bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterisation of quasi‐stationary temperature fields in laser welding by infrared thermography
Authors: Francis J.A. , Gach S. , Olscho S. , Reisgen U. , Haeusler A. , Gillner A. , Poprawe R. 
Published: January 2018

AbstractIn this work, high‐speed thermography is shown to effectively capture quasi‐stationary temperature fields during the laser welding of steel plates. This capability is demonstrated for two cases, with one involving the addition of a ferritic‐bainitic filler wire, and the other involving the addition of a low‐transformation‐temperature (LTT) filler wire. The same welding parameters are used in each case, but the temperature fields differ, with the spacing between isotherms being greater in the case where the low‐transformation‐temperature filler material is added. This observation is consistent with the differences in the extent of the heat‐affected zone in each sample, and the shape of the weld pool ripples on the weld bead surfaces. The characterization of temperature fields in this way can greatly assist in the development of novel methods for reducing residual stresses, such as the application of low‐transformation‐temperature filler materials through partial‐metallurgical injection (PMI). This technique reduces or eliminates tensile residual stresses by controlling the temperature fields so that phase transformations take place at the optimum times, and success can only be guaranteed through precise knowledge of the temperature fields in the vicinity of the welding heat source in real time.
Influence of process strategy on distortion and residual stresses for the powder based laser metal deposition process
Authors: Pirch N. , Schleifenbaum H. , Linnenbrink S. , Gasser A. , Poprawe R. , Niessen M. 
Published: January 2018

AbstractLaser metal deposition (LMD) induces a complex 3‐axis residual stress state, which superimposes the external service stresses and can cause unpredicted in‐service failures. To optimize the process it is important to know the mechanisms and the opportunities to influence the occurrence of residual stresses. From the mathematical point of view, laser metal deposition represents a free boundary value problem. The track geometry is part of the solution. Previously the authors developed a thermal model that is used to calculate the time‐ and space resolved temperature distribution and the track geometry. The thermal model encompasses the powder stream, its interaction with the laser radiation, the shadowing of the laser radiation by the particles, the heating of the particles and the melt pool computation. In this publication, the evolution of residual stresses for overlapping tracks for single and multilayer processing for different powder mass rates is described.
Dietary Factors Modulate Colonic Tumorigenesis Through the Interaction of Gut Microbiota and Host Chloride Channels
Authors: Zhang Yong , Kang Chao , Wang Xiao‐lan , Zhou Min , Chen Meng‐ting , Zhu Xiao‐hui , Liu Kai , Wang Bin , Zhang Qian‐yong , Zhu Jun‐dong , Mi Man‐tian 
Published: January 2018

ScopeIn recent decades, the association among diet, gut microbiota, and the risk of colorectal cancer (CRC) has been established. Gut microbiota and associated metabolites, such as bile acids and butyrate, are now known to play a key role in CRC development. The aim of this study is to identify that the progression to CRC is influenced by cholic acid, sodium butyrate, a high‐fat diet, or different dose of dihydromyricetin (DMY) interacted with gut microbiota.Methods and resultsAn AOM/DSS (azoxymethan/dextran sodium sulfate) model is established to study the gut microbiota compsition before and after tumor formation during colitis‐induced tumorigenesis. All above dietary factors profoundly influence the composition of gut microbiota and host colonic tumorigenesis. In addition, mice with DMY‐modified initial microbiota display different degrees of chemically induced tumorigenesis. Mechanism analysis reveals that gut microbiota‐associated chloride channels participated in colon tumorigenesis.ConclusionGut microbiota changes occur in the hyperproliferative stage before tumor formation. Gut microbiota and host chloride channels, both of which are regulated by dietary factors, are associated with CRC development.
Ultrawideband dipole receiving antenna for measuring short pulses with extended bandwidth
Authors: Balzovsky Evgeny , Buyanov Yury , Koshelev Vladimir , Nekrasov Eduard 
Published: January 2018

AbstractThis article presents the design of an ultrawideband active integrated antenna based on an electric dipole and the results of its testing. The antenna is intended to perform low‐distortion measurements of the instantaneous electric field strength of short pulses whose spectra lie within the frequency range from 0.05 to 3 GHz. The antenna is fabricated using the technology of printed circuit boards on a 1‐mm thick FR4 plate of dimensions 60 × 28 mm. It has a built‐in balancing‐to‐unbalancing unit and an unbalanced output. The difference in output voltage pulse waveform between the proposed antenna and a reference TEM‐antenna is insignificant.
Low‐profile tilted‐beam waveguide slot antenna using corrugations for UAV applications
Authors: Jin Yunnan , Lee Hojoo , Woo Daewoong , Choi Jaehoon 
Published: January 2018

AbstractWe propose a low‐profile tilted‐beam waveguide slot antenna using corrugations for unmanned aerial vehicle (UAV) applications. The proposed antenna consists of a WR‐90 rectangular waveguide with a central slot on top and two asymmetric corrugations. The antenna satisfies a 10‐dB return loss from 9.82 to 10.18 GHz. To realize the low‐profile characteristic, the proposed antenna is fed from the flank instead of the bottom of the waveguide. In addition, the proposed antenna attains a tilted beam pointing 45 degrees from the broadside direction due to the asymmetric corrugations on the conducting plate. The antenna has a measured peak gain of 6.95 dBi at the center frequency of the operation band, which satisfies the gain requirement for UAV applications. The experimental and simulated results of the proposed antenna are in good agreement.
A compact four‐element MIMO antenna for WLAN applications
Authors: Pandit Soumen , Mohan Akhilesh , Ray Priyadip 
Published: January 2018

AbstractThis article presents a compact four‐element multiple‐input multiple‐output (MIMO) antenna for wireless local area network applications. The overall volume of the proposed MIMO antenna is 26 mm × 26 mm × 0.8 mm and the edge‐to‐edge distance is 4 mm. The MIMO antenna operates at 5.6 to 5.8 GHz frequency band with isolation greater than 15.4 dB. The envelope correlation coefficient and the channel capacity loss for the proposed MIMO antenna are within the acceptable limits in the operating frequency band. The simulated results are verified with fabrication and measurements.
Linear CMOS power amplifier using continuous gate voltage control
Authors: Kim Joonhyung 
Published: January 2018

AbstractIn this article, an linearization technique using a gate voltage adaptation of a common gate stage for a cascode CMOS power amplifier (PA) is presented. The tracking of minimum in‐band third‐order intermodulation distortion by controlling with respect to instantaneous power level enhances the linearity of CMOS PA over a wide range of operation level. The experimental results show that the CMOS PA with proposed scheme has an overall efficiency of 34.6% and a gain of 25.8 dB at an average output power of 27 dBm. Under this condition, the adjacent channel leakage ratio is <–34.8 and 5.4 dBc lower when compared with the use of no linearization technique.
A novel two‐step flare wide band horn antenna
Authors: Manshari Saeed , Kashani Farokh , Moradi Gholamreza , Sarijlo Mohamad 
Published: January 2018

AbstractIn this letter, a novel dual section or two step flare horn antenna for working at 1.5–8 GHz is presented. Novelty of this design is through utilizing of double flare section in horn so that the adverse effects of diffractions caused by ridges on radiation are decreased. The proficiency of new design is indicated in terms of location of the phase center, radiation pattern, and VSWR. Similarity of pattern for the two main polarizations over 10 dB beamwidth at 45° slant rotation is a feature of this antenna for applications that need similar amplitude patterns for two horizontal and vertical polarizations in the main beam. One prototype of antenna has been fabricated and tested with excellent agreement between measured and simulated results. Amplitude radiation patterns of this antenna for vertical and horizontal polarizations and also distance of the phase center from aperture versus frequency are illustrated.
4 × 4 MIMO antenna design with folded ground plane for 2.4 GHz WLAN applications
Authors: Ahmad Muhammad Sajjad , Mohyuddin Wahab , Choi Hyun Chul , Kim Kang Wook 
Published: January 2018

AbstractA 4 × 4 MIMO antenna design for packed conditions is presented for WLAN applications. The proposed antenna consists of a radiating patch, a parasitic patch, and a folded ground plane to achieve the desired resonant frequency, return loss, bandwidth, and isolation for the worst case scenario. The antennas are fed individually by 50 Ohm coaxial feedings. The proposed antenna design has measured 73 MHz bandwidth >10 dB, and exhibits isolation better than 10 dB over the desired band, when there is no physical separation between antennas. The prototype for the 4 × 4 MIMO is constructed and the results are compared. The simulation and measurement results are well in agreement.
Study and design of wristband RFID antenna for healthcare applications
Authors: Marouf F. Z. , Ziani Kerarti D. 
Published: January 2018

AbstractThe RFID technology is widely improved in the last decade. It offers different applications touching different areas. Tags could be modeled under several shapes serving the desired application; it can take a wristband form in the case of human body identification. In this paper, we present a design of an antenna implemented on the tag, with the aim to sense different physiological human parameters (temperature, blood pressure, O2 saturation, etc.). This antenna has a bent form, suitable for the medical application. It was put on flexible substrate to be conformal to the wrist. It presents good characteristics in terms of impedance matching.
Study on the estimation of the LED‐package life using a statistical approach
Authors: Park Seil , Kim Gun So , Kim Chung Hyeok 
Published: January 2018

AbstractSince the LED has been popularly used in the lighting field, many of the standards for LED lights such as those regarding LED modules, LED luminaries, and LED lamps have been renewed or newly published. In the development of the relevant standards, many other standards for LED appurtenances have also been developed to measure the LED packages and to produce the luminous flux, color chromaticity, color rendering index, and luminous‐intensity distribution. Although many standards has been developed for different purposes, a standard for the projection of the lumen maintenance of the LED packages and luminaires is nonexistent. LED products are widely known for their long lifetimes, but the formation of accurate definitions of their life periods and the lumen maintenance regarding the LED products are not possible due to the LED‐package components such as the phosper material and the soldering techniques. The method in the IES LM‐80‐08 had been mainly used as an alternative for the projection of the lumen maintenance, but an active discussion of the Border Function and Temperature Acceleration methods in terms of their use as current international standards has occurred. In this study, a new equation for the lumen‐maintenance projection is proposed for the accurate measurement of the lumen maintenance for which a set of 12 LED packages is used. By using the equation, the real value of the LED‐product life can be easily estimated, and it can be compared with the manufacturer claim regarding the value of the LED‐product life.
Mitigation of common mode noise in bent differential transmission line using curved PBG unit cell
Authors: Ranade S. R. , Shevgaonkar R. K. , Sidhique A. , Rao P. H. 
Published: January 2018

AbstractA curved photonic band gap (PBG) unit cell loaded bent differential line is proposed to suppress the differential‐to‐common mode conversion noise. The PBG unit cell, loaded at the bend is designed and optimized to provide the required delay characteristic on the inner transmission line of a differential line. An LC equivalent circuit of curved PBG unit cell is proposed and constituent lumped element parameters are calculated. The realized PBG loaded bent differential line exhibits a measured mode conversion noise below −20 dB from DC to 6 GHz demonstrating a common mode noise suppression of around 9 dB.
Conceptual design and implementation of a four‐element MIMO antenna system packaged within a metallic handset
Authors: Gao Chen , Li Xiao‐Qian , Lu Wen‐Jun , Wong Kin‐Lu 
Published: January 2018

AbstractThe conceptual design of a multiple input multiple output (MIMO) antenna system packaged within a metallic handset for future wireless communications is proposed, simulated, and implemented. The presented MIMO antenna system is composed of four‐identical slotted microstrip magnetic dipoles. The whole antenna system is installed within an emulated handset with a metallic back cavity and frames. A few antenna prototypes are fabricated and measured to validate the conceptual design. Owning to the inherent microstrip magnetic dipole configuration, the packaged MIMO antenna system exhibits a good impedance matching, a high element isolation, an acceptable average radiation efficiency of about 40%, and a wide beam coverage performance at 3.5 GHz‐band. Compared to conventional single input single output (SISO) wireless communication systems, the channel capacity can be nearly tripled by employing the designed MIMO handset.
Optically transparent microstripline with micro‐ and wired‐metal mesh
Authors: Lee Hoon Hee , Kang Seok Hyon , Jung Chang Won 
Published: January 2018

AbstractOptically transparent microstriplines designed using a conductive micro‐metal mesh film (µ‐MMF) and a conductive wired‐metal mesh (WMM) are presented. The transparent microstriplines are fabricated on a transparent acryl substrate with thickness (hs) of 1.25 mm, relative permittivity (ɛr) of 2.6, and loss tangent (tan δ) of 0.009. The average optical transmittance of µ‐MMF and WMM is 62% and 71%, respectively, in the visible band (400–750 nm). The sheet resistance of µ‐MMF and WMM is 0.08 and 0.01 Ω/sq, respectively. In addition, two types of copper microstriplines are fabricated for performance comparison. Insertion losses (S21) and return losses (S11) of transparent microstriplines of lengths 1, 3, and 5 cm are measured to be under 2 dB and higher than 15 dB up to 6 GHz, respectively.
Multiband reconfigurable Bowtie slot antenna using switchable slot extensions for WiFi, WiMAX, and WLAN applications
Authors: Mansoul Ali , Seddiki Mohamed Lamine 
Published: January 2018

AbstractIn this letter, a compact multi‐band reconfigurable CPW fed bowtie slot antenna is presented and these performances are discussed. The known properties of the bowtie antenna, namely a high gain and a fairly large bandwidth have been used in order to design a reconfigurable multiband antenna which makes it possible to switch between a single band (initial mode) and dual band or triple band modes, making it more agile in frequency. The proposed approach is based on the integration of two pairs of slots on the two sides of the antenna to create new bands optimized to operate in the two bands of WiFi and WiMAX at 2.4 GHz and 3.5 GHz, respectively. The results of measurements and simulations are presented and compared and a good agreement is established. The antenna is intended for multiservices and cognitive radios applications.
An efficient and reliable small signal intrinsic parameters extraction for HEMT GaN devices
Authors: Maafri Djabar , Saadi Abdelhalim , Slimane Abdelhalim , Yagoub Mustapha C. E 
Published: January 2018

AbstractTo efficiently design GaN HEMT devices, a robust extraction of their intrinsic electrical equivalent circuit element values is critical. Aiming to accurately determine all intrinsic element values, a new elements‐based small‐signal equivalent circuit technique is introduced in this paper. Compared to the conventional GaAs‐based HEMT small‐signal model composed of 16 elements, the proposed equivalent circuit consists of two parasitic distributed interelectrode extrinsic capacitances and two additional feedback intrinsic resistances. The circuit element values were obtained starting from measured S‐parameters and using Y‐matrix transformations. The efficiency of the proposed methodology was demonstrated through excellent agreement between simulated and measured data up to 60 GHz.
A ku‐band distributed SPDT switch in 0.5 μm AlGaN/GaN HEMT technology
Authors: Zaibet Imane , Hettak Khelifa , Yagoub Mustapha C. E. 
Published: January 2018

AbstractIn this paper, a wideband single‐pole double‐throw (SPDT) switch using the traveling‐wave concept was demonstrated. Realized in 0.5 μm AlGaN/GaN HEMT process, it achieves good performance at Ku‐band despite the process being intended for low‐frequency applications. This type of switch combined the off‐state shunt transistors and series coplanar waveguide (CPW) lines to form an artificial transmission line. CPW is also used to eliminate parasitics associated with through‐substrate microstrip vias and coupling of adjacent transmission lines. An accurate switch HEMT model was extracted and used in the design. A 9–25 GHz single‐pole double‐throw (SPDT) switch in conjunction with quarter‐wavelength impedance transformers demonstrates an insertion loss of less than 6 dB, return loss better than 10 dB and an isolation of better than 25 dB.
A novel ultra‐wideband antipodal Vivaldi antenna with trapezoidal dielectric substrate
Authors: Wan Fayu , Chen Jun , Li Binhong 
Published: January 2018

AbstractAn ultra‐wideband Vivaldi antenna is designed in this article, its frequency band is 3.3–40 GHz. Based on the traditional antipodal Vivaldi antenna, a trapezoidal dielectric substrate is loaded in the direction of major axis, which not only eliminates the antenna gain peak shifting problem, but also improves the directional radiation performance. The dimension of the antenna is 57.5 mm × 60.7 mm. The substrate of the antenna is Rogers RO4003C with relative dielectric constant (ɛr) of 3.38, loss tangent of 0.0027, and thickness of 0.508 mm. The simulation and measured results show that bandwidth of the antenna is 3.3–40 GHz, and it also has many advantages such as good radiation direction, high gain, narrow main lobe width, and low cross‐polarization ratio.
High isolation 4‐port diplexer based on double‐sided parallel‐strip lines
Authors: Lu Yun‐Long , Wang Yi , Hua Changzhou , Liu Taijun 
Published: January 2018

AbstractA high isolation 4‐port diplexer implemented using double‐sided parallel‐strip lines (DSPSLs) is presented in this letter. Two back‐to‐back 3‐port diplexers and a 180° phase shifter are employed to construct the proposed device. The DSPSL structure enables a compact phase shifter without incurring any extra circuit footprint. The 4‐port circuit topology suppresses the leakage between the 2 channels by signal cancellation, resulting in significantly improved channel isolation. For demonstration, a 4‐port diplexer with operating frequencies of 1.85 and 2.1 GHz is designed, fabricated and measured. The experimental results show that the 4‐port diplexer has good in‐band performance and high isolation of 50 and 51 dB. This is an improvement of over 23 dB compared with the conventional 3‐port diplexer.
Filtering Gysel power divider with arbitrary power splitting ratio
Authors: Dong Gaoya , Wang Weimin , Zhang Bo , Liu Yuanan 
Published: January 2018

AbstractA novel filtering Gysel power divider (PD) structure based on coupled lines is presented to realize arbitrary power splitting ratio and filtering response. The proposed filtering PD consists of three parallel‐coupled lines, two short‐circuited stubs, two stepped impedance stubs and two grounded isolation resistors. Two transmission zeros (TZs) are introduced by the stepped impedance stubs, which can greatly improve the passband selectivity and out‐of‐band rejection performances. Theoretically, closed‐form equations for the proposed structure are derived based on even‐odd mode method. For verification, two filtering Gysel PDs with equal and unequal power splitting ratios (
) are designed and experimentally demonstrated in this paper.
Asymmetric double QW superluminescent diodes for broadband and high‐power use
Authors: Kwon Oh‐Kee , Lee Chul Wook 
Published: January 2018

AbstractWe report the use of broadband and high‐power InGaAs/GaAs asymmetric double quantum‐well (ADQW) superluminescent diodes (SLDs), which consist of a tilted, bent, and straight waveguide. To examine the effects of the arrangement of the ADQW and the gain provided by a straight waveguide on the output performances, we fabricated SLDs with different lengths for two types of ADQW, that is, a wide QW at the p‐side for Sample 1, and a narrow QW at the p‐side for Sample 2, and tested their spectral width and output power. The fabricated SLDs with a straight length (L3) of 80 μm show −3 dB spectral widths of 122 and 116 nm and output powers of 20 and 16 mW at an injection current of 250 mA for Samples 1 and 2, respectively. For both samples, it appears that, as the L3 increases, the spectral width decreases and the output power increases. From this result, we confirmed that both the spectral width and the output power can be adjusted and optimized at a given structure for various applications.
RF phase noise filtering properties of an actively mode‐locked laser
Authors: Mbonde Hamidu , Ozharar Sarper , Ozdur Ibrahim 
Published: January 2018

AbstractIn this article, we are presenting the experimental results and theoretical analysis of radio frequency (RF) phase noise filtering properties of a high Q cavity actively driven mode‐locked laser. The experimental results show that, the phase noise of a 10 GHz RF tone can be filtered by at least 10 dB at 200 kHz offset frequency. A theoretical analysis on the limits of phase noise filtering due to the spontaneous emission and the frequency mismatch between the laser cavity modes and the synthesizer frequency is also included.
Reconfigurable and stable frequency selective surfaces on nonuniform and finite arrays
Authors: Silva Neto V. P. , D'Assunção A. G. 
Published: January 2018

AbstractA reconfigurable frequency selective surface (FSS) is presented based on a nonuniform and finite array of square loop conducting patches printed on a dielectric substrate. The reconfigurability is performed changing the polarization of PIN diodes in the patch elements of the FSS array, from OFF to ON state and vice versa. Simulation is performed by the wave concept iterative procedure (WCIP) formulation and Ansoft HFSS package. Remarkably, a generalization of the WCIP method is proposed to solve scattering problems on FSS structures composed of nonuniform and finite arrays. Prototypes are fabricated for comparison purpose. Simulations and measurements show that the nonuniform and finite FSS has dual band behavior and stable frequency response for different angles of the incident plane wave. A very good agreement between HFSS simulation, WCIP formulation, and experimental results is verified.