Miracle-dz/UniFAR-FTUs huggingface dataset:
Key Exchange Protocol in Elliptic Curve Cryptography with No Public Point

In recent years some cryptographic algorithms have gained popularity due to properties that make them suitable for use in constrained environment like mobile information appliances, where computing resources and power availability are limited. One of these cryptosystems is Elliptic curve which requires less computational power, memory and communication bandwidth compared to other cryptosystem. This makes the elliptic curve cryptography to gain wide acceptance as an alternative to conventional cryptosystems (DSA, RSA, AES, etc.). All existing protocols for elliptic curve cryptosystems that are used for either key exchange or for ciphering, assume that the curve E, the field Fq and a point P on the curve are all public. In this research we propose a modified protocol for elliptic curve key exchange based on elliptic curve over rings, assuming that only the curve E and Fq are public, keeping the base point P secret, which make attacking the cryptosystem harder by the eavesdropper. Also we provide imbedded authentication, so our protocol does not suffer from the man in the middle attack.
Minimum principle for partially observable nonlinear risk-sensitive control problems using measure-valued decompositions

This paper is concerned with the derivation of a minimum principle for partially observed controlled diffusions with correlation between signals and observation noises, when the sample cost criterion is an exponential of integral. Instead of considering the information state which satisfies a version of Zakai's equation, measure-valued decompositions are employed to convert this equation into a P-a.s. deterministic equation, thus avoiding the basic finite dimensional approximation approach. Using weak control variations the minimum principle is derived. It consists of a modified version of Zakai's equation, an adjoint process satisfying a stochastic partial differential equation with terminal condition, and a Hamiltonian functional. This minimum principle is then applied to solve the linear-exponential-quadratic-Gaussian trackmgjproblem. The results of this paper are important in relating H ∞ or robust control problems and risk-sensitive control problems
Non-Wiener solutions of the adaptive noise canceller with a noisy reference

The performance of the adaptive noise canceller is typically analyzed in terms of Wiener filter theory. However, it has recently been shown by Glover that a narrow-band signal in the reference at a frequency for which there is no correlated signal in the primary gives rise to a notch in the output spectrum, a solution which lies outside the scope of the classical theory. In this paper an analytic expression for the output spectrum is derived for the more general case of a reference signal containing a sinusoid in white noise. It is found that although the notch depth is a decreasing function of the reference signal-to-noise ratio, the exact relationship also depends on the primary input; thus, with noise present, there is no longer a time-invariant relationship between the output and primary spectra. These results are shown to reduce to those of Glover and the classical Wiener filter in the appropriate contexts.
Hemodynamic measurements in deep brain tissues of humans by near-infrared time-resolved spectroscopy

Using near-infrared time-resolved spectroscopy (TRS), we measured the human head in transmittance mode to obtain the optical properties, tissue oxygenation, and hemodynamics of deep brain tissues in 50 healthy adult volunteers. The right ear canal was irradiated with 3-wavelengths of pulsed light (760, 795, and 835nm), and the photons passing through the human head were collected at the left ear canal. Optical signals with sufficient intensity could be obtained from 46 of the 50 volunteers. By analyzing the temporal profiles based on the photon diffusion theory, we successfully obtained absorption coefficients for each wavelength. The levels of oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), total hemoglobin (tHb), and tissue oxygen saturation (SO2) were then determined by referring to the hemoglobin spectroscopic data. Compared with the SO2 values for the forehead measurements in reflectance mode, the SO2 values of the transmittance measurements of the human head were approximately 10% lower, and tHb values of the transmittance measurements were always lower than those of the forehead reflectance measurements. Moreover, the level of hemoglobin and the SO2 were strongly correlated between the human head measurements in transmittance mode and the forehead measurements in the reflectance mode, respectively. These results demonstrated a potential application of this TRS system in examining deep brain tissues of humans.
The synchro-Compton limit of the brightness temperature of nonstationary radio sources

The brightness temperature of synchrotron emission from nonstationary radio sources during the cooling down by the inverse Compton effect is calculated. It is shown that brightness temperatures as high as 5 x 10 15 K at 1 GHz are allowed during the first day after injection of relativistic electrons of sufficiently high energy. This is about four orders of magnitude higher than the canonical synchro-Compton limit introduced by Kellermann & Pauliny-Toth (1969, ApJ, 155) for stationary radio sources
Precursors and Broadband Beer's Law: A Discussion on Sub-exponential Decay of Ultrafast Pulses in Water

We present a qualitative description of the precursor phenomena to place their ex- istence in the context of a practical application. We assert that precursors are nothing more than the time-domain representation of a linear broadband Beer's law. We support this description with absorption measurements of femtosecond pulses through 7 meters of water, and suggest that further deviations from Beer's law in water may be observed due to saturation efiects.
Constrained switching stabilization of linear uncertain switched systems using piecewise linear Lyapunov functions

The problem of switching stabilizability of linear uncertain switched systems with unstable modes has recently attracted increased interest. For a given collection of unstable linear uncertain subsystems, the problem is to determine asymptotically stabilizing switching signals or to ascertain the absence of such laws. In this paper, we deal with the switching stabilizability problem for a class of autonomous continuous-time switched linear systems with time-varying parametric uncertainties in the presence of additional state constraints. With a special emphasis on two-dimensional systems we extend previous relevant results in the literature, and we propose a computational technique that generates piecewise linear Lyapunov functions of a convex or non-convex nature. The algorithm is graph-based and consists of determining controlled invariant polytopes induced by systematic conic decompositions of the state-space and corresponding state-dependent switching control actions. Further extension of this computational tool to higher dimensional systems is also discussed.
Least-squares based inverse reconstruction of in-line digital holograms

We present a least-squares solution for the inverse problem in in-line digital holography which is based on a point source model. We demonstrate that by reformulating the reconstruction problem as an inverse problem and by integrating a contour gradient based auto-focus search algorithm into the reconstruction routine, a more fundamental solution for the inversion of a hologram can be attained. With this approach the inversion can be calculated without any prior knowledge of the object’s shape/size and without imposing any constraints on the imaging system. In a proof-of-concept study we show that our method facilitates a more accurate reconstruction, as compared to conventional methods, and that it facilitates object localization with an accuracy on the order of the optical wavelength.
Post-Modeling Histogram Matching of Maps Produced Using Regression Trees

Spatial predictive models often use statistical techniques that in some way rely on averaging of values. Estimates from linear modeling are known to be suscep- tible to truncation of variance when the independent (predictor) variables are measured with error. A straightforward post-processing technique (histogram matching) for attempting to mitigate this effect is pre- sented, and a comparison with untransformed model estimates is made. Histogram matching enhanced the contrast visible in the final map and produced estimates that mimicked the range of estimates in the original data set but performed worse overall with respect to absolute error of prediction. Examples of cases where histogram matching might be an effective post-pro- cessing method are given.
Analysis of micro fracture in human Haversian cortical bone under transverse tension using extended physical imaging

We propose a procedure to investigate local stress intensity factors at the scale of the osteons in human Haversian cortical bone. The method combines a specific experimental setting for a three‐point bending millimetric specimen and a numerical method using the eXtended Finite Element Method (X‐FEM). The interface between the experimental setting and the numerical method is ensured through an imaging technique that analyses the light microscopy observations to import the geometrical heterogeneity of the Haversian microstructures, the boundary conditions and appearing crack discontinuities into the numerical model. The local mechanical elastic Young's moduli are measured by nano‐indentation, and the Poisson ratios are determined by an imaging technique of the stress–strain fields. The model is able to access three scales of measurement: the macro scale of the material level (mm), the micro scale inside the Haversian material for stress–strain fields (10–100µm), and the sub‐micro scale for the crack opening profiles (1–10µm ) and fracture parameters (stress intensity factors). The model is applied to several patients at different aging stages. Copyright © 2009 John Wiley & Sons, Ltd.
Prony’s method for exponential lifetime estimations in fluorescence‐based thermometers

Noniterative algorithms using Prony’s method are proposed for the estimation of the exponential lifetime in fluorescence‐based fiber‐optic sensor systems. The uses of a variety of Prony’s algorithms are evaluated using Monte Carlo simulations. It is shown that the performance of Prony’s algorithms is quite close to that of Marquardt algorithms and they are the better alternatives to their Marquardt counterparts, when illustrated for real‐time applications in temperature sensors with a 98% decrease in running time.
Propagation of Sound Waves in Partially Saturated Soils

We investigate the propagation of sound waves by means of a newly constructed model in a sandstone filled with two immiscible fluids. The speeds and attenuations of the four emerging waves (one transversal, three longitudinal) are illustrated in dependence on frequency and initial saturation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On 2MASS Identifications for OH/IR Stars

Most OH/IR stars discovered by color selection from the IRAS Point Source Catalog have 5″–15″ quality positions, whereas the density of 2MASS sources around them is typically ∼0.005 arcsec-2. About 40% of positional associations within 5″ are thus false. This confusion can be reduced by a factor of 8 by discarding potential associations with inappropriate J-Ks colors. It is further reduced for OH/IR stars within 4. °5 of the Galactic plane by the availability of ∼ 2″ quality positions from the Midcourse Space Experiment. We use a sample of IRAS-derived OH/IR stars with radio positions from the VLA and extant 2MASS data to assess the likelihood of finding valid near-IR identifications for stars with thick circumstellar shells, and the residual probability of making a false 2MASS identification. Two noteworthy results are that (1) 19440+2251 cannot be associated with a 2MASS source satisfying J-Ks> 2; and (2) the candidate hypergiant star 19566+3423, alias MSX5C G070.7763+02.6837, which has an LRS 36 type, has a positional association with 2MASSI 1958322+343133 and a Ks = 14.2 ± 0.1.
Magnetic stabilization of the buoyant convection between infinite horizontal walls with a horizontal temperature gradient

Buoyant convection induced between infinite horizontal walls by a horizontal temperature gradient is characterized by simple monodimensional parallel flows. In a layer of low-Prandtl-number fluid, these flows can involve two types of instabilities: two-dimensional stationary transverse instabilities and three-dimensional oscillatory longitudinal instabilities. The stabilization of such flows by a constant magnetic field (vertical, or horizontal with a direction transverse or longitudinal to the flow) is investigated in this paper through a linear stability analysis and energy considerations. The vertical magnetic field stabilizes the instabilities more quickly than the horizontal fields, but the stabilization is only obtained up to moderate values of Hartmann number $Ha$ (before disappearance of the instabilities). Characteristic laws, given by the critical Grashof number $\Gr_c$ as a function of $Ha$ (proportional to the intensity of the magnetic field), have been found for the initial stabilization at small $Ha$. They are $\Gr_c \sim \Gr_{c_0} \exp(Ha^2)$ for the two-dimensional instabilities and $\Gr_c - \Gr_{c_0} \sim Ha^2$ for the three-dimensional instabilities (where $\Gr_{c_0}$ is the critical Grashof number at $Ha=0$), indicating that the three-dimensional instabilities, less stabilized, will prevail in a vertical magnetic field. It has been shown by an energy analysis that the strong stabilization of the two-dimensional instabilities is connected to the strong diminution of the destabilizing shear energy term when the velocity profiles are modified by the vertical magnetic field, and affected little by the Lorentz energy term. For the horizontal magnetic fields, the stabilization is very weak at small $Ha$, but then reaches an asymptotic behaviour corresponding to $\Gr_c \sim Ha$. This asymptotic stabilization is connected to the decrease of the destabilizing shear energy term due to the increase of the marginal cell length in the horizontal magnetic field. In fact, this stabilization only concerns the two-dimensional modes in the longitudinal field and the three-dimensional modes in the transverse field.
Single-pulse arc production of carbon nanotubes in ambient air

Multi-wall nanotubes (MWNTs) of carbon were produced by pulsed arc discharges between a room temperature sample and a counter-electrode, with peak currents of 7–100 A, and pulse lengths of 0.2–26 µs, in open air at selected locations on the sample. The samples were 10 × 10 mm2 graphite plates, carbon-coated 200 mesh copper grids, and Ni-coated glass slides. The counter-electrodes were graphite in the form of 1 × 4 mm2 bars or 4 mm diameter rods with a cone tip of 28°, or 0.1 mm diameter steel rods. Randomly oriented MWNTs (typically 5–15 walls) with a diameter of ~ 10 nm and lengths of up to 3 µm were produced on the samples with a single 0.2 µs pulse, implying linear growth rates of up to 15 m s−1. MWNTs were produced with both polarities and with all types of counter-electrodes used when the substrate contained carbon. Near vertically oriented MWNTs were deposited on the Ni/glass samples using a graphite counter-electrode. The simplicity, rapidity and selectivity of the process may facilitate wider study and practical application.
Bootstrapped Confidence Intervals as an Approach to Statistical Inference

Confidence intervals are in many ways a more satisfactory basis for statistical inference than hypothesis tests. This article explains a simple method for using bootstrap resampling to derive confidence intervals. This method can be used for a wide variety of statistics—including the mean and median, the difference of two means or proportions, and correlation and regression coefficients. It can be implemented by an Excel spreadsheet, which is available to readers on the Web. The rationale behind the method is transparent, and it relies on almost no sophisticated statistical concepts.
Organic photovoltaic power conversion efficiency improved by AC electric field alignment during fabrication

Ultra-low frequency AC field was employed to align p/n polymers during organic photovoltaic device fabrication. The resulting devices show 15% increase in power conversion efficiency and four-fold increase in parallel resistance. Supported by the transmission electron microscopy and atomic force microscopy images, the performance enhancement is attributed to the optimized morphology and enlarged p/n interface by AC field, which is more effective than DC, possibly explained by the argument of better mixing via back-and-forth shaking than a single swing.
Growth of highly strain-relaxed Ge1−xSnx/virtual Ge by a Sn precipitation controlled compositionally step-graded method

We have investigated Sn precipitation and strain relaxation behaviors in the growth of Ge1−xSnx layers on virtual Ge substrates (v-Ge) for strain engineering of Ge. By varying misfit strain at Ge1−xSnx∕v-Ge and Ge1−ySny∕Ge1−xSnx interfaces, we found that a critical misfit strain controls the onset of Sn precipitation at a given thickness of the Ge1−xSnx layer. A compositionally step-graded method, in which the critical misfit strain is taken into account, was applied to the growth of strain-relaxed Ge1−xSnx layers on v-Ge. Postdeposition annealing at each growth step led to lateral propagation of threading dislocations preexisting in the layer and originating from v-Ge, which resulted in high degree of strain relaxation. An epitaxial Ge layer was grown on the strain-relaxed Ge1−xSnx layer and an in-plane tensile strain of 0.68% was achieved.
Ultrafast dynamics in asymmetrical multiple quantum well SOAs

A numerical model for the investigation of the ultrafast gain properties in asymmetrical multiple quantum-well semi-conductor optical amplifiers (AMQW SOAs) has been developed considering propagation of ultrashort optical pulses with different wavelengths. The dynamics of the number of carriers and carrier temperature are investigated for each quantum well. The results agree with the experimental results of pump probe measurements with different wavelengths. It is shown that gain recovery is slower for higher energy wells for pump signals of all wavelengths.
Wavelet transforms for infrared applications

The wavelet transform has gained much in popularity recently. Although the concepts underlying the wavelet transform have been used for some time, it is only in the last seven years that it began to have an impact, especially on signal and image processing. Wavelets have applications in differential equations, signal processing, image and video compression, and many other domains. We provide a brief introduction to wavelets and wavelet analysis, and compare the wavelet and Fourier transforms. The wavelet transform allows us to analyze nonstationary signals, which the Fourier transform cannot. This is a very important property of wavelets. A wavelet decomposition makes it possible to analyze a signal both in time (or space) and frequency domains and is appropriate for multiresolution analysis. One interesting application of wavelets is image fusion. For this application we take the wavelet transform of images coming from different sensors (e.g., visible and infrared). This provides us with a multiresolution description of visible and infrared images. The two images are then merged at each level of resolution. Applying the inverse wavelet transform on the resulting image generates a new image which is a composite of the two original ones. This concept can be applied to more than two images whether they are in the same spectral band or not. Some results are presented and compared with the classical pyramidal algorithms of Burt and Toet.
Method for fuzzy rules extraction from numerical data

A method for extraction of fuzzy rules from numerical input-output data is proposed. The main idea consists in separation of the input space into activation rectangles, corresponding to different output intervals. The generation of fuzzy rules and membership functions is based on these activation rectangles, whereas an appropriate fuzzy rules inference mechanism is proposed. The method formalises the synthesis of the fuzzy system and could be used for function approximation, classification and control purposes. An illustrative example for implementation of the method for synthesis of traffic fuzzy control is given.
The quantization error of self-similar distributions

We prove results on the asymptotic behavior of the quantization error for self-similar distributions $P$ when $n$, the number of prototypes, goes to infinity. In particular, we show that the suitably scaled quantization error converges, if $P$ is nonarithmetic and that it is asymptotically periodic in the arithmetic case. The results hold also for distributions that are absolutely continuous with respect to a self-similar distribution.
Orthogonal projections based algorithm for array signal subspace estimation

Subspace-based methods rely on eigenvalue decomposition (EVD) or singular value decomposition (SVD) of a data matrix to compute the array signal or noise subspace, and thus inevitably lead to intensive computational complexity besides a large algorithmic delay. In this paper, an orthogonal projections based algorithm for array signal subspace estimation (OP) is proposed, where by exploiting a reference signal with known waveform the orthogonal projections of array data are calculated step by step to form a set of basis vectors for the signal and/or noise subspace without eigendecomposition. The subspace formed by the OP algorithm is proved mathematically to be equivalent to the real signal subspace. Signal subspace estimation error function and noise subspace estimation error function are defined to evaluate subspace estimation precision. Statistical analysis and simulation results show that the OP algorithm is computationally simple and the subspace estimation precision is roughly equivalent to that of EVD. At the end of the paper, an application to direction-of-arrival (DOA) estimation verifies the good performance of the OP algorithm.
Coherent charge oscillations in tunnel junctions

Small-capacitance junctions driven by a weak external current Ix may exhibit oscillations of the voltage with fundamental frequencies f2 = Ix/2e or f1 = Ix/e, thus reversing the role of current and voltage in comparison to the usual a.c. Josephson effect. These Bloch oscillations reflect the properties of the energy bands En(Qx), where Qx is an external charge, and thus demonstrate the macroscopic quantum-mechanical nature of the system. Cooper pair tunnelling by itself would lead to 2e-periodic energy bands and band gaps. Quasi-particle tunnelling makes the bands e-periodic, but opens no further gaps. Depending on the strength of this process, the bands are qualitatively modified, with a phase transition occurring at a critical strength. The spectrum of the voltage oscillations reflects these modifications and the phase transition.
Foundations of higher-order variational theory on Grassmann fibrations

A setting for higher-order global variational analysis on Grassmann fibrations is presented. The integral variational principles for one-dimensional immersed submanifolds are introduced by means of differential 1-forms with specific properties, similar to the Lepage forms from the variational calculus on fibred manifolds. Prolongations of immersions and vector fields to the Grassmann fibrations are defined as a geometric tool for the variations of immersions, and the first variation formula in the infinitesimal form is derived. Its consequences, the Euler–Lagrange equations for submanifolds and the Noether theorem on invariant variational functionals are proved. Examples clarifying the meaning of the Noether theorem in the context of variational principles for submanifolds are given.