Miracle-dz/UniFAR-FTUs huggingface dataset:
On-chip separation of magnetic particles with different magnetophoretic mobilities

Recent integrations of giant magnetoresistive sensor into laboratory-on-a-chip systems enable the direct detection of biological entities such as cells coated with magnetic particles on chip. However, before detection the different biological entities need to be separated. As a model system, we investigated the separation of two types of magnetic particles (4.5 and 2μm in diameter). The motion of the particles was studied when actuated using an alternating traveling magnetic field produced by four-phase conductors on chip. Different magnetic particles migrate with different speeds in the same traveling magnetic field. By carefully choosing the frequency of the magnetic field, different magnetic particles can be separated in a microfluidic system.
Video-based spatial portraits of a nonlinear vibrating string

The article describes a systematic experimental study of a string vibrating nonlinearly. The string is tracked in real time using strategically located cameras; the video tracking enables a remote observation of the oscillator without perturbing its inherent nonlinearities. We show that our technique can help probe the parametrically excited oscillations and study phenomena such as elliptical and circular trajectories near resonance, resonance fold-over, jump, hysteresis, and subharmonic resonance. The experiment has been successfully employed in the advanced physics laboratory.
Light transmission through two slits: the Young experiment revisited

In the traditional analysis of Young interference it is supposed that the two slits radiate in the same way for any distance between them. In this work, the phenomenon of interference is studied within the framework of the classical electromagnetic theory and in a context that takes into account the mutual interactions between the slits. The results obtained are in agreement with recent experimental values showing how the total transmitted power is enhanced or reduced as a function of the distance between the two slits.
Analysis of deep excavations in clay under the undrained and plane strain condition with small strain characteristics

The nonlinearity and small strain characteristics of clay are predominant factors to affect the analysis accuracy of surface settlement induced by deep excavation in soft clay. In this study, we use a newly developed constitutive model, namely the undrained soft clay model, to simulate the nonlinearity of soft clay and to describe the degradation of elastic Young's modulus with the increasing stress level, ranging from small strain to near failure. The parameters of the formula can be obtained from conventional soil tests. One well-documented case history is then used to show the parameter determination procedure and validate the proposed model. The states of strain and stress paths for the soil in the excavation are also studied to validate the rationality of the model. Besides, two additional case studies are conducted to verify the model further.
Variability in PuO2 Intake by Inhalation: Implications for Worker Protection at the US Department of Energy

This paper describes the stochastic exposure (SE) paradigm where, at most, small numbers of airborne toxic particles are presented for inhalation. The focus is on alpha-emitting plutonium dioxide (PuO 2 ) particles that may be inhaled by Department of Energy (DOE) workers. Consideration of the SE paradigm is important because intake of only a few highly radioactive PuO 2 particles, such as 238 PuO 2 , could greatly exceed the annual limit on intake (ALI) used to control worker exposure. For the SE paradigm, credible intake distributions evaluated over the population at risk are needed, rather than unreliable point estimates of intake. Credible distributions of radiation doses and health risks are also needed. Because there are limited data on humans who inhaled PuO 2 , these distributions must be calculated. Calculated distributions are presented that relate to the intake of radioactivity via inhaling polydisperse PuO 2 particles. The results indicate that a large variability in radioactivity intake is expected when relatively small numbers of PuO 2 particles are inhaled. For the SE paradigm, one cannot know how many PuO 2 particles were inhaled by an individual involved in a given inhalation exposure scenario. Thus, rather than addressing questions such as 'Did the calculated worker's intake of 238 PuO 2 exceed the ALI? ', it is better to address questions such as 'What is the probability that 238 PuO 2 intake by a given worker occurred and exceeded the ALI? ' Mathematical tools for addressing the latter question are presented, and examples of their applications are provided, with emphasis on possible DOE worker exposures at the Rocky Flats facility near Denver, Colorado. The alpha-emitting isotopes 238 Pu, 239 Pu, 240 Pu, and 242 Pu are found at Rocky Flats. Although 238 Pu is thought to be present in relatively small amounts there, intake via inhalation of only a few 238 PuO 2 particles could greatly exceed the ALI.
Nonlinear electron-acoustic waves in a multi-species plasma

Propagation of electron-acoustic waves in a strongly nonlinear magnetoplasma with two ion species is investigated. The presence of the second ion component affects the dynamics of these solitary waves in a variety of ways. Besides solitons, supersonic holes (density depressions) are produced by sufficiently large- amplitude perturbations. Heavier and hotter ions are more favourable to the holes. Applications of the present investigations to space plasmas are pointed out.
A second approximation for the velocity of a large gas bubble rising in an infinite liquid

A second approximation for the velocity of a large gas bubble in an infinite liquid is derived from a linear perturbation of the first approximation. Previously known experimental results are in excellent agreement with the resulting velocity, \[ U = 0.652(g\overline{a})^{\frac{1}{2}}, \] where $\overline{a}$ is the apparent radius of curvature of the front part of the bubble, and g the acceleration due to gravity. The shape of this second approximation is seen to be indistinguishable from spherical over a large region near the front stagnation point.
Benford's Law and the Detection of Election Fraud

The proliferation of elections in even those states that are arguably anything but democratic has given rise to a focused interest on developing methods for detecting fraud in the official statistics of a state's election returns. Among these efforts are those that employ Benford's Law, with the most common application being an attempt to proclaim some election or another fraud free or replete with fraud. This essay, however, argues that, despite its apparent utility in looking at other phenomena, Benford's Law is problematical at best as a forensic tool when applied to elections. Looking at simulations designed to model both fair and fraudulent contests as well as data drawn from elections we know, on the basis of other investigations, were either permeated by fraud or unlikely to have experienced any measurable malfeasance, we find that conformity with and deviations from Benford's Law follow no pattern. It is not simply that the Law occasionally judges a fraudulent election fair or a fair election fraudulent. Its “success rate” either way is essentially equivalent to a toss of a coin, thereby rendering it problematical at best as a forensic tool and wholly misleading at worst.
The effect of heat conduction on the realization of the primary standard for sound pressure

Pressure reciprocity calibration of microphones provides the basis for primary measurement standards for sound pressure in air. At low frequencies, reciprocity calibration requires that a heat conduction correction be employed to account for energy transfer to and from the bounding surfaces of the close-coupled microphone arrangement. The standard governing reciprocity calibration, IEC 61094-2 : 2009, provides two models for the heat conduction correction: the Low Frequency Solution, and the Broadband Solution. Analysis has revealed significant and unexplained differences in behaviour between the models at very low frequencies, leading to inconsistency in calibration results, which has been quantified. Additionally, both heat conduction solutions given in IEC 61094-2 are simplifications that strictly apply only above their respective lower limiting frequencies. An international comparison on microphone calibration is currently underway that includes measurements below the lower limiting frequencies of the models. In this paper, the origin and nature of the Broadband simplifications have been identified, and estimates of the error given. A flaw in the Broadband theory is identified and its effect quantified. Simplification error for the Low Frequency solution is evaluated, and the full spectrum solution is given. This paper urges caution in the application of the models at low frequency and provides data useful for assessing the contribution to the measurement uncertainty.
The Planet-Metallicity Correlation

We have recently carried out spectral synthesis modeling to determine Teff, log g, v sin i, and [Fe/H] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars that have Doppler observations sufficient to detect uniformly all planets with radial velocity semiamplitudes K > 30 m s-1 and orbital periods shorter than 4 yr. From this subset of stars, we determine that fewer than 3% of stars with -0.5 < [Fe/H] < 0.0 have Doppler-detected planets. Above solar metallicity, there is a smooth and rapid rise in the fraction of stars with planets. At [Fe/H] > +0.3 dex, 25% of observed stars have detected gas giant planets. A power-law fit to these data relates the formation probability for gas giant planets to the square of the number of metal atoms. High stellar metallicity also appears to be correlated with the presence of multiple-planet systems and with the total detected planet mass. This data set was examined to better understand the origin of high metallicity in stars with planets. None of the expected fossil signatures of accretion are observed in stars with planets relative to the general sample: (1) metallicity does not appear to increase as the mass of the convective envelopes decreases, (2) subgiants with planets do not show dilution of metallicity, (3) no abundance variations for Na, Si, Ti, or Ni are found as a function of condensation temperature, and (4) no correlations between metallicity and orbital period or eccentricity could be identified. We conclude that stars with extrasolar planets do not have an accretion signature that distinguishes them from other stars; more likely, they are simply born in higher metallicity molecular clouds.
A uniform estimate

In this article we study bilinear operators whose input consists of two functions on the real line and whose output is again a function on the real line. We shall be concerned with a priori estimates for these operators. For simplicity we initially require the two input functions to be Schwartz functions and allow the output function to be a tempered distribution. By abstract generalities such a bilinear operation B can be formally written as
Unsteady Numerical Simulation of Cavitating Turbulent Flow Around a Highly Skewed Model Marine Propeller

The cavitating flows around a highly skewed model marine propeller in both uniform flow and wake flow have been simulated by applying a mass transfer cavitation model based on Rayleigh‐Plesset equation and k- shear stress transport (SST) turbulence model. From comparison of numerical results with the experiment, it is seen that the thrust and torque coefficients of the propeller are predicted satisfactory. It is also clarified from unsteady simulation of cavitating flow around the propeller in wake flow that the whole process of cavitating-flow evolution can be reasonably reproduced including sheet cavitation and tip vortex cavitation observed in the experiments. Furthermore, to study the effect of pressure fluctuation on the surrounding, pressure fluctuations induced by the cavitation as well as the propeller rotation are predicted at three reference positions above the propeller for comparison with the experimental data: The amplitudes of the dominant components corresponding to the first, second, and third blade passing frequencies were satisfactorily predicted. It is noted that the maximum difference of pressure fluctuation between the calculation and experiment reached 20%, which might be acceptable by usual engineering applications. DOI: 10.1115/1.4003355
An improved minimizing algorithm for sum of disjoint products (reliability theory)

The Abraham-Locks-revised (ALR) sum-of-disjoint products (SDP) algorithm is an efficient method for obtaining a system reliability formula. The author describes a minor modification of the ALR algorithm called the Abraham-Locks-Wilson (ALW) method. The new feature is an alternative method of ordering paths and terms. ALW obtains a shorter disjoint system formula on a test example than any previous SDP method and allows small computational savings in processing large paths of complex networks. As there are different ways to obtain a reliability formula it is useful to use an approach which yields the smallest formula relative to computational effort expended. The extra effort in ordering the terms should be reasonably small and usually leads to improved efficiency in the later stages of the algorithm. ALW allows the analyst to operate in a more efficient way on many problems, particularly if the overlap ordering is used in the early stages of processing but is probably ignored for terms that contain a majority of the Boolean variables. >
On the slow motion of a sphere parallel to a nearby plane wall

A new method using a matched asymptotic expansions technique is presented for obtaining the Stokes flow solution for a rigid sphere of radius a moving uniformly in a direction parallel to a fixed infinite plane wall when the minimum clearance ea between the sphere and the plane is very much less than a. An ‘inner’ solution is constructed valid for the region in the neighbourhood of the nearest points of the sphere and the plane where the velocity gradients and pressure are large; in this region the leading term of the asymptotic expansion of the solution satisfies the equations of lubrication theory. A matching ‘outer’ solution is constructed which is valid in the remainder of the fluid where velocity gradients are moderate but it is possible to assume that ε = 0. The forces and couples acting on the sphere and the plane are shown to be of the form (α0+α1ε) log ε + β0 + O(ε) where α0, α1 and β0 are constants which have been determined explicitly.
A numerical study of strained three-dimensional wall-bounded turbulence

Channel flow, initially fully developed and two-dimensional, is subjected to mean strains that emulate the effect of rapid changes of streamwise and spanwise pressure gradients in three-dimensional boundary layers, ducts, or diffusers. As in previous studies of homogeneous turbulence, this is done by deforming the domain of a direct numerical simulation (DNS); here however the domain is periodic in only two directions and contains parallel walls. The velocity difference between the inner and outer layers is controlled by accelerating the channel walls in their own plane, as in earlier studies of three-dimensional channel flows. By simultaneously moving the walls and straining the domain we duplicate both the inner and outer regions of the spatially developing case. The results are used to address basic physics and modelling issues. Flows subject to impulsive mean three-dimensionality with and without the mean deceleration of an adverse pressure gradient (APG) are considered: strains imitating swept-wing and pure skewing (sideways turning) three-dimensional boundary layers are imposed. The APG influences the structure of the turbulence, measured for example by the ratio of shear stress to kinetic energy, much more than does the pure skewing. For both deformations, the evolution of the Reynolds stress is profoundly affected by changes to the velocity–pressure-gradient correlation Πij. This term – which represents the finite time required for the mean strain to modify the shape and orientation of the turbulent motions – is primarily responsible for the difference (lag) in direction between the mean shear and the turbulent shear stresses, a well-known feature of perturbed three-dimensional boundary layers. Files containing the DNS database and model-testing software are available from the authors for distribution, as tools for future closure-model testing.
On the propagation of transversally small‐scale standing Alfven waves in a three‐dimensionally inhomogeneous magnetosphere

In terms of a three-dimensionally inhomogeneous model of the magnetosphere, we have investigated theoretically the process of propagation across the geomagnetic field of monochromatic standing Alfven waves that are transversally small-scale ones. For this purpose we introduced an orthogonal coordinate system tied in a natural manner to the geomagnetic field. It is shown that a three-dimensionally inhomogeneous magnetosphere is composed of sectors that differ from each other by the propagation character of the waves with a different sign of azimuthal wave number. The study revealed the existence of transversally small-scale waves produced near the toroidal surface in one sector and absorbed near this same surface in another sector of the magnetosphere. These phenomena have no analog in the theory of the axisymmetric magnetosphere where oscillations come into being near the poloidal surface and propagate toward the toroidal surface.
Voltage ranking using artificial neural network

Voltage ranking attempts to rank busbar voltage deviations from their normally accepted security margins based on a set of performance indices (PI), without performing a full load flow. Existing methods suffer from either masking effects or long computation time. In this paper, an artificial neural network method is proposed for voltage ranking. Counterpropagation network (CPN) has been employed to overcome the problems listed above. A variety of input features are used with the aim of lowering the dimension of the proposed ANN to make it applicable for large power systems. The method is tested on two example systems, a five‐bus system and a 71‐bus system with very encouraging results.
Using a hidden Markov model to analyse extreme rainfall events in Central‐East Sardinia

The aim of this paper is to investigate the capability of a hidden Markov model (HMM) in identifying possible recurrent patterns in the occurrence of extreme events over a small area of Central‐East Sardinia (Italy), for the purposes of hydrogeological risk prevention. In this area, three intense rainfall events (defined as more than 40 mm in a day) per year are expected during the period September–January. They often assume the characteristics of an extreme event, here defined as more than 100 mm of precipitation in a day. The main interest of modelling daily rainfall data by a HMM lies in the underlying correspondence between the hidden states and the concept of discrete weather states. To model the precipitation at each station, given the weather state, we suggest using a mixture of a point mass at zero and of Weibull distributions, these latter showing a better fit to the considered data than the more usual Gamma and Exponential distributions. Copyright © 2008 John Wiley & Sons, Ltd.
General approach for obtaining joint representations in signal analysis and an application to scale

A general approach for obtaining joint representations in signal analysis is presented. The method is applied to scale representations. We define a new scale operator and show that it leads to joint representations of the Altes and Marinovic type and we also define joint representations with inverse frequency and show that it leads to Bertrand-Bertrand type distributions. We derive the uncertainty principle for scale and obtain the minimum time-scale uncertainty signal.
Comparative Analysis of Nonlinear Dispersive Shallow Water Models

The results of comparative analysis of some nonlinear dispersive models of shallow water are presented. The aim is to find their individual properties relevant for the numerical solution of some model problems of long wave transformation over submerged obstacles The study considers basic properties of the listed models and their numerical implementation. Computations are obtained compared with the analytical solution and experimental data. Attention is primarily focused on the models suggested by Peregrine (1967); Zheleznyak and Pelinovsky (1985); Kim, Reid, Whitakcr (1988): Fedotova and Pashkova (1997). Also classical equations of shallow water are considered in both linear and nonlinear approximations.
Two-dimensional plasma model for the arc-driven rail gun

A previously developed one‐dimensional model for studying the fluid‐mechanical electrodynamical properties of the plasma in an arc‐driven rail gun is extended to two dimensions. The analysis includes deriving a set of general, time‐dependent equations, the solution of which yields the associated properties of the arc. These equations are then solved under the assumptions that the flow variables are steady in a frame of reference which accelerates with the arc, and that the effect of the arc’s acceleration upon these variables can be neglected. Numerical calculations are carried out to analyze arcs in recent experiments. In addition to the numerical calculations, some approximate analytic solutions, which are applicable under certain limiting conditions, are also worked out. These limiting‐case solutions are then used to derive a set of scaling relations which indicate how the arc properties vary with gun size, projectile mass, and acceleration characteristics. Considerable discussion of the assumptions an.
Phonon-like and single-particle dynamics in liquid lithium

The dynamic structure factor, S(Q,E), of liquid lithium (T = 475 K) has been remeasured by inelastic X-ray scattering (IXS) in an extended momentum transfer region (Q = 1.4–110 nm−1) and with improved energy resolution (down to 1.5 meV). These new data on such prototypical simple liquid allow to observe the full evolution with Q from a phonon-like collective mode towards the single-particle dynamics. As a function of Q, one finds: i) at low Q's, a sound mode with a positive dispersion of the sound velocity, ii) at intermediate Q's, excitations whose energy oscillates similarly to phonons in the crystal Brillouin zones, and iii) at high Q's, the S(Q,E) approaches a Gaussian shape, indicating that the single-particle dynamics has been reached.
Positron annihilation study of the electronic structure of URu 2 Si 2 : Fermi surface and hidden order parameter

The Fermi surface (FS) of URu2Si2 in the paramagnetic phase has been reinvestigated via the measurement of the two-dimensional angular correlation of the positron annihilation radiation. Unlike previous measurements our experiment provides evidence that density-functional theory gives a fair qualitative description of the FS, showing a large contribution from the 5f electrons, although the Fermi volume of electron and hole pockets determined experimentally is smaller than the theoretical description. Furthermore, we propose a method to investigate the nature of the hidden order responsible for the 17.5 K transition.
Low-energy electron scatter by Mg I

The electron collisional cross sections for the three lowest states of Mg I are calculated using the close coupling approximation with a semi-empirical core potential. Configuration interaction is included in the Mg I wave functions. Several resonances occur, a few of which strongly affect the total cross sections. Three elastic cross sections (31S-31S, 33P-33P and 31P-31P), and three inelastic cross sections (31S-33P, 31S-31P and 33P-31P) are presented.