Miracle-dz/UniFAR-FTUs huggingface dataset:
The effects of changing resolution on mesocale modelling of line convection and slantwise circulations in FASTEX IOP16

Data are presented from modelling a rapidly developing cyclone, in intensive observation period 16 of the Fronts and Atlantic Storm Tracks Experiment, using the new non‐hydrostatic version of the Met Office Unified Model at a number of different horizontal and vertical resolutions. The model produces a good representation of the system, including multiple fronts with line convection, cloud heads and slantwise cross‐frontal circulations similar to those seen in the observations. Results from the model with various grid lengths, from 60 km nested down to 2 km with 45 vertical levels, show that more realistic detail is produced as the grid length is reduced but that the large‐scale structures remain consistent. By spectral analysis it is found that structures on scales shorter than approximately five grid lengths are attenuated. The line convection at the fronts is aliased onto the grid‐length scale except in the 2 km model where evidence of a three‐dimensional structure starts to appear. The 2 and 4 km models have also been run with enhanced vertical resolutions. It is concluded that whilst a 24 km 45‐level model is sufficient to represent the overall frontal structure, a model with resolution at least 2 km in the horizontal and 90 vertical levels is required to represent small‐scale multiple slantwise circulations similar to those observed in the dropsonde data. © Crown copyright 2003.
Testing the local spacetime dynamics by heliospheric radiocommunication methods

According to general relativistic theories, cosmological spacetime is dynamic. This prediction is in excellent agreement with the huge majority of astronomical observations on large cosmic scales, especially the observations of cosmological redshifts of distant galaxies. However, on scales of heliospheric distances, verifications of general relativistic effects are based on Schwarzschild metric tests or kinetical corrections, such as the perihelion motion of Mercury, photon deflection at the Sun and gravitational photon redshifts in central gravity fields. As we will show in this paper, there is, however, a chance to detect new cosmologically relevant features on heliospheric scales by careful study of photon propagations in the local spacetime metrics, based on red- or blueshifts as a clear, but up to now overlooked, signature of the local spacetime dynamics. Thus, we propose the challenging possibility of carrying out experiments of cosmological relevance by simply using high-precision radio tracking of heliospheric spaceprobes, as already practised in cases like Pioneer-10/11, Galileo and Ulysses.
On modelling and diagnostic checking of vector periodic autoregressive time series models

Abstract. Vector periodic autoregressive time series models (PVAR) form an important class of time series for modelling data derived from climatology, hydrology, economics and electrical engineering, among others. In this article, we derive the asymptotic distributions of the least squares estimators of the model parameters in PVAR models, allowing the parameters in a given season to satisfy linear constraints. Residual autocorrelations from classical vector autoregressive and moving‐average models have been found useful for checking the adequacy of a particular model. In view of this, we obtain the asymptotic distribution of the residual autocovariance matrices in the class of PVAR models, and the asymptotic distribution of the residual autocorrelation matrices is given as a corollary. Portmanteau test statistics designed for diagnosing the adequacy of PVAR models are introduced and we study their asymptotic distributions. The proposed test statistics are illustrated in a small simulation study, and an application with bivariate quarterly West German data is presented.
High-resolution near-infrared and millimeter-wave spectroscopy of NGC 7027

The compact planetary nebula NGC 7027 has been observed at high spectral resolution at near-infrared and millimeter wavelengths. In the near-infrared, the line profiles of H Brackett . gamma. , He ii 10--4, He i 2/sup 1/P--2/sup 1/S are presented and discussed. The widths and intensities of the three lines are generally in agreement with visual and radio recombination line observations. New J = 1. -->. 0 /sup 12/CO and /sup 13/CO millimeter-wave observations are also presented. While /sup 12/CO was readily detected, /sup 13/CO emission at a level reported previously for NGC 7027 could not be confirmed. A peak antena temperature of T(/sub A/ = 0.035 +- 0.007 K was found for /sup 13/CO. An isotope ratio of (/sup 12/C)/(/sup 13/C)> or =36 +- 6 is derived for the planetary. On the basis of this value, it is suggested that NGC 7027 evolved from a 3 M/sub sun/ star that passed through at least the asymptotic giant branch stage.
A numerical analysis of a class of generalized Boussinesq‐type equations using continuous/discontinuous FEM

An improved class of Boussinesq systems of an arbitrary order using a wave surface elevation and velocity potential formulation is derived. Dissipative effects and wave generation due to a time‐dependent varying seabed are included. Thus, high‐order source functions are considered. For the reduction of the system order and maintenance of some dispersive characteristics of the higher‐order models, an extra O(μ2n+2) term (n ∈ ℕ) is included in the velocity potential expansion. We introduce a nonlocal continuous/discontinuous Galerkin FEM with inner penalty terms to calculate the numerical solutions of the improved fourth‐order models. The discretization of the spatial variables is made using continuous P2 Lagrange elements. A predictor‐corrector scheme with an initialization given by an explicit Runge–Kutta method is also used for the time‐variable integration. Moreover, a CFL‐type condition is deduced for the linear problem with a constant bathymetry. To demonstrate the applicability of the model, we considered several test cases. Improved stability is achieved. Copyright © 2011 John Wiley & Sons, Ltd.
Mathematics of Sudoku I

In an earlier article [1] of Bertram Felgenhauer and the second author, the number of different Sudoku grids was computed to be N0 = 6670903752021072936960 ≈ 6.671 × 10 . However, distinct solutions were treated as different, even when one could be transformed into another by some symmetry. However, you may feel that two grids should not be counted differently if, say, the second is just the first rotated by 90 degrees. Similarly, one can reflect a grid to get another valid grid – should these be counted differently? And one can relabel all the entries (exchanging 1s and 2s, for example) to give another grid. In this note, we want to explain how to refine the counting method of [1] to find how many essentially different grids there are, if we allow various possible symmetries.
The Pressure force induced by neutral, turbulent flow over hills

The pressure force induced by neutral, turbulent flow over small-scale hills is considered. The influence that the level of turbulence closure has on liner, analytical expressions for the force is evaluated. The two-dimensional linear expressions are then extended to three dimensions and a heuristic extension to moderate and steep slopes, for which nonlinear effects are important, is proposed. The predictions of these various expressions are compared with results from a three-dimensional numerical model employing a 1 1/2-order turbulence-closure model, and very good agreement is found. The numerical-model results supports the idea that, sufficiently far above the hills, the areally averaged velocity profile varies approximately logarithmically with height but with an enhanced, or effective, roughness length and a friction velocity equal to the square root of the total surface force per unit area and unit density. Using the theoretical results for the pressure force, discussed above, and approximate expression for the effective roughness length is obtained that agrees well with values from the model, and also matches with existing expressions that are valid for two-dimensional hills with either very low or very large slopes. Qualitative agreement is also found with the limited number of observed values of roughness length in hilly terrain. These results suggest that the effective roughness length is an accurate and convenient method of parametrizing the drag due to subgrid-scale orography in large-scale numerical-weather-prediction and climate models.
Charge-density waves and superlattices in the metallic layered transition metal dichalcogenides

The d1 layer metals TaS 2 , TaSe 2 , NbSe 2 , in all their various polytypic modifications, acquire, below some appropriate temperature, phase conditions that their electromagnetic properties have previously revealed as 'anomalous'. Our present electron-microscopic studies indicate that this anomalous behaviour usually included the adoption, at some stage, of a superlattice. The size of superlattice adopted often is forecast in the pattern of satellite spotting and strong diffuse scattering found above the transition. Our conclusions are that charge-density waves and their concomitant periodic structural distortions occur in all these 4d 1 /5d 1 dichalcogenides. We have related the observed periodicities of these CDW states to the theoretical form of the parent Fermi surfaces. Particularly for the 1T octahedrally coordinated polytypes the Fermi surface is very simple and markedly two-dimensional in character, with large near-parallel walls. Such a situation is known theoretically to favour the formation of charge and spin-density waves. When they first appear, the CDWs in the 1T (and 4Hb) polytypes are incommensurate with the lattice. This condition produes a fair amount of gapping in the density of states at the Fermi level. For the simplest case of 1T-TaSe 2 , the room temperature superlattice is realized when this existing CDW rotates into an orientation for which it then become commensurate. At this first-order transition the Fermi surface energy gapping increases beyond that generated by the incommensurate CDW, as is clearly evident in the electromagnetic properties. For the trigonal prismatically coordinated polytypes, CDW formation is withheld to low temperatures, probably because of the more complex band structures. This CDW state (in the cases measured) would seem at once commensurate, even though the transition is, from a wide variety of experiments, apparently second order. A wide range of doped and intercalated materials have been used to substantiate the presence of CDWs in these compounds, and to clarify the effect that their occurrence has on the physical properties. The observations further demonstrate the distinctiveness of the transition metal dichalcogenide layer compounds, and of the group VA metals in particular.
Stimulated phenomena in the surface Cherenkov process by unmagnetized electron beam

The operability of the surface Cherenkov laser with unmagnetized electron beam is considered. The small-signal gain of the surface Cherenkov laser for various regimes is calculated. The dependence of the gain on the electron beam angular spread is analyzed. The quantum mechanical consideration shows the possibility of the electron-beam quantum modulation after the interaction.
Second Order Efficiency of Minimum Contrast Estimators in a Curved Exponential Family

This paper presents a sufficient condition for second order efficiency of an estimator. The condition is easily checked in the case of minimum contrast estimators. The a*-minimum contrast estimator is defined and proved to be second order efficient for every a, 0 < a < 1. The Fisher scoring method is also considered in the light of second order efficiency. It is shown that a contrast function is associated with the second order tensor and the affine connection. This fact leads us to prove the above assertions in the differential geometric framework due to Amari.
High Performance Preconditioning

The discretization of second-order elliptic partial differential equations over three-dimensional rectangular regions, in general, leads to very large sparse linear systems. Because of their huge order and their sparseness, these systems can only be solved by iterative methods using powerful computers, e.g., vector supercomputers. Most of those methods are only attractive when used in combination with a so-called preconditioning matrix. Unfortunately, the more effective preconditioners, such as successive over-relaxation and incomplete decompositions, do not perform very well on most vector computers if used in a straightforward manner. In this paper it is shown how a rather high performance can be achieved for these preconditioners.
Classification of hyperspectral remote-sensing images based on sparse manifold learning

Abstract Sparsity preserving projections (SPP) has drawn more and more attention recently. However, the SPP only focuses on the sparse structure but ignores the discriminant information of labeled samples. We proposed a new sparse manifold learning method, called sparse discriminant embedding (SDE), for hyperspectral image (HSI) classification. The SDE utilizes the merits of both sparsity property and manifold structure. It not only preserves the sparse reconstructive relations but also explicitly boosts the discriminant manifold structure of the data, and the discriminating power of the SDE is further improved than the SPP. Experiments on the Flightline C1, Washington DC Mall, and Botswana HSI datasets are performed to demonstrate the effectiveness of the proposed SDE method.
Analysis of solvability and applications of stochastic optimal control problems through systems of forward-backward stochastic differential equations.

A stochastic metapopulation model is investigated. The model is motivated by a deterministic model previously presented to model the black bear population of the Great Smoky Mountains in east Tennessee. The new model involves randomness and the associated methods and results differ greatly from the deterministic analogue. A stochastic differential equation is studied and the associated results are stated and proved. Connections between a parabolic partial differential equation and a system of forward-backward stochastic differential equations is analyzed. A “four-step” numerical scheme and a Markovian iterative type numerical scheme are implemented. Algorithms and programs in the programming languages C and R are provided. Convergence speed and accuracy is compared for two numerical methods. Moreover, simulation results are presented and discussed.
Impacts of the ice‐cover and sea‐surface temperature on a polar low over the Nordic seas: a numerical case study

Extreme mesoscale weather in the Arctic region consists mainly of cases with shallow fronts that often form in the vicinity of the ice‐edge and intense storms called polar lows. This article describes high‐resolution numerical simulations of a severe weather event that occurred on 1 March 2008 over the Barents Sea. The event was recorded during the IPY–THORPEX field experiments carried out during February and March 2008. The numerical simulations indicated the formation of a low‐pressure system over the Barents Sea on 29 February 2008 due to baroclinic instability. On 1 March, the surface low moved onto the sea‐ice around Spitsbergen and decayed later on. The conditions that prevailed before the dissipation of the surface low were favourable for the formation of a polar low. Two experiments were performed to test the possibilities of triggering a polar low through certain modifications to the surface conditions. In the first experiment, the sea‐ice around Spitsbergen was removed. No polar low developed in this case, since the static stability was too high. In the second experiment, an attempt to reduce the static stability was made by raising the sea‐surface temperature by 5 K. The surface low persisted over the Barents Sea area due to the increased surface heating and led to a strong outbreak of Arctic air over the Norwegian Sea on 2 March. The Arctic‐air outbreak formed a sharp baroclinic zone which was absent in the control simulation. A secondary mesoscale low was triggered near the baroclinic zone over the Norwegian Sea, which grew into an intense polar low with surface winds reaching hurricane force. Formation of the polar low was due to baroclinic instability, whereas convective instability was important during the growth of the low. Copyright © 2011 Royal Meteorological Society
Non-Gaussian behavior and anticorrelations in ultrathin gate oxides after soft breakdown

The time dependence of the gate voltage VG(t) after soft breakdown of metal-oxide-semiconductor capacitors with a 2.4 nm SiO2 layer has been measured. It is found that the VG(t) fluctuation distributions are non-Gaussian, but can be described by a Levy stable distribution. The long-range correlations in VG(t) are investigated within the detrended fluctuation analysis. The Hurst exponent is found to be H=0.25±0.04 independent of the value of the stress current density J. It is argued that these are universal features of soft breakdown and are due to trapping–detrapping of electrons in and away from the primary percolation path.
Evaluation of a proposed optimization method for discrete-event simulation models

Optimization methods combined with computer-based simulation have been utilized in a wide range of manufacturing applications. However, in terms of current technology, these methods exhibit low performance levels which are only able to manipulate a single decision variable at a time. Thus, the objective of this article is to evaluate a proposed optimization method for discrete-event simulation models based on genetic algorithms which exhibits more efficiency in relation to computational time when compared to software packages on the market. It should be emphasized that the variable's response quality will not be altered; that is, the proposed method will maintain the solutions' effectiveness. Thus, the study draws a comparison between the proposed method and that of a simulation instrument already available on the market and has been examined in academic literature. Conclusions are presented, confirming the proposed optimization method's efficiency.
Experiments on the stability of spiral flow at low axial Reynolds numbers

The hydrodynamic stability of viscous flow between rotating cylinders with superposed axial flow has been studied experimentally. The experiments were confined to the case where the outer cylinder is at rest and the gap between cylinders is small. Particular attention has been given to small rates of axial flow. The results compare satisfactorily with Chandrasekhar’s perturbation theory valid under these conditions.
Modeling and Forecasting the Onset and Duration of Severe Radiation Fog under Frost Conditions

Abstract A case of a severe radiation fog during frost conditions is analyzed as a benchmark for the development of a very high-resolution NWP model. Results by the Weather Research and Forecasting model (WRF) and the High-Resolution Limited-Area Model (HIRLAM) are evaluated against detailed observations to determine the state-of-the-art in fog forecasting and to derive requirements for further research and development. For this particular difficult case, WRF is unable to correctly simulate the fog for any of the parameterizations and model configurations utilized. Contrary, HIRLAM does model the onset of fog, but is unable to represent it beyond the lowest model layer, which leads to an early dispersal of fog in the morning transition. The sensitivity of fog forecasts to model formulation is further analyzed with a high-resolution single-column version of HIRLAM, and with the Duynkerke single-column model as a reference. The single-column results are found to be sensitive to the proper specification of t.
Effect of Electric Charge on Collisions between Cloud Droplets

AbstractA simple model is presented for the calculation of the effect of electric charges on the collision and coalescence of cloud droplets, a topic that is of importance for coalescence-induced natural rainfall and for the possible effectiveness of techniques for increasing rainfall by injection of ions into the atmosphere. Whereas electric charges of opposite sign enhance the collision efficiency of cloud droplets, the effect when all droplets bear charges of the same sign depends strongly upon the droplet sizes and separations and upon the ratio of charges on each of a droplet pair. The conditions under which coalescence is increased exist for only a very small fraction of actual cloud structures.
NEGATIVE PROBABILITIES AT WORK IN THE M/D/1 QUEUE

This article derives amazingly accurate approximations to the state probabilities and waiting-time probabilities in the M/D/1 queue using a two-phase process with negative probabilities to approximate the deterministic service time. The approximations are in the form of explicit expressions involving geometric and exponential terms. The approximations extend to the finite-capacity M/D/1/N + 1 queue.
A novel fitted finite volume method for the Black-Scholes equation governing option pricing

In this paper we present a novel numerical method for a degenerate partial differential equation, called the Black-Scholes equation, governing option pricing. The method is based on a fitted finite volume spatial discretization and an implicit time stepping technique. To derive the error bounds for the spatial discretization of the method, we formulate it as a Petrov-Galerkin finite element method with each basis function of the trial space being determined by a set of two-point boundary value problems defined on element edges. Stability of the discretization is proved and an error bound for the spatial discretization is established. It is also shown that the system matrix of the discretization is an M-matrix so that the discrete maximum principle is satisfied by the discretization. Numerical experiments are performed to demonstrate the effectiveness of the method.
Sm:YAG optical pressure sensor to 180 GPa:Calibration and structural disorder

We report ultrahigh pressure calibration and fluorescence intensity measurements of Sm:YAG to 180 GPa in a diamond anvil cell at room temperature. Several fluorescence emission bands excited by argon ion laser were followed with increasing pressure and it was observed that Y4 band was the most intense in the pressure regime of 100–180 GPa. The Y4 band is calibrated against the R band of ruby to 180 GPa. Irreversible changes in the line intensities above 100 GPa were observed in Sm:YAG and quenched to ambient pressure. Linewidths of the fluorescence bands of the quenched phase indicate structural disorder. In contrast to ruby pressure sensor, the Y4 emission band of Sm:YAG is easily detectable at ultrahigh pressures.
Quantitative study of attractor neural networks retrieving at low spike rates: II. Low-rate retrieval in symmetric networks

A network of current-rate dynamics with a symmetric synaptic matrix is analysed and simulated for its low-rate attractor structure. The dynamics is deterministic, with the noise included in a realistic current-rate transduction function (discussed in part I)The analysis is carried out in mean-field theory. It is shown that at low loading the network retrieves without errors, with uniform low rates, that there are no simple spurious states and that the low-rate attractors, retrieving single patterns, are stable to the admixture of additional patterns. The analysis of the attractors in a network with an extensive number of patterns is carried out in the replica symmetric approximations. The results for the dependence of the retrieval rates on loading level; for the distribution of rates among neurons, as well as for the storage capacity are compared with simulations. Simulations also show that retriewal performance is very robust to random elimination of synapses. Moreover, errors in the stimulus, relative .