Vertical Scale Research Articles

Atomic Threshold Switch Based on All‐2D Material Heterostructures with Excellent Control Over Filament Growth and Volatility

AbstractThis report demonstrates that atomic‐level controlled formation/rupture of conductive filaments using all 2D heterostructure of hBN‐graphene is a feasible way to achieve excellent switching characteristics for ideal atomic switches. At a threshold voltage, graphene with stable ion migration routes forms a few atom comprising Ag filaments in hBN, which subsequently spontaneously break as the applied voltage lowers, resulting in optimal threshold switching behavior in an hBN atomic switch. The hBN‐graphene atomic threshold switch maintains volatile threshold switching behavior in a wide range of operating currents (10 nA – 100 µA), has an extremely high on/off ratio > 108, ultralow leakage current < 1 pA and exceptionally rapid switching (≈70 ns). Ionic transport of Ag+ through graphene can avoid the migration of excessive Ag atoms into single layer hBN during operations. As a result, the growth of conductive filaments is stable and protected from atomic defects widening in hBN. The novel findings of this study show that the scaling layer thickness can reach the physical limit of vertical thickness scaling to accommodate the single‐atom volume of silver (≈0.257 nm) when using hBN, and a single‐atom‐thick ionic barrier made of graphene can be used to control switching.

Decadal Observations of Internal Wave Energy, Shear, and Mixing in the Western Arctic Ocean

AbstractAs Arctic sea ice declines, wind energy has increasing access to the upper ocean, with potential consequences for ocean mixing, stratification, and turbulent heat fluxes. Here, we investigate the relationships between internal wave energy, turbulent dissipation, and ice concentration and draft using mooring data collected in the Beaufort Sea during 2003–2018. We focus on the 50–300 m depth range, using velocity and CTD records to estimate near‐inertial shear and energy, a finescale parameterization to infer turbulent dissipation rates, and ice draft observations to characterize the ice cover. All quantities varied widely on monthly and interannual timescales. Seasonally, near‐inertial energy increased when ice concentration and ice draft were low, but shear and dissipation did not. We show that this apparent contradiction occurred due to the vertical scales of internal wave energy, with open water associated with larger vertical scales. These larger vertical scale motions are associated with less shear, and tend to result in less dissipation. This relationship led to a seasonality in the correlation between shear and energy. This correlation was largest in the spring beneath full ice cover and smallest in the summer and fall when the ice had deteriorated. When considering interannually averaged properties, the year‐to‐year variability and the short ice‐free season currently obscure any potential trend. Implications for the future seasonal and interannual evolution of the Arctic Ocean and sea ice cover are discussed.

ReSQoV: A Scalable Resource Allocation Model for QoS-Satisfied Cloud Services

Dynamic resource provisioning is made more accessible with cloud computing. Monitoring a running service is critical, and modifications are performed when specific criteria are exceeded. It is a standard practice to add or delete resources in such situations. We investigate the method to ensure the Quality of Service (QoS), estimate the required resources, and modify allotted resources depending on workload, serialization, and parallelism due to resources. This article focuses on cloud QoS violation remediation using resource planning and scaling. A Resource Quantified Scaling for QoS Violation (ReSQoV) model is proposed based on the Universal Scalability Law (USL), which provides cloud service capacity for specific workloads and generates a capacity model. ReSQoV considers the system overheads while allocating resources to maintain the agreed QoS. As the QoS violation detection decision is Probably Violation and Definitely Violation, the remedial action is triggered, and required resources are added to the virtual machine as vertical scaling. The scenarios emulate QoS parameters and their respective resource utilization for ReSQoV compared to policy-based resource allocation. The results show that after USLbased Quantified resource allocation, QoS is regained, and validation of the ReSQoV is performed through the statistical test ANOVA that shows the significant difference before and after implementation.

Research on Comprehensive Evaluation of High-quality Development of China's Regional Manufacturing Industry

Promoting the high-quality development of the manufacturing industry is an inevitable choice under the background of the developme nt of my country's new era. The article focuses on the connotation of the high-quality development of the manufacturing industry and builds an evaluation index system for the high-quality development of the manufacturing industry from four dimensions: high-end, innovative, service-oriented, and green. , using the vertical and horizontal scale method to evaluate and analyze the high-quality development level of the manufacturing industry in 30 provinces and cities from 2010 to 2020. The results show that the high-quality development of the manufacturing industry in my country is unbalanced among regions, showing a trend of strength in the east and weakness in the west. Based on the empirical results, corresponding policy recommendations are put forward for different regions.

Bubbles and OB associations

Abstract Supernovae explosions (SNe) in a stratified interstellar disc can create large scale structures and outflows perpendicular to the disc. Their morphology and emission characteristics depend on interrelations between the number of exploded SNe, the ISM vertical scale height, the height above the ISM disc at which SNe are located, and the mid-plane density of ambient gas. When observed such out-of-plane gas structures do characterize properties of the driving SNe and reveal the presence of underlying stellar clusters. Even though the morphology and emission properties of such structures are sensitive to characteristics of ambient gas they might be used for rough estimates of the clusters’ mass.

Effect of Statistically Anisotropic Undrained Shear Strength on the Probability of Slope Failure

Due to large-scale geological deposition processes, slope structures are often stratified, which means that the spatial distribution of the parameters involved in slope reliability evaluation is statistically anisotropic. This paper studies the effect of the statistical anisotropy of undrained shear strength on the probability of slope failure (pf) based on the Monte Carlo simulation. The results show that for the horizontally layered slope, the larger the horizontal correlation scale of undrained shear strength (λx) is, the larger pf is, especially when λx is smaller than the slope length; for the vertically layered slope, the larger the vertical correlation scale (λy) is, the smaller pf is, especially when λy is smaller than the slope height. Additionally, the mechanism of the above results is discussed by analyzing the displacement distribution at different correlation scales. The findings indicate that in the reliability evaluation of undrained slopes in stratified structures, either underestimation of λx or overestimation of λy leads to an unconservative estimate of pf, resulting in an overestimation of the slope stability.

Dizziness in older persons at high risk of future hospitalization: prevalence, differences between those with and without dizziness, and effect of a proactive primary care intervention

BackgroundDizziness is a common reason for seeking care, and frequently affects older persons. The aims were to determine the prevalence of dizziness in older persons at high risk of hospitalization, to compare subjects with and without dizziness, and to examine the effects on dizziness of a proactive primary care intervention in comparison with conventional care after one year.MethodsData were derived from a prospective multicentre clinical trial in persons aged 75 and older and at high risk of hospitalization. A baseline questionnaire included demographic data, use of aids, questions about everyday physical activity and exercise, pain (intensity, frequency, and duration), activities of daily living measured using the ADL Staircase, and health-related quality of life measured using the EQ-5D-3L vertical visual analogue scale. Both at baseline and after one year, subjects were asked about dizziness, and those with dizziness answered the Dizziness Handicap Inventory – Screening version. Subjects in the intervention group were evaluated by a primary care team and when needed proactive care plans were established. Groups were compared using the Mann Whitney U-test or chi-squared test.ResultsOf the 779 subjects, 493 (63%) experienced dizziness. Persons with dizziness differed regarding sex, homecare service, aids, activities of daily living, health-related quality of life, physical activity, and pain. The intervention did not significantly reduce the level of dizziness.ConclusionsDizziness is common in vulnerable older persons, and individuals with dizziness differ in several respects. Further studies are needed employing more dizziness-specific assessment and individually tailored interventions.Trial registrationClinicalTrials.gov 170608, ID: NCT03180606.

Early stage diapirism in the Red Sea deep-water evaporites: Origins and length-scales

Rayleigh-Taylor models for diapirism predict that diapirs should develop with characteristic spacings, whereas other models predict varied spacings. The deep-water Miocene evaporites in the Red Sea provide a useful opportunity to quantify length scales of diapirism to compare with model predictions. We first review the stratigraphy of the uppermost evaporites in high-resolution seismic data, revealing tectonic growth stratigraphy indicating that halokinetic movements occurred while the evaporites were being deposited. In some places, movements continued after the Miocene evaporite phase. The S-reflection marking the top of the evaporites is an erosional surface, in places, truncating anticlines of layered evaporites. In others, reflections within the uppermost evaporites are conformable, suggesting a lack of erosion. The top of the evaporites therefore had relief at the end of the Miocene. We select for numerical analysis 14 long profiles of topography of the S-reflection. Variograms derived from them after detrending reveal minor periodicity, though with varied wavelength, and varied roughness of the surface. However, an average variogram computed from these profiles is nearly exponential, indicating that the evaporite surface is mostly stochastic with no uniform scale of diapirism. An exponential model fitted to that average variogram suggests a spatial range over which the S-reflection topography becomes decorrelated of 3 km, which is comparable with the mean vertical thickness of the evaporite body. Power spectra of the evaporite surface are flatter at long wavelengths, which we interpret as due to weakness of halite preventing large surface relief from developing. The results suggest only modest periodicity, so the Rayleigh-Taylor model does not explain deformation in the Red Sea evaporites studied here. Their topography may turn out to be useful for suggesting the vertical scales and lengthscales of relief to expect of early stages of other salt giants, such as that of the Santo Basin.

Hydrodynamics of warps in the local model of astrophysical discs

ABSTRACT We show how the local approximation of astrophysical discs, which is the basis for the well-known model of the shearing box, can be used to study many aspects of the dynamics of warped discs. In the local model, inclination of the orbit of a test particle, with respect to the reference orbit, corresponds to a vertical oscillation of the particle at the orbital frequency. Warping of a disc corresponds to a locally axisymmetric corrugation of the mid-plane of the disc that oscillates vertically at the orbital frequency, while evolution of the warp corresponds to a modulation of the complex amplitude of the vertical oscillation. We derive a conservation law for this amplitude that is the local equivalent of the conservation of angular momentum and therefore governs the evolution of the warp. For length scales that are long compared to the vertical scale height of the disc, the known non-resonant and resonant regimes of warp dynamics, including the diffusive and wave-like regimes of Keplerian discs, occur in the local model in the same way as in a global view of warped discs.

A systematic approach for horizontal and vertical scale up of sintered Ultra-High Temperature Ceramic Matrix Composites for aerospace – Advances and perspectives

Ultra-High Temperature Ceramic Matrix Composites (UHTCMCs) are the next generation composites developed for application in the harsh environment of aerospace. Qualification of these materials requires the manufacturing of demonstrators for testing in relevant environments, which in turn, requires to scale them up. This paper illustrates the systematic approach adopted for the scale-up of UHTCMCs based on carbon fibre reinforced zirconium diboride plus silicon carbide from laboratory to industrial scale dimensions. The scale-up process covered a period of three years and concerned an increase in diameter of ∼10 times (from 40 to 400 mm), and in thickness of ∼30 times (from 5 to 160 mm). Small-scale products were consolidated by hot pressing at ISTEC whilst larger samples were consolidated by an industrial spark plasma sintering facility (NanokerResearch, Spain). After each scale-up step, reproducibility of composition, microstructure and properties was carefully checked. Thanks to the homogenous fibre distribution and sapient dosing of secondary phases, composites with different diameters and thickness were successfully consolidated by both techniques with little adjustment of sintering parameters up to the maximum size of available industrial furnaces . The large discs produced allowed production of 170 mm long bars for tensile testing and large tiles for hypersonic wind tunnel tests . Thick samples were useful to machine complex shapes such as screws and nuts, vertical bars for characterization of properties along the composite thickness and nozzle demonstrators. • ZrB 2 -Cf composites were scaled-up 10 times in diameter, 30 times in thickness. • A manufact of UHTCMC material weighting 11 kg was produced for the first time. • The same mechanisms were efficient for scale-up in diameter and thickness. • Reproducible microstructure-properties were assessed from lab to industrial scale. • Large components such as plates, nozzle inserts, screw and nuts were fabricated.

The Beaufort Sea acoustic duct's variability and its impact on acoustic propagation using the mode interaction parameter

The Beaufort duct is a subsurface sound channel formed by cold Pacific Winter Water sandwiched between warmer Pacific Summer Water and Atlantic Water in the Western Arctic Ocean. This duct traps sound waves and allows them to travel long distances without losing energy to lossy interactions with sea ice and surface waves. This study quantifies Beaufort duct variability based on Canada Basin Acoustic Propagation Experiment (CANAPE) and Coordinated Arctic Acoustic Thermometry Experiment (CAATEX) oceanographic observations. Deterministic ocean features induce coupling between acoustic modes confined to the Beaufort duct and non-ducted modes by weakening the duct or causing it to take on an asymmetric form. A non-dimensional mode interaction parameter (MIP) can be defined using the acoustic frequency and the vertical and horizontal scales of sound speed perturbation to characterize coupling strength. It identifies three important wave propagation regimes: sudden approximation, adiabatic approximation, and maximum interaction regime (Colosi and Zinicola-Lapin, 2021). When the MIP between ducted and lossy modes is more and less than 1, strong and weak acoustic variability is predicted, respectively. Variability is high when the MIP between two ducted modes surpasses 1, but modei–mode interference patterns grow more complicated. Acoustic numerical simulations are used to demonstrate various effects.

Ratio Between Over‐Satellite Electron Content and Plasma Density Measured by Swarm: A Proxy for Topside Scale Height

AbstractIn‐situ plasma density (Ne) and Over‐Satellite Electron Content (OSEC) measured at Low‐Earth‐Orbit (LEO) are basic parameters for analyzing ionospheric plasma. In this study, we calculate the ratio of OSEC to Ne (OSEC‐to‐Ne ratio; α) measured by Swarm in the daytime topside, which is analogous to the traditional slab thickness of the ionosphere. Dependence of the α on latitude, local time, season, and solar activity generally agrees with the known climatology of vertical scale height (VSH) of the topside ionosphere. Hence, the α can be deemed a proxy for the VSH. Calibrated Swarm‐A and Swarm‐B data at two different altitudes further demonstrate that lower‐altitude Ne and α can reasonably estimate higher‐altitude Ne. In addition, a new method is proposed to estimate effective ion mass from the α and electron/ion temperature measured by Swarm. The estimates are broadly consistent with recent reports on topside ion composition. All these results demonstrate the usefulness of the α in constraining vertical profiles and composition of the topside ionosphere. Caveats for using the α are given, and possible directions of future improvement are discussed.

Numerical Simulation of Water Tank Circulation and Water Age Under Different Working Conditions

AbstractWith increasing real estate and apartment vacancy rates, the utilization rate of the water in water tanks is decreasing; this leads to an increase in the water age and deteriorates the water quality in water tanks. The general hydrostatic numerical model cannot simulate the flow field and water age of a water tank correctly because the horizontal scale of the water tank is equivalent to the vertical scale, and the vertical hydrostatic approximation assumption is no longer applicable. In this paper, the water age module is added to a three‐dimensional numerical model based on estuarine and coastal oceans, and a nonhydrostatic numerical model is developed to simulate and analyze the three‐dimensional flow field and the temporal and spatial variations in the water age of the water tank under different working conditions. The total water consumption and the effective volume of the water tank are the main factors affecting the water age, followed by the water level change range. The water age can be reduced to a lesser extent by setting the position of the inlet and outlet at a diagonal angle and adopting a larger inflow velocity. The distributions of the circulation and water age are mainly determined by the inlet in the influent process. There is no obvious dead water zone in the tank due to the strong disturbance, advection and diffusion in the secondary water supply process. The water age distribution in the water tank is mainly affected by advection, while diffusion plays a secondary role.

SLO-aware dynamic self-adaptation of resources

Cloud computing and Network Function Virtualization (NFV) are two complementary technologies. Virtual network functions (VNFs) provided by NFV are connected in the form of service function chains (SFCs) and typically hosted on the cloud. Dynamic resource adaptation in NFV-cloud settings remains a challenging research problem. VNF resources can be adapted by performing either vertical scaling (VS), horizontal scaling (HS), or Migration (M). Deciding on the optimum strategy among these three approaches (VS, HS, M) may face several challenges, including the dynamicity of the cloud environment; the sheer multiplicity of SFC topologies (e.g., linear, or non-linear SFCs); potentially conflicting optimization objectives, and the substrate network configuration. Considering the challenges introduced, we propose decision-making algorithms that make the best adaptation decisions for the SFCs dynamically, while balancing a set of cost functions, such as energy consumption, resource utilization, and Service Level Objective (SLO) violation. We first formulate the problem as an integer linear programming (ILP) model to compute the optimal solution. Then, because solving an ILP model is time-consuming, we adopt multi-objective metaheuristic algorithms based on Non-dominated Sorting Genetic Algorithm (NSGAII), Chemical Reaction Optimization (CRO), Binary Particle Swarm Optimization (NBPSO), and the combination CRO-NBPSO to solve this problem. Experimental results demonstrate the effectiveness of the proposed meta-heuristic algorithms in reducing the end-to-end latency while achieving performance similar to optimal solutions in terms of resource utilization and energy consumption.

Impact of the COVID-19 on the vertical distributions of major pollutants from a tower in the Pearl River Delta

The outbreak of the 2019 novel coronavirus (COVID-19) had a large impact on human health and socio-economics worldwide. The lockdown implemented in China beginning from January 23, 2020 led to sharp reductions in human activities and associated emissions. The declines in primary pollution provided a unique opportunity to examine the relationship between anthropogenic emissions and air quality. This study reports on air pollutant and meteorological measurements at different heights from a tall tower in the Pearl River Delta. These measurements were used to investigate the vertical scale response of pollutants to understand reductions in human activities. Compared to that in the pre-lockdown period (from December 16, 2019), the concentrations of surface layer nitric oxide (NOx), fine particulate matter (PM2.5), and daily maximum 8 h average ozone (MDA8O3) declined significantly during the lockdown by 76.8%, 49.4%, and 18.6%, respectively. Although the vertical profiles of NOx and O3 changed during the lockdown period, those of PM2.5 remained the same. During the lockdown period, there were statistically significant correlations between PM2.5 and O3 but not between PM2.5 and NOx at four heights, indicating that the main composition of PM2.5 have dramatically changed, during which the impact of NOx on PM2.5 became insignificant. Additionally, O3 concentrations were also insensitive to NOx concentrations during the lockdown, implying that O3 levels were more of a representative of regional background level. In this case, local photochemical formation is no longer a significant ozone source. This evidence suggests that it is possible to mitigation of PM2.5 and O3 levels simultaneously by significant reductions in anthropogenic emissions.

Atlantic equatorial deep jets in Argo float data

Abstract Equatorial deep jets (EDJ) are zonal currents along the equator in all three ocean basins that alternate in direction with depth and time. In the Atlantic below the thermocline, they are the dominant variability on interannual timescales. Observations of equatorial deep jets are available but scarce, given the EDJs’ location at depth, their small vertical scale and their long periodicity of several years. In the last few years, Argo floats have added a significant amount of measurements at intermediate depth. In this study we therefore revise estimates of the EDJ scales based on Argo float data. Mostly, we use velocity data at 1000 m depth calculated from float displacement, which yield robust estimates of the Atlantic EDJ period (4.6 years), amplitude distribution, phase distribution, zonal wavelength (146.7°), and meridional structure. We also show that the equatorial amplitude of the EDJs’ first meridional mode Rossby wave component (9.8 cm s−1) is larger than that of their Kelvin wave component (2.8 cm s−1). Additionally, we present a new estimation of the EDJs’ vertical structure throughout the Atlantic basin, based on an equatorial geostrophic velocity reconstruction from hydrographic Argo float measurements from depths between 400 and 2000 m. Our new estimates from Argo float data provide the first basin-wide assessment of the Atlantic EDJ scales, as well as having smaller uncertainties than estimates from earlier studies.

Separating Energetic Internal Gravity Waves and Small‐Scale Frontal Dynamics

AbstractOceanic fronts with lateral scales less than 20 km are now known to be one of the major contributors to vertical heat fluxes in the global ocean, which highlights their potential impact on Earth's climate. However, frontal dynamics with time scales less than 1 day, whose contribution to vertical heat fluxes is thought to be significant, are obscured by energetic internal gravity waves (IGWs). In this study, we address this critical issue by separating IGWs and frontal dynamics using an approach based on their respective vertical scales of variability. Results using a numerical model with a horizontal grid spacing of 500 m confirm that it is possible to recover frontal dynamics at short time scales as well as associated intense vertical velocities and vertical heat fluxes. This opens up new possibilities for a more accurate estimation of the vertical exchanges of any tracers between the surface and the ocean interior.

The crustal and uppermost mantle dynamics of the Tengchong–Baoshan region revealed by P-wave velocity and azimuthal anisotropic tomography

SUMMARY The Tengchong–Baoshan region (TBR) is located at the margin of the southeastern Tibetan Plateau (SETP) and is subject to the complex interaction among multiple tectonic blocks. Therefore, the TBR is approximate for investigating the mechanism responsible for the interaction among the SETP and its surrounding blocks. Based on eikonal equation-based seismic tomography, we obtain high-resolution P-wave velocity and azimuthal anisotropy at depths of 0–40 km beneath the TBR. We discover a large magma reservoir (with horizontal scale of ∼50 km and vertical scale of ∼15 km) in the middle-lower crust beneath the Tengchong volcanic zone, which is directly fed by hot materials from the uppermost mantle. We also detect a shallow magma chamber in the uppermost crust above the large reservoir. These magma reservoirs at different depths constitute a multiscale magma system. Furthermore, we observe a low-velocity belt beneath the Weixi–Qiaohou–Weishan and Nantinghe faults and postulate that it corresponds to lower crustal flow and hot mantle upwelling. Additionally, we infer that two M > 7.0 earthquakes that have occurred in Baoshan block nucleated in the transition zone between low- and high-velocity anomalies. Based on the azimuthal anisotropy tomography results, we consider that incoherent deformation in the crust causes the uneven accumulation of stress, which facilitated the occurrence of these two events. The 2021 Ms 6.4 Yangbi earthquake also occurred in the transition zone between low- and high-velocity anomalies. Based on the P-wave velocity tomography results, we suggest that hot material decreases the fault strength and leads to the instability of the fault.

Worst-case effect in bearing capacity of spread foundations considering safety factors and anisotropy in soil spatial variability

ABSTRACT Random field theory is currently the most important tool used when modelling spatial variabilities in soil properties. However, there are practical difficulties in indicating spatial correlation parameters, such as horizontal and vertical fluctuation scales. Therefore, the performed analyses touch upon the occurrence of the worst-case effect of the horizontal fluctuation scale. The random finite element (RFEM) approach is utilised to estimate probability distributions of the bearing capacity of a spread foundation. The analyses show that the observed location of the worst-case phenomenon is closely related to the adopted safety factor. Therefore, it is difficult to directly indicate the horizontal fluctuation scale for which the failure probability has the greatest value. Nevertheless, some general guidelines are formulated and proposed. These general rules can be applied to the two-dimensional bearing capacity problem.

Improving the Vertical Modeling of Tropospheric Delay

AbstractAccurate tropospheric delays from Numerical Weather Models (NWM) are an important input to space geodetic techniques, especially for precise real‐time Global Navigation Satellite Systems, which are indispensable to earthquake and tsunami early warning systems as well as weather forecasting. The NWM‐based tropospheric delays are currently provided either site‐specific with a limited spatial coverage, or on two‐dimensional grids close to the Earth surface, which cannot be used for high altitudes. We introduce a new method of representing NWM‐derived tropospheric zenith hydrostatic and wet delays. A large volume of NWM‐derived data is parameterized with surface values and additional two or three coefficients for their vertical scaling to heights up to 14 km. A precision of 1–2 mm is achieved for reconstructing delays to the NWM‐determined delays at any altitudes. The method can efficiently deliver NWM‐derived tropospheric delays to a broader community of space geodetic techniques.