bluuebunny/crossref_metadata_2025 huggingface dataset:
Parametric resonance of bi-directional axial loads shallow arch microresonators
Authors: Najar Fehmi , Ouakad Hassen M , Ramini Abdallah , Alcheikh Nouha , Younis Mohammad I
Published: March 2022

In this work, we investigate analytically and experimentally parametric resonances of an in-plane clamped-guided shallow arch microresonator. The arch is connected to a T-shaped moveable mass, which is sandwiched between two electrodes to electrostatically activate the device and to offer bi-directional axial loads option. The device is tested under primary and secondary parametric resonances. In addition, an analytical model is presented taking into account the initial rise of the microbeam and the sliding motion at the guided side. The static and free vibration problems are solved using the Differential Quadrature Method, and the dynamic response is simulated using an assumed mode Galerkin approximation. The theoretical results of the static and dynamic behavior of the device are compared to experimental data showing good agreement. Moreover, we demonstrate the use of parametric excitation to significantly amplify the axial motion. It is found that the second parametric resonance, corresponding to the fundamental mode of the arched microbeam, has a higher amplitude than the principal parametric case, due to the initial curvature of the beam. Thus, the proposed device can be a promising candidate for variety of sensing applications.
Plasma asymmetry and electron and ion energy distribution function in capacitive discharges excited by tailored waveforms
Authors: Sharma Sarveshwar , Sirse Nishant , Kuley Animesh , Turner Miles M
Published: March 2022

Using a particle-in-cell simulation technique, we investigate the plasma and ionization asymmetry, higher harmonics generation, and electron and ion energy distribution function (IEDF) in capacitive discharges excited by tailored waveforms. At a base frequency of 13.56 MHz, three different waveforms, namely sinusoidal, sawtooth, and square, are applied for a constant current density amplitude of 50 A m−2 and gas pressure of 5 mTorr. The simulation results show that the square waveform produces the highest plasma density in the discharge, whereas maximum asymmetry is observed for plasma excited by the sawtooth-like waveform. Both square and sawtooth waveforms generate multiple beams of high-energy electrons from near to the expanding phase of the sheath edge and high-frequency modulations up to 100 MHz on the instantaneous sheath position. The electron energy distribution function depicts three electron temperature and highly elevated tail-end electrons for the square waveform in comparison to the sinusoidal and sawtooth waveform. The IEDF is bimodal at both the powered and grounded electrodes with a large asymmetry and narrow-type distribution in the case of the sawtooth-like waveform. These results suggest that the choice of waveform is highly critical for achieving maximum asymmetry and plasma density simultaneously in capacitive discharges.
A new kaonic helium measurement in gas by SIDDHARTINO at the DAΦNE collider*
Authors: Sirghi D , Sirghi F , Sgaramella F , Bazzi M , Bosnar D , Bragadireanu M , Carminati M , Cargnelli M , Clozza A , Deda G , De Paolis L , Del Grande R , Fabbietti L , Fiorini C , Guaraldo C , Iliescu M , Iwasaki M , Levi Sandri P , Marton J , Miliucci M , Moskal P , Napolitano F , Niedźwiecki S , Piscicchia K , Scordo A , Shi H , Skurzok M , Silarski M , Spallone A , Tüchler M , Vazquez Doce O , Zmeskal J , Curceanu C
Published: March 2022

The SIDDHARTINO experiment at the DAΦNE collider of INFN-LNF, the pilot run for the SIDDHARTA-2 experiment which aims to perform the measurement of kaonic deuterium transitions to the fundamental level, has successfully been concluded in July 2021. The paper reports the main results of this run, including the optimization of various components of the apparatus, among which the degrader needed to maximize the fraction of kaons stopped inside the target, through measurements of kaonic helium transitions to the 2p level. The obtained shift and width values are ε
2p = E
exp − E
e.m = 0.2 ± 2.5(stat) ± 2.0(syst) eV and Γ2p = 8 ± 10 eV (stat), respectively. This new measurement of the shift, in particular, represents the most precise one for a gaseous target and is expected to contribute to a better understanding of the kaon–nuclei interaction at low energy. The results obtained in this pilot run, combined with the foreseen additional veto systems and projected for the total 48 SDD arrays of the SIDDHARTA-2 final setup, represent a solid starting point for the successful measurement of the kaonic deuterium 2p → 1s transition, main goal of the experiment.
A transmission electron microscopy study of low-strain epitaxial BaTiO3 grown onto NdScO3
Authors: Denneulin T , Everhardt A S
Published: March 2022

Ferroelectric materials exhibit a strong coupling between strain and electrical polarization. In epitaxial thin films, the strain induced by the substrate can be used to tune the domain structure. Substrates of rare-earth scandates are sometimes selected for the growth of ferroelectric oxides because of their close lattice match, which allows the growth of low-strain dislocation-free layers. Transmission electron microscopy (TEM) is a frequently used technique for investigating ferroelectric domains at the nanometer-scale. However, it requires to thin the specimen down to electron transparency, which can modify the strain and the electrostatic boundary conditions. Here, we have investigated a 320 nm thick epitaxial layer of BaTiO3 grown onto an orthorhombic substrate of NdScO3 with interfacial lattice strains of −0.45% and −0.05% along the two in-plane directions. We show that the domain structure of the layer can be significantly altered by TEM sample preparation depending on the orientation and the geometry of the lamella. In the as-grown state, the sample shows an anisotropic a/c ferroelastic domain pattern in the direction of largest strain. If a TEM lamella is cut perpendicular to this direction so that strain is released, a new domain pattern is obtained, which consists of bundles of thin horizontal stripes parallel to the interfaces. These stripe domains correspond to a sheared crystalline structure (orthorhombic or monoclinic) with inclined polarization vectors and with at least four variants of polarization. The stripe domains are distributed in triangular-shaped 180° domains where the average polarization is parallel to the growth direction. The influence of external electric fields on this domain structure was investigated using in situ biasing and dark-field imaging in TEM.
SOiCI and iCISO: combining iterative configuration interaction with spin–orbit coupling in two ways
Authors: Zhang Ning , Xiao Yunlong , Liu Wenjian
Published: March 2022

The near-exact iCIPT2 approach for strongly correlated systems of electrons, which stems from the combination of iterative configuration interaction (iCI, an exact solver of full CI) with configuration selection for static correlation and second-order perturbation theory (PT2) for dynamic correlation, is extended to the relativistic domain. In the spirit of spin separation, relativistic effects are treated in two steps: scalar relativity is treated by the infinite-order, spin-free part of the exact two-component (X2C) relativistic Hamiltonian, whereas spin–orbit coupling (SOC) is treated by the first-order, Douglas–Kroll–Hess-like SOC operator derived from the same X2C Hamiltonian. Two possible combinations of iCIPT2 with SOC are considered, i.e., SOiCI and iCISO. The former treats SOC and electron correlation on an equal footing, whereas the latter treats SOC in the spirit of state interaction, by constructing and diagonalizing an effective spin–orbit Hamiltonian matrix in a small number of correlated scalar states. Both double group and time reversal symmetries are incorporated to simplify the computation. Pilot applications reveal that SOiCI is very accurate for the spin–orbit splitting (SOS) of heavy atoms, whereas the computationally very cheap iCISO can safely be applied to the SOS of light atoms and even of systems containing heavy atoms when SOC is largely quenched by ligand fields.
Direct estimation of gas holdup in gas–liquid bubble column reactors using ultrasonic transmission tomography and artificial neural processing
Authors: Hu Jingyi , Li Nan , Wang Lina , Yang Peng , Yang Yunjie , Quan Yihong
Published: March 2022

Ultrasonic transmission tomography is an effective non-intrusive method for detecting gas–liquid two-phase flow patterns. A specific interest is the many processes whose reaction utilizes a bubble column, where the fast estimation of cross-sectional gas-holdup ratio is important for monitoring and control. In this study reference indirect image-based estimates were obtained from reconstructed tomographic data. Direct (non-image) estimation of the gas holdup ratio was also obtained using trained neural processing networks. Two forms were trialled: a generalized regression neural network (GRNN); and a long short-term memory (LSTM) network. Comparison trials were carried out for single-bubble, dual-bubble, circulation and laminar flows. Relative cross-sectional gas holdup error was selected for evaluation. For the image-based indirect trials the Tikhonov regularization algorithm had the lowest error range: 2.15%–15.64%. For direct methods the LSTM network had the lowest error range: 0.41%–9.63%, giving better performance than the image-based methods. The experimental data were used to verify the effectiveness of the network. The root-mean-square error of the test metrics for GRNN and LSTM network were 6.4260 and 5.4282, respectively, indicating that LSTM network has higher performance in processing the data in this paper.
ZnO nanoparticles embedded silk fibroin—a piezoelectric composite for nanogenerator applications
Authors: Sarkar Lisa , Sushma Mudigunda V , Yalagala Bhavani Prasad , Rengan Aravind Kumar , Singh Shiv Govind , Vanjari Siva Rama Krishna
Published: March 2022

This paper demonstrates a flexible nanogenerator (NG) using Silk-Zinc Oxide (ZnO) composite by exploiting the inherent piezoelectric properties of silk and ZnO. A direct precipitation method was employed to synthesize Zinc Oxide nanoparticles (NPs). Silk-ZnO composite film was then prepared by spin-coating the homogenous silk-ZnO solution. The composition and morphology of silk-ZnO composite were analyzed using various standard characterization procedures. The biocompatibility study of the composite film was also performed through cell viability testing. The utility of as prepared composites was demonstrated through the fabrication of piezoelectric nanogenerator. This hybrid nanogenerator was capable to generate a maximum open circuit voltage of 25 V (peak to peak value) in the bending state for a specific ZnO concentration. The output response of the nanogenerator exhibited a good correlation with the bending angle of the device. A peak outputpower density of 6.67 mW cm−3 was achieved from the nanogenerator. The fabricated prototype is efficient to light-up commercial red LEDs and to harvest energy from human body movement. The piezoelectric coefficient (d
33) of silk-ZnO composite film was also experimentally figured out.
Negative out-of-plane Poisson’s ratio of bilayer graphane
Authors: Ho Viet Hung , Ho Duc Tam , Nguyen Cao Thang , Kim Sung Youb
Published: March 2022

With its excellent mechanical and thermal properties, bilayer graphane is a promising material for realizing future nanoelectromechanical systems. In this study, we focus on the auxetic behavior of bilayer graphane under external loading along various directions through atomistic simulations. We numerically and theoretically reveal the mechanism of the auxeticity in terms of intrinsic interactions between carbon atoms by constructing bilayer graphane. Given that the origin of the auxeticity is intrinsic rather than extrinsic, the work provides a novel technique to control the dimensions of nanoscale bilayer graphane by simply changing the external conditions without the requirement of complex structural design of the material.
Improving the photoresponse performance of monolayer MoS2 photodetector via local flexoelectric effect
Authors: Feng Pu , Zhao Sixiang , Dang Congcong , He Sixian , Li Ming , Zhao Liancheng , Gao Liming
Published: March 2022

Strain engineering is an effective means of modulating the optical and electrical properties of two-dimensional materials. The flexoelectric effect caused by inhomogeneous strain exists in most dielectric materials, which breaks the limit of the materials’ non-centrosymmetric structure for piezoelectric effect. However, there is a lack of understanding of the impact on optoelectronic behaviour of monolayer MoS2 photodetector via local flexoelectric effect triggered by biaxial strain. In this paper, we develop a probe tip (Pt)-MoS2-Au asymmetric Schottky barrier photodetector based on conductive atomic force microscopy to investigate the impact of flexoelectric effect on the photoresponse performance. Consequently, when the probe force increases from 24 nN to 720 nN, the photocurrent, responsivity and detectivity increase 28.5 times, 29.6 times and 5.3 times at forward bias under 365 nm light illumination, respectively. These results indicate that local flexoelectric effect plays a critical role to improve the photoresponse performance of photodetector. Our approach suggests a new route to improve the performance of photodetectors by introducing local flexoelectric polarization field, offering the potential for the application of strain modulated photoelectric devices.
Excitation of Alfvén eigenmodes by fusion-born alpha-particles in D-3He plasmas on JET
Authors: Kiptily V G , Kazakov Ye O , Nocente M , Ongena J , Belli F , Dreval M , Craciunescu T , Eriksson J , Fitzgerald M , Giacomelli L , Goloborodko V , Iliasova M V , Khilkevitch E M , Rigamonti D , Sahlberg A , Salewski M , Shevelev A E , Garcia J , Oliver H J C , Sharapov S E , Stancar Z , Weisen H
Published: March 2022

Alfvén eigenmode (AE) instabilities driven by alpha-particles have been observed in D-3He fusion experiments on the Joint European Torus (JET) with the ITER-like wall. For the efficient generation of fusion alpha-particles from D-3He fusion reaction, the three-ion radio frequency scenario was used to accelerate the neutral beam injection 100 keV deuterons to higher energies in the core of mixed D-3He plasmas at high concentrations of 3He. A large variety of fast-ion driven magnetohydrodynamic modes were observed, including the elliptical Alfvén eigenmodes (EAEs) with mode numbers n = −1 and axisymmetric modes with n = 0 in the frequency range of EAEs. The simultaneous observation of these modes indicates the presence of rather strong alpha-particle population in the plasma with a ‘bump-on-tail’ shaped velocity distribution. Linear stability analysis and Fokker–Planck calculations support the observations. Experimental evidence of the AEs excitation by fusion-born alpha-particles in the D-3He plasma is provided by neutron and gamma-ray diagnostics as well as fast-ion loss measurements. We discuss an experimental proposal for the planned full-scale D-T plasma experiments on JET based on the physics insights gained from these experiments.
New phenomena in laser-assisted leptonic decays of the negatively charged boson W
−
Authors: Mouslih S , Jakha M , Dahiri I , Taj S , Manaut B , Siher E
Published: March 2022

The majority of studies and experiments performed at electron-positron colliders over the last two decades have focused on studying W and Z weak force-carrying bosons and accurately measuring all their properties, not only because they play an important role in establishing Standard Model theory and providing an accurate test of its predictions of particle interactions, but also because they are a unique tool for probing manifestations of the new physics beyond the standard model. Therefore, it would be particularly important to discuss some of the new phenomena and changes that can arise in these bosons when their decay occurs under an external electromagnetic field. In a recent paper, we investigated the laser effect on the final products of Z boson decay and found that laser had an unprecedented effect on branching ratios. In this work and within the standard Glashow-Weinberg-Salam model of electroweak interactions, we study theoretically the leptonic decay of the W
−-boson

(

W

−

→

ℓ

−

ν

¯

ℓ

)

in the presence of a circularly polarized electromagnetic field and we examine the laser effect, in terms of its field strength and frequency, on the leptonic decay rate and the phenomenon of multiphoton processes. The calculations are carried out using the exact relativistic wave functions of charged particles in an electromagnetic field. It was found that the laser significantly contributed to reducing the probability of W
−-boson decay. We show that the laser-assisted decay rate is equal to the laser-free one only when the famous Kroll-Watson sum rule is fulfilled. The notable effect of the laser on the leptonic decay rate was reasonably interpreted by the well-known quantum Zeno effect or by the opening of channels other than leptonic ones to decay. This work will pave the way for an upcoming one to study the hadronic decay of the W
−-boson and then explore the laser effect on its lifetime and branching ratios.
Vibrational resonance and bifurcation in a fractional order quintic system with distributed time delay
Authors: Ning Lijuan , Zhao Keya
Published: March 2022

In this paper, vibrational resonance and bifurcation phenomena are investigated in the fractional order quintic system with distributed time delay. The approximate theoretical expression for the response amplitude at low frequency is derived by using the method of fast and slow variable separation. In the presence of fractional order and distributed time delay, the vibrational resonance and bifurcation are explored in the single-well, double-well and triple-well potentials, respectively. It is found that the decay rate of the kernel function σ can cause bifurcation, which is closely related to the high frequency excitation amplitude F. It is worth noting that the range of

ω

r

2

in which resonance occurs twice, three and four times decreases with the increase of σ. Furthermore, appropriate values of the decay rate σ, fractional order α and high frequency excitation amplitude F will enable to improve the response amplitude Q. The high match of the numerical simulation and analytical results confirms the validity of the theoretical analysis.
Primordial black hole formation with full numerical relativity
Authors: de Jong Eloy , Aurrekoetxea Josu C. , Lim Eugene A.
Published: March 2022

We study the formation of black holes from subhorizon and superhorizon perturbations in a matter dominated universe with 3+1D numerical relativity simulations. We find that there are two primary mechanisms of formation depending on the initial perturbation's mass and geometry — via direct collapse of the initial overdensity and via post-collapse accretion of the ambient dark matter. In particular, for the latter case, the initial perturbation does not have to satisfy the hoop conjecture for a black hole to form. In both cases, the duration of the formation the process is around a Hubble time, and the initial mass of the black hole is M
BH ∼ 10-2
H
-1
M
Pl
2. Post formation, we find that the PBH undergoes rapid mass growth beyond the self-similar limit M
BH α H
-1, at least initially. We argue that this implies that most of the final mass of the PBH is accreted from its ambient surroundings post formation.
Constraining primordial black holes as dark matter using the global 21-cm signal with X-ray heating and excess radio background
Authors: Mittal Shikhar , Ray Anupam , Kulkarni Girish , Dasgupta Basudeb
Published: March 2022

Using the global 21-cm signal measurement by the EDGES collaboration, we derive constraints on the fraction of the dark matter that is in the form of primordial black holes (PBHs) with masses in the range 1015–1017 g. Improving upon previous analyses, we consider the effect of the X-ray heating of the intergalactic medium on these constraints, and also use the full shape of the 21-cm absorption feature in our inference. In order to account for the anomalously deep absorption amplitude, we also consider an excess radio background motivated by LWA1 and ARCADE2 observations. Because the heating rate induced by PBH evaporation evolves slowly, the data favour a scenario in which PBH-induced heating is accompanied by X-ray heating. Also, for the same reason, using the full measurement across the EDGES observation band yields much stronger constraints on PBHs than just the redshift of absorption. We find that 21-cm observations exclude f
PBH ≳ 10-9.7 at 95% CL for M
PBH = 1015 g. This limit weakens approximately as M
4
PBH towards higher masses, thus providing the strongest constraints on ultralight evaporating PBHs as dark matter over the entire mass range 1015–1017 g. Under the assumption of a simple spherical gravitational collapse based on the Press-Schechter formalism, we also derive bounds on the curvature power spectrum at extremely small scales (k ∼ 1015 Mpc-1). This highlights the usefulness of global 21-cm measurements, including non-detections, across wide frequency bands for probing exotic physical processes.
Quasi-linearization and stability analysis of some self-dual, dark equations and a new dynamical system
†
Authors: Blackmore Denis , Prytula Mykola M , Prykarpatski Anatolij K
Published: March 2022

We describe a class of self-dual dark nonlinear dynamical systems a priori allowing their quasi-linearization, whose integrability can be effectively studied by means of a geometrically based gradient-holonomic approach. A special case of the self-dual dynamical system, parametrically dependent on a functional variable is considered, and the related integrability condition is formulated. Using this integrability scheme, we study a new self-dual, dark nonlinear dynamical system on a smooth functional manifold, which models the interaction of atmospheric magneto-sonic Alfvén plasma waves. We prove that this dynamical system possesses a Lax representation that allows its full direct linearization and compatible Poisson structures. Moreover, for this self-dual nonlinear dynamical system we construct an infinite hierarchy of mutually commuting conservation laws and prove its complete integrability.
Effects of phosphorus doping on the physical properties of axion insulator candidate EuIn2As2
Authors: Pan Feihao , Tian Congkuan , Huang Jiale , Xu Daye , Wang Jinchen , Cheng Peng , Liu Juanjuan , Zhang Hongxia
Published: March 2022

We report an investigation on the single crystal growth, magnetic and transport properties of EuIn2(As1−x
P
x
)2 (0 ≤ x ≤ 1). The physical properties of axion insulator candidate EuIn2As2 can be effectively tuned by P-doping. With increasing x, the c-axis lattice parameter decreases linearly, the magnetic transition temperature gradually increases and ferromagnetic interactions are enhanced. This is similar to the previously reported high pressure effect on EuIn2As2. For x = 0.40, a spin glass state at T
g = 10 K emerges together with the observations of a butter-fly shaped magnetic hysteresis and slow magnetic behavior. Besides, magnetic transition has great influence on the charge carriers in this system and negative colossal magnetoresistance is observed for all P-doped samples. Our findings suggest that EuIn2(As1−x
P
x
)2 is a promising material playground for exploring novel topological states.
Asymmetric Fraunhofer pattern in Josephson junctions from heterodimensional superlattice V5S8
Authors: Fan Juewen , Jiang Bingyan , Zhao Jiaji , Bi Ran , Zhou Jiadong , Liu Zheng , Yang Guang , Shen Jie , Qu Fanming , Lu Li , Kang Ning , Wu Xiaosong
Published: March 2022

Introduction of spin–orbit coupling (SOC) in a Josephson junction (JJ) gives rise to unusual Josephson effects. We investigate JJs based on a newly discovered heterodimensional superlattice V5S8 with a special form of SOC. The unique homointerface of our JJs enables elimination of extrinsic effects due to interfaces and disorder. We observe asymmetric Fraunhofer patterns with respect to both the perpendicular magnetic field and the current. The asymmetry is influenced by an in-plane magnetic field. Analysis of the pattern points to a nontrivial spatial distribution of the Josephson current that is intrinsic to the SOC in V5S8.
Geometric phase under the Unruh effect with intermediate statistics
Authors: Feng Jun , Zhang Jing-Jun , Zhang Qianyi
Published: March 2022

Utilizing the geometric phase (GP) acquired in a quantum evolution, we manifest the thermality and quantum nature of the Unruh effect of an accelerating detector. We consider an UDW detector coupling to a conformal field in Minkowski spacetime, whose response spectrum exhibits an intermediate statistics of (1 + 1) anyon field. We find that comparing to an inertial moving detector, the GP in accelerating frame is modified after the nonunitary evolution of the detector due to the Unruh effect. We show that such modification can distinguish the different thermalizing ways of the detector, which depends on the scaling dimension of the conformal primary field. Finally, we estimate the difference between the GP under the Unruh radiation and that in a thermal bath for a static observer, which reveals the quantum origin of the Unruh effect rather than a conventional thermal noise.
Angular dependence of proton-induced single event transient in silicon-germanium heterojunction bipolar transistors
Authors: Wei Jianan , Li Yang , Liao Wenlong , Liu Fang , Li Yonghong , Liu Jiancheng , He Chaohui , Guo Gang
Published: March 2022

We investigate the angular dependence of proton-induced single event transient (SET) in silicon-germanium heterojunction bipolar transistors. Experimental results show that the overall SET cross section is almost independent of proton incident angle. However, the proportion of SET events with long duration and high integral charge collection grows significantly with the increasing angle. Monte Carlo simulations demonstrate that the integral cross section of proton incident events with high ionizing energy deposition in the sensitive volume tends to be higher at larger incident angles, which is associated with the angular distribution of proton-induced secondary particles and the geometry of sensitive volume.
High-sensitivity methane monitoring based on quasi-fundamental mode matched continuous-wave cavity ring-down spectroscopy
Authors: Li Zhe , Yang Shuang , Zhang Zhirong , Xia Hua , Pang Tao , Wu Bian , Sun Pengshuai , Wang Huadong , Yu Runqing
Published: March 2022

Continuous-wave cavity ring-down spectroscopy (CW-CRDS) is an important technical means to monitor greenhouse gases in atmospheric environment. In this paper, a CW-CRDS system is built to meet the needs of atmospheric methane monitoring. The problem of mode matching is explained from the perspective of transverse mode and longitudinal mode, and the influence of laser injection efficiency on measurement precision is further analyzed. The results of cavity ring-down time measurement show that the measurement precision is higher when the laser is coupled with the fundamental mode. In the experiment, DFB laser is used to calibrate the system with standard methane concentration, and the measurement residual is less than ±4 × 10−4 μs−1. The methane concentration in the air is monitored in real time for two days. The results show the consistency of the concentration changes over the two days, which further demonstrates the reliability of the system for the measurement of trace methane. By analyzing the influence of mode matching, it not only assists the adjustment of the optical path, but also further improves the sensitivity of the system measurement.
Towards traceable dynamic pressure calibration using a shock tube with an optical probe for accurate phase determination
Authors: Amer Eynas , Jönsson Gustav , Arrhén Fredrik
Published: March 2022

In this paper, we introduce a robust method for dynamic characterization of pressure measuring systems used in time-varying pressure applications. The dynamic response of the pressure measuring systems in terms of sensitivity and phase as a function of frequency at various amplitudes of the measurand can be provided. The shock tube which is the candidate primary standard for dynamic pressure calibration at the National Laboratory for pressure, Sweden, was used to realize the dynamic pressure. The shock tube setup used in this study can realize reference pressure with amplitudes up to 1.7 MPa in the frequency range from below a kilohertz up to a megahertz. The amplitude of the realized step pressure was calculated using the Rankine–Hugoniot step relations. In addition, the accurate time of arrival of the generated shock at the device under test (DUT) was measured using an optical probe based on shadowgraphy. The optical detector has a response time in nanosecond time scale which is several orders of magnitude faster than the response time of any pressure measuring system. Hereby, the latency between physical stimuli and response of the DUT can be measured. By the knowledge of the amplitude and the accurate time of arrival of the reference step pressure, the transfer function of the DUT can be calculated and presented in Bode diagrams of sensitivity and phase response versus frequency. The uncertainty in sensitivity and phase measurements was estimated. The information provided by this work is useful for developing reliable models of dynamic pressure measuring system and provide accurate information about their dynamic response. That in turn will contribute to establish a traceability chain for dynamic pressure calibration.
Decoding ECoG signal into 3D hand translation using deep learning
Authors: Śliwowski Maciej , Martin Matthieu , Souloumiac Antoine , Blanchart Pierre , Aksenova Tetiana
Published: March 2022

Objective. Motor brain-computer interfaces (BCIs) are a promising technology that may enable motor-impaired people to interact with their environment. BCIs would potentially compensate for arm and hand function loss, which is the top priority for individuals with tetraplegia. Designing real-time and accurate BCI is crucial to make such devices useful, safe, and easy to use by patients in a real-life environment. Electrocorticography (ECoG)-based BCIs emerge as a good compromise between invasiveness of the recording device and good spatial and temporal resolution of the recorded signal. However, most ECoG signal decoders used to predict continuous hand movements are linear models. These models have a limited representational capacity and may fail to capture the relationship between ECoG signal features and continuous hand movements. Deep learning (DL) models, which are state-of-the-art in many problems, could be a solution to better capture this relationship. Approach. In this study, we tested several DL-based architectures to predict imagined 3D continuous hand translation using time-frequency features extracted from ECoG signals. The dataset used in the analysis is a part of a long-term clinical trial (ClinicalTrials.gov identifier: NCT02550522) and was acquired during a closed-loop experiment with a tetraplegic subject. The proposed architectures include multilayer perceptron, convolutional neural networks (CNNs), and long short-term memory networks (LSTM). The accuracy of the DL-based and multilinear models was compared offline using cosine similarity. Main results. Our results show that CNN-based architectures outperform the current state-of-the-art multilinear model. The best architecture exploited the spatial correlation between neighboring electrodes with CNN and benefited from the sequential character of the desired hand trajectory by using LSTMs. Overall, DL increased the average cosine similarity, compared to the multilinear model, by up to 60%, from 0.189 to 0.302 and from 0.157 to 0.249 for the left and right hand, respectively. Significance. This study shows that DL-based models could increase the accuracy of BCI systems in the case of 3D hand translation prediction in a tetraplegic subject.
Nonlinear decay of high-power microwaves into trapped modes in inhomogeneous plasma
Authors: Tancetti A. , Nielsen S.K. , Rasmussen J. , Gusakov E.Z. , Popov A.Yu. , Moseev D. , Stange T. , Senstius M.G. , Killer C. , Vecséi M. , Jensen T. , Zanini M. , Abramovic I. , Stejner M. , Anda G. , Dunai D. , Zoletnik S. , Laqua H.P. , the W7-X Team
Published: March 2022

We present novel experimental evidence of parametric decay instability of microwave beams in the plasma edge of the Wendelstein 7-X stellarator. We propose that the instability is sustained by trapping of only one daughter wave in the non-monotonic density profile measured with high spatial resolution within a stationary magnetic island. The power levels and spectral shapes of the detected microwave signal are reproduced by numerical modelling and a theoretical power threshold is predicted around 300 kW, comparable with observations. We predict a fraction of power drained by daughter waves around 4% in the experiments, potentially increasing above 50% for more hollow edge density profiles. Such absorption levels could significantly reduce the efficiency of the microwave heating and current-drive system in tokamaks and stellarators.
Overwintering fires rising in eastern Siberia
Authors: Xu Wenxuan , Scholten Rebecca C , Hessilt Thomas D , Liu Yongxue , Veraverbeke Sander
Published: March 2022

Overwintering fires are a historically rare phenomenon but may become more prevalent in the warming boreal region. Overwintering fires have been studied to a limited extent in boreal North America; however, their role and contribution to fire regimes in Siberia are still largely unknown. Here, for the first time, we quantified the proportion of overwintering fires and their burned areas in Yakutia, eastern Siberia, using fire, lightning, and infrastructure data. Our results demonstrate that overwintering fires contributed to 3.2 ± 0.6% of the total burned area during 2012–2020 over Yakutia, compared to 31.4 ± 6.8% from lightning ignitions and 51.0 ± 6.9% from anthropogenic ignitions (14.4% of the burned area had unknown cause), but they accounted for 7.5 ± 0.7% of the burned area in the extreme fire season of 2020. In addition, overwintering fires have different spatiotemporal characteristics than lightning and anthropogenic fires, suggesting that overwintering fires need to be incorporated into fire models as a separate fire category when modelling future boreal fire regimes.
Subnational assessment of threats to Indian biodiversity and habitat restoration opportunities
Authors: Chaudhary Abhishek , Mair Louise , Strassburg Bernardo B N , Brooks Thomas M , Menon Vivek , McGowan Philip J K
Published: March 2022

The active involvement of subnational authorities, cities and local governments has been identified as one of the enabling conditions to implement the Convention on Biological Diversity’s Post-2020 Global Biodiversity Framework and progress towards the United Nations’ Sustainable Development Goal 15 (Life on Land). However, there has not been any systematic application of any biodiversity metric at the subnational level to identify where the main responsibilities and opportunities lie within a country. Here, we therefore apply the recently proposed species threat abatement and restoration (STAR) metric for amphibians, birds and terrestrial mammals in 36 states and 666 districts of India, one of 17 megadiverse countries. The STAR metric takes into account the endemicity and the scope and severity of all threats affecting each species’ population hosted by the region and can quantify the potential contribution of threat mitigation and habitat restoration in a particular region towards global biodiversity goals. The larger the STAR metric score, the larger the contribution of a specified area for global species conservation. Out of 97 individual threats affecting species in India, we found that crop production is the major threat, contributing 44% of the total national STAR score followed by biological resource use such as hunting and logging (23%), and residential and commercial development (11%). Just seven out of 36 states and 66 out of 666 districts hosting high numbers of threatened and endemic species contribute 80% to the national STAR score. Importantly, the states and districts with most potential to contribute to threat abatement do not always overlap with those where habitat restoration will yield high benefits. Our analysis demonstrates the applicability and value of the STAR metric to subnational governments for biodiversity conservation elsewhere in the world.
Future PM2.5 emissions from metal production to meet renewable energy demand
Authors: Rathod Sagar D , Bond Tami C , Klimont Zbigniew , Pierce Jeffrey R , Mahowald Natalie , Roy Chaitri , Thompson John , Scott Ryan P , Hoal Karin Olson , Rafaj Peter
Published: March 2022

A shift from fossil fuel to renewable energy is crucial in limiting global temperature increase to 2 °C above preindustrial levels. However, renewable energy technologies, solar photovoltaics, wind turbines, and electric vehicles are metal-intensive, and the mining and smelting processes to obtain the needed metals are emission-intensive. We estimate the future PM2.5 emissions from mining and smelting to meet the metal demand of renewable energy technologies in two climate pathways to be 0.3–0.6 Tg yr−1 in the 2020–2050 period, which are projected to contribute 10%–30% of total anthropogenic primary PM2.5 combustion emissions in many countries. The concentration of mineral reserves in a few regions means the impacts are also regionally concentrated. Rapid decarbonization could lead to a faster reduction of overall anthropogenic PM2.5 emissions but also could create more unevenness in the distributions of emissions relative to where demand occurs. Options to reduce metal-related PM2.5 emissions by over 90% exist and are well understood; introducing policy requiring their installation could avoid emission hotspots.
East African population exposure to precipitation extremes under 1.5 °C and 2.0 °C warming levels based on CMIP6 models
Authors: Ayugi Brian , Jiang Zhihong , Iyakaremye Vedaste , Ngoma Hamida , Babaousmail Hassen , Onyutha Charles , Dike Victor Nnamdi , Mumo Richard , Ongoma Victor
Published: March 2022

Understanding population exposure to precipitation-related extreme events is important for effective climate change adaptation and mitigation measures. We analyze extreme precipitation using indices (EPIs), including consecutive dry days (CDD), annual total precipitation, simple daily intensity, and the number of extremely wet days, under the past and future climatic conditions over East Africa. The exposure of the East African population to these extreme events at 1.5 °C and 2.0 °C global warming levels (GWLs) is analyzed based on Climate Model Intercomparison Project phase 6 models. Exposure is computed from extremely wet and dry days (R95p and CDD, respectively). Under both GWLs, EPIs (except CDD) averaged over East Africa are projected to increase under the Shared Socio-economic Pathways (SSP)2-4.5 and SSP5-8.5 scenarios. The largest increase in wet events will likely occur in eastern and northern Kenya. The results also reveal an intensification of precipitation extremes over Burundi, Rwanda, and some parts of Uganda. However, small changes are expected over most parts of Kenya and Tanzania. Examination of population exposure to EPIs shows that the most prominent and net intense occurrence is over Burundi, Rwanda, and some parts of Uganda. In contrast, less change is noted to occur over vast parts of Kenya and Tanzania. Meanwhile, limiting the warming target to less than 1.5 °C but not more than 2.0 °C has 37% (44.2%) and 92% (4%) less impact on the occurrence of EPIs for R95p (CDD) under SSP2-4.5 (SSP5-8.5) scenarios, respectively. The study establishes that future exposure is predominantly driven by changes in population compared to other factors such as climate or concurrent changes in climate and population (the nonlinear interaction effect). For instance, climate effects are anticipated to contribute ∼10.6% (12.6%) of the total change in population exposure under 1.5 °C (2.0 °C) warming levels, while population and interaction effects are expected to contribute ∼77.4% (71.9%) and 12% (15.5%), respectively, under 1.5 °C (2.0 °C) scenarios. Interestingly, the projected changes in regional exposure due to the interaction effects under SSP2-4.5 are greater than the climate effect, while the reverse pattern is observed under SSP5-8.5. For example, under SSP5-8.5, climate effects for 1.5 °C and 2.0 °C are larger (after population effect) with ∼3.8 × 105 (15.7%) and ∼6.1 × 105 (17.5%) billion person-mm, respectively. The high exposure noted over East Africa calls for a shift in policies to instate suitable adaptation measures to cushion the already vulnerable population.
Local preservation of no-signaling in multiparty PT-symmetric evolutions
Authors: Kumari Asmita , Sen Ujjwal
Published: March 2022

Violation of the no-signaling principle may occur in PT-symmetric evolutions, that is, evolutions that stem from Hamiltonians that are symmetric with respect to parity and time-reversal, of bipartite entangled states. The violation can be avoided by using a non-conventional inner product. We show that even within the formalism that utilizes the conventional inner product between physical state vectors in a separable Hilbert space, it is possible to obtain instances of local preservation of the no-signaling principle for evolutions corresponding to PT-symmetric non-Hermitian Hamiltonians with real eigenvalues, of multiparty entangled states, whose bipartite versions still violate the principle. The phenomenon can be witnessed already by using the Greenberger–Horne–Zeilinger state. Interestingly, the generalized W states do not support such a local preservation of no-signaling.
Studying the influence of shading devices on indoor thermal comfort in desert and Mediterranean climates
Authors: Berkouk D , Bouzir TAK , Mazouz S , Boucherit S , Mokhtari N
Published: March 2022

Thermal comfort is regarded as the most important issue in residential buildings. To verify the thermal performance of the envelope components used for the promotional apartments in Algeria, whether they are adapted to the hot and dry southern climate, or the Mediterranean climate, and to understand the effect of fixed and combined horizontal and vertical shading devices of different dimensions (12 cm, 25 cm, and 50 cm) on the indoor thermal comfort of these apartments, two main climatic zones have been considered in this study, the first is a desert climate of (Biskra, Ghardaïa, and Ouargla), while the second is a Mediterranean climate of (Algiers, Oran, Bari, and Naples). The methodology of this research was based on a comparative approach to the outcomes of a stay in an apartment in Biskra, which was looked at as a model for other desert and Mediterranean cities, based on the operative temperature data of different scenarios obtained through several simulations, which conducted by the use TrnSys software. The findings suggest that the double-walled hollow brick envelope causes a very severe indoor thermal environment (To<29) in dwellings located in desert regions such as Biskra, Ghardaïa, and Ouargla. In addition, the findings also suggest that shading devices are more effective for apartments located in the Mediterranean region (Algiers, Oran, Bari, Naples) than those located in the desert region. In the desert region, the use of mechanical cooling devices in the summer period is considered the most adequate solution to ensure the occupants’ thermal comfort. To identify the most optimal shading device models, future research based on the parametric simulation of kinetic shading devices is needed.
A Proposed Methodology for Detecting the Urban Footprint in Egypt
Authors: Mahmoud N. , Samir N. , Fathi A. , Mohamed W.
Published: March 2022

The detection of informal built-up environments that sprawl on agricultural land is difficult to codify specially in particular with the increase in the population in the Arab Republic of Egypt. In 2017, a law was passed to remove building infractions in rural areas according to aerial photographs taken by the military and the building codes built after the 2019 Construction Violations Reconciliation Law (CVRL) were regulated, which mandates the demolition of any buildings built without a permit that are capped at 8.2 million units Since 2007. The use of remote sensing, which is a powerful technology that relies specifically on updated satellite images, is a key tool for detecting infringements built-up regions. The European Space Agency’s Sentinel Synthetic Aperture Radar (SAR) constellation is a key component of this research because of its advantages that allow for improved spatial resolution and atmospheric independence, and it takes day and night images, making it useful for a wide range of ground cover detection applications., a technological advantage that surpasses Optical sensors for the Sentinel 2 and Landsat missions that rely on clear weather conditions. The study aims to evaluate the use of radar satellites compared to optical satellites to detect urban built-up areas and encroachments on agricultural areas. The study was conducted on an area of 64 square kilometres, in Damietta City, East Delta, Egypt. Supervised classification was also used to derive the overall accuracy of radar satellite images and compare them with optical satellite images, using Error Matrix tables on Scup + QGIS programs. The results of the study resulted in reaching a high accuracy of land cover classification from the process of combining the Sentinel-1A,1B images in Maximum likelihood (ML) algorithms compared to Sentinel-2 images, reaching up to an overall accuracy (OA) of 80%, while the classification in Random Forest (RF) algorithms reached an overall accuracy (OA) of 87%. This paper recommends using the method of merging (SAR) Sentinel 1A,1B images and applying it, as well as conducting periodic monitoring of urban expansions using remote sensing techniques, to make sustainable decisions for the future of urban expansion master plans in the region and to quickly explore informal built-up encroachments.
Study on the influence of auxiliary electrode and magnet on electrochemical machining of SS304 using NaCl and NaNO3
Authors: J Deepak , P Hariharan
Published: March 2022

SS304 is a potential material for the use in defense, medical, aerospace, and automotive industries owing to its excellent mechanical and chemical properties. Machining of SS304 is a topic of great research interest and complex shapes can be produced effectively using Electrochemical machining (ECM). However stray corrosion is a problem in ECM that has a negative impact on the process. Moreover, acids are widely used as electrolytes in ECM. The use of eco-friendly electrolytes saves the operator and the environment from the threats associated with the use of acids as electrolytes. Hence in this study, eco-friendly electrolytes (NaCl and NaNO3) are used. This paper presents a study to reduce the adverse effect of stray corrosion using a magnet, an auxiliary electrode, and a combination of both on two eco-friendly electrolytes using SS304 as workpiece. The evaluation was done based on Taper angle, Radial overcut, MRR, Surface roughness, and Radial-Stray current affected zone. The magnet was placed below the workpiece using a 3D-printed fixture. From the experiments conducted it has been found that the use of Aluminum as an auxiliary electrode is effective when using NaCl as an electrolyte. Up to 37% decrease in taper angle and a 63% reduction in surface roughness was observed when machining was done under the influence of a magnet using NaCl, due to the formation of vortex flow in the machining zone.