Miracle-dz/UniFAR-FTUs huggingface dataset:
Algorithms for Efficient Computation of Transfer Functions for Large Order Flexible Systems

An efficient and robust computational scheme is given for the calculation of the frequency response function of a large order, flexible system implemented with a linear, time invariant control system. Advantage is taken of the highly structured sparsity of the system matrix of the plant based on a model of the structure using normal mode coordinates. The computational time per frequency point of the new computational scheme is a linear function of system size, a significant improvement over traditional, full-matrix techniques whose computational times per frequency point range from quadratic to cubic functions of system size. This permits the practical frequency domain analysis of systems of much larger order than by traditional, full-matrix techniques. Formulations are given for both open- and closed-loop systems. Numerical examples are presented showing the advantages of the present formulation over traditional approaches, both in speed and in accuracy. Using a model with 703 structural modes, the present method was up to two orders of magnitude faster than a traditional method. The present method generally showed good to excellent accuracy throughout the range of test frequencies, while traditional methods gave adequate accuracy for lower frequencies, but generally deteriorated in performance at higher frequencies with worst case errors being many orders of magnitude times the correct values.
Current filamentation and onset in magnetoplasmadynamic thrusters

The possible role of current filamentation in the operation of magnetoplasmadynamic thrusters is investigated here by means of a stability analysis of a current-carrying plasma in a simplified coaxial configuration. Magnetoplasmadynamic thrusters are known to enter a strongly unstable regime, named onset in the literature, when operated above a threshold current level, given the propellant mass flow rate. During onset, a transition from diffuse to spotty current pattern occurs, leading to intense fluctuations of thruster terminal voltage and to severe anode damage with commonly employed anode materials. Despite several experimental and theoretical efforts in the last few decades, no complete and definitive understanding of the physical nature of this phenomenon is yet available. In this work it is shown that conditions suitable for azimuthal symmetry breaking and the subsequent development of this instability can actually exist in magnetoplasmadynamic thrusters. A physically coherent explanation of the complex onset phenomenology is then proposed, showing that both the plasma dynamics and the voltage fluctuations can be ultimately explained in terms of the filamentation instability and its effects.
Spectroscopy of polycyclic aromatic hydrocarbons and very small grains in photodissociation regions

We have coupled a singular value decomposition method with a Monte Carlo search algorithm to analyse the mid-infrared ISOCAM spectral maps of photodissociation regions (PDRs) in NGC 7023 and ρ Oph-SR3.Three different spectra and their associated spatial distribution were extracted from this analysis. It is shown that they can be associated with polycyclic aromatic hydrocarbons (PAHs) in their cationic and neutral forms and a third population of carbonaceous very small grains (VSGs). The method allows for the first time (i) to separate the contribution of neutral PAHs to the interstellar emission spectrum from that of cationic PAHs; (ii) to show that the 7.8 μ m component of the “7.7 μ m” broad feature is carried by VSGs, whereas the 7.6 μ m component is due to PAHs; and (iii) to give evidence that free-flying PAHs are produced in PDRs by photoevaporation of VSGs. It is proposed that these carbonaceous VSGs are indeed PAH clusters. We derived a minimal size of 400 carbon atoms per cluster and estimated a UV absorption power of the order of 10 -24 W C -1 for their dissociation.
Trade-Off Relationship between Si Recess and Defect Density Formed by Plasma-Induced Damage in Planar Metal–Oxide–Semiconductor Field-Effect Transistors and the Optimization Methodology

Physical damage induced by high-energy ion bombardment during plasma processing is characterized from the viewpoint of the relationship between surface-damaged layer (silicon loss) and defect site underneath the surface. Parameters for plasma-induced damage (PID), Si recess depth (dR) and residual (areal) defect density after wet-etch treatment (Ndam), are calculated on the basis of a modified range theory, and the trade-off relationship between dR and Ndam is presented. We also model their effects on device parameters such as off-state leakage (Ioff) and drain saturation current (Ion) of n-channel metal–oxide–semiconductor field effect transistors (MOSFETs). Based on the models, we clarify the relationship among plasma process parameters (ion energy and ion flux), dR, Ndam, Ioff, and Ion. Then we propose a methodology optimizing ion energy and ion flux under the constraints defined by device specifications Ioff and Ion, via dR and Ndam. This procedure is regarded as so-called optimization problems. The proposed methodology is applicable to optimizing plasma parameters that minimize degradation of MOSFET performance by PID.
Proposal of Design Criteria for Gas Entrainment from Vortex Dimples Based on a Computational Fluid Dynamics Method

Design criteria for gas entrainments (GE) from the liquid surface in a fast breeder reactor system were proposed in this paper for the two types of GE phenomena from a vortex dimple based on a computational fluid dynamics (CFD) method. The first gas entrainment phenomenon is a gas core extension directly to the outlet piping level, which induces large amount of GE to the flow system. The second is continuous bubble detachments from the tip of the vortex dimple. Based on CFD calculations for elemental experiments of the surface vortex, local CFD non-dimensional numbers were defined as the design criteria to prevent GE. In conclusion, it was found that the CFD non-dimensional numbers are useful for the design parameters of GE prevention.
Absorption properties and evolution of active galactic nuclei

Context. Aims. Intrinsic absorption is a fundamental physical property to understand the evolution of active galactic nuclei (AGN). Here a sample of 1290 AGN, selected in the 2‐10 keV band from dierent flux-limited surveys with very high optical identification completeness is studied. Methods. The AGN are grouped into two classes, unabsorbed (type-1) and absorbed (type-2), depending on their optical spectroscopic classification and X‐ray absorption properties, using hardness ratios. Utilizing the optical to X‐ray flux ratios, a rough correction for the 8% redshift incompleteness still present in the sample is applied. Then the fraction of absorbed sources is determined as a function of X-ray luminosity and redshift. Results. A strong decrease of the absorbed fraction with X-ray luminosity is found. This can be represented by an almost linear decrease from 80% to 20% in the luminosity range logLX=42‐46 and is consistent with similar derivations in the optical and MIR bands. Several methods are used to study a possible evolution of the absorption fraction. A significant increase of the absorbed fraction with redshift is found, which can be described by a power law (1+ z) 0:760:12 , saturating at a redshift of z2. Conclusions. The variation of the AGN absorption with luminosity and redshift is described with higher statistical accuracy and smaller systematic errors than previous results. The findings have important consequences for the broader context of AGN and galaxy co-evolution. Here it is proposed that the cosmic downsizing in the AGN population is due to two dierent feeding mechanisms: a fast process of merger driven accretion at high luminosities and high redshifts versus a slow process of gas accretion from gravitational instabilities in galactic disks rebuilding around pre-formed bulges and black holes.
A new algorithm for selecting equip system based on fuzzy operations

In this endeavor, the authors discuss the problem of defuzzification based on parametric interval approximation of fuzzy numbers and then suggest measure about these points of fuzzy numbers. The measure point of each fuzzy number plays an important role in fuzzy sets and systems, specifically in physics, mathematics and statistics. We provide the definition of the measure of fuzzy numbers as well as the definition of measures in probability theory. Some of their applications are mentioned.
A spectral slope versus perihelion distance correlation for planet-crossing asteroids

The spectral slope of sunlight reflected by an asteroid surface may change with time as a result of several physical processes acting on the surface layer known as ‘space weathering’. The effects of space weathering are important for asteroid studies because they may help us to explain the paucity of spectroscopic analogues of ordinary chondrites (OCs) among the main belt asteroids. In this Letter we report a new result that may be used to understand better how asteroid surfaces evolve with time. Using a large data set of spectroscopic observations of planet-crossing asteroids (near-Earth objects and Mars-crossers), we have found a statistically significant correlation between their spectral slope and the perihelion distance. We have also determined that the Q- and Sq-type planet-crossing asteroids are more abundant (relative to more space-weathered S-type asteroids) at small perihelion distances that characterize dynamically evolved orbits. We take these results as evidence for some (so far neglected) process that modifies surfaces of planet-crossing asteroids. As originally proposed by Nesvorný et al., the close encounters of these objects with the terrestrial planets may produce tidal perturbations to their surfaces that may partially, or even completely, remove the old and weathered layers and expose non-weathered OC-like material. Our findings may provide new evidence for this process because standard models for the dynamical evolution of asteroids show that planet-crossing asteroids with small perihelion distances have undergone more frequent planetary encounters than those residing in more distant orbits. Therefore, if planetary encounters are important, the distribution of Q-type asteroids in the planet-crossing space should show a correlation with the perihelion distance, exactly as we have found here.
Magnetosphere cyclotron maser: Backward wave oscillator generation regime

A new generation regime of the magnetosphere cyclotron maser is considered, based on phase coherence effects in wave-particle systems with step-like deformations of electron velocity distribution functions. Such deformations appear during cyclotron interactions of noise-like whistler wave emissions and energetic electrons at the boundaries between resonant and nonresonant particles. The new regime is similar to the backward wave oscillator in laboratory electronic devices. This regime applies to the generation of chorus emissions and may explain the connection between chorus and hiss, their fast growth rates, and the temporal succession of chorus elements.
Luminescence associated with the presence of dislocations in silicon

A brief account is given of some recent investigations of the luminescence associated with the presence of dislocations in silicon. These investigations show that transition metal contamination is necessary for dislocation related luminescence to be observed in plastically-deformed float-zone silicon and in material containing epitaxial and oxidation-induced stacking faults. Cathodoluminescence spectroscopy and imaging measurements, and photoluminescence measurements on material with low densities of grown-in dislocations, imply that the D3 and D4 luminescence features originate in the dislocation cores, whereas the D1 and D2 features are associated with point defects trapped in the strain fields of dislocations.
Interparticle interactions and the switching field distribution of barium ferrite media

A series of barium ferrite disks with a variation in volumetric packing density from 1.5% to 35% were investigated to determine the effect of interparticle interactions on the switching field distribution (SFD) of the media. Kelly et al. (1989) introduced a parameter Delta M(H) to highlight deviations from the theoretical non-interacting assembly. The degree of interparticle interactions were determined from the principal remanence curves and the subsequent calculation of the Delta M(H) parameter. It was found that the SFD of these disks became narrower as the volumetric packing density increased, and that the SFD width strongly correlated with the strength of the interparticle interactions as measured from the Delta M(H) plot. Examination of scanning electron micrographs of these disks revealed that for the low-packing-density disks, separation between the stacks of particles was large and that the separation decreased as the volumetric packing density was increased. It is believed that the properties of the media result not only from the large interparticle interaction arising from particle stacking, but also from the interaction between the stacks. >
Can the Weyl algebra be a fixed ring

If a finite soluble group acts as automorphisms of a domain, then the invariant subring is not isomorphic to the first Weyl algebra C(r, d/dt) . Let R = C(t ,d/dt) be the first Weyl algebra. We prove the following result. Theorem. Let G be a finite solvable group. Let S d R be a C-algebra such that (a) SR and RS are finitely generated, (b) S is a domain, (c) G acts as automorphisms of S, and S = R. Then S = R.
Revisiting single-gated Mixtures of Experts

Mixture of Experts (MoE) are rising in popularity as a means to train extremely large-scale models, yet allowing for a reasonable computational cost at inference time. Recent state-of-the-art approaches usually assume a large number of experts, and require training all experts jointly, which often lead to training instabilities such as the router collapsing In contrast, in this work, we propose to revisit the simple single-gate MoE, which allows for more practical training. Key to our work are (i) a base model branch acting both as an early-exit and an ensembling regularization scheme, (ii) a simple and efficient asynchronous training pipeline without router collapse issues, and finally (iii) a per-sample clustering-based initialization. We show experimentally that the proposed model obtains efficiency-to-accuracy trade-offs comparable with other more complex MoE, and outperforms non-mixture baselines. This showcases the merits of even a simple single-gate MoE, and motivates further exploration in this area.
Neyman type A distribution revisited

The modality structure of the Neyman type A distribution is examined. The results obtained add to those previously stated in Barton (1957) (or in Johnsonet al. (1992, p. 370) ) and in Shenton and Bowman (1967) . Strong unimodality of this distribution is also considered. Problem 328 in Statistica Neerlandica ( Theodorescu (1997) ) and its solution ( Borwein (2000) ) play an important part.
Compact tripotents in bi-dual JB*-triples

Abstract The set consisting of the partially ordered set of tripotents in a JBW*-triple C with a greatest element adjoined forms a complete lattice. This paper is mainly concerned with the situation in which C is the second dual A** of a complex Banach space A and, more particularly, when A is itself a JB*-triple. A subset of consisting of the set of tripotents compact relative to A (denned in Section 4) with a greatest element adjoined is studied. It is shown to be an atomic complete lattice with the properties that the infimum of an arbitrary family of elements of is the same whether taken in or in and that every decreasing net of non-zero elements of has a non-zero infimum. The relationship between the complete lattice and the complete lattice where B is a Banach space such that B** is a weak*-closed subtriple of A** is also investigated. When applied to the special case in which A is a C*-algebra the results provide information about the set of compact partial isometries relative to A and are closely related to those recently obtained by Akemann and Pedersen. In particular it is shown that a partial isometry is compact relative to A if and only if, in their terminology, it belongs locally to A. The main results are applied to this and other examples.
Investigation of trigonal (La1-xNdx)3Ga5SiO14 crystals. II. Spectral laser and electromechanical properties

Absorption, luminescence characteristics, and stimulated emission parameters of Nd3+ ions in the wide temperature region of a full concentration series of (La1−xNdx)3Ga5SiO14 single crystals are studied. Luminescence intensity characteristics are analyzed and transition cross-section at the laser wavelengths of two 4F3/2 4I11/2 and 4F3/2 4I13/2 generation channels of activator are determined. Registered induced transitions are identified. Electromechanical characteristics of La3Ga5SiO14, specifically, elastic, dielectric, and piezoelectric modules and constants are investigated. A comparison of the properties between La3Ga5SiO14 crystals and crystalline SiO2 is carried out. [Russian Text Ignored. ]
THE LARGE-SCALE DISTRIBUTION OF GALAXIES AND CLUSTERS OF GALAXIES

The nonrandom clustering of galaxies and clusters of galaxies has attracted increasing attention in the past 40 years. The mathematical tests and criteria used to distinguish between an observed distribution and a Poisson, i.e., random, statistically uniform distribution, are outlined. The observational evidence for (and against) hierarchical clustering of galaxies and clusters on various characteristic length scales A from 0.1 Mpc to at least 100 Mpc, is reviewed. Some cosmological implications and possible origins of the clustering spectrum are discussed. Key words: galaxies - clusters of galaxies 1. Introduction 2. Subclustering: pairs and multiplets (A 0.1 Mpc) 3. Small-scale clustering: groups and small clusters (A 1 Mpc) 4. Statistical principles 5. Index of dumpiness and dispersion-subdivision curves 6. Correlation techniques and power spectrum analysis 7. Galactic absorption effects A. Average effects B. Fluctuation effects 8. Medium-scale clustering: large clusters, cloud complexes, and superclusters (A 10 Mpc) 9. The distribution of rich clusters A. The Zwicky Catalog B. The Abell Catalog 10.Large-scale clustering and density gradients (A 100 Mpc) 11.Galaxy clustering and the density-radius relation 12.The spectrum of clustering and its origin
Corrections for Temporal Discontinuities in the OPI

Abstract The longest record of precipitation estimated from satellites is the outgoing longwave radiation (OLR) precipitation index (OPI), which is based on polar-orbiting infrared observations from the Advanced Very High Resolution Radiometer (AVHRR) instrument that has flown onboard successive NOAA satellites. A significant barrier to the use of these data in studies of the climate of tropical precipitation (among other things) is the large bias caused by orbital drift that is present in the OLR data. Because the AVHRR instruments are deployed on the polar-orbiting spacecraft, OLR observations are recorded at specific times for each earth location for each day. Discontinuities are caused by the use of multiple satellites with different observing times as well as the orbital drift that occurs throughout the lifetime of each satellite. A regression-based correction is proposed based solely on the equator crossing time (ECT). The correction allows for separate means for each satellite as well as separate c.
An efficient frequency domain state-space identification algorithm: robustness and stochastic analysis

In this paper we present and analyze a novel algorithm for identifying linear time-invariant discrete time state-space models from frequency response data. The algorithm is noniterative and exactly recovers a true system of order n, if n+2 noise-free uniformly spaced frequency response measurements are given. Analysis show that if the measurements are perturbed with errors upper bounded by /spl epsiv/ the identification error will be upper bounded by /spl epsiv/ and hence the algorithm is robust. An asymptotic stochastic analysis show, under weak assumptions, that the algorithm is consistent if the measurements are contaminated with noise. <<ETX>>
Instabilities during batch sedimentation in geometries containing obstacles: A numerical and experimental study

Batch sedimentation of non‐colloidal particle suspensions is studied with nuclear magnetic resonance flow visualization and continuum‐level numerical modelling of particle migration. The experimental method gives particle volume fraction as a function of time and position, which then provides validation data for the numerical model. A finite element method is used to discretize the equations of motion, including an evolution equation for the particle volume fraction and a generalized Newtonian viscosity dependent on local particle concentration. The diffusive‐flux equation is based on the Phillips model (Phys. Fluids A 1992; 4:30–40) and includes sedimentation terms described by Zhang and Acrivos (Int. J. Multiphase Flow 1994; 20:579–591). The model and experiments are utilized in three distinct geometries with particles that are heavier and lighter than the suspending fluid, depending on the experiment: (1) sedimentation in a cylinder with a contraction; (2) particle flotation in a horizontal cylinder with a horizontal rod; and (3) flotation around a rectangular inclusion. Secondary flows appear in both the experiments and the simulations when a region of higher density fluid is above a lower density fluid. The secondary flows result in particle inhomogeneities, Rayleigh–Taylor‐like instabilities, and remixing, though the effect in the simulations is more pronounced than in the experiments. Published in 2007 by John Wiley & Sons, Ltd.
Energy position of near-band-edge emission spectra of InN epitaxial layers with different doping levels

We studied the shape and energy position of near-band-edge photoluminescence spectra of InN epitaxial layers with different doping levels. We found that the experimental spectra of InN layers with moderate doping level can be nicely interpreted in the frames of the "free-to-bound" recombination model in degenerate semiconductors. For carrier concentrations above n>5x10(18) cm(-3) the emission spectra can also be modeled satisfactorily, but a contribution due to a pushing up of nonequilibrium holes over the thermal delocalization level in the valence band tails should be considered in the model. The emission spectra of samples with low doping level were instead explained as a recombination from the bottom of the conduction band to a shallow acceptor assuming the same value of the acceptor binding energy estimated from the spectra of highly doped samples. Analyzing the shape and energy position of the free-electron recombination spectra we determined the carrier concentrations responsible for the emissions and found that the fundamental band gap energy of InN is E-g=692+/-2 meV for an effective mass at the conduction-band minimum m(n0)=0.042m(0).