Miracle-dz/UniFAR-FTUs huggingface dataset:
Seismic analysis of arch dams—a continuum damage mechanics approach

In this paper, the non-linear seismic response of arch dams is presented using the concept of Continuum Damage Mechanics (CDM). The analysis is performed using the finite element technique and appropriate non-linear material and damage models in conjunction with the α-algorithm for time marching. Because of the non-linear nature of the discretizied equations of motion, modified Newton–Raphson approach has been used at each time step. Damage evolution based on tensile principal strain using mesh-dependent hardening modulus technique is adopted to ensure the mesh objectivity and to calculate the accumulated damage. The methodology employed is shown to be computationally efficient and consistent in its treatment of both damage growth and damage propagation. As an application of the proposed formulation, a double curvature arch dam has been analysed and the results are compared with the solutions from linear analysis and it is shown that the structural response of arch dams varies significantly in terms of damage evolution. Copyright © 1999 John Wiley & Sons, Ltd.
Robust detection of small infrared objects in maritime scenarios using local minimum patterns and spatio-temporal context

Here, we describe a novel approach for small surface object detection with an onboard infrared (IR) camera working in maritime scenes. First, we propose a simple but effective tool called the local minimum patterns (LMP), which are theoretically the approximated coefficients of some stationary wavelet transforms, for single image background estimation. Second, potential objects are segmented by an adaptive threshold estimated from the saliency map, which is obtained by background subtraction. Using the LMP based wavelet transforms and the histogram of the saliency map, the threshold can be automatically determined by singularity analysis. Next, we localize potential objects by our proposed fast clustering algorithm, which, compared with popular K-Means, is much faster and less sensitive to noises. To make the surveillance system more reliable, we finally discuss how to integrate multiple cues, such as scene geometry constraints and spatio-temporal context, into detections by Bayesian inference. The proposed method has shown to be both effective and efficient by our extensive experiments on some challenging data sets with a competitive performance over some state-of-the-art techniques.
The stellar populations of M 33

content of the Triangulum nebula = M 33 = NGC 598. A distance modulus of (m - M)0_=24.5 ± 0.2 (D = 795 ± 75 kpc) and a Galactic foreground reddening EB-V_=0.07, from which MV_= - 18.87, are adopted throughout this paper. The disk of M 33 is embedded in a halo of globular clusters, ,metal- poor red giants, and RR Lyrae stars. Its nuclear bulge component is weak (MV_ > -14). This suggests that the halos of galaxies are not extensions of their bulges to large radii. The ages of M 33 clusters do not appear to exhibit a hiatus in their star-forming history like that which is observed in the Large Magellanic Cloud. Young and intermediate-age clusters with luminosities rivaling the populous clusters in the LMC are rare in M 33. The integrated light of the semistellar nucleus of M 33, which contains the strongest X-ray source in the Local Group, is dominated by a young metal-rich population. At optical wavelengths the disk scale length of M 33 is 9.6', which is similar to the 9.9' scale length of OB associations. The ratio of the nova rate in M 33 to that in M 31 is approximately equal to the ratio of their luminosities. This suggests that the nova rate in a galaxy is not determined entirely by the integrated luminosity of old bulge stars. The gas-depletion time scale in the central region of M 33 is found to be ~1.7 X 109^ yr, which is significantly shorter than a Hubble time. Available data do not yet allow an unambiguous choice between the density wave and self-propagating star-formation models for the two main spiral arms of M 33.
Magnetic and viscous coupling at the core—mantle boundary: inferences from observations of the Earth's nutations

SUMMARY Dissipative core‐mantle coupling is evident in observations of the Earth’s nutations, although the source of this coupling is uncertain. Magnetic coupling occurs when conducting materials on either side of the boundary move through a magnetic field. In order to explain the nutation observations with magnetic coupling, we must assume a high (metallic) conductivity on the mantle side of the boundary and a rms radial field of 0.69 mT. Much of this field occurs at short wavelengths, which cannot be observed directly at the surface. High levels of short-wavelength field impose demands on the power needed to regenerate the field through dynamo action in the core. We use a numerical dynamo model from the study of Christensen & Aubert (2006) to assess whether the required short-wavelength field is physically plausible. By scaling the numerical solution to a model with sufficient short-wavelength field, we obtain a total ohmic dissipation of 0.7‐1 TW, which is within current uncertainties. Viscous coupling is another possible explanation for the nutation observations, although the effective viscosity required for this is 0.03 m 2 s −1 or higher. Such high viscosities are commonly interpreted as an eddy viscosity. However, physical considerations and laboratory experiments limit the eddy viscosity to 10 −4 m 2 s −1 , which suggests that viscous coupling can only explain a few percent of the dissipative torque between the core and the mantle.
Magnets for a muon storage ring

We present a new racetrack coil magnet design, with an open midplane gap, that keeps decay particles in a neutrino factory muon storage ring from directly hitting superconducting coils. The structure is very compact because coil ends overlap middle sections top and bottom for skew focusing optics. A large racetrack coil bend radius allows "react and wind" magnet technology to be used for brittle Nb/sub 3/Sn superconductors. We describe two versions: Design-A, a magnet presently under construction and Design-B, a further iterated concept that achieves the higher magnetic field quality specified in the neutrino factory feasibility Study-II report. For Design-B reverse polarity and identical end design of consecutive long and short coils offers theoretically perfect magnet end field error cancellation. These designs avoid the dead space penalty from coil ends and interconnect regions (a large fraction in machines with short length but large aperture magnets) and provide continuous bending or focussing without interruption. The coil support structure and cryostat are carefully optimized.
Audio acoustic modeling using full‐wave methods

The numerical simulation of wave propagation poses a significant challenge in scientific computation. Historically, several approaches are explored in order to get a stable method that can be efficiently used for approximating wave propagation without excessive numerical dissipation or dispersion. Unfortunately, the traditional approaches, such as the finite element and the finite difference, require many discretization points per wavelength to obtain reliable solutions. In this study, two alternative full‐wave methods for reducing the computational complexity are consider. The methods are the time‐domain discontinuous Galerkin method and the ultraweak variational formulation in the frequency domain. Using these techniques, the directivity and the frequency response of a loudspeaker are studied. Moreover, the simulated results are compared to experimental measurements.
Approximately-finite memory and input-output maps

Results are given concerning the character of the response of systems represented by approximately-finite-memory input-output maps, G. Conditions are given under which. for example, the system's output approaches a limit as t to infinity whenever the input does. Of particular interest are results that concern the existence and properties of a certain unique extension of G to a corresponding domain of functions defined on all of (- infinity , infinity ). Those theorems lead to some general propositions that characterize the response of nonlinear systems to asymptotically almost periodic inputs. These concern, for example the spectrum of the system's steady-state output as well as an analytical basis for the computation of the steady-state output. <<ETX>>
Distribution and evolution of high-z galaxies in the Subaru/XMM-Newton Deep Survey Field (SXDF)

Abstract We present results from our on-going study of the distribution and evolution of high-z galaxies. We exploited the large area coverage (~1.3 deg2) of the Subaru / XMM-Newton Deep Survey field (SXDF) to search for Lyman-break galaxies (LBGs) and Lyα Emitters (LAEs) at 3 <z< 7. We have found filamentary large scale structures, which are made of LAEs, with ~10 to 40 Mpc (in commoving units) scale voids as early as at z = 5.7. Galaxies at this redshift show clustering of ~1 Mpc in diameter (in physical unit). The inferred star formation rate density of these clustering is ~130 times the mean of the whole area, indicates burst of star formation activities. Combined with the UKIDSS/UDS photometry, the optical+near-IR SED fitting provides the estimate of masses for some of these high-z galaxies. Preliminary results indicate a number of galaxies at z >5 have already grown up to ~1011 solar mass.
Formation of very strongly magnetized neutron stars - Implications for gamma-ray bursts

It is proposed that the main observational signature of magnetars, high-field neutron stars, is gamma-ray bursts powered by their vast reservoirs of magnetic energy. If they acquire large recoils, most magnetars are unbound from the Galaxy or reside in an extended, weakly bound Galactic corona. There is evidence that the soft gamma repeaters are young magnetars. It is argued that a convective dynamo can also generate a very strong dipole field after the merger of a neutron star binary, but only if the merged star survives for as long as about 10-100 ms. Several mechanisms which could impart a large recoil to these stars at birth, sufficient to escape from the Galactic disk, are discussed.
Robust eigenvalue/eigenvector selection in linear state feedback systems

Design procedures are developed to select both eigenvalues and eigenvectors to improve system robustness. A robustness metric based on the determinant of the normalized eigenvector matrix defined. It is shown that this metric significantly speeds up the convergence of robust eigenvector solutions close to the optimal. A procedure to blend multiple inputs to improve achievable system robustness in the lower dimensional pseudo control space has also been derived. <<ETX>>
Free vibration Analysis of Laminated Plates using Wavelet Collocation and a Unified Formulation

A study of free vibrations of shear flexible isotropic and laminated composite plates with the Carrera’s unified formulation is presented. The analysis is based on collocation with a Deslaurier Dubuc interpolating basis to produce highly accurate results. The high order collocation method presented in this paper proved to be very accurate for this type of problems and the numerical efficiency is as good as other numerical schemes, such as finite element solutions.
Hot spot heating process estimate using a laser-accelerated quasi-Maxwellian deuteron beam

The hot spot heating process by an assumed deuteron beam is evaluated in order to estimate the contribution of the energy produced by the deuteron beam-target fusion to the heating process. The deuteron beam energy versus the number of deuterons is evaluated through the experimentally achieved proton beam energy distribution using the TRIDENT short pulse laser at the Los Alamos National Laboratory (LANL). The corresponding hot spot heating is then calculated using this assumed deuteron beam spectrum. The resulting first order heating dynamics is employed in the expanded “bonus” energy calculation, and a 12.73% extra energy from deuteron beam-target fusion was found with the assumed deuteron spectrum when ρrb =4.5 g/cm 2 is considered, where ρ is the fuel density, and rb is the ion beam focusing radius on the target. The results provide further insight into the contribution of the extra heat produced by deuteron beam-target fusion to the hot spot ignition process. A further analysis of how a converter foil using ultra-high-density cluster materials can help to achieve the yield requirements for ignition is presented.
All-optical tunable notch filter by use of Kerr nonlinearity in the graphene microribbon array

We report a numerical study on the optical tuning of a notch filter comprised of an array of engineered graphene microribbons. The notch on the normal incidence transmission spectra is created due to light–plasmon coupling in graphene. Besides investigating the effect of structural parameters and electrostatic gating on the graphene plasmon excitation, we particularly examine the modulation of transmission with incident light intensity based on the significant optical Kerr effect in graphene. Our numerical simulation with the finite difference time domain numerical method reveals that considerable variation in the transmission up to 12.15 dB can be effectively achieved by increasing the irradiance intensity up to 0.68 MW/cm2, which is adequately below the graphene threshold damage. The presence of well-known techniques to fabricate and characterize graphene sheets such as chemical vapor deposition and Raman spectroscopy makes such a one-atom-thick terahertz filter feasible.
High‐order three‐dimensional discontinuous deformation analysis (3‐D DDA)

Three‐dimensional discontinuous deformation analysis (3‐D DDA) with high‐order displacement functions has been derived for the requirement of highly accurate stress and strain calculations. The high‐order displacement function allows nonlinear distributions of stresses and strains within a discrete block, which significantly enhances 3‐D DDA as an analysis technique. Formulations of stiffness and force matrices in second‐ and third‐order 3‐D DDA due to elastic stress, initial stress, body force, point load, fixed point, inertial force, normal and shear contact forces and friction force are presented. The VC++ codes for the second‐ and third‐order cases have been developed, and they have been applied to examples of 3‐D beams, bending under various loading conditions applied at the end and to an example of discontinuous problem. Results of modeling, are well in agreement with theoretical solutions. In contrast, the results calculated for the same model, using original first‐order 3‐D DDA are far from the theoretical solutions. Copyright © 2009 John Wiley & Sons, Ltd.
On the application of a spatial chaotic model for detecting landcover changes in synthetic aperture radar images

We present a change detection method for terrain covers from multi-temporal SAR images based on a spatial chaotic model which is known to adequately characterize the coherent process of SAR imaging. The major problem of SAR change detection rises from both the presence of speckle noise and the pixel mis-registration that are commonly seen in the remote sensing image. By means of chaotic model, we first transform the images to fractal domain and then perform the CFAR detection. Simulated tests are conducted to quantitatively evaluate the impacts of these two major error sources on detection rate. Results from satellite SAR for landcover change detection clearly show that the proposed algorithm not only the speckle noise can be effectively suppressed without scarifying the spatial resolution; the excruciating mis-registration error was taken into account and removed.
Numerical studies of hyperplasticity with single, multiple and a continuous field of yield surfaces

The development of a new constitutive model would normally require a new procedure to be established for derivation of the incremental response. However, for models generated within the framework of hyperplasticity (using single, multiple or continuous yield surfaces), this derivation can be carried out using standard procedures. In this paper we present first the unified incremental response for a model using a single internal variable for general loading conditions. Next, we develop and explore three different numerical techniques for implementation of this procedure. One of the approaches, which seems superior, is extended to the multi‐surface hyperplastic formulation. Finally, to allow integration of continuous hyperplastic models within the same multi‐surface hyperplastic setting, the issue of discretization of the continuous field of yield surfaces is addressed. Copyright © 2003 John Wiley & Sons, Ltd.
The Use of Global and Mesoscale Meteorological Model Data to Predict the Transport and Dispersion of Tracer Plumes over Washington, D.C.

Abstract The data from a yearlong tracer dispersion experiment over Washington, D.C., in 1984 were used to evaluate Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) dispersion model calculations using coarse global meteorological reanalysis data [NCEP–NCAR and 40-Yr ECMWF Re-Analysis (ERA-40)] and calculations using meteorological data fields created by running a high-resolution meteorological model [fifth-generation Pennsylvania State University–NCAR Mesoscale Model (MM5)]. None of the meteorological models were optimized for urban environments. The dispersion calculation using the ERA-40 data showed better performance than those using the NCEP–NCAR data and comparable performance to those using MM5 data fields. Calculations with MM5 data that used shorter-period forecasts were superior to calculations that used forecast data that extended beyond 24 h. Daytime dispersion model calculations using the MM5 data showed an underprediction bias not evident in calculations using the ERA-40 data.
Continuum model for quadratic memories

Quadratic Hadamard memories are investigated with the continuum model by means of theory and numerical computation. The memory serves as the second stage in a selective reflexive memory (SRM). The first stage of the SRM transforms the bipolar input into a linear combination of Hadamard vectors. The second stage selects from this linear combination the dominant Hadamard vector. Upon return of this vector to the front stage, a backstroke produces the stored vector which is labeled by the Hadamard vector selected. It is found that any SRM of dimension N that is a power of 2 performs perfect associative recall of up to N stored bipolar vectors for a certain choice of gain and the coupling between the two stages. This theoretical result is confirmed by numerical computations for N=8 and 16. <<ETX>>
Decentralized routing controller design using overlapping decompositions

The use of overlapping decompositions in designing routing controllers for large-scale networks is considered and a decentralized dynamic routing controller design strategy is proposed. The strategy is based on the overlapping decompositions method and can be used for large-scale networks which have more than two overlapping subnetworks and/or have more than one node in the overlapping part. The controller obtained by the proposed strategy is decentralized in the sense that all on-line computations can be done locally at the individual nodes without any information transfer from the other nodes. The controller satisfies all the routing control constraints and it avoids any looping. The controller also clears the queues in finite time in the absence of external arrivals and it keeps the queue lengths bounded in the presence of external arrival rates which do not exceed a certain maximum rate. In order to illustrate the proposed controller's performance, the controller is applied to an example network and s.
Performance and pulse shortening effects in a 200-kV PASOTRON/sup TM/ HPM source

The PASOTRON/sup TM/ is a unique, high-power microwave source that uses a long-pulse (/spl les/100 /spl mu/s) plasma-cathode electron-gun and plasma-filled slow-wave structure (SWS) to produce high-energy microwave pulses. The device utilizes no externally-produced magnetic fields; relying on a beam-generated plasma channel in the SWS to transport the beam. Peak powers of up to 5 MW were previously reported in C-band using a rippled-wall waveguide SWS. Scaling experiments indicated that increasing the beam voltage above the 90 kV C-band operation produces significantly higher peak powers. We report results from an L-band PASOTRON/sup TM/ BWO designed to operate at 200 kV. The plasma-cathode E-gun built for this device generated beams with voltages of up to 225 kV and currents in excess of 1 kA for pulse lengths of up to 200 /spl mu/s. The L-band PASOTRON/sup TM/ BWO produced 10-20 MW of peak power in the TM/sub 01/ mode, which was converted in the output to a TE/sub 11/ mode with fixed polarization. The PASOTRON/sup TM/ also directly produced TE-mode radiation in the 5-10 MW power range with a rotating output polarization, the rate of which can be controlled externally. The peak power and poise width was limited by the stability of the plasma channel at high peak powers and excessive plasma generation in the SWS during the long pulse length.
Priority wavelet packet decomposition and representation

Wavelet packets (WPs) offer a general framework for representing an arbitrary signal efficiently. But the associated computational cost of finding an optimal WP basis is quite high. To address this problem, the authors introduce, first, a signal-conditioning-based spectral density-driven wavelet transform (SDDWT). The structure of implementing SDDWT is similar to that of discrete wavelet transform (DWT) but it provides better approximation performance than that offered by DWT for a dominantly band-pass signal, including low pass. Then, for arbitrary signal, a generalisation of SDDWT, which the authors call as spectral density-driven wavelet packet (SDDWP) transform is introduced. The resultant bands have certain priority according to their ability to reduce the reconstruction error. The SDDWP can be considered a near-optimal WP basis but is also amenable to fast optimal WP basis search, at much reduced computational cost. Also, it not only provides improved approximation performance but in this case the complexity of implementing the transformation can be controlled. A side effect of the proposed transformation is the computation of signal-conditioning information, for which an efficient algorithm is provided. Simulations results have shown improved approximation performance.
Dipole fluctuations and the duration of geomagnetic polarity transitions

Geomagnetic polarity transitions are often accompanied by a decrease in magnetic intensity. The time required to reestablish the magnetic intensity after a transition is usually longer than the duration based on magnetic direction. Analysis of the paleomagnetic axial dipole moment from the PADM2M model shows a return to the time‐averaged intensity after 42 kyr. A shorter time is required to recover a fraction of the time‐averaged moment, but the correspondence between recovery time and fraction of recovery is nonlinear. Predictions of a stochastic model reproduce the general trends in recovery time and suggest that fluctuations in dipole generation increase substantially during polarity transitions relative to times of stable polarity. These large fluctuations could reflect larger convective velocities in the core or represent a change in the efficiency of dipole generation. In either case, large fluctuations during polarity transitions can flip the sign of the axial dipole field several times before a polarity transition is completed.