bluuebunny/crossref_metadata_2025 huggingface dataset:
Advances in coherent coupling between magnons and acoustic phonons
Authors: Li Yi , Zhao Chenbo , Zhang Wei , Hoffmann Axel , Novosad Valentyn
Published: June 2021

The interaction between magnetic and acoustic excitations has recently inspired many interdisciplinary studies ranging from fundamental physics to circuit implementation. Specifically, the exploration of their coherent interconversion enabled via the magnetoelastic coupling opens a new playground combining straintronics and spintronics and provides a unique platform for building up on-chip coherent information processing networks with miniaturized magnonic and acoustic devices. In this Perspective, we will focus on the recent progress of magnon–phonon coupled dynamic systems, including materials, circuits, imaging, and new physics. In particular, we highlight the unique features such as nonreciprocal acoustic wave propagation and strong coupling between magnons and phonons in magnetic thin-film systems, which provide a platform for their coherent manipulation and transduction. We will also review the frontiers of surface acoustic wave resonators in coherent quantum transduction and discuss how the novel acoustic circuit design can be applied in microwave spintronics.
Modeling the thermalization of electrons in conditions relevant to atmospheric pressure He-O2 nanosecond pulsed discharges
Authors: Bieniek M. S. , Walsh J. L. , Hasan M. I.
Published: June 2021

The electron thermalization process is significant in nanosecond pulsed discharges due to the applied voltage pulse's short duration and rapid rise and fall times. In this contribution, a comparison was made between two approaches to modeling the electron kinetics of electron thermalization in atmospheric pressure helium plasma with an oxygen admixture. Modeling based on the direct solution of the local time-dependent electron Boltzmann equation was compared with modeling based on the commonly used but less general local mean energy approximation. For modeling based on the local time-dependent electron Boltzmann equation, a temporary faster decay in the population of electrons in the high energy tail and a slower decay in the population of intermediate energy electrons were observed while the electron swarm cooled from an average energy of above 8 eV, without an electric field present. During that period, the electron impact reaction rate coefficients of helium direct ionization and electronic excitation decreased by more than three orders of magnitude as compared to the modeling based on the local mean energy approximation. Global modeling of the evolution of plasma species densities in response to an electric field typical of atmospheric pressure pulsed discharges was performed with the two approaches to electron kinetics. Differences in the species densities were observed between the two approaches, with a 100% increase in the maximum density of electrons found with the modeling based on the local mean energy approximation.
Discrete Langevin-type equation for p-order persistent time series and procedure of its reconstruction
Authors: Czechowski Zbigniew
Published: June 2021

The stochastic discrete Langevin-type equation, which can describe p-order persistent processes, was introduced. The procedure of reconstruction of the equation from time series was proposed and tested on synthetic data. The approach was applied to hydrological data leading to the stochastic model of the phenomenon. The work is a substantial extension of our paper [Chaos 26, 053109 (2016)], in which the persistence of order 1 was taken into account.
Large-scale structures of turbulent Rayleigh–Bénard convection in a slim-box
Authors: Zhou Wen-Feng , Chen Jun
Published: June 2021

We report a numerical study of the large-scale structure of turbulent Rayleigh–Bénard convection (RBC) in a slim-box using direct numerical simulations. The simulations are performed in a rectangular cell of 1/6 depth-to-width ratio with the Rayleigh number from Ra=1×107 to 5×109 and Prandtl number equal to 0.7. It turns out that the large-scale circulation is driven by the jet flows, which consist of thermal plume clusters emitted from the conducting plate. The oblique impinging jet presents similar behavior for Ra. Moreover, the Reynolds number defined by the jet speed is approximated as a power law Rem∼Ra0.50. The oblique jet impinges onto the horizontal plate and develops into a wall jet. The similar flow patterns over the plate indicate the coherent motion of the wall jet. The wall jet presents a three-layer structure including the viscous sublayer, the mixing layer, and the bulk. The velocity in each layer has its characteristic parameters. We analyzed the turbulent kinetic energy and dissipation and obtained the scaling laws of the horizontal and vertical velocity fluctuations and the heights of their peaks. The thermal boundary layer and the heat transfer on the plate are investigated. The self-similarity of the thermal boundary layer solution is verified by boundary layer theory. Further analysis reveals that the Nusselt number on the conducting plate is possessed by an exponential law of the horizontal location, Nux=Num exp (−x̃), where Num is the maximum Nusselt number on the plate and x̃ is the normalized horizontal distance to the stagnation point. We derived a power law of the maximum heat transfer on the plate by scaling analysis, Num∼Ra0.2925, in agreement with the simulations. All results indicate that both the oblique impinging jet and the wall jet characterize the near-wall flow and the global heat transfer of turbulent RBC at moderate Rayleigh numbers.
Multi-mode resistive spectroscopy for precisely controlling morphology of extremely narrow gap palladium nanocluster array
Authors: Nakamura N. , Kashiuchi K. , Ogi H.
Published: June 2021

During the deposition of a metallic material on a substrate, a nanocluster-array structure with an extremely narrow gap is formed transiently at the transition between isolated clusters and the continuous film. It is known that the nanocluster array shows a unique electrical property different from that of isolated clusters and the continuous film. The electrical property of the nanocluster array changes significantly depending on its morphology, and precise control of the deposition time is indispensable to obtain a desired electrical property. However, the detection of the transition is not straightforward. To overcome this problem, we develop the multi-mode resistive spectroscopy. It evaluates the morphological change during deposition using resonant vibrations of a piezoelectric material and enables the fabrication of nanocluster arrays with a slightly different morphology. Palladium nanocluster arrays with different morphologies are fabricated using this method, and the availability of the multi-mode resistive spectroscopy is demonstrated by evaluating their electrical response to hydrogen gas.
High switching uniformity in HfOx-based memristors by adding polydopamine-derived Ag nanoparticles on the electrode
Authors: Song Yujie , Wang Xingsheng , Wu Qiwen , Wang Chengxu , Du Shuo , Zhang Lianbin , Miao Xiangshui
Published: June 2021

In this Letter, a Ti/HfOx/Pt memristor with a modified Ti electrode created by inserting polydopamine (PDA)/Ag nanoparticles (AgNPs) between the Ti electrode and functional layer is reported. This memristor exhibits a significant improvement in the uniformity of device parameters [including set voltage, reset voltage, high resistance state (HRS) resistances, low resistance state (LRS) resistances, endurance, and retention] compared to conventional memristors. The AgNPs embedded in PDA renders a reduced variability in HRS and LRS resistances from 47% to 7%, and 46% to 11%, respectively. By fitting Poole–Frenkel and Ohmic behavior models, the consistency of the conductive mechanism of the devices before and after modification has been proven, which is further enhanced through variable temperature tests and the simulation of electric field distribution. It is believed that AgNPs play a lightning rod role in guiding the growth of conductive paths; thus, by growing AgNPs in situ on PDA film on the Ti electrode, it reduces the parameter variability.
Prediction of three-phase relative permeabilities of Berea sandstone using lattice Boltzmann method
Authors: Li Sheng , Jiang Fei , Wei Bei , Hou Jian , Liu Haihu
Published: June 2021

Three-phase flows through a pore network of Berea sandstone are studied numerically under critical interfacial tension conditions. Results show that the relative permeability of each fluid increases as its own saturation increases. The specific interfacial length between wetting and nonwetting fluids monotonously decreases with increasing the saturation of intermediate-wetting fluid, while the other two specific interfacial lengths exhibit a nonmonotonous variation. As the wetting (nonwetting) fluid becomes less wetting (nonwetting), the relative permeability of wetting fluid monotonously increases, while the other two relative permeabilities show a nonmonotonous trend. Due to the presence of a spreading layer, the specific interfacial length between wetting and nonwetting fluids always stabilizes at a low level. As the viscosity ratio of wetting (nonwetting) to intermediate-wetting fluids increases, the relative permeability of wetting (nonwetting) fluid increases. With the viscosity ratio deviating from unity, the phase interfaces become increasingly unstable, leading to an increased specific interfacial length.
The effects of laser polarization and wavelength on injection dynamics of a laser wakefield accelerator
Authors: Ma Y. , Seipt D. , Hussein A. E. , Hakimi S. , Beier N. F. , Hansen S. B. , Hinojosa J. , Maksimchuk A. , Nees J. , Krushelnick K. , Thomas A. G. R. , Dollar F.
Published: June 2021

Here, we investigate the effects of laser polarization and wavelength on electron injection dynamics in a laser wakefield accelerator. During the ionization process, electrons gain residual momentum and kinetic energy via above threshold ionization, which has a strong dependence on laser polarization. A circularly polarized laser pulse results in a much higher residual momentum and kinetic energy gain for the ionized electrons compared with the linearly polarized case. This residual momentum results in particle injection because of the sensitivity of particle trapping to the initial conditions and enhanced the total injected beam charge in both experiments and particle-in-cell simulations. Due to the strong correlation of above threshold ionization with laser wavelength, in this work we extended the investigation to long wavelength (up to 20 μm) drive pulses using particle-in-cell simulations. Owing to the gain in kinetic energy, it may be expected that the charge trapped would consistently increase for circular polarization with increasing laser wavelength, but this was not observed. Instead, there are oscillations with wavelength in the relative trapped charge between linear and circular polarization cases, which arise because of ionization and heating effects on the plasma. Our studies highlight the complex interplay between several different physical effects, including injection regimes—above threshold ionization assisted injection, wave-breaking injection by carrier-envelope-phase effects and ionization injection—ionization gradient induced laser pulse evolution, and thermal modifications to the wake structure that need considering when extrapolating laser wakefield acceleration to different wavelength regimes.
On the progress of ultrafast time-resolved THz scanning tunneling microscopy
Authors: Tachizaki Takehiro , Hayashi Kan , Kanemitsu Yoshihiko , Hirori Hideki
Published: June 2021

Scanning tunneling microscopy combined with terahertz (THz) electromagnetic pulses and its related technologies have developed remarkably. This technology has atomic-level spatial resolution in an ultrahigh vacuum and low-temperature environment, and it measures the electrical dynamical behavior of a sample’s surface with femtosecond temporal resolution. In particular, it has been used to image the diffusion and relaxation dynamics of electrons in real time and real space and even instantaneously control molecular motions. In this Perspective, we focus on recent progress in research and development of ultrafast time-resolved THz scanning tunneling microscopy and its application to materials research.
A comprehensive assessment of empirical potentials for carbon materials
Authors: Qian Cheng , McLean Ben , Hedman Daniel , Ding Feng
Published: June 2021

Carbon materials and their unique properties have been extensively studied by molecular dynamics, thanks to the wide range of available carbon bond order potentials (CBOPs). Recently, with the increase in popularity of machine learning (ML), potentials such as Gaussian approximation potential (GAP), trained using ML, can accurately predict results for carbon. However, selecting the right potential is crucial as each performs differently for different carbon allotropes, and these differences can lead to inaccurate results. This work compares the widely used CBOPs and the GAP-20 ML potential with density functional theory results, including lattice constants, cohesive energies, defect formation energies, van der Waals interactions, thermal stabilities, and mechanical properties for different carbon allotropes. We find that GAP-20 can more accurately predict the structure, defect properties, and formation energies for a variety of crystalline phase carbon compared to CBOPs. Importantly, GAP-20 can simulate the thermal stability of C60 and the fracture of carbon nanotubes and graphene accurately, where CBOPs struggle. However, similar to CBOPs, GAP-20 is unable to accurately account for van der Waals interactions. Despite this, we find that GAP-20 outperforms all CBOPs assessed here and is at present the most suitable potential for studying thermal and mechanical properties for pristine and defective carbon.
High-repetition rate solid target delivery system for PW-class laser–matter interaction at ELI Beamlines
Authors: Condamine F. P. , Jourdain N. , Hernandez J.-C. , Taylor M. , Bohlin H. , Fajstavr A. , Jeong T. M. , Kumar D. , Laštovička T. , Renner O. , Weber S.
Published: June 2021

L3-HAPLS (High-repetition-rate Advanced Petawatt Laser System) at ELI (Extreme Light Infrastructure) Beamlines currently delivers 0.45 PW pulses (12 J in 27 fs) at 3.3 Hz repetition rate. A fresh target surface for every shot was placed at the laser focus using an in-house tape target system designed to withstand large laser intensities and energies. It has been tested for different material thicknesses (25 and 7.6 µm), while L3-HAPLS delivered laser shots for energies ranging from 1 to 12 J. A technical description of the tape target system is given. The device can be used in diverse geometries needed for laser–matter interaction studies by providing an ≈300° free angle of view on the target in the equatorial plane. We show experimental data demonstrating the shot-to-shot stability of the device. An x-ray crystal spherical spectrometer was set up to measure the Kα yield stability, while a GHz H-field probe was used to check the shot-to-shot electromagnetic pulse generation. Finally, we discuss short and mid-term future improvements of the tape target system for efficient user operation.
Slip behavior of high-density polyethylene at small shear stresses in the presence of esterified polyethylene glycol
Authors: Dehghani Samaneh , Hosseini Mahdi Salami , Behzadfar Ehsan
Published: June 2021

Viscoelastic instabilities in polymer melts can be mitigated using polymer processing aids (PPAs) that impose slip between melts and substrates. In this study, the effect of a newly synthesized esterified polyethylene glycol (PEG) on the slip behavior of a high-molecular-weight high-density polyethylene at small shear stresses was investigated. Rheological measurements were employed to capture the dependence of slip velocities on shear stress and calculate extrapolation lengths and friction coefficients. Our findings showed that the incorporation of PEG-based PPA increased slip velocities while an increase at temperature suppressed slip. At 190 °C, there was a strong slip zone at shear stresses smaller than 9 kPa for all samples with and without PEG. In this zone, the extrapolation length showed ascending and descending behavior while its values were almost constant beyond this zone. The incorporation of PEG-based PPA at 190 °C doubled the extrapolation length from 300 to 600 μm and amplified its variation in the first zone. The study of the slip behavior at 210 °C revealed that the samples did not experience the first zone. They showed a second zone with extrapolation lengths well below 100 μm, signifying the presence of a weak slip regime. This study highlights the importance of PPAs in altering the slip mechanisms for high-molecular-weight polymer melts.
Room temperature depinning of the charge-density waves in quasi-two-dimensional 1T-TaS2 devices
Authors: Mohammadzadeh A. , Rehman A. , Kargar F. , Rumyantsev S. , Smulko J. M. , Knap W. , Lake R. K. , Balandin A. A.
Published: June 2021

We report on the depinning of nearly commensurate charge-density waves in 1T-TaS2 thin films at room temperature. A combination of the differential current–voltage measurements with the low-frequency noise spectroscopy provides unambiguous means for detecting the depinning threshold field in quasi-2D materials. The depinning process in 1T-TaS2 is not accompanied by an observable abrupt increase in electric current—in striking contrast to depinning in the conventional charge-density-wave materials with quasi-1D crystal structure. We explained it by the fact that the current density from the charge-density waves in the 1T-TaS2 devices is orders of magnitude smaller than the current density of the free carriers available in the discommensuration network surrounding the commensurate charge-density wave islands. The depinning fields in 1T-TaS2 thin-film devices are several orders of magnitude larger than those in quasi-1D van der Waals materials. Obtained results are important for the proposed applications of the charge-density wave devices in electronics.
Muon measurements embolden the search for new physics
Authors: Middleton Christine
Published: June 2021

Evidence is mounting that the value of the particle’s anomalous magnetic moment cannot be predicted by the best-available theory.
Challenges in the development of sperm cryopreservation protocols for snakes
Authors: Young Carly , Ravida Nicole , Durrant Barbara
Published: June 2021

Snake populations are declining worldwide, but research devoted to the development of sperm cryopreservation techniques for this taxon is very limited. Spermatozoa were collected postmortem from snakes of four squamate families (Elapidae, Colubridae, Viperidae and Pythonidae). Viability assessment was performed before and after cryopreservation. Spermatozoa were extended in TES and Tris (TEST) yolk buffer with 12% dimethylsulfoxide (DMSO) or 12% glycerol and frozen at a rate of 0.3°C min−1. The sperm quality index (SQI), representing three viability parameters (motility, plasma membrane and acrosome integrity), was determined. Despite some species differences, glycerol was a more effective cryoprotectant for Colubridae, whereas DMSO provided greater cryoprotection for spermatozoa of members of the other three families.
Attention bias modification in drug addiction: Enhancing control of subsequent habits
Authors: Parvaz Muhammad A. , Malaker Pias , Zilverstand Anna , Moeller Scott J. , Alia-Klein Nelly , Goldstein Rita Z.
Published: June 2021

Significance

This study assessed whether habitual (drug-related) attentional processes can be disrupted by cognitive reappraisal, an adaptive emotion regulation strategy that is presumed to deploy prefrontal cortex–mediated cognitive control, in cocaine-addicted individuals. The novelty of the current study is in the multimethod integration of outcome measures (i.e., using objective psychophysiological measures such as the late positive potentials and gaze duration but also past behavior) and the focus on the down-regulation of spontaneous attention bias to drug-related cues presented outside of the volitional/motivated self-regulation cognitive reappraisal window, achieved using a task design that maximized robust detection of subtle trial-by-trial perturbations in drug cue reactivity in cocaine-addicted individuals.
Tungsten-182 evidence for an ancient kimberlite source
Authors: Nakanishi Nao , Giuliani Andrea , Carlson Richard W. , Horan Mary F. , Woodhead Jon , Pearson D. Graham , Walker Richard J.
Published: June 2021

Significance

Kimberlites are igneous rocks derived from deep mantle sources. Recent studies have suggested that certain kimberlites originated from a mantle source with relatively primitive chemical composition that was created by early Earth processes. We present W isotope data for a global suite of kimberlites with variable formation ages and find their mantle source(s) to be characterized by
182
W/
184
W averaging ∼6 ppm lower than the upper mantle ratio. This result is consistent with derivation of some kimberlites from one or more early formed mantle reservoirs. The low
182
W/
184
W of these kimberlites is indicative of an ancient mantle source modified by some form of core–mantle interaction, an early silicate fractionation event, an overabundance of late-accreted materials, or a combination of these.
A phage mechanism for selective nicking of dUMP-containing DNA
Authors: Mahata Tridib , Molshanski-Mor Shahar , Goren Moran G. , Jana Biswanath , Kohen-Manor Miriam , Yosef Ido , Avram Oren , Pupko Tal , Salomon Dor , Qimron Udi
Published: June 2021

Significance

Studying the interactions of bacterial viruses (phages) with their bacterial hosts may lead to better understanding of bacterial mechanisms and consequently enable better manipulation of bacterial pathogens. In this study, we characterized the activity of a protein from phage T5, called T5.015. This protein binds to another protein, Ung, and uses its activity to selectively cleave dUMP-containing DNA. Such cleavage of the bacterial DNA stops bacterial DNA replication and also prevents bacterial division. Presumably, the phage DNA is protected from this activity as Ung does not act on the phage DNA, probably due to lower incorporation of the Ung substrate, dUMP. We believe that the findings are general to many phages and reveal a mechanism of self-versus-foreign DNA discrimination.
The effect of mass shootings on daily emotions is limited by time, geographic proximity, and political affiliation
Authors: Sharkey Patrick , Shen Yinzhi
Published: June 2021

Significance

Our study provides causal evidence of how a mass shooting affects the emotions of residents throughout the city and state where the event occurred. We found that mass shootings have a strong impact on the emotions of individuals, but the impact is politicized, limited to individuals living within the town or city where the incident occurs, and fades within a week of the incident. The findings provide evidence on the full emotional toll of mass shootings while also offering insights into the link between mass shootings and gun politics.
Evolution of single gyroid photonic crystals in bird feathers
Authors: Saranathan Vinodkumar , Narayanan Suresh , Sandy Alec , Dufresne Eric R. , Prum Richard O.
Published: June 2021

Vivid, saturated structural colors are conspicuous and important features of many animals. A rich diversity of three-dimensional periodic photonic nanostructures is found in the chitinaceous exoskeletons of invertebrates. Three-dimensional photonic nanostructures have been described in bird feathers, but they are typically quasi-ordered. Here, we report bicontinuous single gyroid β-keratin and air photonic crystal networks in the feather barbs of blue-winged leafbirds (
Chloropsis cochinchinensis sensu lato
), which have evolved from ancestral quasi-ordered channel-type nanostructures. Self-assembled avian photonic crystals may serve as inspiration for multifunctional applications, as they suggest efficient, alternative routes to single gyroid synthesis at optical length scales, which has been experimentally elusive.
Assisting translations in border crossing
Authors: Loogus Terje , van Doorslaer Luc
Published: June 2021

This contribution explores the position of translation policy and its connection to translation flows in translation studies research. Power relationships (among languages, cultures, etc.) are essential when assessing and interpreting translation flows. Despite the hyper-centrality of English, other countries and language areas develop cultural policies to export their own literature through translation. The case study furnished here deals with the state agents responsible for the literary translation policy of Estonia, viz., the Estonian Literature Centre and the Traducta translation grants of the Estonian Cultural Endowment (Eesti Kultuurkapital). The statutes of the Traducta program, including the selection criteria, express an instrumental view on translation that is partly in conflict with the findings of modern translation studies. The data on the awards of the Traducta program not only confirm that the publishing of a translation often depends on the additional financial support for the program, but also highlight the significant differences between different target language areas, in a complex interplay of economic factors with elements of cultural image-building and geographical proximity.
Mikania micrantha (bitter vine).
Authors: Day Michael
Published: June 2021

M. micrantha is a fast growing vine, native to Central and South America. It was intentionally introduced into a number of countries and has since become a major weed in Southeast Asia and the Pacific and is still extending its range. However, it has not yet been recorded in Africa. Once established, M. micrantha can quickly smother other vegetation, including native trees, plantation species and agricultural crops, killing plants and/or decreasing yield and biodiversity. In Nepal, the vulnerable greater one-horned rhinoceros is under threat as M. micrantha outcompetes plant species on which it browses. Control of this species is difficult as it produces are large number of seed, can readily shoot from runners and suckers and can regenerate from stem fragments. This species has been the target of a biological programme in many countries.
The effect of amplification on cortical synchrony in children with auditory neuropathy spectrum disorder
Authors: Cardon Garrett , Sharma Anu
Published: June 2021

Objective

The benefit of hearing aids as a clinical intervention strategy for children with Auditory Neuropathy Spectrum Disorder (ANSD) remains controversial. The goal of this study was to determine whether amplification through hearing aid use increased cortical phase synchrony in children with ANSD.

Design

Using inter-trial coherence (ITC) of the EEG signal as a measure of cortical phase-locking, we examined differences in cortical phase synchrony in children with ANSD using both cross-sectional and longitudinal designs.

Study Sample

Participants in the cross-sectional and longitudinal portions of the study included 58 and 16 children with clinical diagnoses of ANSD, respectively.

Results

Results in the cross-sectional portion of the study revealed no significant difference in ITC between unaided and aided children. Overall, longitudinal data revealed no significant increase in ITC over time with hearing aid use. However, half of the subjects in the longitudinal sample showed a significant decrease in ITC from the unaided to the aided conditions.

Conclusions

Overall, our results suggest that hearing aids may not be a beneficial intervention strategy for increasing cortical neural synchrony in all cases of ANSD and that amplification may actually reduce cortical phase-locking in some children with ANSD. The clinical implications of these findings are discussed.
Monolayer MoS2 photodetectors with a buried-gate field-effect transistor structure
Authors: Li Yuning , Li Shasha , Sun Jingye , Li Ke , Liu Zewen , Deng Tao
Published: June 2021

Unlike zero-bandgap graphene, molybdenum disulfide (MoS2) has an adjustable bandgap and high light absorption rate, hence photodetectors based on MoS2 have attracted tremendous research attention. Most of the reported MoS2 photodetectors adopted back-gate field-effect transistor (FET) structure due to its easy fabrication and modulation features. However, the back-gate FET structure requires very high gate voltage up to 100 V, and it is impossible to modulate each device in an array with this structure independently. This work demonstrated a monolayer MoS2 photodetector based on a buried-gate FET structure whose experimental results showed that both the electrical and photoelectrical properties could be well modulated by a gate voltage as low as 3 V. A photoresponsivity above 1 A W−1 was obtained under a 395 nm light-emitting diode light illumination, which is over 2 orders of magnitude higher than that of a reported back-gate photodetector based on monolayer MoS2 (7.5 mA W−1). The photoresponsivity can be further improved by increasing the buried gate voltage and source-drain voltage. These results are of significance for the practical applications of MoS2 photodetectors, especially in the low voltage and energy-saving areas.
Optical cycling of AlF molecules
Authors: Hofsäss S , Doppelbauer M , Wright S C , Kray S , Sartakov B G , Pérez-Ríos J , Meijer G , Truppe S
Published: June 2021

Aluminium monofluoride (AlF) is a promising candidate for laser cooling and trapping at high densities. We show efficient production of AlF in a bright, pulsed cryogenic buffer gas beam, and demonstrate rapid optical cycling on the Q rotational lines of the A
1Π ↔ X
1Σ+ transition. We measure the brightness of the molecular beam to be >1012 molecules per steradian per pulse in a single rotational state and present a new method to determine its velocity distribution in a single shot. The photon scattering rate of the optical cycling scheme is measured using three different methods, and is compared to theoretical predictions of the optical Bloch equations and a simplified rate equation model. Despite the large number of Zeeman sublevels (up to 216 for the Q(4) transition) involved, a high scattering rate of at least 17(2) × 106 s−1 can be sustained using a single, fixed-frequency laser without the need to modulate the polarisation. We deflect the molecu-lar beam using the radiation pressure force and measure an acceleration of 8.7(1.5) × 105 m s−2. Losses from the optical cycle due to vibrational branching to X
1Σ+, v″ = 1 are addressed efficiently with a single repump laser. Further, we investigate two other loss channels, parity mixing by stray electric fields and photo-ionisation. The upper bounds for these effects are sufficiently low to allow loading into a magneto‐optical trap.
Maximizing the capture velocity of molecular magneto-optical traps with Bayesian optimization
Authors: Xu S , Kaebert P , Stepanova M , Poll T , Siercke M , Ospelkaus S
Published: June 2021

Magneto-optical trapping (MOT) is a key technique on the route towards ultracold molecular ensembles. However, the realization and optimization of magneto-optical traps with their wide parameter space is particularly difficult. Here, we present a very general method for the optimization of molecular magneto-optical trap operation by means of Bayesian optimization. As an example for a possible application, we consider the optimization of a calcium fluoride MOT for maximum capture velocity. We find that both the X
2Σ+ to A
2Π1/2 and the X
2Σ+ to B
2Σ+ transition to allow for capture velocities with 24 m s−1 and 23 m s−1 respectively at a total laser power of 200 mW. In our simulation, the optimized capture velocity depends logarithmically on the beam power within the simulated power range of 25 to 400 mW. Applied to heavy molecules such as BaH, BaF, YbF and YbOH with their low capture velocity MOTs it might offer a route to far more robust MOT.
Common failures and solutions of check valve in gathering and transportation of produced crude oil
Authors: Zhiqiang Ma , Lili Guo , Tianlei Tang , Xiaoyong Yang , Fengying Zhang , Weiei Niu
Published: June 2021

In view of the problems in pumping wells in the No. 4 Oil Production Plant of PetroChina Huabei Oilfield Company, such as frequent failures of check valves in daily production, long shut-down time during maintenance, impact on crude oil production and high safety risk during maintenance, a new type of double-control check valve has been invented. This check valve has the dual functions of ordinary lift check valve and stop valve, which avoids the unsafety in the operation process, improves the well opening time rate of pumping wells, and has the advantages of simple operation, long service life, simple structure, convenient repairing and recycling, and considerable procurement cost is saved.
Study of Intelligent Unmanned Aerial Vehicle Delivery System
Authors: Tang Benping , Huang Jingde , Jiang Chenbo
Published: June 2021

In view of the terminal distribution link that has several shortcomings in the whole logistics chain such as the highest cost, the lowest efficiency and the most serious pollution, a kind of intelligent machine nest hub in this thesis, which carries out the analysis on the working principle of the machine nest hub system. In the meantime, the structure composition and control system of the machine nest hub is also designed. Based on the system designed in this thesis, it can enlighten the uninterrupted unmanned and automatic operation of the package delivery assembly end of UAV, and is able to handle the huge growth of orders in an effective way, so as to make the express delivery of UAV become more efficient and convenient.
Optimal vehicle trajectory planning scheme considering passengers’ comfort for advanced driving assistance
Authors: Gao Wenjia , Liu Haiqing , Teng Kumin , Rai Laxmisha
Published: June 2021

Speed guidance is a significant application in the driver assistance system or driverless automated system. Considering passengers’ comfort under different road conditions, this paper proposes an optimal vehicle speed trajectory planning strategy using the nonlinear programming solution method. In this method, the Pearl curve is taken as the basic model to describe the time-interval characteristics so that the speed and acceleration variation can be further obtained. Taking the weighted dimensionless average accelerated speed and vehicle travelling time as optimal objective, and the speed limit of intersection, speed limit of section, the position of the intersection, the maximum acceleration and deceleration rates, and the arrival time at the downstream intersection as constraints, a multi-variable and single-objective optimization model is built and calculated using Genetic Algorithm after discretization process of the original continuous acceleration variation curve. Results from case study shows that the proposed method presents substantial performance in planning a vehicle trajectory with optimal comfort on the basis that the vehicle arrives the downstream intersection as early as possible.
Construction of Open-pit Mine Environmental Monitoring System Based on Wireless Sensor Network
Authors: He Yuanrong , Nie Dewei , Wan Qianjin , Hang Lu
Published: June 2021

Green mining in mines should be combined with the emerging new technologies and methods to collect, store and display mine environmental data, so as to achieve the balance between mine economic benefits and environmental protection. In this paper, low power sensor nodes are deployed on a large scale in mines, which is based on LoRaWAN protocol wireless sensor network to build mine environment monitoring system of internet of things. Energy collection, energy management and storage of monitoring nodes are designed to realize self-sufficiency of power supply of monitoring nodes. The single chip microcomputer of the monitoring node reads the sensor data and sends it to the gateway and server, and then the client application program realizes data storage and display of mine monitoring node position, rainfall, PM2.5, temperature and humidity in two dimensions of time and space.
Research on Edge Computing Security Defense of Information Energy System
Authors: Jiang Jian , Li Jian , Chen Juan
Published: June 2021

Mobile Edge Computing (MEC) can effectively solve the problem of heavy backhaul link load and the long delay in traditional networks by further extending the telecom cellular network to other wireless access networks. However, because MEC nodes have abundant computing resources, communication resources, and storage resources, they carry the sensitive data storage, communication applications, and computing services of multiple enterprises. Once the attacker controls the edge nodes, they can use the edge nodes for further horizontal or Vertical attacks will seriously damage the confidentiality, availability, and integrity of applications, communications, and data, and will bring a wide range of new security threats to users and society. At the same time, MEC nodes are often deployed in unattended computer rooms, and there are multiple operators and responsible parties in the safety life cycle, which brings more challenges to physical safety protection and safe operation management. Based on the analysis of the security threats faced by mobile edge computing, the key problems, and challenges faced by mobile edge computing are summarized and expounded because of four different security subjects, namely, device security, application security, data security, and management security, and the existing security solutions are summarized.
Research on the summer meteorological support method of Yan Liang Airport for flight test
Authors: Zhang Ying , Ni Hongbo , Ni Ping , Yan Wenhui
Published: June 2021

Based on the demand of the aircraft flight test of wet braking distance, wiper function and high temperature subject flight test on the meteorological conditions. The surface meteorological observations of Yan Liang Airport were used to statistically analysis the characteristics of summer precipitation and high temperature weather. Based on the demand of the flight test management, organization and command department to implement the airborne meteorological radar detection performance flight test, formulate the risk prevention plan of thunderstorm and other strong convective weather to ensure the safety of flight test. The surface meteorological observations of Yan Liang Airport and Doppler weather radar detection data of Xi’an Jing Yang Station were used to statistically analysis the characteristics of summer thunderstorm weather at Yan Liang Airport and airspace. In recent years, it has provided strong technical support to ensure the quality, efficiency, progress and safety of the flight test.
Analysis on the Causes of a Weather Forecast Mistake in Yan Liang Airport
Authors: Zhang Ying , Qiao Danyang , Ni Hongbo , Cong Dongyang , Wang Zelin
Published: June 2021

Using the conventional weather maps and the T639 model numerical forecast products provided by Micaps system, we re-analyzed and diagnosed the precipitation weather process at Yan Liang Airport on May 26, 2018, and analyzed the reasons for the error in the 24-hour weather forecast on May 25. The analysis shows that the upper trough lines are distributed in the north and south, and the plateau low trough on the south side develops into a low vortex. With better water vapor conditions, the Changjiang-Huaihe shear line develops vigorously. When the colder air from the north-west meets the warm and humid airflow of the Changjiang-Huaihe shear line, the low vortex replenishes sufficient water vapor, and the floating dust brings abundant condensation nuclei to facilitate precipitation. During the whole process, the weather system moved slower than expected, but the weather process produced was more intense.
Influence of Test Condition on Rheological Property of Asphalt Combined Binder
Authors: Wang Shujie , Zhang Peng , Jiang Longsong , Lv Wei , Chen Lin , Wen Xiaobo
Published: June 2021

In order to study the influence of test condition on rheological property of asphalt combined binder, the paper uses five kinds of filler-bitumen ratio and different temperature condition.by the rheological test, it studies the asphalt combined binder on n the high-low temperature and fatigue performance. The result indicates that mineral powder can strength the high temperature performance, but it is bad for low temperature performance and fatigue performance; when test temperature is more higher, it’s high temperature performance and fatigue performance weaker, but it’s low temperature performance strength; co nsidering the high-low temperature and fatigue performance, it suggests the reasonable filler-bitumen ratio range is 0.8-1.0.
Application Analysis of Conductivity in Drinking Water Quality Analysis
Authors: Xianhong Yang , Shijun Liang , Jian Hu , Jie Xia
Published: June 2021

Water is the source of life, people take food as the sky, and food takes water first. With the discharge of industrial waste water, urban and rural domestic sewage and the increasing consumption of pesticides and fertilizers, many drinking water sources have been polluted, and the pollutant content in water has seriously exceeded the standard, which makes it difficult to guarantee the drinking water quality and hygiene of urban and rural residents who directly drink surface water and shallow groundwater. Classical wet chemical analysis method can only use different methods to determine parameters individually, and it has low sensitivity, many interferences and lengthy steps. According to the calculation method of conductivity in water quality analysis, this paper introduces the coincidence degree between measured conductivity and calculated conductivity, and the principle and practical application of taking the correlation between conductivity and total ion as quality control method.
Research on the versatility of Arctic marine nuclear power plant
Authors: Zhang Hao
Published: June 2021

Research on the versatility of nuclear power plants can increase the utilization rate of nuclear power plants and reduce the development cycle and cost. By comparing the power requirements of Russian nuclear power icebreakers, polar transport ships, and floating nuclear power plants, and combining the development status of Russian marine reactor devices and steam turbine generator sets, the analysis shows that marine nuclear power plants can be based on low (38tMW), The three-level benchmark reactor devices of medium (175tMW) and high (350tMW) and the two-level benchmark steam turbine power plants of low (6∼8 eMW) and medium (35-40 eMW) are designed for multi-scheme combination.
Test and research on red mud used in bauxite washing mud solidification
Authors: Bin Chen , Guoqiang Chen , Yibin Zhu , Wenlong Zhai
Published: June 2021

Bauxite washing mud is the high water content and strong fluidity material. After being dehydrated to water content of less than 40% with dehydrating agent, it is still in a flow-plastic state. In order to eliminate the potential safety hazards of washing mud pond, it can be solidified. In order to solidify Pingguo bauxite washing mud, Preparated of curing agent with red mud, cement, fly ash and desulfurization gypsum, then added into the washing mud at a weight ratio of 10% of the dry amount of the washing mud. This study shown that after adding curing agents, the water content of the washing mud is further reduced, the liquid limit and plastic limit are further increased, the particle size is increased, and the plastic state is changed to a hard state, which greatly reduces the safety hazards of the washing mud pond. Through the screening test of curing agent, this study found that the reasonable and effective curing agent formula is: 15% fly ash, 25% cement, 15% gypsum, 45% red mud, the liquid limit index of the cured material is reduced to -0.27, which is in a hard state, the clay washing mud was changed to clay loam, which is suitable for dry tailings storage.
Prediction of the growth of fungal communities in different environments: A GomPertz model approach
Authors: Yang Fan
Published: June 2021

The growth of fungal community is closely related to the environment. In order to study the effect of environmental change on fungi community, we first assume that global warming is the main trend of atmospheric change and assess the impact of this trend with Winters method and ARIMA model. Next, we improve the GomPertz model by considering temperature and humidity to formulate a fungus-environment model. Finally, we predict the evaluation trend of fungi communities and verify the above model in three different environments: ranging from arid to tropical rain forest. It can be concluded that in long-term, temperature has greater influence on the growth of fungi than humidity, which can somehow compensate for the lack of humidity. Therefore, fungi with better temperature tolerance will have relative advantage in the population.
Storage capacity and learning capability of quantum neural networks
Authors: Lewenstein Maciej , Gratsea Aikaterini , Riera-Campeny Andreu , Aloy Albert , Kasper Valentin , Sanpera Anna
Published: June 2021

We study the storage capacity of quantum neural networks (QNNs), described by completely positive trace preserving (CPTP) maps acting on an N-dimensional Hilbert space. We demonstrate that attractor QNNs can store in a non-trivial manner up to N linearly independent pure states. For n qubits, QNNs can reach an exponential storage capacity,

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, clearly outperforming standard classical neural networks whose storage capacity scales linearly with the number of neurons n. We estimate, employing the Gardner program, the relative volume of CPTP maps with M ⩽ N stationary states and show that this volume decreases exponentially with M and shrinks to zero for M ⩾ N + 1. We generalize our results to QNNs storing mixed states as well as input–output relations for feed-forward QNNs. Our approach opens the path to relate storage properties of QNNs to the quantum features of the input–output states. This paper is dedicated to the memory of Peter Wittek.