Miracle-dz/UniFAR-FTUs huggingface dataset:
Local likelihood tracking of fault lines and boundaries

We suggest locally parametric methods for estimating curves, such as boundaries of density supports or fault lines in response surfaces, in a variety of spatial problems. The methods are based on spatial approximations to the local likelihood that the curve passes through a given point in the plane, as a function of that point. The local likelihood might be a regular likelihood computed locally, with kernel weights (e.g. in the case of support boundary estimation) or a local version of a likelihood ratio statistic (e.g. in fault line estimation). In either case, the local likelihood surface represents a function which is relatively large near the target curve, and relatively small elsewhere. Therefore, the curve may be estimated as a ridge line of the surface; we require only a numerical algorithm for tracking the projection of a ridge into the plane. This approach offers several potential advantages over alternative methods. First, the local (log‐)likelihood surface can be graphed, and the degree of ‘ridginess’ assessed visually, to determine how the level of local smoothing should be varied in different spatial locations in order to emphasize the ridge and hence the curve adequately. Secondly, the local likelihood surface does not need to be computed in anything like its entirety; once we have a reasonable approximation to a point on the curve we may track it by numerically ‘walking along’ the ridge line. Thirdly, the method is appropriate without change for many different types of spatial explanatory variables—gridded, stochastic or otherwise. Three examples are explored in detail; fault lines in response surfaces and in intensity or density surfaces, and boundaries of supports of probability densities.
From interstellar dust to comets: the extended CO source in comet Halley

SomesimplemoleculesincometcomaelikeCO,C2, C3, CN, H2CO appear to be distributed in such a way that they areneitherdirectlyemittedfromthenucleussurfacenorcreated as daughter molecules from more complex gas phase species. The only remaining possible source is the organic component in comet dust. The requirements imposed on the comet dust grains by the distributed CO emission are that they be heated sufciently to evaporate a large fraction of the more volatile fraction of the complex organic refractory molecules and that a largefractionofthesecontainCOgroups.Inferringthedust/gas ratio within the mass limits from the comet dust size (mass) dis- tributionobtainedbytheGiottospacecraftforcometHalley,and assuming that the refractory organics remaining on the silicate cores are the heating agent by solar radiation in fluffy aggre- gates of interstellar core-mantle particles, the upper limits of the total amount of CO provided by dust can be approximately determined as a function of porosity. The resulting maximum CO production rate predicted by the comet dust model is sig- nicantly less than the observed distributed CO abundance. A possiblesolutionliesinthefactthatthedusttogasratiohasbeen underestimated in the dust size distribution employed here, by neglecting efcient dust fragmentation and sublimation in the innermostcoma.Ontheotherhand,itmaynotbeimpossiblethat theextendedCOabundancewasoverestimatedduetothecross- ing of dust jets, the time variation of the comet nucleus activity, and the anisotropic outgassing nature of the nucleus. At this point we can certainly say that, in order to obtain the observed distributed CO production rate from comet dust, it requires not only the organic refractory mantles and very high porosity, but also it seems that more heatable dust must be available than has been deduced from the space observation.
Controlling chaotic systems with disturbance using backstepping design and nonlinear damping

In this paper the attention is focused on the control of chaotic systems in the presence of unknown and bounded disturbance added to the control input. The issue is tackled by exploiting backstepping design and nonlinear damping. In particular, backstepping is proposed as a systematic Lyapunov-based tool for controlling a large class of chaotic systems, whereas nonlinear damping is suggested to counteract the disturbance affecting the control input. Finally, the effectiveness of the proposed approach is illustrated by stabilizing the chaotic dynamics of the Lorenz system in the presence of a disturbance matched with the control input.
Fabrication of polarization-maintaining and absorption-reducing fibers

Low-loss single-polarization fibers with stress-induced birefringence have been fabricated using VAD single-mode fiber preforms. Design criteria have also been clarified with due regard to optimum fiber structure that reduces transmission loss and increases birefringence. As a result of these criteria, the minimum loss of 0.4 dB/km at 1.54 μm, and the birefringence B s of 1.2 \times 10^{-4} at 1.15 μm was obtained. It has been shown that a large refractive-index difference between the core and the cladding Δ, as well as large birefringence, are very effective to stabilize the state of polarization. In a 5-km-long fiber with \Delta = 0.8 percent and B_{s}= 1.2 \times 10^{-4} , crosstalk lower than -20 dB has been obtained.
CONVENIENT MULTIPLE DIRECTIONS OF STRATIFICATION

This paper investigates the use of multiple directions of stratification as a variance reduction technique for Monte Carlo simulations of path-dependent options driven by Gaussian vectors. The precision of the method depends on the choice of the directions of stratification and the allocation rule within each strata. Several choices have been proposed but, even if they provide variance reduction, their implementation is computationally intensive and not applicable to realistic payoffs, in particular not to Asian options with barrier. Moreover, all these previously published methods employ orthogonal directions for multiple stratification. In this work we investigate the use of algorithms producing convenient directions, generally non-orthogonal, combining a lower computational cost with a comparable variance reduction. In addition, we study the accuracy of optimal allocation in terms of variance reduction compared to the Latin Hypercube Sampling. We consider the directions obtained by the Linear Transformation and the Principal Component Analysis. We introduce a new procedure based on the Linear Approximation of the explained variance of the payoff using the law of total variance. In addition, we exhibit a novel algorithm that permits to correctly generate normal vectors stratified along non-orthogonal directions. Finally, we illustrate the efficiency of these algorithms in the computation of the price of different path-dependent options with and without barriers in the Black-Scholes and in the Cox-Ingersoll-Ross markets.
High-frequency nonlinear vibrational control

This paper discusses the feasibility of high-frequency nonlinear vibrational control. Such control has the advantage that it does not require state measurement and processing capabilities that are required in conventional feedback control. Bellman et al. (1986) investigated nonlinear systems controlled by linear vibrational controllers and proved that vibrational control is not feasible if the Jacobian matrix has a positive trace. This paper extends previous work to include nonlinear vibrational controllers. A stability criteria is derived for nonlinear systems with nonlinear controllers, and it is shown that a nonlinear vibrational controller can stabilize a system even if the Jacobian matrix has a positive trace.
Mott–Schottky analysis of flower‐like ZnO microstructures with constant phase element behavior

ZnO was prepared using room temperature bipolar electrochemical process in deionized water. Electron microscopy, powder X‐ray diffraction, and micro‐Raman spectroscopy showed crystallization of the material into the wurtzite hexagonal structure of ZnO, self‐organized in micro‐sized flower‐like shapes that are formed out of individual nanorods preferentially grown along the <0001> direction. The intrinsic electronic properties were evaluated by potentiodynamic electrochemical impedance spectroscopy using Mott–Schottky analysis of semiconductor/liquid junctions. Because the flat band and carrier density are frequency‐dependent, we used an approximation based on fractional order capacitance fitting, and subsequently three different ways to calculate the frequency‐independent effective capacitance of the system. The capacitance computed using the four parameters of single‐dispersion Randle's model, i.e., pseudocapacitance, dispersion coefficient, and series and parallel resistances, is more recommended for the characterization of the electrochemical system.
LEARNING RULE FOR PATTERN RECOGNITION IN HOPFIELD NEURONAL NETWORK

The Hopfield model of associative memories is reconsidered in terms of pattern recognition in presence of noise. A learning rule for the investigated model is deduced. With the obtained learning rule the storing capacity of Hopfield neuronal network is increased from α≃0.14 to the optimal value α=1. The pattern recognition capabilities of the model increase exponentially with the dimensionality of the patterns.
Second‐order spectral local isotropy of the humidity and temperature fields in an urban area

A theoretical and experimental analysis of the humidity and temperature spatial differentials (δ/δxj,) in an urban area is presented. The local isotropy form of the spectra of the streamwise and vertical differentials of a scalar field is derived. The experimental results for the humidity and temperature fields in the lowest part of the urban boundary layer are in satisfactory agreement (at least in form under stable conditions) with the local isotropy model indicating that these fields can be locally isotropic. A strong anisotropy was observed at small wavenumbers of the vertical differentials spectra and it is probably connected with surface-layer plumes. The analysis of the humidity and temperature differentials is extended to their co-spectra and the spectra of the vertical differentials are compared to the streamwise ones. The comparison of the structure parameters of the temperature or the humidity field in the streamwise and the vertical direction, estimated using a spectral and a variance (structure function) method, showed no systematic departure from the isotropic prediction of equality.
On the dynamics of point vortices in an annular region

This paper reviews the results of stability analysis for polygonal configurations of a point vortex system in an annular region depending on the ratio of the inner and outer radii of the annulus. Conditions are found for linear stability of Thomsonʼs configurations for the case N < 7 ? > . The paper also shows that a system of two vortices between parallel walls is a limiting case of a two-vortex system in an annular region, as the radii of the annulus tend to infinity.
Factor Analysis of Ordinal Variables with Full Information Maximum Likelihood

The basic idea of factor analysis is the following. For a given set of manifest variables x1, . , xp one wants to find a set of latent variables ξ1, . , ξk, fewer in number than the manifest variables, that contain essentially the same information. The latent variables are supposed to account for the dependencies among the manifest variables in the sense that if the latent variables are held fixed, the manifest variables would be independent. Classical factor analysis assumes that both the manifest and the latent variables are continuous variables and is usually carried out by factor analyzing the sample covariance or correlation matrix of the manifest variables. There is a long history of methods for fitting factor models to a correlation or covariance matrix, see e.g., Joreskog (2006)
Information Management as a Nexus to Promote the use of Indigenous Medicine and Enhance Public Healthcare Delivery: A Bibliometric Analysis

This paper uses a bibliometric analysis to explore the citations trend in ethnomedicine and information management. A text mining algorithm of a total number of 8, 333 publications (n = 8,333) was conducted based on the title, abstract and keywords to find co-occurrence of key terms in indigenous medicine and information management. The first objective was to analyze the authorship, outputs and citation trends and establish if researchers have been able to establish a nexus between indigenous herbal use and the role of information management in promoting such use. Secondly, the study sought to establish if there is already a link in information management research through collaboration as a nexus to promote indigenous use of herbal medicine and enhance public healthcare delivery systems on the African continent. A computation synthesis of the data was performed using R programming statistical analysis and bibliometric software to visualize the analyzed data. Based on the R programming output, the total author sample size was 35,970 (n = 35,970), and their total publications output was n= 8,333, while the total outputs parameters was as follows: Min = 5.00 Max = 71.00, μ = 10.59. The average citation per items was 4.74 (ACP = 4.74) h-index=60, sum of times cited (STC = 39,572), citing articles (CA = 32,749) without self-citations (n =36,042) and citing articles (CA= 30,777). The findings suggest that researchers have yet to establish the nexus between information management and its impact in promoting indigenous use of natural remedies within public healthcare to promote its efficacy.
Construction of a 56 mm aperture high-field twin-aperture superconducting dipole model magnet

A twin-aperture superconducting dipole model has been designed in collaboration with Finnish and Swedish Scientific Institutions within the framework of the LHC R&D programme and has been built at CERN. Principal features of the magnet are 56 mm aperture, separate stainless steel collared coils, yoke closed after assembly at room temperature, and longitudinal prestressing of the coil ends. This paper recalls the main dipole design characteristics and presents some details of its fabrication including geometrical and mechanical measurements of the collared coil assembly.
Randomized algorithms for quadratic stability of quantized sampled-data systems

We present a novel development of randomized algorithms for quadratic stability analysis of sampled-data systems with memoryless quantizers. The specific randomized algorithm employed generates a quadratic Lyapunov function and leads to realistic bounds on the performance of such systems. A key feature of this method is that the characteristics of quantizers are exploited to make the algorithm computationally efficient.
The MOGREPS short‐range ensemble prediction system

The Met Office has recently introduced a short‐range ensemble prediction system known as MOGREPS. This system consists of global and regional ensembles, with the global ensemble providing the boundary conditions and initial‐condition perturbations for the regional ensemble. Perturbations to the initial conditions are calculated using the ensemble transform Kalman filter, which is a computationally‐efficient version of the ensemble Kalman filter. Model uncertainties are represented in the system through a series of schemes designed to tackle the structural and subgrid‐scale sources of model error.
The influence of vibration on Marangoni waves in two-layer films

Abstract The influence of time-periodic vibrations on long Marangoni waves in two-layer films is investigated. The problem is governed by a system of nonlinear equations obtained in the framework of the lubrication approximation. Periodic boundary conditions are applied on the boundaries of the computational region. The development of instabilities is investigated by means of nonlinear simulations. Excitation of two-dimensional and three-dimensional subharmonic wavy regimes is studied. A new phenomenon, the excitation of nonlinear waves with a temporal period that is four times larger than that of the gravity modulation, is revealed.
Coded photoacoustic Doppler excitation with near-optimal utilization of the time and frequency domains

We propose and experimentally demonstrate a new photoacoustic (PA) excitation and analysis method which achieves an almost complete utilization of the available time and frequency windows. The method, which enables spectral and spatial characterization of flow, is based on interleaving tens of tone-burst sequences at equally spaced frequencies. Depending on the application, the interleaved signals can be generated by a single optical source or by multiple sources, possibly at different wavelengths. Upon reception, the responses corresponding to the different tone-burst sequences are spectrally de-multiplexed. As demonstrated in the current work, this method can be used to improve the SNR of PA systems based on optical sources with limited peak power. Alternatively, if the interleaved excitation signals are at different wavelengths, the PA responses can be used for multispectral characterization of the medium.
The Information Content of the Elastic Reflection Matrix

SUMMARY The P-SV reflection matrix for a plane interface between two elastic media depends on the density, P-wave velocity and S-wave velocity of the two media. When the reflection matrix is given as a function of slowness, five parameters—the ratio between the two densities, and P- and S-wave velocities for the two media—can theoretically be estimated. When the reflection matrix is given as a function of the angle of incidence for P waves, only the density ratio and three velocity ratios can be estimated. A numerical sensitivity analysis is performed on modelled data to determine how the different parameters contribute to the information content of the reflection matrix. It is confirmed that, theoretically, five parameters can be estimated from the PP reflection coefficient as a function of slowness, when the slowness varies from zero to some maximum value. However, certain linear combinations of the parameters are very poorly determined. These are the parameters associated with the eigenvectors of the Hessian matrix (or the normalized Fisher information matrix) corresponding to the smallest eigenvalues. A maximum of three parameters can be estimated from the PP reflection coefficients when only pre-critical data are used, and up to five when post-critical data are included. the analysis shows that the best-determined parameter from the PP-reflection coefficients is the gradient of the P-wave impedance, whereas the best-determined parameter from the PS-, SP- and SS-reflection coefficients is the gradient of the S-wave impedance. the second best parameters for all reflection coefficients are linear combinations of the two S-wave velocities and the density ratio. the sum of the two S-wave velocities is very poorly determined
Use of Annular Apertures to Increase Focal Depth

A theoretical study is made of the possibilities of using an annular aperture to increase the focal depth of a photographic objective. It is shown that for a given gain in focal depth the loss in speed is the same for both annular apertures and conventional stopping down. For images of isolated point objects, the definition is improved by using an annular stop. The gain in focal depth is less for off-axis points, but it is found that, for example, a factor of 2.7 in focal depth gained by means of an annular aperture is barely affected at a field angle of 30°.
T Design of Dual Input Power System Stabilizer for Detailed Dynamic Model of Power System

The paper deals with design of dual input power system stabilizer for single machine infinite bus (SMIB) system considering detailed dynamic model of the system including turbine-governor dynamics. IEEE type PSS2B model of the dual input power system stabilizer, is considered for present study. It comprises of two blocks, e.g., signal processing block and lead-lag network block with crucial design parameters as stabilizing gain constant, Ks1, lead time constant, T1, and lag time constant, T2. These parameters are optimized using a new hybrid optimization technique. Studies were carried out to understand the effect of optimum dual input power system stabilizer on simplified as well as detailed dynamic models of SMIB system. Investigations reveal that the dual input power system stabilizer with optimum parameters obtained considering simplified dynamic model of SMIB system works well on the actual system i.e., detailed dynamic model of system.
An optimum time scale for discrete Laguerre network

Any discrete-time stable transfer function can be expressed by a discrete-time Laguerre series with a chosen time scale. An optimum time scale such that an index is minimized is derived. This index ensures that the coefficients of higher-order Laguerre functions go toward zero quickly. The solution derived requires the knowledge of the impulse response of the discrete plant. Cases of first-order plants, second-order underdamped plants, and plants with multiunit delay are also discussed. >
A Multiscale Four-Dimensional Data Assimilation System Applied in the San Joaquin Valley during SARMAP. Part I: Modeling Design and Basic Performance Characteristics

Abstract This paper presents results of numerical simulations made with a high-resolution multiscale four-dimensional data assimilation system applied over California during two episodes associated with high ozone concentrations in the San Joaquin Valley. The model used here is the nonhydrostatic Pennsylvania State UniversityNational Center for Atmospheric Research Mesoscale Model (MM5). The focus of the paper is the objective validation of the regional (mesoalpha scale) meteorological results. The mulliscale data assimilation approach produces highly reliable simulations of the wind, temperature, mixed-layer depth, and moisture, each of which is vital to air quality modeling and a host of other mesoscale applications. The significance of this research is threefold. First, it is the first evaluation of this multiscale assimilation system in strongly heated summertime conditions and with comparatively fine grid resolution (4-km inner mesh). Second, the assimilation system has been extended so that tempera.
Ultrafast two-dimensional terahertz spectroscopy of elementary excitations in solids

Recent experimental progress has allowed for the implementation of nonlinear two-dimensional (2D) terahertz (THz) spectroscopy in the ultrafast time domain. We discuss the principles of this technique based on multiple phase-locked electric field transients interacting in a collinear geometry with a solid and the phase-resolved detection of the THz fields after interaction with the sample. To illustrate the potential of this new method, 2D correlation spectra of coupled intersubband-longitudinal optical phonon excitations in a double quantum well system and a study of ultrafast carrier dynamics in graphene are presented.
Convergence of SPH and AMR simulations

Abstract We present the first results of a large suite of convergence tests between Adaptive Mesh Refinement (AMR) Finite Difference Hydrodynamics and Smoothed Particle Hydrodynamics (SPH) simulations of the non-linear thin shell instability and the Kelvin-Helmholtz instability. We find that the two methods converge in the limit of high resolution and accuracy. AMR and SPH simulations of the non-linear thin shell instability converge with each other with standard algorithms and parameters. The Kelvin-Helmholtz instability in SPH requires both an artificial conductivity term and a kernel with larger compact support and more neighbours (e.g. the quintic kernel) in order converge with AMR. For purely hydrodynamical problems, SPH simulations take an order of magnitude longer than the grid code when converged.