Miracle-dz/UniFAR-FTUs huggingface dataset:
MEASUREMENT OF SNOW PARAMETERS BY RADAR

Abstract According to Rayleigh scattering theory for small spheres, back scattering is proportional to |K2Z where K is the dielectric factor and Z is the sum of the sixth powers of the diameter D. For small non-spherical particles of uncertain density, a similar quantity can be used: |K12ZS, where K1 is the dielectric factor for the material when reduced to unit density, and Z = ∑D16, where D1 is the diameter of the particle when reduced to a sphere of unit density; S is a shape factor which for snow remains between 1 and 1.5. An analysis of Langille and Thain's (1951) radar observations on snow shows fairly good correlation between Z and the snowfall R, particularly when considered one day at a time. An overall Z = Z(R) relation for snow for all days of Langille's observations is found to agree with that previously established for rain (Marshall, Langille and Palmer, 1947). That is, equal precipitation rates R, whether rain or snow, give equal values of Z. The transition at the melting level in the case .
Coherent magnetization reversal of nanoparticles with crystal and shape anisotropy

We discuss coherent magnetization reversal in single-domain particles with cubic or uniaxial crystal anisotropy and present the derivation and simulation of the nucleation field in the important case of particles with shape anisotropy and a random orientation of a cubic crystal anisotropy axis. We analyze the interplay of shape and crystal anisotropy as a function of crystal orientation with respect to the applied field. In addition, we present simulations for particles with uniaxial crystal anisotropy and derive the values for remanence and coercive field of an ensemble of particles from calculated hysteresis loops in each case.
Analysis of Means Using Ranks

A nonparametric procedure, called the analysis of means using ranks (ANOMR), is proposed for testing the equality of several population means. The ANOMR procedure may be used graphically in the form of a Shewhart control chart and so has the advantage of pinpointing which population mean, if any, is significantly different from the others. Exact and asymptotic critical values are given for the implementation of ANOMR. Results from a Monte Carlo power study are presented which indicate that for light-tailed distributions such as the uniform and the normal, ANOMR is only slightly less powerful than the parametric competitive procedures based on analysis of variance and analysis of means. For heavy-tailed distributions such as the Cauchy, ANOMR is shown to provide greater power than the parametric procedures. The results also indicate that for both light and heavy-tailed distributions the use of the ANOMR test instead of the Kruskal-Wallis test leads to only a small loss of power for a range of alternatives.
Examination of a Stochastic and Deterministic Convection Parameterization in the COSMO Model

AbstractStochastic parameterizations allow the representation of the small-scale variability of parameterized physical processes. This study investigates whether additional variability introduced by a stochastic convection parameterization leads to improvements in the precipitation forecasts. Forecasts are calculated with two different ensembles: one considering large-scale and convective variability with the stochastic Plant–Craig convection parameterization and one considering only large-scale variability with the standard Tiedtke convection parameterization. The forecast quality of both ensembles is evaluated in comparison with radar observations for two case studies with weak and strong synoptic forcing of convection and measured with neighborhood and probabilistic verification methods. The skill of the ensemble based on the Plant–Craig convection parameterization relative to the ensemble with the Tiedtke parameterization strongly depends on the synoptic situation in which convection occurs. In the we.
Low-threshold organic laser based on an oligofluorene truxene with low optical losses

A blue-emitting distributed feedback laser based on a star-shaped oligofluorene truxene molecule is presented. The gain, loss, refractive index, and (lack of) anisotropy are measured by amplified spontaneous emission and variable-angle ellipsometry. The waveguide losses are very low for an organic semiconductor gain medium, particularly for a neat film. The results suggest that truxenes are promising for reducing loss, a key parameter in the operation of organic semiconductor lasers. Distributed feedback lasers fabricated from solution by spin-coating show a low lasing threshold of 270 W/cm2 and broad tunability across 25 nm in the blue part of the spectrum.
Resolution of Curvature Singularities in Black Holes and the Early Universe

This thesis is concerned with two approaches on the singularity problem of the general theory of relativity. The first is of bottom-up nature. We start from Einstein's well established general relativity and make an educated guess for an asymptotically equivalent but non-singular theory. In the second approach we take the top-down perspective starting with the assumption that string theory gives the fundamental description of nature and analyse the resulting low energy effective theory. Our bottom-up approach is an application of the limiting curvature hypothesis to anisotropic cosmologies. This extends the success for isotropic cosmologies of Brandenberger et al. Applying the LCH, they constructed a theory in which all homogeneous and isotropic solutions are singularity free. Due to the non-analytic nature of the equations we were unable repeat the proof in the anisotropic case, but analytical and numerical analysis produce circumstantial evidence for a resolution of the singularity in this case as well. Generically this resolution seems not to involve a de Sitter phase as expected. Instead it would interpolate between a contracting anisotropic universe and a universe, that time-symmetrically expands anisotropically. During this transition spacetime evolves through a nearly flat, Minkowski phase. This solution could represent an alternative to the so-called bounce solutions as they appear in pre-big-bang scenarios. In our top-down approach we construct a simple model in type IIA super string theory. With a non-BPS D7 or D9 brane we introduce a tachyonic degree of freedom. Its potential is influenced by the compact background wrapped by the brane. In a way the mass can be tuned by the size of the compact dimension. We use a truncated action which was constructed in order to approximate the full string theory result for the dynamical creation and decay of non-BPS branes quite accurately. Taking the lowest order effective action for metric, dilaton and an effective action for the open tachyonic mode, we obtaine bounce solutions. The bounce results from the positivity of the pressure of the tachyon field in our Lagrangian. Both curvature and time derivative of the dilaton remain small during our bounce so that the gravitational sector behaves entirely classical. Asymptotically our bounce solutions are similar to pre-big bang and post-big bang solutions respectively. Thus there remain singularities in the curvature and the dilaton before or after the bounce. These asymptotic string frame curvature singularities can be resolved by the ad hoc addition of a potential term, that might result from alpha' corrections in the open string sector. Exact calculation of the corrections would be necessary in order to give a more precise picture.
ON THE POSSIBILITY OF OUTFLOWS FROM VERY LOW MASS COMPANIONS

High-velocity outflows, once thought to be possible only for massive pre-main-sequence stars, have been found associated with sources of less than solar mass. The possibility that even much smaller objects may, at some stage of their early lives, drive such outflows is investigated. The predicted properties of outflows from these low-mass objects are such that they would be very difficult to detect directly. If, however, the low-mass source is the companion of a larger star the outflow may have interesting and possibly detectable effects on the development of the combined system.
Observations of field-aligned density fluctuations in the inner solar wind

This paper reports the results of radio wave scattering observations which show highly anisotropic density microstructure in the inner solar wind. These observations were made in October 1983 and 1985, using the National Radio Astronomy Observatory's Very Large Array. Heliocentric distances of the observations ranged from 2.2. to about 13 solar radii. The axial ratio of the density fluctuations, projected onto the plane of the sky, increased from about 4 at 10 solar radii to about 14 at 2.2 solar radii. The major axis appeared to be field aligned; that is, the irregularities were stretched out approximately along the radial. These results are, in general, consistent with the results of earlier observations. The present observations differ in that they were taken closer to the sun, they were sensitive to larger scale structures (up to about 35 km), and showed much higher anisotropy. Combining these data with previously taken data strongly indicates that the anisotropy is scale dependent; scales greater than 10 km appear to be more anisotropic than those less than 2 km. 22 refs.
Cointegration and Dynamic Simultaneous Equations Model

The author demonstrates that despite variables that are integrated, the fundamental issues on structural equation modeling raised by the Cowles Commission remain valid and standard estimation and testing procedures can still be applied. A basic framework linking the multiple time series model and the dynamic simultaneous equation model is provided and implications under the long-run cointegrating relations are discussed. Conditions for identifying both the short-run dynamics and long-run equilibrium conditions are given. Limiting properties of the least squares and simultaneous equation estimators under cointegration are derived. Implications for hypothesis testing are also discussed.
Nets of subgroups and amenability

We first investigate some convergence properties of nets in the topological space of closed subgroups of a locally compact group. We then use these properties to answer some questions concerning the amenable subgroups. Introduction. Let G be a locally compact group and 3C(G) the set of all closed subgroups of G equipped with the compact-open topology (see ? 1 for the definition). If H is a closed (resp. closed normal) subgroup of G, then there is a canonical correspondence between the elements of 3C(G) contained in (resp. containing) H and the elements of SC(H) (resp. 3(G/H)). In ? 2 we show these are homeomorphisms. We then give necessary and sufficient conditions for a net in 3C(G) directed by set containment (resp. inclusion) to converge to G (resp. the trivial subgroup). In ? 3 we consider the collection of groups in 3C(G) which are amenable. We give sufficient conditions for the limit of a net of amenable subgroups to be amenable and another condition which is equivalent to amenability of G. Finally, if G is not amenable, then it does not contain a largest amenable subgroup; however, it does contain a maximal one. 1. Preliminaries. Recall [5, p. 427] that a basic open subset in the compact-open topology of X(G) is of the form 9U(C, 5) = { K 3C(G): Kn(CC=0, KC'B$0, for each B C}, where C is a compact subset of G and 5Z is a finite family of nonempty open subsets of G. (Note that C and 9 may be empty.) With this topology, 3C(G) is a compact Hausdorff space. Let S(G) denote the space of subgroup representations of G, i.e. pairs (K, T) where KC3C(G) and T is a (unitary equivalence class of a) unitary representation of K. We assume 8(G) to be equipped with its usual inner hull-kernel topology [5, p. 249]. E will denote the trivial subgroup { e } of G and 1 its identity representation (it is also the regular representation). Let R (resp. I) denote the regular (resp. identity) representation of G. If {K,} is a net in X(G), Ii (resp. Rj) will denote the identity (resp. regular) representation of Ki. If H, KC 3C(G) with KDH and T a representaReceived by the editors July 20, 1970. AMS 1970 subject classifications. Primary 22D05; Secondary 22D10, 22D30.
Dark current in quantum well infrared photodetectors

Modeling the dark current in quantum well infrared photodetectors has been a topic of much recent research, but the implications of many of the underlying assumptions have not been clarified. We attempt to justify one such model and to provide physical insight for its success. We compare the dark current expression with experiments on several samples, and show that the model provides a good approximation for a wide range of device parameters including barrier thicknesses from 250 to 700 A and number of wells from 4 to 32.
The Shape of the H i Mass Function for Late-Type Galaxies over the Range M H I 10 7--10 10 M sub sun

An analysis of two large catalogs of H I observations of nearby galaxies (Fisher & Tully and Hoffman et al.) does not yield evidence for either (1) a sharp rise in the number of low-mass- H I-rich objects relative to the number of large late-type galaxies or (2) a severe deficit of low-mass H I-rich objects. There may be a difference between the Virgo Cluster environment and the general field in the sense that the field is richer in small H I masses relative to the density of large galaxies, but a large uncertainty remains in determinations of the number density of objects with H I masses less than 10 7 M ○.
Time delay estimation using phase data

The estimation of time delays between two received signals using phase measurements is discussed and the accuracy of such estimates is detailed. For the ideal case of statistically independent noise and no scattering at the receiver locations, it is shown that phase data regression lines yield time delay estimates with the same accuracy as other optimal time delay estimation procedures. For less ideal situations, the potential advantages of time delay estimation using phase data are discussed and illustrated. It is shown that regression analysis of phase estimates at properly selected frequencies can sometimes be employed to reduce bias errors in time delay estimates due to correlated receiver noise. It is also shown that the estimation errors due to scattering at the receiver location can often be assessed in nonparametric terms to provide time delay estimates with a realistic error bound.
Shrinkage/Swelling Behavior of Knitted Fabrics during Relative Humidity Cycles Determined by X-ray Imaging

The 2D deformation of knitted jersey ready-to-wear clothing made of cotton was measured during adsorption and desorption steps. A digital x-ray imaging system was coupled with a climatic chamber to control temperature and relative humidity during the cycle. Images of the samples were recorded at each different equilibrium state of the cycle. Finally, an image correlation process was used to compare the recorded images and to determine the 2D strain. The deformations along course (ecc) and wale (eww) directions and the shear (ewc) were measured for four identical samples. The repeatability of the results shows the reproducibility of the measurement process. These original experimental results establish a clear anisotropic shrinkage and swelling behavior between the wale and course directions. The anisotropic ratio (ecc/eww) rises up to 2 during the adsorption step. Moreover, they enlighten a hysteresis between the adsorption and desorption steps. It denotes the effect of the material's history and it is explained by geometrical considerations of the structure at the microscopic level and the relationship with the manufacturing process. Finally, the shear strain is explained at the microscopic level by electronic microscopy (ESEM) observations that show the fibers' twist dissymmetry between the two wings of the stitch.
Stress gradient balance layers and scale hierarchies in wall-bounded turbulent flows

Steady Couette and pressure-driven turbulent channel flows have large regions in which the gradients of the viscous and Reynolds stresses are approximately in balance (stress gradient balance regions). In the case of Couette flow, this region occupies the entire channel. Moreover, the relevant features of pressure-driven channel flow throughout the channel can be obtained from those of Couette flow by a simple transformation. It is shown that stress gradient balance regions are characterized by an intrinsic hierarchy of ‘scaling layers’ (analogous to the inner and outer domains), filling out the stress gradient balance region except for locations near the wall. The spatial extent of each scaling layer is found asymptotically to be proportional to its distance from the wall. There is a rigorous connection between the scaling hierarchy and the mean velocity profile. This connection is through a certain function $A(y^+)$ defined in terms of the hierarchy, which remains $O(1)$ for all $y^+$. The mean velocity satisfies an exact logarithmic growth law in an interval of the hierarchy if and only if $A$ is constant. Although $A$ is generally not constant in any such interval, it is arguably almost constant under certain circumstances in some regions. These results are obtained completely independently of classical inner/outer/overlap scaling arguments, which require more restrictive assumptions. The possible physical implications of these theoretical results are discussed.
IDENTIFICATION OF A FLUID CATALYTIC CRACKING UNIT BY MEANS OF A NEW MULTI-VARIABLE HAMMERSTEIN MODEL

Abstract Recently, a new formulation of a multi-variable Hammerstein model has been proposed, which preserves the concept of a nonlinear static element cascaded by an independent linear dynamic element known from scalar Hammerstein models. We apply this model to the identification of a simulated fluid catalytic cracking unit (FCC) demonstrating the need for representing input-directional dynamics as well as nonlinear coupling of input variables in block-oriented chemical process modeling. Because of the preserved independence of the nonlinear and linear elements the model allows for physically meaningful intermediate variables, which facilitates the incorporation of rigorous models as well as arbitrary approximations thereof. The superiority of two such approximations, namely sparse grid and neural network representations over the classical polynomial representation is also demonstrated.
Poisson Approximation for Dependent Trials

by a Poisson distribution and a derivation of a bound on the distance between the distribution of W and the Poisson distribution with mean E(W ). This new method is based on previous work by C. Stein where a central limit theorem for a sum of dependent random variables was obtained without the use of moment generating functions. In Chen (1975), the distance between the distribution of W and the Poisson distribution is assessed based the unique solution for an equation formulated specifically for the Poisson distribution. The focus of this work is on deriving upper and lower bounds on the distance between the distribution of W and the Poisson distribution with mean E(W ). The Poisson approximation itself has been used in several ares of probability and statistics including: DNA and protein sequences, geometrical probability, spatial statistics and reliability theory. Since the Poisson approximation can be inaccurate, improvements of the Poisson approximations have been investigated. Most importantly, a compound Poisson approximation method was developed that includes a bound on the distance between the distribution of W and the approximating compound Poisson approximation. The origin of this approach is included in the Chen (1975) article.
Light absorbing particles and snow aging feedback enhances albedo reduction on the Southwest Greenland ice sheet

Greenland’s ice sheet mass loss rate has tripled since the mid-1950s in concert with sharply lowered albedo leading 10 to increased absorption of solar radiation and enhanced surface melt. Snow and ice melt driven by solar absorption is enhanced by the presence of light absorbing particles (LAPs), such as black carbon (BC) and dust. Yet, the LAP impact on melt is poorly constrained, partly due to scarce availability of in-situ measurements. Here, we present a survey of snow properties and LAPs deposited in winter snow layers at five sites in southwest Greenland collected in May 2017. At these sites, BC and dust concentrations were 0.62 ± 0.35 ng g-1 and 2.09 ± 1.60 µg g-1, respectively. By applying the SNICAR model, we show the 15 LAP influence on albedo through the combined effect of surface darkening and snow metamorphism. While the LAP concentrations are low, they result in a 1.7% and 3.0% reduction in albedo within the visible spectrum for spring and summer, respectively. Past studies have shown that even minor LAP induced albedo reductions, if widespread, can have a large impact on the overall surface mass balance. SNICAR simulations constrained by our measurements show that LAP-snow aging feedback reduce albedo reduction 4 to 10 times more than previously thought, therefore LAPs are likely a significant 20 contributor to Greenland's accelerated mass loss. As far as we know, this is the first field study to consider the LAP impact on snow aging on the Greenland ice sheet.
Magnetic Field Structure in Protostellar Envelopes

We have imaged the linearly polarized emission toward the young stellar objects NGC 1333/IRAS 4A and IRAS 16293-2422. We suggest that the polarized emission from the dense protostellar environment arises from magnetically aligned dust grains and use these observations to investigate the magnetic field structure. The observations were obtained using the new polarimetric capabilities at 3 mm of the six-element millimeter array of the Owens Valley Radio Observatory. Toward IRAS 4A, the average polarization observed is 4.4% ± 0.7%. The magnetic field direction implied by the observations is roughly parallel to the direction of the bipolar molecular outflow. Structure is seen at 3'' resolution in the linearly polarized image. The peak of the linear polarization is offset 1. ″5 from the peak of the total intensity and elongated perpendicular to the implied field direction. Models calculated with an hourglass magnetic field morphology in a spherically symmetric dusty envelope are consistent with the observations. Toward IRAS 16293 the polarized emission is located between the two binary components, and the polarization percentage at the peak of the polarized emission is 2.7% ± 0.7%. The magnetic field direction implied from our measurements is parallel to the major axis of the circumbinary disk. The polarized emission could be produced by a toroidal magnetic field in the circumbinary disk. The high resolution of the interferometer provides a probe of the polarized emission at the high densities (n ≥ 108 cm-3) characteristic of protostellar envelopes and disks. The detection of polarized emission at these densities provides a test of grain alignment mechanisms. We conclude that alignment by paramagnetic relaxation of thermally rotating grains is unlikely, because of the well-coupled gas and grain temperatures, but alignment of suprathermally rotating grains is not ruled out.