Miracle-dz/UniFAR-FTUs huggingface dataset:
Optimizing properties of an inertial dynamical system with geometric damping : link with proximal methods

The second-order dynamical system i + ax+ (3\7 2 (x)i: + \i'( :c) = 0, a> 0, (3 > 0, where the Hessian \7 2 ( x) acts as a geometric damping, is introduced, mainly in view of the rninirniz:ation of . Miuiruiz:ing is a problem equivalent to the minimization of the functional Wa,b(x,y) = p(x) + ~Jax + byj 2 , a > 0, b > 0. The latter naturally appears in the proximal regula­ riz:ation of ; it may also Le vi ewed as an energy. The continuous steepest descent method appli ed to \II a,b yields a first-order system, which proves to Lc equivalent to the above-mentioned second-order system, when is of class C 2 0
Status of Higgs boson searches at the beginning of the LHC era

In recent years the Tevatron Run-II collaborations have extended the search for Higgs bosons which was pioneered during the LEP accelerator operation between 1989 and 2000. This review concisely discusses the experimental constraints set by the CDF and DO collaborations with the complete dataset taken up to September 2011. Model-independent and model-dependent limits on Higgs boson masses and couplings have been set and interpretations are discussed both in the context of the Standard Model and in extended models. In spring 2012 the Tevatron extended the excluded SM Higgs boson mass range to 147 < mH < 179 GeV at 95% CL in the high-mass region beyond the LEP limit. The summer 2012 results for the same dataset pushed the expected limit from 141 GeV down to 139 GeV, while the observed limits remained unchanged. In the low-mass region an excess of data events with respect to the background estimation is observed in the mass range 120 < mH < 135 GeV which causes the limits to be not as stringent as expected. The significance for such an excess anywhere in the full mass range is approximately 2. 5σ. Focusing on the associated production of a Higgs boson with a W or Z boson and the subsequent decay of the Higgs boson to a bottom–antibottom quark pair, evidence for the presence of a new particle, consistent with the SM Higgs boson has been established, with the largest local significance of 3. 3σ, corresponding to a global significance of 3. 1σ. The Tevatron observation in the given mass range is consistent with the discovery of a new particle of about 125 GeV mass at the LHC. The sensitivity increase in recent years is illustrated owing to the increase in data available and improvements in analysis. The achieved experimental sensitivities are also compared to the previous predictions.
Collapse and fragmentation of isothermal and polytropic cylindrical clouds

Two-dimensional hydrodynamic calculations were performed to study the collapse and fragmentation of initially uniform, nonrotating axisymmetric clouds with isothermal and polytropic equations of state for various ratios of length to diameter L/D and values of the polytropic index gamma. The outcome of the collapse depends on the initial Jeans number of the cloud J(0) (ratio of gravitational to thermal energies): if J(0) is smaller than J(c), the cloud rebounds, so it is not gravitationally bound, and if J(0) is greater than J(c), it collapses irreversibly. A simple linear relation is found between the values of the critical Jeans numbers J(c) for a given gamma and their corresponding values in the isothermal case, indicating that the effects of pressure on the outcome of the collapse are independent of cloud geometry. For sufficiently high values of J(0), the cloud forms two fragments along the axis of the cylinder. Values of J(2-frag), the minimum J(0) for which these fragments survive, conjectured by Bastien (1983), are determined numerically. It is suggested that the fragmentation of elongated clouds with L/D is greater than 1.7 and J(0) is greater than J(2-frag) is an important way of forming binary stars which are difficult to form otherwise. 30more » refs.« less
Magnetic Anisotropies and Exchange Bias of Co/CoO Multilayers with Intermediate Ultrathin Pt Layers

Co/CoO multilayers are fabricated by means of radio-frequency magnetron sputtering. For the formation of each multilayer period, a Co layer is initially produced followed by natural oxidation. Platinum is used not only as buffer and capping layers, but also in the form of intermediate ultrathin layers to enhance perpendicular magnetic anisotropy. Three samples are compared with respect to the magnetic anisotropies and exchange bias between 4–300 K based on superconducting quantum interference device magnetometry measurements. Two of the multilayers are identical Co/CoO/Pt ones; one of them, however, is grown on a Co/Pt “magnetic substrate” to induce perpendicular magnetic anisotropy via exchange coupling through an ultrathin Pt intermediate layer. The third multilayer is of the form Co/CoO/Co/Pt. The use of a “magnetic substrate” results in the observation of loops with large remanence when the field applies perpendicular to the film plane. The CoO/Co interfaces lead to a significant exchange bias at low temperatures after field cooling. The largest exchange bias was observed in the film with double Co/CoO/Co interfaces. Consequently, significant perpendicular anisotropy coexists with large exchange bias, especially at low temperatures. Such samples can be potentially useful for applications related to spintronics and magnetic storage.
Parallel computation of multiscale phenomena in magnetically‐stirred solidifying melts

Purpose – The aim of this paper is to determine a parallel computational methodology for simultaneously predicting the macro/micro scale phenomena occurring during solidification processing with external electromagnetic stirring.Design/methodology/approach – Macro and micro phenomena occurring in an electromagnetically‐stirred solidifying melt are simulated using a numerical model that integrates the finite element methodology for transport phenomena and the Monte‐Carlo cellular‐automata method for microstructure formation. Parallel algorithm is introduced to enhance the computational efficiency.Findings – Computed results show that parallel algorithm can be effective in enhancing the computational efficiency of a combined macro/micro model if it is applied appropriately. Also, electromagnetically induced stirring can have a strong effect on the nucleation and grain growth and hence the final solidification microstructure.Originality/value – This paper fulfils a need for developing an efficient numerical .
Comparative evaluation of absorbing boundary conditions using Green's functions for layered media

Absorbing boundary conditions are comparatively studied using the Green's functions of the vector and scalar potentials for multilayer geometries and general sources. The absorbing boundaries are introduced as additional layers with predefined reflection coefficients into the calculation of the Green's functions. The Green's functions are calculated using different reflection coefficients corresponding to different absorbing boundaries and compared to those obtained with no absorbing boundary. This approach provides an absolute measure of the effectiveness of different absorbing boundaries.
THE ANALYSIS OF REPEATED MEASUREMENTS : UNIVARIATE TESTS, MULTIVARIATE TESTS, OR BOTH ?

One strategy which has been recommended for examining effects in repeated measures designs combines a degrees of freedom (d.f.)-adjusted univariate F test and a multivariate test. The results of a simulation study for a groups × trials repeated measures design are presented, and demonstrate that for balanced designs this combined strategy rarely provided superior Type I error control to that afforded by uniformly adopting either a univariate or multivariate test. For unbalanced repeated measures designs, all three strategies typically resulted in very conservative or very liberal Type I error rates when covariance matrices and group sizes were positively and negatively paired, respectively. For such designs, the approximate d.f. Welch-James (James, 1951, 1954; Welch, 1947, 1951) multivariate statistic developed by Johansen (1980) is preferable to any of the other strategies investigated in this paper. Power comparisons also favour the use of the Welch-James test.
Comparison of hollow cone and axial bright field electron microscope imaging techniques

The use of hollow cone illumination in improving the contrast transfer in bright field high resolution electron micrographs is investigated experimentally. Analysis of the results on an optical bench indicates that, although the contrast transfer is free of sign reversals, the contrast is reduced by a factor of up to 3ṁ3 in relation to axial bright field imaging. This constitutes a severe limitation to the usefulness of the hollow cone bright field technique, particularly in situations where the signal to noise level is already poor, as in high resolution imaging of non‐crystalline specimens. Factors governing the contrast in hollow cone illumination are discussed.
Solution of Hybrid FEM-BEM Systems via Schur Complement Techniques

We are concerned with the numerical solution linear systems that arise from a hybridization of the Finite Element Method (FEM) and the Boundary Element Method (BEM). Our present focus is hybrid FEM-BEM discretization of the frequency-domain vector Helmholtz equation of electromagnetics, but similar hybrid techniques are used in electrostatics, acoustics, elasticity, etc. The hybrid FEM-BEM technique is used to solve ''open'' or ''infinite'' problems, where the FEM is used to discretize the interior of the problem and the BEM is used to simulate the effect of the infinite domain. This is illustrated generically in two dimensions in Figure 1 below. The FEM is applied to the interior V, the BEM is applied to the fictitious surface S, and the two methods are appropriately coupled to form a well-posed problem.
Inverse cascade in the structure of substorm aurora and non-linear dynamics of field-aligned current filaments

Abstract. We investigate time evolution of scaling index αA that characterizes auroral luminosity fluctuations at the beginning of substorm expansion. With the use of UVI images from the Polar satellite, it is shown that αA typically varies from values less than unity to ~1.5, increasing with breakup progress. Similar scaling features were previously reported for fluctuations at smaller scales from all-sky TV observations. If this signature is interpreted in terms of non-linear interactions between scales, it means that the power of small-scale fluctuations is transferred with time to larger scales, a kind of the inverse cascade. Scaling behavior in the aurora during substorm activity is compared with that in the field-aligned currents simulated numerically in the model of non-linear interactions of Alfvenic coherent structures, according to the Chang et al. (2004) scenario. This scenario also suggests an inverse cascade, manifesting in clustering of small-scale field-aligned current filaments of the same polarity and formation of "coarse-grained" structures of field-aligned currents.
1/f noise in linearized low resistance MgO magnetic tunnel junctions

Low RA MgO magnetic tunnel junctions prepared at Singulus (Ta3∕CuN30∕Ta5∕PtMn20∕CoFe2.5∕Ru0.7∕CoFeB3∕MgO1.2∕CoFeB3∕Ta5 (thickness in nanometers) were microfabricated at INESC-MN. The junctions were patterned into micron-sized sensors (5–20μm2) with controlled shape anisotropy (aspect ratio ranging from 2 to 20). A small external longitudinal bias field (15–30 Oe) was further used to improve sensor linearity. The MgO junctions have a resistance-area product of 150Ωμm2 and a maximum tunnel magnetoresistance of 130%. Noise measurements were done in linearized sensors, from dc to 500 kHz. The magnetic and nonmagnetic contributions to the 1∕f noise were determined. From the data fitting, Hooge parameters of ∼2.20×10−9μm2 were obtained for the nonmagnetic 1∕f noise. Analysis of direct experimental data revealed the possibility to detect variations of magnetic fields in the order of 10−10T∕Hz0.5 with these MgO junctions, demonstrating their potential for ultralow-field detection.
Symmetrical transformation of basic translation vectors in the supercell model of imperfect crystals and in the theory of special points of the Brillouin zone

The matrices of the symmetrical transformations for all the three-dimensional Bravais lattices are found. These matrices may be applied for the investigation of physical properties of single defects in crystals in the supercell model. The corresponding transformations of reciprocal lattices with a not more than 32-fold decrease of the Brillouin zone volume are used for the generation of special point sets for the approximative numerical integration over the Brillouin zone in cubic crystals with simple, face-centred and body-centred lattices.
Determining changes in definition of conformation traits and the effect on international evaluations

Conformation traits in dairy cattle are scored in a subjective way. A classifier scores an animal following a certain definition for a trait. These definitions are set by a herdbook organisation or in Holstein cattle, by the World Holstein Friesian Federation (WHFF). Within the conformation traits two groups can be distinguished: linear traits and general characteristics. A linear trait is scored on a linear scale, where traits are scored individually from one biological extreme to the other. The variation within traits is identifiable and no direction for a certain desirability is given. With the linear scoring system a dairy cow is described for the most important conformation traits. At this moment WHFF has defined 16 standard traits, which should be score by all members of WHFF identically. The general characteristics, or breakdowns, give a linear qualification and characteristic of the cow in relation to the standard, and are not linear in a biological sense.
Impact jetting by a solid sphere

We use a novel ultra-high-speed video camera to study the initial stage of the impact of a solid sphere onto a liquid surface, finding a high-speed horizontal jet which emerges immediately following the intial contact. For ${\hbox{\it Re}} > 2 \times 10^4$ the jet emerges when the horizontal contact between the sphere and the liquid is only 12% of its diameter. For the largest Reynolds numbers this jet can travel at more than 30 times the impact velocity of the sphere. This jetting occurs sooner and at much higher normalized velocities than has been observed previously. The breakup of the jet into a spray of droplets sometimes occurs through formation of pockets in the liquid sheet. Early in the impact, the energy transferred to the jet and the subsequent spray sheet is estimated to be much larger than the energy associated with the added mass inside the liquid pool. The jetting will therefore greatly increase the initial impact force on the sphere.
Complexity results for infinite-horizon markov decision processes

Markov decision processes (MDPs) are models of dynamic decision making under uncertainty. These models arise in diverse applications and have been developed extensively in fields such as operations research, control engineering, and the decision sciences in general. Recent research, especially in artificial intelligence, has highlighted the significance of studying the computational properties of MDP problems. We address computational complexity questions in solving MDP problems under infinite-horizon optimization criteria. In an infinite-horizon or an indefinite-horizon criterion, we are interested in making good decisions for the long run or an indefinite period of time. A distinction that partitions the thesis is the assumption on the observability of the state of the system with which the decision maker interacts. In the first half of the thesis, we focus on partially observable or POMDP problems, wherein there is uncertainty about the current state of the system at times of decision. We show that many POMDP problems are undecidable. We make use of an undecidability result in research on probabilistic finite automata to establish our results. analyze these algorithms on restricted classes of problems, including deterministic MDPs and MDPs whose linear programming formulations take two variables per inequality, and establish that several algorithms based on value or policy iteration are polynomial. Tools of analysis include studying parametric versions of the problems and viewing policy iteration as a Newton's method for finding the zero of a function. We expect that extending the analysis of policy iteration as a Newton's method will establish policy iteration to be polynomial on general fully observable MDPs.
M-plane GaN grown on m-sapphire by metalorganic vapor phase epitaxy

GaN layers have been grown on m-plane sapphire by metal organic vapor phase epitaxy using low-temperature AlN nucleation layers. Depending on substrate nitridation and annealing treatments prior to depositing the nucleation layer, the crystal orientation of the resulting GaN layer may be either (11−22) or (1−100) (m plane). For suitably controlled conditions, GaN epilayers with a single m-plane orientation are reproducibly obtained as confirmed by x-ray diffraction. There is a 90° in-plane rotation of the epilayer such that the GaN a axis is parallel to the sapphire c axis.
Effect of femtosecond laser radiation on morphofunctional state of neoplasm in vitro

The effect of femtosecond laser radiation provided by the Erbium fiber laser with the pulse duration of 10-13 s, peak and average power of 6,0±0,3 kW and 1,26±0,15 mW, respectively, wavelength λ of 1,55 μm has been studied in the experiments on rat ascitic ovarian tumor cell in vitro. Irradiation has been performed at the average intensity of 0,033±0.002 mW/cm2 at two expositions under femtosecond laser radiation of 600 and 900 s. The membrane topology and rigidity of the cancer cells have been estimated with the Scanning probe microscopy (SolverPro, NT-MDT, Russia). Besides, the viability and apoptosis of the cancer cells have been estimated. Free-radical processes and antioxidant enzyme activity have been studied in cancer cell lysate. Femtosecond laser irradiation was established to increases the activity of the "Lipoperoxidation - antioxidants" system in neoplasm, enhance the apoptosis, decrease the viability, and change cancer cell membrane topology and rigidity in vitro depending on the energy density of the irradiation.
MAGNETIC FORCE BETWEEN INCLINED CIRCULAR LOOPS (LORENTZ APPROACH)

This paper presents a new general formula for calculating the magnetic force between inclined circular loops placed in any desired position. This formula has been derived from the Lorentz force equation. All mathematical procedures are completely described to deflne the coil positions that lead to a relatively easy method for calculating the magnetic force between inclined circular loops in any desired position. The presented method is easy to understand, numerically suitable and easily applicable for engineers and physicists. The obtained formula is given in its simplest form from the already existing formulas for calculating the magnetic force between inclined circular loops. We validated the new formula through a series of examples, which are presented here.
The Poisson–exponential distribution: a Bayesian approach

In this paper, we proposed a new two-parameter lifetime distribution with increasing failure rate. The new distribution arises on a latent complementary risk scenario. The properties of the proposed distribution are discussed, including a formal proof of its density function and an explicit algebraic formulae for its quantiles and survival and hazard functions. Also, we have discussed inference aspects of the model proposed via Bayesian inference by using Markov chain Monte Carlo simulation. A simulation study investigates the frequentist properties of the proposed estimators obtained under the assumptions of non-informative priors. Further, some discussions on models selection criteria are given. The developed methodology is illustrated on a real data set.
Using optical fibre cavities to create multi-atom entanglement by quantum zeno dynamics

In this thesis, we show how an optical microcavity setup can create multiparticle entanglement in an ensemble of neutral atoms by means of quantum Zeno dynamics (QZD). Our setup combines an atom chip with a fibre Fabry-Perot (FFP) resonator and allows us to load an ensemble of Rb87 atoms into a single node of an intracavity dipole trap, coupling the atoms strongly and identically to the cavity light field which enables us to perform a quantum non-destructive measurement of their collective state.We realise QZD by modifying the dynamics of the collective state (encoded in atomic hyperfine states addressed with MW radiation) by means of frequent cavity measurements at optical frequency. This QZD is shown to create multiparticle entanglement in a fast and deterministic scheme. To analyse the created states, we reconstruct the symmetric part of the atomic density matrix from 2d measurements of the ensemble's Husimi Q-distribution. We give a time-resolved account of the creation of states with at least 3-11 entangled atoms and fidelity of up to 0.37 with respect to a W state of 36 atoms. Studying the influence of measurement strength and experimental imperfections, we show that our experiments are well described by simple models with no free parameters.This thesis also presents work towards improved FFP cavities. We discuss the problem of frequency splitting of polarisation eigenmodes in cavities made from two fibres microfabricated with a CO2 laser. We show that this effect depends on the symmetry of the microfabricated structures and demonstrate that it can be controlled both at the level of fabrication and when assembling a cavity.
Nonlinear output stabilization control for multimachine power systems

In this paper, a robust decentralized nonlinear control scheme is proposed for multimachine power system stability enhancement. The nonlinear controller consists of a novel dynamic direct feedback linearization (DFL) compensator through the excitation loop to cancel the nonlinearities and interactions among generators and a robust feedback controller to guarantee the asymptotic stability of the DFL compensated system considering the effects of dynamic output feedback and plant parametric uncertainties. The decentralized controller for each generator in the multimachine system is obtained by solving an algebraic Riccati equation. The nonlinear controller can guarantee the stability of the multimachine nonlinear power system within a whole operating region for all admissible parameters. The design procedure is tested on a three-machine power system. Simulation results show that the proposed control scheme can greatly enhance the stability of the system, regardless of the network parameters, operating points, and fault locations.
Antiferromagnetic anisotropic XXZ chain of spins S= 1/2 in the presence of an inhomogeneous transverse magnetic field as a basis for the multiqubit quantum register simulation

This article presents the results of studies of the linear antiferromagnetic spin chain with uniaxial anisotropy (XXZ– model) placed in a transverse magnetic field directed along the anisotropy axis of the chain with a constant gradient along the chain. A spin Hamiltonian for the states close to the ground was written in the spin-wave approximation. It was diagonalized by an asymptotic expansion in the small parameter describing the magnitude of the field gradient. Local energy of the ground state and the reduced density matrix of the quantum states for a selected pair of spins in the chain have been considered in the gapped and gapless cases. Local spin polarization and the local toroidal magnetic moment have also been found. Local pair entanglement of quantum states as a characteristic of quantum correlations in the spin chain was studied.