Miracle-dz/UniFAR-FTUs huggingface dataset:
A robust numerical method for flow through a pipe driven by an oscillating pressure gradient

The problem of periodic flow of an incompressible fluid through a pipe, which is driven by an oscillating pressure gradient (e.g. a reciprocating piston), is investigated in the case of a large Reynolds number. This process is described by a singularly perturbed parabolic equation with a periodic right‐hand side, where the singular perturbation parameter is the viscosity ν. The periodic solution of this problem is a solution of the Navier–Stokes equations with cylindrical symmetry. We are interested in constructing a parameter‐robust numerical method for this problem, i.e. a numerical method generating numerical approximations that converge uniformly with respect to the parameter ν and require a bounded time, independent of the value of ν, for their computation. Our method comprises a standard monotone discretization of the problem on non‐standard piecewise uniform meshes condensing in a neighbourhood of the boundary layer. The transition point between segments of the mesh with different step sizes is chosen in accordance with the behaviour of the analytic solution in the boundary layer region. In this paper we construct the numerical method and discuss the results of extensive numerical experiments, which show experimentally that the method is parameter‐robust. Copyright © 2006 John Wiley & Sons, Ltd.
Genetic Clustering Algorithms: A Comparison Simulation Study

Abstract In this paper the performance of genetic algorithms for solving some clustering problems is investigated through a simulation experiment. If the number of clusters is known in advance, our results show that the genetic algorithm is able to find the right partition, almost irrespective of the genetic parameters selected. Also, the genetic algorithm always performs favourably with respect to the K-means algorithm. On the other hand, if the number of clusters is unknown, the genetic algorithm provides good results as well. Four versions of the genetic algorithm proposed in the literature are compared, and their performances are not found to differ significantly. However, all algorithms have to be supplied with some reasonable positive integer for the maximum number of clusters. Otherwise, the estimated number of clusters is not very near to the true value. Moreover, if the points are not equally partitioned into clusters, the performances deteriorate considerably. On the contrary, other perturbation sources, such as outliers or data errors, do not affect the results.
Heterogeneous metasurface for high temperature selective emission

We demonstrate selective emission from a heterogeneous metasurface that can survive repeated temperature cycling at 1300 K. Simulations, fabrication, and characterization were performed for a cross-over-a-backplane metasurface consisting of platinum and alumina layers on a sapphire substrate. The structure was stabilized for high temperature operation by an encapsulating alumina layer. The geometry was optimized for integration into a thermophotovoltaic (TPV) system, and was designed to have its emissivity matched to the external quantum efficiency spectrum of 0.6 eV InGaAs TPV material. We present spectral measurements of the metasurface that result in a predicted 22% optical-to-electrical power conversion efficiency in a simplified model at 1300 K. Furthermore, this broadly adaptable selective emitter design can be easily integrated into full-scale TPV systems.
Absorption and scattering of electromagnetic radiation by prismatic columns: anomalous diffraction approximation

Using the anomalous diffraction approximation, we obtain absorption and extinction cross sections of several differently shaped prismatic columns and plates in a simple analytical form. Specifically, we consider columns with triangular, trapezoidal, parallelogram, and hexagonal bases. We estimate the anomalous diffraction approximation results to be within 25% accuracy for refractive indices with real parts up to 1.40 and within 10% accuracy for real parts up to 1.20.
Monte Carlo Procedures in Lighting Design

Consider the problem of illuminating a room. There are ceilings, walls and objects etc., which possess various reflectance characteristics and shapes. Luminaires of various candlepower distributions may be used. The Monte Carlo Method can model surfaces in a way so as to accurately predict a relationship of luminous flux to lighting results.
Performance Predictions for a Pneumatic Active Car Suspension System

A mathematical model of a pneumatic active car suspension system in a single wheel station form excited by realistic road roughness input is set up. The active control is exerted through a d.c. motor-driven air-pump. The model is used to show that essentially all the advantages of active control, within the terms of reference, are obtained by employing the control only at low frequencies and having the suspension parameters adapt to the running conditions as they vary. Control laws are derived using limited state feedback, linear stochastic optimal control theory and power consumption, and space requirements are evaluated. System performance is shown to be good in comparison with other known arrangements and encouragement for further work to extend the results is given.
Estimation in Semiparametric Marginal Shared Gamma Frailty Models

The semiparametric marginal shared frailty models in survival analysis have the non–parametric hazard functions multiplied by a random frailty in each cluster, and the survival times conditional on frailties are assumed to be independent. In addition, the marginal hazard functions have the same form as in the usual Cox proportional hazard models. In this paper, an approach based on maximum likelihood and expectation–maximization is applied to semiparametric marginal shared gamma frailty models, where the frailties are assumed to be gamma distributed with mean 1 and variance θ. The estimates of the fixed–effect parameters and their standard errors obtained using this approach are compared in terms of both bias and efficiency with those obtained using the extended marginal approach. Similarly, the standard errors of our frailty variance estimates are found to compare favourably with those obtained using other methods. The asymptotic distribution of the frailty variance estimates is shown to be a 50–50 mixture of a point mass at zero and a truncated normal random variable on the positive axis for θ0 = 0. Simulations demonstrate that, for θ0 < 0, it is approximately an x−(100 −x)%, 0 ≤x≤ 50, mixture between a point mass at zero and a truncated normal random variable on the positive axis for small samples and small values of θ0; otherwise, it is approximately normal.
Asymptotic Properties of the ISE in Nonparametric Regressions with Serially Correlated Errors

ABSTRACT Ioannides (1992) investigated the asymptotic properties of the integrated square error (ISE) of general kernel estimators of the unknown regression function in nonparametric regression with independent random errors. It is well known, however, that the assumption of independent errors is often violated in practical situations, especially in the analyses of economic data. In this article, we relax this assumption by modeling the errors with a moving average process of infinite order, and establish the asymptotic normality and strong consistency of the ISE by extending the martingale central limit theorem. These results can be used to construct test statistics and make asymptotically efficient statistical inference in nonparametric regressions with serially correlated errors.
Neighbourhood reserve-a measure of locality of the direct interconnection networks

This paper addresses the problem of the design/evaluation of direct interconnection networks by introducing the neighbourhood reserve criterion. The criterion shows how the interconnection structural potential of an interconnection network fits the communication requirements of a parallel process and vice versa. The approach is based on the ideas that any communication model can be well characterised by locality properties and, on the other side, any topology has its intrinsic, structural, locality characteristics. The measure, essentially the difference of the structural neighbourhood and functional neighbourhood, could be used to look for the most suitable structures for a given routing distribution or, inversely, to suggest the most appropriate routing distributions for a given topology. The criterion is illustrated for some known interconnection networks, generalised hypercubes, hypertori and hypergrids, emphasising the locality as one of the main principles of the topological design.
Spin field effect transistor with a graphene channel

A spin field effect transistor (FET) is proposed by utilizing a graphene layer as the channel. Similar to the conventional spin FETs, the device involves spin injection and spin detection by ferromagnetic source and drain. Due to the negligible spin-orbit coupling in the carbon based materials, spin manipulation in the channel is achieved via electrical control of the electron exchange interaction with a ferromagnetic gate dielectric. Numerical estimates indicate the feasibility of the concept if the bias can induce a change in the exchange interaction energy of the order of meV. When nanoribbons are used for a finite channel width, those with armchair-type edges can maintain the device stability against the thermal dispersion.
Specific-heat measurements and critical exponents of the ferroelastic phase transition in Pb 3 ( P O 4 ) 2 and Pb 3 ( P 1 − x As x O 4 ) 2

The ferroelastic phase transitions in ${\mathrm{Pb}}_{3}$${(\mathrm{P}{\mathrm{O}}_{4})}_{2}$ and ${\mathrm{Pb}}_{3}{({\mathrm{P}}_{1\ensuremath{-}x}{\mathrm{As}}_{x}{\mathrm{O}}_{4})}_{2}$ are accompanied by large excess specific heats in a wide temperature range above ${T}_{c}$ and critical crossover above and below ${T}_{c}$. Critical exponents of the specific heat ${\ensuremath{\alpha}}^{\ensuremath{'}}=0.363(4), 0.360(5), \mathrm{and} 0.36(1)$ for ${\mathrm{Pb}}_{3}$(${\mathrm{P}{\mathrm{O}}_{4})}_{2}$, ${\mathrm{Pb}}_{3}$${({\mathrm{P}}_{0.97}{\mathrm{As}}_{0.03}{\mathrm{O}}_{4})}_{2}$, and ${\mathrm{Pb}}_{3}$${{(\mathrm{P}}_{0.2}{\mathrm{As}}_{0.8}{\mathrm{O}}_{4})}_{2}$, respectively, agree with theoretical predictions of a $q=3$, $d=2$, Potts model. Along with other experimental results of neutron and Raman scattering, the specific-heat behavior above ${T}_{c}$ indicates dynamical fluctuations in ${\mathrm{Pb}}_{3}$${(\mathrm{P}{\mathrm{O}}_{4})}_{2}$ and a static intermediate phase in the mixed crystals. A strict proportionality between the transition entropy $\ensuremath{\Delta}S$ and the spontaneous birefringence $\ensuremath{\Delta}{n}_{\mathrm{bc}}$ was observed in ${\mathrm{Pb}}_{3}$(${\mathrm{P}{\mathrm{O}}_{4})}_{2}$ at temperatures up to 415 K. Nonlinear behavior was found close to the transition point (453.6 K), which is interpreted in terms of a multicomponent order-parameter theory.
Bayesian Inference in Multivariate Regression with Missing Observations on the Response Variables

We discuss the case of the multivariate linear model Y = XB + E with Y an (n × p) matrix, and so on, when there are missing observations in the Y matrix in a so-called nested pattern. We propose an analysis that arises by incorporating the predictive density of the missing observations in determining the posterior distribution of B, and its mean and variance matrix. This involves us with matric-T variables. The resulting analysis is illustrated with some Canadian economic data.
Master‐slave synchronization for delayed Lur'e systems using time‐delay feedback control

This paper deals with the problem of designing delayed feedback controllers of master‐slave synchronization for Lur'e systems with time‐variant delay (0≤τ0≤τ(t)≤τm). Through partitioning the intervals [0, τ0] and [τ0, τm], respectively, and choosing two augmented Lyapunov‐Krasovskii functionals(LKFs), two delay‐dependent synchronization criteria are formulated in the form of linear matrix inequalities (LMIs), in which the conservatism can be greatly reduced by thinning the partitioning of delay intervals and employing convex combination. Thus the sufficient conditions can be derived for the existence of delayed feedback controllers, and the controller gain matrices can be achieved by solving the established LMIs. Finally, three numerical examples are given to illustrate the presented synchronization schemes. Copyright © 2010 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Spectro-imaging of the extreme-UV solar corona

This paper describes an instrument concept for imaging spectroscopy of ultraviolet (UV) line emission from the solar corona, in the (30-120) nm wavelength range. The optical design for this Ultraviolet Spectro-Coronagraph (UVSC) instrument concept is an externally occulted, off-axis Gregorian telescope where the secondary mirror is a Toroidal Varied Line-Space (TVLS) grating. A field stop with multiple slits is at the prime focus of the telescope's mirror. This multi-slit field stop is the entrance aperture for the spectrograph. The slits select a number of strips in the field-of-view (FOV) with enough separation to minimize the spectral overlap of the UV lines dispersed by the TVLS grating. The complete two-dimensional imaging of the FOV is obtained by interpolating the slit images along the spectral dispersion direction. This paper discusses the use of an UVSC instrument on HERSCHEL, a NASA sounding-rocket payload. HERSCHEL includes the Sounding-rocket CORonal Experiment (SCORE) that currently comprises a UV Coronagraphic Imager (UVCI) for narrow-band (i.e., λ/Δλ≈10) imaging of the HeII, 30.38 nm, line. Adding a spectroscopic capability (i.e., λ/Δλ ≈ 0.3-1 × 104) to the UVCI would enhance the HERSCHEL's science. This paper presents the ray-tracing results of the expected spectral and spatial performances of a UVSC/SCORE optimised for the HeII, 30.38 nm, line.
Object detection and recognition via stochastic model-based image segmentation

Summary form only given. A stochastic model-based image segmentation technique that utilizes the tone descriptor for object detection and recognition has been developed. The image regions are characterized by region-dependent constant mean (average-gray level) and variance (variation of gray level), and the distribution of the regions is modeled by a stochastic model. For a nondiffracting computed tomography (CT) image it has been proved that (1) at the pixel level, the pixel images are the asymptotic normal random variables, (2) at the class level, the regions are a normal random field, and (3) at the picture level, the observed image is a finite normal mixture. <<ETX>>
Exact solutions of quantum mappings from the lattice KdV as multi-dimensional operator difference equations

The lattice KdV equation is defined on an associative algebra and a new initial value problem on the lattice KdV is considered. This leads to two new families of iterative mappings (discrete equations of motion) which can be solved for all (discrete) times. Imposing a certain commutation relation on the algebra makes it possible to prove (using a Yang–Baxter structure) that these mappings are quantum integrable maps. In the classical limit the maps become a new class of integrable mappings in the sense of Liouville–Arnold–Veselov (LAV).
Multi-Vapor Embryos Nucleation Process and Spinodal Analyses of Expandable Superheated Water System

A homogeneous nucleation process in superheated water is studied with molecular dynamics simulation. System temperature and pressure are controlled with Langevin dynamics and the volume is variable. During the simulation, there can be seen many regions with no molecules, which are termed vapor embryos here. The vapor embryo nucleation and phase transition process of the system is studied phenomenologically. Vapor embryos violate some predictions of classical bubble dynamics theory, which indicate that it is different from bubble. Systems under different temperature are simulated to investigate the effects of superheated rate. The spinodal limit of superheated water at atmospheric pressure is determined at about 535 K.
Suppression of ferroelectric polarization by an adjustable depolarization field

We have measured the effect of a depolarizing field on the properties of a ferroelectric capacitor. By systematically adjusting the amount of charge available to compensate the polarization, we can control the strength of the field inside the ferroelectric. We find that even a few percent of uncompensated polarization charge results in a significant suppression of measured ferroelectric properties, and a complete lack of compensating charge leaves a greatly reduced, although nonzero, polarization. The effect of a depolarizing field is briefly discussed in terms of proposed ferroelectric device applications.
Tribological coatings for complex mechanical elements produced by supersonic cluster beam deposition of metal dichalcogenide nanoparticles

Fullerene-like MoS2 and WS2 nanoparticles can be used as building blocks for the fabrication of fluid and solid lubricants. Metal dichalcogenide films have a very low friction coefficient in vacuum, therefore they have mostly been used as solid lubricants in space and vacuum applications. Unfortunately, their use is significantly hampered by the fact that in the presence of humidity, oxygen and moisture, the low-friction properties of these materials rapidly degrade due to oxidation. The use of closed-cage MoS2 and WS2 nanoparticles may eliminate this problem, although the fabrication of lubricant thin films starting from dichalcogenide nanoparticles is, to date, a difficult task. Here we demonstrate the use of supersonic cluster beam deposition for the coating of complex mechanical elements (angular contact ball bearings) with nanostructured MoS2 and WS2 thin films. We report structural and tribological characterization of the coatings in view of the optimization of tribological performances for aerospace applications.
Geometrical frustration of an argon monolayer adsorbed on the MgO (100) surface: An accurate periodic ab initio study

We present an accurate first-principles method for calculating the energy of physisorption, based on a fully periodic local Moller-Plesset second order perturbation theory (LMP2) treatment. The LMP2 inter-surfaceadsorbate interaction energy is scaled with a factor, obtained by comparing the method error of LMP2 versus coupled cluster singles doubles theory with perturbative triples at the basis set limit in small clusters mimicking the system under study. This method is applied to the investigation of geometrical frustration in argon monolayers adsorbed on the MgO (100) surface. It is found that several arrangements of the argon monolayer, i.e., 3 × 2, 4 × 2, optimal hexagonal, and ζ × 2 1D noncommensurate have very similar adsorption energies, which agrees with the experimental observations. Moreover, this study provides further insight in to the Ar-MgO adsorption process and sheds light on a controversy among different experiments. The calculated adsorption energy of 2.3 kcal/mol is in a very good agreement with the experimental values, which range from 2.0 to 2.3 kcal/mol, and provides a new benchmark for this system.
Performance evaluations of multipath multitarget tracking using PCRLB

In this paper, we study the performance of the multipath-assisted multitarget tracking using multiframe assignment for initiating and tracking multiple targets by employing one or more transmitters and receivers. The basis of the technique is to use the posterior Cramer-Rao lower bound (PCRLB) to quantify the optimal achievable accuracy of target state estimation. When resolved multipath signals are present at the sensors, if proper measures are not taken, multiple tracks will be formed for a single target. In typical radar systems, these spurious tracks are removed from tracking, and therefore the information carried in such target return tracks are wasted. In multipath environment, in every scan the number of sensor measurements from a target is equal to the number of resolved signals received by different propagation modes. The data association becomes more complex as this is in contrary to the standard data association problem whereas the total number of sensor measurements from a target is equal to at most one. This leads to a challenging problem of fusing the direct and multipath measurements from the same target. We showed in our evaluations that incorporating multipath information improves the performance of the algorithm significantly in terms of estimation error. Simulation results are presented to show the effectiveness of the proposed method.
Critical density solitary waves structures in a hot magnetized dusty plasma with vortexlike ion distribution in phase space

The nonlinear properties of solitary waves structures in a hot magnetized dusty plasma consisting of isothermal hot electrons, nonisothermal ions, and high negatively charged massive dust grains are reported. A modified Korteweg–de Vries (modified KdV) equation, which admits a solitary waves solution, for small but finite amplitude, is derived using a reductive perturbation theory. A nonisothermal ion distribution provides the possibility of existence of rarefactive solitary waves. On the other hand, the dynamics of solitary waves at a critical ion density is governed by KdV equation. The modification in the amplitude and width of the solitary waves structures due to the inclusion of obliqueness and external magnetic field are also investigated.
STRUCTURAL PARAMETERS AND LUMINOSITIES OF GLOBULAR CLUSTERS.

The theoretical models of King (1966) are fit to visual photometric data on 106 globular clusters from the Catalog of Concentric Aperture UBVRI Photoelectric Photometry of Globular Clusters (Peterson, 1986) to determine the core radii, concentration classes, central surface brightnesses, and total cluster magnitudes. The results are presented in tables and graphs and compared with those of previous analyses. The present core radii are found to be systematically smaller, by about 0.1 dex in log rc-prime, than those reported by Peterson and King (1975) and Peterson (1976) and to be in good agreement with those of Kron et al. (1983). It is pointed out that accurate determination of cluster concentration class still requires the use of other types of data (e.g., star counts).
Universal shape properties of open and closed polymer chains: renormalization group analysis and Monte Carlo experiments

We investigate the influence of excluded-volume interaction (EV) on the shape of a long flexible polymer chain. Both open chains and ring polymers are considered. We study probability distributions of shape parameters which are typically ratios of characteristic lengths (such as the principal radii of gyration) of a given conformation. For a class of shape parameters such as the «asphericity» A d of a chain in d space-dimensions it is shown how mean values or higher moments of the distributions can be evaluated by field theoretic renormalization group methods. The universality of these distributions is shown and the mean asphericity (A d ) is calculated whithin an e=4-d expansion. (A d ) is found to be much more sensitive to the EV than a frequently used asphericity-approximant which avoids the ratio-averaging. This is ths first analytical confirmation of a result observed by other groups in numerical simulations. We also investigate the complete distribution of A 3 and of another (prolate vs. oblate) shape parameter in d=3 by means of Monte Carlo simulations. The dependence on chain length is carefully investigated. The improves the accuracy of previous estimates of universal asymptotic shape distributions. Generally the EV makes the shape more aspherical and prolate. Comparing quantitatively the increase in (A 3 ) due to the EV as implied by the Monte Carlo data with that by the (appropriately extrapolated) first order e-expansion one finds good [fair] agreement in case of ring polymers [open chains]