bluuebunny/crossref_metadata_2025 huggingface dataset:
Intelligibility, Speech Rate, and Communication Efficiency in Children With Neurological Conditions: A Longitudinal Study of Childhood Dysarthria
Authors: Haas Elisabet , Ziegler Wolfram , Schölderle Theresa
Published: June 2022

Purpose:

This study aimed to describe communication-related parameters (i.e., intelligibility, speech rate, and communication efficiency) and their developmental courses in children with neurological conditions against the background of typical development. In addition, interrelations between the developmental courses of communication-related parameters and auditory-perceptual ratings related to speech subsystems were investigated.

Method:

Fourteen children with neurological conditions (CNC) and 14 typically developing children (CTD), matched for age and gender (four girls; 5;1–8;4 [years;months] at first examination), were assessed at three points in time over an 18-month period. Speech samples were collected using the Bogenhausener Dysarthrie Skalen–Kindliche Dysarthrien (English: Bogenhausen Dysarthria Scales–Childhood Dysarthria), a German tool for the assessment of childhood dysarthria. To assess intelligibility, naïve listeners transcribed audio samples of sentence repetitions of the children. Speech rate was measured by acoustic analyses, and communication efficiency was determined by multiplying the proportion of correctly transcribed syllables with speech rate. Age normalization was performed following a recently published approach.

Results:

On the group level, CNC had conspicuous raw and normalized scores for the three communication-related parameters and were more variable than the CTD group regarding their developmental courses. These differences were more pronounced for intelligibility than for speech rate. A strong relationship between communication-related and speech subsystems–related auditory-perceptual characteristics was apparent only between intelligibility and articulation/resonance.

Conclusions:

For the first time, age-normalized scores for communication-related parameters were reported in children with neurological disorders and put into a developmental context within the framework of a longitudinal study. Age-normalized intelligibility was more vulnerable to large developmental changes than speech rate and was best predicted by changes in articulation and resonance. Overall, this study may contribute to a more comprehensive and valid clinical assessment of childhood dysarthria and to a better understanding of its developmental dynamics.
A reinforcement learning backstepping‐based control design for a full vehicle active Macpherson suspension system
Authors: Lin Yu‐Chen , Nguyen Ha Ly Thi , Yang Ji‐Fan , Chiou Hung‐Jui
Published: June 2022

This paper presents a reinforcement learning backstepping‐based control scheme for the design of a full vehicle active suspension system such that both the superior ride comfort and stabilization are achieved. It is well known that the traditional backstepping control scheme is suitable to solve higher order nonlinear system based on the strict‐feedback form; however, the disadvantage of the procedure requires computing the derivatives of virtual control signals, which is a very complex task. Therefore, a reinforcement learning scheme using the deep deterministic policy gradient (DDPG) control strategy is developed to replace the process of finding virtual control force in backstepping method. It not only avoids the complexity of analytically calculating the derivatives of the virtual control signals, but also retains the systems robustness when there exist random disturbances from road irregularities. To verify the performance of the proposed active suspension control scheme, the random road unevenness profiles according to ISO 8608 is considered as vertical and lateral disturbance input excitation of a full‐vehicle suspension system. Compared with conventional passive suspension system and backstepping control scheme, the proposed approach can be demonstrated to not only effectively improve ride comfort under random road excitation, but also improve the transient response and robustness.
A tooth surface design method combining semantic guidance, confidence, and structural coherence
Authors: Wang Peng , Tian Yan , Liu Nali , Wang Jialei , Chai Shuangming , Wang Xun , Wang Ruili
Published: June 2022

Research on tooth surface design based on deep neural networks has recently achieved progress in terms of both accuracy and execution efficiency. However, unrealistic outputs are still a challenging issue, partially because of (1) the lack of semantic guidance, (2) the inability to discover and rectify false results, and (3) the lack of exploration of structural coherence in intermediate layers. In this paper, we present an approach to predict depth images for designed teeth based on a conditional generative adversarial network (CGAN) by incorporating semantic guidance. Moreover, the uncertainty of semantic inference is employed to improve the model outputs, and a structural coherence loss is proposed for adversarial learning to enhance the discrimination capability of the network in intermediate layers. We evaluate the performance of our approach with the Shining3D tooth dataset. The experimental results show that our method produces better results than the other available approaches in terms of accuracy.
Simple PDF of the sum and maximum of non‐identical fluctuating two‐ray variates
Authors: Al‐Hmood Hussien , Abbas Rafed S. , Al‐Raweshidy Hamed
Published: June 2022

In this letter, probability density function (PDF) of the sum and maximum of non‐identical fluctuating two‐ray (FTR) variates are derived in terms of the power and exponential functions. To this effect, novel mathematically tractable expressions of the outage probability (OP) and average bit error probability (ABEP) for both the maximal ratio combining (MRC) and selection combining (SC) diversity receptions are provided. The numerical results are affirmed by the Monte‐Carlo simulations for different scenarios.
Design and implementation of a fault detection method for a PV‐fed DC‐microgrid with power control mechanism
Authors: Zakir Muhammad , Arshad Ammar , Sher Hadeed Ahmed , Al‐Durra Ahmed
Published: June 2022

This paper presents practical implementation of a fault detection, localisation, and categorisation (FDLC) method in PV‐fed DC‐microgrid (DCMG). The DCMG is implemented by utilising a group of two DC nanogrids (DCNG) that have power control mechanism (PCM). The FDLC uses a voltage calculating circuit comprising a single voltage sensor and diode network. Moreover, the architecture is based on six statements extracted from the investigation of line to line (L–L) and line to ground (L–G) faults at a DCNG of the cluster. The PCM in the proposed system utilises a power triggering circuit for effective power flow among the different units of the DCNG considering the load demands and the resource availability. Experimentation is carried out by creating L–L/L–G faults at different points in the DCMG. Detection, localisation, and classification of faults is performed by utilising the sensor's voltage and power of the individual DCNG. FDLC offers less computational burden, perform fast detection of fault, and is capable of distinguishing between the L–L/L–G faults and uniform irradiance and partial shading conditions in the PV‐array. The proposed FDLC technique and its six statements are verified through experimental results.
Fast algorithm for box‐constrained fractional‐order total variation image restoration with impulse noise
Authors: Zhu Jianguang , Wei Juan , Hao Binbin
Published: June 2022

In this paper, a novel variational model with box constraints is proposed to restore images corrupted by impulse noise. The proposed model is composed of fractional‐order total variation regularization and Lp‐fidelity term . Moreover, the new model possesses the advantages of preserving sharp edges and removing blocking effect. To solve the proposed model, some auxiliary variables are first introduced to transform it into some easy‐to‐solve subproblems. Further, the alternating direction method of multipliers, iteratively re‐weighted ℓ1 algorithm and fast iteration technique are adopted to solve the related subproblems. Numerical results show that the proposed model performs better in comparison with the several existing methods, in terms of both quantitative evaluation and visual quality.
Design and optimization of yokeless magnetic gear with asymmetric Halbach permanent magnet array for electric vehicle powertrain
Authors: Chen Yuanxi , Zhao Xing , Ho Siulau , Niu Shuangxia , Fu Weinong
Published: June 2022

In this paper, a novel 3/27/24 (pole pairs of inner rotor permanent magnet [PM]s/modulator/outer rotor PMs) high torque density yokeless magnetic gear with asymmetric Halbach PM array is presented and optimized for electric vehicle powertrain. The key is to improve the torque performance by replacing the magnetic steel with the light nonmagnetic material as the rotor core and employing the embedded magnetic steel bar as well as trapezoidal PM structure to form a low magnetic resistance in the magnetic circuit. The proposed machine has significant performance improvements in two aspects. Firstly, it has high torque density and low iron loss with the yokeless structure. Secondly, it has a high anti‐saturation capability and low torque ripple with the asymmetric Halbach PM array and the embedded magnetic steel bar. The proposed structure is optimized by the co‐simulation of the finite‐element method and C++ optimization software. For a clear evaluation, the proposed structure is compared with generalized solutions in terms of performance and cost. Comparison results indicate that the proposed solution has the highest output torque, torque density, and torque per PM weight among solutions, reaching 214.1 N·m, 58.2 N·m/kg, and 95.6 N·m/kg, which greatly enhances the performance of the magnetic gear.
Transit least-squares survey
Authors: Heller René , Harre Jan-Vincent , Samadi Réza
Published: June 2022

In its long-duration observation phase, the PLATO satellite (scheduled for launch in 2026) will observe two independent, non-overlapping fields, nominally one in the northern hemisphere and one in the southern hemisphere, for a total of four years. The exact duration of each pointing will be determined two years before launch. Previous estimates of PLATO’s yield of Earth-sized planets in the habitable zones (HZs) around solar-type stars ranged between 6 and 280. We use the PLATO Solar-like Light curve Simulator (PSLS) to simulate light curves with transiting planets around bright (mV ≤ 11) Sun-like stars at a cadence of 25 s, roughly representative of the >15 000 targets in PLATO’s high-priority P1 sample (mostly F5-K7 dwarfs and subdwarfs). Our study includes light curves generated from synchronous observations of 6, 12, 18, and 24 of PLATO’s 12 cm aperture cameras over both 2 and 3yr of continuous observations. Automated detrending is done with the Wotan software, and post-detrending transit detection is performed with the transit least-squares (TLS) algorithm. Light curves combined from 24 cameras yield true positive rates (TPRs) near unity for planets ≥1.2 R⊕ with two transits. If a third transit is in the light curve, planets as small as 1 R⊕ are recovered with TPR ~ 100%. We scale the TPRs with the expected number of stars in the P1 sample and with modern estimates of the exoplanet occurrence rates and predict the detection of planets with 0.5 R⊕ ≤ Rp ≤ 1.5 R⊕ in the HZs around F5-K7 dwarf stars. For the long-duration observation phase (2yr + 2yr) strategy we predict 11–34 detections, and for the (3 yr + 1 yr) strategy we predict 8–25 discoveries. These estimates neglect exoplanets with monotransits, serendipitous detections in stellar samples P2–P5, a dedicated removal of systematic effects, and a possible bias of the P1 sample toward brighter stars and high camera coverage due to noise requirements. As an opposite effect, Earth-sized planets might typically exhibit transits around P1 sample stars shallower than we have assumed since the P1 sample will be skewed toward spectral types earlier than the Sun-like stars assumed in our simulations. Moreover, our study of the effects of stellar variability on shallow transits of Earth-like planets illustrates that our estimates of PLATO’s planet yield, which we derive using a photometrically quiet star similar to the Sun, must be seen as upper limits. In conclusion, PLATO’s detection of about a dozen Earth-sized planets in the HZs around solar-type stars will mean a major contribution to this as yet poorly sampled part of the exoplanet parameter space with Earth-like planets.
The rotational kinetic Sunyaev–Zeldovich contribution to the temperature asymmetry toward the M 31 halo
Authors: Tahir Noraiz , De Paolis Francesco , Qadir Asghar , Nucita Achille A.
Published: June 2022

Temperature asymmetry in the cosmic microwave background (CMB) data by the Planck satellite has been discovered and analyzed toward several nearby edge-on spiral galaxies. It provides a way to probe galactic halo rotation, and to constrain the baryon fraction in the galactic halos. The frequency independence of the observed data provides a strong indication of the Doppler shift nature of the effect, due to the galactic halo rotation. It was proposed that this effect may arise from the emission of cold gas clouds populating the galactic halos. However, in order to confirm this view, other effects that might give rise to a temperature asymmetry in the CMB data, have to be considered and studied in detail. The main aim of the present paper is to estimate the contribution in the CMB temperature asymmetry data due to the free-free emission by hot gas (particularly electrons) through the rotational kinetic Sunyaev–Zeldovich (rkSZ) effect. We concentrate, in particular, on the M 31 galactic halo and compare the estimated values of the rkSZ induced temperature asymmetry with those obtained by using the SMICA pipeline of the Planck data release, already employed to project out the SZ sources and for lensing studies. As an additional consistency check, we also verified that the hot gas diffuse emission in the X-ray band does not exceed that detected in the soft X-ray band by ROSAT observations. We note that our results clearly show that the rkSZ effect gives only a minor contribution to the observed M 31 halo temperature asymmetry by Planck data.
Coronal mass ejection followed by a prominence eruption and a plasma blob as observed by Solar Orbiter
Authors: Bemporad A. , Andretta V. , Susino R. , Mancuso S. , Spadaro D. , Mierla M. , Berghmans D. , D’Huys E. , Zhukov A. N. , Talpeanu D.-C. , Colaninno R. , Hess P. , Koza J. , Jejčič S. , Heinzel P. , Antonucci E. , Da Deppo V. , Fineschi S. , Frassati F. , Jerse G. , Landini F. , Naletto G. , Nicolini G. , Pancrazzi M. , Romoli M. , Sasso C. , Slemer A. , Stangalini M. , Teriaca L.
Published: June 2022

Context. On 2021 February 12, two subsequent eruptions occurred above the western limb of the Sun, as seen along the Sun-Earth line. The first event was a typical slow coronal mass ejection (CME), followed ∼7 h later by a smaller and collimated prominence eruption, originating south of the CME, followed by a plasma blob. These events were observed not only by the SOHO and STEREO-A missions, but also by the suite of remote-sensing instruments on board Solar Orbiter.

Aims. We show how data acquired by the Full Sun Imager (FSI), the Metis coronagraph, and the Heliospheric Imager (HI) from the Solar Orbiter perspective can be combined to study the eruptions and different source regions. Moreover, we show how Metis data can be analyzed to provide new information about solar eruptions.

Methods. Different 3D reconstruction methods were applied to the data acquired by different spacecraft, including remote-sensing instruments on board Solar Orbiter. Images acquired by the two Metis channels in the visible light (VL) and H I Ly-α line (UV) were combined to derive physical information about the expanding plasma. The polarization ratio technique was also applied for the first time to Metis images acquired in the VL channel.

Results. The two eruptions were followed in 3D from their source region to their expansion in the intermediate corona. By combining VL and UV Metis data, the formation of a post-CME current sheet (CS) was followed for the first time in the intermediate corona. The plasma temperature gradient across a post-CME blob propagating along the CS was also measured for the first time. Application of the polarization ratio technique to Metis data shows that by combining four different polarization measurements, the errors are reduced by ∼5 − 7%. This constrains the 3D plasma distribution better.
Contribution of flows around active regions to the north-south helioseismic travel-time measurements
Authors: Poulier P.-L. , Liang Z.-C. , Fournier D. , Gizon L.
Published: June 2022

Context. In local helioseismology, the travel times of acoustic waves propagating in opposite directions along the same meridian inform us about horizontal flows in the north-south direction. The longitudinal averages of the north-south helioseismic travel-time shifts vary with the sunspot cycle.

Aims. We aim to study the contribution of inflows into solar active regions to this solar-cycle variation.

Methods. To do so, we identified the local flows around active regions in the horizontal flow maps obtained from correlation tracking of granulation in continuum images of the Helioseismic and Magnetic Imager onboard the Solar Dynamics Observatory. We computed the forward-modeled travel-time perturbations caused by these inflows using 3D sensitivity kernels. In order to compare with the observations, we averaged these forward-modeled travel-time perturbations over longitude and time in the same way as the measured travel times.

Results. The forward-modeling approach shows that the inflows associated with active regions may account for only a fraction of the solar-cycle variations in the north-south travel-time measurements.

Conclusions. The travel-time perturbations caused by the large-scale inflows surrounding the active regions do not explain in full the solar-cycle variations seen in the helioseismic measurements of the meridional circulation.
The role of highly vibrationally excited H2 initiating the nitrogen chemistry
Authors: Goicoechea Javier R. , Roncero Octavio
Published: June 2022

The formation of hydrides by gas-phase reactions between H2 and a heavy element atom is a very selective process. Reactions with ground-state neutral carbon, oxygen, nitrogen, and sulfur atoms are very endoergic and have high energy barriers because the H2 molecule has to be fragmented before a hydride bond is formed. In cold interstellar clouds, these barriers exclude the formation of CH, OH, NH, and SH radicals through hydrogen abstraction reactions. Here we study a very energetically unfavorable process, the reaction of N(4S) atoms with H2 molecules. We calculated the reaction rate coefficient for H2 in different vibrational levels, using quantum methods for v = 0−7 and quasi-classical methods up to v =12; for comparison purposes, we also calculated the rate coefficients of the analogous reaction S (3P)+ H2(v) → SH + H. Owing to the high energy barrier, these rate coefficients increase with v and also with the gas temperature. We implemented the new rates in the Meudon photodissociation region (PDR) code and studied their effect on models with different ultraviolet (UV) illumination conditions. In strongly UV-irradiated dense gas (Orion Bar conditions), the presence of H2 in highly vibrationally excited levels (v ≥ 7) enhances the NH abundance by two orders of magnitude (at the PDR surface) compared to models that use the thermal rate coefficient for reaction N(4S) + H2 → NH + H. The increase in NH column density, N(NH), across the PDR is a factor of ~25. We investigate the excitation and detectability of submillimeter NH rotational emission lines. Being a hydride, NH excitation is very subthermal (Trot ≪ Tk) even in warm and dense gas. We explore existing Herschel/HIFI observations of the Orion Bar and Horsehead PDRs. We report a 3σ emission feature at the ~974 GHz frequency of the NH NJ = 12 − 01 line toward the Bar. The emission level implies N(NH) ≃ 1013 cm−2, which is consistent with PDR models using the new rate coefficients for reactions between N and UV-pumped H2. This formation route dominates over hydrogenation reactions involving the less abundant N+ ion. JWST observations will quantify the amount and reactivity of UV-pumped H2 in many interstellar and circumstellar environments.
Plant system study of France–Japan common concept on Sodium-cooled Fast Reactor
Authors: Kato Atsushi , Yamamoto Tomohiko , Ando Masato , Chikazawa Yoshitaka , Murakami Hisatomo , Oyama Kazuhiro , Kaneko Fumiaki , Higurashi Koichi , Chanteclair Frédéric , Chenaud Marie-Sophie , Dechelette Franck , Hourcade Edouard , Plancq David , Rodriguez Gilles , Carluec Bernard , Dauphin Alexandre , Dirat Jean-François , Hirn Julien
Published: June 2022

This paper provides an overview of plant system studies to establish a common technical view for Sodium-cooled Fast Reactor (SFR) concept (the common SFR concept) between France and Japan based on ASTRID 600 and the new concept with downsized output (ASTRID150). One of important issues on a reactor structure design is to enhance seismic resistance to be tolerable against strong earthquake such that postulated in Japan. A concept of High Frequency Design (HFD) is shared, in which the natural frequency of the reactor structure should be higher than that of peak acceleration of vertical floor seismic response with a horizontal seismic isolation system. The design options related to HFD have been examined and design recommendations are established. ASTRID 600 adopted a gas power conversion system to strictly eliminate the chemical reaction risks due to the proximity of sodium and water in the steam generator units. On the other hand, a steam generator (SG) is thought to be a concept with high technical readiness level and is a reference option in Japan and a backup option in France. Then, design comparison of the SG with single-walled helical coil tubes was mainly conducted in this study from the viewpoint of safety and so on. A common concept of a decay heat removal system is discussed to achieve practical elimination of loss of decay heat removal function. A fuel handling system studies are performed to eliminate and ex-vessel storage of spent fuels in sodium to reduce a construction cost. An adequate confinement system is investigated to achieve practical mitigation of large radiological release to the environment even under the condition of core destructive accident.
Ion beam figuring with focused anode layer thruster
Authors: Girka O. I. , Lee K. I. , Choi Y. S. , Jang S. O.
Published: June 2022

This work presents the peculiarities of cone ion beam formation with a focused thruster with anode layer (TAL) and its application to silicon carbide (SiC) ion beam figuring. Modeling results of Lorentz E × B force distribution in the discharge gap are presented. 3D particle tracing for keV Ar ions is carried out for the first time in the beam drift region of TAL with magnetic lens. Extracted ion beam full width at half maxima is about 2 mm in the focal plane, where the SiC etching rate reaches 0.5 µm/min. The SiC sputter yields are measured as a function of the Ar ion impact energy and beam incidence angle. The maximum sputter yield of 2.8 atom/ion is observed at 45° of the beam-sample angle for the Si targets. Furthermore, the maximum sputter yield value of 1.7 atom/ion is measured at 30° of the beam-sample angle for the SiC targets. The novelty of present research is in the application of focused TAL keV Ar ion beam to the SiC ion beam figuring.
High-performance dual-gate graphene pH sensors
Authors: Le Son T. , Cho Seulki , Zaslavsky Alexander , Richter Curt A. , Balijepalli Arvind K.
Published: June 2022

Field-effect transistors (FETs) are versatile tools for high-precision biophysical measurements, and their measurement sensitivity and resolution can be improved by using innovative materials and device designs. Here, we report on the sensitivity and noise performance of dual-gated graphene FETs. When measuring pH, our devices exhibit a sensitivity of up to 30 V per unit change in pH, ≈500-fold greater than the Nernst value at room temperature, and noise-limited resolution of 2 × 10−4 in the biomedically relevant 0.1–10 Hz bandwidth. This level of performance is obtained due to a highly asymmetric dual-gate design utilizing an ionic liquid top-gate dielectric coupled with graphene's large intrinsic quantum capacitance (≈15 μC/cm2). Our results improve upon the sensitivity and resolution of previously demonstrated Si- and MoS2-channel FET biosensors.
SnO2 modified mesoporous ZrO2 as efficient electron-transport layer for carbon-electrode based, low-temperature mesoscopic perovskite solar cells
Authors: Guo De'en , Ma Jiao , Lin Siyuan , Guo Xiao , Huang Han , Kong Deming , Xu Fuxin , Gao Yongli , Zhang Wenhao , Hu Yue , Zhou Conghua
Published: June 2022

SnO2 modified mesoporous ZrO2 is used to replace the mesoporous TiO2 layer and serves as a kind of mesoporous electron-transport layer during the low-temperature fabrication of mesoscopic perovskite solar cells that are based on carbon electrode. X-ray/ultraviolet photoelectron spectroscopy studies and electrical test observe that SnO2 modification brought down the work function while increasing the conductivity of the mesoporous ZrO2. Transient photovoltage/photocurrent decay curves, impedance spectroscopy, and photoluminescence mapping show that after the bottom layer of ZrO2 is modified by SnO2, the charge extraction process is accelerated while recombination is retarded. This modification helps to increase the power conversion efficiency from 4.70 (±0.85)% to 10.15 (±0.35)%, along with the optimized efficiency at 13.37% (AM1.5G, 100 mW/cm2) for the low-temperature devices. In addition, the effects of modification layers of SnO2 on the power conversion properties are carefully studied. This study shows that SnO2 modified mesoporous ZrO2 could serve as an efficient electron-transport layer for the low-temperature mesoscopic devices.
Role of long-range interaction on the electrical transport and electron–phonon scattering in thermoelectric Mg2Si
Authors: Xia Chengliang , Chen Yue
Published: June 2022

Many thermoelectrics are polar materials, where the long-range interaction plays a non-negligible role; however, its effect on the electrical transport property of thermoelectric materials is yet to be fully investigated. In this work, we demonstrate the importance of long-range interaction on the electrical transport property and the electron–phonon scattering mechanism in thermoelectric Mg2Si. We find that agreement between experimental and theoretical electrical conductivities can be significantly improved after considering the long-range interaction. In addition, we also demonstrate the importance of long-range interaction for studying the effect of band convergence on thermoelectric properties.
Thermal boundary conductance of CVD-grown MoS2 monolayer-on-silica substrate determined by scanning thermal microscopy
Authors: Frausto-Avila Christian Mateo , Arellano-Arreola Victor M. , Yañez Limon Jose Martin , De Luna-Bugallo Andres , Gomès Séverine , Chapuis Pierre-Olivier
Published: June 2022

We characterize heat dissipation of supported molybdenum disulfide (MoS2) monolayers grown by chemical vapor deposition by means of ambient-condition scanning thermal microscopy (SThM). We find that the thermal boundary conductance of the MoS2 monolayers in contact with 300 nm of SiO2 is around 4.6 ± 2 MW m−2 K−1. This value is in the low range of the values determined for exfoliated flakes with other techniques such as Raman thermometry, which span an order of magnitude (0.44–50 MW m−2 K−1), and underlines the dispersion of measurements. The sensitivity to the in-plane thermal conductivity of supported MoS2 is very low, highlighting that the thermal boundary conductance is the key driver of heat dissipation for the MoS2 monolayer when it is not suspended. In addition, this work also demonstrates that SThM calibration using different thicknesses of SiO2, initially aimed at being used with bulk materials can be extended to 2D materials.
Flexible resistive switching device based on air-stable lead-free Cu3SbI6 perovskite film for nonvolatile memory application
Authors: Wang Yuchan , Yuan Yiming , Zhang Wenxia , Qi Fei , Zhang Nan , Liu Ting , Tang Xiaosheng
Published: June 2022

Resistive switching (RS) behavior of lead-free rudorffite perovskite Cu3SbI6 is explored for developing high performance flexible resistive switching random access memory (ReRAM) devices. The Cu3SbI6 based devices exhibit reproducible bipolar nonvolatile RS behaviors with low operating voltage (≤±0.6 V), stable endurance (≥400 cycles), and long data retention time (≥104 s). Moreover, the devices fabricated on flexible substrates show good electrical reliability and mechanical stability under different bending angles and consecutive bending cycles (103 times). A computational study method is used to reveal the mechanical stability of the Cu3SbI6 and the RS properties of the memory devices. More importantly, the Cu3SbI6 based devices exhibit no significant changes in RS behaviors after stored in ambient conditions for over 60 days. The results suggest that devices based on all-inorganic lead-free rudorffite perovskite materials have great potential for high performance, stable, and flexible ReRAM.
High-order Gundlach resonances at exceptional large voltages: Consequences for determining work functions
Authors: Schlenhoff A. , Kokkorakis G. C. , Xanthakis J. P.
Published: June 2022

We report a combined experimental and theoretical study of Gundlach resonances Un in scanning tunneling spectroscopy at constant current over an exceptional range of energy and number, typically tens of an eV and over thirty in order n. By performing (1) three-dimensional electrostatic calculations, (2) WKB quantum calculations of the current, and (3) one-dimensional solutions of the Schrödinger equation along the perpendicular line from the surface to the tip apex, we provide a theoretical understanding and prediction of the experimental U(n) curve. Unlike commonly assumed, the triangular potential well is not found to be a good approximation for the high-n states. We show that although the spectroscopy mode assures a constant electric field at the tip apex, this leads only for the intermediate resonance states (approximately 2<n<6) to reside in a linear potential between the tip and the surface. Whereas the low lying (n <6) states all lie approximately in the same quantum well, at higher tip-sample distances d and bias voltages V(d), the quantum well is no longer triangular but attains a curvature, which is d dependent. Each high-n state resides in its own well that can be well-approximated by a polynomial of second order. Hence, the range of Un to be analyzed in terms of spectroscopic positions needs to be chosen with great care when deducing surface work functions.
Role of the chiral spin configuration in field-free spin–orbit torque-induced magnetization switching by a locally injected spin current
Authors: An Suhyeok , Seo Hyeong-Joo , Baek Eunchong , Lee Soobeom , You Chun-Yeol
Published: June 2022

For deterministic magnetization switching by spin–orbit torque (SOT) in a perpendicular magnetic anisotropy system, an additional in-plane direction magnetic field is essential to break the lateral symmetry. Realizing chirality in a magnetic ordering system can be one approach for achieving asymmetry in the lateral direction for field-free magnetization switching. However, systematic analysis of the influence of the chiral spin system on deterministic switching is still scarce. We investigate the field-free SOT-induced magnetization switching by using a chiral spin configuration experimentally and theoretically with micromagnetic simulations. We designed a system in which only part of the ferromagnetic layer overlaps with the heavy metal layer in the Pt/Co/MgO structure. Therefore, a spin current exerts only on a local area of the ferromagnetic layer, which results in a Néel-type chiral spin configuration. The induced chiral spin configuration can be stabilized (or destabilized) depending on the sign of the interfacial Dzyaloshinskii–Moriya interaction and the direction of the current. The stabilized spin configuration plays a crucial role in the deterministic switching in the zero field. We expect our findings to widen the perspective on chirality-based all-electrical SOT device applications.
SOI-based micro-mechanical terahertz detector operating at room-temperature and atmospheric pressure
Authors: Froberger Kevin , Walter Benjamin , Lavancier Melanie , Peretti Romain , Ducournau Guillaume , Lampin Jean-François , Faucher Marc , Barbieri Stefano
Published: June 2022

We present a micro-mechanical terahertz (THz) detector fabricated on a silicon on insulator substrate and operating at room-temperature. The device is based on a U-shaped cantilever of micrometric size, on top of which two aluminum half-wave dipole antennas are deposited. This produces an absorption extending over the ∼2–3.5 THz frequency range. Due to the different thermal expansion coefficients of silicon and aluminum, the absorbed radiation induces a deformation of the cantilever, which is read out optically using a 1.5 μm laser diode. By illuminating the detector with an amplitude modulated, 2.5 THz quantum cascade laser, we obtain, at room-temperature and atmospheric pressure, a responsivity of ∼1.5×108 pm W−1 for the fundamental mechanical bending mode of the cantilever. This yields noise-equivalent-power of 20 nW/Hz at 2.5 THz. Finally, the low mechanical quality factor of the mode grants a broad frequency response of approximately 150 kHz bandwidth, with a thermal response time of ∼ 2.5 μs.
Optical properties of InGaN-based red multiple quantum wells
Authors: Hou Xin , Fan Shao-Sheng , Xu Huan , Iida Daisuke , Liu Yue-Jun , Mei Yang , Weng Guo-En , Chen Shao-Qiang , Zhang Bao-Ping , Ohkawa Kazuhiro
Published: June 2022

In this work, we present the characterization of red InGaN/GaN multiple-quantum-well (MQW) light-emitting diode structures. The optical properties of two MQW structures with different n-GaN underlayer thicknesses (4 and 8 μm) are studied and compared. The results of photoluminescence studies show that a thicker n-GaN layer is beneficial for obtaining higher In content for red MQWs. However, the sample with a thicker n-GaN layer has a poorer internal quantum efficiency, a larger full width at half maximum, and a shorter nonradiative recombination time, implying that there are stronger In-content fluctuations and more defects. Furthermore, red MQWs with higher In content are shown to exhibit more deep localized states. Our findings imply that in order to achieve high-efficiency InGaN MQWs for red emission, enhancing the uniformity of In-content distribution in the active region and decreasing nonradiative recombination centers are critical challenges.
Numerical simulations of cell sorting through inertial microfluidics
Authors: Esposito Giancarlo , Romano Salvatore , Hulsen Martien A. , D'Avino Gaetano , Villone Massimiliano M.
Published: June 2022

The dynamics of a cell suspended in a Newtonian liquid subjected to a pressure-driven flow at non-negligible inertia in cylindrical and square cross section microfluidic channels is studied through three-dimensional arbitrary Lagrangian–Eulerian finite-element numerical simulations. The cell is modeled through the neo-Hookean hyper-elastic constitutive equation, which can describe biological particles undergoing moderate deformations. The cell-to-channel relative dimension is fixed to 0.2, whereas the Reynolds number Re, measuring the relative importance of liquid inertial and viscous forces, and the elastic capillary number Cae, measuring the relative importance of liquid viscous stress and solid elastic stress, are varied by several orders of magnitude. In a cylindrical tube, the cell migrates transversally to the flow direction until reaching a radial equilibrium position depending on Re and Cae. Given Re, the softer the cell (i.e., the larger Cae) the closer its equilibrium position to the tube axis, thus allowing for the separation of healthy and diseased cells which have similar dimensions but different mechanical properties. In a channel with a square cross section, a much more complex dynamics is found. Depending on Re and Cae, the cell can either migrate to the channel centerline, to the closest median of the channel cross section (thus, four equilibrium positions can be identified due to symmetry), to the closest diagonal (again, four equilibrium positions), or to an intermediate position in between the median and the diagonal (eight equilibrium positions).
Designing, synthesizing, and modeling active fluids
Authors: Essafri Ilham , Ghosh Bappa , Desgranges Caroline , Delhommelle Jerome
Published: June 2022

We review recent advances in the design, synthesis, and modeling of active fluids. Active fluids have been at the center of many technological innovations and theoretical advances over the past two decades. Research on this new class of fluids has been inspired by the fascinating and remarkably efficient strategies that biological systems employ, leading to the development of biomimetic nano- and micro-machines and swimmers. The review encompasses active fluids on both the nano- and micro-scale. We start with examples of biological active systems before we discuss how experimentalists leverage novel propulsion mechanisms to power nano- and micro-machines. We then examine how the study of these far-from-equilibrium systems has prompted the development of new simulation methods and theoretical models in nonequilibrium physics to account for their mechanical, thermodynamic, and emergent properties. Recent advances in the field have paved the way for the design, synthesis, and modeling of autonomous systems at the nano- and micro-scale and opened the door to the development of soft matter robotics.
Non-isoplethic measurement on the solid–liquid–vapor equilibrium of binary mixtures at cryogenic temperatures
Authors: Raposa Shaelyn M. , Tan Sugata P. , Grundy William M. , Lindberg Gerrick E. , Hanley Jennifer , Steckloff Jordan K. , Tegler Stephen C. , Engle Anna E. , Thieberger Cecilia L.
Published: June 2022

We measured the solid–liquid–vapor (SLV) equilibrium of binary mixtures during experiments that alternated between cooling the mixture and injecting the more-volatile component into the sample chamber; thus, the composition of the mixture changed (non-isoplethic) throughout the experiment. Four binary mixtures were used in the experiments to represent mixtures with miscible solid phases (N2/CO) and barely miscible solid solutions (N2/C2H6), as well as mixtures with intermediate solid miscibility (N2/CH4 and CO/CH4). We measured new SLV pressure data for the binary mixtures, except for N2/CH4, which are also available in the literature for verification in this work. While these mixtures are of great interest in planetary science and cryogenics, the resulting pressure data are also needed for modeling purposes. We found the results for N2/CH4 to be consistent with the literature. The resulting new SLV curve for CO/CH4 shows similarities to N2/CH4. Both have two density inversion points (bracketing the temperature range where the solid floats). This result is important for places such as Pluto, Triton, and Titan, where these mixtures exist in vapor, liquid, and solid phases. Based on our experiments, the presence of a eutectic is unlikely for the N2/CH4 and CO/CH4 systems. An azeotrope with or without a peritectic is likely, but further investigations are needed to confirm. The N2/CO system does not have a density inversion point, as the ice always sinks in its liquid. For N2/C2H6, new SLV pressure data were measured near each triple point of the pure components.
Epitaxial buffer structures grown on 200 mm engineering substrates for 1200 V E-mode HEMT application
Authors: Vohra Anurag , Geens Karen , Zhao Ming , Syshchyk Olga , Hahn Herwig , Fahle Dirk , Bakeroot Benoit , Wellekens Dirk , Vanhove Benjamin , Langer Robert , Decoutere Stefaan
Published: June 2022

In this work, we demonstrate the epitaxial growth of a gallium-nitride (GaN) buffer structure qualified for 1200 V applications on 200 mm engineered poly-AlN substrates with hard breakdown >1200 V. The manufacturability of a 1200 V qualified buffer structure opens doors to high voltage GaN-based power applications such as in electric cars. Key to achieving the high breakdown voltage is careful engineering of the complex epitaxial material stack in combination with the use of 200 mm engineered poly-AlN substrates. The CMOS-fab friendly engineered poly-AlN substrates have a coefficient of thermal expansion (CTE) that closely matches the CTE of the GaN/AlGaN epitaxial layers, paving the way for a thicker buffer structure on large diameter substrates, while maintaining the mechanical strength of the substrates and reaching higher voltage operation.
Accelerating and improving deep reinforcement learning-based active flow control: Transfer training of policy network
Authors: Wang Yi-Zhe , Hua Yue , Aubry Nadine , Chen Zhi-Hua , Wu Wei-Tao , Cui Jiahuan
Published: June 2022

Deep reinforcement learning (DRL) has gradually emerged as an effective and novel method to achieve active flow control with outstanding performance. This paper focuses on exploring the strategy of improving learning efficiency and control performance of a new task using existing control experience. More specifically, the proximal policy optimization algorithm is used to control the flow past a circular cylinder using jets. The DRL controllers trained from the initialized parameter are able to obtain drag reductions of 8%, 18.7%, 18.4%, and 25.2%, at Re = 100, 200, 300, and 1000, respectively, and it takes more episodes to converge for the cases with higher Reynolds number, due to the increased flow complexity. Furthermore, the agent trained at high Reynolds number shows satisfied control performance when it is applied to the lower Reynolds number cases, which proves a strong correlation between the control policy and the flow patterns between the flows under different conditions. To better utilize the experience of the control policy of the trained agent, the flow control tasks with Re = 200, 300, and 1000 are retrained, based on the trained agent at Re = 100, 200, and 300, respectively. Our results show that a dramatic enhancement of the learning efficiency can be achieved; that is, the number of the training episodes reduces to be less than 20% of the agents trained with random initialization. Moreover, for each flow condition drag reduction approaches a significant level of 20.9%, 27.7%, and 36.1%, respectively. The great performance of the transfer training method of the DRL agent shows its potential on economizing the training cost and improving control effectiveness, especially for complex control tasks.
Wettability control on imbibition behavior of oil and water in porous media
Authors: Cheng Zhilin , Zhang Wentong , Ning Zhengfu , Dou Liangbin , Zhan Jie , Zhao Chuang
Published: June 2022

Wettability determines the spreading or adherence behavior of fluids at the solid surface and significantly influences the displacement and entrapment of multiphase fluids in porous media. The present study sets out to determine how wettability controls the imbibition physics of oil and water in a matrix–fracture medium. The displacement and distribution characteristics of fluids, the types of flow regimes, and the fluid morphology under various conditions were revealed in depth. The influences of wettability on oil recovery and energy conversion were analyzed. Finally, the application of the conventional scaling model to simulated imbibition data was also discussed. Results show that the imbibition front is complete and stable in a water-wet medium with the one-end open boundary condition. There are three flow regimes occurring in countercurrent imbibition, depending on the wettability and Ca (capillary number) situations. Increasing θ (contact angle, the affinity of wetting phase to the solid) or Ca can shift the flow pattern from the capillary regime to the capillary-viscous regime to the viscous regime. Additionally, the imbibition oil recovery is greatly affected by wettability, and a more water-wet state does not signify a larger oil recovery. There is a power-law relationship between the oil recovery and the fractal dimension of the nonwetting phase. On the other hand, we performed the energy conversion analysis in the strongly water-wet condition. The external work is positive for both the capillary-viscous and viscous regimes and declines with the decreased Ca. Oil recovery could be linked to the surface energy ratio to some degree, which is relevant to Ca. For the capillary regime, oil recovery is proportional to the final reduced surface energy and does not have an evident relationship with the dissipation energy ratio. Through scaling the recovery factor data vs time via the linear, the power-law, and the conventional models, we find that the conventional scaling model can be used to fit the data point, and the fitting performance is good when Ca is relatively high. However, the linear model is more appropriate when scaling the data in low Ca. Overall, our pore-scale simulation study could pave the way for a further step toward investigating other influencing factors on imbibition behaviors of fluids in more complex media like natural rock materials, which exhibit strong heterogeneity of wettability and pore structure.
Effects of different vegetation restoration types on soil hydro-physical properties in the hilly region of the Loess Plateau, China
Authors: Lyu Du , Yang Yahui , Zhao Wenhui , Xu Xiaoming , He Liang , Guo Jinwei , Lei Siyue , Liu Baoyuan , Zhang Xiaoping
Published: June 2022

Context Severe soil erosion in the Chinese Loess Plateau and the resulting high sediment yield of the Yellow River have been important research topics. Aims Understanding the impacts of vegetation types on soil hydro-physical properties is essential for understanding regional runoff-sediment changes, soil and water conservation, and revegetation. Methods Three main plantation covers of the study area [natural restoration grassland (NG), artificial Prunus armeniaca forest (AP), and artificial Hippophae rhamnoides shrubland (AH) with 15 years of restoration] and Sorghum bicolor agricultural land as control (CK), were selected to compare their soil hydro-physical properties and infiltration capacity in the soil profile. Key results The bulk density was lower, and soil organic matter (SOM), the proportion of macro-aggregates (>5 mm), mean weight diameter (MWD) of water-stable aggregates, and the initial infiltration and stable infiltration rate were higher in the AH plot compared to CK and the other two plots. The impacts of vegetation restoration on soil properties were mainly in the 0–60 cm layer. Infiltration rates changed mainly within 5 h and basically stabilised within 10 h, with even shorter times to reach stable infiltration in CK. The initial and stable infiltration rates were significant positively correlated (P < 0.05) with macro-aggregate content, MWD, and SOM. Conclusions The AH and AP had greater impacts on soil hydro-properties than NG. The AH had the greatest positive effect on soil hydro-properties and soil and water conservation functions. Implications This study provides practical references for vegetation restoration measures assessment on the Loess Plateau or other similar regions.