Miracle-dz/UniFAR-FTUs huggingface dataset:
International comparison CCQM-K46: Ammonia in nitrogen

Ammonia is an important compound in the chemical industry. It is widely used and is the basis for producing other compounds containing nitrogen. Ammonia is also very hazardous, and consequently emissions of ammonia need be controlled and monitored. In the past years, several national metrology institutes have developed facilities for the preparation of Primary Standard gas Mixtures (PSMs), dynamically generated ammonia mixtures and facilities for comparing and certifying gas mixtures containing ammonia. The amount-of-substance fraction level of ammonia chosen for this key comparison is 30–50 µmol/mol. The results of this key comparison revealed that there is at present no consensus among static and dynamic techniques for gas mixture preparation for this component in this range. As key comparison reference value (KCRV), the mean of the three methods is used. In its uncertainty, no allowance is made for the observed biases. With respect to the KCRV, only two laboratories report consistent results. When grouped in accordance with the employed methods, the results are consistent. Further experimental work is needed. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm. org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).
Atomistic simulations on the thermal stability of the antisite pair in 3C- and 4H-SiC

The thermal stability of the first-neighbor antisite pair configurations in 3C- and 4H-SiC is investigated by a comprehensive atomistic study. At first the structure and energetics of these defects is determined in order to check the accuracy of the Gao-Weber interatomic potential used. The results are comparable with literature data obtained by the density-functional theory. Then, the lifetime of the antisite pair configurations is calculated for temperatures between 800 and 2500 K. Both in 3C- and 4H-SiC the thermal stability of the antisite pairs is rather low. In contrast to previous theoretical interpretations, the antisite pair can be therefore not correlated with the DI photoluminescence center that is stable to above 2000 K. The atomic mechanisms during the recombination of the antisite pair in 3C-SiC and of three antisite pair configurations in 4H-SiC is a modified concerted exchange. Due to the different sizes of the silicon and the carbon atoms, this process is not identical with the concerted exchange in Si. Two intermediate metastable configurations found during the recombination are similar to the bond defect in Si. Since the SiC lattice contains two types of atoms, there are also two different types of bond defects. The two bond defects canmore » be considered as the result of the incomplete recombination of a carbon vacancy and a neighboring mixed dumbbell interstitial. For selected temperatures the thermal stability of the antisite pair in 3C-SiC is investigated by molecular dynamics simulations that are based on the density-functional theory. Their results are very similar to those of the atomistic study, i.e. the Gao-Weber potential describes the antisite pair and its recombination reasonably well. The antisite pair in 4H-SiC with the two atoms on hexagonal sites has a slightly different formation energy than the other three antisite pair configurations in 4H-SiC. Its lifetime shows another dependence on the temperature, and its recombination is characterized by a separate motion of atoms. « less
Tunable MoS2 bandgap in MoS2-graphene heterostructures

Using density functional theory calculations with van der Waals corrections, we investigated how the interlayer orientation affects the structure and electronic properties of MoS2-graphene bilayer heterostructures. Changing the orientation of graphene with respect to MoS2 strongly influences the type and the value of the electronic bandgap in MoS2, while not significantly altering the binding energy between the layers or the interlayer spacing. We show that the physical origin of this tunable bandgap arises from variations in the S–S interplanar distance (MoS2 thickness) with the interlayer orientation, variations which are caused by electron transfer away from the Mo–S bonds.
Laboratory observation of the 2nu2 band of the H3(+) molecular ion

Wavenumbers and assignments are reported for lines of the 2nu2 vibrational band of the H3(+) molecular ion, observed in the range 4500-5100/cm as pressure-enhanced emission lines from a hollow-cathode electrical discharge through molecular hydrogen. The assignments are based on ab initio calculations, previously tested for the nu2 fundamental and for difference bands, and here extended up to angular momentum states with J = 12. Calculated Einstein A(if) coefficients of the lines are presented and imply a rotational temperature of about 1800 + or - 200 K in the laboratory spectrum, which is probably due to emission by excited H{sub 3}(+) formed in the exothermic reaction H{sub 2}(+) + H{sub 2}-H{sub 3}(+) + H. The H{sub 3}(+) 2nu2 band has recently been identified in emission from the auroral hot spots of Jupiter, and the present more extensive data will assist in further astronomical searches for this ion. 33 refs.
Visible light emission from semiconducting polymer diodes

We report visible light emission from Shottky diodes made from semiconducting polymers, confirming the discovery by the Cambridge group [Nature 347, 539 (1990)]. Our results demonstrate that light‐emitting diodes can be fabricated by casting the polymer film from solution with no subsequent processing or heat treatment required. Electrical characterization reveals diode behavior with rectification ratios greater than 104. We propose that tunneling of electrons from the recitifying metal contact into the gap states of the positive polaron majority carriers dominates current flow and provides the mechanism for light emission.
The radiation of sound from a finite ring-forced cylindrical elastic shell I. Wiener–Hopf analysis

The radiation of sound from a finite fluid-loaded cylindrical elastic shell is examined by means of the modified Wiener–Hopf technique. The shell is freely submerged in an inviscid compressible stationary fluid of infinite extent and axisymmetrically excited by a ring force. The problem is formulated as a three-part Wiener–Hopf equation with three unknown functions, and is recast as two uncoupled Fredholm integral equations of the second kind by utilizing a factorization and decomposition procedure. When the product of the cylinder length l and the wave number k is large, asymptotic analysis can be applied to the integral equations, which reduces them to a finite system of algebraic equations corresponding to a set of unknown constants, including the edge displacements. The method provides a straightforward formulation for the solution and is valid for arbitrary fluid loading. Numerical results are presented for the radiated far-field velocity potential. This requires a numerical decomposition of the Wiener–Hopf kernel and the solution of the set of simultaneous equations.
Bootstrap Techniques for Signal Processing

2007) it is useful if you are already familiar with programming and evolutionary biology. The level of detail of the functions discussed goes beyond that in the online help files. The detailed explanations are reminiscent of those provided by Venables and Ripley (2001). The organization of functions by similar analytic goal is useful; if you have an idea of what you want to try, consulting this book will suggest alternatives that you may not know about. The introduction to R is brief but appropriate if there are more knowledgeable people around to help with the learning process. Given the plethora of R manuals and books available, this is not a critical flaw and may even be a virtue. The introduction is certainly detailed enough to get one started; however, the jump from the introduction to R to the introduction to methods in R for evolutionary biology is a bit abrupt. My larger concern about this book is that I do not feel that it is appropriate for a statistician interested in but not already well acquainted with evolutionary biology. References are given for each method discussed, but the framing discussion is too brief. I keep a copy of the book by Venables and Ripley (2001) on my desk more for the brief introduction to a variety of applied statistics methods than for their implementations in S. This book will help with the implementations in R of a wide variety of methods for phylogentic inference, but not for introductions on how these methods work. I feel it would be a far stronger book if it could stand better on its own. I can also envision this as an excellent textbook. By either providing the students with the references to the techniques or having the students chase down these references on their own, the aforementioned voids can be circumvented. The start of the class could acquaint the students with any missing background material. Further lectures could provide an excellent opportunity to discuss techniques that the book covers in detail. This book can help organize the ideas, and make it easier for students to implement them on data. This will help make the foreign elements of the class (biology for statisticians, statistics for biologists) more concrete and easier to learn.
Application of vortex identification schemes to direct numerical simulation data of a transitional boundary layer

We have demonstrated how various vortex identification and visualization criteria perform using direct numerical simulation data from a transitional and turbulent boundary layer by Sayadi, Hamman, and Moin [“Direct numerical simulation of complete transition to turbulence via h-type and k-type secondary instabilities,” Technical Report, Stanford University, CTR Annual Research Briefs, 2011]. The presence of well-known Λ vortices in the transitional region provides a well defined and yet realistic benchmark for evaluation of various criteria. We investigate the impact of changing the threshold used for iso-surface plotting.
Monotonicity and the Generalized Inverse

Necessary and sufficient conditions are given in order that a matrix A have a nonnegative generalized inverse $A^ + $. The concept of row-monotonicity is introduced and a characterization of row-monotone matrices is used to derive a necessary and sufficient condition on $A\geqq 0$ so that $A^ + \geqq 0$. Applications of these results include the special case where A has full column rank, thus yielding results of Collatz, Mangasarian and Ben-Israel as corollaries.
An approximation path planning algorithm for fixed-wing UAVs in stationary obstacle environment

In this paper, we study the curvature-constrained path planning problem for fixed-wing UAVs in stationary obstacle environment. We first use enclosing circles to redefine the polygonal obstacles, thus incorporating curvature constraint into the path planning algorithm. It is proved in this paper that the curvature-constrained path planning problem in the presence of stationary circular obstacles is NP-complete. To reduce the computational complexity of the path planning problem, a novel approximation planning scheme based on Dubins path is proposed. In the scheme, incremental planning strategy and orientation angle discretization method are used to compute the flyable Dubins trajectory set between the two given points. Compared with the existing algorithms, the proposed algorithm performs well in numerical experiments and computational cost is relatively low.
Absorption dips and the properties of the accretion stream in polars

Les observations simultanees dans les bandes RX, optiques et IR des creux d'absorption dans le systeme type AM Herculis, EF Eri, sont utilisees pour determiner les proprietes de ces creux et developper un modele simple dans lequel ils sont causes par l'absorption dans le courant d'accretion lorsqu'il traverse la ligne de visee vers la region d'emission RX/optique localisee au voisinage du pole magnetique de la naine blanche
TIME SERIES MODELS OF THREE SETS OF RXTE OBSERVATIONS OF 4U 1543−47

The X-ray nova 4U 1543−47 was in a different physical state (low/hard, high/soft, and very high) during the acquisition of each of the three time series analyzed in this paper. Standard time series models of the autoregressive moving average (ARMA) family are fitted to these series. The low/hard data can be adequately modeled by a simple low-order model with fixed coefficients, once the slowly varying mean count rate has been accounted for. The high/soft series requires a higher order model, or an ARMA model with variable coefficients. The very high state is characterized by a succession of “dips,” with roughly equal depths. These seem to appear independently of one another. The underlying stochastic series can again be modeled by an ARMA form, or roughly as the sum of an ARMA series and white noise. The structuring of each model in terms of short-lived aperiodic and “quasi-periodic” components is discussed.
A new level set model for cell image segmentation

In this paper we first determine three phases of cell images: background, cytoplasm and nucleolus according to the general physical characteristics of cell images, and then develop a variational model, based on these characteristics, to segment nucleolus and cytoplasm from their relatively complicated backgrounds. In the meantime, the preprocessing obtained information of cell images using the OTSU algorithm is used to initialize the level set function in the model, which can speed up the segmentation and present satisfactory results in cell image processing.
Dispersion-relation-preserving finite difference schemes for computational acoustics

Acoustics problems are governed by the linearized Euler equations. According to wave propagation theory, the number of wave modes and their wave propagation characteristics are all encoded in the dispersion relations of the governing equations. Thus one is assured that the numerical solutions of a high order finite difference scheme will have the same number of wave modes (namely, the acoustic, vorticity, and entropy waves), the same wave propagation characteristics (namely, nondispersive, nondissipative, and isotropic) and the same wave speeds as those of the solutions of the Euler equations if both systems of equations have the same dispersion relations. Finite difference schemes which have the same dispersion relations as the original partial differential equations are referred to as dispersion-relation-preserving (DRP) schemes. A way to construct time marching DRP schemes by optimizing the finite difference approximations of the space and time derivatives in the wave number and frequency space is proposed. The stability of these schemes is analyzed and a sufficient condition for numerical stability is established. A set of radiation and outflow boundary conditions compatible with the DRP schemes is constructed. These conditions are derived from the asymptotic solutions of the governing equations. The asymptotic solutions are found by the use of Fourier-Laplace transforms and the method of stationary phase. A sequence of numerical simulations has been carried out. These simulations are designed to test the effectiveness of the DRP schemes and the radiation and outflow boundary conditions. The computed solutions agree very favorably with the exact solutions. The radiation boundary conditions perform satisfactorily causing little acoustic reflections. The outflow boundary conditions are found to be quite transparent to outgoing disturbances even when the disturbances are made up of a combination of acoustic, vorticity, and entropy waves.
An alternate derivation of the three-dimensional Hilbert transform relations from first principles

Several techniques for determining the location, geometry, and strength of a source are based on a knowledge of the magnetic gradients generated by that source. Hood (1965), Bhattacharyya (1966), and Rao et al. (1981) detailed three of these gradient methods. For many years, geophysicists have used the two‐dimensional (2-D) Hilbert transform to approximate the vertical gradient from measurements of the horizontal gradient in the magnetic‐field intensity (Nabighian, 1972; Stanley and Green, 1976; Stanley, 1977; Mohan et al., 1982). This technique is of limited applicability because of the implicit assumption that the source is a linear, 2-D body oriented at right angles to the profile direction.
Using Spherical–Radial Quadrature to Fit Generalized Linear Mixed Effects Models

Although generalized linear mixed effects models have received much attention in the statistical literature, there is still no computationally efficient algorithm for computing maximum likelihood estimates for such models when there are a moderate number of random effects. Existing algorithms are either computationally intensive or they compute estimates from an approximate likelihood. Here we propose an algorithm—the spherical–radial algorithm—that is computationally efficient and computes maximum likelihood estimates. Although we concentrate on two-level, generalized linear mixed effects models, the same algorithm can be applied to many other models as well, including nonlinear mixed effects models and frailty models. The computational difficulty for estimation in these models is in integrating the joint distribution of the data and the random effects to obtain the marginal distribution of the data. Our algorithm uses a multidimensional quadrature rule developed in earlier literature to integrate the joint density. This article discusses how this rule may be combined with an optimization algorithm to efficiently compute maximum likelihood estimates. Because of stratification and other aspects of the quadrature rule, the resulting integral estimator has significantly less variance than can be obtained through simple Monte Carlo integration. Computational efficiency is achieved, in part, because relatively few evaluations of the joint density may be required in the numerical integration.
Valence Electron Spectra of Benzene and the Hexafluorides of Sulphur, Molybdenum, Tungsten and Uranium. An Application of Multichannel Detector Technique to UV-Valence Electron Spectroscopy

HeI induced valence electron spectra of benzene and the hexafluorides of sulphur, molybdenum, tungsten and uranium are presented together with a HeII spectrum of sulphur hexafluoride. Vibrational band structure has been resolved in the spectra of all molecules and the energies of these bands are reported. A description is also given of the multichannel detector system which has facilitated the recordings of these spectra.
Correlating local structure with inhomogeneous elastic deformation in a metallic glass

The elastic response of metallic glasses (MGs) is inhomogeneous, due to the wide variation of local structural arrangements. Here, we present molecular dynamics simulations on a one-million-atoms sample of a Cu64Zr36 model MG, correlating the atomic strain and non-affine displacement with short-range order. Cu atoms in full icosahedra experience less atomic relaxation and behave stiffer, while the rest of Cu atoms contribute more to anelasticity on the timescale of simulation.
Sphere Image Representation of Triangular Mesh and its Application

Image processing algorithms are based on the idea that all pixels of it ranked over the orderly rows, which make the algorithms easier to be implemented. Extending image processing algorithms to triangular mesh is always an important idea for triangular mesh processing. But since the topology of a triangular mesh is not as simple as an image, triangular mesh processing is relatively difficult. This paper presented a new sphere image representation of a triangular mesh, which is an image as well as a graphic, and based on it, image processing algorithms can be easily extended to a triangular mesh. Experimental results show that by simply extending the image processing algorithms the presented sphere image representation can effectively reduce difficult of segmentation and mesh editing. Moreover the sphere image representation can be used for more triangular mesh processing applications.
Multiresolution regularized least squares image reconstruction based on wavelet in optical tomography

In this paper, we present a wavelet based multigrid approach to solve the perturbation equation encountered in optical tomogrpahy. With this scheme, the unkown image, the data, as well as weight matrix are all represented by wavelet expansions, and thus yielding a multiresolution representation of the original perturbation equation in the wavelet domain. This transformed equation is then solved using multigrid scheme, by which an increasing portion of wavelet coefficients of the unknown image are solved in successive approximations. One can also quickly identify regions of interest from a coarse level reconstruction and restrict the reconstruction in the following fine resolutions to those regions. At each resolution level, a regularized least squares solution is obtained using a conjugate gradient descent method. Compared to a previously reported one grid algorithm, the multigrid method requires substantially shorter computation time under the same reconstruction quality criterion.
Effect of structural variation on the photonic band gap in woodpile photonic crystal with body-centered-cubic symmetry

A woodpile photonic crystal template with body-centered-cubic symmetry can be fabricated by exposing the photoresist to a four-beam interference pattern or a pattern generated through a diffractive optical element. We present detailed photonic band-gap calculations for photonic structures obtained under various possible fabrication conditions. The woodpile photonic crystal has a full photonic band gap up to 19% of the gap center frequency when the photoresist template is converted into silicon. The tolerance of the band gap to deviations of the structural parameters from their optimum values indicates great flexibility of the holographic fabrication process.
Classical and quantum oscillator model of an atom in a classical field with time-dependent damping

A quantum system with time dependent damping, which is canonically transformed from a conservative system, is dealt with. From the wave functions of the conservative system, we use a perturbative method to find the wave function of the damped quantum system under the influence of an external field. We consider the atomic optical susceptibility of the classical oscillator model with a damping function. With the wave function of the damped quantum system under the influence of the external field, we obtain the atomic optical susceptibility of the system. In both the quantum and the classical treatments, we show that the susceptibility depends on a frequency that is not the frequency of the applied field.