bluuebunny/crossref_metadata_2025_split huggingface dataset:
Symbolic finite element discretization and model order reduction of a multiphysics model for IPMC sensors
Authors: Kondo Kota , Takagi Kentaro , Zhu Zicai , Asaka Kinji 
Published: August 2020

Abstract
The multiphysics model of ionic polymer-metal composite (IPMC) sensors proposed by Zhu has a significant advantage of being able to describe the dynamic sensor response, which highly depends on humidity, by explicitly considering solvent dynamics. However, it is difficult to perform analysis and simulation because Zhu’s model is represented by complex non-linear partial differential equations. This paper describes the symbolic finite element discretization of Zhu’s model and further discusses the essential dynamics of the reduced-order model extracted from the finite element model. The obtained linear ordinary differential equations, or the state equation, can be easily implemented in simulators via common programming languages. The simulation results of an in-house simulator implemented by MATLAB code show good agreement with those of direct numerical simulation by using commercial software, COMSOL. To further simplify the model, the minimum order required for an appropriate approximation is numerically investigated by using a model order reduction technique. This paper reveals that the dynamic response of an IPMC sensor can be consequently approximated by a first-order or second-order linear time-invariant system.
A novel piezoelectric linear actuator designed by imitating skateboarding movement
Authors: Wang Kuifeng , Li Xuan , Sun Wuxiang , Yang Zhixin , Liang Tianwei , Huang Hu 
Published: August 2020

Abstract
By imitating skateboarding movement, a novel stick–slip piezoelectric linear actuator was proposed in this study. A specific flexure driving foot mechanism (FDFM) was designed to realize the bionic driving function, and theoretical analysis was conducted to calculate the displacement amplification ratio of the FDFM which was further confirmed by finite element simulation. Being different from most of previous design that the slider moved and the driving mechanism was fixed, here the FDFM was integrated with the slider and they moved together along the guide rail. Being similar to that the train moved along the tracks, this kind of layout would facilitate the realization of larger working stroke of the actuator. By experiments, output characteristics of the designed actuator under various driving frequencies and voltages were tested. The results showed that by changing the waveform of driving voltage, both forward and reverse motions with good linearity and stability could be easily achieved. The speed of reverse motion was higher than that of forward motion because of the relatively larger backward motion during forward motion, which was due to the promotion of deformation recovery of the FDFM. Furthermore, the resolution and loading capacity were characterized. The resolutions of forward and reverse motions were 47 nm and 45 nm, respectively, and the actuator could achieve a relatively stable speed when the vertical load was in the range of 0–2 N. This study is expected to provide a new idea for designing piezoelectric actuators with features of high speed, high stability and large working stroke.
Joint characteristics of ultrasonic welded CC bridge joints for HTS coil applications
Authors: Shin Hyung-Seop , Jung Chan-Hun , Nisay Arman Ray 
Published: August 2020

Abstract
Long lengths of second-generation REBCO coated conductor (CC) tapes must be joined together when power cables, coils, and magnets requiring kilometer-scale lengths are fabricated. Various resistive joining techniques of CC tapes, such as soldering and diffusion reaction, have been studied. The joint method should provide good adhesion, low joint resistance (R
j), no critical current (I
c) degradation, cost effectiveness, and simplicity in processing. An ultrasonic welding (UW) process was developed and used to form various types of CC joint structures, such as lap- and butt-joints, using differently stabilized REBCO CC tapes. In this study, the UW process was used to form various bridge-joints of CC tapes for high-temperature superconducting coils. A mechanical-controlled soldering method which has provided a low contact resistance was also adopted for comparison. CC joints of various structures were fabricated using UW and soldering, and the retained I
c and R
j were measured at 77 K and self-field in each. The electromechanical properties of the CC bridge-joints were evaluated using a bending test. Results showed that R
j varied in the CC joints depending on the structure type and joint area. Moreover, the additional Sn layer in Cu-stabilized CC tapes improved R
j in each joint structure because it provided a solder-like bond at the joint interface. The bridge-joints formed using UW showed comparable bending diameter tolerances for irreversible I
c degradation to those formed using mechanically controlled soldering. The multiple 4 mm wide CC bridges provided more flexibility at the joint part due to gaps between bridges and resulted to a better tolerance to tension bending than the single 12 mm wide ones.
Vortex phase diagram in 12442-type RbCa2Fe4As4F2 single crystal revealed by magneto-transport and magnetization measurements
Authors: Xing Xiangzhuo , Yi Xiaolei , Li Meng , Meng Yan , Mu Gang , Ge Jun-Yi , Shi Zhixiang 
Published: August 2020

Abstract
The recently discovered 12442-type ACa2Fe4As4F2 (A = K, Rb, Cs) compounds are the only iron-based superconductors (IBSs) with double FeAs layers between neighboring insulating layers, analogous to the double CuO2 layers in some high-T
c cuprates. Here, we report the study of vortex phase diagram of RbCa2Fe4As4F2 single crystal via magneto-transport and magnetization measurements. The resistive transition under magnetic fields shows a foot-like kink at a characteristic temperature, T
s, followed by a resistive tail in nearly zero resistivity region. Such behavior is ascribed to a vortex slush transition at T
s, below which the vortex state has short-range vortex lattice correlation, and then a second-order transition into the vortex glass phase occurs with further decreasing temperature. Above T
s, the Arrhenius plot of resistivity shows two linear regions that are separated by a crossover line T
cr(B), which is associated with a crossover from collective to plastic pinning or different flux pinning behaviors resulted from different types of defect. In addition, the magnetic hysteresis loops reveal a second magnetization peak (SMP), which is shifted to lower fields with increasing temperature for T< 12 K. However, the SMP unexpectedly moves back to a higher field at T= 12 K, and then gradually turns into a shoulder or kink that moves to higher fields at high temperatures, such anomalous behavior has never been observed in IBSs. According to the magneto-transport and magnetization data, the vortex phase diagram of RbCa2Fe4As4F2 is finally constructed. Details on the different vortex phase transitions and relevant physical scenarios are given and discussed.
Quasiclassical approach to synergic synchrotron–Cherenkov radiation in polarized vacuum
Authors: Artemenko I I , Nerush E N , Kostyukov I Yu 
Published: August 2020

Abstract
Photon emission by an ultrarelativistic charged particle in extremely strong magnetic field is analyzed, with vacuum polarization and photon recoil taken into account. Vacuum polarization is treated phenomenologically via refractive index. The photon emission occurs in the synergic (cooperative) synchrotron–Cherenkov process [J Schwinger et al 1976 Annals of Physics
96 303] which is similar to the synchrotron emission rather than to the Cherenkov one. For electrons, the effect of vacuum polarization on the emission spectrum is not evident at least below the probable onset of non-perturbative quantum electrodynamics (QED). However, the effect of vacuum polarization on the emission spectrum can be observable for muons already at γB/B

S
≈ 30, with γ the muon Lorentz factor, B the magnetic field strength and B

S
the critical QED field. Nevertheless, vacuum polarization leads to only 10% enhancement of the maximum of the radiation spectrum.
Holographic technicolor model and dark matter *
Authors: Chen Yidian , Bi Xiao-Jun , Huang Mei 
Published: August 2020

Abstract
We investigate the strongly coupled minimal walking technicolor model (MWT) in the framework of a bottom-up holographic model, where the global SU(4) symmetry breaks into

subgroups. In the holographic model, we found that 125 GeV composite Higgs particles and small Peskin–Takeuchi S parameter can be achieved simultaneously. In addition, the model predicts a large number of particles at the TeV scale, including dark matter candidates Technicolor Interacting Massive Particles (TIMPs). If we consider the dark matter nuclear spin-independent cross-section in the range of

, which can be detected by future experiments, the mass range of TIMPs predicted by the holographic technicolor model is

TeV.
Gluon-pair-creation production model of strong interaction vertices *
Authors: Wan Bing-Dong , Qiao Cong-Feng 
Published: August 2020

Abstract
By studying the

exclusive decay to double glueballs, we introduce a model to phenomenologically mimic the gluon-pair-vacuum interaction vertices, namely the

model. Based on this model, we study glueball production in pseudoscalar quarkonium decays, explicitly

,

, and

processes. Among them

and

are well-known scalars possessing large glue components, while

is a potential candidate for a pseudoscalar glueball. The preliminary calculation results indicate that these processes are marginally accessible in the presently running experiments BES III, BELLE II, and LHCb.
Search for the

molecular state

in the reaction

*
Authors: Zhang Yang , Wang En , Li De-Min , Li Yu-Xiao 
Published: August 2020

Abstract
Based on the prediction of a

molecular state

with isospin

in the coupled channel approach, we suggest the search for this state in the reaction

. By considering the final state interactions of

and

and the contribution from the

resonance, we observed that the

mass distribution shows a peak around 4000 MeV, which might be associated with the

molecular state

. The search for

in the reaction

is critical for understanding the internal structures of exotic hadrons. Our predictions can be tested by the Belle II and LHCb in future studies.
Analysis of survival probability based on superasymmetric reaction systems *
Authors: Li Na-Na , Bao Xiao-Jun 
Published: August 2020

Abstract
The survival probability of an excited compound nucleus was studied using two different approaches of the washing out of shell effects with excitation energy based on a superasymmetric reaction system. The estimated evaporation residue cross sections based on the two different methods are compared with the available experimental data. Both methods are in agreement with the experimental data to a certain extent for some specific reactions and xn emission channels.
Emission time sequence of neutrons and protons as probes of α-clustering structure *
Authors: Huang Bo-Song , Ma Yu-Gang 
Published: August 2020

Abstract
Neutron–proton momentum correlation functions are constructed from a three-body photodisintegration channel, i.e., core+n+p, and used to explore the spatial-time information of the non-clustering Woods–Saxon spherical structure as well as the

-clustering structures of

or

based on an extended quantum molecular dynamics model. The emission time sequence of neutrons and protons is indicated by the ratio of velocity-gated neutron–proton correlation functions, demonstrating its sensitivity to

-clustering structures. This work sheds light on a new probe for

-clustering structures.
Systematic study of odd-mass 151-161Pm and 154,156Pm isotopes using projected shell model *
Authors: Rani Veerta , Verma Preeti , Singh Suram , Rajput Manvi , Bharti Arun , Bhat G. H. , Sheikh J. A. 
Published: August 2020

Abstract
Inspired by the availability of recent experimental as well as theoretical data on the energy levels of odd-mass 151-161Pm and odd-odd 154,156Pm, we applied the theoretical framework of the projected shell model to further understand the nuclear structure of these nuclei. The calculations closely reproduced the experimental data reported for the yrast bands of these isotopes by assuming an axial (prolate) deformation of ~0.3. Other properties along the yrast line, such as transition energies and transition probabilities, have also been discussed. Band diagrams are plotted to understand their intrinsic multi-quasiparticle structure, which turn out to be dominated by 1-quasiparticle bands for the odd-mass Pm isotopes and 2-quasiparticle bands for the doubly-odd Pm isotopes under study. The present study not only confirms the recently reported experimental/theoretical data, but also extends the already available information on the energy levels and adds new information regarding the reduced transition probabilities.
Warm tachyon inflation and swampland criteria *
Authors: Mohammadi Abolhassan , Golanbari Tayeb , Sheikhahmadi Haidar , Sayar Kosar , Akhtari Lila , Rasheed M. A. , Saaidi Khaled 
Published: August 2020

Abstract
In this study, the scenario of a two-component warm tachyon inflation is considered, where the tachyon field plays the role of the inflaton by driving the inflation. During inflation, the tachyon scalar field interacts with the other component of the Universe, which is assumed to be photon gas, i.e., radiation. The interacting term contains a dissipation coefficient, and the study is modeled based on two different and familiar choices of the coefficient that were studied in the literature. By employing the latest observational data, the acceptable ranges for the free parameters of the model are obtained. For any choice within the estimated ranges, there is an acceptable concordance between the theoretical predictions and observations. Although the model is established based on several assumptions, it is crucial to verify their validity for the obtained values of the free parameters of the model. It is found that the model is not self-consistent for all values of the ranges, and for some cases, the assumptions are violated. Therefore, to achieve both self-consistency and agreement with the data, the parameters of the model must be constrained. Subsequently, we consider the recently proposed swampland conjecture, which imposes two conditions on the inflationary models. These criteria rule out some inflationary models; however, warm inflation is among those that successfully satisfy the swampland criteria. We conduct a precise investigation, which indicates that the proposed warm tachyon inflation cannot satisfy the swampland criteria for some cases. In fact, for the first case of the dissipation coefficient, in which, there is dependency only on the scalar field, the model agrees with observational data. However, it is in direct tension with the swampland criteria. Nevertheless, for the second case, wherein the dissipation coefficient has a dependency on both the scalar field and temperature, the model exhibits acceptable agreement with observational data, and suitably satisfies the swampland criteria.
Strong gravitational lensing for photon coupled to Weyl tensor in Kiselev black hole
Authors: Abbas G. , Mahmood Asif , Zubair M. 
Published: August 2020

Abstract
The objective of the present work is to highlight the phenomena of strong gravitational lensing and deflection angle for the photon coupling with the Weyl tensor in a Kiselev black hole. Here, we have extended the prior work of Chen and Jing (S. Chen and J. Jing, JCAP, 10: 002 (2015)) for a Schwarzschild black hole to a Kiselev black hole. For this purpose, the equation of motion for the photons coupled to the Weyl tensor, null geodesic, and equation of photon sphere in a Kiselev black hole spacetime have been formulated. It is found that the equation of motion of the photons depends not only on the coupling between the photons and the Weyl tensor, but also on the polarization direction of the photons. There is a critical value of the coupling parameter, α, for the existence of the marginally circular photon orbit outside the event horizon, which depends on the parameters of the black hole and the polarization direction of the photons. Further, the polarization directions of the coupled photons and the coupling parameter,

; both modify the features of the photon sphere, angle of deflection, and functions

and

owing to the strong gravitational lensing in the Kiselev black hole spacetime. In addition to this, the observable gravitational lensing quantities and the shadows of the Kiselev black hole spacetime are presented in detail.
Fine micro-thermal structures for Reissner-Nordström black hole *
Authors: Xu Zhen-Ming , Wu Bin , Yang Wen-Li 
Published: August 2020

Abstract
We solve the condundrum on whether the molecules of the Reissner-Nordström black hole interact through the Ruppeiner thermodynamic geometry, basing our study on the concept of the black hole molecule proposed in [Phys. Rev. Lett. 115 (2015) 111302] and choosing the appropriate extensive variables. Our results show that the Reissner-Nordström black hole is indeed an interaction system that may be dominated by repulsive interaction. More importantly, with the help of a novel quantity, namely the thermal-charge density, we describe the fine micro-thermal structures of the Reissner-Nordström black hole in detail. Three different phases are presented, namely the free, interactive, and balanced phases. The thermal-charge density plays a role similar to the order parameter, and the back hole undergoes a new phase transition between the free phase and interactive phase. The competition between the free phase and interactive phase exists, which leads to extreme behavior of the temperature of the Reissner-Nordström black hole. For the extreme Reissner-Nordström black hole, the entire system is completely in the interactive phase. More importantly, we provide the thermodynamic micro-mechanism for the formation of the naked singularity of the Reissner-Nordström black hole.
Daily dynamics of thunderstorms in the North Caucasus
Authors: Kazakova S T , Yurchenko N V , Gyatov R A , Bekkiev K M 
Published: August 2020

Abstract
Based on instrumental observations for the period from 2008 to 2019, regional features of the regime of daily thunderstorm activity in the North Caucasus are analyzed. Thunderstorm activity is calculated at different periods of the day. The temporal and spatial changes of thunderstorm activity are analyzed by time of day and by month. Temporary trends in thunderstorm activity are shown. The characteristic of the dominant tendency and diurnal features in long-term changes in the main characteristics of thunderstorm activity is given; the role of various factors determining these changes is estimated.
Towards time-dependent wave packet tunnelling via complex Riccati equations
Authors: Bonilla-Licea M , Schuch D 
Published: August 2020

Abstract
Since the discovery of tunnelling in the early days of quantum mechanics, there has been considerable interest in finding an effective method to determine the transmission of wave packets through a potential barrier. In this work, we combine the transfer matrix method, known from stationary tunnelling problems, with the construction of Gaussian wave packets via superposition of stationary states with the knowledge about the dynamics of generalized Gaussian-shaped coherent states in terms of complex Riccati equations. In the low-energy regime, this leads to an approximate analytical expression for the transmission probability and its dynamics. Extension to more general potential shapes appears straightforward.
Symmetry: the search for order in Science
Authors: Iachello F 
Published: August 2020

Abstract
After an historical introduction of the concept of symmetry in art and science, the many ways in which symmetry is used today in science are briefly reviewed. A new concept, super-symmetry, introduced in the 1970’s is also briefly reviewed, and the only experimental example of supersymmetry in science is presented. The future of symmetry in science is briefly discussed.
Protocol for pulsed antihydrogen production in the AEḡIS apparatus
Authors: Tietje I C , Amsler C , Antonello M , Belov A , Bonomi G , Brusa R S , Caccia M , Camper A , Caravita R , Castelli F , Cheinet P , Comparat D , Consolati G , Demetrio A , Noto L Di , Doser M , Fanì M , Ferragut R , Fesel J , Gerber S , Giammarchi M , Gligorova A , Glöggler L T , Guatieri F , Haider S , Hinterberger A , Kellerbauer A , Khalidova O , Krasnický D , Lagomarsino V , Malbrunot C , Nowak L , Mariazzi S , Matveev V , Müller S R , Nebbia G , Nedelec P , Oberthaler M , Oswald E , Pagano D , Penasa L , Petracek V , Povolo L , Prelz F , Prevedelli M , Rienäcker B , Røhne O M , Rotondi A , Sandaker H , Santoro R , Testera G , Toso V , Wolz T , Yzombard P , Zimmer C , Zurlo N 
Published: August 2020

Abstract
The AEḡIS collaboration’s main goal is to measure the acceleration of antihydrogen (

H
¯

) due to gravity. The experimental scheme is to form a pulsed beam whose vertical deflection is then measured by means of a moiré deflectometer [1]. Creating pulsed

H
¯

is crucial since it allows a velocity measurement of the antiatoms via time of flight (ToF) necessary to deduce the gravitational acceleration ḡ from the vertical deflection Δs. The aim of this article is to outline the experimental protocol leading up to pulsed antihydrogen production in the AEḡIS experiment.
Effects of timing and magnitude of wing stroke-plane tilt on the escape maneuverability of flapping wing
Authors: Zhou Chao , Chen Long , Wu Jianghao 
Published: August 2020

Abstract
Hummingbirds perform a variety of agile maneuvers, and one of them is the escape maneuver, in which the birds can steer away from threats using only 3–4 wingbeats in less than 150 ms. A distinct kinematic feature that enables the escape maneuver is the rapid backward tilt of the wing stroke plane at the beginning of the maneuver. This feature results in a simultaneous nose-up pitching and backward acceleration. In this work, we investigated how the magnitude and timing of the wing stroke-plane tilt (relative to the phase of flapping cycle) affected the generation of backward thrust, lift, and pitching moment and therefore the maneuverability of escape flight. Investigations were performed using experiments on dynamically scaled robotic wings and computational fluid dynamic simulation based on a simplified harmonic wing stroke and rotation kinematics at Re = 1000 and hummingbird wing kinematics at Re ≈ 10 000. Results showed that the wing stroke-plane tilt timing exerted a strong influence on the aerodynamic force generation. Independent of the tilt magnitude, the averaged backward thrust and pitching moment were maximized when the stroke plane tilt occurred near the end of the half strokes (e.g., upstroke and downstroke). Relative to the other timings of stroke-plane tilt, the ‘optimal’ timings led to a maximal backward tilt of the total aerodynamic force during the wing upstroke; hence, the backward thrust and nose-up pitching moment increased. The ‘optimal’ timings found in this work were in good agreement with those identified in the escape maneuvers of four species of hummingbirds. Therefore, hummingbirds may use a similar strategy in the beginning of their escape maneuver.