Miracle-dz/UniFAR-FTUs huggingface dataset:
Attenuated Superconductors I. For Measuring Infra‐Red Radiation

An apparatus for measuring infra‐red radiation has been constructed of fine tantalum wire, operating at a temperature of 3.22–3.23°K in the transition zone between superconduction and normal conduction. The tantalum coil is mounted on a thermostated plate with temperature electrically controlled and operates in a special self‐regulating shunt circuit by which its own temperature is automatically maintained constant. The ratio of developed electrical potential to radiation flux received is 150 μv (erg cm−2 sec.−1)−1. Minimum detectable flux is ca. 10−3 erg sec. −1. Absolute measurements of intensity of radiation from sources at temperatures between 24° and 55° are consistent with the Stefan‐Boltzmann law showing that instrument corrections for reflectivity, window‐absorption, and changes with wave‐length are very small.
Application of a Signal Technique to the Source–Receptor Relationship in Three-Dimensional Tracer Simulations

Abstract Identifying pollutant sources that contribute to downstream locations is important for policy making and air-quality control. In this study, a computationally economic signal technique was implemented into a three-dimensional nonhydrostatic atmospheric model to help to identify source–receptor relationships. An idealized supercell case and a semireal air-pollution case in Turkey were used to investigate the potential of the technique. For each pollutant, signals with various frequencies were emitted from different source locations and added into that particular type of emitted pollutants. The time series of pollutant concentration collected at receptors were then projected onto frequency space using the Fourier transform and short-time Fourier transform methods to identify the source locations. During the model integration, a particular tracer was also emitted from each pollutant source location (i.e., a conventional method to study the source–receptor relationship) to validate and evaluate the s.
The maximal jump and local convergence of continuous-state branching processes

We study the distribution of the maximal jump of continuous-state branching processes. Several exact expressions and explicit asymptotics of both the local maximal jump and the global maximal jump are obtained. We also compare the distribution of the maximal jump and the L\'{e}vy measure to get several absolute continuity results. Then we study local convergence of continuous-state branching processes under various conditionings. We obtain complete results under the conditioning of large maximal jump, and partial results under two other conditionings, which are, the conditioning of large width, and, the conditioning of large total mass.
High pressure study of graphitization of diamond crystals

Graphitization of {100} and {111} faces of diamond crystals at pressures of 0.1 and 2 GPa and various temperatures was studied by Raman spectroscopy, x-ray single crystal diffractometry, and scanning electron microscopy. Different primary mechanisms of graphitization are discussed: (a) normal growth of graphite layer by detachment of single atoms from {100} and {111} diamond surfaces and (b) lateral growth of graphite on the {111} surface by breaking off groups of atoms followed by their rearrangement into planar graphitic structures. The growth of oriented graphite crystallites was observed only on the {111} diamond faces and at p=2 GPa. In the case of synthetic diamonds, internal graphitization was observed and explained in terms of catalytic effects on the metal inclusions.
GeV telescopes: results and prospects for Fermi

We present a review of the current status and future prospects of the field of high-energy gamma-ray astrophysics in the 30 MeV to 30 GeV regime. Scientific studies in this energy range are carried out by satellite-based gamma-ray instruments. We have now entered a new era in space-based gamma-ray astrophysics with the operation of AGILE and the Fermi Gamma Ray Space Telescope. We summarize here highlights from earlier experiments such as the EGRET on board the Compton Gamma Ray Observatory and describe some of the first results from AGILE and Fermi.
Moment dynamics for a class of time-triggered stochastic hybrid systems

Stochastic Hybrid Systems (SHS) constitute an important class of mathematical models that integrate discrete stochastic events with continuous dynamics. The time evolution of statistical moments is generally not closed for SHS, in the sense that the time derivative of the lower-order moments depends on higher-order moments. Here, we identify an important class of SHS where moment dynamics is automatically closed, and hence moments can be computed exactly by solving a system of coupled differential equations. This class is referred to as linear time-triggered SHS (TTSHS), where the state evolves according to a linear dynamical system. Stochastic events occur at discrete times and the intervals between them are independent random variables that follow a general class of probability distributions. Moreover, whenever the event occurs, the state of the SHS changes randomly based on a probability distribution. Our approach relies on embedding a Markov chain based on phase-type processes to model timing of events, and showing that the resulting system has closed moment dynamics. Interestingly, we identify a subclass of linear TTSHS, where the first and second-order moments depend only on the mean time interval between events and invariant of their higher-order statistics. Finally, we discuss applicability of our results to different application areas such as network control systems and systems biology.
Approximation Schemes for Viscosity Solutions of Fully Nonlinear Stochastic Partial Differential Equations

Abstract: The aim of this paper is to develop a general method for constructing approximation schemes for viscosity solutions of fully nonlinear pathwise stochastic partial differential equations, and for proving their convergence. Our results apply to approximations such as explicit finite difference schemes and Trotter-Kato type mixing formulas. The irregular time dependence disrupts the usual methods from the classical viscosity theory for creating schemes that are both monotone and convergent, an obstacle that cannot be overcome by incorporating higher order correction terms, as is done for numerical approximations of stochastic or rough ordinary differential equations. The novelty here is to regularize those driving paths with non-trivial quadratic variation in order to guarantee both monotonicity and convergence.
Superiorization of Preconditioned Conjugate Gradient Algorithms for Tomographic Image Reconstruction

Properties of Superiorized Preconditioned Conjugate Gradient (SupPCG) algorithms in image reconstruction from projections are examined. Least squares (LS) is usually chosen for measuring data-inconsistency in these inverse problems. Preconditioned Conjugate Gradient algorithms are fast methods for finding an LS solution. However, for ill-posed problems, such as image reconstruction, an LS solution may not provide good image quality. This can be taken care of by superiorization. A superiorized algorithm leads to images with the value of a secondary criterion (a merit function such as the total variation) improved as compared to images with similar data-inconsistency obtained by the algorithm without superiorization. Numerical experimentation shows that SupPCG can lead to high-quality reconstructions within a remarkably short time. A theoretical analysis is also provided.
Spherically symmetric problem on the brane and galactic rotation curves

We investigate the braneworld model with induced gravity to clarify the role of the crossover length scale l in the possible explanation of the dark-matter phenomenon in astrophysics and in cosmology. Observations of the 21 cm line from neutral hydrogen clouds in spiral galaxies reveal that the rotational velocities remain nearly constant at a value {upsilon}{sub c}{approx}10{sup -3}-10{sup -4} in the units of the speed of light in the region of the galactic halo. Using the smallness of {upsilon}{sub c}, we develop a perturbative scheme for reconstructing the metric in a galactic halo. In the leading order of expansion in {upsilon}{sub c}, at the distances r > or approx. {upsilon}{sub c}l, our result reproduces that obtained in the Randall-Sundrum braneworld model. This inequality is satisfied in a real spiral galaxy such as our Milky Way for distances r{approx}3 kpc, at which the rotational velocity curve becomes flat, {upsilon}{sub c}{approx}7x10{sup -4}, if l < or approx. 2 Mpc. The gravitational situation in this case can be approximately described by the Einstein equations with the so-called Weyl fluid playing the role of dark matter. In the region near the gravitating body, we derive a closed system of equations for the static sphericallymore » symmetric situation under the approximation of zero anisotropic stress of the Weyl fluid. We find the Schwarzschild metric to be an approximate vacuum solution of these equations at distances r < or approx. a {radical}r{sub g}l{sup 2}). The value l < or approx. 2 Mpc complies well with the solar system tests. At the same time, in cosmology, a low-density braneworld with l of this order of magnitude can mimic the expansion properties of the high-density {lambda}+cold dark matter (LCDM) universe at late times. Combined observations of galactic rotation curves and gravitational lensing can possibly discriminate between the higher-dimensional effects and dark matter. « less
The quest for solvable multistate Landau-Zener models

Recently, integrability conditions (ICs) in mutistate Landau-Zener (MLZ) theory were proposed []. They describe common properties of all known solved systems with linearly time-dependent Hamiltonians. Here we show that ICs enable efficient computer assisted search for new solvable MLZ models that span complexity range from several interacting states to mesoscopic systems with many-body dynamics and combinatorially large phase space. This diversity suggests that nontrivial solvable MLZ models are numerous. In addition, we refine the formulation of ICs and extend the class of solvable systems to models with points of multiple diabatic level crossing.
Quasiflats in hierarchically hyperbolic spaces

The rank of a hierarchically hyperbolic space is the maximal number of unbounded factors of standard product regions; this coincides with the maximal dimension of a quasiflat for hierarchically hyperbolic groups. Noteworthy examples where the rank coincides with familiar quantities include: the dimension of maximal Dehn twist flats for mapping class groups, the maximal rank of a free abelian subgroup for right-angled Coxeter groups and right-angled Artin groups (in the latter this coincides with the clique number of the defining graph), and, for the Weil-Petersson metric the rank is half the complex dimension of Teichmuller space. We prove that in a HHS, any quasiflat of dimension equal to the rank lies within finite distance of a union of standard orthants (under a very mild condition satisfied by all natural examples). This resolves outstanding conjectures when applied to a number of different groups and spaces. The mapping class group case resolves a conjecture of Farb, in Teichmuller space this resolves a question of Brock, and in the context of CAT(0) cubical groups it strengthens previous results (so as to handle, for example, the right-angled Coxeter case). An important ingredient, is our proof that the hull of any finite set in an HHS is quasi-isometric to a cube complex of dimension equal to the rank. We deduce a number of applications; for instance we show that any quasi-isometry between HHS induces a quasi-isometry between certain simpler HHS. This allows one, for example, to distinguish quasi-isometry classes of right-angled Artin/Coxeter groups. Another application is that our tools, in many cases, allow one to reduce the problem of quasi-isometric rigidity for a given HHG to a combinatorial problem. As a template, we give a new proof of quasi-isometric rigidity of mapping class groups, using simpler combinatorial arguments than in previous proofs.
Control of a Transitioning Boundary Layer using Surface-Mounted Electro Active Polymers

Micro air vehicles (MAV) are a major focus of aerodynamics today with many military as well as civilian applications. MAV flight is dominated by the unsteady characteristics of low Reynolds number flows. Three-dimensional separations may occur at random on different parts of the wing, causing highly unsteady forces and moments, as well as full wing stall. In the present work an Electro-Active Polymer (EAP) actuator was examined as a feasible flow control actuator with application to low Reynolds number flows. The performance of the EAP was evaluated using a laser displacement device, where the displacements generated under selected driving frequencies and input voltages were recorded. It was shown that the deflections could reach up to 0.35 mm at frequencies below 40 Hz. The surface deflection was found to be parabolic across the span and width of the actuator. Hot-wire anemometry measurements were conducted on a flat plate equipped with a trailing edge flap in a low Reynolds number wind tunnel to study t.
Geometric foundations for scaling-rotation statistics on symmetric positive definite matrices: Minimal smooth scaling-rotation curves in low dimensions

We investigate a geometric computational framework, called the "scaling-rotation framework", on ${\rm Sym}^+(p)$, the set of $p \times p$ symmetric positive-definite (SPD) matrices. The purpose of our study is to lay geometric foundations for statistical analysis of SPD matrices, in situations in which eigenstructure is of fundamental importance, for example diffusion-tensor imaging (DTI). Eigen-decomposition, upon which the scaling-rotation framework is based, determines both a stratification of ${\rm Sym}^+(p)$, defined by eigenvalue multiplicities, and fibers of the "eigen-composition" map $SO(p)\times{\rm Diag}^+(p)\to{\rm Sym}^+(p)$. This leads to the notion of scaling-rotation distance [Jung et al. (2015)], a measure of the minimal amount of scaling and rotation needed to transform an SPD matrix, $X,$ into another, $Y,$ by a smooth curve in ${\rm Sym}^+(p)$. Our main goal in this paper is the systematic characterization and analysis of minimal smooth scaling-rotation (MSSR) curves, images in ${\rm Sym}^+(p)$ of minimal-length geodesics connecting two fibers in the "upstairs" space $SO(p)\times{\rm Diag}^+(p)$. The length of such a geodesic connecting the fibers over $X$ and $Y$ is what we define to be the scaling-rotation distance from $X$ to $Y. $ For the important low-dimensional case $p = 3$ (the home of DTI), we find new explicit formulas for MSSR curves and for the scaling-rotation distance, and identify ${\cal M}(X,Y)$ in all "nontrivial" cases. The quaternionic representation of $SO(3)$ is used in these computations. We also provide closed-form expressions for scaling-rotation distance and MSSR curves for the case $p = 2$.
Rational string topology

We use the computational power of rational homotopy theory to provide an explicit cochain model for the loop product and the string bracket of a 1-connected closed manifold $M$. We prove that the loop homology of $M$ is isomorphic to the Hochschild cohomology of the cochain algebra $C^\ast(M)$ with coefficients in itself. Some explicit computations of the loop product and the string bracket are given.
A Study of Options for the Deployment of Large Fusion Power Plants

One option for making fusion power plants that could be competitive with other power plants operating during the 21st century is to make them large, e.g., 3 GW(electric) or more, to take advantage of the expected economies of scale. This study examines the effects on electrical utility system hardware, operations, and reliability of incorporating such large generating units. In addition, the study evaluates the use of the coproduction of hydrogen to reduce the grid-supplied electricity and offer the possibility for electrical load-following. The estimated additional cost of electricity (COE) for a large power plant is ~5 mills/kW⋅h. The estimated total COE for 3- to 4-GW(electric) fusion power plants lies in the range of 37 to 60 mills/kW⋅h. Future hydrogen costs from a variety of sources are estimated to lie in the range of 8 to 10 $/GJ, when allowance is made for some increase in natural gas price and for the possible need for greenhouse gas emission limitations. A number of combinations of fusion plant and electrolyzer were considered, including hot electrolyzers that use heat from the fusion plant. For the optimum cases, hydrogen produced from off-peak power from a 3- to 4-GW(electric) plant is estimated to have a competitive cost. Of particular interest, the cost would also be competitive if some hydrogen were produced during on-peak electricity cost periods. Thus, for a 4-GW(electric) plant, only up to 3 GW(electric) might be supplied to the grid, and load-following would be possible, which would be a benefit to the utility system.
A strictly commutative model for the cochain algebra of a space

Abstract The commutative differential graded algebra $A_{\mathrm {PL}}(X)$ of polynomial forms on a simplicial set $X$ is a crucial tool in rational homotopy theory. In this note, we construct an integral version $A^{\mathcal {I}}(X)$ of $A_{\mathrm {PL}}(X)$. Our approach uses diagrams of chain complexes indexed by the category of finite sets and injections $\mathcal {I}$ to model $E_{\infty }$ differential graded algebras (dga) by strictly commutative objects, called commutative $\mathcal {I}$-dgas. We define a functor $A^{\mathcal {I}}$ from simplicial sets to commutative $\mathcal {I}$-dgas and show that it is a commutative lift of the usual cochain algebra functor. In particular, it gives rise to a new construction of the $E_{\infty }$ dga of cochains. The functor $A^{\mathcal {I}}$ shares many properties of $A_{\mathrm {PL}}$, and can be viewed as a generalization of $A_{\mathrm {PL}}$ that works over arbitrary commutative ground rings. Working over the integers, a theorem by Mandell implies that $A^{\mathcal {I}}(X)$ determines the homotopy type of $X$ when $X$ is a nilpotent space of finite type.
Nonlinear optimization in Hilbert space using Sobolev gradients with applications

The problem of finding roots or solutions of a nonlinear partial differential equation may be formulated as the problem of minimizing a sum of squared residuals. One then defines an evolution equation so that in the asymptotic limit a minimizer, and often a solution of the PDE, is obtained. The corresponding discretized nonlinear least squares problem is an often met problem in the field of numerical optimization, and thus there exist a wide variety of methods for solving such problems. We review here Newton's method from nonlinear optimization both in a discrete and continuous setting and present results of a similar nature for the Levernberg-Marquardt method. We apply these results to the Ginzburg-Landau model of superconductivity.
Multifractal analysis of Birkhoff averages for typical infinitely generated self-affine sets

We develop a thermodynamic formalism for quasi-multiplicative potentials on a countable symbolic space and apply these results to the dimension theory of infinitely generated self-affine sets. The first application is a generalisation of Falconer's dimension formula to include typical infinitely generated self-affine sets and show the existence of an ergodic invariant measure of full dimension whenever the pressure function has a root. Considering the multifractal analysis of Birkhoff averages of general potentials $\Phi$ taking values in $\R^{\N}$, we give a formula for the Hausdorff dimension of $J_\Phi(\alpha)$, the $\alpha$-level set of the Birkhoff average, on a typical infinitely generated self-affine set. We also show that for bounded potentials $\Phi$, the Hausdorff dimension of $J_\Phi(\alpha)$ is given by the maximum of the critical value for the pressure and the supremum of Lyapunov dimensions of invariant measures $\mu$ for which $\int\Phi\,d\mu=\alpha$. Our multifractal results are new in both the finitely generated and the infinitely generated setting.
Superconducting high gradient magnetic separator

Results are reported from studies examining the applicability of a superconducting high-gradient magnetic separator to the extraction of uranium from seawater. Factors affecting the efficiency of separation such as shape of the filter cross section, diameter, diameter of separated particles, susceptibility, and external field were examined. In the tests two types of stainless-steel filaments of 30- and 100- mu m diameter were prepared and inserted into a matrix of CuO and Fe/sub 2/O/sub 3/ particles. It was found possible to separate the particles selectively according to susceptibility. >
The $S$-transform in arbitrary dimensions

In this note we report the solution of the problem of defining the $S$-transform in Free Probability Theory in arbitrary dimensions. This is achieved by generalising the theory and embedding it into an algebraic-geometric framework. Finally, we classify the groups arising as distributions of s-tuples of non-commutative random variables.
Covering Array Bounds Using Analytical Techniques

A $t$-covering array with entries from the alphabet ${\cal Q}=\{0,1,\ldots,q-1\}$ is a $k\times n$ stack, so that for any choice of $t$ (typically non-consecutive) columns, each of the $q^{t}$ possible $t$-letter words over ${\cal Q}$ appear at least once among the rows of the selected columns. We will show how a combination of the Lov\'asz local lemma; combinatorial analysis; Stirling's formula; and Calculus enables one to find better asymptotic bounds for the minimum size of $t$-covering arrays, notably for $t = 3, 4$. Here size is measured in the number of rows, as expressed in terms of the number of columns.
Numerical Simulation of the Development of AMEX Tropical Cyclone Irma

Abstract High resolution observational data from the Australian Monsoon Experiment have been used to verify simulations of the development of tropical cyclone Irma. From a small amplitude, prehurricane cloud cluster, the FSU high resolution regional prediction model quite skillfully simulates the temporal and spatial structure changes during development. The results are, however, sensitive to the initial windfield and somewhat sensitive to both the initial moisture field and the imposed boundary conditions. Temporal changes in the symmetric and asymmetric structure of the observed and simulated disturbances are compared. Apart from other well-documented necessary conditions, changes in the storm's vertical structure, and the development of horizontal asymmetries appear to be crucial features of the simulated development. The associated physical processes are discussed. Deficiencies in the simulation are lack of diurnal modulation of the vertical motion field, larger than diagnosed values of vertical motio.