Miracle-dz/UniFAR-FTUs huggingface dataset:
Could the Lunar “Late Heavy Bombardment” Have Been Triggered by the Formation of Uranus and Neptune?

We investigate the hypothesis that the so-called Late Heavy Bombardment (LHB) of the Moon was triggered by the formation of Uranus and Neptune. As Uranus and Neptune formed, which we assume occurred at the epoch of the LHB, they scattered neighboring icy planetesimals throughout the Solar System. Some of these objects hit the Moon. Our integrations show that the Moon would have accreted about 6×1021 g, if we assume that the Uranus–Neptune region initially contained 5 times the current mass of these planets in the form of small solid objects. In addition, Mars would have accumulated ∼6×1022 g of icy material, which could have supplied its putative early massive atmosphere. However, Earth would likely have accreted only ∼7×1022 g of water, or ∼5% of its oceans, through the mechanisms studied here. The numerical experiment that we have performed on the behavior of Uranus–Neptune planetesimals shows very good agreement with current constraints on the LHB. The influx of Uranus–Neptune planetesimals onto the Moon could have lasted for a time as short as 10 or 20 million years. The dynamical transport of the Uranus–Neptune planetesimals during this process would have caused Jupiter and Saturn to migrate. This migration, in turn, would have destabilized objects in the jovian Trojan swarms and the asteroid belt. Thus, not only would Uranus and Neptune planetesimals have struck the Moon, but asteroids would have as well. We find that the Trojan asteroids of Jupiter could not have contributed a large percentage of material to the LHB, but the asteroid belt could, in principle, have contributed to, or even dominated, the LHB. Although this model appears to explain the LHB well, it requires that fully formed Uranus and Neptune not appear in the trans-saturnian region until some 700 million years after the formation of the Earth.
ECG data compression using the discrete cosine transform (DCT)

Orthogonal transforms provide alternate signal representations that can be useful for electrocardiogram (ECG) data compression. The goal is to select as small a subset of the transform coefficients as possible which contain the most information about the signal, without introducing objectionable error after reconstruction. With a sampling rate of 1 kHz, more than 99% of the power in the DCT is contained within the first 20% of the coefficients. Despite this result a 5:1 compression ratio cannot be obtained by merely substituting zero for the remaining 80%. The coefficients after the first 20%, although of relatively small magnitude, preserve the DC integrity of the signal. Approximating these components as zero leads to introduction of spurious sinusoidal terms in the reconstructed signal. A quantization technique to better approximate the higher coefficients has been used to obtain an accurate representation of the signal. The tradeoffs between accuracy, speed, and compression ratio are discussed. <<ETX>>
Complexity models in financial markets

In this approach, the complexity of the self-organizing microstructure of the stock exchange is explicitly taken into consideration: the process of offers and trades as well as the adjustment of individual expectations are modelled with help of a (stochastic) jump process. Its abilities are illustrated by modelling the continuous quotations of asset prices at an auction type stock exchange. The functional form of the transition (hazard) rates is chosen to reflect the individual preferences and expectations as well as the economic environment. The model is described in detail and examples of Monte Carlo simulation results are presented.
Microflares to megaflares: Solar observations and modeling

Abstract The observationally determined properties of solar flares such as overall energy budget and distribution in space, time and energy of flare radiation, have improved enormously over the last cycle. This has enabled precision diagnostics of flare plasmas and nonthermal particles in large and small events, informing and driving new theoretical models. The theoretical challenges in understanding flare are considerable, involving MHD and kinetic processes operating in an environment far from equilibrium. New observations have also provided some challenges to long-standing models of flare energy release and transport. This talk overviewed recent observational and theoretical developments, and highlighted some important questions for the future
TOWARDS A LOGICAL RECONSTRUCTION OF A THEORY FOR LOCALLY COMPLETE DATABASES

A relational database stores information about the world. In order to describe how reliable the content of a database is with respect to a certain domain, two cardinal concepts are generally used: correctness and completeness. Correctness refers to whether the database stores only true facts about its intended domain or if it possibly contains false data. Completeness refers to whether the database stores all the information that is true in the world under consideration or not. In this work we study databases that store correct but possibly incomplete information about the world. In particular, we investigate what we call locally complete databases. These are databases that may be complete about certain parts of the world, while being incomplete in general. Such databases consist of a standard relational database supplemented with a number of specifications, called local closed world assumptions, of the areas in the real world where the database contains all true tuples. Our study of locally complete databases is divided into three parts. In the first part we investigate how to represent the fact that a relational database is locally complete. For this purpose we extend the idea of a window of expertise of a database predicate to the first-order case. At the reasoning level, we study two important reasoning tasks: computing answers to queries and determining whether a database has complete knowledge on a query. In the second part of the thesis we study methods to perform efficient computation of the reasoning tasks described above. In particular, we present approximate methods for query answering. We prove that for a useful class of queries and locally complete databases these methods are tractable and complete. The third and last part of the thesis deals with extending the query language from standard SQL to queries with modalities. This extension will allow us to retrieve useful information about the knowledge endorsed by a locally complete database. In this part, we also present a prototype of this extension, based on the model expansion system IDP.
Turbulent shear flows over low hills

A general analysis is developed for turbulent shear flows over two- and three-dimensional hills with low-slopes which allows for a wide range of upwind velocity profiles, such as those caused by wakes of upwind hills, roughness changes, or changes in stratification. In this paper the atmosphere is assumed to be neutrally stable and the half-lengths of the hills, L, are large compared with their heights, H, which are very large compared with the roughness length zo. The general structure of the solution is defined by dividing the flow into two regions, each of which is divided into two sublayers: an inviscid outer region composed of an upper layer in which there is potential flow when the atmosphere is neutrally stable, and a middle layer in which the wind shear dominates; and an inner region of thickness l ≤ L in which the effects of perturbation shear stresses are confined. The latter region is divided into two: a shear stress layer where the shear stresses, although weak, determine that the maximum of the perturbation velocity is located in this layer; and an inner surface layer of thickness ls where the shear stress gradient varies rapidly and the perturbation velocity tends to zero. The details of the middle layer are given here for different kinds of upwind profiles, including logarithmic, ‘power law’ and linear profiles. It is shown that the analysis can be extended to allow for nonlinear inertial effects in the middle layer. Analytical solutions are derived for the inner region as asymptotic expansions in δ = [ln(l/zo)]−1, which is assumed to be small, and this shows that ls ∼ zo(l/zo)1/2. The results of the analytical model are compared with our own and with previously published numerical computations of the full equations (applying the same assumptions used for calculating the turbulent shear stresses as used in the analytical work), which have largely been validated against full-scale measurements. These results confirm that the relative increase of surface stress is significantly greater than the increase of wind speed near the surface except when there is no upwind shear (as for example in a logarithmic boundary layer when the roughness length tends to zero). Finally, the paper shows that the outer regions of laminar (or constant eddy viscosity) and of turbulent flows over hills are broadly similar, but that the effects of the flow in the inner region on the outer regions are much smaller in the latter case.
The Refractive Index in Electron Optics and the Principles of Dynamics

In view of mis-statements made in the literature, the origin of the refractive index in electron optics is discussed in some detail, and the uniqueness of an expression previously given is demonstrated. On this basis, some general properties of electron optics are investigated. A relation between ray direction and wave normal is obtained. Whereas the refractive index is unique in terms of the magnetic vector potential A, this itself is arbitrary to some extent. It is shown that A must, for purposes of electron optics, be chosen so as to satisfy Stokes' theorem and that, if it does, no observable effects result from the arbitrariness of A. An expression for the optical path difference is given in terms of the magnetic flux enclosed. The results are applied to a number of questions, viz. the differential equations for trajectories, the focusing properties of an axially symmetric field and the interference pattern produced by two converging bundles of rays which enclose a magnetic flux.
Nonoscillation of third order retarded equations

The third order delay equation y‴(t) + a(t)yτ(t) = 0 is studied for its nonoscillatory nature under the general condition in which a(t) has been allowed to oscillate. It is shown by way of a differential inequality that if g(t) is a thrice differentiable and eventually positive function then g‴(t) + t2|a(t)|g(t) ≤ 0 is sufficient for this equation to have bounded nonoscillatory solutions.
A NEW APPROACH TO ASTROPHYSICAL SPECTRA: THE COMPLETE EXPERIMENTAL SPECTRUM OF ETHYL CYANIDE (CH3CH2CN) BETWEEN 570 AND 645 GHZ

There is a general consensus that many of the unidentified features in astrophysical spectra are due to low lying excited vibrational and torsional states of a few molecules—commonly referred to as the astrophysical weeds. This is a challenging spectroscopic problem not only because there are many such states, but also because these states are often highly perturbed and difficult to analyze. We have previously described an alternative approach based on experimental, intensity-calibrated spectra taken at many temperatures. In this paper, we describe the procedures and results obtained with this approach for ethyl cyanide, strategies for archiving and disseminating these results, and the prospects for using these results to reduce the confusion limit in the powerful new observatories that are coming online.
Oxygen λ7771–5 Triplet in Hyades A-Type Stars: A Quest for the Key to the Am Phenomenon

An extensive profile-fitting analysis of the OI 7771-5 triplet (along with the nearby Fe I line) was carried out for thirty-one A-type stars, eighteen of them belonging to the Hyades group, in order to clarify the key factor which plays the decisive role in the appearance of abundance anomalies of metallic-line stars (Am), by examining whether any meaningful relation exists between the microturbulence (£), the oxygen abundance (logeo), the iron abundance (logepe), the projected rotational velocity (ve sini), and the stellar atmospheric parameters. It was clearly found based on the Hyades results that the abundance of O/Fe, both being good indicators of the Am phenomenon, because of the negative/positive correlation with the metallicity estimated from colors, progressively increases/decreases (i.e., toward the direction of disappearance of anomaly) with an increase in vesini as well as with a decrease in logg. It was thus concluded that the most important driver of the Am phenomenon, producing a significant deficiency/excess of O/Fe, is the rotational velocity which appears to be responsible for not only the triggering, but also the extent of the peculiarity. Meanwhile, the observed log #-dependence of the abundance anomalies is considered to be nothing but superficial, which may be interpreted as being due to the correlation between logg and ve sini, i.e., rotation-induced lowering of the effective gravity.
The Green's Function and its Oscillatory Properties for a Single Branch Structure of a Pinned Beam-Rod System

This paper concerns the determination of qualitative properties of linear vibrational systems, in particular for a single branch structure consisting of a pinned beam-rod system. First, we establish the characteristic equations satisfied by the Green’s function for this structure. The Green’s functions corresponding to support conditions where the left end of the beam was pinned-end are deduced by adopting the direct integral method. Using the theory of oscillation kernels established by Gantmakher and Krein, oscillatory properties of the Green's function for the beam-rod system are proved. Furthermore, four oscillation properties associated with frequencies and mode functions for the system are given.
The Dynamics of Eye Formation and Maintenance in Axisymmetric Diabatic Vortices

Abstract This paper investigates the occurrence, formation, and maintenance of eyes in idealized axisymmetric balanced vortices with diabatic forcing. Two key elements of the model setup are temperature relaxation toward a specified equilibrium temperature Te and Ekman pumping from a turbulent boundary layer. Furthermore, the flow is assumed to be almost inviscid in the interior. The model does not attempt any closure for moist convection. Previous work by the authors has shown that there is a continuous transition from monsoonlike vortices to hurricane-like vortices. This transition is governed by the ratio F = αT /cD, where αT is the thermal relaxation rate and cD the surface drag coefficient. An eye is defined in terms of the vertical wind with maximum upwelling occurring at some finite radius rather than at the origin. It is possible to obtain an eye even though Te maximizes at the origin, that is, even though Te does not directly predispose upwelling at some finite radius. The occurrence of an eye is.
Multivariable adaptive actuator compensation with partially known high frequency gain matrix

To design an adaptive control scheme for a multivariable plant with unknown actuator nonlinearities at the input of a linear dynamics, it is important to use less a priori knowledge of the high frequency gain matrix of the linear dynamics. To solve this issue, this paper presents an adaptive control scheme, using only partial knowledge of the high frequency gain matrix. Such an adaptive control scheme employs a multivariable adaptive inverse to cancel the actuator nonlinearities and leads to stable parameter adaptation. It is also shown that the required high frequency gain matrix knowledge for an adaptive inverse design is also necessary if a quadratic gradient algorithm is used for adaptation.
A Kolmogorov–Smirnov-Type Test for Shortfall Dominance Against Parametric Alternatives

This article introduces a Kolmogorov-type test for the shortfall order (also known in the literature as the right-spread or excess-wealth order) against parametric alternatives. In the case of the null hypothesis corresponding to the negative exponential distribution, this provides a test for the new-better-than-used-in-expectation and for the new-worse-than-used-in-expectation properties. Such a test is particularly useful in reliability applications, as well as duration and income distribution analysis. The theoretical properties of the testing procedure are established first for uncensored data, and then for censored and truncated data. Simulation studies reveal that the test based on a bootstrap procedure performs well, even with moderate sample sizes. Applications to real data (chief executive officer compensation data, flight delay data, and throttle failure data) illustrate its empirical relevance.
Broad Na D emission in QSOs and the profile of He I 5876 A

For six QSOs, the H-alpha profile was fit to the position of He I 5876 A and Na I 5890, 5896 doublet. The implied Na I/H-alpha ratio ranged between 0.004 and 0.042. Photoionization models were run with a variety of parameters, including density, column density, ionization parameter, two different incident spectra, and either constant density or constant gas pressure. The models use zone results from Ferland's code Cloudy and solved for the sodium emission. The set of cloud parameters that can produce approximately the observed Na I/H-alpha ratios consist of only the high-density clouds, with n(H) about 10 to the 11th/cu cm and only at column densities N(H) = 10 exp 23.5/sq cm or more. The highest Na I/H-alpha ratios are found in models where the sodium is shielded. The large range of observed Na I/H-alpha ratios implies a corresponding range of cloud conditions. 23 refs.
A numerical study of the spectral gap

We present a numerical study of the spectral gap of the Dirichlet Laplacian, γ(K) = λ2(K) − λ1(K), of a planar convex region K. Besides providing supporting numerical evidence for the long-standing gap conjecture that γ(K) ⩾ 3π2/d2(K), where d(K) denotes the diameter of K, our study suggests new types of bounds and several conjectures regarding the dependence of the gap not only on the diameter, but also on the perimeter and the area. One of these conjectures is a stronger version of the gap conjecture mentioned above. A similar study is carried out for the quotient of the first two Dirichlet eigenvalues.
Data‐Driven Bandwidth Selection in Local Polynomial Fitting: Variable Bandwidth and Spatial Adaptation

When estimating a mean regression function and its derivatives, locally weighted least squares regression has proven to be a very attractive technique. The present paper focuses on the important issue of how to select the smoothing parameter or bandwidth. In the case of estimating curves with a complicated structure, a variable bandwidth is desirable. Furthermore, the bandwidth should be indicated by the data themselves. Recent developments in nonparametric smoothing techniques inspired us to propose such a data-driven bandwidth selection procedure, which can be used to select both constant and variable bandwidths. The idea is based on a residual squares criterion along with a good approximation of the bias and variance of the estimator. The procedure can be applied to select bandwidths not only for estimating the regression curve but also for estimating its derivatives. The resulting estimation procedure has the necessary flexibility for capturing complicated shapes of curves. This is illustrated via a large variety of testing examples, including examples with a large spatial variability. The results are also compared with wavelet thresholding techniques, and it seems that our results are at least comparable, i.e. local polynomial regression using our data-driven variable bandwidth has spatial adaptation properties that are similar to wavelets.
INVERSE PROBLEMS IN H, CONTROL THEORY AND LINEAR-QUADRATIC DIFFERENTIAL GAMES

Inverse problems in the settings of H, control theory and linear-quadratic diffrential games are considered. For a given state-feedback control law, necessary (frequency domain) conditions are given in order that the given statefeebdack is the central solution to a standard H, control problem. These conditions together with some additional conditions turn out to be sufficient as well. These conditions appear to be the natural extensions of the corresponding results on the inverse problem of LQ optimal control and admit an interesting graphical interpretation. Similar results are obtained for an analogous inverse problem in the theory of linear-quadratic differential games.
Berry phase in nonlinear systems

The Berry phase acquired by an eigenstate that experienced a nonlinear adiabatic evolution is investigated thoroughly. The circuit integral of the Berry connection of the instantaneous eigenstate cannot account for the adiabatic geometric phase, while the Bogoliubov excitations around the eigenstates are found to be accumulated during the nonlinear adiabatic evolution and contribute a finite phase of geometric nature. A two-mode model is used to illustrate our theory. Our theory is applicable to Bose-Einstein condensate, nonlinear light propagation, and Ginzburg-Landau equations for complex order parameters in condensed-matter physics.
Fluid structure interaction in flexible vessels

The thesis is concerned with the study of fluid-structure interaction in flexible tubes both from the modelling as well as the experimental point of view. More specifically, it presents the first stage of development and testing of a novel unified solution method suitable for fluid-structure interaction problems. In the conventional approach for modelling such problems, the fluid and solid components are treated separately, information is exchanged at their interface and different solution algorithms are used for the two components. The equations for solids are solved for displacement and stress and, the ones for fluids are solved for velocity and pressure. The exchange of information between two solution methods that solve for different quantities is not a trivial task and has also known drawbacks such as high computational cost and potential numerical instabilities, especially for very flexible structures. In the new method presented in the thesis, a single set of equations is used to describe both fluid and solid, while the interface between them is contained within the solution domain itself. This is achieved by reformulating the solid equations to contain the same primitive variables used in fluids i.e. velocity and pressure. The PISO algorithm is used to handle the velocity-pressure coupling. The method proposed is fully tested for solids on a structural dynamic problem (beam bending) and the results compared successfully with the classical structural analysis. In order to quantify the dissipation characteristics of the numerical integration technique, a stability eigenvalue analysis of the proposed time marching and spatial discretisation scheme is performed in one dimension but the conclusions of this analysis were also in agreement with the results of the beam bending. The new formulation for solids is found to be stable and robust, thus it can be used in the next stage of testing in full fluid-structure-interaction problems. The new algorithm can be validated against the results obtained during the experimental phase of the work, which is focused on wave propagation in flexible vessels. This experimental study is also motivated by the need to understand arterial blood flow. Although the general principles governing the arterial hemodynamics are well known, the assessment of non-linearities arising from wall thickness variation and geometric tapering, naturally present in the arterial tree morphology, have not been fully investigated. To this end, a complete experimental data set on wave propagation was collected for six flexible tubes with different wall thickness and geometric tapering.