Miracle-dz/UniFAR-FTUs huggingface dataset:
On the Stopping of Fast Particles and on the Creation of Positive Electrons

The stopping power of matter for fast particles is at present believed to be due to three different processes: (1) the ionization; (2) the nuclear scattering; (3) the emission of radiation under the influence of the electric field of a nucleus. The first two processes have been treated in quantum mechanics by Bethe, Moller, and Bloch in a very satisfactory way. A provisional estimation of the order of magnitude to be expected in the third process has been given by Heitler. The result obtained was that the cross-section ϕ for the energy loss by radiation for very fast particles (if the primary energy E ≫ mc 2) is of the order ϕ ∽ Z2/137 ( e 2/ mc 2)2, (1) Where Z is the nuclear charge. It is the aim of the present paper to discuss in greater detain the rate of loss of energy by this third process and its dependence on the primary energy; in particular we shall consider the effect of screening . The results obtained for very high energies (> 137 mc 2) seem to be in disagreement with experiments made by Anderson ( cf . 7).
Harmonic Function Spaces on Groups

A class of harmonic function spaces is introduced and studied, namely the spaces Hpσ (G) of σ‐harmonic Lp functions on a locally compact group G, for 1⩽ p ⩽ ∞ and a given complex measure σ on G of unit norm. It is shown that there is a contractive projection from Lp(G) onto Hpσ (G), for 1< p⩽ ∞, and structural results for Hpσ (G) are deduced. Given an adapted probability measure σ on G, a uniqueness result is proved, that the space Hpσ (G) contains only constant functions, for 1⩽ p<∞. For any σ, a result on the dimension of H1σ (G) is proved.
Mathematical analysis of factors influencing the skin thickness of asymmetric reverse osmosis membranes

The formation of the dense surface skin of asymmetric reverse osmosis membranes is analyzed in terms of a composite process involving solvent diffusion and polymer relaxation. The analysis indicates that films with minimum skin thickness result from (i) rapid polymer relaxation; (ii) strongly concentration‐dependent solvent diffusion coefficients. The numerical results are discussed in terms of experimental variables. It indicates great difficulty in producing asymmetric films with extremely thin surface skins. The implications of this finding are discussed. Experimental NMR self‐diffusion studies of acetone in cellulose acetate are reported.
Collapse of microchannels during anodic bonding: Theory and experiments

By fabricating a large number of microchannels with different aspect ratios using anodic bonding, we demonstrate that a channel collapse can occur during anodic bonding as a result of the high electric field inside the channels. A theory is developed to establish a criterion for the collapse. This theory shows that the collapse can be avoided as long as the condition eaV2a/Eeffd3<1 is satisfied, where ea is the permittivity of air, V is the applied voltage for anodic bonding, Eeff is a material constant which characterizes the elastic stiffness of the materials, a is the half width of the channel, and d is the channel depth. The validity of this theory is checked by comparing with experimental results.
Three‐dimensional simulation of crack with curved front with direct estimation of stress intensity factors

This paper consists of an extension of simulation with direct estimation of stress intensity factors to the three‐dimensional case. Here, it combines X‐FEM with localized multigrids and direct estimation of quantities of interest along the crack front (SIF, T‐stress, etc.) based on crack tip asymptotic series expansion. In practice, a three‐dimensional patch is introduced locally with a truncated basis of Williams series expansion and is linked in a weak sense with the X‐FEM localized multigrids. Some examples (with available analytical solutions) illustrate the efficiency and the robustness of the method. These examples consider planar cracks with curved front, but the proposed method aims to apply to any continuously curved crack. Copyright © 2014 John Wiley & Sons, Ltd.
Near-infrared dye laser pumped by a carbazine-122 dye laser

Efficient generation of a high-power near-infrared dye laser has been achieved by pumping longitudinally with a 5321-A pumped carbazine-122 dye laser at 7000 A. A peak power as high as 3.5 MW at 8630 A and peak powers in excess of 0.5 MW from 7680 to 9170 A have been obtained.
Mass and Energy Flow in the Solar Chromosphere and Corona

Some results of investigations into the mass and energy flow in the solar chromosphere and corona are reviewed. The objective of these investigations is the development of a physical model that will not only account for the physical conditions in the outer atmosphere of the sun but also can be applied to the study of the chromospheres and coronae of other stars. (GHT)
Initial state perturbations in ensemble forecasting

Abstract. Due to the chaotic nature of atmospheric dynamics, numerical weather prediction systems are sensitive to errors in the initial conditions. To estimate the forecast uncertainty, forecast centres produce ensemble forecasts based on perturbed initial conditions. How to optimally perturb the initial conditions remains an open question and different methods are in use. One is the singular vector (SV) method, adapted by ECMWF, and another is the breeding vector (BV) method (previously used by NCEP). In this study we compare the two methods with a modified version of breeding vectors in a low-order dynamical system (Lorenz-63). We calculate the Empirical Orthogonal Functions (EOF) of the subspace spanned by the breeding vectors to obtain an orthogonal set of initial perturbations for the model. We will also use Normal Mode perturbations. Evaluating the results, we focus on the fastest growth of a perturbation. The results show a large improvement for the BV-EOF perturbations compared to the non-orthogonalised BV. The BV-EOF technique also shows a larger perturbation growth than the SVs of this system, except for short time-scales. The highest growth rate is found for the second BV-EOF for the long-time scale. The differences between orthogonal and non-orthogonal breeding vectors are also investigated using the ECMWF IFS-model. These results confirm the results from the Loernz-63 model regarding the dependency on orthogonalisation.
Unit Graphs Associated with Rings

Let R be a ring with nonzero identity. The unit graph of R, denoted by G(R), has its set of vertices equal to the set of all elements of R; distinct vertices x and y are adjacent if and only if x + y is a unit of R. In this article, the basic properties of G(R) are investigated and some characterization results regarding connectedness, chromatic index, diameter, girth, and planarity of G(R) are given. (These terms are defined in Definitions and Remarks 4.1, 5.1, 5.3, 5.9, and 5.13.)
Reversed Hölder Type Inequalities for Monotone Functions of Several Variables

Some reversed Hölder type inequalities yielding for monotone or quasimonotone functions of one variable have recently been obtained and applied (see e.g. [1], [2], [3], [5], [9], [12], [14], [17]). In this paper some inequalities of this type are proved for the more general case with n functions of m variables (m, n ∈ ℤ+ ). Some of these results seem to be new also for the case n = 1 or m = 1.
Second order abstract initial-boundary value problems

Introduction Partial differential equations on bounded domains of R n have traditionally been equipped with homogeneous boundary conditions (usually Dirichlet, Neumann, or Robin). However, other kinds of boundary conditions can also be considered, and for a number of concrete application it seems that dynamic (i.e., time-dependent) boundary conditions are the right ones. Motivated by physical problems, numerous partial differential equations with dynamic boundary conditions have been studied in the last decades: H.cher has investigated parabolic problems (see [Es93] and references therein); and J.T. Beale and V.N. Krasil'nikov, among others, have investigated second order hyperbolic equations with dynamical boundary conditions (see [Be76], [Kr61], [Be00], and references therein). In recent years, a systematic study of problems of this kind has been performed mainly who in a series of papers (see [FGGR02], [FGG+03], and references therein) have convincingly shown that dynamic boundary conditions are the natural L p-counterpart to the well-known (generalized) Wentzell boundary conditions. On the other side, K. -J. Engel has introduced a powerful abstract technique to handle this kind of problems, reducing them in some sense to usual, perturbed evolution equations with homogeneous, time-independent boundary conditions (see [En99], [CENN03], and [KMN03]). Both schools reduce the problem to an abstract Cauchy problem associated to an operator matrix on a suitable product space. We remark that more recently an abstract approach that in some sense unifies dynamic and static boundary value problems has been developed by G. Nickel, cf. [Ni04]. In the first chapter we introduce an abstract setting to consider what we call an abstract initial boundary value problem, i.e., a system of the form (AIBVP)            ˙ u(t) = Au(t), t ≥ 0, ˙ x(t) = Bu(t) + ˜ Bx(t), t ≥ 0, x(t) = Lu(t), t ≥ 0, u(0) = f ∈ X, x(0) = g ∈ ∂X. Here the first equation takes place on a Banach state space X (in concrete applications, this is often a space of functions on a domain Ω ⊂ R n with smooth, 1 nonempty boundary ∂Ω). The third equation represents a coupling relation between the variable in X and the variable in a Banach boundary space ∂X (in concrete applications, this is often a space of functions on ∂Ω). Finally, the second equation represents an evolution equation on the boundary with a feedback term given by the operator B. Following [KMN03, § 2], …
10‐μm absorption spectra of silicates for two new diffuse interstellar medium sightlines

We present low resolution 10-μm spectra of the newly identified diffuse interstellar medium (ISM) sightlines towards StRS 217 and StRS 371 and a new spectrum of Cyg OB2 no. 12 obtained at the UK Infrared Telescope (UKIRT) with the Michelle imager/spectrometer. As previously, the μ Cephei emissivity better represents the profile of diffuse medium silicates than does the broader Trapezium emissivity which is characteristic of dust in molecular clouds. These spectra together with seven spectra published by Roche & Aitken comprise the majority of the silicates data set for the diffuse ISM. The observed sample includes sources in the first galactic quadrant at heliocentric distances of about 1.0-4.2 kpc. We find the silicate optical depth, c sil = A V /(19.2±0.6) and the ratio of c sil to heliocentric distance, d, is in the range 0.1 <∼ c sil /d <∼ 0.7 kpc -1 ; for StRS 217 the ratio could be as high as c sil /d <∼ 1.2 kpc -1 . However, this ratio is dominated by uncertainties in the distance estimates and does not indicate the degree of clumping in the diffuse interstellar medium.
An approach for accurate GPS navigation with SA

An approach is presented for more accurate GPS navigation with selective availability. In this approach, a linearized perturbation model has been obtained. Using the measurement perturbation difference approach, the model is made suitable to formulate the Kalman filter to obtain the estimate of state perturbation and thereby the estimate of the user position and velocity. Simulation results are provided to confirm the efficacy of the approach.
Effect of Stacking Sequence on Open-Hole Tensile Strength of Composite Laminates

Theeffectofaplystackingsequenceontheopen-holetensilestrengthofcompositelaminateshasbeeninvestigated both numerically and experimentally. A finite element technique has been developed that includes the subcritical damage within and between the plies. It is thus able to capture, in some detail, the effects of variation in stacking sequence. All possible permutations of 0, 90, and 45deg plies in a quasi-isotropic layup have been analyzed. Variations in strength have been observed andexplained in terms of subcritical damage development. Two stacking sequences showing different behavior were chosen for scaling in the thickness direction by increasing the ply thickness. Analysis of the first predicted a significant decrease in strength and a change in failure mode from fiberdominated to delamination-dominated failure with increasing thickness. The second predicted no such decrease in strength or change of failure mode. Both of these stacking sequences were then tested experimentally at both thicknesses, and excellent agreement with the numerical models was obtained, both in terms of damage mode and failure stress.
On the source of dense outflows from T Tauri stars — II. Warm disc winds

Recent ultraviolet (UV) observations suggest that there is a hot (T e ≃ 80 000 K) and dense (Ne ≃ 10 10 cm -3 ) wind associated with the large-scale jets observed in classical T Tauri stars (cTTSs). The observations of these rather evolved sources cannot be fitted with the classical cold disc wind solutions. This is not unexpected since the accretion rates are moderate (≤10 -8 M ○. yr -1 ) and the wind lighter than at earlier phases. Henceforth, X-ray radiation from the star and the star-disc interaction region is expected to modify the thermal structure of the inner disc, e.g. the base of the disc wind. Thus, thermal pressure is relevant to load gas on the field lines. In this work, we analyse whether warm disc winds can account for these UV observations. To get a good hint on the physics, we have preferred to focus on analytical work. We have made use of the warm disc wind solution with pressure calculated by Vlahakis et al. The rich complexity of the magnetohydrodynamic (MHD) disc wind kinematics is analysed in detail. We show the following. (i) Warm disc flows departing from the inner disc radius (∼0.1 au) reach terminal velocities close to the observed (300 km s -1 ) and that the temperature at the base of the wind is ∼40 000 K. Thus, the spectral signature of warm disc winds is an enhancement of the chromospheric and transition region spectral indicators by several orders of magnitude, as observed in cTTSs. (ii) Warm disc winds rotate, but their rotation velocity is small since the wind dynamics is based in a transference of angular momentum from the star to the magnetic field. Henceforth, slow rotation plus high temperature (e.g. rotational broadening) show in very broad profiles at the base of the wind. (iii) The kinematics at the base of the wind is dominated by axial expansion; however, above z ≃ 5 au, the dominant kinematical component is acceleration along the disc axis. (iv) The most often observed profile is a single-peaked line, slightly blueshifted and asymmetric with a tail to short wavelengths. The full width at half-maximum is clearly suprathermal and depends on the spectral tracer used. Line profiles, fluxes and line ratios are calculated for the Civ[uvl], C III] 1908 , C II] 2326 , Si III] 1892 and [O II] 2471 UV lines. In edge-on systems, the profiles range from symmetric lines with suprathermal broadenings for the spectral tracers of the base of the wind (C IV[uv1] and Si III] 1892 ) to double-peaked profiles for spectral tracers more weighted to higher values of z ([O II] and C II]). In pole-on systems, the profiles are blueshifted (from few to 200 km s -1 ) and asymmetric exhibiting long tails towards the terminal velocity of the wind (V rad = 300 km s -1 ). To reproduce the observed line fluxes and ratios, winds must be clumpy and extinction by the flaring disc and the wind itself ought to be taken into account.
Sliding Mode Compensation and Control Based Disturbance External Force Estimation for a Piezoelectric Actuator

In this paper a sliding mode algorithm for total disturbance estimation and control of piezoelectric stack actuator is proposed. The disturbance observer is based on the lumped parameters model of mechanical motion so it allows the summary action of nonlinear hysteresis disturbance, external forces acting on the system as well as parameters variation to be estimated. Furthermore, using a nonlinear differential equation the internal hysteresis disturbance is removed from the total disturbance in an attempt to estimate the external force acting on the actuator. It is then possible to use this external force estimate as a means of observer based force control of the actuator. Simulation and experiments are compared for validating the disturbance and external force estimation technique. Experiments that incorporate disturbance compensation in a closed-loop SMC control algorithm are also presented to prove the effectiveness of this method in producing high precision motion.
Acoustic damping in langatate as a function of temperature, frequency, and mechanical contact

Resonant acoustic damping in planoconvex (trapped-mode) langatate (La/sub 3/Ga/sub 5.5/Ta/sub 0.5/O/sub 14/) disks was measured at frequencies from 2 MHz to 18 MHz and temperatures from 130 K to 450 K. A broad anelastic relaxation peak was observed in the temperature dependence of the damping, and this peak extends into the ambient temperature range. Measurements and theoretical calculations of the vibrational trapping efficiency indicate that external damping was not significant for measured overtones above the fundamental. For some modes, relatively narrow peaks in the temperature dependence of the loss were observed, and these are attributed to coupling with other modes.
Three‐dimensional transport simulations of the dispersal of volcanic aerosol from Mount Pinatubo

Three-dimensional Eulerian and Lagrangian transport simulations are used to investigate aspects of the initial dispersal of the volcanic aerosol plume from the 1991 eruption of Mount Pinatubo. A global finite-difference model that simulates the large-scale dynamics of the earth's stratosphere is combined with an Eulerian spectral transport model and a Lagrangian trajectory model. the simulated transport of the volcanic plume is compared with observations of the volcanic plume made from the SAGE II satellite instrument. Dynamical quantities, diagnosed from the simulated wind- and temperature-fields, provide insight into the evolution of the volcanic plume. Lagrangian trajectories help assess the performance of the Eulerian transport model and highlight smallscale structure that is masked by the finite resolution of the Eulerian model. Exponential material-stretching rates, symptomatic of efficient mixing, are found when air is peeled off the volcanic plume into southern mid-latitudes. On-line simulations show that radiative heating of the cloud has a major impact on its transport. Details of the local and far-field dynamical responses to the heating are discussed.
SINGLE-CRYSTAL DIAMOND PIXELATED RADIATION DETECTOR WITH BURIED GRAPHITIC ELECTRODES

A new type of transmissive pixel detector has been developed for synchrotron radiation diagnostics at Diamond Light Source. A thin single-crystal CVD diamond plate is used as the detector material, and a pulsed-laser technique has been used to write conductive graphitic electrodes inside the diamond plate. Instead of using traditional electrodes formed from a layer of surface metallisation, the graphitic electrodes are buried under the surface of the diamond and result in an all-carbon imaging detector. Within the instrument’s transmissive aperture there are no surface structures that could be damaged by exposure to radiation beams, and no surface metallization that could introduce unwanted absorption edges. The instrument has successfully been used to image the X-ray beam profile and measure the beam position to sub-micron accuracy at 100 FPS at Diamond Light Source. A novel modulation lock-in technique is used to read out all pixels simultaneously. Presented in this work are measurements of the detector’s beam position resolution and intensity resolution. Initial measurements of the instrument’s spread-function are also presented. Numerical simulations are used to identify potential improvements to the electrode geometry to improve the spatial resolution of similar future detectors. The instrument has applications in both synchrotron radiation instrumentation, where real-time monitoring of the beam profile is useful for beam diagnostics and fault-finding, and particle tracking at colliders, where the electrode geometries that buried graphitic tracks can provide increased the charge collection efficiency of the detector.
Cylindrical-wave diffraction by a rational wedge

In this paper, new expressions for the field produced by the diffraction of a cylindrical wave by a wedge, whose angle can be expressed as a rational multiple of π, are given. The solutions are expressed in terms of source terms and real integrals that represent the diffracted field. The general result obtained includes as special cases, Macdonald’s solution for diffraction by a half plane, a solution for Carslaw’s problem of diffraction by a wedge of open angle 2/3π, and a new representation for the solution of the problem of diffraction by a mixed soft-hard half plane.
Advanced tilt correction from flow distortion effects on turbulent CO2 fluxes in complex environments using large eddy simulation

Measurement of the turbulent fluxes of gases, momentum and heat can be biased by obstacles such as buildings or instrument platforms distorting the flow of air to the flux instruments. Standard methods have long been used to account for non‐horizontal mean flows. Here we demonstrate a novel approach to correct for the effects of flow distortion which combines numerical flow modelling with eddy covariance measurements of the fluxes. This approach applies a flow distortion correction to the data prior to the application of the standard planar‐fit and double‐rotation methods. This new direction‐dependent flow correction allows the determination of the correct orthogonal wind vector components and hence the vertical turbulent fluxes. We applied the method to a 10 Hz dataset of 3D wind components, temperature, and the concentrations of carbon dioxide and water vapour, as measured on top of a military tower above the city of Münster in northwest Germany during spring and summer 2007. Significant differences appeared between the fluxes that were calculated with the standard rotation methods alone and those that underwent flow distortion correction prior to the application of the rotation methods. The highest deviations of 27% were obtained for the momentum flux. Pronounced differences of 15% and 8% were found for the diurnal net fluxes of carbon dioxide and water vapour, respectively. The flow distortion correction for the carbon dioxide fluxes yielded the same magnitude as the WPL (Webb–Pearman–Leuning) correction for density fluctuations. Copyright © 2009 Royal Meteorological Society
Filtering on sampled-data systems with parametric uncertainty

The paper is concerned with the problem of robust H/sub /spl infin// filtering for a class of systems with parametric uncertainties and unknown time delays under sampled measurements. The parameter uncertainties considered are real time-varying and norm-bounded, appearing in the state equation. An approach has been proposed for the designing of H/sub /spl infin// filters, using sampled measurements, which would guarantee a prescribed H/sub /spl infin// performance in the continuous-time context, irrespective of the parameter uncertainties and unknown time delays. Both cases of finite and infinite horizon filtering are studied. It has been shown that the above robust H/sub /spl infin//-filtering problem can be solved in terms of differential Riccati inequalities with finite discrete jumps.