Miracle-dz/UniFAR-FTUs huggingface dataset:
CO Survey of Nearby Spiral Galaxies with the Nobeyama 45-m Telescope: II. Distribution and Dynamics of Molecular Gas

We have studied the distribution and dynamics of molecular gas in galaxies by observing CO emission mainly along the major and minor axes of 28 nearby spiral galaxies with the 45-m telescope of the Nobeyama Radio Observatory. The observations showed that the surface density of molecular gas indicates an exponential distribution in the region of theflat (differential) rotation curve for all spiral galaxies. This could be becausethe radial distribution is determined by gas inflow due to the viscosity of molecular clouds. The surface density of molecular gas in barred galaxies also shows a characteristic distribution in the region of the bar, suggesting gas inflow along the bar by the bar potential and perpendicular to the bar by viscosity. Such a transfer of molecular gas increases the gas density in the central region, probably causing the evolution of the rotation curve, which is determined by the mass distribution, on the time scale of the galaxy age. We compared the radial distribution of the surface density of H I with that of H2, and found same scale length of the exponential distribution in the Virgo galaxies and a much larger scale length in field galaxies for H I. This could be due to a difference in the viscosity coefficient of the H I gas.
Optimal Control for Partially Observed Diffusions

Stochastic control problems are considered in which a state process $X_t$ and an observation process $Y_t$ are governed by Ito-sense stochastic differential equations driven by independent Brownian motions. The control $U_t$ enters linearly in the dynamics of $X_t$. A “separated”control problem is introduced, in which the state at any time t is a measure $\Lambda_t$ representing an unnormalized conditional distribution for $X_t$ given $Y_s$, $U_s$ for $s \leqq t$. The method depends on introducing a pathwise version of $\Lambda_t$ which depends continuously on observation and control trajectories Y, U. Existence of an optimal control is obtained in a suitable class, larger than the usual class of controls admissible in the strict sense that $U_t$ is measurable on the $\sigma $-algebra $\mathcal{F}_t (Y)$ generated by observations $Y_s$, $s \leqq t$. The dynamics of $\Lambda_t$ are studied using a method of forward and backward partial differential equations. Under a suitable nondegeneracy condition, the m.
On the use of the logistic equation in models of food chains

In food chain models the lowest trophic level is often assumed to grow logistically. Anomalous behaviour of the solution of the logistic equation and problems with the introduction of mortality have recently been reported. As predation on the lowest trophic level is a kind of mortality, one expects problems with these food chain models. In this paper we compare two formulations for the lowest trophic level: the logistic growth formulation and the mass balance formulation with resources modelled explicitly. We examine the effects of both models on the dynamic behaviour of a tri-trophic microbial food chain in a chemostat. For this purpose bifurcation diagrams, which give the existence and stability of the equilibria of the nonlinear dynamic system, are used. It turns out that the dynamic behaviours differ in a rather large region of the control parameter space spanned by the dilution rate and the concentration of the resources in the reservoir. We urge that mass balance equations should be used in modelling food chains in chemostats as well as in ecosystems.
Global existence of weak solution to Navier–Stokes equations with large external force and general pressure

We study the 3‐D compressible Navier–Stokes equations with an external potential force and a general pressure. We prove the global‐in‐time existence of weak solutions with small‐energy initial data and with densities being positive and essentially bounded. No smallness assumption is made on the external force. Copyright © 2013 John Wiley & Sons, Ltd.
Entrainment Velocity in an Axisymmetric Turbulent Jet

Mean radial and turbulent radial velocity profiles were measured in a circular jet at up to 40 jet diameters downstream of the jet exit using an LDA. The mean radial velocity in the ambient reservoir (the entrainment velocity) is found to be inversely proportional to the radial distance from the jet centerline. The coefficient of proportionality, c, increases in the zone of flow establishment and reaches a constant after the transition zone. It is suggested that the traditional definition of entrainment velocity, which maintains direct proportionality to the local jet velocity by the entrainment coefficient, should be augmented by this inverse function
Testing for order‐restricted hypotheses in longitudinal data

Summary. In many biomedical studies, we are interested in comparing treatment effects with an inherent ordering. We propose a quadratic score test (QST) based on a quadratic inference function for detecting an order in treatment effects for correlated data. The quadratic inference function is similar to the negative of a log‐likelihood, and it provides test statistics in the spirit of a χ2‐test for testing nested hypotheses as well as for assessing the goodness of fit of model assumptions. Under the null hypothesis of no order restriction, it is shown that the QST statistic has a Wald‐type asymptotic representation and that the asymptotic distribution of the QST statistic is a weighted χ2‐distribution. Furthermore, an asymptotic distribution of the QST statistic under an arbitrary convex cone alternative is provided. The performance of the QST is investigated through Monte Carlo simulation experiments. Analysis of the polyposis data demonstrates that the QST outperforms the Wald test when data are highly correlated with a small sample size and there is a significant amount of missing data with a small number of clusters. The proposed test statistic accommodates both time‐dependent and time‐independent covariates in a model.
NUMERICAL INVESTIGATION OF FLOW FIELD AND HEAT TRANSFER IN CROSS-CORRUGATED DUCTS

Regenerative and recuperative plate heat exchangers consist of ten of stacked corrugated plates. The orientation of the corrugation between neighboring plates is nonaligned. Multitude contact points between the plates lead to high compressive strength of the heat exchangers. The corrugations give structural stability even at low material thickness of the plates and produce highly complex flow structure which determines the thermal performance and the flow loss of the heat exchanger. Here, flow field and heat transfer in sine-wave crossed-corrugated ducts have been investigated by numerical solution of the Navier-Stokes and energy equations in the laminar and transitional flow regime between Re = 170 and 2000. The ratio of the corrugation wave length {lambda}{sup *} to amplitude a{sup *} has been varied between 7 and 10. The angle of the corrugation of the neighboring plates has been kept fixed at 45 deg. Results show that the critical Reynolds number for self-sustained flow oscillations is about 240. For Reynolds numbers larger than 1000, the Nusselt number and the friction factor are nearly independent of the dimensionless wavelength. Computational results compare well with available experimental results.
TEMPERATURE FIELD WITH THERMAL CYLINDERS IN BUOYANT FLOW IN STABLY STRATIFIED AIR

ABSTRACT The aim of this work is to clarify characteristics of time-dependent temperature behavior in a buoyant flow in stably stratified air in an enclosure. For this aim, the two-dimensional, laminar, time-dependent continuity equation, Navier-Stokes equations with the buoyancy term, and energy equation are solved numerically by finite-difference methods. The computed results at unstratified condition agree well with the previous results, and validate the numerical accuracy. The present computational methods and procedures are therefore valid, and have sufficient grid resolution. As a result, at an adiabatic ceiling of the enclosure or in stably stratified air in the enclosure, a thermal cylinder with high temperature is discovered to occur intermittently near the plume front, and moves upward. However, a thermal cylinder never occurs at unstratified condition. Furthermore, a thermal cylinder exists in both the instantaneous crossover (COI) region at adiabatic condition and the time-averaged crossover (COM) region at stratified condition. In other words, when a thermal cylinder exists, the region with a thermal cylinder is certainly either COM or COI.
Infrared observations of the galactic center. I - Nature of the compact sources

Photometry from 1.25 to 12 . mu.m and spectrophotometry from 8 to 13 . mu.m of the compact sources found in the galactic-center region are reported. In addition, revised 10- and new 20-. mu.m maps with 2.3'' reolution are given. The nature of the compact sources is discussed. Some are best identified as stars or star clusters; the brightest source at 2 . mu.m is probably a supergiant, and the infrared source near the nonthermal radio source is probably a stellar cluster with density greater than 10/sup 6/ M sub solar pc/sup -3/. Other sources emit most of their luminosity at wavelengths of 10 . mu.m and greater; this emission is probably from heated dust. One of the sources is observationally similar to extremely red OH/infrared stars. Other sources have luminosities and linear sizes similar to those of compact H II regions; emission from optically thin silicate dust is seen in these. 7 figures, 1 table.
Aeroelastic Responses of Elastically Suspended Airfoil Systems in Transonic Buffeting Flows

Navier–Stokes simulations are performed to determine the responses of a single-degree-of-freedom pitch airfoil system, as well as those of a two-degree-of-freedom pitch-and-heave system, in buffeting flows. The buffeting flow exhibits shock-wave oscillations of a unique frequency that occurs for some combinations of mean flow angle of attack and transonic Mach numbers. It was found that frequency lock-in may occur, when the frequency of the elastic system is close to the buffet frequency, and the amplitude of the elastic oscillation is above some threshold. Following frequency lock-in, the system response rapidly increases until reaching a limit-cycle oscillation. Synchronization of the transonic aerodynamic buffet phenomenon and the structural elastic modes provides a physical mechanism that leads to a limit-cycle oscillation, as observed in the current computational study.
Influence of Inflow Disturbances on Stagnation-Region Heat Transfer

Numerical simulations of laminar stagnation-region heat transfer in the presence of freestream disturbances are performed. The sensitivity of heat transfer in stagnation-region to freestream vorticity is scrutinized by varying the length scale, amplitude, and Reynolds number. As an organized inflow disturbance, a spanwise sinusoidal variation is superimposed on the velocity component normal to the wall. An accurate numerical scheme is employed to integrate the compressible Navier-Stokes equations and energy equation. The main emphasis is placed on the length scale of laminar inflow disturbances, which maximizes the heat transfer enhancement. Computational results are presented to disclose the detailed behavior of streamwise vortices. Three regimes of the behavior are found depending on the length scale: these are the damping, attached amplifying, and detached amplifying regimes, respectively. The simulation data are analyzed with an experimental correlation
Vibration sensitivity of a Y-cut quartz thickness-shear resonator

Incremental thickness-shear (TSh) vibrations of a Y-cut quartz crystal plate under time-harmonic biasing extensional deformations are studied using the two-dimensional equations for small fields superposed on finite biasing fields in an electroelastic plate. The incremental TSh vibrations are governed by the well known Mathieu's equation with a time-dependent coefficient. Both free and electrically forced vibrations are studied when the frequency of the biasing deformation is much lower than that of the incremental TSh vibration. Numerical results show that the incremental TSh free vibration mode is both frequency and amplitude modulated. The forced vibration solutions show that both the static and motional capacitances become time-dependent due to the time-harmonic biasing deformation.
Direct Methods for Sparse Matrices

The subject of sparse matrices has its roots in such diverse fields as management science, power systems analysis, surveying, circuit theory, and structural analysis. Mathematical models in all these areas give rise to very large systems of linear equations which could not be solved were it not for the fact that the matrices contain relatively few non-zero entries. Only comparatively recently, in the last fifteen years or so, has it become apparent that the equations can be solved even when the pattern is irregular, and it is primarily the solution of such problems that is considered in this book. The subject is intensely practical and this book is written with practicalities ever in mind. Whenever two methods are applicable, their rival merits are considered, and conclusions are based on practical experience where theoretical comparison is not possible. Non-numeric computing techniques have been included, as well as frequent illustrations, in an attempt to bridge the usually wide gap between the printed page and the working computer code. Despite this practical bias, it is recognized that many aspects of the subject are of interest in their own right, and the book aims to be suitable also for a student course, probably at MSc level. Exercises have been included to illustrate and strengthen understanding of the material, as well as to extend it. Efficient use of sparsity is a key to solving large problems in many fields. This book will supply both insight and answers for those attempting to solve these problems.
Local analytic integrability for nilpotent centers

Let X(x,y) and Y(x,y) be real analytic functions without constant and linear terms defined in a neighborhood of the origin. Assume that the analytic differential system \dot{x}=y+ X(x,y), \dot{y}=Y(x,y) has a nilpotent center at the origin. The first integrals, formal or analytic, will be real except if we say explicitly the converse. We prove the following. If X= y f(x,y^2) and Y= g(x,y^2), then the systemhas a local analytic first integral of the form H=y^2+F(x,y),where F starts with terms of order higher than two. If the system has a formal first integral, then it hasa formal first integral of the form H=y^2+F(x,y), where Fstarts with terms of order higher than two. In particular, if thesystem has a local analytic first integral defined at the origin,then it has a local analytic first integral of the formH=y^2+F(x,y), where F starts with terms of order higher than two. As an application we characterize the nilpotent centersfor the differential systems \dot{x}=y+P_3(x,y),\dot{y}=Q_3(x,y), which have a local analytic first integral,where P_3 and Q_3 are homogeneous polynomials of degree three.
Spatial-temporal characteristics of flickering aurora as seen by high-speed EMCCD imaging observations

[1] We conducted high-speed imaging observations of flickering aurora at 100 Hz sampling rate using electron multiplying charge-coupled device in Alaska during 2009–2010 winter season. We detected various types of flickering aurora, including drifting and rotating features at a frequency below 15 Hz. We identified, for the first time, flickering stripes and some other unusual flickering events at frequency of higher than 20 Hz on the imaging observations. A dispersion relation derived from a statistical analysis of observed images is compared with the theoretical dispersion curve of O+ electromagnetic ion cyclotron (EMIC) waves. The frequencies and spatial scales calculated from a coherence/phase analysis based on an interference theory are consistent with the wave dispersion relation derived from the statistical analysis, suggesting that the obtained results are essentially consistent with the scenario that the interference of EMIC waves produces the observed dispersion relation of flickering aurora. Furthermore, flickering frequencies higher than 20 Hz are confirmed from our observations, which are higher than expected frequency of O+ EMIC waves at altitudes of several thousand kilometers. We therefore suggest that high-frequency waves such as He+ and H+ EMIC waves may also contribute to produce a significant fraction of flickering aurora.
Multidimensional de-aliased Cadzow reconstruction of seismic records

ABSTRACTWe tested a strategy for beyond-alias interpolation of seismic data using Cadzow reconstruction. The strategy enables Cadzow reconstruction to be used for interpolation of regularly sampled seismic records. First, in the frequency-space (f-x) domain, we generated a Hankel matrix from the spatial samples of the low frequencies. To perform interpolation at a given frequency, the spatial samples were interlaced with zero samples and another Hankel matrix was generated from the zero-interlaced data. Next, the rank-reduced eigen-decomposition of the Hankel matrix at low frequencies was used for beyond-alias preconditioning of the Hankel matrix at a given frequency. Finally, antidiagonal averaging of the conditioned Hankel matrix produced the final interpolated data. In addition, the multidimensional extension of the proposed algorithm was explained. The proposed method provides a unifying thread between reduced-rank Cadzow reconstruction and beyond alias f-x prediction error interpolation. Synthetic an.
New Investigations of the A2Δ-X2Π Band System in the CH Radical and a New Reduction of the Vibration-Rotation Spectrum of CH from the ATMOS Spectra

Abstract Seven bands of the A 2 Δ- X 2 Π system of the CH radical have been photographed in emission from a Geissler tube using conventional spectroscopic techniques. Under high resolution and using Th lines as standards, as well as an interferometric comparator equipped with a photoelectric scanning device, the 0-0, 1-1, 2-2, 0-1, and 1-2 bands have been rephotographed and the 3-3 and 2-3 bands, with a total number of 144 lines, have been recorded for the first time. In the previously reported ( J. Mol. Spectrosc. 134, 305, 1989; 147, 16, 1991) evaluation of the ATMOS spectrum of CH for determining the molecular parameters we found total interparameter correlations between some of them, due to the absence of high- J lines of the P and Q branches. With the help of the precise constants obtained from our 0-0 band measurements (12 branches with J max = 24.5, f = 181, σ = 0.0025 cm −1 ) of the A 2 Δ- X 2 Π transition, we have been able to remove the correlations and obtain more accurate molecular parameters for the X 2 Π ground state. These constants have subsequently been used to derive new exact molecular parameters for the A 2 Δ , ν = 1, 2, and 3 levels of CH. The Λ-doubling constants in the A 2 Δ state were obtained for the first time. The complex vibrational analysis has been carried out to determine the equilibrium molecular constants. Also, RKR potentials and r -centroids have been calculated for both the combining states, as well as Franck-Condon factors for the A - X system.
Cloud-Resolving Satellite Data Assimilation: Information Content of IR Window Observations and Uncertainties in Estimation

Abstract This study addresses the problem of four-dimensional (4D) estimation of a cloudy atmosphere on cloud-resolving scales using satellite remote sensing measurements. The motivation is to develop a methodology for accurate estimation of cloud properties and the associated atmospheric environment on small spatial scales but over large regions to aid in better understanding of the clouds and their role in the atmospheric system. The problem is initially approached by the study of the assimilation of the Geostationary Operational Environmental Satellite (GOES) imager observations into a cloud-resolving model with explicit bulk cloud microphysical parameterization. A new 4D variational data assimilation (4DVAR) research system with the cloud-resolving capability is applied to a case of a multilayered cloud evolution without convection. In the experiments the information content of the IR window channels is addressed as well as the sensitivity of estimation to lateral boundary condition errors, model firs.
Laboratory and Theoretical Simulation of 3.4 μm Spectra of Hydrocarbons in Interstellar Sources

The presence of hydrocarbons in interstellar clouds and in some emission objects can be inferred from the appearance of spectral features near 3.4 μm that are characteristic of CH2 and CH3 groups. While the 3.4 μm band attributable to these hydrocarbons has been found to be similar in sources such as GC IRS 6E and CRL 618 (Chiar et al. 1998), there are significant variations in the relative amplitude of individual components in other sources such as NGC 7538 IRS9 (Allamandola et al. 1992). This indicates that the composition of these hydrocarbons may depend on ambient conditions in interstellar clouds. To investigate this possibility, we have analyzed observational IR spectra of GC IRS 6E, CRL 618, IRAS 05341+0852, and NGC 7538 IRS9 to extract spectral bands associated with CH2 and CH3 groups in each of these sources. These components are compared with the features that appear in laboratory absorption and emission spectra of hydrogenated amorphous carbon. It is found that significant differences exist in the CH2/CH3 ratio in individual sources. In particular, we find that CH3 groups are suppressed in dense cloud dust but that CH2 groups are still abundant. The properties of individual spectral components within the 3.4 μm interstellar band are discussed and compared to laboratory and theoretical data on IR spectra of certain hydrocarbon molecules, as well as that of hydrogenated amorphous carbon. Simulation of 3.4 μm spectra using a random covalent network model is shown to provide a useful way to extract structural and bonding information for specific chemical groups in interstellar material.
High-latitude day side electric field and particle measurements

Two rockets carrying electric field and low-energy particle instrumentation were launched near noon at 80 deg magnetic latitude. One flight encountered polar cap conditions only, whereas the other traversed part of the polar cusp. Although weak particle precipitation was measured on both flights, bursts of intense magnetosheath-type electron fluxes were detected on the latter. Strong electric fields such as would result from antisunward convection were observed during both flights. The measurements are compared with results obtained by other types of spacecraft and are interpreted in the light of those data. It is concluded that direct access of magnetosheath electrons is very variable and occurs in small regions within a larger overall region. -
Explicit construction of universal operator algebras and applications to polynomial factorization

Using the characterization of unital operator algebras developed in [6], we give explicit internal definitions of the free product and the maximal operator-algebra tensor product of operator algebras and of the group operator algebra OA(G) of a discrete semigroup G (if G is a discrete group, then OA(G) coincides with the group C*-algebra C*(G)). This approach leads to new factorization theorems for polynomials in one and two variables.