‐band‐printed dipole antenna with parallel‐winding lines and tapered structure for WLAN applications
Authors: Zhang Na , Jing Wang Yang , Wei Shi Xiao
Published: October 2015

In this article, a compact printed dipole antenna for wideband local area network (WLAN) (2.45/5.5 GHz) applications is presented.The proposed antenna consists of two radiating patches with several slots etched on the patches, which can generate parallel‐winding lines and then produce two bands. By using the unique tapered structure, good impedance matching can be achieved in a wide dual‐band without external matching circuit. For the experimental study, the antenna provides 10.2% bandwidth from 2.325 to 2.575 GHz and 64.9% bandwidth from 3.225 to 6.325 GHz (RL ≤ −10 dB). In addition, the antenna has good omnidirectional radiation patterns in H‐plane and low cross‐polarization levels in both E‐ and H‐planes. The measured results are in good agreement with the simulation ones, and the experiment validates the design concept. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2492–2494, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26342
Alternating‐direction explicit scheme for the 2D finite‐difference time‐domain method for TEz waves
Authors: Fu Ping , Chen Ru‐Shan
Published: October 2015

In this article, a new explicit finite‐difference time‐domain (FDTD) method is proposed to eliminate the Courant–Friedrich–Levy (CFL) condition restraint. This new algorithm is based on an alternating‐direction explicit (ADE) method and Crank–Nicolson (CN) scheme. Called CN‐ADE‐FDTD method, and we present two versions of the proposed method. Numerical stability analysis of the new algorithm was also presented. Furthermore, the results by the CN‐ADE‐FDTD method are compared with the results by the conventional FDTD method. As a result, it is confirmed that the proposed method is unconditionally stable and superior to the conventional one. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2689–2694, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26346
Discontinuous Galerkin implementation of time‐domain finite‐element method using Crank–Nicolson scheme and complex frequency‐shifted perfectly matched layers for efficient analysis of dielectric loaded waveguide structures
Authors: Ye Zhenbao , Wang Chao‐Fu
Published: October 2015

This article presents the development of discontinuous Galerkin time‐domain finite‐element method (DG‐TDFEM) for modeling wideband electromagnetic response of dielectric loaded waveguide structures.The method can be considered as a kind of domain decomposition method. The hierarchical vector basis functions are used to expand the electric and magnetic fields in order to maintain high order accuracy and Crank–Nicolson difference scheme is utilized for the time‐partial equation for each subdomain. Both the electric and magnetic fields are computed in each subdomain, and only the fields on the interfaces of adjacent subdomains are directly related to each other. Thus, there is no need to solve a global matrix equation related to all boundary values. The complex frequency‐shifted perfectly matched layers are used for the truncation of unbounded solution region. Several three‐dimensional cavity and waveguide structures with dielectric loading are simulated to demonstrate the accuracy and efficiency of the proposed method. Compared to the original single‐domain problem, the size of each subdomain problem is reduced to result in a dramatic reduction of factorization time, as well as the overall computational time and peak memory usage. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2635–2642, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26349
A reusable coplanar waveguide probe for in situ material characterization
Authors: Everett Evan J. , Wentworth Stuart M. , Garrett Benjamin T.
Published: October 2015

A novel reusable coplanar waveguide tee resonator probe is stenciled in a rigid sheet of brass. The probe can be easily placed on dielectric slabs for in situ permittivity measurement. The method can be applied to inhomogeneous materials that may not lend themselves to precise sample preparation or to open‐ended coaxial probing. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2601–2604, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26350
High‐power effects in damaged and contaminated optical fiber connectors
Authors: Domingues Fátima , Rocha Ana M. , André Paulo S.
Published: October 2015

The optical fibers are key components for the high‐capacity telecommunications networks.The characteristics of physical contact optical connectors deteriorate when the fiber connector interface is contaminated or physically damaged, causing fatal failure or the performance degradation. In this work, we study the temperature and power‐loss behavior for contaminated and physically damaged optical connectors, under high optical power regime. The results indicate that the connector lifetime when subjected to high propagation powers, depends essentially on its cleanness rather than the surface degradation resulting from the plugging/unplugging operations. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2485–2488, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26356
Environment‐independent liquid level sensing based on fiber‐optic displacement sensors
Authors: Yang H. Z. , Harun S. W. , Arof H. , Ahmad H.
Published: October 2015

A new fiber‐optic liquid‐level sensor (LLS) for continuous monitoring of the liquid level is proposed using a fiber‐optic displacement sensor (FODS). A float is used to measure the level of liquid in the tank and it is connected to the FODS probe to convert the variation of the liquid level into a displacement change. The performance of the LLS is investigated for two different FODSs with a concave and a flat mirror target. With a concave mirror, six measurement slopes within a range of 25 mm are observed with the highest sensitivity of 1.3015 mV/mm. With a flat mirror, two measurement slopes are observed with the highest sensitivity of 1.4533 mV/mm and the longest measurement range of 4.8 mm. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2451–2453, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26358
Hybrid superelliptic horn
Authors: Malherbe J. A. G.
Published: October 2015

The waveguide horn with elliptic flare has been shown to exhibit superior radiation and impedance properties. In this article, a horn is described that flares with a hybrid superelliptical profile. The radiation patterns in the principal planes are identical up to the ‐10‐dB points. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2713–2716, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26360
Design of modified ground square‐shaped fractal antenna for UWB applications
Authors: Kumar Raj , Hake Shahadev
Published: October 2015

This article presents the design of modified ground square‐shaped fractal antenna. The prototype antenna is designed and fabricated on FR4 substrate of dielectric constant εr = 4.3 and thickness h = 1.53 mm. The proposed antenna is excited using coplanar waveguide feed. The experimental result of square‐shaped fractal antenna exhibits the excellent ultra‐wideband (UWB) characteristic corresponding to impedance bandwidth of 148.13 % from 2.235 to 15.0 GHz, exceeding Federal Communication Commission (FCC) frequency range with a return‐loss performance S11 = −10 dB. The simulated results are in good agreement with the experimental results. The experimental radiation patterns of this square‐shaped fractal antenna are omni‐directional in H‐plane and bidirectional in E‐plane. This proposed antenna can be useful for UWB system, microwave imaging and vehicular radar. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:2589–2592, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26365
Dual Band‐Notched Rectangular Monopole Antenna for Ultra Wideband Applications
Authors: Indu A. K. Gautam , Kanaujia Binod Kr
Published: October 2015

A compact microstrip fed monopole antenna with dual band‐notch function is proposed for ultrawideband applications. The antenna consists of a rectangular radiating patch one side and solid ground up to the half length of the antenna on the other side. The band notch functions are achieved by etching two back‐to‐back C‐shaped slot in the rectangular metal radiating patch. Combination of each notch element on the UWB antenna is aimed for providing dual band rejection function at WLAN 2 (5.15–5.825 GHz) and ITU 8 GHz (8.025–8.4 GHz). The measured results reveal that the presented dual band‐notch monopole antenna offers a very wide bandwidth with two notched bands from 5.2 to 5.96 GHz and 7.84 to 8.4 GHz. The prototype with overall size of 26 × 32 × 762 mm3 achieves good impedance matching, voltage standing wave ratio, constant gain, and stable radiation patterns, over an entire operating bandwidth of 2.8–12.16 GHz. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3029–3033, 2013
Multiband Frequency Selective Surfaces with Simple Modification of a Rectangular Patch Element
Authors: Campos A. L. P. S. , Silva T. L. , Gomes Neto A.
Published: October 2015

A simple modification in a rectangular patch element is exploited to design frequency selective surfaces (FSS) for multiband bandstop filter operation. The use of the modified rectangular patch elements enables the adjustment of FSS parameters (resonant frequency and −10‐dB bandwidth) according to the length and position of the slot but without modifying their original size. Transmission properties of proposed FSS are characterized by means of simulations and measurements. Four FSS prototypes were fabricated and measured. The obtained results show an interesting multiband behavior. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2943–2946, 2013
A Compact Dual‐Mode Dual‐Band Bandpass Filter Using Stepped‐Impedance Open‐Loop Resonators and Center‐Loaded Resonators
Authors: Yao Z. , Wang C. , Kim N. Y.
Published: October 2015

In this article, a compact dual‐mode dual‐band bandpass filter is proposed by using two modified stepped‐impedance open‐loop resonators and center‐loaded bars. The dual‐mode resonators are created by loading two center‐loaded bars, and this process is investigated through dual‐mode filter analysis. The external quality factor and the coupling coefficient is introduced and analyzed to optimize the proposed filter. A low insertion loss and high return loss dual‐mode dual‐band filter is designed and fabricated with a compact structure. Three transmission zeros are created near the passband, leading to a high selectivity. Two passbands are centered at 3.88 and 5.35 GHz with an insertion loss of −0.38 and −1.03 dB, respectively, and 3‐dB fractional bandwidths of 12.4 and 8.6% are obtained. The measured return loss is higher than −24.28 and −19.33 dB at the two resonant frequencies, respectively. The simulated and measured results are in good agreement, which verifies the design methodology. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3000–3005, 2013
Balanced Single Photon Avalanche Detector with Variode‐Based Spike Noise Cancellation
Authors: Zhang Yixin , Xie Fei , Yang Guowen , Zhang Xuping , Wang Shun
Published: October 2015

Spike noise cancellation is important for high‐speed single photon avalanche photodiode. In this article, we demonstrated a balanced single photon detector at 1.5 μm that contains one InGaAs/InP single photon avalanche photodiode and one matched variode. Suppression ratio of 27 dB can be achieved. At 253 K, detection efficiency of 13.9% is obtained with 1.06 × 10−5 per gate dark count probability and 4.3% after‐pulse probability at 100 MHz gating frequency. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2877–2879, 2013
A Quadruple‐Band CPW‐Fed Raster‐Shaped Monopole Antenna
Authors: Naser‐Moghadasi M. , Asadpor L. , Sadeghzadeh R. A.
Published: October 2015

A miniaturized quadruple‐band antenna with raster‐shaped patch is proposed. The proposed antenna can generate four separate impedance bandwidths to cover the 1.710–1.885, 1.850–1.990 GHz GSM operating bands, 2500–2690 GHz Extended UMTS operating band, 3650–3700 GHz and the 5.150–5825 GHz Wi‐Fi/Wireless Local Area Network (WLAN) band frequencies. The proposed coplanar waveguide‐fed antenna mainly consists of simple rectangular ground plane and developed raster‐shaped patch, which perform important role to produce all of four frequencies band. The designed antenna has a small overall size of 25 × 25 mm2 and operates over the frequency ranges, 1.7–1.97 GHz, 2.45–2.8 GHz, 2.94–3.68 GHz, and 5.1–6.2 GHz suitable for GSM, Extended UMTS and Wi‐Fi/WLAN application. There is good agreement between the measured and simulated results. Experimental results show that the antenna gives monopole‐like radiation patterns and good antenna gains over the operating bands. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3014–3018, 2013
A Compact CPW‐Fed Wide‐Slot Ultrawideband Antenna with Sharp Frequency Rejection Functions for Wlan Band and X‐Band
Authors: Li Yingsong , Li Wenxing , Yu Wenhua
Published: October 2015

In this article, a coplanar waveguide (CPW)‐fed ultrawideband (UWB) antenna with two sharp frequency rejection functions is proposed. The dual band‐notched characteristic is realized by etching a stepped impedance split‐ring resonator (SISRR) and a stepped impedance resonator (SIR) in a circular radiating patch and a CPW transmission stripline, respectively. The central frequency of the two notch bands can be controlled by adjusting the SISRR and the SIR parameters. Simulation and experimental results obtained for this antenna show that it exhibits a good radiation behavior within the UWB frequency range and it also has the dual band‐notched characteristics in the wireless local‐area networks band and X‐band, which can mitigate the potential interference between UWB systems and the designated existing narrow‐band systems. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2972–2976, 2013
A Compact Multiband and Wideband Bioinspired Antenna for Wireless Mobile Devices
Authors: Ebnabbasi Khabat , Mohebbi Marjan
Published: October 2015

A compact multiband and wideband biologically inspired antenna with a shape borrowed from the creatures with curved antennae is presented. The radiator is symmetric coplanar striplines modeled based on a stepped Chebyshev transformer. The designed steps are smoothed through curve fitting. The flare's opening rate is set using the software to achieve the required resonant frequency. Multi tapers are used in order to enhance the impedance bandwidth and the coverage of wireless bands. Depending on the flare's opening rates multiband or wideband designs are resulted. The validity of the method is verified through simulations and measurements of an experimental design example. The fabricated antenna's center frequency is 2.4 GHz and the substrate is FR‐4 with a dielectric constant 4.35 and thickness of 3.2 mm. The proposed design covers the WiBro, wireless local area network, and Bluetooth bands. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3019–3022, 2013
Effects of Variation of the Substrate Thickness of Rectangular Slot Resonator with Multilayer
Authors: Caetano Leonardo M. , Neto Marinaldo P. S. , Andrade Humberto D. , Fernandes Humberto C. C. , Maia Hugo Michel C. A.
Published: October 2015

This article presents a numerical and experimental analysis of rectangular slot resonators with multilayer of substrates. The transverse transmission line method, to determine the resonant frequency, was used. Optimization was performed starting of numerical analysis and the proposed device designed for a frequency of 3.31 GHz. Through an experimental investigation carried out, an analysis of the simulated versus measured was observed. The behaviors of the characteristic radiation with the variation of the height of the dielectric substrates are analyzed, presenting good results. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2931–2938, 2013
Neural Network Based Resonant Frequency Solver for Rectangular‐Shaped Shorting Pin‐Loaded Antennas
Authors: Can Sultan , Kapusuz Kamil Yavuz , Aydin Elif
Published: October 2015

This study presents an artificial neural network (ANN) estimation of the operating frequencies of shorting pin‐loaded rectangular microstrip patch antennas. A feed forward back propagation multilayer perceptron neural network structure is applied in the study. The results are compared with the ones in the literature and the FEM based simulation results. The results of the operating frequencies obtained by using this method are in very good agreement with the experimental results presented in the literature. Several antennas are also simulated by a finite element method based solver and these results are also compared with the results of the proposed neural network model. The average error of the lower frequency obtained by this study has a decrement of 2.025% when compared to the FEM based simulation software and for the upper frequency this difference is 6.835%. The effects of permittivity of the antenna, size of the dimensions of the rectangular patch, and the shorting pin position are also evaluated. In the light of the ANN model and the relations obtained two antennas in the same shape are produced and the results of these antennas are presented as well. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:3025–3028, 2013
Research on Compressive Sensing‐Based 3D Imaging Method Applied to GPR
Authors: Hui‐min Yu , Song Jiang
Published: October 2015

Results in theory of compressive sensing enable the reconstruction of sparse signals from a small set of nonadaptive linear measurements by solving a convex optimization problem. Considering the sparse structure of actual target space in ground penetrating radar (GPR) application, three‐dimensional imaging method based on random aperture compressive sensing (RACS) is brought up, which requires the GPR transceiver to record only a minimum amount of samples through incoherent measurement at each aperture point, and only to measure a small number of random apertures in x‐y plane of interested target space. Simulation and experimental results verified that the proposed RACS method allow much fewer measurement aperture points, and has much sparse imaging results with much higher resolution. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2896–2901, 2013
Synthesis and testing of a p‐H2 hyperpolarized 13C probe based on the pyrazolo[1,5‐a]pyrimidineacetamide DPA‐713, an MRI vector to target the peripheral benzodiazepine receptors
Authors: Cerutti Erika , Viale Alessandra , Damont Annelaure , Dollé Frédéric , Aime Silvio
Published: October 2015

DPA‐713 is the lead compound of a recently developed 2‐phenylpyrazolo[1,5‐a]pyrimidineacetamide series that has been shown to display a good targeting capability toward peripheral benzodiazepine receptors, recently renamed translocator protein (18 kDa) or in short TSPO. On the basis of this structure, a novel derivative bearing a [13C]butynoate moiety has been designed and synthesized (three steps—42% overall yield) providing, upon rapid and quantitative para‐hydrogenation, the corresponding hyperpolarized [13C]alkene. Para‐hydrogen‐induced polarization effects have been detected in both 1H and 13C‐NMR spectra. Upon applying a field cycling procedure, the spin order of para‐H2 added hydrogens is transferred on the 13 C carboxylate moiety yielding a signal enhancement of approximately 4500 times. T1 of the carboxylate carbon atom is approximately 21.9 s (at 9.37 T). A 13 C‐MR image has been acquired by using the 13 C RARE (Rapid Acquisition by Relaxation Enhancement) acquisition protocol on a 10‐mM solution. The main limitation to the in vivo use of this novel para‐hydrogenated [13 C]derivative is its relatively low solubility in aqueous systems. Copyright © 2011 John Wiley & Sons, Ltd.
Synthesis and characterization of an MRI Gd‐based probe designed to target the translocator protein
Authors: Cerutti Erika , Damont Annelaure , Dollé Frédéric , Baroni Simona , Aime Silvio
Published: October 2015

DPA‐713 is the lead compound of a recently reported pyrazolo[1,5‐a]pyrimidineacetamide series, targeting the translocator protein (TSPO 18 kDa), and as such, this structure, as well as closely related derivatives, have been already successfully used as positron emission tomography radioligands. On the basis of the pharmacological core of this ligands series, a new magnetic resonance imaging probe, coded DPA‐C6‐(Gd)DOTAMA was designed and successfully synthesized in six steps and 13% overall yield from DPA‐713. The Gd‐DOTA monoamide cage (DOTA = 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetraacetic acid) represents the magnetic resonance imaging reporter, which is spaced from the phenylpyrazolo[1,5‐a]pyrimidineacetamide moiety (DPA‐713 motif) by a six carbon‐atom chain. DPA‐C6‐(Gd)DOTAMA relaxometric characterization showed the typical behavior of a small‐sized molecule (relaxivity value: 6.02 mM−1 s−1 at 20 MHz). The good hydrophilicity of the metal chelate makes DPA‐C6‐(Gd)DOTAMA soluble in water, affecting thus its biodistribution with respect to the parent lipophilic DPA‐713 molecule. For this reason, it was deemed of interest to load the probe to a large carrier in order to increase its residence lifetime in blood. Whereas DPA‐C6‐(Gd)DOTAMA binds to serum albumin with a low affinity constant, it can be entrapped into liposomes (both in the membrane and in the inner aqueous cavity). The stability of the supramolecular adduct formed by the Gd‐complex and liposomes was assessed by a competition test with albumin. Copyright © 2013 John Wiley & Sons, Ltd.
Conformational analysis of N,N,N‐Trimethyl‐(3,3‐dimethylbutyl)ammonium iodide by NMR spectroscopy: a sterically hindered trans‐standard
Authors: Liu Albert Tianxiang , Nag Mrinmoy , Carroll William R. , Roberts John D.
Published: October 2015

A predominantly trans‐1,2‐disubstituted ethane system – N,N,N‐trimethyl‐(3,3‐dimethylbutyl)ammonium iodide – is of particular interest for conformational analysis, because it contains both an organic and a highly polar substituent, making it soluble and thus applicable to study in a large variety of solvents. The fraction of the trans conformer of this molecule in a wide range of protic and aprotic solvents was determined by the nuclear magnetic resonance proton couplings to be approximately 90%, in contrast to the previously assumed 100%. The consistently strong preference of the trans conformation should establish N,N,N‐trimethyl‐(3,3‐dimethylbutyl)ammonium iodide as a possibly useful ‘trans‐standard’ in conformational analysis, much more so than 1,2‐ditert‐butylethane, which has a poor solubility in many solvents. Copyright © 2013 John Wiley & Sons, Ltd.