Miracle-dz/UniFAR-FTUs huggingface dataset:
Word Similarity Algorithm Based on WordNet And HowNet

To make the word similarity calculated results more reasonable and accurate, a new word similarity algorithm is proposed. It uses HowNet primitive hierarchical tree structure, and calculates the two primitives’ distance with the method computing WordNet node distance which considers the tree depth, density, path and connecting intensity, etc. Moreover, algorithm also improves the method that distance into similarity. Finally, this algorithm is compared with related algorithms through experiment. The results show that the proposed algorithm effectively improves the precision and accuracy of word similarity calculation.
Laboratory astrophysics using high energy lasers: need for 2D simulation

A certain number of experiments have been performed and planned for the future aiming to reproduce in a laboratory common astrophysical situations [1]. Among those, astrophysical jets have been the subject of elaborate studies in both theory [2] and observations [3]. Nevertheless, they still raise problems such as the 'jet collimation'. Two different approaches have been recently proposed and investigated: Vfoil [4] and Foam filled cones [5]. We present here the numerical approach to simulate such phenomena to better understand the mechanism underneath the jet formation. Numerical simulations can serve also as useful tool to guide decisions regarding the future experiments.
Iterative reconstruction of thermally induced phase distortion in a Nd3+:YVO4 laser

The thermal distortions in a continuous-wave end-pumped Nd:YVO4 laser are experimentally investigated by use of an external TEM00 probe beam (TEM standing for transverse electric magnetic). After a round-trip of this probe through the active medium, three irradiance profiles are recorded along its propagation axis. The distorted phase pattern of this probe beam is then reconstructed from these profiles by means of a Gerchberg-Saxton-like iterative algorithm. To identify the contribution of each kind of aberration in the phase profile, we have computed a Zernike polynomial expansion, and have shown that the main terms constituting the aberration are (in order) defocusing (optical path difference (OPD) 0.7 λ FWHM (full width at half-maximum)), spherical aberration (OPD 0.3 λ FWHM), and first-order astigmatism (OPD of ±0.14 λp FWHM). Moreover, all higher-order terms result in a significant phase peak (λ/4 FWHM over 400 µm).
THE SIMPLE LAYER POTENTIAL METHOD OF FUNDAMENTAL SOLUTIONS FOR CERTAIN BIHARMONIC PROBLEMS

SUMMARY A novel formulation of the method of fundamental solutions for the numerical solution of plane biharmonic problems, based on the simple layer potential representation of Fichera, is presented. The applicability and accuracy of the method are demonstrated by examining its performance on a set of practical problems arising in Stokes fluid flow. In recent studies by Karageorghis and Fairweather,'** two formulations of the method of fundamental solutions have been used successfully for the numerical solution of a variety of biharmonic problems. Each of these formulations was proposed by Fairweather and J~hnston. ~ In this paper we examine a third approach suggested by these authors, which is based on a simple layer potential representation of a biharmonic function given by Fichera.4 The biharmonic problem considered in this paper is
Modelling and Simulation of Universal Digital AC Bridge Using Ann Technique

Abstract Bridges are the measuring devices used for accurate measurement of impedance. As such, there is no universal bridge circuit that measures impedance of all types of passive components. Moreover, the bridges available cannot be used for high-frequency impedance measurements. This paper proposes an automatic digital AC bridge model, which is considered to be universal and suitable for high-frequency impedance measurement up to 1MHz. In this adaptive digital AC Bridge, balancing is achieved by means of Artificial Neural Network based on stochastic gradient search algorithm. Among the various gradient search techniques, the Widrow-Hoff's Least Mean Square (LMS) technique has been chosen as it involves less computational burden. The digital AC bridge operations have been verified by simulation. The simulated system was tested for measuring impedances of pure and impure inductors, capacitors, resistors, and a series combination of an inductance and a capacitance. The effects of various parameters like supply voltage, reference resistance, learning rate, and sampling rate were considered to investigate the performance of universal high-precision AC Bridge, and the results are reported. This model is advantageous over the traditional heuristic methods in terms of higher accuracy, faster convergence, and greater reproducibility and reliability.
Infrared emission in paired galaxies. II - Luminosity functions and far-infrared properties

The optical and FIR luminosities and other FIR properties are investigated for pairs of galaxies selected from the Catalog of Isolated Pairs of Galaxies in the Northern Sky. Significant evidence is found for an enhancement in both the optical and FIR emission from galaxies in pairs which can be attributed to interaction-induced star formation activity. The enhancement is seen in the optical luminosity function for all types of pairs, including early-type binaries. At FIR wavelengths, both late-type and mixed morphology pairs show an enhancement in luminosity, FIR-to-optical luminosity ratio, and FIR 60/100 micron color ratio. A significant fraction of these pairs may be involved in direct collisions resulting in the stimulation of excess emission from both pair components. 55 refs.
Wakefield suppression in high gradient linacs for lepton linear colliders

The transverse wakefield excited by multiple bunches in ultrarelativistic charged particle beams in a linear collider must be adequately damped in order to preserve the luminosity of the colliding beams and to prevent a beam breakup instability developing. A review of the means of achieving this wakefield suppression is discussed in detail for normal conducting linacs utilized for linear colliders. In particular, the features of a damped and detuned series of structures are described and compared to other methods. A conspectus of experimental results along with theoretical predictions for this series of accelerating structures developed for the next-linear-collider/global-linear-collider is presented together with the prospects for wakefield suppression for the compact linear collider.
The dependence of EM energy absorption upon human head modeling at 900 MHz

The dependence of electromagnetic energy absorption at 900 MHz in the human head on its anatomy and its modeling are investigated for RF-sources operating in the very close proximity of the head. Different numerical head phantoms based on MRI scans of 3 different adults were used with voxel sizes down to 1 mm/sup 3/. Simulations of the absorption were performed by distinguishing the electrical properties of up to 13 tissue types. In addition simulations with modified electric parameters and reduced degrees of complexity were performed. Thus, the phantoms greatly differ from each other in terms of shape, size, and internal anatomy. The numerical results are compared with those of measurements in a multitissue phantom and 2 homogeneous phantoms of different shapes and sizes. The results demonstrate that size and shape are of minor importance, Although local SAR values depend significantly on local inhomogeneities and electric properties, the volume-averaged spatial peak SAR obtained with the homogeneous phantoms only slightly overestimates that of the worst-case exposure in the inhomogeneous phantoms.
Causality bound on the density of aggregates

The irreversible accretion of diffusing particles onto a large cluster results in a tenuous aggregate characterized by a fractal dimension D0 smaller than that of space. The rate of aggregation onto the fastest-growing sites in such a process must not increase indefinitely as the cluster grows. This fact sets a lower limit on the fractal dimension, viz., the dimension d of space minus 1. For aggregation of ballistically moving particles, this bound implies that the aggregate must be compact: The fractal dimension must equal that of space. In general, if the aggregating particles follow trajectories of fractal dimension D1, the bound implies D0>~d-D1+1.
Theory and simulation of an optical spring mirror

In this paper we present theory and simulations of an optical spring mirror with emphasis on the incident laser beam configuration and the associated optical trapping forces. We elucidate the physical mechanisms underlying the optical trapping using the example of an incident Gaussian beam and demonstrate that guided-wave trapping shows particular promise for stable trapping in both the translational and rotational degrees of freedom.
On-off limit-cycle controllers for reaction-jet-controlled systems

Analytical expressions have been obtained by Mendel [1] for performance cost functions that describe the behavior of a reaction-jet-controlled system during an on-off limit cycle. The cost functions are expressed in terms of the amplitudes of the limit-cycle switch states \theta_{s} and \dot{\theta}_{s} . No structure is assumed for u(t) in [1]. In this paper, u(t) is chosen to be an asymmetrical deadzone function that is proceeded by a T -second time delay. Contained within u(t) are three design variables: control gains K_{\theta} and K_\dot{\theta} , and asymmetry l . This paper shows how \theta_{s} and \dot{\theta}_{s} can be obtained from prespecified values of K_{\theta} and K_{\dot{\theta}} , and how K_{\theta} and K_{\dot{\theta}} can be obtained from prespecified values of \theta_{s} and \dot{\theta}_{s} ; thus, it provides one with the means for utilizing the results in [1] for a specified controller. In addition, conditions are obtained for the existence of an on-off limit cycle. These conditions are interpreted in the phase plane; that is to say, each condition is viewed as a phase-plane constraint or constraints between \theta_{s} and \dot{\theta}_{s} . It is shown how to construct the admissible regions for \theta_{s} and \dot{\theta}_{s} ahead of time. It is also shown how to choose the asymmetry variable l so that limit-cycle existence is assured. All of the results are brought together first as a synthesis procedure, and then as an analysis procedure. Details of both procedures are given. This paper provides the control system designer with new tools for: 1) better understanding the limitations of a fixed controller for the reaction-jet-controlled vehicle; 2) more efficient ways to analyze choices of the controller's parameters on system performance; and 3) more efficient ways to choose these parameters.
Preparation of silver nanoparticles by laser ablation and fragmentation in pure water

Silver nanoparticles were produced by irradiating a silver plate with 1064 nm laser beam in pure water. The effect of the laser fluence and ablation time on the ablation efficiency was studied. Fragmentation of the ablated colloid solution by subsequent treatment with 1064 and 532 nm laser pulses yield redistribution of nanoparticles to a smaller mean size.
Maximizing terminal utility by controlling risk exposure; a discrete-time dynamic control approach

Consider an investor, e.g. an insurance company whose assets evolve according to where the are i.i. d. Thus if is the time of ruin, for , i.e. the process is put on hold after ruin. In an insurance context, the can be absolute net returns of its underwriting business (minus expenses), and the the proportion of the business the company chooses to cover itself. Alternatively, the can be seen as the combined profit ratio, i.e. one minus the combined ratio, and the will then be net premiums. In this context, using the reparametrization , the are the net premium/assets ratio, and in practical insurance this quantity enters frequently in solvency considerations. We seek to choose the , or equivalently the , in order to maximize , with T a fixed terminal time. The maximization is done for “utility” functions of the form with , the case c=1 gives the risk neutral utility function U(y)=y. The optimal solution turns out to be of the form , where is constant for each t, finite or infinite. Given a tolerance level , it is shown that the solvency constraint can be turned into constraints of the form for some fixed α, and the optimal solution under this constraint is again , where now the constants . We also show how to compute the optimal numerically. As an illustration of the theoretical results, three extensive examples are given at the end of the paper.
Effect of Co on the thermal stability and magnetic properties of AlNiCo 8 alloys

The magnetic properties, microstructure, and reversible temperature coefficient of magnetic flux of Alnico 8 alloys with the different Co and Ti have been investigated in this paper. The Alnico alloys containing 34, 36, 38, and 40 mass percent cobalt were fabricated by the conventional casting method including thermomagnetic treatment. The transmission electron microscopy (TEM) testing shows that there are more α1 phases particles with the diameter of less than 10 nm appearing in the matrix with the increasing of the content of Co and Ti. The thermal stability of Alnico 8 alloys deteriorates with the increasing of the content of Co and Ti, which are caused mainly by the decrease of the degree of particle alignment and particle perfection.
A nonlinear negative stiffness metamaterial unit cell and small-on-large multiscale material model

A persistent challenge in the design of composite materials is the ability to fabricate materials that simultaneously display high stiffness and high loss factors for the creation of structural elements capable of passively suppressing vibro-acoustic energy. Relevant recent research has shown that it is possible to produce composite materials whose macroscopic mechanical stiffness and loss properties surpass those of conventional composites through the addition of trace amounts of materials displaying negative stiffness (NS) induced by phase transformation [R. S. Lakes et al., Nature 410, 565-567 (2001)]. The present work investigates the ability to elicit NS behavior without employing physical phenomena such as inherent nonlinear material behavior (e.g., phase change or plastic deformation) or dynamic effects, but rather the controlled buckling of small-scale structural elements, metamaterials, embedded in a continuous viscoelastic matrix. To illustrate the effect of these buckled elements, a nonlinear hierarchical multiscale material model is derived, which estimates the macroscopic stiffness and loss of a composite material containing pre-strained microscale structured inclusions. The multiscale model consists of two scale transition models, the first being an energy-based nonlinear finite element (FE) method to determine the tangent modulus of the metamaterial unit cell, and the other a classical analytical micromechanical model to determine the effective stiffness and loss tensors of a heterogeneous material for small perturbations from the local strain state of the unit cells. The FE method enables the estimation of an effective nonlinear anisotropic stiffness tensor of a buckled microstructure that produces NS and is sufficiently general to consider geometries different from those given in this work.
Design of a wideband excitation source for fast bioimpedance spectroscopy

Multi-frequency-one-time (MFOT) measurement of bioimpedance spectroscopy (BIS) can greatly reduce measurement time and grasp the transient physiological status of a living body compared with the traditional one-frequency-one-time (OFOT) measurement technology, and a wideband excitation source mixed with multiple frequencies is a crucial part of MFOT measurement of BIS. This communication describes a design of a wideband excitation source. Firstly, a multi-frequency mixed (MFM) signal containing seven primary harmonics is synthesized based on Walsh functions, which is a periodical and rectangular signal and whose 68.9% of the energy is homogeneously distributed on its seven 2nth primary harmonics. Then the MFM signal is generated by a field programmable gate array (FPGA), and a unipolar-to-bipolar convertor (UBC) is designed to convert the unipolar signal into bipolar signal. Finally, the bipolar MFM signal is driven by a voltage-controlled current source (VCCS). A 2R-1C series model is adopted as the load of the VCCS, and the simulated voltage response on the load is obtained based on the theoretical analysis. Experiments show that the practical waveform on the load matches well with the theoretical analysis, which indicates that the VCCS has a good performance on the MFM signal. The design of the wideband excitation source establishes a good foundation for fast measurement of BIS.
Stability issues in sensor switching visual servoing

This paper is concerned with camera switching during a visual servoing task using a multi-camera vision system. The concept of dynamical sensor switching is introduced based on image-based and position-based Jacobian transpose control architectures. Stability is discussed extending the Lyapunov-based proof of Kelly et al. to switched system stability using a common Lyapunov function for ideal target and camera models and multiple Lyapunov functions if parameter perturbations are present. Furthermore, an energy supervised switching scheme is proposed as a novel generic extension to switched system visual servoing which significantly reduces the control error only requiring local measurements of control error and system state. The contribution of this work are stable switching visual servoing strategies which facilitate instantaneous adjustments of control performance and dynamical device switches in case of task requirements or sensor breakdown. Further benefits are a possible reduction of the pose error variance over the operating distance and avoidance of singularities resulting from field of view limitations. The switching control schemes are illustrated by simulation studies.
Observers in nonlinear model-based predictive control

A closed-loop reformulation of the dual-mode paradigm affords significant advantages in model-based predictive control of systems subject to uncertainty and/or disturbances and/or nonlinear dynamics. This paper considers earlier results based on ellipsoidal invariant sets and proposes extensions to the output feedback nonlinear case by defining invariant sets both for the system state and the error dynamics of a nonlinear observer. Particular attention is paid to the class of systems with separable nonlinearities but the results carry over to the general case. Copyright © 2000 John Wiley & Sons, Ltd.
THE EXACT VALUE OF THE MOMENTS OF THE DISTRIBUTION OF x2 USED AS A TEST OF GOODNESS OF FIT, WHEN EXPECTATIONS ARE SMALL

IN genetical practice we are constantly presented with large numbers of small samples from populations consisting of several well-defined classes. For example in the mouse we can readily obtain hundreds of litters containing anything from one up to about twelve members. Their totals may agree satisfactorily with expectation on a Mendelian basis, for example J coloured, i white, or 9 grey, H black, i white. But we desire to know whether the individual litters can be regarded as random samples from such a population. In addition the problem of homogeneity may arise. That is to say the population as a whole may not conform to any particular expectation. But we may desire to know whether the litters can be regarded as random samples of the population given by the totals. It has long been known that when the numbers expected in any observation are small, the distribution of x2 departs from that given by Pearson (1900). The mean appears sometimes, but not always, to be equal to the number of degrees of freedom. But the variance is no longer exactly equal to twice that number. Exact expressions for it in certain cases have been given by Pearson (1932) and Cochran (1936). These are based on an ingenious application of the theory of multiple contingency by Pearson. It will be shown in this paper that the first few moments can often be calculated by entirely elementary methods involving nothing more advanced than the multinomial theorem. In an accompanying paper (Griineberg and Haldane, 1937) they will be applied to actual data on mice. We first study the distribution of x2 in a n-fold table with n 1 degrees of freedom, then in a (m x n)-fold table with m (n-i) degrees of freedom. For genetical work we are particularly interested in the (n x 2)-fold table with n degrees of freedom. As a limiting case of the 2-fold table with 1 degree of freedom we derive the moments of the variance of samples from a Poisson series, and thence the distribution of x2 in a n-fold table with n degrees of freedom. The important case of the (m x n)-fold table with (m 1) (n 1) degrees of freedom remains to be investigated. Consider a sample of 8 individuals falling into n classes. Let the expected and observed numbers in these classes be:
Electrical parameters of soils in the frequency range from 1 kHz to 1 GHz, using lumped‐circuit methods

For studying electrical properties of soil samples with various compositions and water contents, we applied a lumped‐circuit approach. The extension of this method up to 1GHz was made possible by using a coaxial sample holder. The complex electrical parameters of soils, such as the relative permittivity , conductivity , and resistivity , were obtained by measuring the magnitude Z and phase ϕ of the sample impedance . The experimental setup is described in our previous paper [Levitskaya and Sternberg, 2000]. The relative real permittivity ε′ and imaginary permittivity (dielectric losses) ε″ for high‐loss soils from Arizona decrease with frequency and increase with water content. Regression equations, derived for the relative permittivity ε′ versus water content at a given frequency, can be used to determine the water content in soil from ε′ data. The third‐degree polynomial equations, which relate the relative permittivity to the volumetric soil moisture content, are different for various frequencies. The complex electrical resistivity components ρ′ and ρ″ reveal a time‐dependent polarization process at frequencies above 1 MHz, which shifts to higher frequencies with increasing water content. The propagation parameters, such as attenuation constant α, phase velocity Vp, and penetration depth P, which we calculated from the electrical parameters, also depend on soil wetness. Our comparison of the electrical and propagation parameters for different soils shows that the high‐loss soil samples from Avra Valley, Arizona, have higher values ε′ and ε″, higher attenuation constant α, and lower penetration depth P than the low‐loss soils from Brookhaven, New York. For example, at 500 MHz, a high‐loss soil (Avra Valley) with volumetric moisture content of ∼10%, exhibits an attenuation of 43 dB/m, whereas for a low‐loss soil (Brookhaven) with the same wetness the attenuation constant is only 4 dB/m. We also note that very dry, clean sand in a sheltered “sand box,” which is a favorite medium for testing ground‐penetrating radar (GPR), is usually not representative of natural conditions. Therefore, GPR data from such “sand box” experiments must be used with considerable caution because they yield unrealistically large penetration depths and unnatural target responses.
Exact and Monte Carlo studies of Gutzwiller's state for the localised-electron limit in one dimension

Exact calculations of the spin-spin correlation function qj in the localised-electron limit of Gutzwiller's (1963, 1965) variational approximation to the Hubbard-model group state, for rings with numbers of electrons N=4(2)18, strongly suggest that qj varies as (-)j/j at large separation j between the spins. Monte Carlo calculations for N up to 100 reproduce this behaviour.