Miracle-dz/UniFAR-FTUs huggingface dataset:
Automatic feature-finding for time-frequency distributions

Given the detailed time and frequency resolution of time-frequency distributions, trainable automatic classifiers can easily be overwhelmed by the complexity of this input representation. This problem becomes even more severe as more advanced and higher resolution time-frequency distributions come into use. Our research is directed to making a better match to automatic classification by automatically finding a set of lower-dimensionality features within time-frequency distributions. We show the efficacy and generality of this approach to a wide variety of time-frequency distributions. A connection is also made to hidden Markov model-based classification and a comparative study is shown for this type of classifier for conventional and more advanced proper time-frequency distributions. We conclude that, when used within the context of hidden Markov model-based classification, the proper time-frequency distribution offers the best ability to reserve classes representing changes in constituents of short acoustic transients. We have developed a vector quantization technique which is a modified version of Kohonen's (1990) self-organizing feature map and then applied it to conventional time-frequency representations (the magnitude of the short-time Fourier transform), more advanced time-frequency representations (the minimum cross-entropy (MCE) proper and positive distribution), and to a proper-distribution derived measure.
Quantification of trap densities at dielectric/III-V semiconductor interfaces

High-frequency capacitance-voltage curves for capacitors with high-k gate dielectrics and III–V semiconductor channels are modeled. The model takes into account the low conduction band density of states, the nonparabolicity of the Γ valley, and the population of higher lying conduction band valleys. The model is used to determine interface trap densities (Dit) and band bending of HfO2/In0.53Ga0. 47As interfaces with different Dit and with pinned and unpinned Fermi levels, respectively. Potential sources of errors in extracting Dit are discussed and criteria that establish unpinned interfaces are developed.
A Simplified Method for the Automatic Alignment of Images Affected by Random Noise

A simple method is described for the automatic alignment and averaging of images by computer. The method is based on the use of the cross-correlation function of the projections of the images on two axes. The results presented are obtained from synthetic images generated by computer on which a white noise of uniform distribution is added. These results are discussed, as is the possibility of improving the reliability of the alignment among the different images by comparing each one with all the others. This is possible because of the short calculation time needed for the alignment of the images when using the projections.
Stability of shear flow of stratified fluids with fine dust

The linear stability of plane parallel shear flows of a stably stratified incompressible fluid laden with uniformly distributed fine dust particles is studied. It is shown that the Miles criterion for stability, the Rayleigh–Synge criterion for instability, and Howard’s semicircle theorem can be extended under the assumptions that the mass concentration is very small and that the relaxation time of the dust particles is very much less than the time scale characterizing the basic flow. The effect of fine dust is found to increase the region of instability. In addition, a semi‐ellipse criterion for instability has been given as an improvement over Howard’s semicircle criterion.
Polarization-entangled Photons and Quantum Dense Coding

A down-conversion source of truly polarization-entangled photons has been developed [1], much brighter and more stable than all previous sources. In type-II phase-matching, the correlated photons are emitted with orthogonal polarizations. In contrast to the more familiar case of type-I phase matching, the cones of the emitted light are not concentric with the pump beam direction. Instead, the cone of photons that are extraordinary-polarized inside the birefringent nonlinear crystal (BBO, in our experiments) lies predominantly between the pump and the crystal optic axis, while the cone of the ordinary-polarized photons lies opposite (see Fig 1a). As a result, if the crystal is tilted slightly away from the collinear condition (where the two cones are tangent exactly along the pump beam direction), there arise two directions in which the photons belong to both the ordinary and the extraordinary cones (see Fig 1b).
Speeding up the computations of the minimum singular value of the load flow Jacobian matrix

The use of the minimum singular value (MSV) of the load flow Jacobian has been proposed as a security index for monitoring how close the operating condition of a power system is to a voltage instability. However, direct computation of singular value decomposition (SVD) is a very time consuming task. P.A. Lof et al. (see IEEE Trans. on Power Systems, vol.7, no.1, p.54-64, 1992) report on an elegant and an efficient algorithm for the computation of the MSV of the load flow Jacobian matrix (LFJM). This algorithm greatly reduces the time required for the computation of the MSV. In this letter, a new starting condition that reduces the computation time for the iterative process described by Lof et al. is proposed.
Magneto-optical properties of Heusler compounds from a first-principles approach

Accurate first principles calculations were performed to predict the optical and magneto-optical properties of a large set of Heusler compounds. The optical properties are explained in terms of relevant transitions from the underlying band-structure, suggesting that the joint density of states plays a role in shaping the optical spectra. As for the magneto-optical properties, our results show that most of the Heusler compounds have peaks in the Kerr rotations of the order of 0.5°, typical for 3d-based materials. The Kerr spectra are rather similar for all considered Heuslers, consistent with their overall comparable band-structure; the peaks in the Kerr angles were traced back to their optical versus magneto-optical contributions. This careful ab initio analysis is extremely helpful in view of engineering the Kerr rotation for technological purposes.
Design examples of diffraction-limited catadioptric objectives

The paper relates to different inventions, comprising three diffraction-limited catadioptric designs. All the systems use only spherical shaped surfaces and are designed from one kind of optical material only. In the examples the glass BK7 from the Schott-catalogue was used. The first example gives a three element design reaching equal performance as a Schmidt camera but with only 25 percent of its length. Additionally the field is flat and conveniently located behind the system. The second example is designed to reduce the central obstruction. It's somewhat based on the principle of the Houghton-camera. For a f-number 4 system with 1000 millimeters focal length it gives outstanding image quality at a 5 degree's field--even capable for diffraction-limited visual use. For reduced f-number 5,6 the image is diffraction-limited at the whole field. In terms of color correction it outperforms every Schmidt-Cassegrain or apochromatic triplet of even arbitrarily more reduced light gathering power. The third example is the equivalent for the so-called Wynne corrector triplet that corrects the aberrations of a parabolical mirror. But the invented corrector corrects additionally the spherical aberration of a spherical mirror. The corrector is able to correct all third order aberrations without introducing longitudinal and lateral color.
Overview of the CALIPSO Mission and CALIOP Data Processing Algorithms

Abstract The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is a two-wavelength polarization lidar that performs global profiling of aerosols and clouds in the troposphere and lower stratosphere. CALIOP is the primary instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite, which has flown in formation with the NASA A-train constellation of satellites since May 2006. The global, multiyear dataset obtained from CALIOP provides a new view of the earth’s atmosphere and will lead to an improved understanding of the role of aerosols and clouds in the climate system. A suite of algorithms has been developed to identify aerosol and cloud layers and to retrieve a variety of optical and microphysical properties. CALIOP represents a significant advance over previous space lidars, and the algorithms that have been developed have many innovative aspects to take advantage of its capabilities. This paper provides a brief overview of the CALIPSO mission, the CA.
Measurement optimization with sensitivity criteria for distributed parameter systems

We consider the problem of optimally designing sensors for observation of a class of distributed parameter systems. The design of sensors concerns the choice of measurement conditions so that the information provided by measurements is maximal. This problem has been posed as a deterministic optimal control problem for a system equation of the Riccati type which governs a filter covariance. In the present study we introduce a functional called a sensitivity criterion by extending the Fisher information matrix to function spaces. It is shown that maximizing this criterion leads to a suboptimal solution of the sensor design problem associated with an infinite-dimensional state estimation problem. The existence theorem for a type of measurement control problem is proved and some numerical results are presented.
Adaptive power control of cellular CDMA systems via the optimal predictive model

For direct sequence code division multiple access cellular radio systems, an autoregressive moving average model with auxiliary input (ARMAX) process is given to model the effects of round-trip delay, channel fading, and interferences (in-cell multiple access interference and out-of-cell interference) upon the power control system. According to the predictive model corresponding to the ARMAX model, a predictive adaptive power control scheme is proposed to compensate for the time delay and reduce the affects of channel fading and interference, thus achieving optimal tracking, in the sense of minimum mean square error control error, of the desired signal-to-interference-plus-noise ratio. Due to the optimal adaptive prediction scheme, the proposed adaptive power control method does not require the statistics of fading and interferences. Several simulation results are given to confirm the performance of the proposed method.
Optimal design of IIR digital filters with robust stability using conic quadratic programming

In this paper, minimax design of infinite-impulse-response (IIR) filters with prescribed stability margin is formulated as a conic quadratic programming (CQP) problem. CQP is known as a class of well-structured convex programming problems for which efficient interior-point solvers are available. By considering factorized denominators, the proposed formulation incorporates a set of linear constraints that are sufficient and near necessary for the IIR filter to have a prescribed stability margin. Also included in the formulation is a second-order cone condition on the magnitude of each update that ensures the validity of a key linear approximation used in the design and eliminates a line-search step. Collectively, these features lead to improved designs relative to several established methods.
Confidence limits for small numbers of events in astrophysical data

The calculation of limits for small numbers of astronomical counts is based on standard equations derived from Poisson and binomial statistics; although the equations are straightforward, their direct use is cumbersome and involves both table-interpolations and several mathematical operations. Convenient tables and approximate formulae are here presented for confidence limits which are based on such Poisson and binomial statistics. The limits in the tables are given for all confidence levels commonly used in astrophysics.
Oscillations in the NF-kB signalling pathway.

NF-κB oscillations were suggested by Hoffmann et al from electro-mobility shift assays (EMSA) in population studies of IκBα-/- embryonic fibroblasts and simulated in a computational model. NF-κB oscillations were also observed by Nelson et al at the single cell level. The Hoffmann model gave a fairly good pre- diction of Nelson et al oscillatory experimental data using fluorescent proteins. A common comment on the source of oscillations is the existence of negative feedback loops. Just from the point of mathematics, we can set up a simple system containing a negative feedback loop that possesses oscillating behaviour resembling the ones observed in the experiments like Fonslet et al did. However, different models with similar structures can have dramatically different dynam- ical behaviour. In order to understand biological mechanisms, it is necessary to work on those real models that are based on experimental data even though models may be very large. In this paper, we are able to analyze the dynamical properties of Hoffmann’s large computational model (containing 24 variables and 64 parameters) by using computational and analytical methods and give an explanation of the source of oscillations. We find that the computational model can be treated as a fast-slow system where the level of total IκB Kinase (IKK) is treated as a slow variable. If we consider the limit in which the level of total IKK does not change at all, then we can take the level of total IKK as a parameter. Since the total NF-κB is conserved in the model, we can also view the total NF-κB as a parameter. If the actual variation of IKK is sufficiently slow, then orbits in the true system trace attractors in the reduced model. We find that for some range of the level of NF-κB, the reduced system experiences Hopf bifurcation twice while varying the level of total IKK. The damped oscillations observed in the computational system come from the existence of stable limit cycles and stable spirals in the reduced system family.
Spatio-temporal motion-based foreground segmentation and shadow suppression

A relevant problem in computer vision is how to detect and track moving objects from video sequences efficiently. Some algorithms require manual calibration in terms of specification of parameters or some hypotheses. A novel method is developed to extract moving objects through multi-scale wavelet transform across background subtraction. The optimal selection of threshold is automatically determined which does not require any complex supervised training or manual calibration. The proposed approach is efficient in detecting moving objects with low contrast against the background and the detection is less affected by the presence of moving objects in the scene. The developed method combines region connectivity with chromatic consistency to overcome the aperture problem. Ghosts are removed by the proposed background update function, which efficiently prevents undesired corruption of background model and does not consider adaptation coefficient. The mentioned approach is scene-independent and the capacity to extract moving object and suppress cast shadow is high. The developed algorithm is flexible and computationally cost-effective. Experiments show that the proposed approach is robust and efficient in segmenting foreground and suppressing shadow by comparison.
BCJR trellis construction for binary linear block codes

A novel low-complexity trellis design technique for linear binary block codes is introduced. It is shown that, for some linear block codes, the problem of finding the permutation minimal trellis is very simple. For linear binary block codes, a heuristic algorithm for the reduction of trellis complexity is proposed. A reduction in trellis complexity is achieved by the implementation of a new permutation algorithm, which is based on column and row permutations in the minimal weight generator matrix of the code. The ‘permutation-oriented’ generator matrix for obtaining permutation minimal or near-minimal trellises is defined.
SINGULAR VALUE ROBUSTNESS TESTS FOR MISSILE AUTOPILOT UNCERTAINTIES

Singular value robustness tests that evaluate missile autopilot sensitivity to neglected/mismodeled dynamics and real parameter variations are presented. Robustness theorems by Doyle and Lehtomaki are used to evaluate autopilot sensitivity to neglected and mismodeled actuator dynamics and neglected bending dynamics. The structured singular value /t-test of Doyle is used to compute a multivariable stability margin and to evaluate autopilot sensitivity to uncertain aerodynamic stability derivatives, modeled as real parameter variations. The conservatism of these robustness tests is discussed.
Ozone loss in the 2002–2003 Arctic vortex deduced from the assimilation of Odin/SMR O3 and N2O measurements: N2O as a dynamical tracer

In this paper we investigate the evolution of the northern polar vortex during the winter 2002–2003 in the lower stratosphere by using assimilated fields of ozone (O3) and nitrous oxide (N2O). Both O3 and N2O used in this study are obtained from the Sub‐Millimetre Radiometer (SMR) aboard the Odin satellite and are assimilated into the global three‐dimensional chemistry transport model of Météo‐France, MOCAGE. O3 is assimilated into the ‘full’ model including both advection and chemistry whereas N2O is only assimilated with advection since it is characterized by good chemical stability in the lower stratosphere. We show the ability of the assimilated N2O field to localize the edge of the polar vortex. The results are compared to the use of the maximum gradient of modified potential vorticity as a vortex edge criterion. The O3 assimilated field serves to evaluate the ozone evolution and to deduce the ozone depletion inside the vortex. The chemical ozone loss is estimated using the vortex‐average technique. The N2O assimilated field is also used to substract out the effect of subsidence in order to extract the actual chemical ozone loss. Results show that the chemical ozone loss is 1.1 ± 0.3 ppmv on the 25 ppbv N2O level between mid‐November and mid‐January, and 0.9 ± 0.2 ppmv on the 50 ppbv N2O level between mid‐November and the end of January. A linear fit over the same periods gives a chemical ozone loss rate of ∼18 ppbv day−1 and ∼9.3 ppbv day−1 on the 25 ppbv and 50 ppbv N2O levels, respectively. The vortex‐averaged ozone loss profile from the O3 assimilated field shows a maximum of 0.98 ppmv at 475 K. Comparisons to other results reported by different authors using different techniques and different observations give satisfactory results. Copyright © 2008 Royal Meteorological Society
Toughness, minimum degree, and spanning cubic subgraphs

Degree conditions on the vertices of a t-tough graph G (1 t < 3) are presented which ensure the existence of a spanning cubic subgraph in G. These conditions are best possible to within a small additive constant for every fixed rational t2 [1,4=3) [ [2,8=3). 2003 Wiley Periodicals, Inc. J Graph Theory 45: 119–141, 2004
Characterization of a novel photon counting detector for clinical CT: count rate, energy resolution, and noise performance

We report on a characterization study of a multi-row direct-conversion x-ray detector used to generate the first photon counting clinical x-ray computed tomography (CT) patent images. In order to provide the photon counting detector with adequate performance for low-dose CT applications, we have designed and fabricated a fast application specific integrated circuit (ASIC) for data readout from the pixellated CdTe detectors that comprise the photon counting detector. The cadmium telluride (CdTe) detector has 512 pixels with a 1 mm pitch and is vertically integrated with the ASIC readout so it can be tiled in two dimensions similar to those that are tiled in an arc found in 32-row multi-slice CT systems. We have measured several important detector parameters including the maximum output count rate, energy resolution, and noise performance. Additionally the relationship between the output and input rate has been found to fit a non-paralyzable detector model with a dead time of 160 nsec. A maximum output rate of 6 × 106 counts per second per pixel has been obtained with a low output x-ray tube for CT operated between 0.01 mA and 6 mA at 140 keV and different source-to-detector distances. All detector noise counts are less that 20 keV which is sufficiently low for clinical CT. The energy resolution measured with the 60 keV photons from a 241Am source is ~12%. In conclusion, our results demonstrate the potential for the application of the CdTe based photon counting detector to clinical CT systems. Our future plans include further performance improvement by incorporating drift structures to each detector pixel.
Vibration control of Timoshenko beam traversed by moving vehicle using optimized tuned mass damper

The dynamic behavior of a combined bridge–vehicle system in which the bridge is modeled as a Timoshenko beam and the vehicle as a half-car planar model is investigated using the finite element method. The governing equations of motion of the Timoshenko beam with the attached tuned mass damper (TMD) traversed by a moving vehicle are obtained. Adesign optimization algorithm is developed in which the analysis module based on the derived finite element formulation has been combined with the optimization module using the sequential programming technique. The objective is to determine the optimum values of the parameters (frequency and damping ratios) of a TMD, in order to minimize the maximum frequency response of the beam midspan when traversed by a moving vehicle. Results obtained illustrate that by attaching an optimally TMD to the Timoshenko beam a significantly faster vibration control can be achieved.
Plasma convection in the magnetotail lobes: statistical results from Cluster EDI measurements

A major part of the plasma in the Earth's magnetotail is populated through transport of plasma from the solar wind via the magnetotail lobes. In this paper, we present a statistical study of plasma convection in the lobes for different directions of the interplanetary magnetic field and for different geomagnetic disturbance levels. The data set used in this study consists of roughly 340 000 one-minute vector measurements of the plasma convection from the Cluster Electron Drift Instrument (EDI) obtained during the period February 2001 to June 2007. The results show that both convection magnitude and direction are largely controlled by the interplanetary magnetic field (IMF). For a southward IMF, there is a strong convection towards the central plasma sheet with convection velocities around 10 km s −1 . During periods of northward IMF, the lobe convection is almost stagnant. A B y dominated IMF causes a rotation of the convection patterns in the tail with an oppositely directed dawn-dusk component of the convection for the northern and southern lobe. Our results also show that there is an overall persistent duskward component, which is most likely a result of conductivity gradients in the footpoints of the magnetic field lines in the ionosphere.