Miracle-dz/UniFAR-FTUs huggingface dataset:
Two-dimensional induction in a thin sheet of variable integrated conductivity at the surface of a uniformly conducting earth

Summary. The forward solution of the general two-dimensional problem of induction in a model earth comprising a uniformly conducting half-space covered by a thin sheet of variable idegrated conductivity is obtained. Unlike some previous treatments of similar problems, the method presented here does not require the field to be separated into its normal and anomalous parts. Both the E- and B-polarization modes of induction are considered and in each case the solution is expressed in terms of the horizontal component of the electric field satisfying, on the surface of the conductor, a singular integral equation whose kernel is a well-known analytic function. A recently published solution of the coast effect is included as a special case. The numerical procedure for solving the integral equations is described and some illustrative calculations are presented.
Interpreting the Principal Component Analysis of Multivariate Density Functions

Functional principal component analysis (FPCA) as a reduction data technique of a finite number T of functions can be used to identify the dominant modes of variation of numeric three-way data. We carry out the FPCA on multidimensional probability density functions, relate this method to other standard methods and define its centered or standardized versions. Grounded on the relationship between FPCA of densities, FPCA of their corresponding characteristic functions, PCA of the MacLaurin expansions of these characteristic functions and dual STATIS method applied to their variance matrices, we propose a method for interpreting the results of the FPCA of densities. This method is based on the investigations of the relationships between the scores of the FPCA and the moments associated to the densities. The method is illustrated using known Gaussian densities. In practice, FPCA of densities deals with observations of multidimensional variables on T occasions. These observations can be used to estimate the T associated densities (i) by estimating the parameters of these densities, assuming that they are Gaussian, or (ii) by using the Gaussian kernel method and choosing the matrix bandwidth by the normal reference rule. Thereafter, FPCA estimate is derived from these estimates and the interpretation method is carried out to explore the dominant modes of variation of the types of three-way data encountered in sensory analysis and archaeology.
Wave environment inside an inverted‐V electron event observed by Freja

We present an analysis of the wave environment observed inside an inverted-V electron event at an altitude of 1700 km, occurring in the upward directed current with intensity of a few µAm−2. During the analyzed event we observe that precipitating auroral electrons (∼ 2 keV) generate intense (40 mV/m) auroral hiss with peak power concentrated at the lower hybrid frequency flh ≈ fpi, and weak Langmuir waves at fpe. The low frequency turbulence observed within the event is found to be composed of a mixture of Alfven waves, O+ cyclotron waves, multi-ion resonances, and ion sound waves. The LH waves appear to interact modulationally with O+ and ion sound waves. From the observed values of flh and multi-ion resonance frequencies it is possible to estimate three-ion composition of plasma with representative values of [23, 19, 58] percent for normalized number densities of [H+, He+, O+], respectively.
Structural Balance: A Dynamic Perspective

The paper presents results derived from a series of simulations of signed networks (i.e., networks containing positive and negative links) subject to a balancing process. The dynamics are followed in a space defined by variations in the proportion of positive links introduced and the tolerance to imbalance. The authors claim to have discovered boundaries in the space separating it into three distinct regions. One region probably displays the characteristics of self-organized criticality, which may have implications for the theory of extreme events.
Three-dimensional finite element modelling for consolidation due to groundwater withdrawal in a desaturating anisotropic aquifer system

A poroelastic numerical model is presented to evaluate three-dimensional consolidation due to groundwater withdrawal from desaturating anisotropic porous media. This numerical model is developed based on the fully coupled governing equations for groundwater flow in deforming variably saturated porous media and the Galerkin finite element method. Two different cases of unsaturated aquifers are simulated for the purpose of comparison: a cross-anisotropic soil aquifer, and a corresponding isotropic soil aquifer composed of a geometrically averaged equivalent material. The numerical simulation results show that the anisotropy has a significant effect on the shapes of three-dimensional hydraulic head distribution and displacement vector fields. Such an effect of anisotropy is caused by the uneven partitioning of the hydraulic pumping stress between the vertical and horizontal directions in both groundwater flow field and solid skeleton deformation field. Copyright © 1999 John Wiley & Sons, Ltd.
Chebyshev representation for rational functions

An eective representation is obtained for rational functions all of whose critical points, apart from g 1, are simple and their corresponding critical values lie in a four-element set. Such functions are described using hyperelliptic curves of genus g > 1. The classical Zolotarev fraction arises in this framework for g = 1. Bibliography: 8 titles.
Interactions between two deformable droplets in tandem subjected to impulsive acceleration by surrounding flows

Abstract The dynamics of two deformable drops placed in tandem and subjected to a sudden acceleration by a gaseous flow is investigated. A finite-volume scheme coupled with the method of moving mesh interface tracking is employed. The unsteady interactions between the droplet pair are studied by varying the minimum initial separation distance (${d}_{0} $) from $0. 6{r}_{0} $ to $10{r}_{0} $ with ${r}_{0} $ being the radius of the initial spherical droplets. The influence of the interactions on the droplet dynamics is examined by comparing with the case of a single isolated droplet at three initial Weber numbers ${\mathit{We}}_{s, 0} $ of 40, 4 and 0.4. The computations show that for small initial separation distances the dynamics of the downstream droplet is significantly affected by the presence of the upstream droplet. A mushroom shape is formed by the droplet pair at the two largest Weber numbers, while the two drops experience small deformation and shape oscillations at ${\mathit{We}}_{s, 0} = 0. 4$. The drag coefficient of the downstream droplet is dramatically reduced, especially for the two largest Weber numbers with smaller initial separation distances due to the sheltering effects, while the drag force of the upstream drop is slightly decreased. For the cases with smaller ${d}_{0} $, a thin film is formed between the two drops at the later stages, and this leads to a sudden increase in the drag of the trailing drop, but a sharp reduction in the drag of the leading drop.
Response to ultrasound of two types of lipid-coated microbubbles observed with a high-speed optical camera

Microbubbles (MBs) can be coated with different lipids, but exact influences on acoustical responses remain unclear. The distribution of lipids in the coating of homemade MBs is heterogeneous for DSPC and homogeneous for DPPC-based MBs, as observed with 4Pi confocal microscopy. In this study, we investigated whether DSPC and DPPC MBs show a different vibrational response to ultrasound. MBs composed of main lipid DSPC or DPPC (2 C-atoms less) with a C4F10 gas core, were made by sonication. Microbubble spectroscopy was performed by exciting single MBs with 10-cycle sine wave bursts having a frequency from 1 to 4 MHz and a peak negative pressure of 10, 20, and 50 kPa. The vibrational response to ultrasound was recorded with the Brandaris 128 high-speed camera at 15 Mfps. Larger acoustically induced deflation was observed for DPPC MBs. For a given resting diameter, the resonance frequency was higher for DSPC, resulting in higher shell elasticity of 0.26 N/m as compared to 0.06 N/m for DPPC MBs. Shell viscosity was similar (~10-8 kg/s) for both MB types. Non-linear behavior was characterized by the response at the subharmonic and second harmonic frequencies. More DPPC (71%) than DSPC MBs (27%) showed subharmonic response, while the behavior at the second harmonic frequency was comparable. The different acoustic responses of DSPC and DPPC MBs are likely due to the choice of the main lipid and the corresponding spatial distribution in the MB coating.
Study on Microscopic Mechanism for Sand Particles Lift-Off

Smoothed particle hydrodynamics (SPH) method is used to simulate the lift-off phenomenon of sand particles in the air flow. Whether the sand particles make any form of movement in the air flow, firstly, they always jump into the air from a standstill condition, so it is helpfull to understand the saltation mechanism of sand particles. Because the computitional region is discreted into particles in the SPH method, the movement of each particle can represent the machnical behavior of sand particles if the particle dispersion has the same characteristic with the sand particles. The foundmental theory of SPH method and its key elements are reviewed in detail, such as the kernel function, the choice of smoothing length and their influence on the numerical simulation results.In this study a numerical simulation model of wind-blown sand two-phase flow using SPH model is proposed and then the model is discreted to simulate the take-off process of sand particles with adquate boundary conditions. Simulation results show that the proposed model can be used to simulate the dynamic characteristics of sand particles in lift-off.
Derivations for the chunking model

Abstract The chunking model is an extension of TODAM which uses multiple convolutions, n -grams (autoconvolutions of sums of item vectors), and chunks (sums of n -grams) to explain serial organization in a distributed memory. This paper presents the necessary derivations to compute signal-to-noise ratios in terms of the standard TODAM parameters, Quantitative applications of the model to a variety of memory tasks involving recognition, recall, and redintegration are now possible, and a number of implications of the analysis are briefly discussed.
Siegel-Whittaker Functions on Sp(2,R) for Principal Series Representations

We study a kind of generalized spherical functions on Sp(2, R) for principal series representations, which are related to archimedean theory of automorphic forms (Siegel wave forms). By solving some differential equations, we obtain explicit formulas for boundary values of these functions in terms of Meijer's G-functions.
Estimating the correlation properties of k-distributed SAR clutter

The authors extend previous analysis of the texture properties of k-distributed SAR clutter by including spatial correlation properties. Throughout they compare operating in the intensity domain with using its logarithm or square root (amplitude). Initially they derive the variance of the correlation coefficients in the three domains, assuming a negative exponential texture autocorrelation function (ACF), and demonstrate the advantage of both the log and amplitude domains over the intensity. In addition it is shown that a normalised estimator yields a further reduction in the variance. Finally, the results are combined in a derivation of the errors in the correlation length obtained by fitting the correlation coefficients to an assumed exponential autocorrelation function.
High-precision refractometry by hologram interferometry

The refractive index of an optical glass sample in the form of a wedge is measured by comparison with that of a reference liquid. This holographic technique can also be applied to the measurement of the refractive index of the immersion liquid, if the refractive index of the glass wedge is known. The accuracy ofthe method with respect to index matching, glass wedge preparation, and fringe position measurement on the interferogram is discussed.
The spatial structure of neutral atmospheric surface-layer turbulence

Modelling of the complete second-order structure of homogeneous, neutrally stratified atmospheric boundary-layer turbulence, including spectra of all velocity components and cross-spectra of any combination of velocity components at two arbitrarily chosen points, is attempted. Two models based on Rapid Distortion Theory (RDT) are investigated. Both models assume the velocity profile in the height interval of interest to be approximately linear. The linearized Navier–Stokes equation together with considerations of ‘eddy’ lifetimes are then used to modify the spatial second-order structure of the turbulence. The second model differs from the first by modelling the blocking by the surface in addition to the shear. The resulting models of the spectral velocity tensor contain only three adjustable parameters: a lengthscale describing the size of the largest energy-containing eddies, a non-dimensional number used in the parametrization of ‘eddy’ lifetime, and the third parameter is a measure of the energy dissipation. Two atmospheric experiments, both designed to investigate the spatial structure of turbulence and both running for approximately one year, are used to test and calibrate the models. Even though the approximations leading to the models are very crude they are capable of predicting well the two-point second-order statistics such as cross-spectra, coherences and phases, on the basis of measurements carried out at one point. The two models give very similar predictions, the largest difference being in the coherences involving vertical velocity fluctuations, where the blocking by the surface seems to have a significant effect.
Analysis of Coupled Nonuniform Transmission Lines Using Short Exponential or Linear Sections

A method is proposed to analyze arbitrary coupled Nonuniform Transmission Lines (NTLs). First, the modal decomposition approach is used to decouple the sets of differential equations. Then, the modal lines are subdivided to several homogeneous nonuniform sections. The variations of the nonuniform sections are considered exponential or linear. The ABCD parameters of modal lines and finally the S parameters of the whole coupled NTL are obtained. The accuracy of the method is studied using a comprehensive example.
Stationary Subdivision and Multiresolution Surface Representations

Stationary subdivision is an important tool for generating smooth free-form surfaces used in CAGD and computer graphics. One of the challenges in the construction of subdivision schemes for arbitrary meshes is to guarantee that the surfaces produced by the algorithm are $C\sp1$-continuous. First results in this direction were obtained only recently. In this thesis we derive necessary and sufficient criteria for $C\sp{k}$-continuity that generalize and extend most known conditions. We present a new method for analysis of smoothness of subdivision which allows us to analyze subdivision schemes which do not generate surfaces admitting closed-form parameterization on regular meshes, such as the Butterfly scheme and schemes with modified rules for tagged edges. The theoretical basis for analysis of subdivision that we develop allows us to suggest methods for constructing new subdivision schemes with improved behavior. We present a new interpolating subdivision scheme based on the Butterfly scheme, which generates $C\sp1$-continuous surfaces from arbitrary meshes. We describe a multiresolution representation for meshes based on subdivision. Combining subdivision and the smoothing algorithms of Taubin, allows us to construct a set of algorithms for interactive multiresolution editing of complex hierarchical meshes of arbitrary topology.
Ultraviolet photoproduction of ISM dust Laboratory characterisation and astrophysical relevance

The production of a hydrogenated amorphous carbon polymer (a-C:H) via the photolysis of a series of organic molecule precursors at low temperature is described. Such amorphous material is synthesised under interstellar conditions (10 K and Lyman-α photons) and represents the best candidate to explain the Diffuse Interstellar Medium absorption observed in our Galaxy and in other galaxies. We perform a series of laboratory analyses (Infrared spectroscopy, µspectroscopy, Raman, Photoluminescence and UV-visible spectroscopy) which allow a full characterisation of such polymers. This allows us to assess the importance of the polymer and possible scenarios for its role in crucial aspects of the lifecycle of dust. Such material has implications for the carbon budget at galactic scales, hydrogen formation, extended red emission, as a PAH precursor, and in explaining the 2175 A extinction bump.
Precise edge detection: representation by Boolean functions, implementation on the CNN

An edge detection problem is considered in the paper. It is proposed to reduce the edge detection problem on binary images to evaluation of the Boolean functions. A separate processing of the binary planes with their further integration into resulting image is used for edge detection on the gray-scale images. The different Boolean functions for detection of edges corresponding to the upward and downward brightness overleaps, to the narrow directions (south-north, south-east-north-west, etc.) are considered. All the processing functions are non-threshold Boolean functions of nine variables (such a number of variables corresponds to the processing within a 3/spl times/3 local window around the each pixel). Since all the functions are not threshold, CNN with universal binary neurons are proposed to be used for their implementation. The weighting templates for all functions are obtained by learning. The software simulation results are also presented.
An Automated Approach to the Study and Classification of Colliding and Interacting Galaxies

Colliding galaxies are perhaps the greatest events changing and evolving our Universe. Consequently, the need for an understanding of how that interaction originated is very important. This thesis presents a framework in which the study of these events can be conducted in a timely and efficient manner. A genetic algorithm coupled with an initial conditions generator, a physics engine and an analysis package performs an automated search to visually match an unknown galactic interaction with a known event, thus providing the starting conditions that created such an interaction.
Path planning for satellite slew manoeuvres: a combined flatness and collocation-based approach

Path planning for satellite slew manoeuvres is considered as an optimal control problem. The goal is to design rapid manoeuvres with the resting time vibrational modes as short as possible in order to provide more time for space imagery. This problem of optimal time and control effort is addressed using differential flatness and B-spline collocation. The flatness allows for reformulating the original optimal control problem as a tractable geometric programming problem with no numerical integration, and with a minimal number of decision variables. A direct consequence of flatness is that the transformed constraints describe generally a non-convex subspace. In the proposed approach, a flat suboptimal convex problem is derived by means of offline convex approximations of the feasible space and a measure of its conservatism is given. Numerical results are discussed and compared with the results generated from an in-service industrial path planner available at the French Space Agency, CNES.
Direct writing of fluorescent patterns on LiF films by x-ray microprobe

Fluorescent patterns with submicron dimensions have been obtained by creating stable F3+ and F2 color centers in LiF films using a focused x-ray beam provided at the ELETTRA synchrotron radiation facility. The patterns were written by scanning the LiF specimen with respect to the x-ray microprobe. In these attempts, using an x-ray microspot with a diameter of 100 nm and a flux density ⩾109 photons/s, we generated ∼500-nm-wide lines efficiently emitting in the visible spectral region when excited by blue light at 458 nm. Preliminary results indicate that the spectral distribution of the emitted luminescence can be changed by varying the photon dose delivered to the sample.
On Stellar Coronae and Solar Active Regions

Based on Yohkoh Soft X-Ray Telescope (SXT) observations of the Sun near peak activity level obtained on 1992 January 6, we search for coronal structures that have emission measure distributions EM(T) that match the observed stellar coronal emission measure distributions derived for the intermediate-activity stars ϵ Eri (K2 V) and ξ Boo A (G8 V) from Extreme Ultraviolet Explorer spectroscopic observations. We find that the temperatures of the peaks of the observed stellar distributions EM(T), as well as their slopes in the temperature range 6.0 ≲ log T ≲ 6.5, are very similar to those obtained for the brightest of the solar active regions in the 1992 January 6 SXT images. The observed slopes correspond approximately to EM ∝ Tβ with β ~ 4, which is much steeper than predicted by static, uniformly heated loop models. Plasma densities in the coronae of ϵ Eri and ξ Boo A are also observed to be essentially the same as the plasma densities typical of solar active regions. These data provide the best observational support yet obtained for the hypothesis that solar-like stars up to the activity levels of ϵ Eri (K2 V) and ξ Boo A are dominated by active regions similar to, though possibly considerably larger than, those observed on the Sun. The surface filling factor of bright active regions needed to explain the observed stellar emission measures is approximately unity. We speculate on the scenario in which small-scale "nanoflares" dominate the heating of active regions up to activity levels similar to those of ϵ Eri (K2 V) and ξ Boo A. At higher activity levels still, the interactions of the active regions themselves may lead to increasing flaring on larger scales that is responsible for heating plasma to the observed coronal temperatures of T ≳ 107 K on very active stars. Observations of X-ray and EUV light curves using more sensitive instruments than are currently available, together with determinations of plasma densities over the full range of coronal temperatures (106-107 K and higher), will be important to confirm flare heating hypotheses and to elicit further details concerning coronal structures at solar-like active region temperatures (T ≲ 5 × 106 K) and the temperatures that characterize the most active stars (T ≳ 107 K).
A new structuring element for multi-scale morphology analysis and its application in rolling element bearing fault diagnosis

The condition monitoring and fault diagnosis of rolling element bearings play an important role in the safe and reliable operation of rotating machinery. Feature extraction based on vibration signals is an effective means to identify the operating condition of rolling element bearings. Methods based on multi-scale mathematical morphology (MM) have recently been developed to extract features from one-dimensional signals. In this paper, a new double-dot structuring element (SE) is constructed for multi-scale MM. A pattern spectrum, obtained from the multi-scale MM, is used as a feature extraction index. A correlation analysis gives the final identification result by utilizing information over a whole pattern spectrum. Compared with the most commonly used flat SE, the double-dot SE can extract more features of original signals at different scales. Vibration signals, measured from defective bearings with outer race faults, inner race faults and ball faults, are used to evaluate the fault detection ability of the proposed SE and bearing fault diagnosis method. Results show that faults at different levels can be identified, including ball fault; and the location of outer race fault can also be differentiated.