bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of plasma parameters in a pre-breakdown ionization wave at the glow discharge ignition in argon
Authors: Dyatko N A , Ionikh Y Z , Meshchanov A V
Published: January 2021

The results of an experimental study of a pre-breakdown (slow) ionization wave (IW) in argon-filled discharge tubes of 15 mm i.d. and 80 and 100 cm length at a pressure of 1 and 4 Torr are presented. The breakdown and the IW were initiated by a positive voltage pulse with an amplitude of 2 and 4 kV. The IW was detected by the light emitted from its front. The IW emission spectrum consisted of the argon atomic and ion lines. The Ar(763.5 nm) and Ar+(488.0 nm) lines were used to retrieve the electric field strength value in the IW front. For this, the intensity ratio of these lines was measured. The upper levels for these lines are excited by electron impact, and, due to a large difference between their excitation energies, this ratio strongly depends on the reduced electric field strength E/N (E is the electric field strength, N is the atom number density). Theoretical modeling makes it possible to find a relation between the line intensity ratio and the E/N value. In the model, the axial profile of the IW electric field is approximated by a rectangle with a width determined from the measured emission intensity waveform and the wave velocity. As a result, the E/N magnitude in the IW front was found for various positions along the tube. Emission intensity of the DC discharge was also measured, which allowed us to estimate the emitting level population and electron number density in the IW front. The density of seed electrons ahead of the wave is also evaluated and processes responsible for the appearance of these electrons are discussed.
Local electron and ion density control using passive resonant coils in inductively coupled plasma
Authors: Kim Tae-Woo , Lee Moo-Young , Hong Young-Hun , Lee Moo-Hyun , Kim Ju-Ho , Chung Chin-Wook
Published: January 2021

Control of local electron and ion density using passive resonant coils is experimentally investigated in an inductive argon discharge. Four passive resonant coils are installed under a powered coil; each coil has a fan shape and good azimuthal symmetry. Electron energy probability functions and two-dimensional ion density profiles were measured under both resonant and non-resonant regimes. At non-resonance, almost all of the current flows through the powered coil located in the center of the reactor, and the profiles of the electron and ion density are convex. However, at resonance, a large current flows through the passive resonant coil, and dramatic changes are observed in the electron and ion density profiles. At resonance, the electron and ion densities near the passive resonant coil are increased by 300% compared to the non-resonant condition, and radial distributions become almost flat. Experimental results show that the electron and ion density profiles can be effectively controlled by a passive resonant coil at both low pressure (5 mTorr) and high pressure (50 mTorr). These changes in electron and ion density profiles can be understood by the changes of the electron heating and ionization regions.
Effects of RF bias frequency and power on the plasma parameters and ash rate in a remote plasma source
Authors: Zhang Aixian , Lee Moo-Young , Lee Ho-Won , Moon Ho-Jun , Chung Chin-Wook
Published: January 2021

The effects of the RF bias frequency (2–27.12 MHz) and power (0–50 W) on plasma parameters, i.e., effective electron temperatures, electron densities, and electron energy probability functions (EEPFs), were investigated in a remote plasma source. A small cylindrical Langmuir probe based on the Druyvesteyn method was used for the measurements. When the bias power was changed from 0 W to 10 W for each bias frequency, the electron density decreased and the effective electron temperature increased at a given antenna power. As the 2 MHz bias power increased to 50 W, the electron density increased remarkably, whereas the effective electron temperature decreased. Simultaneously, the EEPF evolved from a Druyvesteyn-like distribution to a nearly Maxwellian distribution. In contrast to 2 MHz, when increasing the bias power of 12.5 MHz or 27.12 MHz, there was no distinct change in the effective electron temperature by the bias power and the electron density increased slightly or barely changed. Moreover, the EEPFs retained a Druyvesteyn-like distribution during the bias power increase. These results reveal that the plasma parameters are more controllable at lower bias frequencies, and the analysis is presented in relation to the electron heating mechanism. Therewithal, the ash rate for a 2 MHz bias power was observed to be the highest among the three frequencies when the discharge was operated with pure oxygen.
Cantilever-based micro thrust measurement and pressure field distribution of biomimetic robot fish actuated by macro fiber composites (MFCs) actuators
Authors: Meng Haofeng , Lou Junqiang , Chen Tehuan , Xu Chao , Chen Hairong , Yang Yiling , Cui Yuguo
Published: January 2021

Underwater autonomous vehicles (UAVs) actuated by smart actuators have attracted increasing attention. A miniature macro fiber composite (MFC)-actuated robot fish inspired by koi fish is developed. A cantilever mechanism is designed to transfer the dynamic micro thrust of the robot fish. Three design indexes, namely the bending stiffness, the ratio of the bending stiffness to the torsional stiffness, and the natural frequency of the cantilever transducer are proposed. Thus, a simple and effective method to determine the structural parameters of the cantilever-based micro thrust force measurement system is presented. Calibration results demonstrated that the parameters of the proposed cantilever transducer match well with the designed indexes. Dynamic variation mechanisms of the micro thrust force associated with the swimming behaviors of the robot fish are well captured using the proposed measurement system. Experimental results show that the MFC-actuated robot fish obtains the biggest mean thrust of 1.73 mN in the case of the largest oscillating velocity. The maximum instant thrust grows with the increment of the oscillating frequency, and achieves its maximum of 7.35 mN in the case of 10 Hz. While the maximum instant drag first decreases then increases as the actuation frequency increases, and obtains its minimum of −2.62 mN in the case of the maximum oscillating velocity. On the contrary, variations of the thrust pattern/oscillating period are reversed to those of the maximum instant drag. Computational fluid dynamics results demonstrate that variations of the instant thrust are fully determined by the distribution and intensity of the concentrated pressure regions induced by the oscillating caudal fin. The cycle-averaged velocity fields are closely related to the mean thrust generated by the MFC-actuated robot fish. As a result, the fluid–structure interaction mechanisms associated with the thrust variations of the MFC-actuated robot fish are revealed. This study may be useful for the design and realization of UAVs actuated by smart actuators.
Electromagnetic-thermal-mechanical behaviors of a no-insulation double-pancake coil induced by a quench in the self field and the high field
Authors: Liu Donghui , Li Dongke , Zhang Weiwei , Yong Huadong , Zhou Youhe
Published: January 2021

High-temperature superconducting double-pancake (DP) coils wound by the no-insulation (NI) approach have been proved to have a high thermal stability and a self-protecting ability. This paper mainly studies the effect of a quench of one pancake coil on the electromagnetic-thermal-mechanical behaviors of an NI DP coil in the self field and the high field. An electromagnetic-thermal coupling quench model is used to calculate the distributions of current, temperature and electromagnetic field in the coil, and then a three-dimensional homogeneous mechanical model is built to analyze the changes in strain and stress during a quench by considering the distributions of thermal strain and Lorentz force of the coil. The results indicate that the obvious increase in circumferential current and radial current density in the bottom pancake coil is induced by a quench of the top pancake coil due to the electromagnetic coupling effect in the self field and the high field, and that the DP coil still has a negative coil voltage during a quench in different fields. Although the bottom pancake coil has a large circumferential current, the mechanical deformation of the DP coil during a quench is mainly caused by the temperature rise in the self field. The thermal expansion of the top pancake coil has a remarkable effect on the mechanical behaviors of the bottom pancake coil. Moreover, the DP coil has the same temperature rise and mechanisms of bypass current in the self field and the high field. However, the mechanical deformation of the DP coil is based on the combined effects of temperature rise and Lorentz force in the high field. It can be found that the values of the hoop and axial stresses are affected by a large electromagnetic stress.
Thermal response of the iron-based Ba122 superconductor to in situ and ex situ processes
Authors: Tokuta Shinnosuke , Yamamoto Akiyasu
Published: January 2021

The thermal properties are one of the key parameters to control phase purity and microstructure of polycrystalline materials. The melting point of the iron-based BaFe2As2 superconductor (Ba122), which foresees high-field applications, remains controversial. In this work, thermogravimetry-differential scanning calorimetry measurements (TG-DSC) of undoped and Co-doped Ba122 were carried out. Mixtures of elemental metals and pre-reacted Ba122 powders were prepared to investigate the thermal responses during in situ and ex situ synthesis routes, respectively. In addition, the phases and microstructures of the quenched samples were evaluated to elucidate the observed exothermic/endothermic peaks. Our results suggest that the melting point of Ba122 is ∼1300 °C.
Enhancing the performance of superconducting nanowire-based detectors with high-filling factor by using variable thickness
Authors: Baghdadi Reza , Schmidt Ekkehart , Jahani Saman , Charaev Ilya , Müller Michael G W , Colangelo Marco , Zhu Di , Ilin Konstantin , Semenov Alexej D , Jacob Zubin , Siegel Michael , Berggren Karl K
Published: January 2021

Current crowding at bends of superconducting nanowire single-photon detector (SNSPD) is one of the main factors limiting the performance of meander-style detectors with large filling factors. In this paper, we propose a new concept to reduce the influence of the current crowding effect, a so-called variable thickness SNSPD, which is composed of two regions with different thicknesses. A larger thickness of bends in comparison to the thickness of straight nanowire sections locally reduces the current density and reduces the suppression of the critical current caused by current crowding. This allows variable thickness SNSPD to have a higher critical current, an improved detection efficiency, and decreased dark count rate in comparison with a standard uniform thickness SNSPD with an identical geometry and film quality.
Fiber optic quench detection for large-scale HTS magnets demonstrated on VIPER cable during high-fidelity testing at the SULTAN facility
Authors: Salazar Erica E , Badcock Rodney A , Bajko Marta , Castaldo Bernardo , Davies Mike , Estrada Jose , Fry Vincent , Gonzales Jofferson T , Michael Philip C , Segal Michael , Vieira Rui F , Hartwig Zachary S
Published: January 2021

Fiber-optic thermometry has the potential to provide rapid and reliable quench detection for emerging large-scale, high-field superconducting magnets fabricated with high-temperature-superconductor (HTS) cables. Developing non-voltage-based quench detection schemes, such as fiber Bragg grating (FBG) technology, are particularly important for applications such as magnetic fusion devices where a high degree of induced electromagnetic noise impose significant challenges on traditional voltage-based quench detection methods. To this end, two fiber optic quench detection techniques—FBG and ultra-long FBG (ULFBG)—were incorporated into two vacuum pressure impregnated, insulated, partially transposed, extruded, and roll-formed (VIPER) high-current HTS cables and tested in the SULTAN facility, which provides high-fidelity operating conditions to large-scale superconducting magnets. During surface heater induced quench-like events under a variety of operating conditions, FBG and ULFBG demonstrated strong signal-to-noise ratios (SNRs) ranging from 4 to 32 and measured single-digit temperature excursions; both the SNR and temperature sensitivity increase with temperature. Fiber thermal response times ranged between effectively instantaneous to a few seconds depending on the operating temperature. Strain sensitivity dominates the thermal sensitivity in the conditions achievable at SULTAN; however, measurements at higher quench evolution temperatures, coupled to future work to increase the thermal-to-strain signal, show promise for quench detection capability in full-scale magnets where temperature and strain may occur simultaneously. Overall, FBG and ULFBG were proven capable to quickly and reliably detect small temperature disturbances which induced quench initiation events for high current VIPER HTS conductors in realistic operating conditions, motivating further work to develop FBG and ULFGB quench detection systems for full-scale HTS magnets.
Uniform analysis of electronic sputtering in amorphizable and non-amorphizable insulators and semiconductors
Authors: Szenes G
Published: January 2021

Published experimental data on the variation of the Y sputtering yield with the Se electronic stopping power are analyzed. Systematic results for amorphizable (SiO2, SrCeO3, SrTiO3, CeO2) and non- amorphizable (LiF, KBr) insulators and semiconducting TiO2, ZnO, SiC, UO2 are used. Thermal activation mechanism of electronic sputtering is assumed. The ion-induced temperature is estimated applying the Analytical Thermal Spike Model. A highly accurate description of the experimental Y-Se data is given in the whole range of Se without the application of individual materials parameters apart the U activation energy. The values of U for SiO2 and UO2, are considerably lower than the Us sublimation energies. Sputtering proceeds without threshold of Se.
Green synthesis of zinc oxide nanostructure using Azadirachta Indica leaf extract and its structural and microstructural study
Authors: Barman Kanailal , Chakraborty Pinaki , Samanta Pijus K
Published: January 2021

A green synthesis method using Azadirachta Indica leaf extract has been used to synthesized ZnO nanostructures. TEM image confirmed the formation of nanoparticles of size in the range of ∼50–100 nm. The stochiometry was also confirmed from the EDX spectroscopy. The structural analysis of the synthesized material was performed using the x-ray diffraction (XRD) data. The ZnO nanocrystals exhibit wurtzite unit cell structure as revealed from the XRD pattern. The calculation of lattice parameters shows that the distortion in the structure is very small. The material is highly crystalline with crystallite size of 20.05 nm and microstrain of 5.926 × 10−4. In this context crystallinity index is also calculated. The growth of the crystal is anisotropic as observed from the intensity of the diffraction and was quantified through the parameter degree of orientation. The synthesized ZnO nanostructure has large specific surface area. Other crystal parameters like Zn–O bond length, u-parameter, crystal volume were also calculated form the XRD pattern and show the structural perfection of the grown nanocrystal with a good figure of merit. Raman-shift measurements showed the existence of various phonon vibrational modes of the ZnO lattice. The material being synthesized by green approach is non-toxic in nature and may have potential applications in nanomaterials based medicinal and therapeutic applications.
Ground state of ultracold atoms in a hexagonal ring lattice with synthetic magnetic field
Authors: Meng Hong-Juan , Wang Wen-Yuan , Shi Yu-Ren
Published: January 2021

Ultracold atoms with an artificial gauge field provide a powerful platform for studying physical problems in various fields. We investigate the ground state of ultracold atoms in a hexagonal ring lattice with a synthetic magnetic field. The system undergoes a quantum phase transition characterized by degenerate and nondegenerate ground states. The phase transition depends on the atomic interaction and magnetic flux. With the quantum phase transition, a very interesting quantum odd–even parity effect emerges. The parity effects depend on a repulsive or attractive atomic interaction regime.
Minimum variance control of chaos in a hyperchaotic memristor based oscillator using online particle swarm optimization
Authors: Setoudeh Farbod , Khaki Sedigh Ali
Published: January 2021

This paper introduces a new hyperchaotic oscillator base on a new boundary-restricted Hewlett-Packard memristor model. Firstly, the complex system is designed based on a memristor-based hyperchaotic real system, and its properties are analyzed by means of Lyapunov exponents, Lyapunov dimension and phase portraits diagrams. Secondly, a simple feedback control based on the minimum variance control technique is designed to stabilize the hyperchaotic oscillator system, which is one of the new developed approaches for controlling the chaos in high-dimensional hyperchaotic systems. In this method, the time series variance is considered for designing and calculating the state feedback control gain. Furthermore, the state feedback control is designed so that to minimize the variance as a cost function, followed by developing an online optimization technique using the particle swarm optimization method in order to calculate the state feedback control based on the minimum variance strategy. Then, the application of this method is examined on a hyperchaotic memristor-based oscillator. Finally, the sensitivity of the proposed method is evaluated in different initial conditions that greatly influence the hyperchaotic dynamics. Considering that the optimization is online, simulation results show highly good effectiveness of the presented technique in controlling the chaos in high-dimensional hyperchaotic oscillators
Influence of direct Urca on the r-mode spin down features of newborn neutron star pulsars
Authors: Routray T R , Pattnaik S P , Gonzalez-Boquera C , Viñas X , Centelles M , Behera B
Published: January 2021

We perform a study on the time duration, final frequency, and exit temperature of the r-mode instability in newborn neutron stars of normal fluid composition under the assumption that the r-mode is the dominating spin-down mechanism. It is found that these spin-down features will vary widely depending on the star mass when direct Urca becomes operative. The occurrence of direct Urca is decided from the stiffness of the symmetry energy of the underlying equation of state, which is still uncertain. The change in the spin-down features in stars of different masses has been studied by computing the magnitude of the bulk viscosity due to the extent of direct Urca coverage in the core. The range for the variation of the symmetry energy stiffness, characterized by the slope parameter L, is decided from the tidal deformability data of the GW170817 event and the maximum mass constraint. The study is done by applying a family of equation of states obtained with the finite range simple effective interaction, constrained at low and intermediate densities by nuclear data and the flow analysis in heavy-ion collisions and at high densities by causality.
Elastic, mechanical, anisotropic, optical and magnetic properties of V2NiSb Heusler alloy
Authors: Güler M , Güler E , Uğur Ş , Uğur G , Charifi Z , Baaziz H
Published: January 2021

We have addressed the several unpublished elastic, mechanical, optical, anisotropic and magnetic properties of V2NiSb inverse Heusler alloy through the density functional theory (DFT) framework. Calculated elastic constants indicate mechanical stability and ductile mechanical character of the alloy. The alloy has high elastic anisotropy. Some optical properties like dielectric function, absorption, reflectance, optical conductivity, etc were also surveyed. According to the obtained results, V2NiSb is a good absorber and high refractive index material in the ultraviolet (UV) region. The magnetic results of the alloy signify typical ferromagnetism with 0.8 μ

B
total magnetic moment and compares well former findings. Our results may further shed light on the possible experimental researches of V2NiSb alloys for practical applications.
Is the atomic metal vapor a dielectric state?
Authors: Khomkin A L , Shumikhin A S
Published: January 2021

We propose a simple method for calculating the metal vapor conductivity at the critical point and near-critical isotherms This method is based on the hypothesis of an electron jellium’s existence as an origin of the conduction band in metal vapor’s gaseous phase. The hypothesis was suggested in our previous works, mentioned further in this article. Satisfactory agreement with the experimental data for alkali metals (Cs, Rb) allows us to conclude that, at the critical point and its vicinity, the atomic metal vapors should be considered as a gaseous metal, that is not a dielectric state of matter.
Development of a perceptually uniform physical scale for visual assessment of specular gloss
Authors: Mohammadalizadeh Ali , Mirjalili Fereshteh , Ameri Farhad , Moradian Siamak , Ansari Keivan , Safi Mahdi
Published: January 2021

Measuring gloss, visually or instrumentally, has been a challenge in many manufacturing and service industries. However, there exists no standardized method for visual evaluation of equidistance specular gloss. This study aimed to design and prepare a psychometric visually equispaced specular gloss scale for the visual measurement of gloss or any other geometric appearance attribute. To this end, a series of lithographically printed black papers, with different levels of gloss from low to high, were prepared to constitute a visually uniform specular gloss scale. Fourteen observers visually quantified the scale in a unidirectional illumination at three different geometries. Analyzing the results shows that the 60° geometry can quantify the equivalent specular gloss efficiently. A uniform specular gloss scale was prepared by assessing the prepared scale visually under the unidirectional illumination at the 60° geometry. Such a visually uniform specular gloss scale could be employed to develop a standard visual evaluation method of specular gloss in all related industries.
Theoretical investigation of a single vapor bubble during Al2O3/H2O nanofluids in power-law fluid affected by a variable surface tension
Authors: Abu-Nab A K , Selima E S , Morad Adel M
Published: January 2021

This article analyzes the growth of the vapor bubble in a novel model of power-law nanofluids (Al2O3/H2O) under a new effect of variable surface tension. The governing equations of the rising vapor bubble flow model are formulated and converted to a single equation describing the bubble dynamics behavior. By employing the model of Plesset and Zwick method, we investigate a new model of equations within power-law nanofluids to examine the effect of different physical parameters such as initial superheating liquid, critical bubble radius, and thermal diffusivity on the vapor bubble formation. Furthermore, the effects of surface tension behavior with the initial bubble radius, time, and initial rate of bubble radius are examined. It is found that the growth of the vapor bubble radius increases with the increase of initial superheating liquid, critical bubble radius, and thermal diffusivity. In addition, the connection between shear stress and shear rate is analyzed in detail. Using appropriate values for the physical parameters, the behavior of solutions of the vapor bubble is discussed. Based on the conducted simulation analysis, the behavior of the solutions is found to be more accurate than those in the previous studies. Besides, the obtained results demonstrate that the vapor bubble in power-law nanofluids grows slower than in pure water.
High-order breather, M-kink lump and semi-rational solutions of potential Kadomtsev–Petviashvili equation
Authors: Cao Yulei , Cheng Yi , He Jingsong , Chen Yiren
Published: January 2021

N-kink soliton and high-order synchronized breather solutions for potential Kadomtsev–Petviashvili equation are derived by means of the Hirota bilinear method, and the limit process of high-order synchronized breathers are shown. Furthermore, M-lump solutions are also presented by taking the long wave limit. Additionally, a family of semi-rational solutions with elastic collision are generated by taking a long-wave limit of only a part of exponential functions, their interaction behaviors are shown by three-dimensional plots and contour plots.
A 795 nm gain coupled distributed feedback semiconductor laser based on tilted waveguides*
Authors: Ma De-Zheng , Chen Yong-Yi , Lei Yu-Xin , Jia Peng , Gao Feng , Zeng Yu-Gang , Liang Lei , Song Yue , Ruan Chun-Kao , Liu Xia , Qin Li , Ning Yong-Qiang , Wang Li-Jun
Published: January 2021

The 795 nm distributed feedback lasers have great application in pumping the Rb D1 transition. In this paper, in order to realize specific 795 nm lasing, we designed tilted ridge distributed feedback lasers based on purely gain coupled effect induced by periodic current injection windows through changing the angle of the tilted ridge. The fabricated devices were cleaved into 2 mm-cavity-length, including 5 tilted angles. The peak output powers of all devices were above 30 mW. Single longitudinal mode lasing was realized in all tilted Fabry–Perot cavities using periodic current injection windows, with side mode suppression ratio over 30 dB. The total wavelength range covered 8.656 nm at 20 °C. It was disclosed theoretically and experimentally that the output powers, threshold currents, and central wavelengths of the tilted ridge purely gain coupled DFB lasers were relevant to the tilted angles. The results will be instructive for future design of DFB laser arrays with different central wavelengths.
Ultra-low Young’s modulus and high super-exchange interactions in monolayer CrN: A promising candidate for flexible spintronic applications*
Authors: Song Yang , Zhang Yan-Fang , Pan Jinbo , Du Shixuan
Published: January 2021

Monolayer CrN has been predicted to be half-metallic ferromagnet with high Curie temperature. Due to bulk CrN’s biocompatibility, the monolayer is a promising candidate for bio-related devices. Here, using first-principles calculations based on density functional theory, we find that the formation energy of the bulk CrN stacking from layers with square lattice is only 68 meV/atom above the convex hull, suggesting a great potential to fabricate the monolayer CrN in a square lattice by using molecular beam epitaxy method. The monolayer CrN is then proved to be a soft material with an ultra-low Young’s modulus and can sustain very large strains. Moreover, the analysis of the projected density of states demonstrates that the ferromagnetic half-metallicity originates from the splitting of Cr-d orbitals in the CrN square crystal field, the bonding interaction between Cr–N, and that between Cr–Cr atoms. It is worth noting that the super-exchange interaction is much larger than the direct-exchange interaction and contributes to the ultra-high Curie temperature, which is obtained from Monte Carlo simulations based on Heisenberg model. Our findings suggest that the monolayer CrN can be an indispensable candidate for nanoscale flexible spintronic applications with good biocompatibility and is considerable appealing to be realized in experiment.
Accurate hemodynamic response estimation by removal of stimulus-evoked superficial response in fNIRS signals
Authors: Galli Alessandra , Brigadoi Sabrina , Giorgi Giada , Sparacino Giovanni , Narduzzi Claudio
Published: January 2021

Objective. We address the problem of hemodynamic response (HR) estimation when task-evoked extra-cerebral components are present in functional near-infrared spectroscopy (fNIRS) signals. These components might bias the HR estimation; therefore, careful and accurate denoising of data is needed. Approach. We propose a dictionary-based algorithm to process each single event-related segment of the acquired signal for both long separation (LS) and short separation (SS) channels. Stimulus-evoked components and physiological noise are modeled by means of two distinct waveform dictionaries. For each segment, after removal of the physiological noise component in each channel, a template is employed to estimate stimulus-evoked responses in both channels. Then, the estimate from the SS channel is employed to correct the evoked superficial response and refine the HR estimate from the LS channel. Main results. Analysis of simulated, semi-simulated and real data shows that, by averaging single-segment estimates over multiple trials in an experiment, reliable results and improved accuracy compared to other methods can be obtained. The average estimation error of the proposed method for the semi-simulated data set is 34% for oxy-hemoglobin (HbO) and 78% for deoxy-hemoglobin (HbR), considering 40 trials. The proposed method outperforms the results of the methods proposed in the literature. While still far from the possibility of single-trial HR estimation, a significant reduction in the number of averaged trials can also be obtained. Significance. This work proves that dedicated dictionaries can be successfully employed to model all different components of fNIRS signals. We demonstrate the effectiveness of a specifically designed algorithm structure in dealing with a complex denoising problem, enhancing the possibilities of fNIRS-based HR analysis.
Two-parameter modified rigid rotor radial equilibrium model for field-reversed configurations
Authors: Ma H.J. , Xie H.S. , Bai Y.K. , Cheng S.K. , Deng B.H. , Tuszewski M. , Li Y. , Zhao H.Y. , Chen B. , Liu J.Y.
Published: January 2021

A new equilibrium pressure profile is proposed that extends the rigid rotor (RR) model with a simple unified expression P = P(ψ; β
s, α, σ) for both inside and outside the separatrix. A new method is described for solving the field-reversed configuration (FRC) one-dimensional (1D) equilibrium with only two parameters. The radial normalized FRC equilibrium profiles for pressure, magnetic field, and current density can be uniquely determined by the dimensionless parameters of

β

s

≡

P

s

/

B

e

2

/
2

μ

0

and δ
s ≡ L
ps/R
s. This modified rigid rotor (MRR) model has sufficient flexibility to accommodate narrow scrape-off layer (SOL) widths and hollow current density profiles, and can be used to fit experimental measurements. A database of 1D plasma equilibria in the (β
s, δ
s) space is provided for the convenience of real-time approximate FRC equilibrium reconstruction. The detailed one-dimensional (1D) characteristics of the equilibrium models are investigated analytically and numerically. The 1D results from the MRR models are also validated using two-dimensional (2D) Grad–Shafranov (G–S) equilibrium solutions.
Towards a maintainable and high efficiency neutral beam system for future fusion reactors
Authors: Simonin A. , Blondel C. , Chaibi W. , Dechelle C. , Drag C. , Villedieu E.
Published: January 2021

Achievement of an economic fusion reactor imposes a high level of unprecedented requirements for neutral beam systems; the first one is the nuclear safety constraints which impose a prerequisite on the ease of access of all injector components to provide a preventive (and curative) maintenance by remote handling while maintaining reactor operation. In addition, the challenge is to develop high-power injectors with very high wall-plug efficiency (above 60%) that are able to operate in stable conditions over several months. There is a significant gap to bridge with respect to the present neutral beam systems, which are characterized by a low efficiency and by complex and long maintenance operations. Evidence that this injector concept does not offer adaptations to cope with the reactor requirements makes it clear that a new concept has to be addressed. An injector concept with modular sources at ground voltage is proposed. The concept makes remote maintenance of the injector components easier, where each source module can be replaced by a new one without breaking the vacuum and affecting injector conditioning. With the grounded and modular ion source, photoneutralization associated with energy recovery appears to be the best route capable of attaining the reactor requirements. This concept of a maintainable neutral beam system would provide a high heating power with a wall-plug efficiency above 70% and unprecedented features such as the capacity of producing temporal and spatial modulation of the beam power for a better control of the plasma stability. Up to now, photoneutralization feasibility studies already carried out on reduced-scale prototypes have not highlighted any showstoppers. Continuation of research and development in the years to come can pave the way towards the achievement of a first full-scale high-power cavity in the 1 MW range, and the realization of a multi-amperes (∼10 A) thin blade-like D− beam.
Quasi-linear theory of forced magnetic reconnection for the transition from the linear to the Rutherford regime
Authors: Huang Wenlong , Zhu Ping
Published: January 2021

Using the in-viscid two-field reduced magneto-hydrodynamic (MHD) model, a new analytical theory is developed to unify the Hahm–Kulsrud–Taylor (HKT) linear solution and the Rutherford quasi-linear regime. Adopting a quasi-linear approach, we obtain a closed system of equations for plasma response in the Taylor problem. An integral form of an analytical solution is obtained for the forced magnetic reconnection, uniformly valid throughout the entire regimes from the HKT linear solution to the Rutherford quasi-linear solution. In particular, the quasi-linear effect can be described by a single coefficient

K

s

∝

S

8
/
5

ψ

c

2

, where

S
=

τ

R

τ

A

and ψ
c are the Lundquist number and amplitude of external magnetic perturbation, respectively. The HKT linear solution for the response can be recovered when the index K
s → 0. On the other hand, the quasi-linear effect plays a key role in the island growth when K
s ∼ 1. Our new analytical solution has also been compared with reduced MHD simulations with agreement.
Divertor power load predictions based on machine learning
Authors: Brenzke M. , Wiesen S. , Bernert M. , Coster D. , Jitsev J. , Liang Y. , von Toussaint U. , ASDEX Upgrade Team  , EUROfusion MST1 Team
Published: January 2021

Machine learning based data-driven approaches to thermal load prediction on the divertor targets of ASDEX upgrade (AUG) are presented. After selecting time averaged data from almost six years of operation of AUG and applying basic physics-motivated cuts to the data we find that we are able to train machine learning models to predict a scalar quantifying the steady state thermal loads on the outer divertor target given scalar operational parameters. With both random forest and neural network based models we manage to achieve decent agreement between the model predictions and the observed values from experiments. Furthermore, we investigate the dependencies of the models and observe that the models manage to extract trends expected from previous physics analyses.
Fermionic quantum cellular automata and generalized matrix-product unitaries
Authors: Piroli Lorenzo , Turzillo Alex , Shukla Sujeet K , Cirac J Ignacio
Published: January 2021

In this paper, we study matrix-product unitary operators (MPUs) for fermionic one-dimensional chains. In stark contrast to the case of 1D qudit systems, we show that (i) fermionic MPUs (fMPUs) do not necessarily feature a strict causal cone and (ii) not all fermionic quantum cellular automata (QCA) can be represented as fMPUs. We then introduce a natural generalization of the latter, obtained by allowing for an additional operator acting on their auxiliary space. We characterize a family of such generalized MPUs that are locality-preserving, and show that, up to appending inert ancillary fermionic degrees of freedom, any representative of this family is a fermionic QCA (fQCA) and vice versa. Finally, we prove an index theorem for generalized MPUs, recovering the recently derived classification of fQCA in one dimension. As a technical tool for our analysis, we also introduce a graded canonical form for fermionic matrix product states, proving its uniqueness up to similarity transformations.
A Review on the Energy prospects of Indian Remote Islands and Preliminary assessment of Marine Current Energy Potential
Authors: Vyshnavi P. , Samad A. , Venkatesan N. , Avital E.J.
Published: January 2021

The islands in the Indian Ocean as other remote islands are often challenged to meet their energy needs, and constantly getting electricity from the mainland is expensive. In this article, the present scenario and future prospects of the energy sources for all the Indian islands are discussed. Data collected from different buoys of INCOIS are analysed, and a location near Minicoy has been chosen for further study. This paper also provides the preliminary analysis of marine current energy feasibility in that location.
Grid integration of Photovoltaic System Interfaced with Artificial Intelligence based Modified Universal Power Quality conditioning system
Authors: Marshall Arockia Dass P , Peer Fathima A
Published: January 2021

Unified Power Quality Compensators (UPQC) in load side utility system is not able to fully suppress harmonies in power grid and distortion in the interface system. To enhance the operation of the UPQC, a Fuzzy based Modified Universal power quality conditioning system (Fuzzy-MUPQCS) is developed. Modified Universal power quality conditioning system (MUPQCS) is a combination of two active filters in series and one active filter in shunt. A 3φ voltage source inverter is also used to maintain a common DC link capacitor voltage through Photo voltaic (PV) system connected to a utility grid. Highest Power Point Tracking (HPPT) algorithm is mainly used to pull out the maximum amount of power in the PV system. In this paper, Proportional integral controller based MUPQCS (PI- MUPQCS) and Fuzzy-MUPQCS are used to analyse the load voltage and load current distortion, THD analysis, power factor measurement, grid voltage and grid current distortion in the three phase system under nonlinear load conditions. The execution of the MUPQCS based 3φ system and the controllers are simulated using Matlab /Simulink model.
Peak Ground Acceleration Analysis using Past Earthquake Data
Authors: Elizabeth Philip Swetha , Helen Santhi M.
Published: January 2021

Peak Ground Acceleration (PGA) is one of the important parameters in the design of seismic resistant structures. In order to predict the value of PGA for a particular place, the past seismic history of that place in terms of data sets is required. The seismic data analysis of regions or nations becomes mandatory due to the frequent occurrence of earthquakes worldwide. This paper presents a study to predict peak ground acceleration of Maharashtra, India by using Excel and MATLAB tools. The available parameters used for the prediction are PGA, epicentral distance, depth and moment magnitude from the year 1912 to 2009. Both the tools have good fit in the prediction of PGA of Maharashtra (R2 >0.9); however Excel may be preferred because of its simplicity and flexibility in handling the data sets.
Comparative Study on the Dynamic Analysis of Blast Loaded Concrete and Steel Structure
Authors: Moniksh Kumar S , Vasugi V , Elavenil S
Published: January 2021

The terrorist attack on buildings or in its surrounding has increased steadily in recent years. Usually, the blast might occur in the ground level thus columns in ground-level undergo impact loading. Since steel and composite type of columns are used nowadays, the nonlinear dynamic analysis of blast loading in such columns has become highly important. This helps to understand the impact of explosions on columns. In this study, RC column, steel and composite column with equal height are designed for the same load-carrying capacity and Finite Element Modeling using ABAQUS. Time History Method is used to analyze the columns. This study aims to simulate and compare the non-linear dynamic analysis of blast loaded concrete and steel structures. The examination of the result exposes the vulnerability in the steel column and the effectiveness of the composite column. RDX of charge weight 100 kg and standoff distance of 1 meter is considered for analysis.
Prediction of self-healing characteristics of GGBS admixed concrete using Artificial Neural Network
Authors: Chaitanya M , Manikandan P , Prem Kumar V , Elavenil S , Vasugi V
Published: January 2021

Concrete has become a significant part of our lives; the utilization of concrete is increasing at a high rate. One of the most constituents of concrete is Ordinary Portland Cement (OPC). The manufacturing process of OPC leads to the emission of huge amounts of CO2. Thus the researchers have started finding alternatives for the replacement of cement. The primary objective of this paper is to investigate the behavior of M40 grade concrete when partially replaced with Ground Granulated Blast Furnace slag (GGBS) at the same time using SAP and study the self-healing behavior of partially replacement concrete. In the self-healing process, the healing agent absorbs the moisture content within the atmosphere to heal the crack. Superabsorbent Polymers (SAPs) are materials that will absorb and retain an oversized volume of water and aqueous solutions. In this investigation, 51 samples of cubes are prepared for compressive strength test and self-healing test, the specimen is pre-cracked on the 28th day for healing purposes. Further, this article aims to predict the self-healing characteristics of the M40 grade of concrete using Neural Networks by incorporating different proportions of GGBS (0%, 40% and 60%) and SAPs. The predicted results obtained from the ANN model were in good agreement with experimental values.
Investigation on performance of water ion modified cement matrix
Authors: Thenua Kanuj , Shanmugasundaram M , Karthiyaini S
Published: January 2021

The water used in preparation of cement composite is going to be altered through magnetization. When the water is kept in magnetic field the additional hardness elements i.e., Ca, Mg and Fe get separated from water. But this separation cannot be done through normal magnetic field. Hence high electromagnetic diffuser or high-end magnets are needed. In this study Neodymium (Nd) - N52 magnets were used which has an atomic number 60. The water kept under the magnetic field for various time periods. The strength variation and development will be studied for mortar on various edges.
Development of Product Assembly Instructional Video for training purpose
Authors: BalaSeshan P , Janardhan Reddy Dr K
Published: January 2021

This work is focused on the development of effective Product Assembly Instructional Videos. Product assembly instructional video is an important element for training, and boost the skills of employees by laying virtual information of any complex assembly. The instructional video is aimed to train employees on “How the product is assembled” with detailed steps to be followed during assembly and with instructional voice-over n a rendered video. It is found from the literature that traditional training often consumes more time and resource for any organization and frequent changes in manpower makes it more difficult for them to spend adequate time to train. So, the instructional videos are helpful to overcome such problems. The method used in this research paper is to develop a framework for product assembly instructional videos. The research s extended via a case study where n these videos are used for training and discuss with the practitioners regarding how they review this model. This paper concludes with a framework for product assembly instructional videos and describing various factors to consider in the creation of industrial training videos. The work also used various software which includes CAD tools, voice recording, impending, and video editing tools to create a training video manual.
Intelligent Obstacle Avoiding AGV Using Vector Field Histogram and Supervisory Control
Authors: Bolbhat S. S. , Bhosale A. S. , Sakthivel G. , Saravanakumar D. , Sivakumar R. , Lakshmipathi J
Published: January 2021

Automated Guided Vehicles are used to help the process of carrying materials from one place to another. AGVs are widely used in the materials handling process in different industries hence, the reasoning behind their extremely wide usage in industries such as Automotive, manufacturing, Medical, etc. This research deals with the obstacle avoidance of Automated Guided Vehicles (AGV). This paper propose an algorithm that helps to build obstacle-free trajectories for AGV that leave the original track and again get back to the original track by avoiding the obstacle. The new path also have to act according to the dynamic & kinematic constraints of the AGV. The proposed method will be validated using simulations.
Implementation of Two-Dimensional (2D) Discrete Cosine Transform (DCT) using Reversible Gates
Authors: Aravindh Sathesh , Sakthivel S M
Published: January 2021

This research work presents the application-specific integrated circuit (ASIC) implementation of one dimensional (1 × 8) and two dimensional (8 × 8) discrete cosine transform using the reversible logic gates. During the DCT implementation, the integer DCT method of realization is adopted, thereby eliminating the occurrence of floating-point operations in the data path architecture. Thus, the integer mode of DCT realization using reversible logic gates in the proposed DCT architecture improves the delay, power and area of the 1D and 2D DCT data path structure when compared with the normal real DCT implementation. The proposed methodology of DCT implementation includes the construction of full adder and full subtractor using reversible gates and then extended for the realization of the DCT butterfly structure. Especially in this research method, Peres reversible gate is used for the implementation of full-adder and Thapliyal Ranganathan (TR) gate for the implementation of full subtractor, respectively. Thus, the 1D and 2D DCT implementation using reversible logic gates in 180nm technology nodes consume an overall area of 55504.311 sq.µm and 1122324.044 sq.µm respectively.
Low power SRAM using Adiabatic Logic
Authors: Anudeep Varma C , Sasipriya P
Published: January 2021

In this paper the design of low power SRAM has been presented. SRAM memory cell has been realized using adiabatic logic to achieve low power operation. Adiabatic SRAM has been realized using two methods such as i) gradual charging and discharging of bit-line during writing mode and ii) utilizing control transistor based adiabatic circuit i.e., Two Phase Adiabatic Dynamic Logic (2PADL) circuit for the design of memory cell. Furthermore, energy recovery of word line and bit line charge stored in the interconnect capacitances has been realized for the benefit of energy savings. Charge recovery circuits based on 2PADL has been employed in the proposed SRAM memory core to achieve energy recovery. SRAM memory array of (4×4) has been designed as a test circuit. All the circuits are implemented using 180nm CMOS technology and simulations are carried out using Cadence® Virtuoso tool. Simulation results prove that the proposed memory cell has significant amount of energy savings when compared to the conventional static CMOS SRAM cell.