Miracle-dz/UniFAR-FTUs huggingface dataset:
O interstitial generation and diffusion in high temperature annealed Si/SiO2/Si structures

The profile of oxygen atoms diffused from SiO2 films into Si substrates as interstitials during high temperature annealing has been studied by infrared absorption spectroscopy using 18O as a tracer. The measured absorbance profile in the substrates can be explained in terms of a simple diffusion model in which the SiO2 layer acts as a reservoir of O and there is no energy barrier to diffusion across the Si/SiO2 interface. The driving force for diffusion is the temperature‐dependent solubility of oxygen interstitials in the Si. We find evidence both for the outdiffusion of oxygen from the SiO2 layer into the Si during extended annealing and retrodiffusion back into the SiO2 layer during temperature ramp down. From etchback profiling data on O interstitials we are able to revise the Arrhenius law for O diffusion in Si and obtain an activation energy of 2.57 eV and a preexponential factor of 0.22 cm2 s−1. It is further suggested that there is evidence for enhancement of the O diffusion coefficient in Si at l.
Exosat observations of broad iron K line emission from Scorpius X-1

Using the Exosat Gas Scintillation Proportional Counter a broad iron K emission line is found to be present in the X-ray spectrum of Sco X-1. The line full width half-maximum (FWHM) is 0.7 keV, independent of the source intensity state. During flaring intervals the line intensity remains constant such that the equivalent width, decreases from 50 eV to 25 eV across a flare. During quiescent intervals lasting several hours or more the line flux can decrease by up to a factor of 2. The line centroid is centered on 6.75 keV. The observed line width suggests Compton broadening by a hot scattering cloud with an optical depth of a few. The invariance of the line FWHM during flares rules out the previously suggested self-Comptonized thermal bremsstrahlung model. The line more likely originates in an optically thick accretion disk corona that lies at 100 to 1000 neutron star radii. The 2-25 keV continuum can be modeled as a blackbody plus unsaturated Comptonized spectrum. The flaring is caused by increases in the luminosity of the blackbody component from 10 percent to 40 percent of the total. The two-component continuum model is interpreted in terms of disk accretion onto a neutron star withmore » a weak magnetic field and the inner accretion disk terminated at the neutron star surface by a boundary layer. 45 references. « less
Three-dimensional blade–vortex interaction in the strong vortex regime

A study of three-dimensional interaction between a blade and an initially columnar vortex was performed using flow visualization experiments and computer simulations for problems where the blade is translated normal to and impacts upon the vortex core. The reported research focuses on cases where the vortex is sufficiently strong that the blade boundary layer separates before the blade penetrates into the vortex core. The study examines the topology and evolution of the separated secondary vorticity from the blade and its interaction with the primary vortex. In particular, it is observed that the separated vorticity from the blade has the form of a series of vortex loops that wrap around the outer surface of the primary vortex core and spread both upstream and downstream along the vortex axis. Both the initial formation of these vortex loops and their eventual interaction with the primary vortex are investigated. Computations based on a series of idealized models of the secondary vorticity are performed i.
The abundance of N-14 at the cosmic-ray source - A study using new fragmentation cross sections

The abundance of N-14 at the Galactic cosmic ray source was examined using new fragmentation cross sections measured by the University of New Hampshire group for 12 different source nuclei (ranging from C-12 to Ni-58) which cover about 70 percent of all cosmic-ray nuclei arriving at earth. A new cross-section program was used to estimate unmeasured cross sections. These cross sections were then incorporated into a Galactic propagation program to calculate the interstellar production of B and N. Results indicate that atomic selection effects alone cannot explain adequately the observed depletion of N-14 relative to O-16 in the cosmic-ray source with respect to the solar corona, indicating that some part of this depletion must have a nuclear/nucleosynthetic origin. 57 refs.
The singing wineglass: an exercise in mathematical modelling

Lecturers in mathematical modelling courses are always on the lookout for new examples to illustrate the modelling process. A physical phenomenon, documented as early as the nineteenth century, was recalled: when a wineglass ‘sings’, waves are visible on the surface of the wine. These surface waves are used as an exercise in mathematical modelling. Based on assumptions about the wine in the glass and observations illustrated with photographs, a mathematical problem is set up. This problem includes a non-homogeneous Neumann boundary condition on the lateral side of the glass. The solution to the mathematical problem is animated using Mathematica™. The predictions of the model are tested by comparing them with the known facts. The predictions of the model agree with the actual observations.
On the Transformation of a Tropical Easterly Wave into a Tropical Depression: A Simple Numerical Study

Abstract Through the time integration of a simple numerical model, the transfomation of a tropical easterly wave into a tropical depression was investigated. The initial condition selected for the model is a slowly decaying adiabatic linear normal mode resembling an easterly wave. It was found that the addition of a CISK (conditional instability of the second kind) type heating effect to the model results in the growth of the wave. Addition of the nonlinearity effect alone, which includes the nonlinear zonal advection and vertical stretching of relative vorticity, has little impact on the wave evolution. However, if the above nonlinearity effect is combined with the heating effect, it can cause the contraction of the disturbance and enhance the development The initial free wave undergoes significant structural changes during its transformation into a developing system. Experiments were also performed for three different waves under various basic flow conditions. The obtained results agree with a conclusio.
Some path properties of weighted-fractional Brownian motion

In this paper we consider the weighted-fractional Brownian motion with indexes a, b () and narrow the focus to obtain some properties of sample paths. Motivated by the asymptotic propertyfor all s>0, we consider the -strong variation of the principal value type defined by the limitwith for all t>0, where the limits are uniform in probability on each compact interval. We show that is strongly locally -non-deterministic with , and by applying this property we study Chung's law of the iterated logarithm for and intersection local time on .
Effects of diffusion on solar models and their oscillation frequencies

Settling and diffusion of helium have significant effects on the structure of solar models and their oscillation frequencies. We examine these effects in considerably more detail than has been done before, and we compare the computed frequencies with an extensive set of observed frequencies. We find that inclusion of diffusion results in a significant improvement in the agreement between theory and observations
A k‐Factor GARMA Long‐memory Model

Long‐memory models have been used by several authors to model data with persistent autocorrelations. The fractional and fractional autoregressive moving‐average (FARMA) models describe long‐memory behavior associated with an infinite peak in the spectrum at f = 0. The Gegenbauer and Gegenbauer ARMA (GARMA) processes of Gray, Zhang and Woodward (On generalized fractional processes. J. Time Ser. Anal. 10 (1989), 233–57) can model long‐term periodic behavior for any frequency 0 ≤f≤ 0.5. In this paper we introduce a k‐factor extension of the Gegenbauer and GARMA models that allows for long‐memory behavior to be associated with each of k frequencies in [0, 0.5]. We prove stationarity conditions for the k‐factor model and discuss issues such as parameter estimation, model iden‐ tification, realization generation and forecasting. A two‐factor GARMA model is then applied to the Mauna Loa atmospheric CO2 data. It is shown that this model provides a reasonable fit to the CO2 data and produces excellent forecasts.
Low‐temperature dielectric properties of candidate substrates for high‐temperature superconductors: LaAlO3 and ZrO2 : 9.5 mol % Y2O3

The effects of temperature (4–400 K), hydrostatic pressure and frequency on the dielectric constant, e’, and dielectric loss of single crystals of LaAlO3 and cubic yttria(9.5 mol %)‐stabilized zirconia (ZrO2) were investigated. Both crystals are relatively low‐loss, low‐dispersion dielectrics in the temperature range (T<150 K) of most interest for high‐temperature superconductors. The pressure results make it possible to evaluate the various contributions to the temperature dependence of e’. It is found that this dependence is dominated by the change of polarizability with volume. The dielectric properties of the two crystals are compared with those of other candidate substrate materials.
Coupled Line-Profile and Continuum Variations in EZ Canis Majoris: Implications for the Driving Mechanism of Global Wind Structures in Wolf-Rayet Winds

EZ CMa is an apparently unusual Wolf-Rayet star of the nitrogen sequence that exhibits strong variations on a period of 3.77 days with coherency lasting typically about 10 cycles. We have used an extensive set of optical spectroscopic observations to investigate a possible link between its line-profile and photometric continuum variability. Despite the strong epoch dependency of the variations, a persistent correlation is found between changes in the wind line profiles (N V λλ4604, 4620 in particular) and in continuum flux emanating near the stellar core. We suggest that these observations give further support to the idea that the physical conditions prevailing in the vicinity of the star's photosphere have a significant impact on the wind structure and that a spatial dependence of these conditions at the base of the outflow induces the formation of azimuthal wind structures in EZ CMa. The epoch-dependent nature of the variability could be related to long-term behavior of corotating magnetic structures, although pulsational instabilities constitute a viable alternative.
Elastomeric transparent capacitive sensors based on an interpenetrating composite of silver nanowires and polyurethane

Highly flexible transparent capacitive sensors have been demonstrated for the detection of deformation and pressure. The elastomeric sensors employ a pair of compliant electrodes comprising silver nanowire networks embedded in the surface layer of polyurethane matrix, and a highly compliant dielectric spacer sandwiched between the electrodes. The capacitance of the sensor sheets increases linearly with strains up to 60% during uniaxial stretching, and linearly with externally applied transverse pressure from 1 MPa down to 1 kPa. Stretchable sensor arrays consisting of 10 × 10 pixels have also been fabricated by patterning the composite electrodes into X-Y addressable passive matrix.
Anode material based on Zr-doped ZnO thin films for organic light-emitting diodes

Zr-doped ZnO (ZZO) thin films have been investigated as an anode material, a potential alternative to indium tin oxide (ITO), for organic light emitting diode (OLED) devices. ZZO films have been deposited on glass substrates by pulsed laser deposition. The electrical and optical properties of these films were studied as a function of substrate temperature and oxygen pressure during deposition. For a 200-nm-thick ZZO film grown at 250 °C in 1 mTorr of oxygen, a resistivity of 5.6×10−4 Ω cm was measured and an average optical transmittance of 84% was measured in the visible range (400–700 nm). The ZZO films, grown at different oxygen pressures, were used as an anode contact for OLED devices. External electroluminescence quantum efficiencies (0.8%–0.9%) comparable to those (0.9%–1.0%) measured for control devices fabricated on commercial ITO anodes were obtained at high current densities (1000 A/m2). These results demonstrate that ZZO is a good anode material. In addition, it is an attractive alternative to .
Electron trajectories in a model magnetosphere : simulation and observation under active conditions

Trajectories of electrons with energies of 10–2000 MeV were studied using Tsyganenko's global quantitative model of the magnetosphere. Results were compared with balloon observations of atmospheric, return albedo, and cosmic electrons made at Prince Albert on August 26, 1987. Active geomagnetic conditions were associated with unusual variations in the flux of electrons on that date, which we interpret as a manifestation of an anomalously low and highly variable geomagnetic cutoff. Increasing the ring current intensity in the Tsyganenko model reduces the calculated effective cutoff rigidity somewhat, but to explain all of our observations, we must postulate that trajectories traditionally assumed to be forbidden are sometimes systematically converted into allowed trajectories. Within this model we can also identify field lines on which bursts of auroral X rays were generated.
Dust Grains in the Comae and Tails of Sungrazing Comets: Modeling of Their Mineralogical and Morphological Properties

Abstract Observations of sungrazing comets, all of which belong to the Kreutz family, provide the opportunity of studying the properties of dust in the comae and tails of the comets. On the basis of available information on cometary and interplanetary dust as well as observations of dust in the tails of sungrazers, we model dust in sungrazing comets as fluffy silicate aggregates of submicrometer sizes. To better interpret observational data, we numerically calculate the solar radiation pressure, the equilibrium temperature, and the sublimation and crystallization rates of silicate grains near the Sun. Our results show that the dust tails contain aggregates of submicrometer crystal grains, but not amorphous grains, since amorphous silicates mostly crystallize after release from the comets. The peak in the lightcurves of the dust comae observed either at 11.2 or 12.3 solar radii (R⊙) seems to result from sublimation of fluffy aggregates consisting of crystalline or amorphous olivines, respectively. We attribute an additional enhancement in the lightcurves inside 7 R⊙ to increasing out-flow of crystalline and amorphous pyroxenes composed fluffy aggregates. According to our model, the observed lightcurves indicate a high abundance of olivine and a low abundance of pyroxene in the comets, which may bear implications about the dynamical and thermal history of the sungrazers and their progenitor.
Soft X-ray emission in Eridanus: An old supernova remnant

Data are presented on the soft X-ray intensity and spectrum of a region of extended emission in the constellation Eridanus. This region also includes optical filaments, the hard X-ray source 3U 0431--10, the radio pulsar MP 0450, a neutral hydrogen shell structure, and an O VI absorption feature. It is suggested that these features are all part of an old supernova remnant with an age in the range 10/sup 5/--10/sup 6/ yrs. (AIP)
Stability and stabilization of discrete time switched systems

This paper addresses two strategies for stabilization of discrete time linear switched systems. The first one is of open loop nature (trajectory independent) and is based on the determination of an upper bound of the minimum dwell time by means of a family of quadratic Lyapunov functions. The relevant point on dwell time calculation is that the proposed stability condition does not require the Lyapunov function be uniformly decreasing at every switching time. The second one is of closed loop nature (trajectory dependent) and is designed from the solution of what we call Lyapunov–Metzler inequalities from which the stability condition is expressed. Being non-convex, a more conservative but simpler to solve version of the Lyapunov–Metzler inequalities is provided. The theoretical results are illustrated by means of examples.
NONPARAMETRIC IDENTIFICATION OF THE MIXED HAZARDS MODEL WITH TIME-VARYING COVARIATES

Most nonparametric identification results for the mixed proportional hazards model for single spell duration data depend crucially on the proportional hazards assumption. Here, it is shown that variation in covariates over time, combined with variation across observations, is sufficient to ensure identification without the proportional hazards assumption. The required variation over time is minimal, and the mixed hazards model is identified without the proportional hazards assumption in the presence of standard time-varying covariates.Thanks to Kåre Bævre, Zhiyang Jia, Tore Schweder, Rolf Aaberge, and John K. Dagsvik for useful comments.
A MAC scheme of HORNET based on PRI and node structure with variable optical buffer

A MAC scheme of HORNET based on PRI and node structure with variable optical buffer is reported. When collision is detected in an AP, PRI of this coming packet is compared with that of the packet being transmitted, if priority of the former is low, it will be routed into a variable optical buffer to loop for the latter. If its priority is high, the buffer will be closed, and the coming packet will be transmitted undisturbedly. On the other hand, the packet being transmitted is terminated, and the transmitter sends out a jamming signal. The downstream AP recognizes the incomplete packet by the presence of the jamming signal and pulls it off the ring. The AP can reschedule the transmission of the packet for a later time. Thus it can be ensured that the packet with high PRI will be transmitted first when conflict emerges.
Imaging the host galaxies of high-redshift radio-quiet QSOs

We present new deep K-band and optical images of four radio-quiet QSOs at z approximately = 1 and six radio-quiet QSOs at z approximately = 2.5, as well as optical images only of six more at z approximately = 2.5. We have examined the images carefully for evidence of extended 'fuzz' from any putative QSO host galaxy. None of the z approximately = 2.5 QSOs shows any extended emission, and only two of the z approximately = 1 QSOs show marginal evidence for extended emission. Our 3 sigma detection limits in the K images, m(sub K) approximately = 21 for an isolated source, would correspond approximately to an unevolved L(sup star) elliptical galaxy at z = 2.5 or 2-3 mag fainter than an L(sup star) elliptical at z = 1, although our limits on host galaxy light are weaker than this due to the difficulty of separating galaxy light from QSO light. We simulate simple models of disk and elliptical host galaxies, and find that the marginal emission around the two z approximately = 1 QSOs can be explained by disks or bulges that are approximately 1-2 mag brighter than an unevolved L(sup star) galaxy in one case and approximately 1.5-2.5 mag brighter than L(sub star) in the other. For two other z approximately = 1 QSOs, we have only upper limits (L approximately = L(sup star)). The hosts of the high-redshift sample must be no brighter than about 3 mag above an unevolved L(sup star) galaxy, and are at least 1 magnitude fainter than the hosts of radio-loud QSOs at the same redshift. If the easily detected K-band light surrounding a previous sample of otherwise similar but radio-loud QSOs is starlight, then it must evolve on timescales of greater than or approximately equal to 10(exp 8) yr (e.g., Chambers & Charlot 1990); therefore our non-detection of host galaxy fuzz around radio-quiet QSOs supports the view that high-redshift radio-quiet and radio-loud QSOs inhabit different host objects, rather than being single types of objects that turn their radio emission on and off over short timescales. This is consistent with the general trend at low redshifts that radio-loud QSOs are found in giant elliptical galaxies while radio-quiet QSOs are found in less luminous disk galaxies. It also suggests that the processes responsible for the spectacular properties of radio-loud AGNs at high redshifts might not be generally relevent to the (far more numerous) radio-quiet population.
Behavioral Controllability of Delay-Differential Systems

In this paper we will prove that the system described by the delay-differential equation $R(d/dt,\Delta)w=0$ (with $\Delta$ the unit delay operator) is controllable if and only if the rank of $R(\lambda,e^{-\lambda})$ is constant for all $\lambda \in {\bkC}$. This condition is compared with the existing results obtained both by the analytic approach and by the algebraic approach to delay-differential systems.
High confinement plasmas in the Madison Symmetric Torus reversed-field pinch

Reduction of core-resonant m=1 magnetic fluctuations and improved confinement in the Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field pinch have been routinely achieved through control of the surface poloidal electric field, but it is now known that the achieved confinement has been limited in part by edge-resonant m=0 magnetic fluctuations. Now, through refined poloidal electric field control, plus control of the toroidal electric field, it is possible to reduce simultaneously the m=0 and m=1 fluctuations. This has allowed confinement of high-energy runaway electrons, possibly indicative of flux-surface restoration in the usually stochastic plasma core. The electron temperature profile steepens in the outer region of the plasma, and the central electron temperature increases substantially, reaching nearly 1.3 keV at high toroidal plasma current (500 kA). At low current (200 kA), the total beta reaches 15% with an estimated energy confinement time of 10 ms, a tenfold .
Rigorous lubrication approximation

We rigorously carry out a lubrication approximation for a liquid thin film which spreads on a solid, driven by surface tension. We consider a two-dimensional Darcy liquid as simple model case. Of particular interest to us is the codimension-two free boundary, i.e. the triple junctions where solid, liquid and vapor meet. In the considered regime of complete wetting, the contact angle vanishes throughout the evolution. We show in particular that this contact-angle condition is preserved in the lubrication approximation.
Structural and Electroluminescence Characteristics of Nonpolar Light-Emitting Diodes Fabricated on Lateral Epitaxially Overgrown a-Plane GaN

We report on the structural and electroluminescence characteristics of blue and cyan a-plane InGaN/GaN light-emitting diodes (LEDs). Cross-sectional transmission emission microscopy revealed the generation of occasional “asymmetric V-defects” in the active region. The blue and cyan LEDs exhibited rectifying behavior with forward voltages of 2.4 and 3.5 V at 20 mA, respectively and series resistances of 7 and 8 Ω, respectively. On-wafer dc output powers as high as 1.8 and 1.0 mW were measured at a drive current of 300 mA for the blue and the cyan LEDs, respectively. Electroluminescence measurement revealed an initial blue shift in the emission wavelength with the increase in the drive current. We speculate that the emission wavelength shift is due to the band-filling effect as a result of localization in the inclined non-{1120} oriented facets, which are polar in nature.