Miracle-dz/UniFAR-FTUs huggingface dataset:
A Finite-Amplitude Eliassen-Palm Theorem in Isentropic Coordinates

Abstract Isentropic coordinates are used to generalize to finite amplitude the celebrated theorem (1.1) of Eliassen and Palm(1961),under non-acceleration conditions. This primitive-equation result also generalizes the finite-amplitude quasi-geostrophic result of Edmon et at. (1980). A simple physical interpretation is provided, and a set of transformed Eulerian-mean equations arises naturally in the course of the analysis. Isentropes which intersect the lower boundary need special attention; the technique developed to handle them is a generalization of an idea due to Lorenz (1955), and may be of use in other contexts. Mention is also made of a version of the theorem valid for small-amplitude, transient, non-conservative disturbances.
Failure of the Chapman‐Jouguet Theory for Liquid and Solid Explosives

The usual treatment of unsupported detonation, often called the Chapman‐Jouguet theory, is based on four assumptions: (1) the detonation approaches a steady state, (2) the flow is laminar and one‐dimensional, (3) the detonation products approach a state of chemical equilibrium some distance behind the detonation front, and (4) the detonation velocity is the minimum permitted by the conservation conditions. Wood and Fickett proposed experiments to test the validity of the Chapman‐Jouguet ``theory,'' not requiring knowledge or assumptions about the nature of the equation of state of the detonation products, by making variations of the initial state of the explosive. The results of experiments are reported in which the initial state was varied (1) by using mixtures of nitromethane and another liquid which has the same atomic composition as nitromethane, and (2) by using TNT as liquid and as solid. These results show that the Chapman‐Jouguet theory is violated. The calculated pressures are 15 to 20% below the.
Stability analysis of Euler‐Bernoulli beam with input delay in the boundary control

In this paper, we investigate an Euler‐Bernoulli system with input delay in the boundary control. Suppose that there is no delay in observation, y(t), of the system, and a partial input delay in the boundary control. The collocated boundary feedback control law u(t) = αy(t) + βy(t − τ) is applied to obtain the closed loop system. By spectral analysis and Lyapunov method, we show that: when α>|β|, the closed loop system is exponentially stable for any τ>0; when α<|β|, the system is unstable for any τ>0; when α = |β|, the system is asymptotically stable for almost all τ>0. Finally, we provide numerical simulations to show the spectral distribution for different values of α and β.
Normal modes at small cubes and rectangular particles

The normal electromagnetic modes at small cubes and rectangular parallelepipeds are discussed. An expansion in terms of external multipoles is used; this allows an analytical evaluation of all elements of the interaction matrix. A cluster point of eigenvalues arises at the eigenvalue epsilon int( omega )+ epsilon ext( omega )=0 of a half-space. Only a few terms are needed to obtain convergence of the isolated eigenvalues which give rise to optical absorption peaks. The maximum dipole absorption peak moves from the bulk eigenvalue epsilon int( omega )=0 to the monopole eigenvalue epsilon int( omega )=- infinity with increasing extension of the parallelepiped in the direction of the dipole.
Scaling down the plant condition number scales up the size of uncertainty

It is shown for a special case that design limitations due to an ill-conditioned plant are invariant under scaling even though the size of the condition number is not. The argument is as follows. The standard design problem utilized to study ill-conditioned plants is a robust performance problem. One cannot study robust performance without descriptions of the modeling uncertainty and of the performance goals. These descriptions must necessarily be stated in the same set of units as those used to describe the plant. Changing the plant description by changing units also changes the description of the uncertainty and performance goals. A careful analysis reveals that the robustness difficulty therefore remains the same. <<ETX>>
Chaos: An Introduction to Dynamical Systems

One-Dimensional Maps. - Two-Dimensional Maps. - Chaos. - Fractals. - Chaos in Two-Dimensional Maps. - Chaotic Attractors. - Differential Equations. - Periodic Orbits and Limit Sets. - Chaos in Differential Equations. - Stable Manifolds and Crises. - Bifurcations. - Cascades. - State Reconstruction from Data.
Small-scale structure of interstellar H I clouds

The VLA has been used to synthesize the spatial distribution of 21-cm wavelength H I absorption from some 15 galactic clouds occulting 3C 111, 3C 161, and 3C 348. The angular resolution of the observations is between 3.5 and 4.4 arcsec, and the background continua extend irregularly over regions of angular size 1 to 3 arcmin. On scales of 1 arcmin, it is found that substantial but smooth variations in channel and line properties are the norm, rather than the exception. The observations suggest that the internal structure of H I (or diffuse) clouds is ordered, in the sense that any underlying chaotic behavior occurs on scales much smaller than the resolution, but still highly nonuniform. 27 references
Asymptotically efficient self-tuning regulators

This paper studies the problem of adaptive regulation of linear systems with white-noise disturbances. The apparent dilemma between the control objective and the need of information for parameter estimation is resolved by occasional use of white-noise probing inputs and by a reparametrization of the model. Insights into the question concerning how often and when such probing inputs should be introduced are provided by the concept of “asymptotic efficiency,” which quantifies the asymptotically minimal cost due to parameter ignorance, or equivalently, due to the infeasibility of using the optimal regulator that assumes knowledge of the system parameters. Asymptotically efficient adaptive regulators are constructed by making use of certain basic properties of adaptive predictors involving recursive least squares for the reparametrized model.
Plasma dynamics of an arc‐driven, electromagnetic, projectile accelerator

A model is analyzed to study the electromagnetic acceleration of projectiles using a device known as the rail gun. Current is conducted between the rails by a plasma arc which drives the projectile. The analysis includes determining the electromagnetic fields within the gun and solving the fluid‐mechanical equations of the plasma under the assumption that the flow parameters are steady in a frame that accelerates with the arc. Specifically, a set of coupled equations is derived which, when solved, yields the properties of the arc and the acceleration of the projectile. A limiting‐case analytic solution to the equations is found, and an iterative technique is employed to solve the equations numerically in the more general case. The results of the calculation are applied to analyze the arc in an experiment recently carried out by Rashleigh and Marshall. Some approximate scaling relations, which indicate how the properties of the arc vary with the dimensions of the rail gun, the mass of the projectile, the m.
Direct and large-eddy simulations of three-dimensional compressible Navier-Stokes turbulence

This paper reports results from the numerical implementation and testing of the compressible large‐eddy simulation (LES) model described by Speziale et al. [Phys. Fluids 31, 940 (1988)] and Erlebacher et al. (to appear in J. Fluid Mech.). Relevant quantities from 323 ‘‘coarse grid’’ LES solutions are compared with results generated from 963 direct numerical simulations (DNS) of three‐dimensional compressible turbulence. It is found that the 323 LES results overall agree well with their 963 DNS counterparts. Moreover, the new DNS results confirm several recent conclusions about compressible turbulence that have been based primarily on two‐dimensional simulations.
Eight more ultra luminous X-ray candidates unmasked

Aims. We aim to identify the nature of several objects previously catalogued as ultra-luminous X-ray (ULX) source candidates. Methods. Long-slit spectroscopy of the optical counterparts has been carried out. Results. The eight objects are at higher redshift than their putative parent galaxies. Conclusions. It is found that these eight previously catalogued ULX candidates, most of them projected in galactic halos are actually background unrelated objects. This result confirms the high degree of contamination present in current catalogues of ULXs.
Ionization of Atomic Oxygen on Electron Impact

The cross section for ionization of atomic oxygen was measured by using modulated atomic beam techniques. First the ratio of the cross sections for production of the molecular oxygen ion and for total ion production in collisions of electrons with oxygen molecules was measured. Then the ratio of the ionization cross section of the free oxygen atom and the cross section for production of the molecular ion in electron-molecule collisions was determined. From the previously known total ioni zation cross section of the molecule, and the measured ratios, the unknown cross sections were determined. The experimental results are compared with the calculations of Seaton. (auth)
Non-mesonic weak decay of hypernuclei with effective field theory

The ΛN → NN interaction, the main responsible for the decay of heavy hypernuclei, is described within the effective field theory (EFT) framework. The EFT is developed up to (q⃗2), where q⃗ is the transferred momentum between the interacting baryons. Numerical values for the leading order low-energy constants are obtained by two means. First, from a fit to the hypernuclear decay observables, and second, by comparing the EFT to the one-meson-exchange model describing the same interaction. All the two-pion exchange diagrams entering at the next-to-leading in the EFT have been calculated.
A fast computation of the secondary ion production in the ionosphere of Mars

We present an analytic method for the rapid computation of secondary ion and electron production due to electron impact as suprathermal electrons produced by primary photoproduction propagate through the neutral background Martian atmosphere. We use a one-dimensional kinetic model, Trans-Mars, that solves a stationary Boltzmann transport equation to describe the ionosphere of Mars with the neutral background atmosphere (temperatures, number densities and geopotential heights) provided by a three-dimensional global circulation model, MarTIM. Parameters are given to allow the rapid computation of secondary ion production for 11 ion species (CO+(2), CO++(2), CO+, C+, N+(2), N++(2), N+, O+(2), O++(2), O+, O++) as well as for the secondary electron production. We use the neutral global circulation model to show that while the efficiency (epsilon) of ion and electron production (ratio of secondary to primary production) does vary with solar zenith angle it can be parametrized with a simple function, which is given. We also show that variations with solar cycle and solar longitude are negligible about the region of the primary and secondary production peaks.
Measurement of the Modal Parameters of a Space Structure in Zero Gravity

An analytic and experimental study of the changes in the modal parameters of space structural test articles from 1 to 0 g is presented. Deployable, erectable, and rotary modules were assembled to form three one- and two-dimensional structures in which variations in bracing wire and rotary joint preload could be introduced. The structures were modeled as if hanging from a suspension system in 1 g, and unconstrained, as if free floating in 0 g. The analysis is compared with ground experimental measurements made on a spring/wire suspension system with a nominal plunge frequency of 1 Hz and with measurements made on the Shuttle middeck. The degree of change in linear modal parameters, as well as the change in nonlinear nature of the response, is examined. Trends in modal parameters are presented as a function of force amplitude, joint preload, and ambient gravity level.
The sensitivity of acousto-optic sensing measurements to absorption changes in superficial and deep layers

Near infrared spectroscopy is a widely adopted optical sensing technique to measure tissue oxygenation non-invasively in human tissues such as the brain and muscle. However, in many situations, the region of interest is beneath a superficial layer, e.g., muscle overlaid by a superficial layer of skin and fat, which can affect the accuracy of the optical measurement. By applying focused ultrasound in the region of interest, acousto-optic (AO) sensing techniques can potentially provide a measurement less susceptible to physiological changes in the superficial layer. In this work, a digital correlator based AO system has been used to perform a series of phantom experiments to assess the sensitivities of the AO and optical measurements (both in reflection modes) to absorption changes (μa = 0.0235, 0.05, 0.1, 0.2, and 0.3 cm-1) in three different locations, including one deep location (23 mm away from the surface) and two superficial locations (8 mm away from the surface). Our results show that the AO measurements have a higher sensitivity factor to the absorption change in the deeper location (177 % cm) than the optical measurements (16 % cm). For the two more superficial locations, the AO measurements have lower sensitivity factors (-5 % cm and 56 % cm) than the optical measurements (194 % cm and 101 % cm). This study has shown the potential of the AO technique for physiological monitoring, which requires a technique to be sensitive to oxygenation changes in the deeper layer while minimizing any contamination from the superficial layer.
Regolith Layer Thickness Mapping of the Moon by Radar and Optical Data

Abstract Mapping of regolith layer thickness for the lunar nearside is carried out with Arecibo radar data at 70 cm wavelength (T. W. Thompson 1987, Earth Moon Planets37, 59–70) and distributions of iron and titanium content derived from Earth-based optical data (Yu. Shkuratov et al. 1999, Icarus137, 222–234). For the mapping a new simple model of radio wave multiple scattering in the regolith layer was used. A comparison of this map with independent estimates of regolith layer thickness for landing sites and other areas of the lunar surface showed a good correlation. It was found that regional variations of thickness are almost the same for maria and highlands, though the average thicknesses are different (5 and 12 m, respectively). A relatively thin regolith layer (4 m) covers a portion of Mare Serenitatis, Mare Tranquillitatis, and Mare Humorum, while the thickest regolith layer occurs in Mare Nectaris (9 m). A thin regolith layer is a characteristic of the cryptomare Schiller-Schickard. Very small regolith thickness corresponds to the crater floors. In this case, the model cannot yield reliable estimates of thickness; it predicts only a characteristic distance between rock inclusions buried in regolith. A thick highland regolith occurs at the southeast portion of the lunar disk and the highland to the north of Mare Imbrium and Sinus Iridium. For the lunar nearside, the regolith thickness generally correlates with the surface age: the greater the age, the thicker the regolith. The results are consistent with a higher rate of regolith growth for times earlier than 3.5 byr ago, when meteorite flux was much higher.
Consistency and efficiency of regression coefficient estimates in location-scale models

SUMMARY The effect on estimation of regression coefficients in linear location-scale models is investigated when the error distribution is misspecified. It is shown that the maximum likelihood estimator under the incorrect model is still consistent. Its asymptotic efficiency relative to that of the maximum likelihood estimator based on the correct model is obtained and the estimation of asymptotic variances for the regression coefficient estimators is addressed.
Differentiation of the Cholesky Algorithm

Abstract One way to estimate variance components is by restricted maximum likelihood. The log-likelihood function is fully defined by the Cholesky factor of a matrix that is usually large and sparse. In this article forward and backward differentiation methods are developed for calculating the first and second derivatives of the Cholesky factor and its functions. These differentiation methods are general and can be applied to either a full or a sparse matrix. Moreover, these methods can be used to calculate the derivatives that are needed for restricted maximum likelihood, resulting in substantial savings in computation.
Multilevel zero-inflated negative binomial regression modeling for over-dispersed count data with extra zeros

Count data with excess zeros often occurs in areas such as public health, epidemiology, psychology, sociology, engineering, and agriculture. Zero-inflated Poisson (ZIP) regression and zero-inflated negative binomial (ZINB) regression are useful for modeling such data, but because of hierarchical study design or the data collection procedure, zero-inflation and correlation may occur simultaneously. To overcome these challenges ZIP or ZINB may still be used. In this paper, multilevel ZINB regression is used to overcome these problems. The method of parameter estimation is an expectation-maximization algorithm in conjunction with the penalized likelihood and restricted maximum likelihood estimates for variance components. Alternative modeling strategies, namely the ZIP distribution are also considered. An application of the proposed model is shown on decayed, missing, and filled teeth of children aged 12 years old.
Comparison of photospheric current helicity and subsurface kinetic helicity

We make a comparison between photospheric current helicity and subsurface kinetic helicity in solar active regions. Four parameters are employed: average value of vertical component of current helicity density 〈Bz· (∇×B)z〉 (〈Hc〉), average force-free field factor and mean subsurface kinetic helicity 〈v· (∇×v)/|v|2〉 (αv), which is denoted as two different parameters, 〈αv1〉 and 〈αv2〉, according to different depths beneath the solar surface. A total of 38 active regions are investigated. The results show that the signs of 〈Hc〉 and αave have a typical hemispheric distribution feature. In contrast, the sign of 〈αv1〉 presents the opposite feature to the above two parameters. For 〈αv2〉, there is no obvious preponderance of the sign in each hemisphere as with the other three parameters. Although there is an opposite hemispheric preponderance between the signs of current helicity and that of kinetic helicity at 0–3 Mm beneath the solar surface, the uncertain correlations between 〈Hc〉 and 〈αv1〉, αave and 〈αv1〉, 〈Hc〉 and 〈αv2〉, and αave and 〈αv2〉 (the correlation coefficients are −0.095, 0.118, −0.102 and −0.179, respectively) do not support that the photospheric current helicity has a cause and effect relation with the kinetic helicity at 0–12 Mm beneath the solar surface.
Effects of thermal annealing on noise property and temperature coefficient of resistance of single-walled carbon nanotube films

The effect of thermal annealing on the electrical transport properties of purified and COOH-functionalized single-walled carbon nanotube (SWCNT) films has been investigated and the correlation between the noise property and temperature coefficient of resistance (TCR) has been derived. Thermal annealing has been found highly efficient to improve both noise and TCR properties of the SWCNT films, which is important to applications of SWCNT bolometers. While the improvement may be attributed mainly to the enhanced intertube coupling in the purified SWCNT films, a combined change in both intratube and intertube charge transport is responsible in the case of COOH-functionalized SWCNT films.
Nonlinear harmonic oscillators

The existence is noted of assemblies of an arbitrary number of complex oscillators, or equivalently, of an arbitrary even number of real oscillators, characterized by Newtonian equations of motion ('acceleration equal force') with one-body velocity-dependent linear forces and many-body velocity-independent cubic forces, all the nonsingular solutions of which are isochronous (completely periodic with the same period). As for the singular solutions, as usual they emerge, in the context of the initial-value problem, from a closed domain in phase space having lower dimensionality.
The Jordan decomposition of vector-valued measures

This paper gives criteria for a vector-valued Jordan decomposition theorem to hold. In particular, suppose L is an order complete vector lattice and 6 is a Boolean algebra. Then an additive set function ,u: 6 -* L can be expressed as the difference of two positive additive measures if and only if ,u(d) is order bounded. A sufficient condition for a countably additive set function with values in c0(F), for any set F, to be decomposed into difference of countably additive set functions is given; namely, the domain being the power set of some set. We are concerned here with vector-valued additive set functions defined on some sort of Boolean algebra with vector-values in a (generally order complete) vector lattice. The purpose of this note is to expose conditions that insure such measures can be written as a difference of positive measures, i.e., conditions for a vector-valued Jordan decomposition theorem to hold. For this reason, a measure that can be expressed as the difference of two positive additive measures will be called "decomposable". The decomposability of vector measures per se was first studied by C. E. Rickart in a 1943 Duke Mathematical Journal article where he established a Lebesgue decomposition theorem for the class of "strongly bounded" additive measures. This result was later re-established (although it was not realized at the time) by J. J. Uhl, Jr. [10] who also presented a Yosida-Hewitt decomposition theorem for "strongly bounded" measures. In [3], Diestel and Faires exhibited several decomposition theorems of the Jordan type, however, they did not give necessary and sufficient conditions for the decomposability of a vector measure. Our first result supplies these conditions, although, as is indicated, only one part of the proof is new. So, let E be a Boolean algebra, S. the vector lattice of simple functions over E endowed with the uniform norm, and L a vector lattice. If tt: C -> L is an additive set function, then the operator T : S, -> L associated with yt is defined by n n T(, aic) = ai fL(ai) Received by the editors January 24, 1975 and, in revised form, February 12, 1976. AMS (MOS) subject classifications (1970). Primary 46G10; Secondary 28A25. Copyright 6) 1977, American Mathematical Society
On the accuracy of the Eddington approximation for radiative transfer in the microwave frequencies

Radiative transfer calculations in the presence of clouds and precipitation simplify as the wavelengths of the radiation approach the Rayleigh scattering regime. In particular, the transfer of microwave radiation is often simpler than the equivalent calculations at shorter wavelengths because the order of quadrature and moments of the phase function needed for the treatment of scattering decrease as the wavelength increases. The purpose of this paper is to examine how well an Eddington approximation can reproduce brightness temperatures obtained from a more complete, N-stream discrete ordinate solution in the microwave regime. Radiation propagating through a plane parallel medium will be considered in this discussion. Although model discrepancies are complicated functions of the cloud constituents, the differences between an eight-stream discrete ordinate solution and an analytical Eddington solution were generally small, ranging from 0 to 6°K when only one uniform layer of hydrometeors was considered. When realistic, multilayered cloud hydrometeor profiles were used, the differences between these two models never exceeded 3°K over the entire range of microwave frequencies considered (6.6–183 GHz). The models agreed to within 0.2°K in the absence of scattering constituents.