Miracle-dz/UniFAR-FTUs huggingface dataset:
Non-Subsampled Contourlet Texture Retrieval Using Four Estimators

Contourlet transform is superior to wavelet transform in representing texture information and sparser in describing geometric structures in digital images, but lack of robust character of shift invariance. Non-subsampled contourlet transform (NSCT) alleviates this shortcoming hence more suitable for texture and has been studied for image de-noising, enhancement, and retrieval situations. Focus on improving the retrieval rates of existing contourlet transforms retrieval systems, a new texture retrieval algorithm was proposed. In the algorithm, texture information was represented by four statistical estimators, namely, L2-energy, kurtosis, standard deviation and L1-energy of each sub-band coefficients in NSCT domain. Experimental results show that the new algorithm can make a higher retrieval rate than the combination of standard deviation and energy which is most commonly used today.
Direct, adjoint and mixed approaches for the computation of Hessian in airfoil design problems

In this paper, four approaches to compute the Hessian matrix of an objective function used often in aerodynamic inverse design problems are presented. The computationally less expensive among them is selected and applied to the reconstruction of cascade airfoils that reproduce a prescribed pressure distribution over their walls, under inviscid and viscous flow considerations. The selected approach is based on the direct sensitivity analysis method for the computation of first derivatives, followed by the discrete adjoint method for the computation of the Hessian matrix. The applications presented in this paper show that the Newton method, based on exact Hessian matrices, outperforms other gradient‐based algorithms such as steepest descent or BFGS algorithm. Copyright © 2007 John Wiley & Sons, Ltd.
Nonhydraulic Effects in Particle‐Driven Gravity Currents in Deep Surroundings

In this article, we present an approach to modeling the flow of particle‐driven gravity currents produced by the sudden release of well‐mixed, fixed‐volume suspensions into deep surroundings. Our model accounts for the initial turbulent energy of mixing in the release volume, characteristic of the classical lock–release experiments, as well as the spatiotemporal variability in the driving buoyancy forces attributable to particle settling. We show that, in contrast to compositionally driven flows, particle‐driven flows cannot be described consistently in terms of shallow water theory. Specifically, we show that the presence of particles in the flow dynamics produces significant horizontal velocity shear, thereby changing the flow configuration in important ways from flows assumed to be governed by the shallow water equations. These new flow properties are calculated and contrasted with flow properties derived on the basis of the shallow water equations to show that the shallow water analysis misses dynamical features of the flow. We also show that our model provides significant improvement over the previous shallow water‐based models in predicting the experimentally determined deposition patterns associated with the lock–release experiments.
Supergranulation as an Emergent Length Scale

We have developed an n-body diffusion-limited aggregation model to simulate the dispersal and interaction of small-scale magnetic elements at the solar surface. The model is highly simplified and is based on the observation that small-scale magnetic elements are passively advected by the granular flow, which we approximate as a random walk. With a great many magnetic elements executing this random walk simultaneously, collisions are inevitable. We assume that these collisions lead to the aggregation of the colliding magnetic elements (if they have the same polarity) or mutual cancellation (if opposite polarity). In a similar fashion, the resulting clusters can subsequently interact with more magnetic elements or with other clusters. The clusters also undergo a random walk. However, the step size is reduced and the lifetime is increased in order to mimic the observation that larger magnetic flux concentrations move slower and live longer than smaller ones. The essential finding is that this process can produce a spatial distribution of clusters comparable to the supergranule cell pattern (depending on model parameters). The characteristic length scale associated with the spatial distribution of the clusters is quite sensitively dependent on the injection rate of fresh magnetic elements—when the injection rate is high (low) the length scale is small (large). This property provides a natural explanation for the observation that supergranule cells tend to be smaller when and where the level of magnetic activity is higher. We also find that at length scales similar to supergranulation the dominance of a given polarity tends to be enhanced, in comparison to the case where the same clusters are situated randomly in space. This is potentially testable by observation.
On the forces acting on a circular cylinder set obliquely in a uniform stream at low values of Reynolds number

The forces acting on a circular cylinder set obliquely to a uniform stream of an incompressible viscous fluid are discussed for small values of Reynolds number. The total force on the cylinder is calculated by resolving it into the transverse and longitudinal components, N and L, and the general formulae as well as expansion formulae in powers of the Reynolds number axe given for these two components. Further, a certain relation between the component due to the tangential stress rθ͡͡ on the surface, of the transverse force N and the longitudinal force L is examined at low values of the Reynolds number; this relation has been obtained recently by Sir Geoffrey Taylor for larger values of the Reynolds number. The present work is intended to make some contribution to a new field in hydrodynamics which has been developed by Sir Geoffrey Taylor in connexion with the mechanics of swimming of long and narrow animals in a viscous fluid.
Optimal disturbances and bypass transition in boundary layers

Streamwise streaks are ubiquitous in transitional boundary layers, particularly when subjected to high levels of free-stream turbulence. Using the steady boundary-layer approximation, the upstream disturbances experiencing maximum spatial energy growth are numerically calculated. The calculations use techniques commonly employed when solving optimal-control problems for distributed parameter systems. The calculated optimal disturbances consist of streamwise vortices developing into streamwise streaks. The maximum spatial energy growth was found to scale linearly with the distance from the leading edge. Based on these results, a simple model for prediction of transition location is proposed. Available experiments have been used to correlate the single constant appearing in the model.
Perception of vowel sequence with varying speaker size

Speech sounds convey information about the size of the speaker. Several studies have demonstrated that human vowel recognition is possible even for an unnatural size range, and have revealed that size factor normalization can be achieved automatically in the auditory system. In this study, we further investigated the characteristics of the size normalization process, using vowel sequences with temporal changes in the speaker size. In the current experiments, listeners were presented with six-vowel sequences in which the vocal-tract length was alternated vowel by vowel. The experimental results for the identification of the vowel sequence showed that it was increasingly difficult for listeners to identify vowels in the correct order as size alternation was applied with a higher speed and to a larger degree. However, they showed the high performance of vowel recognition when serial order judgment between vowels was not required, and in this case the performance deterioration caused by size alternation became small. The observed deterioration of sequence identification is likely to have been caused not by a failure in size normalization in the auditory system but because of a difficulty in judging the serial order between vowels in the sequence with rapid size changes. The results suggest that the auditory system has a fast process for normalizing speaker-size information and that it operates appropriately even when a sequence contains the temporal alternation of vocal-tract length.
Dynamic traffic grooming for port number optimization in WDM optical mesh networks

In this paper, the objective was optimizing the port number with dynamic traffic grooming of SDH/SONET WDM mesh networks to give useful referenced data to networks design and the cost control of networks. The performances of different path select routing algorithms were evaluated in WDM grooming networks by considering traffic of different bandwidth requests. Finally, the results were presented and compared with in distributed-controlled WDM mesh networks.
Steepest‐descent moment method for three‐dimensional magnetohydrodynamic equilibria

An energy principle is used to obtain the solution of the magnetohydrodynamic (MHD) equilibrium equation J×B−∇p=0 for nested magnetic flux surfaces that are expressed in the inverse coordinate representation x=x(ρ, θ, ζ). Here, θ are ζ are poloidal and toroidal flux coordinate angles, respectively, and p=p(ρ) labels a magnetic surface. Ordinary differential equations in ρ are obtained for the Fourier amplitudes (moments) in the doubly periodic spectral decomposition of x. A steepest‐descent iteration is developed for efficiently solving these nonlinear, coupled moment equations. The existence of a positive‐definite energy functional guarantees the monotonic convergence of this iteration toward an equilibrium solution (in the absence of magnetic island formation). A renormalization parameter λ is introduced to ensure the rapid convergence of the Fourier series for x, while simultaneously satisfying the MHD requirement that magnetic field lines are straight in flux coordinates. A descent iteration is also d.
Line spectrum representation of linear predictor coefficients of speech signals

It has been known that the linear predictor coefficients (LPC) of speech signals can be transformed into a “pseudo” vocal‐tract area function whose boundary conditions are (a) a complete opening at the lips and (b) a matching resistance termination at the glottis. If the boundary condition at the glottis is replaced by a complete opening or a complete closure, all the poles of the resulting system function will move onto the unit circle in z plane. Using this fact it is possible to describe the original LPCs by two sets of pole frequencies corresponding to the two new boundary conditions at the glottis, or a set of frequency‐residue pairs corresponding to either set of poles. These representations have several important features: (1) If an original pole is narrow band, the new pole is close to the original pole; (2) the two sets of pole frequencies alternate and are ordered on the frequency axis; and (3) the problem of locating complex poles can be reduced to solving a polynomial with real roots whose ord.
Optical reconstruction of three-dimensional object from digital holograms using phase information calculated by continuous wavelet transform

We propose to record digital Fourier hologram of a 3D diffused object and to reconstruct numerically and optically by using phase-only information. This phase-only information is obtained by using 1D-Continuous Wavelet Transform (1DCWT) from the intensity of digital Fourier Hologram. 3D object image is obtained by numerical reconstruction on computer and optical reconstruction by using a phase-modulated liquid crystal spatial light modulator (SLM). Numerical and experimental results are presented.
Analysis of hysteresis motor using finite element method and magnetization-dependent model

In this paper, finite element analysis (FEA) of a hysteresis motor using a magnetization-dependent model is presented. The hysteresis loop in the hysteresis ring is calculated from the maximum flux density which is obtained by the FEA. The proposed method is applied to a sample motor and the simulation result shows a very good agreement with the experimental one. Various formulations for hysteresis region are compared and it is found that pseudo-permeability method is most effective.
Discovery of two fast-rotating pulsars

Two fast-rotating pulsars have been discovered at high Galactic latitudes in the course of a systematic survey with the Arecibo telescope. PSR J2235+1506 has a period of 59.7 ms, a small magnetic field, and a spin-down time scale in excess of 10 9 yr. It is only the third such object known (outside of globular clusters) which is not a member of a binary system. PSR J2317+1439 is a 3.4 ms pulsar in a 2.46 day orbit with a ∼0.2 M ○. companion. Its orbital eccentricity e=(1.2±0.8)×10 −6 is, to our knowledge, the smallest known for an orbiting object of any kind. We briefly discuss some characteristics of the rapidly growing sample of field millisecond pulsars
Transport equations for freely propagating photons in curved spacetimes: a derivation by Wigner transformation

Starting from the homogeneous wave equations for the expectation value of the two-point correlation tensor of the electromagnetic field, a transport equation for photons in curved spacetimes is derived by making use of the covariant generalisation of the Wigner transformation. Two linear differential equations on the tangent bundle are obtained whose correction terms to the well known Liouville equation and the classical mass-shell condition are of the order of the wavelength over the variation length of the background geometry. In the same way a transport equation for the distribution tensor is derived, which describes (partially) polarised light completely.
A hierarchical CMAC architecture for context dependent function approximation

A hierarchical cerebellar model articulation controller (CMAC) architecture suitable for context-dependent function approximation is proposed. The objective is to approximate several distinct nonlinear functions, one for each of several contexts. The active context is determined from the values of context variables, and smooth interpolation between different contexts is possible. The learning algorithms used can be similar to those of the hierarchical mixtures of experts (HME) as CMAC networks are linear in parameters. The proposed architecture converges quickly and has very low computational requirements when first order learning algorithms are used. The effectiveness of the architecture is demonstrated on a composite nonlinear regression task involving three Gaussian functions.
Nanotubes in boron nitride laser heated at high pressure

Here we report on the finding of pure boron nitride (BN) nanotubes that do not contain any additional inclusions and on a new method for their growth: laser heating of boron nitrides at high nitrogen pressure (5–15 GPa). The multiwalled nanotubes were observed using high resolution electron microscopy and were chemically characterized by electron energy loss spectroscopy. The circular or polygonal cross‐sectional nanotubes, which have 3–8 shells and a characteristic outer dimension cross section of 3–15 nm, were found to have grown either in melted cubic BN or in hexagonal+amorphous BN that had recrystallized on the specimen’s surface from the fluid phase.
No-reference peak signal to noise ratio estimation based on generalized Gaussian modeling of transform coefficient distributions

We present a no-reference peak signal to noise ratio (PSNR) estimation algorithm based on discrete cosine transform (DCT) coefficient distributions from H.264/MPEG-4 part 10 advanced video codec (H.264/AVC) bitstreams. To estimate the PSNR of a compressed picture without the original picture on the decoder side, it is important to model the distribution of transform coefficients obtained from quantized coefficients accurately. Whereas several conventional algorithms use the Laplacian or Cauchy distribution to model the DCT coefficient distribution, the proposed algorithm uses a generalized Gaussian distribution. Pearson's χ 2 (chi-square) test was applied to show that the generalized Gaussian distribution is more appropriate than the other models for modeling the transform coefficients. The χ 2 test was also used to find optimum parameters for the generalized Gaussian model. It was found that the generalized Gaussian model improves the accuracy of the DCT coefficient distribution, thus reducing the mean squared error between the real and the estimated PSNR.
Mechanisms of impulsive pressure generation and damage pit formation by bubble collapse

A detailed experimental study has been made to clarify the mechanism of impulsive pressure generation from a single bubble collapsing in a static fluid – this is the most essential and important research task concerned with cavitation damage. First, the general feature of impulsive pressure generation is discussed, and then the impulsive pressure directly contributing to damage is investigated by various means. As a result, it is found that the impulsive pressure causing plastic deformation of material is closely related, directly or indirectly, to the behaviour of a liquid jet. Further more, it is demonstrated that the interaction of a tiny bubble with a shock wave or a pressure wave must be an important effect in producing a local high pressure which causes damage to material. The damage pit caused by the bubble-shock-wave interaction essentially results from the impact pressure from a liquid microjet.
Multi-ferroic magnetoelectrics

Abstract Domain aspects of multi-ferroics are reviewed, i.e. of materials, in which two or all three of the properties ‘ferroelectricity. ’ ‘ferromagnetism’ and ‘ferroelasticity’ occur simultaneously in the same phase, and in which the magnetic point group has been reliably established by magnetoelectric, optical, dielectric, magnetic and related studies on single crystals and single domains. Nearly only members of the boracite crystal family are concerned, whereas for the perovskite family and other classes of material there is great paucity of data on single crystals. Polarized light microscopy is shown to be an indispensable tool for the study of multi-ferroics, in particular when ferroelasticity is involved. Potential multi-ferroic magnetoelectrics, so far only known in ceramic form, are excluded from the survey.
Ridgelet decomposition: discrete implementation and color denoising

In this paper, we review an implementation of the Ridgelet transform: The Discrete Analytical Ridgelet Transform (DART). This transform uses the Fourier strategy for the computation of the associated 2-D and 3-D discrete Radon transforms. The innovative step is the definition of a discrete 3-D transform and the construction of discrete analytical lines in the Fourier domain. These discrete analytical lines have a parameter called arithmetical thickness, allowing us to define a DART adapted to a specific application. Indeed, the DART representation is not orthogonal, it is associated with a flexible redundancy factor. The DART has a very simple forward/inverse algorithm that provides an exact reconstruction without any iterative method. We had proved in different publications that the 2D and 3D DART are performant for the level of greys images restorations. Therefore we have interesting to 2D/3D color image restorations. We have compared the restoration results in function of different color space definition and importance of the white Gaussian noise. We criticize our results with two different measures : the Signal Noise Ratio calculation and perceptual measures to evaluate the perceptual colour difference between original and denoised images. These experimental results show that the simple thresholding of the DART coefficients is competitive than classical denoising techniques.
Self-adaptive characteristics segmentation optimized algorithm of weld defects based on flooding

In order to improve the accuracy and efficiency of weld defect segmentation in automatic radiographic nondestructive testing and evaluation（NDT&E）, an effective weld defect segmentation algorithm based on flooding has been developed, which has the self-adaptive characteristics. Firstly, the defect’s feature points are extracted from the scale space of radiographic films. Based on the information of defect points, the seed points and seed domains of defect discrimination are adaptively determined, in which the defect segmentation seed will be searched. Then, aiming at the sparsity of weld defects and canyon characteristics of 3D topographic map of defect regions, the drip-watering and water flooding have been used for reference. The flooding is carried out by using line-flooding algorithm, in which water starts from defect seed points and flows to the neighbor regions in order. On the basis of the flooding-area change and flooding-level ascending velocity, the defect segmentation threshold values are determined and the weld defects also are segmented from the radiographic films. At last, the comparative experiments have been carried out to compare the proposed algorithm with the watershed segmentation algorithm and background subtraction segmentation algorithm. And the experiment results confirm that the proposed algorithm obviously improves the accuracy and efficiency of weld defect’s segmentation.
A silicon MEMS optical switch attenuator and its use in lightwave subsystems

A single-mode fiber connectorized microelectromechanical systems (MEMS) reflective optical switch attenuator operating in the 1550-nm wavelength region is described. The device consists of an electrostatically actuated gold-coated silicon vane interposed in a fiber gap yielding 0.81-dB minimum insertion loss in the transmit state and high transmission isolation in the reflection state with 2.15-dB minimum return loss. The switch attenuators also work as continuously variable optical attenuators capable of greater than 50-dB dynamic range and can be accurately regulated with a simple feedback control circuit. Switching voltages were in the range of 5-40 V and a switching time of 64 /spl mu/s was achieved. The MEMS switch can be used in optical subsystems within a wavelength-division-multiplexed (WDM) optical network such as optical power regulators, crossconnects, and add/drop multiplexers. We used a discrete array of 16 switch attenuators to implement a reconfigurable 16-channel 100-GHz spacing WDM drop module of an add/drop multiplexer. Thru-channel extinction was greater than 40 dB and average insertion loss was 21 dB. Both drop-and-transmit of multiple channels (11-18-dB contrast, 14-19-dB insertion loss) and drop-and-detect of single channels (>20-dB adjacent channel rejection, 10-14-dB insertion loss) were demonstrated.
Partial inverse regression

In regression with a vector of quantitative predictors, sufficient dimension reduction methods can effectively reduce the predictor dimension, while preserving full regression information and assuming no parametric model. However, all current reduction methods require the sample size n to be greater than the number of predictors p. It is well known that partial least squares can deal with problems with n < p. We first establish a link between partial least squares and sufficient dimension reduction. Motivated by this link, we then propose a new dimension reduction method, entitled partial inverse regression. We show that its sample estimator is consistent, and that its performance is similar to or superior to partial least squares when n < p, especially when the regression model is nonlinear or heteroscedastic. An example involving the spectroscopy analysis of biscuit dough is also given. Copyright 2007, Oxford University Press.