Miracle-dz/UniFAR-FTUs huggingface dataset:
Optical remote sensing of the thermosphere with HF pumped artificial airglow

Optical emissions excited by high-power radio waves in the ionosphere can be used to measure a wide variety of parameters in the thermosphere. Powerful high-frequency (HF) radio waves produce energetic electrons in the region where the waves reflect in the F region. These hot or suprathermal electrons collide with atomic oxygen atoms to produce localized regions of metastable O(1D) and O(1S) atoms. These metastables subsequently radiate 630.0 and 557.7 nm, respectively, to produce clouds of HF pumped artificial airglow (HPAA). The shapes of the HPAA clouds are determined by the structure of large-scale (≈10 km) plasma irregularities that occur naturally or that develop during ionospheric heating. When the HF wave is operated continuously, the motion of the airglow clouds follows the E × B drift of the plasma. When the HF wave is turned off, the airglow clouds decay by collisional quenching and radiation, expand by neutral diffusion, and drift in response to neutral winds. Images of HPAA clouds, obtained using both continuous and stepped radio wave transmissions, are processed to yield the electric fields, neutral wind vectors, and diffusion coefficients in the upper atmosphere. This technique is illustrated using data that were obtained in March 1993 and 1995 at the ionospheric modification facility near Nizhny Novgorod, Russia. Analysis of HPAA clouds yields zonal plasma drifts of 70 m s−1 eastward at night. On the basis of artificial airglow from energetic electrons generated at 260 km the zonal neutral wind speed was estimated to be 96 m s−1 and the O(1D) diffusion coefficient was determined to be between 0.8 and 1.4 × 1011 cm2 s−1. The quenched lifetime of the O(1D) was determined to be 29.4 s. The diffusion and quenching rates are directly related to the atomic and molecular concentrations in the thermosphere. Improvements in the remote-sensing technique may be obtained if the intensity of the artificial airglow emissions is increased. High-power radio transmissions employing pulse sequences and tuning near electron cyclotron harmonics were attempted to increase the optical emissions. Both of these, however, produced reduced intensity, and consequently, continuous transmission at frequencies away from electron gyro harmonics is the preferred heating regime.
Finding Reliable Shortest Paths in Dynamic Stochastic Networks

A reliable a priori shortest path (RASP) offers the least time budget and ensures that a traveler can arrive at the destination on time with the desired probability. A RASP is equivalent to enumerating all nondominated paths under the first-order stochastic dominance rule. Compared with the problem in static networks, the RASP problem becomes more complex in dynamic networks because it is more difficult to compute path travel time distributions. Two modules of process are the keys to solving the RASP problem. One module is the convolution scheme (how to compute a path travel time distribution from its member links' travel time distributions), and the other module is the stochastic dominance scheme (how to determine nondominated paths). This study aims to find an efficient solution algorithm for this problem. An alternative convolution method is developed on the basis of the adaptive discretization approach, which was originally proposed to solve the RASP problem in static networks. In contrast, the higher-order stochastic dominance rule can be shown to reduce the number of nondominated paths; this rule promises to improve computational efficiency. Numerical experiments show that the second-order stochastic dominance rule offers good approximations, and the central processing unit time is reduced by at least 50%.
High thermoelectric power factor in alloys based on CoSi

We have investigated the thermoelectric properties of alloys of composition CoSi1−xGex for 0≤x≤0.5. These alloys display Seebeck coefficient in the range of −80 to −100 μV K−1 at room temperature. Despite the rather high Seebeck coefficients, the electrical resistivity of these alloys is metallic in nature. Alloying on the Ge site strongly reduces the lattice thermal conductivity. The combination of high Seebeck coefficient and metallic resistivity leads to very high thermoelectric power factor in these alloys, with the best sample exhibiting a power factor higher than that of state of the art bismuth telluride-based thermoelectric alloys at room temperature.
All-fiber-optic temperature sensor based on reduced graphene oxide

We demonstrate a novel all-fiber-optic temperature sensor based on a reduced graphene oxide (rGO) film coated onto a side-polished fiber (SPF). Significantly enhanced interaction between the propagating light and the rGO film can be obtained via strong evanescent field of the SPF. The strong light–graphene interaction results in temperature sensing with a maximum optical power variation of 11.3 dB in the SPF experimentally. The novel temperature fiber sensor has a linear correlation coefficient of 99.4%, a sensitivity of 0.134 dB °C−1, a precision of better than 0.03 °C, and a response speed of better than 0.0228 °C s−1. Such an rGO-based all-fiber-optic temperature sensor is easy to fabricate, is compatible with fiber-optic systems, and possesses high potentiality in photonics applications such as all-fiber-optic temperature sensing networks.
Can we make sense out of the measurement process in relativistic quantum mechanics

We study the instantaneity of the state-reduction process in relativistic quantum mechanics. The conclusion of various authors that this instantaneity will restrict the set of relativistic observables to purely local ones (i.e., that the measurement of any nonlocal property of a system at a well-defined time would give rise to violations of relativistic causality) is found to be erroneous, and experiments (of a kind not encountered before in measurement theory) are described whereby certain nonlocal properties of some simple physical systems can be measured at a well-defined time without violating causality. The attempts of certain authors to reconcile the reduction process with the covariance of the relativistic quantum state are considered and found wanting, and it is argued that the covariance of relativistic quantum theories resides exclusively in the experimental probabilities, and not in the underlying quantum states. The problem of nonlocal measurement is considered in general: distinctions (which are not to be met with in the nonrelativistic case) arise in relativistic quantum mechanics between what can be measured for fermions and what can be measured for bosons, between what can be measured for individual systems and what can be measured for ensembles, and between what kinds of states canmore » be verified by measurement and what kinds of states can be prepared by measurement; and these pose difficult questions about the nature of measurement itself. « less
Hybrid estimation of cosmic microwave background polarization power spectra

This paper generalizes the hybrid power spectrum estimation method developed in a previous paper to the estimation of polarization power spectra of the cosmic microwave background radiation. The hybrid power spectrum estimator is unbiased and we show that it is close to optimal at all multipoles, provided the pixel noise satisfies certain constraints. Furthermore, the hybrid estimator is computationally fast and can easily be incorporated in a Monte Carlo chain for Planck-sized data sets, which may be essential to account for realistic noise covariance and systematic errors. Simple formulae are given for the covariance matrices, including uncorrelated inhomogeneous instrumental noise, and these are tested extensively against numerical simulations. We compare the behaviour of simple pseudo-C l (PCL) estimates with maximum-likelihood estimates at low multipoles. For realistic sky cuts, maximum-likelihood estimates reduce very significantly the mixing of E and B modes. To achieve limits on the scalar-tensor ratio of r << 0.1 from sky maps with realistic sky cuts, maximum-likelihood methods, or PCL estimators based on unambiguous E and B modes, will be essential.
Finite-time energy-to-peak filtering for Markov jump repeated scalar non-linear systems with packet dropouts

This study is concerned with the finite-time energy-to-peak filtering problem for Markov jump repeated scalar non-linear systems with packet dropouts. The packet dropout phenomenon occurs in a random way and is modelled by a stochastic variable satisfying the Bernoulli distribution. The purpose of the study is to design a filter such that the resulting filtering error system is stochastically finite-time bounded, and a prescribed energy-to-peak performance level is achieved over a finite time interval. By using the mode-dependent diagonally dominant Lyapunov function approach, some strict linear matrix inequality-based conditions are established for the existence of an admissible filter, and a corresponding explicit parameterisation of such a filter is obtained. Finally, a numerical example with simulation is presented to demonstrate the effectiveness of our proposed approach.
Plasma particle simulations of wake formation behind a spacecraft with thin wire booms

Double‐probe electric field sensors installed on scientific spacecraft are often deployed using wire booms with radii much less than typical Debye lengths of magnetospheric plasmas (millimeters compared to tens of meters). However, in tenuous and cold‐streaming plasmas seen in the polar cap and lobe regions, the wire booms, electrically grounded at the spacecraft, have a high positive potential due to photoelectron emission and can strongly scatter approaching ions. Consequently, an electrostatic wake formed behind the spacecraft is further enhanced by the presence of the wire booms. We reproduce this process for the case of the Cluster satellite by performing plasma particle‐in‐cell (PIC) simulations, which include the effects of both the spacecraft body and the wire booms in a simultaneous manner. The simulations reveal that the effective thickness of the booms for the Cluster Electric Field and Wave (EFW) instrument is magnified from its real diameter (2.2mm) to several meters, when the spacecraft potential is at tens of volts. Such booms enhance the wake electric field magnitude by a factor of 1.5–2 depending on the spacecraft potential and play a principal role in explaining the in situ Cluster EFW data showing sinusoidal spurious electric fields with about 10mV/m amplitude. The boom effects are quantified by comparing PIC simulations with and without wire booms and also by examining the wake formation for various spacecraft potentials.
A COMPARISON OF THE INTENSITIES AND ENERGIES OF GRADUAL SOLAR ENERGETIC PARTICLE EVENTS WITH THE DYNAMICAL PROPERTIES OF ASSOCIATED CORONAL MASS EJECTIONS

Gradual solar energetic particle (SEP) events observed at 1 AU are produced by shocks driven by coronal mass ejections (CMEs). Characterizations of the remotely imaged CMEs and of their associated SEP events observed in situ can be used to increase our ability to forecast SEP events and to understand better the physical connections between the two phenomena. We carry out a statistical comparison of the peak intensities Ip20, of 120 western-hemisphere 20 MeV SEP events with those of their associated CMEs observed by the Solar and Heliospheric Observatory/Large Angle and Spectrometric Coronagraph over the past solar cycle. For a subset of 96 events observed with the EPACT instrument on the Wind spacecraft we also compare the SEP 2 MeV peak intensities Ip2, power-law energy spectral exponents γ, total SEP energies Esep, and 2 MeV nuc−1 H/He ratios with CME properties. New analyses of white-light CME images enable us to improve calculations of the CME masses and potential energies and then to determine two values of their kinetic energies based on frontal V (fr) and center-of-mass V (cm) speeds. Despite considerable scatter in the SEP and CME data, the large dynamical ranges of both the SEP and CME parameters allow us to determine statistical trends in the comparisons of the logs of the parameters. Ip2, Ip20, and Esep are significantly correlated with CME kinetic energies, masses, and speeds, while γ trends lower (harder). Those correlations are higher with V (fr) than with V (cm) parameters, indicating a less significant role for the body of the CME than for the CME front in SEP production. The high ratios (⩾10%) of Esep to CME energies found by Mewaldt et al. are confirmed, and the fits are consistent with a linear relationship between the two energies. The 2 MeV nuc−1 H/He ratios decrease with increasing CME speeds, which may be an effect of shock geometry. We discuss several factors that limit the estimates of both the SEP and CME energies.
Emergent behaviors of a holonomic particle system on a sphere

We study sufficient conditions for the asymptotic emergence of synchronous behaviors in a holonomic particle system on a sphere, which was recently introduced by Lohe [“Non-Abelian Kuramoto model and synchronization,” J. Phys. A: Math. Theor. 42, 395101–395126 (2009)]. These conditions depend only on the coupling strength and initial position diameter. For identical particles, we show that the position diameter approaches zero asymptotically under these sufficient conditions, i.e., all particles approach to the same position. For non-identical particles, the particle positions do not shrink to one point, but can be squeezed into some small region whose diameter is inversely proportional to the coupling strength, when the coupling strength is large. We also provide several numerical results to confirm our analytical findings.
A lunar occultation and direct imaging survey of multiplicity in the Ophiuchus and Taurus star-forming regions

We present an IR lunar occultation and direct imaging search for companions in the Ophiuchus star-forming region and update a similar search of the Taurus region. The search is sensitive to companions in the angular separation range 0.005-10 sec. In Ophiuchus, we surveyed 35 young star targets; this sample contains at least 10 binaries, two triples, and one quadruple. Ten of the companion stars are newly discovered. In Taurus, the survey now includes 47 systems among which there are at least 22 binaries and four triples. Only two companion stars are newly identified because there is strong overlap with prior work. All the triples and quadruple are hierarchical. The observed binary frequency in Ophiuchus, in the 3-1400 AU range of separations, is at least 1.1 +/- 0.3 that of the nearby solar-like stars. This value is a lower bound because we make no corrections for incompleteness. In Taurus, in the same range of separations, the observed binary frequency is at least 1.6 +/- 0.3 that of the nearby solar-like stars. This value extends Ghez et al.'s (1993) and Leinert's et al.'s (1993) determination of an excess binary frequency to 3 AU separation. We used the weak-line T Tauri star/T Tauri star (WT/TT) type and the K-L color index to distinguish between systems with and without inner disks. We find no convincing difference in the binary frequency or distribution of separations of the systems with and without inner disks. The 1.3 mm continuum emission of the single systems exceeds that of the multiples suggesting that their extensive outer disks are more massive. The specific angular momenta of the binaries overlap those of molecular cloud cores measured by Goodman et al. (1993).
On Newtonian and non-Newtonian flow in complex geometries

A flow visualization technique by means of an expanded laser beam and trace amounts of particulate additives is used to study the behaviour of Newtonian and non-Newtonian elastic liquids in a number of complex geometries. Particular attention is paid to the effect of fluid elasticity on the flow characteristics. Attempts are made to simulate numerically the observed flows by using finite-difference techniques. The agreement between theory and experiment is very satisfactory.
Lipschitz stability in inverse parabolic problems by the Carleman estimate

We consider a system with a suitable boundary condition, where is a bounded domain, is a uniformly elliptic operator of the second order whose coefficients are suitably regular for , is fixed, and a function satisfies Our inverse problems are determinations of g using overdetermining data or , where and . Our main result is the Lipschitz stability in these inverse problems. We also consider the determination of , in the case of with given R satisfying on . Finally, we discuss an upper estimation of our overdetermining data by means of f.
Three-dimensional structures of MHD flow in a disk generator

Three-dimensional nonuniform plasmas and boundary layers have been studied numerically under an MHD interaction. The nonuniform plasma of "streamer" owing to weak ionization of seed material has a spiral structure in the r-/spl theta/ plane, and the plasma becomes almost uniform between the walls in the r-z plane. This structure is almost the same as that in our previous paper (1997), where the gas (heavy particle) properties are assumed to be invariant and steady. In addition to the streamer, the nonuniform plasma of "domain" owing to weak ionization of noble gas is revealed. The domain has the structure perpendicular to the streamer. In a strong MHD interaction case, the static pressure considerably increases in the upstream region of a generation channel, and the pseudo-shock waves appear in the generator, but the plasma is almost uniform along the /spl theta/ direction. The boundary layer in the strong MHD interaction is considerably thick, and in the broad region near the wall the Hall current flows reversely. In the weak MHD interaction case, the plasma forms a nonuniform structure along the /spl theta/ direction, and the Hall current does not always flow in the opposite direction even on the insulator wall since the azimuthal electric field is not zero.
Adaptive estimation of time delays in sampled data systems

An adaptive technique is developed which iteratively determines the time delay between two sampled signals that are highly correlated. Although the procedure does not require a priori information on the input signals, it does require that the signals have a unimodal or periodically unimodal cross-correlation function. The adaptive delay algorithm uses a gradient technique to find the value of the adaptive delay that minimizes the mean-squared (MS) error function. This iterative algorithm is similar to the adaptive filter coefficient algorithm developed by Widrow. However, the MS error function for the adaptive delay is not quadratic, as it is in the adaptive filter. A statistical analysis determines the value of the convergence parameter which effects rapid convergence of the adaptive delay. This convergence parameter is a function of the power of the input signal. Computer simulations are presented which verify that the adaptive delay correctly estimates the time delay difference between two sinusoids, including those in noisy environments. The adaptive delay is also shown to perform correctly in a time delay tracking application.
Arecibo emission-absorption observations of Galactic OH

Observations of OH emission/absorption toward 19 low-Galactic-latitude background-continuum sources are reported. Data obtained at 1.665 and 1.667 GHz using the 12-m radio telescope at Arecibo Observatory during February-March 1984, are presented in extensive tables and graphs and characterized in detail, with reference to theoretical models. A total of 11 OH absorption features were detected toward nine of the sources, with an average of one feature of optical depth 0.02 or greater per 5 kpc of path length and an average column density of 1.6 x 10 to the 12th/sq cm (corrected to b = 90 deg). 35 references.
Data transmission with mean-square partial response

The authors investigate the use of mean-square-partial response (MSPR) channel signaling for symbol-by-symbol detection of a channel with controlled intersymbol interference. They show that, by filtering the received channel output with what they call a mean-square whitened matched filter, the overall detection SNR (signal-to-noise ratio) for symbol-by-symbol detection is as high as possible. In some cases, an uncoded improvement of 0.5-4.0 dB is possible with respect to existing partial response methods, referred to as zero-forcing partial response. A Tomlinson predecoder in concatenation with good trellis codes is used to combine the gain of the MSPR and trellis coding. It is shown that, with the MSPR system, optimization of the transmit filter leads to a system that is as close to its capacity as transmission on the flat AWGN (additive white Gaussian noise) channel is to its capacity. The authors also show that, when such a coded system has optimized transmit bandwidth, the cutoff rate is achievable with existing (most powerful) codes at an error rate 10/sup -6/. A modified duobinary channel is used to illustrate the potential gains. <<ETX>>
Numerical and experimental analysis of laminar flow through square-edged orifice with variable thickness

In this work, axisymmetric, viscous, steady, incompressible and laminar flow through square-edged orifices has been studied. A numerical solution of the steady-state vorticity transport equation has been obtained from the two-dimensional Navier-Stokes equations. Finally, streamline patterns, vortex formations and separated flow regions have been predicted. The effects of orifice plate thickness and Reynolds number on the flow characteristics have been investigated numerically and experimentally. The Navier-Stokes equations have also been integrated in order to compute the pressure distributions through the orifice. From these results, the orifice discharge coefficient has been computed and examined as the Reynolds number and the orifice plate thickness were varied. A comparison has been made between the experimental results, the numerical predictions and available experimental results. The predicted flow discharge coefficient values agreed closely with the experimental results.
NMR study of the 3 d ferromagnetic metals: Critical region and paramagnetic phase

The ferromagnetic transition metals iron, nickel, and cobalt have been investigated by nuclear magnetic resonance up to the critical region and, in the case of nickel and cobalt, in the paramagnetic phase. The measurements include the zero-field resonant frequency, spin-spin relaxation rate, and spin-lattice relaxation rate in the ferromagnetic phase, and the Knight shift and spin-lattice relaxation rate in the paramagnetic phase. The data yield values of the static critical exponent ($\ensuremath{\beta}$) for the spontaneous magnetization and the dynamic exponent ($z$) for spin fluctuations near the critical points of all three ferromagnetic metals. Paramagnetic-phase data for nickel and cobalt yield the $d$-spin hyperfine coupling and the orbital Knight shift and susceptibility contributions. Magnetic equation-of-state parameters are derived for nickel and cobalt. Noncritical spin-spin relaxation rates in the ferromagnetic phase are attributed mainly to Suhl-Nakamura interactions, but in bulk metal samples the rates exhibit a striking and unexplained maximum between room temperature and the critical point.
[IEEE 2009 IEEE/PES Power Systems Conference and Exposition (PSCE) - Seattle, WA, USA (2009.03.15-2009.03.18)] 2009 IEEE/PES Power Systems Conference and Exposition - A Heuristic Constructive Algorithm for capacitor placement on distribution systems

This paper presents a heuristic constructive algorithm (HCA) for optimal capacitor placement on distribution systems. This is a nonlinear mixed integer optimization problem. In the proposed approach, the integer variables are represented using sigmoid function, thus interior point optimal power flow formulation can be applied to obtain sensitivity indexes based on Lagrange multipliers, reactive power, and bus voltage. The methodology is applied to two power distribution systems, and the results are compared with those obtained using a genetic algorithm approach.