Miracle-dz/UniFAR-FTUs huggingface dataset:
Entropy Splitting and Numerical Dissipation

A rigorous stability estimate for arbitrary order of accuracy of spatial central difference schemes for initial boundary value problems of nonlinear symmetrizable systems of hyperbolic conservation laws was established recently by Olsson and Oliger (1994, “Energy and Maximum Norm Estimates for Nonlinear Conservation Laws”, RIACS Report, NASA Ames Research Center) and Olsson (1995, Math. Comput.64, 212) and was applied to the two-dimensional compressible Euler equations for a perfect gas by Gerritsen and Olsson (1996, J. Comput. Phys.129, 245) and Gerritsen (1996, “Designing an Efficient Solution Strategy for Fluid Flows, Ph.D. Thesis, Stanford). The basic building block in developing the stability estimate is a generalized energy approach based on a special splitting of the flux derivative via a convex entropy function and certain homogeneous properties. Due to some of the unique properties of the compressible Euler equations for a perfect gas, the splitting resulted in the sum of a conservative portion and a non-conservative portion of the flux derivative, hereafter referred to as the “entropy splitting. ” There are several potentially desirable attributes and side benefits of the entropy splitting for the compressible Euler equations that were not fully explored in Gerritsen and Olsson. This paper has several objectives. The first is to investigate the choice of the arbitrary parameter that determines the amount of splitting and its dependence on the type of physics of current interest to computational fluid dynamics. The second is to investigate in what manner the splitting affects the nonlinear stability of the central schemes for long time integrations of unsteady flows such as in nonlinear aeroacoustics and turbulence dynamics. If numerical dissipation indeed is needed to stabilize the central scheme, can the splitting help minimize the numerical dissipation compared to its un-split cousin? Extensive numerical study on the vortex preservation capab ility of the splitting in conjunction with central schemes for long time integrations will be presented. The third is to study the effect of the non-conservative proportion of splitting in obtaining the correct shock location for high speed complex shock-turbulence interactions. The fourth is to determine if this method can be extended to other physical equations of state and other evolutionary equation sets. If numerical dissipation is needed, the Yee, Sandham, and Djomehri (1999, J. Comput. Phys.150, 199) numerical dissipation is employed. The Yee et al. schemes fit in the Olsson and Oliger framework.
Temperature-dependent structure and electrical transport in liquid metals

A simple model has been considered to obtain the reversible temperature dependence of the static structure factors S(q) for liquid metals. The measured values of S(q) near the melting point have been utilised to obtain the same at elevated temperatures for Na, K, Mg, Zn, Al and Pb. The notion of Debye temperature in liquid metals has been discussed. The principal peak heights of S(q) computed at the melting temperature have also been discussed in the light of Verlet's freezing rule. The electrical resistivity and thermo-electric power of these metals have been computed as a function of temperature. The success and failure of the Ziman formula have been critically assessed.
How to Reduce an Unwritten Language to Writing: III. Phonetic Similarity, Suspicious Pairs, and Minimal Pairs

Phonetic analysis can be done with a short list of a few hundred words. First, carefully transcribe the list phonetically. Second, list the inventory of symbols. Third, tabulate the symbols by their articulatory position. Fourth, declare symbols in close articulatory proximity, that is, sounds of great phonetic similarity, as suspicious pairs. Finally, find two words with different meanings that are phonetically identical except for one member of a suspicious pair in each. Finding such a minimal pair implies that we have found a phoneme (writing symbol).
Allocation of losses in distribution systems with embedded generation

Deficiencies in present-day loss allocation practices are demonstrated using as an example the substitution method applied in England and Wales to evaluate the impact of embedded generation (EG) on losses. Two new loss allocation schemes are proposed; one based on the allocation of marginal losses and the other on the allocation of total losses. Loss allocation factors computed from the proposed schemes are specific to location and time of use. This is especially important for EG whose impact on losses varies in time and space. A notable feature of the proposed loss allocation coefficients is that they can be positive or negative and therefore can recognise the presence of counter-flows such as those due to the presence of EG. Application of the proposed loss allocation schemes is illustrated on a real network based 265-node generic distribution system model incorporating EG.
Development of a Mini Liquid Cooling System for High-Heat-Flux Electronic Devices

This study incorporated the authors’ previously published micro heat exchanger with a newly designed micro pump to develop a high-performance, mini size liquid cooling system. An integrated pump and cold-plate assembly was also developed for further reducing the overall size of the system. The test results show that the micro pump provides a higher maximum pressure head and maximum flow rate in comparing to the performance of the commercial products. The performance of the entire liquid cooling system is similar to that of the recently announced product. The present study shows an optimum combination of a slim cold plate and a high-pressure-head micro pump. It provides a comparable thermal resistance but much smaller size and therefore lower cost than most of the commercial liquid cooling systems.
Low-Density Photodissociation Regions

A theoretical parameter study of the temperature and chemical structure of photodissociation regions (PDRs) and their resultant spectrum is presented. The models, which solve for the chemical and thermal steady state of a one-dimensional slab exposed to an incident FUV flux, relate the observed line and continuum emission from these regions to physical parameters of interest. Intensities of numerous fine-structure lines, the molecular rotational transitions (C-12)O J = 1-0 and H2 0-0 S(0), and the dust continuum intensities at 60 and 100 microns are predicted, and the column density of FUV-pumped vibrationally excited H2 is estimated. 74 refs.
Shortwave radiation budget at the boundaries of the earth-atmosphere system derived from satellite data

The influence of cloudiness on the shortwave radiation budget at the top of the atmosphere, at the surface, and, as a residual, for the atmosphere is investigated for an area of +/- 60 degree(s) longitude and latitude. The data used is exclusively taken from satellite measurements. Calculations for the top of the atmosphere are based entirely on measurements of the Earth Radiation Budget Experiment (ERBE). For the solar radiation budget at the surface, the incoming solar radiation at the surface is derived from Meteosat data and the surface albedo is calculated from ERBE clear sky planetary albedo measurements by applying an atmospheric correction scheme. As results, maps of absorbed solar radiation for the total earth-atmosphere system, the surface, and for the atmosphere are presented. To infer the contribution of clouds, the concept of cloud radiative forcing is applied to these different data sets.
On the decomposition of the modified Kadomtsev–Petviashvili equation and explicit solutions

The (2+1)-dimensional modified Kadomtsev–Petviashvili equation is decomposed into two known (1+1)-dimensional soliton equations. A Darboux transformation of the two known (1+1)-dimensional soliton equations is derived with the help of a gauge transformation of the spectral problem. As an application, explicit solutions of the two (1+1)-dimensional soliton equations and two new explicit solutions of the (2+1)-dimensional modified Kadomtsev–Petviashvili equation are obtained.
ROTATIONAL VELOCITY DETERMINATIONS FOR 164 BE AND B STARS

Rotational velocities, v sin i, have been obtained for 96 Be and 68 normal B stars by measurements of the FWHM of the He I lambda-4471 line (for spectral types B0-B4.5) and Mg II lambda-4481 (for types B5-B9.5). The consistency of various published sources is examined.
IDENTIFICATION OF KINETIC ALFVÉN WAVE TURBULENCE IN THE SOLAR WIND

The nature of small-scale turbulent fluctuations in the solar wind is investigated using a comparison of Cluster magnetic and electric field measurements to predictions arising from models consisting of either kinetic Alfvén waves or whistler waves. The electric and magnetic field properties of these waves from linear theory are used to construct spacecraft-frame frequency spectra of (|δE|/|δB|)s/c and (|δB∥|/|δB|)s/c, allowing for a direct comparison to spacecraft data. The measured properties of the small-scale turbulent fluctuations, found to be inconsistent with the whistler wave model, agree well with the prediction of a spectrum of kinetic Alfvén waves with nearly perpendicular wavevectors.
Three-dimensional microfluidic liquid-core/liquid-cladding waveguide

This letter describes a three-dimensional liquid-core/liquid-cladding optical waveguide system. The core fluid was focused in the vertical direction by a transverse secondary flow (produced by a Dean vortex) and focused in the horizontal direction by two parallel sheath flows. The waveguide introduced less optical loss between the core fluid and the channel wall. Diffusion between the core fluid and the cladding fluid was reduced by high fluid velocities. The present system can be considered as a graded-index waveguide due to the diffusion effect. The width of the core fluid was manipulated by adjusting the sheath flow rates. Numerical simulations were conducted to support and interpret the experimental results.
Transport of edge-localized mode energy in a scrape-off layer in the presence of collisionless fast electrons

The transport of the energy delivered by an edge-localized mode (ELM) into the scrape-off layer (SOL) of a tokamak plasma is studied with particle-in-cell simulations. A simple one-dimensional model with a Monte-Carlo procedure for Coulomb collisions is used. The SOL is collisional before the ELM, but the mean-free-path length in the hot ELM plasma is longer than the connection length, such that fast electrons can travel directly from the midplane to the target plate. However, the sheath potential increases rapidly, and most of the energy is transported with a velocity of order of the ion sound speed if secondary electron emission (SEE) is absent or weak. In the case of strong SEE, though, a large fraction of the energy can be carried by fast electrons during the ELM pulse.
Gated IR imaging with 128 × 128 HgCdTe electron avalanche photodiode FPA

The next generation of IR sensor systems will include active imaging capabilities. One example of such a system is a gated-active/passive system. The gated-active/passive system promises long-range target detection and identification. A detector that is capable of both active and passive modes of operation opens up the possibility of a self-aligned system that uses a single focal plane. The detector would need to be sensitive in the 3-5 μm band for passive mode operation. In the active mode, the detector would need to be sensitive in eye-safe range, e.g. 1.55 μm, and have internal gain to achieve the required system sensitivity. The MWIR HgCdTe electron injection avalanche photodiode (e-APD) not only provides state-of-the-art 3-5 μm spectral sensitivity, but also high avalanche photodiode gain without minimal excess noise. Gains of greater than 1000 have been measured in MWIR e-APDs with a gain independent excess noise factor of 1.3. This paper reports the application of the mid-wave HgCdTe e-APD for near-IR gated-active/passive imaging. Specifically a 128x128 FPA composed of 40 μm pitch, 4.2 μm to 5 μm cutoff, APD detectors with a custom readout integrated circuit was designed, fabricated, and tested. Median gains as high as 946 at 11 V bias with noise equivalent inputs as low as 0.4 photon were measured at 80 K. A gated imaging demonstration system was designed and built using commercially available parts. High resolution gated imagery out to 9 km was obtained with this system that demonstrated predicted MTF, precision gating, and sub 10 photon sensitivity.
A Twisted AdjointL-Value of an Elliptic Modular Form

Abstract We shall show an explicit value of a twisted adjoint L -value L (1, Ad ( f )⊗ χ ) attached to f . Here f is a primitive elliptic cusp form of “Haupt”-type and χ a quadratic character. The calculation can be done by using the formula of L (1, Ad ( f )⊗ χ ) obtained by Hida. This value supports numerically a conjecture of Doi–Hida–Ishii [3].
Tunable resonant cavity enhanced detectors using vertically actuated MEMS mirrors

Highly sensitive photodetectors for the mid-infrared have recently been obtained by placing a photodiode inside a Fabry-Perot cavity (Arnold et al 2005 Appl. Phys. Lett. 87 141103). These resonant cavity enhanced detectors (RCED) are sensitive at the resonances which depend on the distance between the two mirrors of the cavity (Unlu and Strite 1995 J. Appl. Phys. 78 608). Displacing one of these mirrors then makes it possible to change the cavity length and thus select the detection wavelength. The design, simulation and fabrication of a MEMS mirror is discussed in detail and its integration with the counter mirror and the photodiode, both grown by molecular beam epitaxy, are presented. Results obtained with external mirrors moved by piezoactuation as well as first measurements of a complete tunable RCED using electrostatically driven vertically moving MEMS mirrors are presented. Such tunable detectors are of interest in thermographic and spectroscopic applications.
Vortex solitons under competing nonlocal cubic and local quintic nonlinearities

Vortex solitons in nonlinear media with competing nonlocal self-focusing cubic and local self-defocusing quintic nonlinearities are studied analytically and numerically. By using an approximate variational approach, we obtain bifurcated solutions of the vortex solitons with the upper (lower) branch carrying larger (smaller) power stemmed by the competing effect between cubic and quintic nonlinearities. Besides the better stability of vortex solitons due to the competing effect, similar to the dynamics of the vortex solitons in the media with single nonlocal cubic nonlinearity only, the vortex solitons located in the lower branch always split into multipole scalar solitons in the limit of weak nonlocality and propagate stably when the degree of nonlocality is sufficiently strong. On the other hand, the internal modes of the vortex solitons in the upper branch are always unstable, and will break up into rings or spots of particle clusters. The dynamics and the stability of the vortex solitons are numerically demonstrated with the split-step Fourier transform method.
Enhanced resonant magnetoelectric coupling in frequency-tunable composite multiferroic bimorph structures

We report on a giant tunable enhanced resonant magnetoelectric (ME) coupling in multiferroic magnetostrictive/piezoelectric composite bimorph structures. The approach uses a magnetic/electric field assisted stress-reconfigurable resonance to produce frequency tuning of up to 100%. The studies were performed by laser Doppler spectroscopy. We also show that this principle of a continuously tuned resonance might be used to improve sensitivity for ME magnetic sensors.
Stationary analysis of a fluid queue with input rate varying as an Ornstein-Uhlenbeck process

The stationary probability distribution of the content of a fluid queue with constant output rate and input rate varying as an Ornstein-Uhlenbeck process is studied. Markov properties provide the set of equations for the derivation of this distribution; the consideration of its Fourier transform leads to the study of a functional equation of integral type in the complex plane. This analysis is shown to relate to that of the connected Fokker-Planck equation. Results are discussed and compared to that of a similar fluid queueing model.This study was motivated by teletrafflc problems encountered in the multiplexing of video communications with variable activity rate.
Efficient tuning of linear multivariable controllers using iterative feedback tuning

Iterative feedback tuning is a direct tuning method using closed-loop experimental data. The method is based on numerical optimization and in each iteration an unbiased gradient estimate is used. Due to these unbiased gradient estimates, the method converges to a stationary point of the control criterion provided the closed loop signals remain bounded throughout the iterations. In this contribution, it is shown how such unbiased estimates can be obtained for multivariable linear time-invariant systems. Particular attention is given to the issue of keeping the experiment time to a minimum and several efficient algorithms are presented. It is shown that, for tuning an arbitrary linear time-invariant multivariable controller with nw inputs and nu outputs, 1+nuA—nw experiments are sufficient in each iteration of the algorithm. For disturbance rejection, an alternative algorithm is proposed which requires nu+nw experiments. As an illustration, the method is applied to a simulation model of a gas turbine engine.
On diagonal approximations to the extended Kalman filter for online training of Bayesian neural networks

We present two approaches to approximate online Bayesian inference for the parameters of DNNs. Both are based on diagonal Gaussian approximations and linearize the network at each step to ensure efficient computation. The first approach optimizes the exclusive KL, D KL ( q ∥ p ); this amounts to matching the marginal mean and precision of p and q . The second approach optimizes the inclusive KL, D KL ( q ∥ p ), which amounts to matching the marginal mean and variance of p and q . The latter approach turns out to be equivalent to the previously proposed “fully decoupled EKF” approach. We show experimentally that inclusive KL yields better results than exclusive KL, and both are more effective than one-pass SGD.
Unraveling the Effect of MgAl/CuO Nanothermite on the Characteristics and Thermo-Catalytic Decomposition of Nanoenergetic Formulation Based on Nanostructured Nitrocellulose and Hydrazinium Nitro-Triazolone

The present study aims to develop new energetic composites containing nanostructured nitrocellulose (NNC) or nitrated cellulose (NC), hydrazinium nitro triazolone (HNTO), and MgAl-CuO nanothermite. The prepared energetic formulations (NC/HNTO/MgAl-CuO and NNC/HNTO/MgAl-CuO) were analyzed using various analytical techniques, such as Fourier-transform infrared (FTIR), scanning electron microscopy (SEM), thermogravimetry (TGA), and differential scanning calorimetry (DSC). The outstanding catalytic impact of MgAl-CuO on the thermal behavior of the developed energetic composites was elucidated by kinetic modeling, applied to the DSC data using isoconversional kinetic methods, for which a considerable drop in the activation energy was acquired for the prepared formulations, highlighting the catalytic influence of the introduced MgAl-CuO nanothermite. Overall, the obtained findings demonstrated that the newly elaborated NC/HNTO/MgAl-CuO and NNC/HNTO/MgAl-CuO composites could serve as promising candidates for application in the next generation of composite explosives and high-performance propellants.
How Dim Could Accreting Black Holes Be?

Recent hydrodynamical simulations of radiatively inefficient black hole accretion flows with low viscosity have demonstrated that these flows differ significantly from those described by an advection-dominated model. The black hole flows are advection-dominated only in their inner parts but convectively dominated at radii R ≳ 102RG. In such flows, the radiative output comes mostly from the convection part, and the radiative efficiency is independent of accretion rate and equals ϵBH ≃ 10-3. This value gives a limit for how dim an accreting black hole could be. It agrees with recent Chandra observations, which indicate that accreting black holes in low-mass X-ray binaries are dimmer by a factor of about 100 than neutron stars accreting with the same accretion rates.
Algebraic multigrid and incompressible fluid flow

This paper is concerned with the development of algebraic multigrid (AMG) solution methods for the coupled vector–scalar fields of incompressible fluid flow. It addresses in particular the problems of unstable smoothing and of maintaining good vector–scalar coupling in the AMG coarse‐grid approximations. Two different approaches have been adopted. The first is a direct approach based on a second‐order discrete‐difference formulation in primitive variables. Here smoothing is stabilized using a minimum residual control harness and velocity–pressure coupling is maintained by employing a special interpolation during the construction of the inter‐grid transfer operators. The second is an indirect approach that avoids the coupling problem altogether by using a fourth‐order discrete‐difference formulation in a single scalar‐field variable, primitive variables being recovered in post‐processing steps. In both approaches the discrete‐difference equations are for the steady‐state limit (infinite time step) with a fully implicit treatment of advection based on central differencing using uniform and non‐uniform unstructured meshes. They are solved by Picard iteration, the AMG solvers being used repeatedly for each linear approximation.
Stochastic relaxations and em algorithms for markov random fields

This paper presents a simulation study of block (one line or two lines of pixels) updating for Markov random fields. Point and line relaxation methods are compared. Some pseudo-likelihoods, based on the conditional density of a block of pixels, are used together with modified EM algorithms to estimate parameters from noisy images.
Direct measurement of the electric‐field‐dependent absorption coefficient in GaAs/AlGaAs multiple quantum wells

Although large changes in the absorption coefficient of multiple quantum wells (MQW’s) with applied voltage have been reported, no accurate measurement of the minimum absorption coefficient, which determines the absorption component of the device insertion loss, has been reported. Using a new measurement technique, we measure this minimum absorption coefficient, and determine that, for a device with a 10:1 on/off ratio and a 7 dB insertion loss, absorption contributes 2.2 dB of the insertion loss. We are able to predict absorption losses of future devices and show that, by a slight change in operating wavelength, the absorption loss can be greatly reduced.
Semiparametric transformation models for the case-cohort study

A general class of semiparametric transformation models is studied for analysing survival data from the case-cohort design, which was introduced by Prentice (1986). Weighted estimating equations are proposed for simultaneous estimation of the regression parameters and the transformation function. It is shown that the resulting regression estimators are asymptotically normal, with variance-covariance matrix that has a closed form and can be consistently estimated by the usual plug-in method. Simulation studies show that the proposed approach is appropriate for practical use. An application to a case-cohort dataset from the Atherosclerosis Risk in Communities study is also given to illustrate the methodology. Copyright 2006, Oxford University Press.