Smoothing Scale Research Articles

Influence of mesoscale sea‐surface temperature structures on the Mediterranean cyclone Ianos in convection‐permitting simulations: Contributions of surface warming and cold wakes

AbstractThis study examined the influence of mesoscale sea‐surface temperature (SST) structures and warming on the tropical‐like cyclone Ianos. The controlling mechanisms were investigated using a set of sensitivity experiments with the non‐hydrostatic weather research and forecasting model. A simulation forced by a high‐resolution SST field from the mesoscale eddy‐resolving HYCOM reanalysis (CTRLH) performed better than a simulation forced by a coarse‐resolution SST field from Optimum Interpolation Sea Surface Temperature (OISST) in terms of precipitation, wind intensity, and landfall location. The suppression of mesoscale SST variability affected the cyclone's intensity, its path, and associated processes. This effect depends on the nature of the anomalies (cold/warm). The suppression of mesoscale SST forcing intensified wind and precipitation in the presence of cold anomalies, leading to a northwestward shift of the storm's path during its mature phase. The magnitude of these changes varied with the scale of smoothing (mesoscale SST). Compared to the CTRLH simulation, a simulation in which a 60‐km smoothing filter was applied to the SST field resulted in a cyclone centered slightly to the west (or delayed by 3–6 hr), which was further shifted to the west (or delayed) when the smoothing filter was increased to 150 km. The intensification of wind and precipitation may be associated with the reduction in the storm's cold wake, which would lead to enhanced turbulent fluxes and increased atmospheric water vapor. These results highlight the role of small‐scale air–sea interaction processes that could have a strong impact on Mediterranean cyclones' path and intensity.

Analysis of an iterative reconstruction method in comparison of the standard reconstruction method

ABSTRACT We present a detailed analysis of a new iterative density reconstruction algorithm. This algorithm uses a decreasing smoothing scale to better reconstruct the density field in Lagrangian space. We implement this algorithm to run on the quijote simulations, and extend it to (a) include a smoothing kernel that smoothly goes from anisotropic to isotropic, and (b) a variant that does not correct for redshift space distortions. We compare the performance of this algorithm with the standard reconstruction method. Our examinations of the methods include cross-correlation of the reconstructed density field with the linear density field, reconstructed two-point functions, and BAO parameter fitting. We also examine the impact of various parameters, such as smoothing scale, anisotropic smoothing, tracer type/bias, and the inclusion of second order perturbation theory. We find that the two reconstruction algorithms are comparable in most of the areas we examine. In particular, both algorithms give consistent fittings of BAO parameters. The fits are robust over a range of smoothing scales. We find the iterative algorithm is significantly better at removing redshift space distortions. The new algorithm will be a promising method to be employed in the ongoing and future large-scale structure surveys.

Spatial resolution of sea surface temperature observed by AMSR2 on GCOM-W satellite

ABSTRACT This study developed a method to evaluate the effective spatial resolution of sea surface temperature (SST) data produced from observations of a microwave radiometer on satellites. The method was applied to 7-year SST data from the Advanced Microwave Scanning Radiometer 2 (AMSR2) on the Japan Aerospace Exploration Agency’s (JAXA) Global Change Observation Mission-Water (GCOM-W) satellite. JAXA has produced three SST products from AMSR2 observations: standard SST, 10-GHz SST, and multi-band SST. They differ in spatial resolution because the frequency used to retrieve the SST has different footprint sizes, although the resolution has not been evaluated so far. We utilized high-resolution infrared SST data from the geostationary meteorological satellite Himawari-8. The Himawari SST was spatially smoothed by a Gaussian function to identify the smoothing scale that most accurately reproduces the AMSR2 SST gradient fields in the same area and time. The similarities between the Himawari and AMSR2 SST gradient fields were assessed using three metrics. The correlation coefficient provided a stable and robust estimate against the noise included in the AMSR2 SSTs. As a result, the effective resolution was estimated at 67 km for the standard SST, 52 km for the 10-GHz SST, and 63 km for the multi-band SST. These are all larger than the nominal resolution expected from the AMSR2 footprint size. The 10-GHz and multi-band SSTs had significantly higher resolutions than the standard SST.

On the (Higher Multipoles) Variance Asymmetry in the Cosmic Microwave Background

We have studied the cosmic microwave background (CMB) map looking for features beyond cosmological isotropy. We began by tiling the CMB variance maps (which are produced by different smoothing scales) with stripes of different sizes along the most prominent dipole direction. We were able to confirm previous findings regarding the significance of the dipole. Furthermore, we discovered that some of the higher multipoles exhibit significance comparable to the dipole that naturally depends on the smoothing scales. In the end, we discussed this result having an eye on the look-elsewhere-effect. We believe our results may indicate an anomalous patch in the CMB sky that warrants further investigation.

A New Species of the Genus Tropidophorus Duméril, Bibron, 1839 (Reptilia: Squamata: Scincidae) from China-Vietnam Border Region in Southeastern Yunnan Province, China

Based on morphological and genetic data, we describe a new species of Tropidophorus from the tropical karst landscape in southeastern Yunnan Province, China, close to the Vietnam border. Phylogenetically, the new species forms a clade with T. baviensis, T. murphyi, and T. hainanus, with p-distances ranging from 4.7–5.1% for the 16S gene and 3.9–6.8% for 12S gene. Morphologically, the new species shares the karst morphotype of Tropidophorus, particularly similar as T. murphyi and T. baviensis, in which all having a dorsally compressed head and body, smooth dorsal head scales, and distinctively keeled body scales. However, the new species can be distinguished from these similar species by numbers of supralabial scales, ventral scales, scales around the tail at the10th subcaudal, and a larger body size. We emphasize the urgency of conservation for the tropical karst landscape in northern Indochina.

Pitiriasis Versikolor

Pityriasis versicolor is an infectious disease that arises due to decreased immunity and is chronic. This disease is caused by the fungus Malassezia sp. which is characterized by hypopigmented or hyperpigmented macules, which can even be accompanied by erythematous and smooth scales. Infection occurs more often in areas with relatively higher temperatures and humidity. Pityriasis versicolor has a worldwide prevalence of up to 50% in tropical countries and 1.1% in cold climates. The incidence of pityriasis versicolor is the same in all races, but is more frequently seen in dark-skinned individuals due to changes in skin pigmentation. This case report describes a 10 year old girl who came with complaints of white spots appearing on her face for 8 months. The initial appearance of the spots is accompanied by itching when sweating. Dermatological examination revealed multiple hypopigmented macules of lenticular to nummular size with well-defined borders with fine scales. On examination with 20% KOH, grouped spores and short hyphae appear like spaghetti and meatballs. Clustered spores are a sign of colonization, while hyphae indicate infection. Pityriasis versicolor therapy consists of administering antifungals which can be done topically and systemically. Furthermore, patients are educated to always keep their skin dry, reduce activities that cause excessive sweating, and wear clothing that is not tight and absorbs sweat.

Weighted compact nonlinear scheme based on smooth scale separation for self-adaptive turbulence eddy simulations

Multiscale compressible turbulent flow is widely present in the aerospace field, and the co-existence of shock wave discontinuities and multi-scale turbulence in the flow field poses significant challenges for high-fidelity numerical simulation. To design high-order nonlinear scheme to improve the accuracy of complex turbulence simulation with stable shock wave capture, a weighted compact nonlinear scheme – targeted essentially non-oscillatory (WCNS-T) scheme is developed based on targeted essentially non-oscillatory scheme within the WCNS framework. Also, an improved variant of WCNS-T with smooth scale separation (denoted as WCNS-ST) is proposed from the perspective of both numerical convergence and accuracy. The numerical properties of different nonlinear weights are discussed in classical numerical problems, including spectral properties analysis, and two-dimensional Riemann problem. Then, the newly developed WCNS-ST scheme based on smooth scale separation was used to combine a unified turbulence model called Self-Adaptive Turbulence Eddy Simulation (SATES), which is applied to simulate subsonic flow past a 30P30N airfoil and supersonic base flow. The good convergence and numerical results are obtained using the newly developed WCNS-ST scheme, whereas WCNS-T shows worse convergence. In addition, adaptive dissipation control is further introduced for the WCNS-ST scheme, and the new variant (denoted as WCNS-STA) still shows good residual convergence and predicts more accurate results due to low numerical dissipation. The above results indicate that the proposed smooth scale separation and its WCNS-STA scheme have a good performance in SATES simulations of multiscale flow problems, making it more potential for complex engineering applications.

Comparing Mass Mapping Reconstruction Methods with Minkowski Functionals

Using higher-order statistics to capture cosmological information from weak lensing surveys often requires a transformation of observed shear to a measurement of the convergence signal. This inverse problem is complicated by noise and boundary effects, and various reconstruction methods have been developed to implement the process. Here we evaluate the retention of signal information of four such methods: Kaiser-Squires, Wiener filter, 𝙳𝚊𝚛𝚔𝙼𝚊𝚙𝚙𝚢, and 𝙳𝚎𝚎𝚙𝙼𝚊𝚜𝚜. We use the higher order statistics 𝑀𝑖𝑛𝑘𝑜𝑤𝑠𝑘𝑖 𝑓𝑢𝑛𝑐𝑡𝑖𝑜𝑛𝑎𝑙𝑠 to determine which method best reconstructs the original convergence with efficiency and precision. We find 𝙳𝚎𝚎𝚙𝙼𝚊𝚜𝚜 produces the tightest constraints on cosmological parameters, while Kaiser-Squires, Wiener filter, and 𝙳𝚊𝚛𝚔𝙼𝚊𝚙𝚙𝚢 are similar at a smoothing scale of 3.5 arcmin. We also study the MF inaccuracy caused by inappropriate training sets in the 𝙳𝚎𝚎𝚙𝙼𝚊𝚜𝚜 method and find it to be large compared to the errors, underlining the importance of selecting appropriate training cosmologies.

Film Cooling Performances Under Various Upstream Roughness Conditions: Experimental Investigations and Similarity Hypothesis

Abstract Roughness caused by deposition, erosion, and additive manufacturing can significantly affect gas turbine efficiency. Previous research has often examined film cooling performance under limited roughness configurations, resulting in inconclusive findings. In this study, film cooling performances under various upstream roughness conditions were investigated to simulate the roughness-affected film cooling performance of the suction side and the endwall. Three roughness heights (k/D = 0.1, 0.2, and 0.4) and shapes (ks/k = 0.17, 0.67, and 1.95) were selected to cover a wide range of surface roughness characteristics. Three blowing ratios were examined (M = 0.5, 1.0, and 1.5). The weakly roughened surfaces showed improved cooling effectiveness as k/D increased. Meanwhile, the moderately and severely roughened surfaces showed a decrease in cooling effectiveness with increasing k/D at M = 0.5 and 1.0 but an increase at M = 1.5. Cases with shallower and higher roughness elements at M = 1.5 outperformed the smooth plate. Subsequently, a similarity hypothesis for film cooling effectiveness was proposed. At all blowing ratios, the scaled cooling effectiveness profiles converged around the smooth plate results for ks/D < 0.391, encompassing common turbine roughness scales, including irregularly roughened surfaces. Deviations emerged at ks/D = 0.782, and they were correlated with the deteriorated regions observed at various blowing ratios. Ensemble-averaged scaled cooling effectiveness exponentially grew with increasing roughness scale for all blowing ratios, and empirical expressions based on smooth plate result and roughness scale were proposed.

Towards Cosmography of the Local Universe

Anisotropies in the distance-redshift relation of cosmological sources are expected due to large-scale inhomogeneities in the local Universe. When the observed sources are tracing a large-scale matter flow in a general spacetime geometry, the distance-redshift relation with its anisotropies can be described with a geometrical prediction that generalises the well-known Friedmann-Lemaître-Robertson-Walker result. Furthermore, it turns out that a finite set of multipole coefficients contain the full information about a finite-order truncation of the distance-redshift relation of a given observer. The multipoles of the distance-redshift relation are interesting new cosmological observables that have a direct physical interpretation in terms of kinematical quantities of the underlying matter flow. Using light cones extracted from N-body simulations we quantify the anisotropies expected in a Λ cold dark matter cosmology by running a Markov chain Monte Carlo analysis on the observed data. In this observational approach the survey selection implements an implicit smoothing scale over which the effective rest frame of matter is fitted. The perceived anisotropy therefore depends significantly on the redshift range and distribution of sources. We find that the multipoles of the expansion rate, as well as the observer’s velocity with respect to the large-scale matter flow, can be determined robustly with our approach.

A theoretical view of the T-web statistical description of the cosmic web

Context. The objective classification of the cosmic web into different environments is an important aspect of large-scale structure studies, as it can be used as a tool to study the formation of structures (halos and galaxies) in mode detail, and it forms a link between their properties and the large-scale environment; these different environments also offer another class of objects whose statistics contain cosmological information. Aims. In this paper, we present an analytical framework to compute the probability of the different environments in the cosmic web based on the so-called T-web formalism, which classifies structures into four different classes (voids, walls, filaments, and knots) based on the eigenvalues of the Hessian of the gravitational potential, often called the tidal tensor. Methods. Our classification method relies on studying whether the eigenvalues of this Hessian matrix are above or below a given threshold and thus requires knowledge of the joint probability distribution of those eigenvalues. We performed a change of variables in terms of rotational invariants, which are polynomials of the field variables and minimally correlated. We studied the distribution of those variables in the linear and quasi-linear regimes with the help of a so-called Gram-Charlier expansion, using tree-order Eulerian perturbation theory to compute the Gram-Charlier coefficients. This expansion then allowed us to predict the probability of the four different environments as a function of the chosen threshold and at a given smoothing scale and redshift for the density field. We checked the validity regime of our predictions by comparing those predictions to measurements made in the N-body Quijote simulations. Results. Working with fields normalised by their linear variance, we find that scaling the threshold value with the non-linear amplitude of fluctuations allows us to capture almost the entire redshift evolution of the probabilities of the four environments, even if we assume that the density field is Gaussian (corresponding to the linear regime of structure formation). We also show that adding mild non-Gaussian corrections with the help of a Gram-Charlier expansion – hence introducing corrections that depend on third-order cumulants of the field – provides even greater accuracy, allowing us to obtain very precise predictions for cosmic web abundances up to scales of as small as ∼5 Mpc h−1 and redshifts down to z ∼ 0.

Luminous giants populate the dense Cosmic Web

Context. Giant radio galaxies (GRGs, giant RGs, or giants) are megaparsec-scale, jet-driven outflows from accretion disks of supermassive black holes, and represent the most extreme pathway by which galaxies can impact the Cosmic Web around them. A long-standing but unresolved question is why giants are so much larger than other radio galaxies. Aims. It has been proposed that, in addition to having higher jet powers than most RGs, giants might live in especially low-density Cosmic Web environments. In this work, we aim to test this hypothesis by pinpointing Local Universe giants and other RGs in physically principled, Bayesian large-scale structure reconstructions. Methods. More specifically, we localised a LOFAR Two-metre Sky Survey (LoTSS) DR2–dominated sample of luminous (lν(ν = 150 MHz)≥1024 W Hz−1) giants and a control sample of LoTSS DR1 RGs, both with spectroscopic redshifts up to zmax = 0.16, in the BORG SDSS Cosmic Web reconstructions. We measured the Cosmic Web density on a smoothing scale of ∼2.9 Mpc h−1 for each RG; for the control sample, we then quantified the relation between RG radio luminosity and Cosmic Web density. With the BORG SDSS tidal tensor, we also measured for each RG whether the gravitational dynamics of its Cosmic Web environment resemble those of clusters, filaments, sheets, or voids. Results. For both luminous giants and general RGs, the Cosmic Web density distribution is gamma distribution–like. Luminous giants populate large-scale environments that tend to be denser than those of general RGs. This result is corroborated by gravitational dynamics classification and a cluster catalogue crossmatching analysis. We find that the Cosmic Web density around RGs with 150 MHz radio luminosity lν is distributed as 1 + ΔRG | Lν = lν ∼ Γ(k, θ), where k = 4.8 + 0.2 · √, θ = 1.4 + 0.02 · √, and √:= log10(lν (1023 W Hz−1)−1). Conclusions. This work presents more than a thousand inferred megaparsec-scale densities around radio galaxies, which may be correct up to a factor of order unity – except in clusters of galaxies, where the densities can be more than an order of magnitude too low. We pave the way to a future in which megaparsec-scale densities around RGs are common inferred quantities, which help to better understand their dynamics, morphology, and interaction with the enveloping Cosmic Web. Our data demonstrate that luminous giants inhabit denser environments than general RGs. This shows that – at least at high jet powers – low-density environments are no prerequisite for giant growth. Using general RGs, we quantified the relation between radio luminosity at 150 MHz and Cosmic Web density on a smoothing scale of ∼2.9 Mpc h−1. This positive relation, combined with the discrepancy in radio luminosity between known giants and general RGs, reproduces the discrepancy in Cosmic Web density between known giants and general RGs. Our findings are consistent with the view that giants are regular, rather than mechanistically special, members of the radio galaxy population.

A new high-order shock-capturing TENO scheme combined with skew-symmetric-splitting method for compressible gas dynamics and turbulence simulation

The high-order shock-capturing scheme is one of the main building blocks for the simulation of the compressible fluid characterized by strong shockwaves and broadband length scales. However, the classical shock-capturing scheme fails to perform long-time stable and non-dissipative simulations since the quadratic invariants associated with the conservation equations cannot be conserved as a result of the inherent numerical dissipation. Additionally, the overall computational cost for classical shock-capturing schemes is quite expensive as a result of the time-consuming local characteristic decomposition and the nonlinear-weights computing process. In this work, based on a new efficient discontinuity indicator, which distinguishes the non-smooth high-wavenumber fluctuations and discontinuities from smooth scales in the wavenumber space, a paradigm of high-order shock-capturing scheme by recasting the non-dissipative skew-symmetric-splitting method with newly optimized dispersion property for smooth flow scales and invoking the nonlinear targeted ENO (TENO) schemes for non-smooth discontinuities is proposed. The resulting TENO-S scheme not only successfully performs long-time stable computations for smooth flows without numerical dissipation, but also recovers the robust shock-capturing capabilities with adaptive numerical dissipation. Without the necessity of parameter tuning case by case, extensive benchmark simulations involving a wide range of flow length scales and strong discontinuities demonstrate that the proposed TENO-S scheme performs significantly better than the straightforward deployment of WENO/TENO-family schemes with better spectral property and higher computational efficiency.

Bayesian Linear Inverse Problems in Regularity Scales with Discrete Observations

AbstractWe obtain rates of contraction of posterior distributions in inverse problems with discrete observations. In a general setting of smoothness scales we derive abstract results for general priors, with contraction rates determined by discrete Galerkin approximation. The rate depends on the amount of prior concentration near the true function and the prior mass of functions with inferior Galerkin approximation. We apply the general result to non-conjugate series priors, showing that these priors give near optimal and adaptive recovery in some generality, Gaussian priors, and mixtures of Gaussian priors, where the latter are also shown to be near optimal and adaptive.

Use of the dilated electron propagator in conjunction with the modified smooth exterior scaling method to characterize 2S Be+ (1s−1), 2S Ne+ (1s−1) Auger and 2P Be− shape resonances

The modified smooth exterior scaling (MSES) method is an efficient method to impose outgoing boundary conditions in electron–atom or electron–molecule scatterings.

High-Temperature Oxidation Behavior of FeCoCrNi+(Cu/Al)-Based High-Entropy Alloys in Humid Air

Previous studies showed some transition metal high-entropy alloy (HEA) compositions can have good oxidation resistance in air up to 800 °C. Four equiatomic HEAs have been developed based on FeCoCrNi with additions of Mn, Cu, Al or Al+Cu. The oxidation behavior of these HEAs was compared in humid (10 vol.% H2O) air at 800 °C for 100–500 h to investigate the influence of water vapor on the oxidation mechanisms. The Cu- and Al-containing alloys exhibited improved oxidation resistance over the Mn composition. For the Cu-containing alloy, a local attack of the Cu-rich phase was observed, which formed an Fe/Ni/Co/Cr spinel that was surrounded by Cr2O3. This oxide was thicker for the humid air atmosphere when compared to dry air, and the transition of the Cu oxide to the spinel was accelerated. The Al-containing HEA formed a thin Al2O3 scale with humidity suppressing AlN formation and forming a smoother oxide layer. The Al+Cu composition had the highest overall oxidation resistance (minimal local attack, no nitridation) and also showed a smooth oxide scale topography under humid air oxidation as opposed to a plate-like, rougher scale under dry air.

An elastic framework construction method based on task migration in edge computing

AbstractEdge computing (EC) serves as an effective technology, empowering end‐users to attain high bandwidth and low latency by offloading tasks with high computational demands from mobile devices to edge servers. However, a major challenge arises when the processing load fluctuates continuously, leading to a performance bottleneck due to the inability to rescale edge node (EN) resources. To address this problem, the approach of task migration is introduced, and EN load prediction model, the resource constrained model, optimal communication overhead model, optimal task migration model, and energy consumption model are built to form a theoretical foundation from which to propose a task migration based resilient framework construction method in EC. With the aid of the domino effect and the combined effect of task migration, a dynamic node‐growing algorithm (DNGA) and a dynamic node‐shrinking algorithm (DNSA), both based on the task migration strategy, are proposed. Specifically, the DNGA smoothly expands the EN scale when the processing load increases, while the DNSA shrinks the EN scale when the processing load decreases. The experimental results show that for standard benchmarks deployed on an elastic framework, the proposed method realizes a smooth scaling mechanism in the EC, which reduces the latency and improves the reliability of data processing.

Exiting Inflation with a Smooth Scale Factor

The expectation that the physical expansion of space occurs smoothly may be expressed mathematically as a requirement for continuity in the time derivative of the metric scale factor of the Friedmann–Robertson–Walker cosmology. We explore the consequences of imposing such a smoothness requirement, examining the forms of possible interpolating functions between the end of inflation and subsequent radiation- or matter-dominated eras, using a straightforward geometric model of the interpolating behavior. We quantify the magnitude of the cusp found in a direct transition from the end of slow-roll inflation to the subsequent era, analyze the validity of several smooth interpolator candidates, and investigate equation-of-state and thermodynamic constraints. We find an order-of-magnitude increase in the size of the universe at the end of the transition to a single-component radiation or matter era. We also evaluate the interpolating functions in terms of the standard theory of preheating and determine the effect on the number of bosons produced.

A new type of non-polynomial based TENO scheme for hyperbolic conservation laws

For classical WENO/TENO reconstructions, the high-order polynomial interpolation is one of the main building-blocks for constructing the numerical fluxes. However, due to the inherent characteristics of polynomials, the polynomial interpolation is not suitable to represent the flow scale with sharp transitions such as high-wavenumber fluctuations or discontinuities. In this work, based on a new candidate stencil arrangement with explicit detection of non-smooth regions, a new shock-capturing framework is proposed by combining the infinitely differentiable non-polynomial RBF-based reconstruction in smooth regions with the jump-like non-polynomial interpolation for genuine discontinuities. The resulting scheme not only achieves the desired high-order accuracy for smooth flow scales but also resolves the genuine discontinuities with a sub-cell resolution. Moreover, with the observation that the built-in parameter has a significant impact on the basic shape of the Gaussian RBF kernel function, a nonlinear adaptation strategy for the shape parameter is proposed to incorporate the local features of the flow field and further minimize the numerical dissipation errors for smooth flow scales. In order to demonstrate the robust shock-capturing and high wave-resolution properties of the proposed non-polynomial based scheme, a set of challenging benchmark cases with a wide range of Mach numbers is simulated without the necessity of parameter tuning case by case.

From home energy management systems to communities energy managers: The use of an intelligent aggregator in a community in Algarve, Portugal

This paper describes the development of community energy management systems (CEMS). A CEMS allows optimal energy sharing within energy communities, as it is a central system that makes the global management of the entire community. The proposed CEMS is based on mixed-integer linear programming (MILP), operating under the receding horizon concept of Model Predictive Control (MPC). A systematic classification of electric appliances, the use of external information such as weather information and energy prices, as well as the use of intelligent forecasting techniques enables the proposed approach to achieve an excellent efficiency. It also allows for an easy installation of as well as a smooth scaling with an increasing number of houses. The system is tested in a real community in Algarve, Portugal. Different simulations are compared to experimental operation and include cases with and without sharing of energy, different resources allocated to the houses considered, and the use of different tariffs. CEMS formulations include sharing of energy without restriction, as well as employing different allocation coefficients strategies. The results show that for the community under study when managed by CEMS such as the one presented in this paper, it would result in significant cost reductions when compared to the case where there is no energy community.