Miracle-dz/UniFAR-FTUs huggingface dataset:
Low complexity LSF quantization for wideband speech coding

State-of-the-art narrowband speech coders operating from 4 to 16 kbit/s are mostly based on the code-excited linear predictive (CELP) model. They achieve a good synthesis quality usually at the expense of a high coding complexity. For example, in the 8 kbit/s G.729 coder the innovation codebook search is responsible for approximately half the total coder complexity, the latter being close to 20 MIPS in fixed-point DSP implementation. Less known is the relative part of spectral quantization, which is around 8% of the total complexity. CELP coders are still relevant for wideband speech coding but their complexity is greater than in the narrowband case, which becomes critical for real-time implementations. We propose in this article a two-stage algebraic-stochastic line spectral frequency (LSF) quantization scheme. It combines the strengths of algebraic and stochastic techniques, namely low computation and storage cost and good performance. The generalized Lloyd-Max algorithm is adapted for optimizing lattice codebooks obtained by spherical truncation. Simulations with a Gaussian source show that the quantization method exhibits good quality/complexity tradeoffs. Several stochastic-algebraic LSF quantizers are derived and compared to a more conventional technique.
A POD Study of an Impinging Jet Flowfield

Snapshot Proper Orthogonal Decomposition (POD) has been applied to reveal the dominant flow structures of an impinging jet flow field. PIV datasets of 200 snapshots were used for the POD analysis. The planar PIV measurements covered the free jet, stagnation and wall jet regions. The jet issued from a long pipe, 112 diameter, D, which ensured fully developed turbulent flow conditions at the outlet. The Reynolds number based on jet mean exit velocity was 16,000 and the pipe-to-plate separation, H, varied between 1D and 8D. The five most energetic modes were identified and found to contain 19–32% of the total turbulent energy. The energetic low modes were most pronounced for H/D = 8. The spatial topology was investigated by using velocity and vorticity fields of the mean flow and first five POD modes. For H/D = 8, the dominant flow structures were vortex tubes along the periphery of the jet. However, for H/D = 1, vortices along the impingement wall, outside of the stagnation region, were most prominent. The formation of vortices and their interaction with the impingement wall enhances local momentum transfer rates and could explain the secondary Nusselt number peak observed only at low separation distances.Copyright © 2009 by ASME
Lambert emitters: a simple Monte-Carlo approach to optical diffusers

The lambertian behaviour of an optical diffuser is analyzed. A simple model, coupled to a Monte-Carlo approach, has been used to study the angular dependence of the reflected rays and obtain some performance parameters of the diffuser. The origin of the Lambertian distribution of the reflected rays, as well as of some deviation from it, are discussed in terms of that model.
Characterization of ultraviolet femtosecond pulse propagation in aluminum-coated capillary fibers

We demonstrate that hollow core fibers with aluminum-coated bores of ϕ=0.7mm and ϕ=1.0mm are well suited for guiding high-power ultraviolet femtosecond pulses. We consider 1-m-long fibers in two geometries: straight and bent with a 30-cm radius of curvature. The straight fibers transmit approximately 60% of the power at 200nm and 85% at 266nm, while the corresponding numbers for the bent fibers are 25% and 35%. The duration of the femtosecond pulses increases by 10% and 50% per meter at 200 and 266nm, respectively. The broadening increases to a factor of two when the fiber is bent. The maximum transmitted pulse energy at 266nm is 100μJ corresponding to 0.5GW or an intensity of 1011W∕cm2. However, this value is limited only by the 266nm pulse generation and is expected to go even higher. The applicability of the powerful femtosecond pulses from the fiber is demonstrated by an experiment in which water is ionized by two-photon absorption. This experiment indicates the potential of using aluminized hollow co.
PHASE TRANSITIONS IN THE HUMAN BRAIN: SPATIAL MODE DYNAMICS

Pattern formation and switching between self-organized states are often associated with instabilities in open, nonequilibrium systems. We describe an experiment which shows that systematically changing a control parameter induces qualitative changes in sensorimotor coordination and brain activity, as registered by a 37-SQUID (Superconducting Quantum Interference Device) array. Near the instability point, predicted features of nonequilibrium phase transitions (critical slowing down, fluctuation enhancement) are observed in both the psychophysical data and the brain signals obtained from single SQUID sensors. Further analysis reveals that activity from the entire array displays spatial patterns evolving in time. Such spatiotemporal patterns are characterized by the dynamics of only a few coherent spatial modes.
Energy dissipation in tapping-mode atomic force microscopy

A method is presented to measure the energy dissipated by the tip–sample interaction in tapping-mode atomic force microscopy (AFM). The results show that if the amplitude of the cantilever is held constant, the sine of the phase angle of the driven vibration is then proportional to changes in the tip–sample energy dissipation. This means that images of the cantilever phase in tapping-mode AFM are closely related to maps of dissipation. The maximum dissipation observed for a 4 N/m cantilever with an initial amplitude of 25 nm tapping on a hard substrate at 74 kHz is about 0.3 pW.
Perpendicular magnetic anisotropy induced by a cap layer in ultrathin MgO/CoFeB/Nb

Perpendicular magnetic anisotropy has been observed in MgO/CoFeB/Ta but not in MgO/CoFeB/Ru, indicating that the metal cap layer is crucial. In this study, we grew MgO/CoFeB (1.2 nm)/Nb (1–2.5 nm) by sputtering and found that the magnetic anisotropy depends upon the Na thickness. The easy axis is in-plane when x = 1 nm but changes to perpendicular when x ≥ 1.2, and a transition from in-plane to perpendicular is observed at x = 1.1 nm. Perpendicular magnetic anisotropy gradually decays as the x increases, showing that it only exists in a small window of the cap Nb layer within ∼2 nm.
Periodic Orbits and Classical Quantization Conditions

The relation between the solutions of the time‐independent Schrodinger equation and the periodic orbits of the corresponding classical system is examined in the case where neither can be found by the separation of variables. If the quasiclassical approximation for the Green's function is integrated over the coordinates, a response function for the system is obtained which depends only on the energy and whose singularities give the approximate eigenvalues of the energy. This response function is written as a sum over all periodic orbits where each term has a phase factor containing the action integral and the number of conjugate points, as well as an amplitude factor containing the period and the stability exponent of the orbit. In terms of the approximate density of states per unit interval of energy, each stable periodic orbit is shown to yield a series of δ functions whose locations are given by a simple quantum condition: The action integral differs from an integer multiple of h by half the stability a.
The near-infrared continuum emission of visual reflection nebulae

In the past, reflection nebulae have provided an astrophysical laboratory well suited for the study of the reflection properties of interstellar dust grains at visual and ultraviolet wavelengths. The present investigation is concerned with observations which were begun with the objective to extend to near-infrared wavelengths the study of grains in reflection. Observations of three classical visual reflection nebulae were conducted in the wavelength range from 1.25 to 2.2 microns, taking into account NGC 7023, 2023, and 2068. All three nebulae were found to have similar near-infrared colors, despite widely different colors of their illuminating stars. The brightness level shown by two of the nebulae at 2.2 microns was too high to be easily accounted for on the basis of reflected light. Attention is given to a wide variety of possible emission mechanisms.
Statistical inference under order restrictions : the theory and application of isotonic regression

Abstract : ;Contents: Isotonic regression; Estimation under order restrictions; Testing the equality of ordered means--likelihood ratio tests in the normal case; Testing the equality of ordered means--extensions and generalizations; Estimation of distributions; Isotonic tests for goodness of fit; Conditional expectation given a sigma-lattice.
A statistical model for the temporal pattern of individual automated teller machine withdrawals

Summary. Models of consumer behaviour that are based purely on empirical relationships in data can perform well in the short term but often degrade rapidly with changing circumstances. Superior longer‐term performance can sometimes be attained by developing models for the deeper processes underlying the consumer behaviour. We develop a random‐effects point process model for automated teller machine withdrawals. Estimation, prediction and computational issues are discussed. The model may be used to predict behaviour for an individual and to assess when state changes in individual behaviour have occurred and as a description of behaviour for a portfolio of accounts.
Statistical Problems in Ancient Numismatics

In antiquity coins were struck by placing a heated coin blank between two dies and hitting the upper die with a heavy blow of a hammer. When a die wore off, a new one was engraved. So dies intended to be the same show small differences that may be observed on extant coins as “the varieties”. Numismatists collect statistics of die varieties in as large a sample as possible of extant coins of a single issue they can find to study. From these statistics they want to estimate the number of dies used in producing the coin issue. To do this they need a parametric stochastic model describing how coins survive and become part of the sample. Several models are tried and tested against the data of two large samples, one of them new. (Few large samples exist). Estimators are reviewed and some related statistical problems studied.
Virtual Field and Internal Structure of Half-Dressed Extended Particles

A new method is proposed to investigate the internal geometrical structure of an extended particle surrounded by an incomplete virtual dressing field. This method involves analysing the time-dependent virtual field at large distances from the particle, without any direct interaction with the latter. As an example, the pulselike, time-dependent virtual field of an extended QED source is investigated using a model which has a well-known counterpart in meson theory. In the framework of nonrelativistic QED it is shown that, contrary to the case of a point source, the pulse has finite width and height. For the case of a spherically symmetric source, it is explicitly shown that the width and shape of the pulse at distance r from the particle depend on the parameters determining the space structure of the source. It is concluded that the study of the field of half-dressed particles may provide a new method to investigate their internal structure.
Boundary value controllability and observability problems for the wave and heat equation

Abstract In this paper, we study controllability and observability problems for the wave and heat equation in a spherical region in Rn, where the control enters in the mixed boundary condition. In the main result, we show that all “finite energy” initial states (i.e. (ω0, ν0) ∈ H1(Ω) × L2 (Ω)) can be steered to zero at time T, using a control f ∈ L2 (∂Ω × [0, T]), provided T > 2. On this basis, we use the duality principle to investigate initial observability for the wave equation. Applying the Fourier transform technique, we obtain controllability and observability results for the heat equation.
Dust in the Narrow-Line Region of Active Galactic Nuclei

Observations of active galactic nuclei (AGNs) show the presence of a cloud system with two well-separated regions of line emission, the narrow-line region (NLR) and the broad-line region (BLR). There are several unexplained features of the system. First, there is an apparent gap between the BLR and the NLR with almost no line emission. Second, the covering factor of the NLR clouds, as inferred from photoionization models, is an order of magnitude smaller than the covering factor of the BLR, but the observed infrared continuum and new high-resolution HST images suggest a much larger covering factor. Finally the BLR size scales with the source luminosity in a way which is not understood
High minority carrier lifetime in phosphorus-gettered multicrystalline silicon

The electronic quality of multicrystalline material produced by directional solidification has been evaluated by means of photoconductance techniques. Very high minority carrier lifetimes, in the vicinity of 200 μs, have been measured in p-type 1.5 Ω cm material that had received a phosphorus diffusion gettering treatment. The measurements correspond to an effective lifetime averaged over an area of 3 cm2 that includes several grain boundaries and reflects the combined bulk, grain boundary and surface recombination mechanisms. The high lifetime (15 μs) also obtained in low resistivity 0.2 Ω cm wafers has allowed the fabrication of solar cells with an open-circuit voltage of 657 mV (AM1.5 G, 100 mW/cm2, 25 °C), probably the highest ever reported for multicrystalline silicon.
Transient Recombination of Excess Carriers in Semiconductors

The recombination equations for a system containing an arbitrary number of Shockley-Read recombination centers are formulated. Transient solutions are obtained for the decay following the injection of a pulse of carriers into a system containing one or two centers. The specific cases considered include (1) the simple one-center case, which enables us to discuss (a) the situation for a large injection of carriers, (b) recombination through donors in $n$-type or acceptors in $p$-type material, and (c) recombination through centers in the presence of direct recombination; (2) the case of a recombination center with a temporary trap, and (3) the case of two recombination centers.
Bayesian Regularisation in Structured Additive Regression Models for Survival Data

During recent years, penalized likelihood approaches have attracted a lot of interest both in the area of semiparametric regression and for the regularization of high-dimensional regression models. In this paper, we introduce a Bayesian formulation that allows to combine both aspects into a joint regression model with a focus on hazard regression for survival times. While Bayesian penalized splines form the basis for estimating nonparametric and flexible time-varying effects, regularization of high-dimensional covariate vectors is based on scale mixture of normals priors. This class of priors allows to keep a (conditional) Gaussian prior for regression coefficients on the predictor stage of the model but introduces suitable mixture distributions for the Gaussian variance to achieve regularization. This scale mixture property allows to device general and adaptive Markov chain Monte Carlo simulation algorithms for fitting a variety of hazard regression models. In particular, unifying algorithms based on iteratively weighted least squares proposals can be employed both for regularization and penalized semiparametric function estimation. Since sampling based estimates do no longer have the variable selection property well-known for the Lasso in frequentist analyses, we additionally consider spike and slab priors that introduce a further mixing stage that allows to separate between influential and redundant parameters. We demonstrate the different shrinkage properties with three simulation settings and apply the methods to the PBC Liver dataset.
Solar cycle invariance in solar wind proton temperature relationships

The relationships between solar wind proton temperature and velocity and between temperature and momentum flux density at 1 AU are examined using National Space Science Data Center IMP 8 solar wind data obtained from late 1984 to early 1985. These relationships are compared with similar ones obtained from a variety of solar wind data spanning 14 years, from 1966 to 1980. It is found that these relationships, particularly the one between temperature and velocity, are very stable over the solar cycles from which these data were drawn. This suggests that the basic physical processes which accelerate and heat the solar wind have remained unchanged for the last 20 years. Over this same period, the energy, momentum, and mass fluxes produced by the Sun to generate the solar wind varied by about 60%. A qualitative explanation of these results is given in the context of a model for solar wind generation that includes significant postsonic momentum and energy deposition and assumes that solar wind protons are heated by magnetohydrodynamic waves of solar origin.
Numerical solution of transient temperature for pulsed heating in a single spherical particle model

Photothermal technique provides a convenient means for detecting the change in pulse‐induced thermal radiation emission from a single spherical particle. The change in the emitted blackbody radiation is determined by the change in the surface temperature of the particle which in turn can be derived from heat conduction equation. Numerical solution to the heat conduction equation for a single spherical particle model on thermally bad conducting samples is derived and compared with a relatively simple analytical solution. Some results for particles of interest are discussed.
Defining and identifying cograph communities in complex networks

Community or module detection is a fundamental problem in complex networks. Most of the traditional algorithms available focus only on vertices in a subgraph that are densely connected among themselves while being loosely connected to the vertices outside the subgraph, ignoring the topological structure of the community. However, in most cases one needs to make further analysis on the interior topological structure of communities to obtain various meaningful subgroups. We thus propose a novel community referred to as a cograph community, which has a well-understood structure. The well-understood structure of cographs and their corresponding cotree representation allows for an immediate identification of structurally-equivalent subgroups. We develop an algorithm called the Edge P4 centrality-based divisive algorithm (EPCA) to detect these cograph communities; this algorithm is efficient, free of parameters and independent of additional measures mainly due to the novel local edge P4 centrality measure. Further, we compare the EPCA with algorithms from the existing literature on synthetic, social and biological networks to show it has superior or competitive performance in accuracy. In addition to the computational advantages over other community-detection algorithms, the EPCA provides a simple means of discovering both dense and sparse subgroups based on structural equivalence or homogeneous roles which may otherwise go undetected by other algorithms which rely on edge density measures for finding subgroups.
Toward a Nonlinear Acoustic Analogy: Turbulence as a Source of Sound and Nonlinear Propagation

An acoustic analogy is proposed that directly includes nonlinear propagation effects. We examine the Lighthill acoustic analogy and replace the Green's function of the wave equation with numerical solutions of the generalized Burgers' equation. This is justified mathematically by using similar arguments that are the basis of the solution of the Lighthill acoustic analogy. This approach is superior to alternatives because propagation is accounted for directly from the source to the far-field observer instead of from an arbitrary intermediate point. Validation of a numerical solver for the generalized Burgers' equation is performed by comparing solutions with the Blackstock bridging function and measurement data. Most importantly, the mathematical relationship between the Navier- Stokes equations, the acoustic analogy that describes the source, and canonical nonlinear propagation equations is shown. Example predictions are presented for nonlinear propagation of jet mixing noise at the sideline angle
A large volume microwave plasma source

We report on the design, construction, and use of a large cavity microwave plasma source. The source is designed to provide a range of space‐plasma‐like conditions in the Naval Research Laboratory Space Physics Simulation Chamber. A new feature of the source design incorporates hard anodized aluminum as the internal cavity area surface and does not use the conventional quartz cavity liner which is prone to overheating and cracking with extended use. By placing a number of small plasma outlet holes around the surface of a 36.8 cm output plate, we are able to provide a fairly radially uniform plasma; by further surrounding the production region and exit with an axial pinch magnetic field we are able to extend this region of plasma uniformity further toward the chamber walls and cover a significant portion of the experimental area. The source provides plasmas with selectable densities between 104 and 108 cm−3 and electron temperatures vary from about 0.5 to 2.0 eV.
Interlayer phase correlation of the vortex system around the coupling transition in Bi 2 Sr 2 CaCu 2 O y containing columnar defects

The Josephson plasma resonance and dc magnetization were investigated in a high-T{sub c} cuprate Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub y} (Bi-2212) containing columnar defects in order to clarify the detailed bahavior in the reversible region around the coupling transition of pancake vortices. We point out that the coupling transition line which separates decoupled and well-coupled pancake vortices is a temperature independent horizontal line on the H-T plane. This result indicates that the coupling transition is a field-induced phenomenon. We find that the rapid reduction of the interlayer phase correlation and the enhancement of the in-plane critical current density take place simultaneously at B=B{sup {asterisk}}, which is just below the coupling transition field B{sub cp}. This phenomenon may be interpreted as the field-induced acceleration of the decoupling of pancake vortices in the reversible region of Bi-2212 with columnar defects. B{sub cp} was rather smaller than B{sub {phi}}. From transmission electron microscopy, we infer that the inhomogeneous distribution of columnar defects may be related to the coupling transition field B{sub cp}{approximately}B{sub {phi}(eff)}, which was rather smaller than B{sub {phi}}. {copyright} {ital 1999} {ital The American Physical Society}
High performing phase-based surface plasmon resonance sensing from metallic nanohole arrays

We show the spectral figure-of-merit (FOM) from nanohole arrays can be larger than 1900/RIU by phase-based surface plasmon resonance. By using temporal coupled mode theory, we find the p-s polarization phase jump is the sharpest when both the absorption and radiative decay rates of surface plasmon polaritons are matched, yielding an extremely small spectral differential phase linewidth and thus superior FOM. The result is supported by numerical simulation and experiment. As a demonstration, we show the phase detection outperforms the conventional spectral counterpart significantly by sensing the binding of bovine serum albumin antibodies under identical condition.