bluuebunny/crossref_metadata_2025 huggingface dataset:
Palmprint gender classification by convolutional neural network
Authors: Xie Zhihuai , Guo Zhenhua , Qian Chengshan
Published: January 2018

Palmprint gender classification can revolutionise the performance of authentication systems, reduce searching space and speed up matching rate. However, to the best of their knowledge, there is no literature addressing this issue. The authors design a new convolutional neural network (CNN) structure, fine‐tuning Visual Geometry Group Network, up to 19 layers to achieve a 20‐layer network, for palmprint gender classification. Experimental results show that the proposed structure could achieve good performance for gender classification. They also investigate palmprint images with 15 different kinds of spectra. They empirically find that a palmprint image acquired by the Blue spectrum could achieve 89.2% correct classification and could be considered as a suitable spectrum for gender classification. The neural network is able to classify a 224 × 224 × 3‐pixel palmprint image in <23 ms, verifying that the proposed CNN is an effective real‐time solution.
Low‐noise design of fault‐tolerant flux‐switching permanent‐magnet machines
Authors: Mao Yanxin , Liu Guohai , Zhao Wenxiang , Ji Jinghua , Wang Zheng
Published: January 2018

The high variable flux density in the air‐gap of fault‐tolerant flux‐switching permanent‐magnet (FT‐FSPM) machine results in rich harmonics of the magnetic field, thus generating large vibration and noise. This study proposes two novel FT‐FSPM machines which can effectively reduce the radial pressure, thus reducing the vibration and noise. First, the radial pressure of the initial FT‐FSPM machine is analysed. Second, the novel proposed FT‐FSPM machines are introduced and analysed. Third, the electromagnetic performance, including back electromotive force, output torque, inductance, and radial pressure harmonics, of the initial and the two proposed machines are compared by finite element method. Then, the vibration modes with corresponding natural frequencies are predicted. The vibration and noise are simulated by boundary element method. Finally, the effectiveness of the low‐noise design is verified by measurement results.
High power density multiple output permanent magnet alternator
Authors: Mudhigollam Uday Kumar , Choudhury Umakanta , Hatua Kamalesh
Published: January 2018

The power electronic equipment is very much required when the alternator, capable of providing certain voltage level with a certain frequency, has to supply power to the load that needs voltage level or frequency other than the rated voltage and rated frequency of the alternator. At the same time, the power electronic circuit will also become complex if the alternator is to be provided with multiple outputs of different voltages with different frequencies. Therefore, a hybrid flux permanent magnet alternator (PMA) with multiple outputs is proposed in this study by utilising both radial flux permanent magnet (PM) technology and axial flux PM technology. The utilisation of both radial and axial flux PM technologies in the proposed hybrid flux multiple output PMA increases the power density also compared with that of conventional multiple output PMA. A comparison study is carried out between the conventional PMA and proposed hybrid flux multiple output PMA for the same volume and the same is also validated with finite‐element method software and prototype testing.
Integrated GSM‐UWB Fibonacci‐type antennas with single, dual, and triple notched bands
Authors: Srivastava Kunal , Kumar Ashwani , Kanaujia Binod K. , Dwari Santanu , Verma Anand Kumar , Esselle Karu P. , Mittra Raj
Published: January 2018

This study presents four integrated Fibonacci‐type Global System for Mobile (GSM) ultra‐wideband (UWB) antennas with single, dual, and triple band‐notched characteristics. These antennas have been designed to control potential interference in Wi‐Max and WLAN bands. The antenna operates in the 900 MHz GSM band and also in the 3.2–11.9 GHz extended UWB band. The 900 MHz operating band can be further tuned to get the antenna to operate in a specific GSM band. Triple notches have been created at frequencies within several bands, such as 3.4 GHz Wi‐Max (3.06–3.54 GHz), 4.23 GHz WLAN (3.59–4.86 GHz), and 6.35 GHz (5.93–7.15 GHz) with voltage standing wave ratio (VSWR) levels of 7.9, 11.3, and 7, respectively. These notch bands are also tuneable to some extent. The measured gain varies from −1.92 to 10.2 dBi. Measured radiation patterns of the antenna are also presented to validate its performance. The integrated antenna has a radiation efficiency in the range of 78–98% in the UWB and 98% in the GSM band. The fidelity factor in time domain varies between 0.76 and 0.84, depending on the orientation of the antenna. This research confirms that the Fibonacci monopole can be used as a multiband antenna in GSM and UWB bands.
Design of an inductive pickup type displacement transducer using an electro‐optic effect of lithium‐niobate‐based Mach–Zehnder interferometers
Authors: Mondal Bikas , Kumar Brajesh , Mandal Nirupama
Published: January 2018

In this study, an improved inductive pickup coil and an electro‐optic type displacement transmitter has been proposed. A modified differential inductance bridge network has been used to generate electrical signals and Mach–Zehnder interferometer (MZI) converts an electrical signal into an optical signal. The sensitivity of the sensor part of the transducer is very good because of two parallel magnetic paths for the inductive pickup. The theoretical equations explaining the operation of the transducer are derived. The proposed transducer is tested experimentally to obtain the static characteristics. The characteristics of the MZI‐based displacement transmitter have been observed by using PC‐based Opt wave Opti‐BPM.v.9 simulation software in the linear zone. The experimental and simulated results are reported in this study. Very good linear characteristics of the transducer with adjustable sensitivity have been observed. The transmitter output in the form of normalised intensity of light is also found to be linearly related with displacement. The theoretical equations derived in this are found to support the experimental characteristics to a very good extent.
Intelligent prediction of transformer faults and severities based on dissolved gas analysis integrated with thermodynamics theory
Authors: Ghoneim Sherif S.M.
Published: January 2018

Most presented dissolved gas analysis (DGA) techniques were interested in determining the fault types (FTs), but few articles discussed the corresponding severity of these faults. Here, the thermodynamic theory is utilised to evaluate the fault severity based on the energy associated with each FT. Therefore, energy weighted DGA is proposed, where the individual gas concentration is multiplied by a relative factor that relates to the enthalpy change of reaction. A fuzzy logic system is built based on the IEC code rules, the transformer condition code that is reported in IEEE Standard C57.104‐2008, and the thermodynamic theory. For enhancing the network fault diagnosis of the power transformers all over the distribution network, the proposed fuzzy logic approach is employed for its integration in accordance with the distributed agents of the distribution substations. This smart system facilitates evaluating decisions of the distributed agents as well as providing a higher decision level if needed. That is achieved by sending the important information about transformers attained by the proposed fuzzy approach such as the FT, its severity, the total dissolved combustion gases condition, the recommended action, in addition to the period of incoming action to the primary substation.
The ESO’s VLT type Ia supernova spectral set of the final two years of SNLS
Authors: Balland C. , Cellier-Holzem F. , Lidman C. , Astier P. , Betoule M. , Carlberg R. G. , Conley A. , Ellis R. S. , Guy J. , Hardin D. , Hook I. M. , Howell D. A. , Pain R. , Pritchet C. J. , Regnault N. , Sullivan M. , Arsenijevic V. , Baumont S. , El-Hage P. , Fabbro S. , Fouchez D. , Mitra A. , Möller A. , Mourão A. M. , Neveu J. , Roman M. , Ruhlmann-Kleider V.
Published: January 2018

Aims. We aim to present 70 spectra of 68 new high-redshift type Ia supernovae (SNe Ia) measured at ESO’s VLT during the final two years of operation (2006–2008) of the Supernova Legacy Survey (SNLS). This new sample complements the VLT three year spectral set. Altogether, these two data sets form the five year sample of SNLS SN Ia spectra measured at the VLT on which the final SNLS cosmological analysis will partly be based. In the redshift range considered, this sample is unique in terms of homogeneity and number of spectra. We use it to investigate the possibility of a spectral evolution of SNe Ia populations with redshift as well as SNe Ia spectral properties as a function of lightcurve fit parameters and the mass of the host-galaxy.

Methods. Reduction and extraction are based on both IRAF standard tasks and our own reduction pipeline. Redshifts are estimated from host-galaxy lines whenever possible or alternatively from supernova features. We used the spectro-photometric SN Ia model SALT2 combined with a set of galaxy templates that model the host-galaxy contamination to assess the type Ia nature of the candidates.

Results. We identify 68 new SNe Ia with redshift ranging from z = 0.207 to z = 0.98 for an average redshift of z = 0.62. Each spectrum is presented individually along with its best-fit SALT2 model. Adding this new sample to the three year VLT sample of SNLS, the final dataset contains 209 spectra corresponding to 192 SNe Ia identified at the VLT. We also publish the redshifts of other candidates (host galaxies or other transients) whose spectra were obtained at the same time as the spectra of live SNe Ia. This list provides a new redshift catalog useful for upcoming galaxy surveys. Using the full VLT SNe Ia sample, we build composite spectra around maximum light with cuts in color, the lightcurve shape parameter (“stretch”), host-galaxy mass and redshift. We find that high-z SNe Ia are bluer, brighter and have weaker intermediate mass element absorption lines than their low-z counterparts at a level consistent with what is expected from selection effects. We also find a flux excess in the range [3000–3400] Å for SNe Ia in low mass host-galaxies (M < 1010M⊙) or with locally blue U–V colors, and suggest that the UV flux (or local color) may be used in future cosmological studies as a third standardization parameter in addition to stretch and color.
Exploring the 13CO/C18O abundance ratio towards Galactic young stellar objects and HII regions
Authors: Areal M. B. , Paron S. , Celis Peña M. , Ortega M. E.
Published: January 2018

Aims. Determining molecular abundance ratios is important not only for the study of Galactic chemistry, but also because they are useful to estimate physical parameters in a large variety of interstellar medium environments. One of the most important molecules for tracing the molecular gas in the interstellar medium is CO, and the 13CO/C18O abundance ratio is usually used to estimate molecular masses and densities of regions with moderate to high densities. Nowadays isotope ratios are in general indirectly derived from elemental abundances ratios. We present the first 13CO/C18O abundance ratio study performed from CO isotope observations towards a large sample of Galactic sources of different natures at different locations.

Methods. To study the 13CO/C18O abundance ratio, we used 12CO J = 3 − 2 data obtained from the CO High-Resolution Survey, 13CO and C18O J = 3 − 2 data from the 13CO/C18O (J = 3 − 2) Heterodyne Inner Milky Way Plane Survey, and some complementary data extracted from the James Clerk Maxwell Telescope database. We analyzed a sample of 198 sources composed of young stellar objects (YSOs), and HII and diffuse HII regions as catalogued in the Red MSX Source Survey in 27.°5 ≤ l ≤ 46.°5 and |b|0.°5.

Results. Most of the analyzed sources are located in the galactocentric distance range 4.0–6.5 kpc. We found that YSOs have, on average, lower 13CO/C18O abundance ratios than HII and diffuse HII regions. Taking into account that the gas associated with YSOs should be less affected by the radiation than in the case of the others sources, selective far-UV photodissociation of C18O is confirmed. The 13CO/C18O abundance ratios obtained in this work are systematically lower than those predicted from the known elemental abundance relations. These results will be useful in future studies of molecular gas related to YSOs and HII regions based on the observation of these isotopes.
Rotational broadening and conservation of angular momentum in post-extreme horizontal branch stars
Authors: Fontaine G. , Latour M.
Published: January 2018

We show that the recent realization that isolated post-extreme horizontal branch (post-EHB) stars are generally characterized by rotational broadening with values of V rot sini between 25 and 30 km s−1 can be explained as a natural consequence of the conservation of angular momentum from the previous He-core burning phase on the EHB. The progenitors of these evolved objects, the EHB stars, are known to be slow rotators with an average value of V rot sini of ~7.7 km s−1. This implies significant spin-up between the EHB and post-EHB phases. Using representative evolutionary models of hot subdwarf stars, we demonstrate that angular momentum conservation in uniformly rotating structures (rigid-body rotation) boosts that value of the projected equatorial rotation speed by a factor ~3.6 by the time the model has reached the region of the surface gravity-effective temperature plane where the newly-studied post-EHB objects are found. This is exactly what is needed to account for their observed atmospheric broadening. We note that the decrease of the moment of inertia causing the spin-up is mostly due to the redistribution of matter that produces more centrally-condensed structures in the post-EHB phase of evolution, not to the decrease of the radius per se.
Weinreb β-Ketoamides in Enantioselective Organocatalysis: A Balance between Reactivity and Selectivity
Authors: Bugaut Xavier , Du Haiying , Dudognon Yohan , Rodriguez Jean , Constantieux Thierry
Published: January 2018

β-Dicarbonyl compounds have established themselves as substrates of choice in enantioselective organocatalysis because of their easy activation. Among them, β-diketones, β-diesters, and β-ketoesters lead the dance and there has been only limited work with other β-dicarbonyl compounds as pronucleophiles. In this Synpacts article, we wish to discuss our recent contributions to the introduction of Weinreb β-ketoamides in organocatalyzed transformations, where they can provide an interesting balance between reactivity and selectivity, with also interesting potentialities in terms of postfunctionalization.

1 Introduction

2 Preparation of Weinreb β-Ketoamides

3 Michael Addition to Nitroolefins

4 Multicomponent Synthesis of Tetrahydropyridines

5 Outlook
Predictive Value of a Persistent Tachycardia to Indicate Impending Perforation in Necrotizing Enterocolitis
Authors: Becker Jan , van der Schyff Francisca
Published: January 2018

Introduction Necrotizing enterocolitis (NEC) is a devastating disease of infancy. Full-thickness bowel wall necrosis may lead to perforation, peritonitis, and death. Timeous clinical diagnosis of impending perforation is imperative.

Objective The objective of this study was to determine whether a persistent tachycardia in an infant with proven NEC is indicative of full-thickness bowel wall necrosis and therefore impending perforation.

Study Design This study was conducted at the University of Pretoria academic hospitals. Forty-five neonates with proven NEC were divided into a surgical group (32 progressed to full-thickness bowel necrosis) and a nonsurgical group (13 resolved on conservative treatment). Differences in the pulse rate between the groups were analyzed.

Results The 24-hour leading average pulse rate data for the surgical group were analyzed over a period of 10 days leading up to surgery and compared with the nonsurgical group. A clear upward trend of the mean pulse rate was observed in the surgical group, 48 hours prior to surgery. This was statistically significant (p < 0.05).

Conclusion This study demonstrated that a persistent tachycardia in a neonate with NEC is a predictor of progression to full-thickness bowel wall necrosis. Pulse rate is therefore an important clinical tool when deciding on operative management in NEC.
Have the Annual Trends of Total Knee Arthroplasty in Rheumatoid Arthritis Patients Changed?
Authors: Harb Matthew , Solow Max , Newman Jared , Sodhi Nipun , Pivec Robert , George Jaiben , Sultan Assem , Khlopas Anton , Shah Neil , Roche Martin , Mont Michael
Published: January 2018

As the use of disease modifying antirheumatic drugs have increased, it remains unclear whether or not this has affected the rates of total knee arthroplasty (TKA) in rheumatoid arthritis (RA) patients. Therefore, the purpose of this study was to evaluate the annual trends of RA patients who underwent TKA. Specifically, we evaluated: (1) the annual trends of TKAs due to RA in the United States population; and (2) the annual trends in the proportion of TKAs due to RA in the United States. The Nationwide Inpatient Sample was used to identify all patients who underwent TKA between 2002 and 2013 (n = 6,492,873). Then, we identified TKA patients who had a diagnosis of RA, defined by the International Classification of Diseases, Ninth Revision (ICD-9) code 714.0. The incidence of TKAs with a diagnosis of RA in the United States was calculated using the U.S. population as the denominator. Regression models were used to analyze the annual trends of RA in patients who underwent TKA. A total of 209,332 RA patients were identified who underwent TKA. The annual prevalence of RA in patients who underwent TKA slightly increased, from 33.2 per 1,000 TKAs in 2002 to 35 per 1,000 TKAs in 2013 (R
2 = 0.254, p = 0.095). The annual number of TKAs with a diagnosis of RA increased by 93.1% from 11,618 to 22,430. After normalizing for the U.S. population, the incidence of TKAs with RA increased from 5.4 to 9.2 TKAs per 1 million U.S. adults (incidence rate ratio [IRR] = 1.05; 95% confidence interval [CI], 1.05–1.05; p < 0.001). In 2002, 11,618 (3.31%) TKAs, and in 2013, 22,430 (3.50%) TKAs were due to RA. The prevalence of RA in those who underwent TKA remained the same from 2002 to 2013 (coefficient = 0.02; 95% CI, –0.01 to 0.05; p = 0.095). The results of this study demonstrated that the rates of TKA performed in RA patients have remained relatively stable. Furthermore, there may have been a decline in the rate of RA patients undergoing TKA, due to an increase in the U.S. population by approximately 28.8 million during the study period.
A Double-Blind, Randomized, Placebo-Controlled Trial of 17 Alpha-hydroxyprogesterone Caproate in the Management of Preterm Premature Rupture of Membranes
Authors: Sit Anita , Sherwin Katie , Lyell Deirdre , Blumenfeld Yair , El-Sayed Yasser , Langen Elizabeth
Published: January 2018

Objective The objective of this study was to evaluate whether weekly administration of 17 α-hydroxyprogesterone caproate (17-OHPC) increases the number of women who achieve 34 weeks of gestation after preterm premature rupture of membranes (PPROM).

Study Design We conducted a multicenter double-blind, randomized controlled trial of 17-OHPC versus placebo among women with PPROM. Women with singleton pregnancy, clinically confirmed PPROM, and without evidence of active infection or major fetal malformation between 240/7 and 320/7 weeks of pregnancy were offered enrollment. Women received weekly injections of 17-OHPC versus placebo until 340/7 weeks of gestation or delivery. The remainder of care was per hospital protocol. The primary outcome was achievement of 34 weeks of gestation. Secondary outcomes included length of latency and maternal and fetal outcomes.

Results In this study, 21 women were enrolled. Eleven women received placebo and 10 received 17-OHPC. The study was closed prematurely secondary to poor enrollment. None of the women remained pregnant until 34 weeks of gestation. The median latency periods were 8 and 14.5 days for the placebo and 17-OHPC groups, respectively (p = 0.14). There were no differences in maternal or neonatal outcomes.

Conclusion We did not identify any benefit from administration of 17-OHPC in pregnancies complicated by PPROM.
Grid-converged solution and analysis of the unsteady viscous flow in a two-dimensional shock tube
Authors: Zhou Guangzhao , Xu Kun , Liu Feng
Published: January 2018

The flow in a shock tube is extremely complex with dynamic multi-scale structures of sharp fronts, flow separation, and vortices due to the interaction of the shock wave, the contact surface, and the boundary layer over the side wall of the tube. Prediction and understanding of the complex fluid dynamics are of theoretical and practical importance. It is also an extremely challenging problem for numerical simulation, especially at relatively high Reynolds numbers. Daru and Tenaud [“Evaluation of TVD high resolution schemes for unsteady viscous shocked flows,” Comput. Fluids 30, 89–113 (2001)] proposed a two-dimensional model problem as a numerical test case for high-resolution schemes to simulate the flow field in a square closed shock tube. Though many researchers attempted this problem using a variety of computational methods, there is not yet an agreed-upon grid-converged solution of the problem at the Reynolds number of 1000. This paper presents a rigorous grid-convergence study and the resulting grid-converged solutions for this problem by using a newly developed, efficient, and high-order gas-kinetic scheme. Critical data extracted from the converged solutions are documented as benchmark data. The complex fluid dynamics of the flow at Re = 1000 are discussed and analyzed in detail. Major phenomena revealed by the numerical computations include the downward concentration of the fluid through the curved shock, the formation of the vortices, the mechanism of the shock wave bifurcation, the structure of the jet along the bottom wall, and the Kelvin-Helmholtz instability near the contact surface. Presentation and analysis of those flow processes provide important physical insight into the complex flow physics occurring in a shock tube.
Broadband graphene-based metamaterial absorbers
Authors: Liu Chang , Qi Limei , Zhang Xu
Published: January 2018

In this paper, a new type of broadband tunable metamaterial absorber is proposed. The structure consists of a single-layer ring graphene and a metal ground plane separated by a dielectric spacer. The graphene rings are connected each other to be easily tuned by the voltage. In addition, this absorber is polarization-independent at normal incidence due to the symmetric pattern of the unit cell. Results reveal the bandwidth of 90% absorption reaches to 2.25 THz for a single-ring structure. The bandwidth of 90% absorption increases to 3.2 THz by combining two similar rings with different sizes in one unit cell. The physical mechanism of the single-ring and dual-ring absorbers are given based on the impedance matching theory.
Theoretical prediction of high electron mobility in multilayer MoS2 heterostructured with MoSe2
Authors: Ji Liping , Shi Juan , Zhang Z. Y. , Wang Jun , Zhang Jiachi , Tao Chunlan , Cao Haining
Published: January 2018

Two-dimensional (2D) MoS2 has been considered to be one of the most promising semiconducting materials with the potential to be used in novel nanoelectronic devices. High carrier mobility in the semiconductor is necessary to guarantee a low power dissipation and a high switch speed of the corresponding electronic device. Strain engineering in 2D materials acts as an important approach to tailor and design their electronic and carrier transport properties. In this work, strain is introduced to MoS2 through perpendicularly building van der Waals heterostructures MoSe2–MoS2. Our first-principles calculations demonstrate that acoustic-phonon-limited electron mobility can be significantly enhanced in the heterostructures compared with that in pure multilayer MoS2. It is found that the effective electron mass and the deformation potential constant are relatively smaller in the heterostructures, which is responsible for the enhancement in the electron mobility. Overall, the electron mobility in the heterostructures is about 1.5 times or more of that in pure multilayer MoS2 with the same number of layers for the studied structures. These results indicate that MoSe2 is an excellent material to be heterostructured with multilayer MoS2 to improve the charge transport property.
On the formation modes in vortex interaction for multiple co-axial co-rotating vortex rings
Authors: Qin Suyang , Liu Hong , Xiang Yang
Published: January 2018

Interaction among multiple vortices is of particular importance to biological locomotion. It plays an essential role in the force and energy capture. This study examines the motion and dynamics of multiple co-axial co-rotating vortex rings. The vortex rings, which have the same formation time, are successively generated in a piston-cylinder apparatus by accurately controlling the interval time. The flow fields are visualized by the finite-time Lyapunov exponent and then repelling Lagrangian coherent structures (r-LCSs) are determined. Two types of vortex interactions (“strong” and “weak”) are defined by investigating the r-LCSs: a strong interaction is indicated by connected r-LCSs showing a channel for fluid transport (termed as a “flux window”); a weak interaction is indicated by disconnected r-LCSs between the vortex rings. For strong interaction, leapfrogging and merger of vortex rings can happen in the later stage of the evolution process; however, the rings are separated for weak interaction. Two distinct formation modes, the formation enhancement mode (FEM) and formation restraint mode (FRM), refer to the effect of one or multiple vortex ring(s) on the initial circulation of the subsequently formed vortex ring. In the FEM, the circulation of a vortex ring is larger than that of an isolated (without interaction) vortex ring. On the other hand, the situation is opposite in the FRM. A dimensionless number reflecting the interaction mechanism, “structure stretching number” S*, is proposed, which evaluates the induced effect of the wake vortices on the formation of a vortex ring. A limiting S* (SL*=(2±0.4)×10−4) is the bifurcation point of the two formation modes. The augmentation of circulation reaches up to 10% for the FEM when S*SL*), the circulation decreases for at most 20%. The newly defined formation modes and number could shed light on the understanding of the dynamics of multiple vortex ring flows.
Failure mechanism of resistance-spot-welded specimens impacted on base material by bullets
Authors: Fan Chunlei , Ma Bohan , Chen Danian , Wang Huanran , Ma Dongfang
Published: January 2018

The tests of bullet impact on the base material (BM) of a simple specimen with a single resistance-spot-welded (RSW) nugget of TRIP800 steel are performed to investigate the response of the RSW specimen to the ballistic debris impact on the RSW specimen. A one-stage gas gun is used to fire the bullets while a laser velocity interferometer system for any reflector (VISAR) is used to measure the velocity histories of the free surfaces of the RSW specimen. The recovered RSW specimens are examined with the three-dimensional super depth digital microscope (SDDM) and the scanning electro microscope (SEM). For the tests of small multiple-bullet impact, it is revealed that the wave train of the VISAR measured results and the detachment of the base material interfaces in the recovered RSW specimens are directly related to the reflection and refraction of the curved stress waves incoming to the interfaces and the free surfaces in the RSW specimens. The detachment of BM interfaces can lead to the impact failure of the RSW joints for the larger multiple-bullet impact at higher velocity, the mechanism of which is different from the case for normal incidence (spalling). For the tests of single large bullet impact, it is brought to light experimentally that the plastic strain concentration at the “notch tip” spurs either the crack near the RSW joint or the split of the nugget. The numerical simulation shows up the process of splitting the nugget: a crack initiates at the “notch tip”, propagates across the nugget interface and splits the nugget into two parts. It is indicated that the interaction between the stress waves and many interfaces/free surfaces in the RSW specimen under ballistic impact causes variable local stress triaxialities and stress Lode angles, which affects the deformation and fracture mechanism of the RSW specimen including stretching and shearing failure. It is shown that the impact failure of the RSW joints is a mixture of brittle fracture and ductile fracture while the fracture or perforation of the BM is ductile.
An integrative time-varying frequency detection and channel sounding method for dynamic plasma sheath
Authors: Shi Lei , Yao Bo , Zhao Lei , Liu Xiaotong , Yang Min , Liu Yanming
Published: January 2018

The plasma sheath-surrounded hypersonic vehicle is a dynamic and time-varying medium and it is almost impossible to calculate time-varying physical parameters directly. The in-fight detection of the time-varying degree is important to understand the dynamic nature of the physical parameters and their effect on re-entry communication. In this paper, a constant envelope zero autocorrelation (CAZAC) sequence based on time-varying frequency detection and channel sounding method is proposed to detect the plasma sheath electronic density time-varying property and wireless channel characteristic. The proposed method utilizes the CAZAC sequence, which has excellent autocorrelation and spread gain characteristics, to realize dynamic time-varying detection/channel sounding under low signal-to-noise ratio in the plasma sheath environment. Theoretical simulation under a typical time-varying radio channel shows that the proposed method is capable of detecting time-variation frequency up to 200 kHz and can trace the channel amplitude and phase in the time domain well under –10 dB. Experimental results conducted in the RF modulation discharge plasma device verified the time variation detection ability in practical dynamic plasma sheath. Meanwhile, nonlinear phenomenon of dynamic plasma sheath on communication signal is observed thorough channel sounding result.
Realization of spin wave switch for data processing
Authors: Balinskiy M. , Chiang H. , Khitun A.
Published: January 2018

In this work, experimental data on a spin wave switch based on spin wave interference is reported. The switch is a three terminal device where spin wave propagation between the source and the drain is modulated by the control spin wave signal. The prototype is a micrometer scale device based on Y3Fe2(FeO4)3 film. The output characteristics show the oscillation of the output spin wave signal as a function of the phase difference between the source and the drain spin wave signals. The On/Off ratio of the prototype exceeds 20 dB at room temperature. The utilization of phase in addition to amplitude for information encoding offers an innovative route towards multi-state logic circuits. The advantages and shortcomings of spin wave switches are also discussed.
High-power broadband plasma maser with magnetic self-insulation
Authors: Litvin Vitaliy O. , Loza Oleg T.
Published: January 2018

Presented in this paper are the results of a particle-in-cell modelling of a novel high-power microwave (HPM) source which combines the properties of two devices. The first prototype is a magnetically insulated transmission line oscillator (MILO), an HPM self-oscillator which does not need an external magnetic field and irradiates a narrow spectrum depending on its iris-loaded slow-wave structure. The second prototype is a plasma maser, a Cherenkov HPM amplifier driven by a high-current relativistic electron beam propagating in a strong external magnetic field in plasma which acts as a slow-wave structure. The radiation frequency of plasma masers mainly depends on an easily variable plasma concentration; hence, their spectrum may overlap a few octaves. The plasma-based HPM device described in this paper operates without an external magnetic field: it looks like an MILO in which the iris-loaded slow-wave structure is substituted by a hollow plasma tube. The small pulse duration of ∼1.5 ns prevents a feedback rise in the 20-cm long generation section so that the device operates as a noise amplifier. Unlike conventional ultra wideband generators, the spectrum depends not only on the pulse duration but mainly on plasma, so the operation frequency of the device ranges within 12 GHz. For irradiated frequencies above 2 GHz, the total pulse energy efficiency of 7% is demonstrated at the HPM power level ∼1 GW.
A fluid membrane enhances the velocity of cargo transport by small teams of kinesin-1
Authors: Li Qiaochu , Tseng Kuo-Fu , King Stephen J. , Qiu Weihong , Xu Jing
Published: January 2018

Kinesin-1 (hereafter referred to as kinesin) is a major microtubule-based motor protein for plus-end-directed intracellular transport in live cells. While the single-molecule functions of kinesin are well characterized, the physiologically relevant transport of membranous cargos by small teams of kinesins remains poorly understood. A key experimental challenge remains in the quantitative control of the number of motors driving transport. Here we utilized “motile fraction” to overcome this challenge and experimentally accessed transport by a single kinesin through the physiologically relevant transport by a small team of kinesins. We used a fluid lipid bilayer to model the cellular membrane in vitro and employed optical trapping to quantify the transport of membrane-enclosed cargos versus traditional membrane-free cargos under identical conditions. We found that coupling motors via a fluid membrane significantly enhances the velocity of cargo transport by small teams of kinesins. Importantly, enclosing a cargo in a fluid lipid membrane did not impact single-kinesin transport, indicating that membrane-dependent velocity enhancement for team-based transport arises from altered interactions between kinesins. Our study demonstrates that membrane-based coupling between motors is a key determinant of kinesin-based transport. Enhanced velocity may be critical for fast delivery of cargos in live cells.
Tunable magnetic anisotropy of self-assembled Fe nanostructures within a La0.5Sr0.5FeO3 matrix
Authors: Zhang Bruce , Fan Meng , Li Leigang , Jian Jie , Huang Jijie , Wang Han , Kalaswad Matias , Wang Haiyan
Published: January 2018

Metallic nanostructures within ceramic matrices provide a unique platform for integrating magnetic, optical, and electrical properties for device applications. Currently, hurdles still exist for the integration of metallic nanostructures within conventional devices, including the incompatible growth conditions between metals and ceramics and control of the overall physical properties. In this study, we demonstrate the tunability of a one-step growth method to fabricate magnetic and metallic nanostructures embedded within an oxide matrix, La0.5Sr0.5FeO3:Fe, from a composite target using pulsed laser deposition. The metal-ceramic nanocomposite films demonstrate tunable nanostructures and anisotropic magnetic response by varying deposition energy, presenting a mechanism for tuning the physical properties of vertically aligned ferromagnetic metallic nanopillars in an oxide matrix. This study also opens avenues towards the integration of nanoscale, vertical, metallic ferromagnetic contacts for anisotropic magnetic tunneling junctions which may not be easily realized by single-phase thin films.
A β-Ta system for current induced magnetic switching in the absence of external magnetic field
Authors: Chen Wenzhe , Qian Lijuan , Xiao Gang
Published: January 2018

Magnetic switching via Giant Spin Hall Effect (GSHE) has received great interest for its role in developing future spintronics logic or memory devices. In this work, a new material system (i.e. a transition metal sandwiched between two ferromagnetic layers) with interlayer exchange coupling is introduced to realize the deterministic field-free perpendicular magnetic switching. This system uses β-Ta, as the GSHE agent to generate a spin current and as the interlayer exchange coupling medium to generate an internal field. The critical switching current density at zero field is on the order of 106 A/cm2 due to the large spin Hall angle of β-Ta. The internal field, along with switching efficiency, depends strongly on the orthogonal magnetization states of two ferromagnetic coupling layers in this system.
Loss and redistribution of energetic passing ions with resonant magnetic perturbations
Authors: Xu Yingfeng , Guo Wenfeng , Ye Lei , Xiao Xiaotao , Wang Shaojie , Zhu Siqiang
Published: January 2018

The effects of resonant magnetic perturbations (RMPs) and the magnetic drift on the loss and redistribution of passing ions are investigated numerically by the upgrade version of the orbit following code GYCAVA. The drift island structures of passing ion orbits induced by RMPs and the magnetic drift are consistent with the given toroidal and poloidal mode numbers of RMPs in the orbit simulations. The redistribution and loss of energetic and thermal passing ions with and without RMPs are numerically studied and compared with each other. The redistribution near the edge is due to the loss induced by RMPs and the magnetic drift. The extra loss of passing ions induced by RMPs is related to the drift island structure induced by RMPs and the magnetic drift and the stochasticity induced by overlap of magnetic islands. The loss of passing ions with n = 1 RMPs is larger than that with n = 4 RMPs for the same perturbation amplitude parameter, which is due to the fact that the magnetic islands produced by n = 1 RMPs are larger than those produced by n = 4 RMPs. The loss fraction of passing ions with n = 1 RMPs increases with the amplitude of RMPs and the radial profile parameter of the ion density. The pitch and energy scan for the loss of energetic passing ions with n = 1 RMPs is simulated. For counter-passing ions, the loss fraction of low-pitch ions is larger than that of high-pitch ions. The dependence of the loss of energetic ions with RMPs on energy is related to the pitch angle.
Current-driven domain wall dynamics in ferromagnetic layers synthetically exchange-coupled by a spacer: A micromagnetic study
Authors: Alejos Oscar , Raposo Victor , Sanchez-Tejerina Luis , Tomasello Riccardo , Finocchio Giovanni , Martinez Eduardo
Published: January 2018

The current-driven domain wall motion along two exchange-coupled ferromagnetic layers with perpendicular anisotropy is studied by means of micromagnetic simulations and compared to the conventional case of a single ferromagnetic layer. Our results, where only the lower ferromagnetic layer is subjected to the interfacial Dzyaloshinskii-Moriya interaction and to the spin Hall effect, indicate that the domain walls can be synchronously driven in the presence of a strong interlayer exchange coupling, and that the velocity is significantly enhanced due to the antiferromagnetic exchange coupling as compared with the single-layer case. On the contrary, when the coupling is of ferromagnetic nature, the velocity is reduced. We provide a full micromagnetic characterization of the current-driven motion in these multilayers, both in the absence and in the presence of longitudinal fields, and the results are explained based on a one-dimensional model. The interfacial Dzyaloshinskii-Moriya interaction, only necessary in this lower layer, gives the required chirality to the magnetization textures, while the interlayer exchange coupling favors the synchronous movement of the coupled walls by a dragging mechanism, without significant tilting of the domain wall plane. Finally, the domain wall dynamics along curved strips is also evaluated. These results indicate that the antiferromagnetic coupling between the ferromagnetic layers mitigates the tilting of the walls, which suggest these systems to achieve efficient and highly packed displacement of trains of walls for spintronics devices. A study, taking into account defects and thermal fluctuations, allows to analyze the validity range of these claims.
Parameter identification based on modified simulated annealing differential evolution algorithm for giant magnetostrictive actuator
Authors: Gao Xiaohui , Liu Yongguang
Published: January 2018

There is a serious nonlinear relationship between input and output in the giant magnetostrictive actuator (GMA) and how to establish mathematical model and identify its parameters is very important to study characteristics and improve control accuracy. The current-displacement model is firstly built based on Jiles-Atherton (J-A) model theory, Ampere loop theorem and stress-magnetism coupling model. And then laws between unknown parameters and hysteresis loops are studied to determine the data-taking scope. The modified simulated annealing differential evolution algorithm (MSADEA) is proposed by taking full advantage of differential evolution algorithm’s fast convergence and simulated annealing algorithm’s jumping property to enhance the convergence speed and performance. Simulation and experiment results shows that this algorithm is not only simple and efficient, but also has fast convergence speed and high identification accuracy.
3D analysis of semiconductor devices: A combination of 3D imaging and 3D elemental analysis
Authors: Fu Bianzhu , Gribelyuk Michael A.
Published: January 2018

3D analysis of semiconductor devices using a combination of scanning transmission electron microscopy (STEM) Z-contrast tomography and energy dispersive spectroscopy (EDS) elemental tomography is presented. 3D STEM Z-contrast tomography is useful in revealing the depth information of the sample. However, it suffers from contrast problems between materials with similar atomic numbers. Examples of EDS elemental tomography are presented using an automated EDS tomography system with batch data processing, which greatly reduces the data collection and processing time. 3D EDS elemental tomography reveals more in-depth information about the defect origin in semiconductor failure analysis. The influence of detector shadowing and X-rays absorption on the EDS tomography's result is also discussed.
Investigation of c-axis-aligned crystalline gadolinium doped aluminum-zinc-oxide films sputtered at room-temperature
Authors: Dong Junchen , Li Huijin , Han Dedong , Yu Wen , Luo Zhen , Liang Yi , Zhang Shengdong , Zhang Xing , Wang Yi
Published: January 2018

The c-axis-aligned crystalline (CAAC) rare earth gadolinium doped aluminum-zinc-oxide (Gd-AZO) thin films sputtered at room temperature are investigated in this work. It is found that the polycrystalline AZO is restructured into CAAC Gd-AZO through gadolinium doping. The X-ray diffraction spectrum and high-resolution transmission electron microscopy images indicate the (002) crystalline orientation of the local Gd-AZO grains. The film-formation mechanism of room-temperature sputtered CAAC Gd-AZO thin films is analyzed. Bottom gate oxide thin film transistors with a Gd-AZO active layer are fabricated by low temperature processes. The devices show preferable electrical properties, such as good I-V characteristics, high uniformity, and excellent bias stress stability.
Magnetoelectric coupling of a magnetoelectric flux gate sensor in vibration noise circumstance
Authors: Chu Zhaoqiang , Shi Huaduo , Gao Xiangyu , Wu Jingen , Dong Shuxiang
Published: January 2018

A magnetoelectric (ME) flux gate sensor (MEFGS) consisting of piezoelectric PMN-PT single crystals and ferromagnetic amorphous alloy ribbon in a self-differential configuration is featured with the ability of weak magnetic anomaly detection. Here, we further investigated its ME coupling and magnetic field detection performance in vibration noise circumstance, including constant frequency, impact, and random vibration noise. Experimental results show that the ME coupling coefficient of MEFGS is as high as 5700 V/cm*Oe at resonant frequency, which is several orders magnitude higher than previously reported differential ME sensors. It was also found that under constant and impact vibration noise circumstance, the noise reduction and attenuation factor of MEFGS are over 17 and 85.7%, respectively. This work is important for practical application of MEFGS in real environment.
Convective hydromagnetic instabilities of a power-law liquid saturating a porous medium: Flux conditions
Authors: Chahtour C. , Ben Hamed H. , Beji H. , Guizani A. , Alimi W.
Published: January 2018

We investigate how an external imposed magnetic field affects thermal instability in a horizontal shallow porous cavity saturated by a non-Newtonian power-law liquid. The magnetic field is assumed to be constant and parallel to the gravity. A uniform heat flux is applied to the horizontal walls of the layer while the vertical walls are adiabatic. We use linear stability analysis to find expressions for the critical Rayleigh number as a function of the power-law index and the intensity of the magnetic field. We use nonlinear parallel flow theory to find some explicit solutions of the problem, and we use finite difference numerical simulations to solve the full nonlinear equations. We show how the presence of magnetic field alters the known hydrodynamical result of Newtonian flows and power-law flows and how it causes the presence of subcritical finite amplitude convection for both pseudoplastic and dilatant fluids. We also show that in the limit of very strong magnetic field, the dissipation of energy by Joule effect dominates the dissipation of energy by shear stress and gives to the liquid an inviscid character.
Kelvin probe force microscopy studies of the charge effects upon adsorption of carbon nanotubes and C60 fullerenes on hydrogen-terminated diamond
Authors: Kölsch S. , Fritz F. , Fenner M. A. , Kurch S. , Wöhrl N. , Mayne A. J. , Dujardin G. , Meyer C.
Published: January 2018

Hydrogen-terminated diamond is known for its unusually high surface conductivity that is ascribed to its negative electron affinity. In the presence of acceptor molecules, electrons are expected to transfer from the surface to the acceptor, resulting in p-type surface conductivity. Here, we present Kelvin probe force microscopy (KPFM) measurements on carbon nanotubes and C60 adsorbed onto a hydrogen-terminated diamond(001) surface. A clear reduction in the Kelvin signal is observed at the position of the carbon nanotubes and C60 molecules as compared with the bare, air-exposed surface. This result can be explained by the high positive electron affinity of carbon nanotubes and C60, resulting in electron transfer from the surface to the adsorbates. When an oxygen-terminated diamond(001) is used instead, no reduction in the Kelvin signal is obtained. While the presence of a charged adsorbate or a difference in work function could induce a change in the KPFM signal, a charge transfer effect of the hydrogen-terminated diamond surface, by the adsorption of the carbon nanotubes and the C60 fullerenes, is consistent with previous theoretical studies.
Transient visual pathway critical for normal development of primate grasping behavior
Authors: Mundinano Inaki-Carril , Fox Dylan M. , Kwan William C. , Vidaurre Diego , Teo Leon , Homman-Ludiye Jihane , Goodale Melvyn A. , Leopold David A. , Bourne James A.
Published: January 2018

Significance

Visually guided actions have been central to the neural and behavioral evolution of primates, culminating in precision grasping and object manipulation. Here, we reveal that the establishment and maturation of the cortical areas controlling reach-and-grasp behaviors are dependent on a transient visual pathway from the retina to the medial inferior pulvinar of the thalamus, which relays the information to the dorsal stream of the visual cortex, via the middle temporal (MT) area, in early life. Disruption of this pathway in early life leads to permanent anatomical, connectional, and reach-and-grasp behavior deficits.